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Design and Analysis of a Micro Solar Electric Vehicle
for Application in Pakistan
By
©Ali Husnain
MUN ID: 202095985
A thesis submitted to the School of Graduate Studies in partial fulfillment of the
requirements for the degree of
Master of Engineering
Faculty of Engineering and Applied Sciences
Memorial University of Newfoundland
July 2022
St. John’s Newfoundland and Labrador Canada
ii
Abstract
Global transport sector is the third largest contributor of greenhouse gas emissions.
Governments around the world as well other global stakeholders realize the intensity
of the situation and are transitioning towards zero or low-emissions transportation
modes in order to reduce greenhouse gas emissions and stop climate change. While
the global electric vehicle (EV) adoption is on rise, developing countries like Pakistan
have been facing many obstacles in the face of EV adoption such as shortfall of
electricity, high EV prices, low average income and absence of commercial and
residential charging infrastructure. This thesis proposes a design of a micro solar
electric vehicle, which would address the existing challenges and provide an
economical yet feasible solution. The design and system sizing of the micro solar EV
was done in HOMER Pro. Based on the techno-economic feasibility analysis
completed in HOMER, a dynamic model of the micro solar EV was created in
Simulink. This comprehensive model includes PV generation, maximum power point
tracking, battery charging and discharging, DC-motor operation and speed control of
the electric vehicle, while taking into consideration environmental factors like
irradiance and temperature. Moreover, a detailed ready to build, instrumentation and
control design of the car was developed in Tinkercad. The Tinkercad model was
divided into two parts with the first part covering the control and monitoring circuit
for the vehicle, and the second part covering the auxiliary circuit for the vehicle.
Lastly, conclusions are provided based on the research conducted in each section of
this thesis, and areas for future research have been identified.
iii
Acknowledgement
I would like to thank my supervisor, Dr. Tariq Iqbal, for bringing the weight of his
considerable experience and knowledge to this research. His high standards have
made me better at what I do.
To The School of Graduate Studies (SGS) and Faculty of Engineering and Applied
Science, Memorial University of Newfoundland, thank you for the opportunity to
prove to myself that I am, in fact, worthy of this degree.
To my parents, siblings, and friends that became family, thank you for all the
encouragement and support during the past two years.
iv
Table of Contents
Abstract ..................................................................................................................... ii
Acknowledgement .................................................................................................... iii
Table of Contents ..................................................................................................... iv
List of Figures ........................................................................................................... 1
List of Tables............................................................................................................. 4
List of Abbreviations ................................................................................................. 5
CHAPTER 1: INTRODUCTION & LITERATURE REVIEW .................................. 6
1.1. Introduction .................................................................................................... 6
1.1.1. Electric Vehicle Adoption around the World ............................................ 6
1.1.2. EV Deployment Scenario in Pakistan ....................................................... 8
1.2. Literature Review ........................................................................................... 9
1.2.1. History of Solar Cars.............................................................................. 10
1.2.2. Solar Races ............................................................................................ 11
1.2.3. Commercial Solar Cars .......................................................................... 12
1.2.4. Design of Small Solar Cars .................................................................... 13
1.2.5. Solar-Powered Rickshaw ....................................................................... 15
1.3. Motivation .................................................................................................... 16
1.4. Research Scope ............................................................................................. 19
1.5. Thesis Structure ............................................................................................ 20
v
References ............................................................................................................... 22
CHAPTER 2: SYSTEM DESIGN AND PV SIZING OF A MICRO SOLAR
ELECTRIC VEHICLE FOR PAKISTAN ................................................................ 25
Abstract ................................................................................................................... 26
Keywords ................................................................................................................ 26
2.1. Introduction .................................................................................................. 27
2.1.1. EV Deployment Scenario in Pakistan ..................................................... 27
2.2. Site Selection ................................................................................................ 28
2.2.1. Solar Radiation at the Chosen Location .................................................. 29
2.3. System Sizing ............................................................................................... 30
2.3.1. Choice of a System Sizing Tool ............................................................. 30
2.3.2. Major Components of the System .......................................................... 30
2.3.2.1. Load .................................................................................................... 31
2.3.2.2. Renewable Energy Source: Solar Panels .............................................. 33
2.3.2.3. Battery Storage .................................................................................... 34
2.4. System Design .............................................................................................. 35
2.4.1. Simulation Results ................................................................................. 36
2.5. Conclusion .................................................................................................... 41
References ............................................................................................................... 42
CHAPTER 3: DYNAMIC MODELING OF A MICRO SOLAR ELECTRIC
VEHCLE USING SIMULINK ................................................................................ 43
Abstract ................................................................................................................... 44
vi
Keywords ................................................................................................................ 44
3.1. Introduction .................................................................................................. 45
3.2. Literature Review ......................................................................................... 45
3.3. Design of a Micro Solar EV .......................................................................... 47
3.4. Dynamic Modeling of a Micro Solar EV ....................................................... 49
3.4.1. PV Array ............................................................................................... 50
3.4.2. Maximum Power Point Tracking (MPPT) Controller ............................. 52
3.4.3. DC-DC Converter .................................................................................. 55
3.4.4. Li-Ion Battery ........................................................................................ 57
3.4.5. AC-DC Charger ..................................................................................... 58
3.4.6. DC Machine........................................................................................... 59
3.4.7. Speed Controller .................................................................................... 60
3.5. Simulation Results and Discussion ................................................................ 61
3.5.1. PV Operation ......................................................................................... 61
3.5.2. Battery Operation ................................................................................... 62
3.5.3. DC-Machine Operation .......................................................................... 62
3.5.4. DC-Machine Operation Under Variable Load ........................................ 63
3.5.5. Speed Control ........................................................................................ 63
3.6. Conclusion .................................................................................................... 69
References ............................................................................................................... 71
CHAPTER 4: INSTRUMENTATION AND CONTROL DESIGN FOR A
MICRO SOLAR ELECTRIC VEHICLE ............................................................ 74
vii
4.1. Introduction .................................................................................................. 74
4.2. Choice of Design Tool .................................................................................. 74
4.3. Design Principle............................................................................................ 75
4.4. Major Components........................................................................................ 77
4.4.1. DC-DC Converter .................................................................................. 77
4.4.2. LCD Display .......................................................................................... 78
4.4.3. Forward/Reverse Control ....................................................................... 79
4.4.4. Speed Control ........................................................................................ 79
4.4.5. RPM Meter ............................................................................................ 80
4.4.6. Speedometer .......................................................................................... 80
4.4.7. Odometer ............................................................................................... 80
4.4.8. Battery Voltage & SOC ......................................................................... 81
4.4.9. PV Voltage & Output Power .................................................................. 81
4.4.10. Headlights .......................................................................................... 82
4.4.11. Turn Signals ....................................................................................... 82
4.4.12. Hazard Lights ..................................................................................... 82
4.4.13. Taillights ............................................................................................ 82
4.4.14. Horn ................................................................................................... 83
4.4.15. Windshield Wipers ............................................................................. 83
4.4.16. User Interface ..................................................................................... 83
4.5. Tinkercad Model ........................................................................................... 84
viii
4.6. Conclusion .................................................................................................... 86
CHAPTER 5: CONCLUSION AND FUTURE WORK ........................................... 87
5.1. Conclusion .................................................................................................... 87
5.2. Future Work.................................................................................................. 91
Appendix A ............................................................................................................. 93
Wiring Schematics ............................................................................................... 93
Appendix B ............................................................................................................. 96
Arduino Code for Control Circuit ........................................................................ 96
Arduino Code for Auxiliary Circuit ..................................................................... 99
List of Publications ................................................................................................ 105
1
List of Figures
Figure 1: Electric vehicle deployment around the globe, 2010-2020[1] ...................... 7
Figure 2: University of Michigan and University of Minnesota solar cars compete in
the American Solar Challenge[11] ........................................................................... 11
Figure 3: Map of Bahawalpur, Pakistan ................................................................... 29
Figure 4: Solar radiation data for Bahawalpur, Pakistan. (Source: NREL) ................ 29
Figure 5: Monthly average temperature data for Bahawalpur, Pakistan (Source:
NASA POWER) ...................................................................................................... 30
Figure 6: Choice of vehicle for solar system design [4] ............................................ 31
Figure 7: Daily load profile ...................................................................................... 33
Figure 8: Kyocera KD 145 SX-UFU module [5] ...................................................... 33
Figure 9: Discover AES 1.0 kWh 24 V DC battery [6] ............................................. 34
Figure 10: System modelled in HOMER pro............................................................ 35
Figure 11: Cost summary of the system ................................................................... 36
Figure 12: Monthly electric production by solar panels ............................................ 37
Figure 13: Daily solar output by the solar panels ...................................................... 37
Figure 14: Electrical load served by solar panels throughout the day ........................ 38
Figure 15: Battery input power ................................................................................ 39
Figure 16: Power sources comparison ...................................................................... 40
Figure 17: System design of micro-solar electric vehicle in HOMER pro [6] ........... 48
Figure 18: Block diagram of the dynamic model ...................................................... 50
Figure 19: Equivalent circuit of a PV module [34] ................................................... 51
Figure 20: PV curve of our chosen PV module ........................................................ 52
Figure 21: P&O algorithm working principle [34] ................................................... 53
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Figure 22: P&O algorithm flowchart........................................................................ 54
Figure 23: DC-DC converter (buck converter) [36] .................................................. 55
Figure 24: Buck converter operation (switch ON) [36] ............................................ 56
Figure 25: Buck converter operation (switch OFF)[36] ............................................ 56
Figure 26: Equivalent circuit of a rechargeable battery model .................................. 58
Figure 27: AC-DC charging block ........................................................................... 59
Figure 28: voltage to PWM signal converter block .................................................. 60
Figure 29: Simulink model of the proposed micro solar electric vehicle ................... 61
Figure 30: Variable irradiance values to measure PV response ................................. 64
Figure 31: PV voltage and current variance as per changing irradiance .................... 64
Figure 32: Battery charging mode (from PV modules) ............................................. 65
Figure 33: Battery discharging mode (during motor operation) ................................ 65
Figure 34: battery charging mode (from AC source) ................................................ 66
Figure 35: DC machine normal operation ................................................................ 66
Figure 36: DC machine forward and reverse operation............................................. 67
Figure 37: Variable load profile for DC machine ..................................................... 67
Figure 38: DC machine dynamics under variable load ............................................. 68
Figure 39: Variable speed reference for DC machine ............................................... 68
Figure 40: DC machine dynamics under variable speed reference ............................ 69
Figure 41: Block diagram for control and monitoring circuit for micro solar electric
vehicle ..................................................................................................................... 76
Figure 42: Block diagram for auxiliary circuitry for a micro-solar electric vehicle ... 76
Figure 43: Block diagram for main power stage of the vehicle ................................. 78
Figure 44: LCD used to display real-time data ......................................................... 79
Figure 45: UI for micro solar electric vehicle ........................................................... 84
3
Figure 46: Tinkercad model of control and monitoring unit ..................................... 84
Figure 47: Tinkercad model of the auxiliary circuit .................................................. 85
Figure 48: Wiring schematics for control and monitoring circuit .............................. 93
Figure 49: Wiring schematic for auxiliary circuitry Part 1 ........................................ 94
Figure 50: Wiring schematic for auxiliary circuitry Part 2 ........................................ 94
Figure 51: Wiring schematic for auxiliary circuit Part 3 ........................................... 95
4
List of Tables
Table 1: Vehicle specifications ................................................................................ 32
Table 2: Simulation results of HOMER pro ............................................................. 35
Table 3: Emissions by the designed system .............................................................. 40
Table 4: Vehicle Specifications used for the design [6] ............................................ 47
Table 5: System sizing carried out in HOMER pro [33] ........................................... 48
5
List of Abbreviations
EV Electric Vehicle
GHG Greenhouse Gas Emissions
PV Photovoltaic
DC Direct Current
AC Alternating Current
O&M Operations and Maintenance
NPC Net Present Cost
HOMER Hybrid Optimization of Multiple Energy Resources
SOC State Of Charge
MPPT Maximum Power Point Tracking
PWM Pulse Width Modulation
COE Cost Of Energy
HOMER Hybrid Optimization of Multiple Energy Resources
P&O Perturb and Observe
SEPIC Single-ended Primary Inductor Converter
CEMF Counter-Electromotive Force
CCCV Constant Current Constant Voltage
LCD Liquid Crystal Display
RPM Rotations per Minute
PROM Programmable Read Only Memory
6
CHAPTER 1: INTRODUCTION & LITERATURE
REVIEW
1.1. Introduction
For most of our history, human beings have always relied on some form of energy.
