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Chebyshev polynomials based compensator design via higher order sinusoidal input describing functions in traction motor drive to improve performance of electric vehicle
Abstract
In electric vehicles (EVs), the efficient selection of the basic elements and the control of the electric motor and the overall system is vital to extend the performance of the vehicle. A feedback control loop with proportional-integral (PI) controllers is usually used in the control of electric motors. Within the scope of this study, the system is handled with frequency-based methods and it is aimed to reduce the performance degrading effect on the system output. In this study, Higher Order Sinusoidal Input Describing Functions (HOSIDFs) are used in order to improve the performance of EVs. Here, the EV is modeled as a Lur’e-type system and a compensator is designed within the PI speed control loop of the electric motor by using Chebyshev polynomials. The optimal coefficients of the Chebyshev polynomials-based compensator minimize the cost function which is related to the harmonics of the system output. This work introduces a novel approach for controlling the traction motor of EVs using a frequency-based method through HOSIDFs. The objective is to enhance the performance of the drive system. Throughout this study, it is also aimed to improve the consumption of the battery and passenger comfort. The results and success of the proposed method are illustrated in time-domain and harmonic plots.
The state of charge (SOC) of the battery is an important basis for the battery management system to perform state monitoring and control decisions. In this paper, by identifying the internal parameters of the battery model at different temperatures and SOCs of the lithium-ion battery, the specific factors that affect the change of the parameters are analyzed, the segmentation basis of the model and the fitting method of related parameters are discussed, the second-order equivalent circuit model of the lithium-ion battery whose parameters vary with SOC and temperature is established, the unscented Kalman filter (UKF) is used to estimate the SOC of the lithium-ion battery, and an improved SOC estimation method based on optimized equivalent circuit model is proposed. Simulation and experimental results show that the improved SOC estimation strategy can obtain high estimation accuracy in a wide temperature range.
In this paper, battery electric vehicle (BEV) controllers are smartly tuned with particle swarm optimization (PSO) and genetic algorithm (GA) to ensure good speed regulation. Intelligent tuning is ensured with a proposed and well-defined cost function that aims to satisfy the design requirements in terms of minimum overshoot, fast response, and tolerable steady state input. Two proposed cost functions are formulated for both simple speed input and for driving cycles. The BEV is controlled with the field oriented control technique (FOC), and it is driven by a permanent magnet synchronous motor (PMSM). An efficient control scheme based on FOC is built using a simplified closed loop control system including BEV components such as regulators, inverter, traction machine, and sensors. Simulation results show that the optimum controller gains obtained by intelligent tuning have resulted in satisfactory BEV performance that sustains the harsh environmental conditions. Robustness tests against BEV parameter changes and environmental parameter variations confirmed the effectiveness of intelligent tuning methods.
Today, the Internal Combustion Engine (ICE) is gradually being replaced by electric motors which result in higher efficiency and low emission of greenhouse gases. The electric vehicle either works wholly or partially on electrical energy like battery and ultra-capacitor. The battery or ultra-capacitor is either charged from the AC supply connected to a grid line in a plug-in electric vehicle or from ICE in the hybrid electric vehicle. Alternatively, the battery charges from traction motor by regenerative braking. In the reverse direction, the energy from battery or ultra-capacitor is injected into the AC grid line in the plug-in electric vehicle. Power electronic converters play a vital role in the conversion process from grid line to traction motor and in the reverse direction. In this paper, the role of power electronics converters in an electric vehicle is elaborated. The bidirectional DC-DC converter plays a vital role in the power conversion process of electric vehicles. The existing bidirectional DC-DC converter topologies are discussed with a comprehensive review, comparison and application. Additionally, the advancement in power electronics converters to improve the efficiency and reliability of the vehicular system is elaborated.
Conventional vehicles utilize petroleum-derived fuels for providing good performance and long-range speed. Due to the utilization of petrol or diesel, there are few disadvantages like low fuel economy, exhaust gas emissions which cause environmental pollution. To overcome such problems, this paper addresses the designing of an electric vehicle model, to enhance energy efficiency, reduce emissions, high performance and low maintenance electric vehicles. A simple and low run-time electric vehicle is modelled using simscape components using MATLAB. The dynamic modelled using the drive cycle source, battery, driver controller, power converter, motor, and vehicle subsystem. The power converter is designed using H-bridge with regenerative braking. The vehicle’s kinetic energy is recovered by braking the electric motor in the generator mode. Performance parameters such as vehicle speed, current, State of Charge (SoC), motor RPM and distance are verified with various drive cycles. The distance travelled, speed and torque by the electric vehicle are obtained using the simulation model and results are analysed.
In the present days, the vehicles are primarily
operated for transportation applications. The conventional
energy sources like oil and gas are used as fuel sources of
various vehicles. Since the year 2000, electric vehicles are
commonly used in various countries. Within the previous few
years, the electric vehicle remains a constant topic for the
research community. The drive train can be the main challenge
for the researchers. In this paper, we developed an EV drive train
configuration with the help of AC motors. The developed model
contains a battery source, AC motors (Induction (squirrel cage)
and Synchronous (PMSM), motor controller (DTC (Direct torque
control) and FOC (field Oriented control), PI control, wheels
configuration (Front and Rear) and vehicle body. The model
developed on the Simulink tool of Matlab. A Metaheuristic
optimization algorithm WOA (Whale Optimization Algorithm)
used to optimize the gain parameters of PI control. WOA based
optimized PI controllers can adjust their gains values (Kp and Ki
)
in correspondence to deviations of EV speed and torque and
results in stable speed and torque conditions. The proposed
optimization controllers possess advantages over conventional
controllers in terms of its robustness, to achieve better EV
stability, no speed overshoot and accurate speeds.