These forms of energy used to be very basic in the beginning such as burning biomass
or animal muscle. The energy dynamic of the world changed with the advent of
industrial revolution, which unlocked a new source of energy, i.e., fossil fuels.
Even today, a few centuries later, our world is still heavily reliant on the consumption
of fossil fuels (coal, oil, gas) in order to meet the needs of the modern society.
However necessary these fossil fuels might be, their consumption comes at the price
of the environment. When burned, fossil fuels produce carbon dioxide and a variety
of other greenhouse gases, which are largest contributor to global climate change and
air pollution across the globe.
Global transport sector is one of the biggest consumer of fossil fuels. However, the
advent of electric vehicles (EVs) marks a new era in the history of transport by
providing a cleaner alternative to hydrocarbon-powered transportation.
1.1.1. Electric Vehicle Adoption around the World
Governments around the world as well other global stakeholders have realized the
intensity of situation and are taking steps to counter the global climate change by
reducing the emissions of greenhouse gases. Transport sector being the third largest
contributor to GHG emissions [1] automatically becomes a priority. The steps taken
7
to reverse the global warming effect and stop climate change include but are not
limited to;
transition towards zero or low-emissions transportation modes,
increase public transit ridership,
increase the use of cleaner fuels, and
encourage denser communities.
The transition from internal combustion powered cars to electric vehicles falls under
the first category, i.e., zero or low-emissions transportation modes and has been the
number one driver towards a cleaner future. For the past ten years, electric vehicle
deployment has been growing rapidly. According to the Global EV Outlook 2019,
published by International Energy Agency, the global stock of passenger EVs passed
5 million in 2018, which is a 63% increase as compared to the year before. Figure
below shows the growth in EV deployment around the globe for years 2010-2020 [1].
Figure 1: Electric vehicle deployment around the globe, 2010-2020[1]
8
1.1.2. EV Deployment Scenario in Pakistan
While the global EV deployment is growing at a rapid rate, the same cannot be said
about Pakistan and a number of reasons are to be blamed for this stagnancy in EV
deployment across Pakistan.
Firstly, the energy scenario in Pakistan is not ideal to support the EV infrastructure at
a large scale. In the past decade, Pakistan has suffered from one of the worst energy
crisis when the country faced a persistent gap between the demand and available
system generating capacity. The power shortages as a result of this energy crisis
impacted the country’s annual output, employment and exports.
In the recent years, Pakistan has focused a lot on developing large-scale power
generation projects in order to meet the growing electricity demand, and to some
extent, they have succeeded. According to the Pakistan Economic Survey 2019-20,
the country’s installed generation capacity reached 37,402 MW in 2020 [2], whereas
the maximum total demand from both industrial and residential estates was never
above 25,000 MW. However, the distribution and transmission capacity is stalled at
approximately 22,000 MW, meaning at peak demand times Pakistan was suffering
with a shortfall of electricity by about 3000 MW [3].
Apart from the electricity shortfall, there are a number of other reasons why Pakistan
is lagging behind in EV adoption including but not limited to, high prices of electric
vehicles, low average income, absence of commercial charging infrastructure, and last
but not least the inability of residential electrical infrastructure to charge an electric
vehicle.
Talking about the prices of the cars, an average electric car costs anywhere between
$30,000 to $40,000 and while no additional taxes or import duties are imposed by the
9
Pakistani government on the import or development of EVs in the country, the price is
still higher than most cars sold in Pakistan. The average income of a Pakistani
household is 81,800 PKR (Pakistani Rupee) per month [4], which translates to
$485.46 as per the September 2021 conversion rates. This number is significantly
lower than the US average of $7900 per month. Similarly, if we look at the price of
cars in Pakistan, Suzuki’s 660cc Alto was the best-selling car for the year 2020 [5].
This car retails for 1,113,000 PKR (Pakistani Ruppee) which translates to $6,605 as
per the September 2021 conversion rates. Therefore, the price difference between an
average EV and the cars in Pakistan is just too exorbitant to ignore.
Since there are not many EVs being offered by automobile manufacturers in Pakistan,
there is a complete lack of commercial charging infrastructure in the country. As
compared to US, which has nearly 43,000 public EV charging stations and the leader
in EV adoption Norway, which has nearly 16,000 public EV charging stations,
Pakistan only has less than half a dozen public EV charging stations. Although plans
are underway to develop more charging stations, these projects would only be making
an addition of 24 new public EV charging stations [6].
Lastly, the idea of charging an EV at a residential charging port also seems far fetched
as the average amount of current needed by an EV to charge at a reasonable speed of
25 miles per hour is about 32 A. This amount of current is simply not available for a
single -phase residential meter in Pakistan, which are rated at about 10 A at most.
1.2. Literature Review
A solar powered electric vehicle or as it is commonly referred to, ‘solar car’ is a
vehicle used for land transport and runs either entirely or partially on power from the
10
sun in the form of solar energy. Most solar powered EVs utilize a photovoltaic array
consisting of PV cells in order to convert the solar energy shinning on to the
photovoltaic array, which converts it into a usable form of energy, i.e., electricity.
This electricity is used to drive the electric motors, which carry out the propulsion of
the vehicle [7].
Most solar cars make the use of batteries as a form of energy storage devices in order
to save the electricity being produced by the photovoltaic array mounted on the body
of the vehicle. These batteries not only help ensure a constant supply of electricity but
also serve as a power bank for when there is no sunlight and the photovoltaic array
mounted on the car is not producing any electricity. In solar powered EVs, which only
take a part of their energy from the sun, the same batteries act as a secondary source
of energy and can be charged by a utility EV charger connected to the grid [8].
1.2.1. History of Solar Cars
The world’s first solar powered vehicle was presented at the General Motors
Powerama auto show held in Chicago, Illinois, by William G. Cobb, a General
Motors Corp. executive, in 1955 [9]. The showcased vehicle was a miniature 15-inch
long vehicle, called ‘Sunmobile’, which made use of 12 photoelectric cells made of
selenium (a non-metal substance, which also possesses conducting properties). The
cells were built into the car and when sunlight shined on them, they produced enough
energy to turn a tiny motor connected to the drive shaft of the sunmobile [9]. More
than 65 years later, we are yet to see a mass-produced solar car to hit the consumer
market.
11
1.2.2. Solar Races
When it comes to the development of a road worthy solar powered electric vehicle,
solar car races have contributed a lot. There is a large number of racing events being
held globally for the past decade or so, in which innovative designs of solar powered
cars from around the world come together to compete over distances of up to a few
thousand kilometers. These solar car races have pushed solar design teams across the
world to achieve high efficiencies, aerodynamics and low energy consumption when
working on the design of these solar cars.
The solar races being held around the world have a wide variety of cars competing in
them from racing cars to small sized solar powered EV and a cruiser that comfortably
fits a family of five. Two of the most popular solar challenges are the World Solar
Challenge held in the Australian continent, over a distance of 3000 kilometers [10],
and the American Solar Challenge which stretches all the way from Omaha, Nebraska
to Bend, Oregon [11].
Figure 2: University of Michigan and University of Minnesota solar cars compete in
the American Solar Challenge[11]
12
1.2.3. Commercial Solar Cars
In the past decade, multiple automobile manufacturers and electric vehicle technology
startups have come forward with their own version of solar powered electric vehicles.
While none of these vehicles have made it to the consumer, they all represent a big
step towards the realization of a dream, that a solar powered electric vehicle will one
day be the most common mode of transport.
The first one to come out with a solar powered electric vehicle was a US based startup
called Aptera [12]. The company showcased a prototype with exceptional design and
very low drag coefficient of only 0.13. The company also claims that the 3D designed
car can produce up to 700 watts of electricity in good solar conditions, thus providing
a range of up to 40 miles per day [12]. The second solar car to be presented to the
world was by a Netherlands based startup called Lightyear, who recently came out
with their first car Lightyear One [13]. The solar car is a full-sized luxury sedan with
a very aerodynamic design and as per company claims has a range of up to 725
kilometers (solar and battery combined). The company also claims that Lightyear One
can add a range of 7,000 to 20,000 kilometers annually from the sun, if you live in an
area with appropriate amount of sunlight [13].
Similarly, a Swedish startup has come up with a solar powered electric car called
Sion, which is a family sized van, with a range of up to 305 kilometers [14]. The car
has 248 solar cells seamlessly integrated into the body of the car, which according to
the company add up to 112 kilometers of range per week to the car’s battery [14].
Another Swedish startup called Clean Motion, which focuses on providing urban
transport solution through solar-powered electric vehicles [15]. Clean Motion has
recently launched their latest small, modular delivery van, which is powered by the
13
sun. The prototype boasts about 600 watts of solar panels and can supposedly add a
range of 130 kilometers per day on a bright sunny day [15].
Last but not least, one of the most interesting design was put forward by a startup
named Squad Mobility, who recently launched their first solar car named Squad [16].
The Squad is a micro car, which gives a range of about 20 kilometres from solar
energy and as per the average micro car usage in Europe of 12 kilometres, Squad can
be fully sustainable [16].
1.2.4. Design of Small Solar Cars
When talking about the design of small solar cars, there has been plenty of research
done on the topic. In this section, some of the designs that were put forward for small
solar powered electric vehicles will be discussed.
To start, P.O. Babalola and O.E.Atiba from Covenant University did a comprehensive
review of solar powered cars. The review covers everything from the history of solar
cars to how the design and efficiency considerations have changed over the period of
65 years. Some of the principles that need to be kept in mind when designing a small
solar powered electric vehicle include but are not limited to: the design should be less
complex than conventional cars, the number of solar cells that can be integrated on to
the car depend on the size of the car as well as allowable solar cells per Winston rules,
and due to high maximum efficiency of 80-90%, a DC brush permanent magnet motor
should be used as the primary driver [17]. H. Koten et al. in his research on the design
consideration of solar powered cars also discusses some important principles to be
kept in mind when designing a solar car including low drag resistance, being light-
weight, and must have low rolling resistance [18]. In this same study, the authors
14
make the use of solar powered Stirling engine technology instead of a conventional
PV conversion technology [18].
The first car design that is going to be discussed in this paper was made by
Engineering students at University of Kentucky, who designed a solar car for the
North American Solar Car Challenge [19]. The car called Gato del Sol III was
powered by 480 silicon monocrystalline PV cells, integrated making the use of
MPPTs. The car was powered by a 90% efficient brushless DC motor. The car with
its battery back of 5kWh was able to travel over 75 miles, in the absence of sun [19].
In another comprehensive research published in the Journal of Progress in
Photovoltaics, the authors present innovative design solutions for solar powered
electric mobility applications [20]. The paper discusses 11 of the designs that were
developed at University of Twente, which encompass a variety of mobility
applications. The authors discussed four of those conceptual designs as case studies
and discusses the design challenges that needed to be addressed. These challenges
included: limited space available for integrating PV cells, effective visual
communication of concept’s intended function, and technical limitations of some
proposed charging methods [20].
Another important solar powered electric vehicle design is known as the
UltraCommuter designed by researchers at University of Queensland [21]. The paper
showed that the solar array on-board the vehicle provides substantial supplementation
of electricity required for normal driving. By normal driving, the authors mean that
the UltraCommuter can power almost 90% of the journey of an average QLD
passenger vehicle [21].
15
Ashrafee et al. discusses the design and fabrication of a solar powered toy car. The
concept is very much similar to an actual solar powered car, however, given the small
amount of power required to propel the toy car, the design does not translate to a car
to be considered practical [22].
S. Ahmed et al. conducted a research that proposed a design of a prototype solar
powered lightweight vehicle, capable enough to carry two people. The study also
presents an economic analysis of the car, which shows that over a period of 20 years,
the cost of ownership of the solar car is 1/9th the total cost of ownership of a gas
powered car [23].
1.2.5. Solar-Powered Rickshaw
In developing countries, rickshaws are an important mode of public transport. These
vehicles are usually equipped with small motors and are capable of carrying up to 5
people at low cruising speeds. The use of solar-power as the main source of power in
a rickshaw makes a lot of sense as their watt/mile energy consumption is low and only
a few kWh of energy lasts a long way.
N. Saleh et al. proposes the design of solar-powered hybrid rickshaw for commercial
use in Pakistan. The study presents four prototypes of passenger rickshaws and one
prototype for cargo loading type rickshaw. The authors then performed an average
speed analysis test of the rickshaw prototypes and found that the rickshaw could
produce enough power to last for 40 miles per charge [24].
Similarly, researchers from Institute of Information Technology in Bangladesh,
presented the design of a solar powered rickshaw, where they took a traditional
battery operated auto-rickshaw and proposed a microcontroller based design to
convert the rickshaw into a solar powered vehicle. The paper also presents a
16
performance evaluation of the rickshaw, which shows that the life cycle cost (LCC)
analysis is minimum as compared to battery-operated auto-rickshaw [25].
1.3. Motivation
There exists a significant gap in the research being performed on solar powered
electric vehicles and what is needed in the market. A large number of studies and
research projects, which focus on the design of a solar powered car have been
discussed. However, almost all of them, with the exception of few lack one or another
crucial component that is stopping the mass adoption of a solar powered electric
vehicle.
Starting from the solar races, most of the solar cars participating in those competitions
are the epitome of innovation, efficiency and aerodynamics. These cars can produce a
record amount of energy from solar arrays integrated into them, they can achieve high
speeds. However, the number of amenities that these cars come equipped with are
very small to none, making these cars not suitable for commercial use. Also to be kept
in mind is the fact that these cars barely have the space to hold the driver of the car,
let alone a passenger. Most of these cars are also made from fiber, in order to keep
their weight low, which makes them unsuitable to be used on the road.
Talking about the commercial choices available for a solar powered electric vehicle,
most of the options available are only prototypes and while the claims made by their
manufacturers are impressive, they have almost zero proof when it comes to backing
those claims. Most of these cars seem nothing more than a marketing gimmick, as all
of these prototypes have been launched for over 4-5 years now, but the market is yet
to see them on the road. Another important fact to note here is that most of these cars
17
come with an enormous price tag of more than $100,000 USD, which is even more
expensive than a traditional electric vehicle.
Finally, there are design propositions for small solar car designs. While there are
some reasonable designs and prototypes showcased by those studies, almost all of
them fail to provide a comprehensive design for a solar powered electric vehicle.
Some of the studies focus on the sizing part of the electric vehicle, others study it
from an economical point of view and last but not least, most studies focus on the
performance evaluation of the car. A study that provides a one-window solution to the
design of a solar powered car i.e. cover everything from the design, sizing, economic
analysis, dynamic modelling, and controller design of the solar powered car is yet to
be found.
When talking about the studies found on solar-powered rickshaw, they present very
reasonable designs; however, they can only be used as a commercial mode of
transport and are not suitable for everyday personal use.
The gaps in the existing literature present a great opportunity to work on the design
and modelling of a small solar powered car, especially for application in Pakistan, as
the dynamics there are different from the ones discussed in the studies mentioned
above.
In addition to the literature gap, there are a few other reasons why this topic is an ideal
choice for the thesis project. Technologists and scientists believe that electric vehicles
are the future of transportation. However, given the lack of electricity abundance
throughout the world, and the high prices of EV technology due to it being in its
initial phases, it is difficult if not impossible for the developing countries to compete
with the developed countries. This motivated me to work on the design of a micro
18
solar EV, which is not only cheaper to develop but also utilizes solar energy as its
primary source, thus overcoming the electricity shortfall problem.
In addition, solar powered electric vehicles provide a number of benefits over their
internal combustion engine counterparts. These benefits include but are not limited to
less maintenance, lower running cost, lower registration costs, better for the
environment, better for the network and for our energy security.
The reason why a solar powered electric vehicle requires less maintenance is that it
has a lot less parts than an internal combustion car. According to a report done by
Forbes, an electric vehicle on average consists of about 20 moving parts, which make
up its drivetrain in comparison to an internal combustion engine vehicle, which has
over 2000+ moving parts [26].
Secondly, the average price of running an electric vehicle is significantly lower than
that of running a gas-powered vehicle. A case study done by Idaho National
Laboratory found out that if the average price of electricity and fuel in US were
assumed, an electric vehicle with energy efficiency of 3 miles per kWh costs about
3.3 cents per mile. Similarly, a gas-powered vehicle with an energy efficiency of 22
miles per gallon costs about 15.9 cents per mile [27]. This number becomes even
lower when we rule out the cost used to charge the electric vehicle, as in our case the
vehicle is being charged directly from solar energy.
Solar electric vehicles, alongside electric vehicles qualify for tax exemptions as well
as relief from custom duties from the governments around the world. Even in
Pakistan, where most vehicles are subjected to a custom duty of as much as half of
their price, EVs are exempt from any kind of tax and customs duty.
19
Talking about the betterment of environment, there is an ongoing argument about how
EVs may not be as clean as they claim to be. However, a solar powered EV has some
of the key differences when it comes to its carbon footprint. Firstly, a solar powered
EV is charged directly from solar energy and thus does not utilize electricity from the
grid, which is often produced using fossil fuels. Secondly, it is true that the production
of an EV and solar panels itself is a carbon positive activity, it is nowhere even close
to the carbon footprint of an ICE car. The carbon footprint of a solar powered EV is
also significantly less than a traditional EV.
1.4. Research Scope
In this thesis, a comprehensive design and modelling of a micro solar electric vehicle
for application in Pakistan will be carried out. The research will be divided in three
portions starting from the sizing of the electric vehicle and choosing all the suitable
components that go on it, in order to make a fully functional micro solar charged
electric vehicle. After this, the detailed modelling of the system in Simulink in order
to analyze how all the parts would come together to form our micro EV, will be
carried. Lastly, an instrumentation and control system for a micro solar electric
vehicle will be designed.
Since the EV being designed is for application in Pakistan, the solar irradiation data
from Punjab, Pakistan will be used.
The research spanned over a period of one year starting from September, 2021 to
August 2022. Each part of the research spanned over a period of 2.5 months.
20
1.5. Thesis Structure
This thesis is divided into five chapters in total. The details of what each chapter
would cover are given below;
Chapter 1 starts with an introduction of the global energy scenario, and how the
current transport sector happens to be the third largest contributor to greenhouse gas
emissions. The global EV adoption, as well as the Pakistani context, when it comes to
the deployment of electric vehicles is discussed. The chapter also includes a detailed
literature review or all the research and development that has been done in this field
from the inception of solar cars, to solar races, commercial solar cars, small solar
powered cars, and solar powered rickshaws. Further, the chapter identifies the gap in
the literature and talks about our motivation to pursue this research.
Chapter 2 of the thesis focuses on the sizing of the system. This chapter includes
everything from the choice of location, choice of vehicle, collection of solar
irradiance data, sizing of the system, selection of the components to be used,
feasibility study and finally an economic analysis of the system.
Chapter 3 of the thesis would focus on the dynamic modeling of the system. In this
part, choice of the software, modelling of all individual components of the system,
simulation of the model and lastly, the results of the simulation will be discussed.
Chapter 4 of the thesis will focus on the design of an instrumentation and control
system for the car. This chapter would outline the software to be used, major
components of the instrumentation and control system, and finally the modeling of the
system.
21
Chapter 5 of the thesis would discuss the conclusions drawn from the previous
chapters and will propose future areas of research that can be undertaken as an
extension to this research.
22
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25
CHAPTER 2: SYSTEM DESIGN AND PV SIZING
OF A MICRO SOLAR ELECTRIC VEHICLE FOR
PAKISTAN
Ali Husnain1, M. Tariq Iqbal2
1,2Electrical and Computer Engineering Department, Faculty of Engineering and
Applied Science, Memorial University of Newfoundland, St. John’s, Canada
A version of the manuscript in this chapter has been presented as a conference paper
in the 2022 IEEE Conference on Technologies for Sustainability (SusTech). As the
primary author in this paper, Ali Husnain carried out the research under the
supervision of M. Tariq Iqbal, the co-author. The MEng candidate performed the
literature review and was involved in system selection, designs, calculations,
simulation, and data analysis. Moreover, he prepared the first draft of the paper. The
co-author supervised the research by actualizing the research ideas, reviewing and
correcting the manuscript.
26
Abstract
The transport sector is the third largest contributor of GHG emissions globally. To
counter this, global EV adoption has been increasing at a rapid rate. However,
Pakistan has been left far behind in this race and is very slow to EV adoption, due to a
number of factors including energy shortfall, lack of purchase power and absence of
charging infrastructure to name a few. Therefore, a design for simple yet economical
micro solar electric vehicle has been proposed. This paper covers the sizing and
system design for the solar PV system for a solar electric vehicle on HOMER Pro. It
also gives an economic analysis of all the components involved.
Keywords
solar EV, solar car, electric vehicle, EV design
27
2.1. Introduction
Climate change has been identified as one of the biggest problems of the modern
world. However, we as human beings, continue to rely heavily on the consumption of
fossil fuels (coal, oil, gas) to meet our daily needs. No matter how necessary it is, the
consumption of fossil fuels comes at the price of environment. When burned, fossil
fuels produce carbon dioxide and a variety of other greenhouse gases, which are
largest contributor to global climate change and air pollution across the globe.
Global transport sector is one of the biggest consumer of fossil fuels and the third
largest contributor of greenhouse gas (GHG) emissions globally. However, the advent
of electric vehicles marks a new era in the history of transport by providing a cleaner
alternative to gas-powered transportation.
For the past ten years, electric vehicle deployment has been growing rapidly.
According to the Global EV Outlook 2019, published by International Energy
Agency, the global stock of passenger electric vehicles (EVs) passed 5 million in
2018, which is a 63% increase as compared to the year before [1].
2.1.1. EV Deployment Scenario in Pakistan
Firstly, the energy scenario in Pakistan is not ideal to support the electric vehicle (EV)
infrastructure at a large scale. Pakistan has suffered from one of the worst energy crisis
over the past decade, due to a large and persistent gap between the demand and
available system generating capacity. In more recent years, Pakistan has focused a lot
on developing large-scale power generation projects in order to meet the growing
electricity demand, and to some extent, they have succeeded. The current installed
generation capacity stands at 37,402 MW in 2020 [2], whereas the maximum total
demand was never above 25,000 MW. However, the distribution and transmission
28
capacity is stalled at approximately 22,000 MW, meaning at peak demand times
Pakistan was suffering with a shortfall of electricity by about 3000 MW [3].
Apart from the electricity shortfall, there are a number of other reasons why Pakistan is
lagging behind in EV adoption including but not limited to, high prices of electric
vehicles, low average income, absence of commercial charging infrastructure, and last
but not least the inability of residential electrical infrastructure to charge an electric
vehicle. At typical electrical service is 5A or 10A at 220V to supply house load, which
is not enough to charge an EV at home.
In this chapter, a preliminary design of a micro solar electric vehicle is proposed. The
chapter includes the selection of a location, where the solar electric vehicle will be
driven. This is done in order to use the solar insolation data of the chosen location, as
it varies from region to region. The chapter will also discuss the major components
that are going to be used in the design of solar electric vehicle. Finally, a solar
powered system design tool called HOMER Pro will be used to do the sizing of the
solar electric vehicle.
2.2. Site Selection
The major motive behind carrying out this research is to design a small solar electric
vehicle for application in Pakistan. Therefore, the country chosen for the selection of
solar radiation data is Pakistan. However, that does not narrow it down any further, as
Pakistan has a diverse geographical landscape and the amount of sun available
throughout the day, is different across different regions of the country. For this
purpose, the city of Bahawalpur, a region with mixed landscape, which can be used as
a representative of the region of Pakistan was selected.
29
Figure 3: Map of Bahawalpur, Pakistan
2.2.1. Solar Radiation at the Chosen Location
The solar radiation and the clearness index data for the chosen location i.e.
Bahawalpur, Pakistan is retrieved from the National Renewable Energy Laboratory
(NREL) global database. This database is integrated into the system design software,
HOMER Pro that we are utilizing in order to carry out the sizing of the system. The
solar radiation and clearness index of the location can be seen in figure 4.
Figure 4: Solar radiation data for Bahawalpur, Pakistan. (Source: NREL)
Another important dataset that goes into the modelling of how much solar power is
needed for the load; is the temperature data for our chosen location. This data has
30
been retrieved from NASA Prediction of Worldwide Energy Resource (POWER)
database. The monthly average temperature data for Bahawalpur, Pakistan can be
seen in figure 5.
Figure 5: Monthly average temperature data for Bahawalpur, Pakistan (Source:
NASA POWER)
2.3. System Sizing
2.3.1. Choice of a System Sizing Tool
In order to perform the sizing of our small solar electric vehicle, a design tool called
HOMER Pro is chosen. Developed by the National Renewable Energy Laboratory
(NREL) in the United States, HOMER stands for Hybrid Optimization of Multiple
Energy Resources, and is a software application that is used to design and analyze
both the technical and financial aspects of a power system for stand-alone, remote and
distributed generation application. HOMER Pro is simple to use, detailed and takes in
all of the necessary variables when it comes to analyzing a power system.
2.3.2. Major Components of the System
When sizing a system in HOMER Pro, a few key components must be added into the
simulation. The first and most important component of the system is the load, which
in our case is a small solar electric vehicle. Other than that, a renewable energy source
31
needs to be added to the system as well as a battery storage solution. Most systems in
HOMER also require a backup generator, a grid source or a converter. However, in
this case, since we are designing an electric vehicle, we would not have a generator or
a grid source. Moreover, the use of a DC electric motor also eliminates the need for a
converter. So the remaining components that we need to model for our system design
in HOMER Pro are load, renewable energy source, and a battery storage solution.
2.3.2.1. Load
As emphasized earlier in this thesis, a small solar powered electric vehicle is to be
designed. Some of the design requirements that we abide by throughout this research
include that the vehicle should be able to fit at least 3 passengers and drive at average
city driving speeds. Therefore, the vehicle design that we have selected is the one
proposed by a Chinese manufacturer called Chang Li [4]. Chang Li is a small
automobile manufacturer, which specializes in producing small electric vehicles at a
very economical price point. The specific vehicle that is being chosen is the 2021
Chang Li XYZ electric car [4]. The vehicle can be seen in figure 6.
Figure 6: Choice of vehicle for solar system design [4]
32
The specifications of the vehicle are as following:
Table 1: Vehicle specifications
Item Description
Brand Name Chang Li
Max. Range 100 km
Dimensions 2450 mm*1350 mm*1750 mm
Wheelbase 1500 mm
No. of seats 3
Motor Size 1200 W
Total Motor Torque 100 Nm
Max Speed 43 km/hr
Now, in order to build a load profile to be input into HOMER, the amount of power
the vehicle would consume over a set distance needs to be calculated. For this load
consumption, we have assumed that the vehicle would cover a distance of 30 km per
day, which happens to be equal to the average distance covered by a commuter in
Pakistan.
Distance covered: 30 km
Average speed: 30 km/hour
Motor nominal power: 1.2 kW
Energy consumption = Motor power * Time
33
= 1.2 kW * (1 hour) = 1.2 kWh.
Hence, the load profile in HOMER Pro was set accordingly, as shown in figure 7.
Figure 7: Daily load profile
2.3.2.2. Renewable Energy Source: Solar Panels
In order to meet the load demand, a renewable energy source, i.e. solar panels were
added. The solar panel chosen is Kyocera KD 145 SX-UFU [5]. There are multiple
reasons behind the choice of this solar panel, which include easy availability, high
efficiency and a low temperature coefficient. The chosen solar panel module has the
following specifications:
Name: Kyocera KD 145 SX-UFU
Abbreviation: Kyoc145
Panel type: Flat Plate
Rated capacity (kW): 0.145
Temperature coefficient: -0.460
Operating temperature (°C): 45.00
Efficiency (%): 14.4
Figure 8: Kyocera
KD 145
SX-UFU module [5]
34
Capital cost (Rs): 6,960.00
Replacement cost (Rs): 6,960.00
O&M cost (Rs): 0.00
Time (Years): 25.00
When talking about the placement of solar panels on the electric vehicle, they will be
laid flat on the roof the vehicle.
2.3.2.3. Battery Storage
In addition to the solar panels, a battery storage system is needed for the electric
vehicle in order to ensure a continuous supply of electricity, when the sun is not
providing enough solar power. The battery size can also be increased to provide
longer range to the electric vehicle and the battery can also be charged passively by
connecting it to an electrical outlet in the case of bad weather or absence of sun etc.
The battery module chosen is Discover AES 1.0 kWh 24 VDC [6]. It is a LI-Ion LFP
battery and has the following specifications.
Name: Discover AES 1.0kWh 24VDC
Nominal voltage (V): 24
Nominal capacity (kWh): 0.96
Nominal capacity (Ah): 40
Roundtrip efficiency (%): 95
Maximum charge rate (A/Ah): 1
Maximum charge current (A): 40
Maximum discharge current (A): 200
Capital cost (Rs): 54,376.00
Replacement cost (Rs): 54,376.00
Figure 9: Discover AES 1.0 kWh 24 V DC
battery [6]
35
O&M cost (Rs): 0.00
Time (Years): 10
2.4. System Design
After making the choice of all important components, HOMER Pro was used to carry
out a detailed technical and economic analysis of the system and provide a feasible
outcome for the research. The system modeled by HOMER Pro is shown in the figure
10 below:
Figure 10: System modelled in HOMER pro
For this modeled system, HOMER Pro also provided us with the most feasible sizing
of the system as shown in the table below.
Table 2: Simulation results of HOMER pro
Item Quantity
Architecture/Kyoc145 (kW) 0.4375
Architecture/Dis1.0 3
Cost/NPC (Rs) 177013.7
36
Cost/COE (Rs) 54.62492
Cost/Operating cost (Rs/yr) 961.2305
Cost/Initial capital (Rs) 184128
System/Ren Frac (%) 100
System/Total Fuel (L/yr) 0
Kyoc145/Capital Cost (Rs) 21000
Kyoc145/Production (kWh/yr) 766.9749
Dis1.0/Autonomy (hr) 57.6
Dis1.0/Annual Throughput (kWh/yr) 392.1335
Dis1.0/Nominal Capacity (kWh) 2.88
Dis1.0/Usable Nominal Capacity (kWh) 2.88
2.4.1. Simulation Results
The simulation carried out using HOMER Pro gives a few more insights into the
design of the system. This includes financial analysis, monthly energy production,
cash flow, comparison of economics, emissions reports and much more.
The cost summary of the system is as shown in the figure below:
Figure 11: Cost summary of the system
37
Before diving into the detailed results of the system, let us take a look at the monthly
electric production by our designed solar system.
Figure 12: Monthly electric production by solar panels
Since, we have seen how the electric production by the solar panels would vary over
different months throughout the year; let us dive into the detail of our monthly
production, battery operation and load fulfillment.
Figure 13: Daily solar output by the solar panels
As shown in the figure 13, the daily solar output by the solar panels varies throughout
the day, where it starts from almost zero and goes all the way up to 0.28 kW. The
38
chosen location Bahawalpur is located in the south region of Pakistan, which means it
gets plenty of sun, especially during the summer months. This explains the extended
solar output throughout the day as compared to a city located in the Northern region.
The next figure shows the total electrical load served during a day. As per the load
profile, the amount of time, that the car was utilizing solar power was restricted to a
single hour. While the car can still drive throughout the day, given the battery has
been charged directly via an electrical outlet, the curve in the figure given below
shows the amount of time, when the electrical load is being served by the electricity
generated by solar panels.
Figure 14: Electrical load served by solar panels throughout the day
Moving on, figure 15 shows the input power that is going into the battery storage
system. The battery shows a negative input power during the time that the electrical
39
load was served and then once the load is served, the input power is in positive, until
the battery is fully charged.
Figure 15: Battery input power
This becomes clearer, when comparing all three of these variables together in a graph
as shown in figure 16. The graph shows that the solar power output is distributed
throughout the day with the exception of early morning and night. Throughout this
time, the solar panels would charge the batteries placed in our system. However, when
the load utilizes the power, it will be done all in an hour; therefore the batteries would
chip in, as indicated by the negative input power in the figure below. This indicates
the flow of power from the batteries to the load. Soon after the load is served, the
batteries will start charging.
40
Figure 16: Power sources comparison
Last but not least, HOMER Pro also provides the emissions report of the power
system simulated. In this case, since the entire system is making the use of 100% solar
power, the emissions drop to almost zero (only considering the emissions during
operation of the vehicle on solar PV, does not include life cycle emissions). The table
below shows the various emissions by our designed system as simulated on HOMER
Pro.
Table 3: Emissions by the designed system
Emission Type Quantity Unit
Carbon Dioxide 0 kg/yr
Carbon Monoxide 0 kg/yr
Unburned Hydrocarbons 0 kg/yr
Particulate Matter 0 kg/yr
41
Sulfur Dioxide 0 kg/yr
Nitrogen Oxides 0 kg/yr
2.5. Conclusion
This paper presents the basic design of a solar EV for Pakistan. HOMER Pro is used
for system sizing. Presented results shows a successful design and sizing of a micro
solar powered electric vehicle. The designed solar PV system is capable of serving the
electrical load i.e. the DC electric motor of the electric vehicle over a set distance of
30 km. Since the power generation by solar panels is distributed over the day, battery
storage is used to store this surplus energy and supply it when the load requires it.
In the future part of this research, we plan on building a dynamic model for this solar
PV charged electric vehicle, which would include major calculations including
passenger load variation, resistance calculations, load profile over steep/uneven roads
and multiple load profiles throughout the day.
42
References
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http://tribune.com.pk/story/1989618/2-installed-power-production-capacity-rises
(accessed Sep. 23, 2021).
[3] M. Rehman, “Pakistan’s electricity generation has increased over time. So why do
we still not have uninterrupted supply?,” DAWN.COM, Sep. 03, 2018.
https://www.dawn.com/news/1430728 (accessed Sep. 23, 2021).
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mini-ev (accessed Jul. 21, 2022).
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panel (accessed Jul. 21, 2022).
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Battery_p_1414.html (accessed Jul. 21, 2022).
43
CHAPTER 3: DYNAMIC MODELING OF A
MICRO SOLAR ELECTRIC VEHCLE USING
SIMULINK
Ali Husnain1, M. Tariq Iqbal2
1,2Electrical and Computer Engineering Department, Faculty of Engineering and
Applied Science, Memorial University of Newfoundland, St. John’s, Canada
A version of the manuscript in this chapter has been presented as a conference paper
in the 2022 IEEE International IOT, Electronics and Mechatronics Conference
(IEMTRONICS). As the primary author in this paper, Ali Husnain carried out the
research under the supervision of M. Tariq Iqbal as the co-author. The MEng
candidate performed the literature review and was involved in system selection,
designs, calculations, simulation, and data analysis. Moreover, he prepared the first
draft of the paper. The co-author supervised the research by actualizing the research
ideas, reviewing and correcting the manuscript.
44
Abstract
While the global electric vehicle (EV) adoption is on rise, developing countries like
Pakistan have been facing many obstacles in the face of EV adoption such as shortfall
of electricity, high EV prices, low average income and absence of commercial and
residential charging infrastructure. In this thesis, we propose a design of a micro solar
electric vehicle, which would help overcome all of these problems and provide an
economical yet feasible solution. The design and system sizing of the micro solar EV
was done in HOMER Pro. A dynamic model of the micro solar EV was created in
MATLAB/Simulink, which implemented PV generation, maximum power point
tracking, battery charging and discharging, DC-motor operation and speed control of
the electric vehicle, while taking into consideration environmental factors like
irradiance and temperature.
Keywords
solar EV, solar car, electric vehicle, EV design, dynamic modeling
45
3.1. Introduction
Climate change is one of the most pressing issues of the modern world and steps are
being taken around the world to help slow down and mitigate climate change. The use
of electric vehicles is one such bold step that helps reduce the GHG emissions of the
global transport sector and slow down the impact of climate change. Global EV
adoption has been growing at a rapid pace, in developed countries. However, the same
cannot be said about developing countries, such as Pakistan.
The EV adoption in Pakistan is facing many obstacles including but not limited to
electricity shortfall, high prices of electric vehicles, low average income, absence of
commercial charging infrastructure and the inability of residential electrical
infrastructure to charge an electric vehicle. At typical electrical service is 5A or 10A
at 220V to supply house load, which is not enough to charge an EV at home.
Therefore, in this paper, we propose the design of a micro solar electric vehicle,
which holds against all the above-mentioned challenges. This solar EV would have
the ability to take power from the sun in the form of solar energy, throughout the
daytime. It would also be very economical in price and would easily be charged from
the existing residential electrical infrastructure.
3.2. Literature Review
While it has roughly been less than a decade since EV commercialization has become
mainstream and automakers are selling fully functional EVs to consumers. There has
been plenty of research on EVs before that as well. During the literature review part
of this research we came across multiple designs and dynamic models of all types of
46
EVs from micro electric vehicles, to passenger sedans, vans, buses and other
commercial vehicles.
Qingqing Xie et al. present a MATLAB/Simulink model for advanced vehicle
dynamic model for EV emulation, while taking into consideration actual
environmental conditions. The model also takes into account the rotational inertia of
each component involved in developing the model [28]. Another research published
in University of Washington discusses the dynamics of an electric vehicle by
preparing a model which uses enhanced techniques such as torque vectoring [29].
Similarly, another research uses modelica methodologies to model EV pickup
attributes to study the dynamic response of an electric vehicle [30]. Other such models
for battery dynamics and solar hybrid vehicles have been given in [31] and [32]
respectively. In conclusion, there is enough research material that can be found for
developing a model to study the vehicle dynamics of an electric vehicle.
Talking about solar electric vehicles, there is limited research present on the design of
solar electric vehicles, let alone, dynamic models of solar electric vehicles.
As outlined in [33] the research on solar electric vehicles can be divided into three
major segments a) commercial solar cars, b) solar electric vehicles for solar races and
c) small solar cars. Research groups and universities from all around the world take
part in solar car design for solar races such as World Solar Challenge [10] and
American Solar Challenge [11].
Talking about the second segment of solar electric vehicles, there are multiple
automakers, who have undertaken the task of designing and selling commercial solar
electric vehicles [12] [13] [14]. Finally some interesting designs have come forward
for the small solar electric vehicle segment as well [18] [20].
47
However, there exists a huge gap, when it comes to developing and studying a
dynamic model of a solar electric vehicle. In the previous chapter, we proposed a
design for a micro-solar electric vehicle for application in Pakistan [33]. In this
chapter, we are going to develop a dynamic model of our micro-solar electric vehicle
using MATLAB/Simulink.
3.3. Design of a Micro Solar EV
Before getting into the dynamic model of the micro solar electric vehicle, let us
briefly discuss the system design and PV sizing. The specifications of the vehicle used
in the design are as following;
Table 4: Vehicle Specifications used for the design [6]
Item Description
Max. Range 100 km
Dimensions 2450 mm*1350 mm*1750 mm
Wheelbase 1500 mm
No. of seats 3
Motor Size 1200 W
Total Motor Torque 100 Nm
Max Speed 43 km/hr
48
The design and PV sizing was carried out in HOMER Pro and the system can be seen
in the figure below:
Figure 17: System design of micro-solar electric vehicle in HOMER pro [6]
The sizing of the system was as follows:
Table 5: System sizing carried out in HOMER pro [33]
Item Quantity
Solar Panels/ Advance Solar Hydro Wind Power API –
150 W
3
24V, 1kWhr Li-Ion battery, 72V bus 3
Cost/NPC (Rs) 177013.7
Cost/COE (Rs) 54.62492
Cost/Operating cost (Rs/yr) 961.2305
Cost/Initial capital (Rs) 184128
System/Ren Frac (%) 100
49
Kyoc145/Capital Cost (Rs) 21000
Kyoc145/Production (kWh/yr) 766.9749
Dis1.0/Autonomy (hr) 57.6
Dis1.0/Annual Throughput (kWh/yr) 392.1335
Dis1.0/Nominal Capacity (kWh) 2.88
Based on this system design and sizing, a detailed dynamic model of the solar electric
vehicle was developed.
3.4. Dynamic Modeling of a Micro Solar EV
Electrical dynamic modeling is an important part of research and helps us understand
how a system would be working in real-life. A dynamic model of a PV system would
not only help us understand how the system would perform, but also how it would
reach to the changes in the environment. This dynamic model would also help us
simulate the system in various conditions that an electric vehicle has to go through
during its course of operation.
Figure 18 shows a block diagram of the dynamic model of the system. As shown in
the figure, the system consists of seven major blocks, which are further made of tens
of components, all coming together to form a dynamic model of our micro-solar
electric vehicle. The first block i.e. PV arrays generate power by converting solar
energy into electrical energy, which is then supplied to the DC-DC converter. This
converter is then connected to the battery storage block of our system, which not only
50
stores this power, but also supplies to the DC motor, when in operation. The battery
storage block can also be charged by an external AC source i.e. the electrical grid.
There are two control blocks used in the system, one is an MPPT controller, which
helps the system extract the maximum amount of power from the PV panels, and the
second one is a speed controller, which helps the DC machine operate at desired
speeds, as per the speed reference provided.
Figure 18: Block diagram of the dynamic model
3.4.1. PV Array
PV arrays are the most fundamental part of the dynamic model, as a micro solar
electric vehicle is being developed, meaning the focus is on extracting the most
amount of power from the PV array, given the available space to mount PV panels. It
is important to note that the non-linear output of PV modules is affected by
environmental parameters such as irradiance, temperature, clearness index, dust,
51
cloud and other shading effects etc. However, in this model, only irradiance and
temperature are being taken into account.
A PV array can be made up of multiple PV modules, which in turn consist of series of
PV cells. To better understand the performance of a PV module, let us take a look at
the equivalent circuit of a PV module as show in figure 19 [34].
Figure 19: Equivalent circuit of a PV module [34]
This equivalent circuit gives us some basic equations to help calculate the values of
current and voltages under consideration.
= exp
− 1
=
× ×
= +
= − −
52
In the above equations Eq. (1) to Eq. (4) [35], Id is the diode current, Iph is the
light-generated current, , I0 is the diode saturation current, VT is thermal voltage
equivalent, Vd is the diode voltage, Vpv and Ipv are module voltage and current,
respectively, K is the Boltzman constant equal to 1.3806×10−23 J/K, A is the
diode ideality factor, T is the cell temperature, q is the electron charge equal to
1.602×10-19 C, and Ncell is the number of cells connected in series in a module.
As evident, from equations 1 to 4, almost every parameter of the PV module is subject
to change as per the variations in temperature and irradiance.
Based on the results from HOMER Pro [33] the model consisted of three 24 V, 150 W
solar PV (Advance Solar Hydro Wind Power API – 150) modules connected in series,
making the bus voltage to be 72 V.
3.4.2. Maximum Power Point Tracking (MPPT) Controller
As discussed before, the performance of a PV module is very much dependent on
environmental factors like irradiance and temperature. For each PV module, there is a
point in the P-V curve, where the PV module is giving the maximum amount of
power. This point is called maximum power point, and it can be different for
different condition. This can be observed in figure 20, where two different
temperatures result in two different MPPs.
Figure 20: PV curve of our chosen PV module
53
Maximum power point tracking is a process, controls the power generation from a PV
panel in a manner that it is always operating at maximum power point. There are
numerous techniques to achieve maximum power point tracking such as incremental
conductance method, perturb and observe (P&O) method etc. In this model, the
perturb and observe (P&O) method is used, in order to implement maximum power
point tracking.
The way P&O technique is used is that a minor perturbation is introduced into the
system, which causes the power of the PV module to vary. After the perturbation is
introduced, the algorithm then observes the output power periodically and compares it
with previous power. A similar perturbation is introduced to vary the voltage of the
PV array. By doing so, the algorithm identifies, where the system is lying on the PV
curve. Depending on that, the duty cycle is either increased or decreased.
Figure 21: P&O algorithm working principle [34]
As seen in the figure 21, the system can have two operation points. The first one is
indicated as point 1 and the second one is indicated as point 2 on the graph. In the
54
case that the system was on point 1, the voltage needs to be increased. Similarly, if it
was on point 2, the voltage need to be decreased. In order to implement this operation,
we used a code-based function, according to the flowchart shown in figure 22.
The MPPT starts by measuring the current and voltage of the PV modules using
sensors, and outputs a duty cycle. This duty cycle is going to be used to generate a
PWM signal, which will enable or disable the switch used in our DC-DC converter. A
change in the duty cycle generated by the MPPT means that the voltage of the module
would change and subsequently, the power of the PV module would also change. The
P&O algorithm can be best described by the flowchart given in figure 22.
Figure 22: P&O algorithm flowchart
55
3.4.3. DC-DC Converter
As evident from the name, DC-DC converters are used where both the input voltage
and output voltage are in DC. The main purpose of using a DC-DC converter is to
produce a regulated voltage from an uncontrolled source to a load that may or may
not be constant, in a manner that is efficient. A DC-DC converter is a high-frequency
power conversion circuit, which makes use of high-frequency switching,
transformers, inductors, and capacitors.
There are many different topologies of DC-DC converter including buck, boost, buck-
boost and SEPIC converters. A buck converter is used in applications where the
output voltage needs to be lower than the input voltage, boost converter is used when
output voltage needs to be higher than input voltage, whereas, buck-boost and SEPIC
can be used in both situations. In this model, a buck converter is being used, since the
input voltage or PV module voltage in this case is higher than what is needed at the
battery terminal. Figure 23 shows the circuit of a buck converter.
Figure 23: DC-DC converter (buck converter) [36]
The buck converter operates in two steps. The first step of operation is when the
switch is turned ON. During this step, the current is flowing to the output capacitor,
thus charging it up. Since the voltage of a capacitor does not rise instantly, as well as
the inductor limiting the charging current, the capacitor voltage is not the full voltage
56
of the source during the switching cycle [36]. This is depicted in figure 24, the
highlighted part of the circuit shows the flow of current.
Figure 24: Buck converter operation (switch ON) [36]
During step two, the switch turns off and a voltage is created across the inductor due
to the fact that inductor cannot change current suddenly. This voltage allows the
capacitor to charge and power the load when switch is off [36]. This can be seen in
figure 25.
Figure 25: Buck converter operation (switch OFF)[36]
Now in order to design the buck converter, the values of the components used to form
the buck converter need to be calculated [37]. Following are the mathematical
equations that help design a buck converter.
=
()× ŋ (5)
Where, () = maximum input voltage
57
= output voltage
ŋ = efficiency of the converter
= × ( )
∆ × × (6)
Where,
= minimum switching frequency of the converter
∆= estimated inductor ripple current
∆=(0.1 0.4)× () (7)
= ∆
× ×∆ (8)
Where, = minimum output capacitance
∆ = desired output voltage ripple
∆ = × ∆ (9)
Where, ESR = equivalent series resistance of the used output capacitor [37].
The buck converter design is complete once the values for the inductance and the
capacitance to be used are calculated.
3.4.4. Li-Ion Battery
For the battery storage system of the PV system, a Li-Ion battery is used. The model
present in Simulink is called a generic battery model, which allows you to mimic the
charging and discharging characteristics of any rechargeable battery. Figure 26, shows
the equivalent circuit of the rechargeable battery model [38].
58
Figure 26: Equivalent circuit of a rechargeable battery model
The battery model has three observable parameters i.e. battery voltage, battery current
and SOC. As evident from the name, battery voltage is the rated voltage of battery. A
positive battery current represents that the battery is discharging, whereas a negative
battery current represents that the battery is charging. Similarly, SOC is the battery
state of charge, and gives information about the state of charge of the battery at any
given moment. An increasing SOC represents battery charging and a decreasing SOC
represents battery discharging.
3.4.5. AC-DC Charger
In addition to the battery being able to charge from the PV panels, the micro solar
electric vehicle would also have the ability to charge from an AC source, if needed.
This represents the time of the day when there is no sun, and the vehicle needs
charging. In such a case, the car battery could be directly plugged into an AC wall
outlet. This is where the AC-DC charging block comes in handy. Figure 27, shows the
equivalent circuit of an AC-DC charging block [39].
59
Figure 27: AC-DC charging block
3.4.6. DC Machine
Since the micro solar electric vehicle would be running a DC motor, in order to
develop the model of such a motor, we have used the DC machine block in Simulink.
The DC machine block allows us to implement both a wound-field or permanent DC
machine. However, in this case, a wound-field DC machine in series configuration is
being used.
The armature circuit of the DC machine consists of an inductor La and resistor Ra in
series with a counter-electromotive force (CEMF) E, which is proportional to the
machine speed.
= (10)
Where, is the voltage constant and is the machine speed.
ℎ == (11)
60
Where, is the torque constant.
There is a mechanical part of the DC machine, which is used to calculate the speed of
the machine from the net torque applied to the rotor.
= − − − (12)
Where, J = inertia,
= viscous friction coefficient, and
= Coulomb friction torque.
3.4.7. Speed Controller
The last block of the model is a speed controller, which is being used in order to
regulate the speed of the motor. The speed controller is a simple PWM Chopper
circuit. Figure 28, shows the model of the circuit
Figure 28: voltage to PWM signal converter block
By taking into account the reference voltage set on the input side of this circuit, it
generates a PWM signal, which operates a high-frequency switch thus changing the
average value of current supplied to the motor, which results in an increase or
decrease in the motor speed as required.
61
3.5. Simulation Results and Discussion
A dynamic model of the block diagram shown in figure 18, was implemented in
Simulink, which consisted of all the major blocks discussed in the previous section.
The detailed model can be seen in figure 29.
3.5.1. PV Operation
Now let us take a look at the results of each part of the simulation. First one is the PV
array, the output of which is very much dependent on the irradiance values. A variable
irradiance curve was fed into the PV model, to see how PV output varies accordingly.
Figure 30, shows the changing irradiance values. At these values, the PV is generating
the amount of current and voltage shown in figure 31. Notice, how the voltage and
current values change with the irradiance values.
Figure 29: Simulink model of the proposed micro solar electric vehicle
62
3.5.2. Battery Operation
Now let us move on the battery parameters, when PV modules are in operation and
actively generating power, this power is being directly transferred and deposited into
the battery. This is being demonstrated in figure 32. Notice that the SOC of the
battery is increasing over the course of the simulation, and the battery current is in
negative, which shows the influx of current into the battery.
Similarly, when the PV is disconnected due to any reason including bad weather or
absence of sun during night time, the PV panels will not be producing any power.
Hence, the EV motor will be drawing power from the battery. Looking at figure 33, it
can be seen that the SOC of the battery is decreasing and the battery current is also
positive, which shows the outflow of current from the battery.
In the last scenario, the battery is being charged directly from the AC source, through
the CCCV charging block. In this scenario, once again the battery SOC is positive and
the battery current is in negative as shown in figure 34.
3.5.3. DC-Machine Operation
In this section, the operation of the DC machine will be discussed, which represents
the electric vehicle motor. The DC machine operation can be observed in two
different modes.
The first one is the normal mode, in which the DC machine is drawing power from
the battery and generating a normal response. This can be seen in figure 35, from the
armature current, field current and electrical torque values.
The second mode of operation is when the DC machine is put in reverse, which
represents the electric vehicle moving in reverse direction. In a DC series machine, in
63
order to reverse the direction of motion, the polarity of field windings needs to be
changed. In this model, that is achieved by using ideal relay modules, which can be
switched at any instant at the start of, or during the simulation to reverse the direction
of the vehicle. Figure 36 shows the vehicle direction changing at the 5 second mark
during the simulation. This change is denoted by a change in the direction of field
current.
3.5.4. DC-Machine Operation Under Variable Load
In order to understand the response of the electric vehicle over uneven or steep roads,
the simulation is run for 60 seconds, a variable load profile is introduced and the
impact on the dynamics of the electric vehicle is observed. Figure 37, shows the
dynamic load profile used in the simulation. Figure 38, shows DC Machine dynamics
under that changing load profile. The electrical torque and armature current of the
DC-machine varies accordingly to keep up with the uneven roads.
3.5.5. Speed Control
The final step is understanding how the speed control circuit works. In this case, the
simulation is run for 60 seconds, a signal which changes the speed reference every 10
seconds is introduced, and the impact on dynamics of the electric vehicle can be
observed Figure 39, shows the changing speed reference. Figure 40, shows the
dynamic response of the DC-machine to keep up with the changing speed reference.
64
Figure 30: Variable irradiance values to measure PV response
Figure 31: PV voltage and current variance as per changing irradiance
65
Figure 32: Battery charging mode (from PV modules)
Figure 33: Battery discharging mode (during motor operation)
66
Figure 34: battery charging mode (from AC source)
Figure 35: DC machine normal operation
67
Figure 36: DC machine forward and reverse operation
Figure 37: Variable load profile for DC machine
68
Figure 38: DC machine dynamics under variable load
Figure 39: Variable speed reference for DC machine
69
Figure 40: DC machine dynamics under variable speed reference
3.6. Conclusion
A novel design for a micro solar electric vehicle for application in Pakistan has been
presented in this paper. Not only does this micro solar electric vehicle provide the
basis for the design of a new class of cars, but it also helps solve almost all of the
problems that are currently slowing the growth of EV market share in Pakistan and
other developing countries.
The said micro solar electric vehicle was designed in HOMER Pro, and a system
sizing was done. According to this system sizing, the micro solar electric vehicle
would require 3, 24 V, 150 W PV modules (Advance Solar Hydro Wind Power API –
150) to add a range of approximately 30 KMs to the pre-existing battery range of the
electric vehicle.
The electric vehicle can also be charged from a 220 V AC outlet with the help of the
onboard AC-DC charging block, which allows the electric vehicle to charge at
70
extremely low currents, easily supported by the current residential electricity
infrastructure in Pakistan.
In addition, a dynamic model of the micro solar electric vehicle was developed to be
studied in much more details. The dynamic model focused on three different aspects
of the systems i.e. power generation by PV modules that are to be mounted on top of
the vehicle, battery charging from PV modules as well as an external AC source, and
finally DC-motor operations in forward and reverse mode. Other notable features of
the model include a maximum point power tracker and a PWM chopper based speed
control circuit.
The dynamic model of the system not only helped us fully understand the working of
the system in different modes, conditions and situations, but also helped us understand
how the system will react to any variations in the environmental factors such as
irradiance and temperature etc.
71
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https://digital.lib.washington.edu:443/researchworks/handle/1773/40251
[30] “Electric Vehicle Dynamics Simulations: Modelica Methodologies,” Modelon,
May 28, 2020. https://www.modelon.com/electric-vehicle-dynamic-simulation/
(accessed May 04, 2022).
[31] O. Tremblay, “Experimental Validation of a Battery Dynamic Model for EV
Applications,” E´cole de Technologie Supe´rieure, Stavanger, Norway, 2009.
[32] L. Bai, Y. Zhang, H. Wei, J. Dong, and W. Tian, “Digital Twin Modeling of a
Solar Car Based on the Hybrid Model Method with Data-Driven and
Mechanistic,” Applied Sciences, 2021, doi: 10.3390/APP11146399.
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[33] A. Husnain, “System Design and PV Sizing of a Micro Solar Electric Vehicle
for Pakistan,” presented at the 9th IEEE Conference on Technologies for
Sustainability (SusTech 2022), Sunny Riverside, CA, Apr. 2022.
[34] M. Mousavi and M. T. Iqbal, “Design and Dynamic Modelling of a Hybrid
PV-battery System for a House with an RO Water Desalination Unit in Iran,”
European Journal of Electrical Engineering and Computer Science, vol. 5, no. 6,
Art. no. 6, Dec. 2021, doi: 10.24018/ejece.2021.5.6.370.
[35] B. Jiang and M. T. Iqbal, “Dynamic Modeling and Simulation of an Isolated
Hybrid Power System in a Rural Area of China,” Journal of Solar Energy, vol.
2018, p. e5409069, Jun. 2018, doi: 10.1155/2018/5409069.
[36] A. Castaldo, “Switching Regulator Fundamentals.” Texas Instruments, Feb.
2019.
[37] A. Castaldo, “Basic Calculation of a Buck Converter’s Power Stage.” Texas
Instruments, Aug. 2015.
[38] “Generic battery model - Simulink.”
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(accessed May 05, 2022).
[39] “Constant-current constant-voltage battery charger - Simulink.”
https://www.mathworks.com/help/physmod/sps/powersys/ref/cccvbatterycharger.
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[40] “Pakistan Household Income per Capita, 2005 – 2022 | CEIC Data.”
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capita (accessed Jun. 09, 2022).
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CHAPTER 4: INSTRUMENTATION AND CONTROL
DESIGN FOR A MICRO SOLAR ELECTRIC VEHICLE
4.1. Introduction
In this chapter, the design of instrumentation and control for a micro-solar electric
vehicle is presented. The instrumentation and control circuit of our micro solar
electric vehicle utilizes a small microcontroller to monitor, control and operate a set of
electronics such as headlights, turn signals, speedometer etc. While in most modern
vehicles, instrumentation and control can be very complex, since they come equipped
with hundreds if not thousands of features.
In the case of the micro-solar electric vehicle designed as a part of this research, one
of the goals is to keep the price point of the vehicle affordable and in reach of the
target demographics. Therefore, most luxury features can be skipped and only
features necessary for the safe operation of the car are to be added.
4.2. Choice of Design Tool
In order to design instrumentation and control circuit for the micro solar electric
vehicle, Tinkercad will be used. Tinkercad is a web-based software application that
breaks down highly complicated circuit drawings and 3D models into easy to design
layouts. The software allows designers to choose components from a library of pre-
existing components, instead of having to design the components from the scratch.
The software also has a library of various microcontrollers, that can be used along
with other components and code can be embedded into it. Tinkercad provides a live
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simulation view of all the circuits designed in it, thus eliminating the need to
implement the circuit with hardware.
4.3. Design Principle
In order to understand the design of the instrumentation and control circuit for the
micro solar electric vehicle, let us first try to come up with a general idea of what the
circuit should be. The way instrumentation and control circuit works in a car, is that
every single electronic component in a car comes with its own set of controls. These
controls require human input from the driver, for when they are to be used. For
instance, if the driver were to turn on their right turn signal, they will have to push a
lever or a slider switch and give the input to the microcontroller to make that happen.
The microcontroller would then operate the relay, which then turns that component on
for as long as the user input is there.
Let us take a look at a block diagram of the control and monitoring circuit as well as
the auxiliary circuitry for the micro solar electric vehicle.
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Figure 41: Block diagram for control and monitoring circuit for micro solar electric
vehicle
Figure 42: Block diagram for auxiliary circuitry for a micro-solar electric vehicle
77
Figure 41, shows the block diagram for control and monitoring circuit for the micro
solar electric vehicle, whereas figure 42, shows the block diagram of the auxiliary
circuitry for the vehicle.
4.4. Major Components
4.4.1. DC-DC Converter
When building the instrumentation and control circuit for a vehicle, one important
consideration is how to power the on-board computer and all the auxiliary
components like headlights, taillights etc. There are two different approaches being
undertaken by automobile manufacturers. First one is by making use of a separate 12
V battery in order to supply power to the auxiliaries. The second approach is popular
amongst electric vehicles, which usually have a high voltage battery to power the
electric motor. This approach makes use of a DC-DC converter in order to lower the
voltage supply from the primary battery and make it suitable for use in the auxiliary
components. Similarly, this approach is once again needed when giving power supply
to the micro-controller used in the on-board computers. While most auxiliary
components such as headlights, horn, turn signals etc. operate at 12 V, the
microcontroller usually operates at 5 V. Therefore, once again a converter is used to
step down the voltage from 12 V to 5 V. The first approach, which uses a separate 12
V battery, requires the use of a separate charging system which charges the 12 V
battery. Since, in this case, a low price point was one of the desired outcomes, the
second approach is more suitable, as this way the use of a separate battery and a
charging system can be avoided.
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Figure 43 shows a block diagram of the main power stage of the micro electric
vehicle. The block diagram shows how two DC-DC converters are utilized in the
main power stage of the vehicle. The 72 V power supply is stepped down to 12 V
with the help of a DC-DC converter #1 to power all the auxiliary components of the
circuit, and this 12 V supply is further stepped down to 5 V with the help of DC-DC
converter #2 to power the micro-controller.
Figure 43: Block diagram for main power stage of the vehicle
4.4.2. LCD Display
LCD display is an important component of the control and monitoring circuit.
Throughout the operation of the micro solar electric vehicle, there are multiple
sensors and measurement modules, which will be monitoring the data in real-time.
This real-time data needs to be displayed in order for the user to be aware of the state
that the vehicle is currently in, and then provide input accordingly. Figure 44, shows
the LCD display, which is to be utilized in the circuit. Some of the important data
displayed on the LCD includes RPM, speed, distance, battery voltage, battery state of
charge, PV voltage, and PV output power.
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Figure 44: LCD used to display real-time data
4.4.3. Forward/Reverse Control
The first major component of the control circuit is the forward/reverse lever, which
allows the car to move in the forward or reverse direction. The forward and reverse
control has been implemented by making the use of a slide switch, which is connected
with a DC motor. When the slide switch is in Forward position, it would allow the
current to flow to the motor’s field windings in a normal manner, so as to allow it to
drive the car forward. When the slide switch is in reverse direction, it would change
the wiring connections in such a way, that the polarity across the field windings of the
motor is reversed, which allows the motor to run in a reverse direction. This change of
polarity is achieved by making the use of four high current relays, as demonstrated in
the dynamic model of the vehicle, discussed in previous chapter.
4.4.4. Speed Control
The second most important block in the control circuit is the use of speed control. The
speed control allows the motor speed to be increased or decreased as per user
requirements in real time. Referring to the dynamic model of the micro solar electric
vehicle, which was developed in the previous chapter, the speed control was an
essential part of the model. In the dynamic model, the speed control mechanism was
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implemented with the help of a simple PWM Chopper circuit. However, in this
circuit, the implementation has been made with the help of a potentiometer, which
limits or increases the current flowing to the motor in order to increase or decrease its
speed. Both of these speed control methods use a very similar technique, which is to
limit the amount of current flowing to the motor.
4.4.5. RPM Meter
Next major components of the circuit are being used to perform monitoring tasks. The
first one being the RPM meter. RPM measurements can be taken in a variety of ways.
The device used to measure RPM is called a tachometer, which can be made up of
either a laser sensor, proximity sensor, optical sensor or even shaft encoders. In this
circuit, the RPM data can be extracted directly from the motor with the help of the
microprocessor and without using any sensor. The data is in revolutions per minute
and can be directly displayed on to the LCD screen in the dashboard.
4.4.6. Speedometer
After the RPM data has been recorded, it becomes fairly easy to calculate the speed of
the car. The microprocessor records the RPM values and then converts them into
Km/hr values. The radius of the car wheels is also an important factor in determining
the current speed of the car. The speed data is then also displayed along with the RPM
in the dashboard.
4.4.7. Odometer
The Odometer of the car shows the total amount of mileage that the car has covered.
The distance covered can be calculated from the speed data of the car and the amount
of time that the car has been running for. An important feature of the odometer is that
not only should it constantly update the distance traveled, but also retain its reading
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even when the battery is turned OFF. To do that, the odometer uses what is called a
programmable read-only memory or PROM. With the help of PROM, each time a
new reading is recorded, it permanently replaces the old reading. This reading is now
stored in the memory indefinitely without the need for a battery. The distance data is
also displayed in the LCD display on the dashboard.
4.4.8. Battery Voltage & SOC
Most internal combustion engine cars display the fuel level in the car’s fuel tank on
the dashboard as an important indicator for the user to know when to fill-up. Since,
electric cars do not use fuel, indicators like battery voltage and battery state-of-charge
are important indicators, which allow the users to know when to charge the battery of
the car. A measurement block is used alongside the battery, which extracts all
important data from the battery including battery voltage and state of charge. Then
with the help of the microcontroller, it is displayed in the LCD on the dashboard.
4.4.9. PV Voltage & Output Power
Since this is a micro-solar electric vehicle, throughout the design, the main focus has
been on charging the car’s battery from solar power. In order to achieve this, solar
modules were mounted on the car’s roof. This makes it essential for a monitoring
circuit to be present on-board the car, which provides the user with all the necessary
information regarding the solar modules. A voltage/current measurement block is
connected to the PV modules, which provides the PV module voltage and current
values. Using these two values, the microcontroller can calculate the output power of
the module. Thus PV module voltage and output power can be displayed in real-time
on the dashboard.
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4.4.10. Headlights
Next is the auxiliary circuit for the micro solar electric vehicle. The first major
component of the auxiliary circuit the 12 V headlight bulbs. The headlights are a
crucial part of a vehicle in maintaining visibility during night time. Most headlights
are either halogen bulbs or LED lights that require a 12 V battery supply. The
headlights are turned ON and OFF using a relay, which isolated the 12 V system from
the 5 V system at which the microcontroller is operating. After obtaining input from
the user, the microcontroller sends the signal to the relay, which then operates the 12
V circuit thus turning on the headlight bulbs.
4.4.11. Turn Signals
The second function being performed by the auxiliary circuitry is the left and right
turn signals. Turn signals are blinking lights that are used as indicators for other
vehicles, when a driver wants to take a turn on the road. Turn signals are usually
yellow/orange in color. In this circuit, orange 12 V LED bulbs for the four turn
signals of the car and two turn signal indicators in the dashboard were used. For the
turn signals to function, the microcontroller sends a signal to the relays, which then
operate the 12 V circuit thus turning on the turn signals.
4.4.12. Hazard Lights
Next up, the vehicle needs to have emergency/hazard lights which are red 12 V LED
bulbs that blink at regular intervals to alert the approaching vehicles, in case there is
an emergency on the road.
4.4.13. Taillights
Another fundamental function of the auxiliary circuit is rear taillights. Taillights are
red 12V LED bulbs that turn ON on two different occasions. One is when the driver
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applies the break, and the second is during night when the headlights are ON. In this
case, taillights are used to alert the vehicles approaching from behind that there is a
vehicle on the road. Taillights are also operated using relays, which are triggered by
the microcontroller.
4.4.14. Horn
The vehicle also needs to have a 12 V audio horn that is used to alert other drivers.
The horn is operated when the user gives an input to the microcontroller, which sends
a signal to the relay. The relay then operates the 12 V horn.
4.4.15. Windshield Wipers
Last but not least, windshield wipers are also a part of the circuit, The windshield
wipers make use of small 12 V servo motors in order to do a half rotation to clean the
windshield of the car, and improve visibility for the passengers. The servo motor used
in the windshield wipers is a 12 V motor, operated by a relay, which is triggered when
the microcontroller sends a signal to the relay.
4.4.16. User Interface
Figure 45, shows the user interface for the control, monitoring and auxiliary circuit of
the micro solar electric vehicle. All of the above discussed major functions can be
seen in the user interface. The upper rectangle of the image shows the dashboard,
where values of different parameters will be visible, whereas, the lower rectangle
shows the input panel, where human input will be registered.
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Figure 45: UI for micro solar electric vehicle
4.5. Tinkercad Model
Figure 46, shows a simplified Tinkercad model of the control and monitoring circuit
of our micro solar electric vehicle.
Figure 46: Tinkercad model of control and monitoring unit
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The model shown in figure 46 implements all of the control and monitoring functions
shown in figure 41 and discussed in the section above. The human input can be
registered with the help of the various switches as shown in figure 46. PV and battery
voltages and current are measured with the help of voltage/current measurement
circuits. These values are then sent to the microcontroller, which then after all the
required calculations displays them on the LCD screen. The microcontroller also
sends signal to relays in order to perform any task that the user defines, whether it is
increasing or decreasing the motor speed or putting the motor into forward/reverse
mode.
Figure 47, shows a simplified Tinkercad model for the auxiliary circuit of the micro-
solar electric vehicle.
Figure 47: Tinkercad model of the auxiliary circuit
The Tinkercad model shown in figure 47 corresponds to the block diagram shown in
figure 42 in the start of the chapter. This circuit performs all the tasks when it comes
to operating the auxiliary electronics such as headlights, turn signals etc. As discussed
in the previous sections, all the components used in this model are 12 V components,
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whereas the microcontroller is a 5 V electronic. Therefore, it cannot directly turn ON
and OFF a 12 V component. In order to do perform that task, relays are utilized
throughout the circuit. The human input once again is registered through the switches
shown in figure 6. Based on the input registered, the microcontroller then sends a
signal to the relay to turn ON the corresponding electronic whether it is a 12 V
headlight bulb, a 12 V horn, or a 12 V DC servo motor for the windshield wipers.
4.6. Conclusion
The Tinkercad models shown in figure 46 and figure 47, mark the successful design
of a complete instrumentation and control system of the micro solar electric vehicle to
be designed. The instrumentation and control system is divided into two major parts,
first one being the monitoring and control circuit, which not only monitors all the
essential parameters that a user needs to be aware of while driving the vehicle, but
also provides all the important controls such as braking, forward and reverse control
etc. The second part of the system is the auxiliary circuit, which basically includes all
the features of the car that are necessary for its safe operation. These include
headlights, turn signals, emergency lights, taillights, horn, windshield wipers etc.
Tinkercad being a comprehensive design tool, helps design models that can be
converted into functioning hardware systems with very little to no modifications. The
Tinkercad model also enlists all the components that are to be used, when making a
hardware model of the system. It also comes with wiring schematics, which can be
used a wiring guide when connecting the different components on the hardware
model. The Arduino code that was used in the Tinkercad model can be loaded onto
the Arduino used in the hardware model in order to control all the associated
components. The wiring schematics are attached in the Appendix section.
87
CHAPTER 5: CONCLUSION AND FUTURE
WORK
5.1. Conclusion
The global transport sector is responsible for the third largest sector wise emissions
and is a huge cause for concern, for governments and organizations fighting climate
change worldwide. Almost all of these stakeholders have realized that electric
vehicles are the future of transportation and are actively taking steps to increase the
rate of adoption of electric vehicles. Automobile companies around the world,
especially in most developed countries have laid out there EV strategies in which they
plan on converting their entire fleets of vehicles to electric vehicles by either 2030 or
soon after.
Until that happens, EV adoption and affordability has a number of challenges in its
way. These challenges are further amplified when the discussion is about developing
countries like Pakistan. In today’s modern world, where electricity is a basic needs,
Pakistan still struggles to meet the electricity demands of its residential, commercial
and industrial sectors. This energy landscape poses a huge challenge to the
mainstream adoption of electric vehicles throughout the country. The shortfall of
electricity not only means that the power is not available 24/7 but it also means the
cost of electricity being on a continuous rise, thus pushing the EV affordability further
out of the reach of the general public.
In today’s market (2022), when the price of electric vehicles starts anywhere from
40,000 USD and can go all the way up to 100,000 USD, being able to purchase an EV
88
is a challenge even for someone living in the developed part of the world, where
average income is relatively high. In comparison, Pakistan’s average household
income is even lower, approximately 587.069 USD in 2019 [40], which means
people are simple unable to afford a new electric vehicle from the legacy automakers.
Moreover, lack of charging infrastructure is a problem that has been recognized
globally, and is a common cause for concern amongst new EV buyers. This is also
referred to as range anxiety. In order to overcome this, there is need for widespread
availability of commercial charging infrastructure. However, in the case of Pakistan,
once again this challenge is amplified due to the economic constraints. Not only does
Pakistan lacks a commercial charging infrastructure of any kind, the residential
electrical infrastructure in the country is also unable to support EV charging. The
electricity supply from utility companies is usually 220V at 5 or 10A at most, which is
insufficient to charge any electric vehicle at a reasonable speed.
All these issues presented a huge gap in the market as well as the research world, thus
creating an opportunity to pursue this research.
To start, a comprehensive literature review was conducted in which all the problems
facing the EV adoption across the world and in Pakistan were identified. The review
also included looking for solutions to overcome these problems. While the long-term
solution is to build a more reliable and powerful electrical infrastructure in the
country, it does not seem to be happening anytime soon. Thus starts the search for a
more feasible solution. The use of micro solar electric vehicles seemed like a
promising solution to the problems at hand.
Once again a deep look was taken in to all the research present on the topic of micro
electric vehicle, their design, sizing and modeling etc. The review showed that there is
89
a huge gap in the research present on the topic. The design of solar electric vehicles
can be majorly categorized into two different categories; solar race cars, and
commercial solar cars. The first category does not satisfy even the basic requirements
of what a road legal vehicle should be and the second category is in very early stages
of development. Therefore, the motivation to undertake the design of a micro solar
electric vehicle increased.
Since the design of the solar electric vehicle that is being undertaken is for application
in Pakistan, the data that is to be utilized in designing and running the model needs to
be from Pakistan. Therefore, solar irradiance data and daily average temperature data
was collected from a city called Bahawalpur, located in the Southern Punjab region of
Pakistan.
After data collection, HOMER Pro was used to not only build a system design and do
PV sizing for the micro solar electric vehicle, but also to carry out a techno-economic
feasibility analysis of the designed system. To decide upon the EV design to be
utilized in this research, some baseline values were required for example the
dimensions of the car, weight of the car, motor power, no. of passengers, average
speed etc. For this purpose, a commercially available and economical electric vehicle
called Chang Li Electric vehicle was used. Chang Li is an electric vehicle being
manufactured by a Chinese EV automaker and can be easily imported to Pakistan and
that too at an economical price point. Based on these baseline values, HOMER Pro
simulated a model of the micro electric vehicle which can then be used to design the
micro solar electric vehicle. The model specified the number of solar modules and
batteries that were to be utilized in order to meet the load demand, if the car were to
travel a set distance. The model also provided all relevant cost information including
capital cost, maintenance cost, NPC cost etc.
90
Once the PV sizing of the micro solar electric vehicle was complete, a dynamic model
of the vehicle could be built. In order to that, Simulink was used. Simulink is a
comprehensive modeling tool, which allows the design, simulation and modeling of a
variety of systems. For the dynamic model of the vehicle, the parameters outlined by
the HOMER Pro software were used. The dynamic model consisted of a number of
different blocks from solar modules, MPPT, to DC-DC converters, Li-Ion battery
model, on-board AC-DC charger, DC Motor, and a PWM Chopper based speed
control circuit. Once the model was complete, it was used to run tests for a variety of
different scenarios that the micro solar electric vehicle might encounter when being
used in real life. These scenarios included the power generation by solar PV modules
under variable irradiance values, charging of battery from different source i.e. PV
modules and AC outlet, discharging of battery to run the DC motor, DC motor
operation in forward/reverse mode, DC motor operation under variable load
conditions i.e. uneven roads, DC motor operation under variable speed conditions i.e.
the use of accelerator by the driver. All these test gave successful results i.e. the micro
solar electric vehicle behaved as expected under all the above mentioned conditions.
Finally, the design of an instrumentation and control system for the micro solar
electric vehicle was also presented. As with any road legal vehicle, there are a set of
features that the vehicle must have in order to ensure its safe operation. These features
include everything from accelerator, brakes, forward/reverse control, different
indicators in the dashboard, turn signals, headlights, emergency lights etc. To carry
out the design of the instrumentation and control system of the car, a software called
Tinkercad was used. Tinkercad is a basic design software which allows the design of
simple to complex ready to build circuit designs. It provides a comprehensive wiring
schematic, which can then be used to build the hardware of the circuit. The design
91
was divided into two different parts; first part being the control and monitoring of the
micro solar electric vehicle, and the second part being the auxiliary circuitry of the
vehicle.
The contributions of this thesis are listed below:
Identification of the challenges to EV adoption in the global context as well as
the context of developing countries like Pakistan.
Gap analysis of both academic and industrial research on the use of on-board
solar PV modules to power electric vehicles.
System design and PV sizing of a micro-solar electric vehicle based on the 3
passenger Chang Li electric vehicle for application in Pakistan.
Dynamic modeling of a micro solar electric vehicle, including PV to battery
charging, AC source to battery charging, maximum power point tracking, and
the operation of DC motor under variable loads and speeds.
Design of a ready to build, instrumentation and control system for a micro
solar using Tinkercad with all the monitoring, control and auxiliary electronics
along with detailed wiring schematics.
5.2. Future Work
While the research presented in this thesis focused on the design of a micro solar
electric vehicle, the innovative design approach used is highly multi-faceted and can
be used for a number of different applications. Moreover, there are a number of things
that can be further investigated in the design and analysis of a micro solar electric
vehicle to ensure that the design can easily be translated into reality.
92
1. Firstly, the resources used for the PV design and system sizing of the micro-
electric vehicle were specific to Pakistan and a region of Pakistan, called
Bahawalpur to be precise. This region had excellent solar irradiance
throughout the year and thus provided an ideal situation for the micro-solar
EV to be driven in. It would be worthwhile to investigate the feasibility of the
electric vehicle in different conditions, perhaps in areas with less sun
throughout the year. This could have some implications on the PV design and
system sizing of the car as well.
2. Secondly, vehicle dynamic modeling is a vast field and there is a huge number
of factors that can be considered in order to make the dynamic model as
accurate as possible. These factors could involve acceleration and braking
characteristics, body design of the vehicle, passenger weight, passenger
driving behavior, suspension characteristics, drag produced by tires etc.
3. As mentioned above, the design approach is versatile and can be applied to a
number of different applications for example the design of golf-carts, auto-
rickshaws, agricultural equipment, commercial fleets etc.
93
Appendix A
Wiring Schematics
Figure 48 shows the wiring schematics for the control and monitoring circuit. The
wiring guide can be used to connect components when making a hardware model of
the system.
Figure 48: Wiring schematics for control and monitoring circuit
Figure 49, 50, and 51 show the wiring schematics for the auxiliary circuitry of the
micro solar electric vehicle. This wiring schematic can be used as a wiring guide
when making the hardware model for all the auxiliary circuitry of the vehicle.
94
Figure 49: Wiring schematic for auxiliary circuitry Part 1
Figure 50: Wiring schematic for auxiliary circuitry Part 2
95
Figure 51: Wiring schematic for auxiliary circuit Part 3
96
Appendix B
Arduino Code for Control Circuit
#include <LiquidCrystal.h>
// initialize the library with the numbers of the
interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
int A;
int B;
float C;
int Analog = 0;
float Voltage = 0;
float SOC = 0;
int Analog1 = 0;
float Voltage1 = 0;
float SOC1= 0;
float aa = 9;
void setup() {
// set up the LCD's number of columns and rows:
pinMode(A0, INPUT);
pinMode(A1, INPUT);
pinMode(A2, INPUT);
lcd.begin(16, 2);
}
void loop() {
lcd.setCursor(0, 0);
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lcd.print(map(analogRead(A0), 0, 1023, 0, 5000));
lcd.print("RPM ");
lcd.setCursor(8, 0);
A = map(analogRead(A0), 0, 1023, 0, 5000);
B = 0.1885*A*0.254;
lcd.print(B);
lcd.print("Km/Hr ");
lcd.setCursor(3, 1);
A = map(analogRead(A0), 0, 1023, 0, 5000);
B = 0.1885*A*0.254;
C = B*((millis()*0.01)/3600);
lcd.print(C);
lcd.print("Km ");
delay(10000);
lcd.setCursor(0, 0);
lcd.print(" ");
lcd.setCursor(0, 1);
lcd.print(" ");
delay(5000);
lcd.setCursor(0,0);
lcd.print("VOLTS : ");
lcd.setCursor(13,0);
lcd.print("V");
Analog = analogRead(A1);
Voltage = ((Analog / 1023.0) * 5)*3.75;
lcd.setCursor(8,0);
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lcd.print(Voltage);
SOC = Voltage*(0.1);
lcd.setCursor(0,1);
lcd.print("Power: ");
lcd.setCursor(7,1);
lcd.print(SOC);
lcd.setCursor(10,1);
lcd.print(" W");
delay(3000);
lcd.setCursor(0, 0);
lcd.print(" ");
lcd.setCursor(0, 1);
lcd.print(" ");
delay(3000);
lcd.begin(16,2);
lcd.setCursor(0,0);
lcd.print("VOLTS : ");
lcd.setCursor(13,0);
lcd.print("V"); Analog1 = analogRead(A2);
Voltage1 = ((Analog / 1023.0) * 5)*3.75;
lcd.setCursor(8,0);
lcd.print(Voltage1);
SOC1 = (Voltage1/aa)*100;
lcd.setCursor(0,1);
lcd.print("SOC: ");
lcd.setCursor(5,1);
lcd.print(SOC1);
lcd.setCursor(9,1);
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lcd.print(" %");
delay(3000);
lcd.setCursor(0, 0);
lcd.print(" ");
lcd.setCursor(0, 1);
lcd.print(" ");
delay(3000);
}
Arduino Code for Auxiliary Circuit
// C++ code
//
#include <Servo.h>
Servo servoBase;//Asigno un nombre específico
int R_blinker = 0;
int L_blinker = 1;
int F_headlight = 2;
int B_taillight = 3;
int horn = 4;
int Emergency = 5;
int In_R_blinker = 6;
100
int In_L_blinker = 7;
int In_F_headlight = 8;
int In_B_taillight = 9;
int In_horn = 10;
int In_Emergency = 11;
void setup()
{
pinMode(0, OUTPUT);
pinMode(1, OUTPUT);
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, INPUT);
pinMode(7, INPUT);
pinMode(8, INPUT);
pinMode(9, INPUT);
101
pinMode(10, INPUT);
pinMode(11, INPUT);
servoBase.attach(A1);//Pin a utilizar para servo
servoBase.write(0); //asigno 0 al servo motor
}
void loop()
{
for(int i=0; i<=180; i=i+10)
{
servoBase.write(i);
delay(100);
}
if(digitalRead(In_R_blinker) == 1)
{
digitalWrite(R_blinker, HIGH);
}
else{
102
digitalWrite(R_blinker, LOW);
}
if(digitalRead(In_L_blinker) == 1)
{
digitalWrite(L_blinker, HIGH);
}
else{
digitalWrite(L_blinker, LOW);
}
if(digitalRead(In_F_headlight) == 1)
{
digitalWrite(F_headlight, HIGH);
}
else{
digitalWrite(F_headlight, LOW);
}
if(digitalRead(In_B_taillight) == 1)
{
digitalWrite(B_taillight, HIGH);
103
}
else{
digitalWrite(B_taillight, LOW);
}
if(digitalRead(In_horn) == 1)
{
digitalWrite(horn, HIGH);
}
else{
digitalWrite(horn, LOW);
}
if(digitalRead(In_Emergency) == 1)
{
digitalWrite(Emergency, HIGH);
delay(1000);
digitalWrite(Emergency, LOW);
delay(1000);
}
else{
104
digitalWrite(Emergency, LOW);
}
}
105
List of Publications
1. A. Husnain, M. T. Iqbal, “System Design and PV Sizing of a Micro Solar
Electric Vehicle for Pakistan.” Presented at the 9th IEEE Conference on
Technologies for Sustainability (SusTech 2022), Sunny Riverside,
California
2. A. Husnain, M. T. Iqbal, “Dynamic Modeling of a Micro Solar Electric
Vehicle for Pakistan using Simulink.” Presented at the IEMTRONICS
2022 (International IOT, Electronics and Mechatronics Conference),
Toronto, Canada.
3. A. Husnain, M. T. Iqbal, “Design and Simulation of a Solar Parking
System to meet all Energy needs of 10 Electric Cars.” Presented at The
30th Annual Newfoundland Electrical and Computer Engineering
Conference (NECEC 2021), St. John’s, NL.