Electric Vehicles (EVs) are gaining momentum due to several factors, including the price reduction as well as the climate and environmental awareness. This paper reviews the advances of EVs regarding battery technology trends, charging methods, as well as new research challenges and open opportunities. More specifically, an analysis of the worldwide market situation of EVs and their future prospects is carried out. Given that one of the fundamental aspects in EVs is the battery, the paper presents a thorough review of the battery technologies—from the Lead-acid batteries to the Lithium-ion. Moreover, we review the different standards that are available for EVs charging process, as well as the power control and battery energy management proposals. Finally, we conclude our work by presenting our vision about what is expected in the near future within this field, as well as the research aspects that are still open for both industry and academic communities.
This paper introduces a Fractional Order Field Oriented Control (FO-FOC) with sensorless Model Reference Adaptive System (MRAS) for the Permanent Magnet Synchronous Motor (PMSM). In this work, the conventional integer controllers of the vector control method are replaced with the Fractional Order PI (FOPIα) controllers. Particle Swarm Optimization technique (PSO) is employed to tune the gain, integration parameter and the fractional order parameter for each of the speed, current and MRAS controllers to get the optimum values. The presented methodology is tested using MATLAB Simulink simulation and the results show improved performance of the field oriented control technique by the employment of the fractional order controllers instead of the conventional integer at different operating points. Furthermore, the additional degree of freedom in the fractional controllers helps the PSO technique to get the optimum cost at a very low number of iterations compared with that of the integer one.
Electric and hybrid vehicles are gaining increasing attention in recent years. The distinguished difference between electric/hybrid vehicles from conventional ones is the intermittent on-and-off control of the internal combustion engine, whereas the electric vehicles operate on electrical motors. This difference creates new requirements in lubricants with performance characteristics that are otherwise uncritical: electrical properties (such as electrical conductivity and breakdown voltage) and thermal properties (thermal conductivity, specific heat, among others), in addition to fluidic performance that we have studied for decades. In this review, we discuss about lubricants for electric and hybrid vehicles in the following aspects. Starting with a brief historic review, we gathered information about current needs and challenges in electric and hybrid vehicles. We then compared the properties of lubricants, followed by the performance difference of those vehicles in terms of frictional performance, thermal management, and dielectric breakdown. Performance parameters are critically dependent on the properties of lubricants that are crucial for energy efficiency and reliability. This review can be used as a guidance for the future design of advanced lubricants for electric and hybrid vehicles.
Current studies on the mechanical abuse of lithium-ion batteries usually focus on the mechanical damage process of batteries inside a jelly roll. In contrast, this paper investigates the internal short circuits inside batteries. Experimental results of voltage and temperature responses of lithium-ion batteries showed that battery internal short circuits evolve from a soft internal short circuit to a hard internal short circuit, as battery deformation continues. We utilized an improved coupled electrochemical-electric-thermal model to further analyze the battery thermal responses under different conditions of internal short circuit. Experimental and simulation results indicated that the state of charge of Li-ion batteries is a critical factor in determining the intensities of the soft short-circuit response and hard short-circuit response, especially when the resistance of the internal short circuit decreases to a substantially low level. Simulation results further revealed that the material properties of the short circuit object have a significant impact on the thermal responses and that an appropriate increase in the adhesion strength between the aluminum current collector and the positive electrode can improve battery safety under mechanical abusive conditions.
In recent decades, worldwide global warming and reduction in petroleum resources have accelerated researcher’s attention to produce alternative sustainable and environmentally clean transportation systems. Electrification of vehicular technology is capable of curbing the environmental pollution problem in an efficient and effective way, due to high efficiency electric motors, development and advancement in the field of power electronic devices, digital signal processing and advanced control techniques. This article presents a comprehensive review on different configurations/ architecture of electric vehicles(EVs) and hybrid electric vehicles(HEVs), traction motors for electric propulsion system and high performance speed sensorless control of traction drive. The basic architecture key components of hybrid vehicle and different power train configurations with respect to applications and limitations are discussed. The integral part of electric propulsion system, traction motor classes for desired operational characteristics and limitations are summarized from a system perspective with the latest improvements. High performance traction motor control techniques are discussed with respect to automotive applications. Finally, speed sensorless control techniques research trends as well as an extensive review on rotor speed estimation techniques for robust and efficient sensorless traction drive control are highlighted. This article provides state of the art key global trends and tradeoff of various technologies with future trends and potential areas of research.
The growth of electric vehicles share of total passenger-vehicle sales is evident and is expected to be a very big market segment by 2030. Range of travel and pricing are the most influencing factors that affect their gain in market share. As so, powertrain development is a key technology factor researched by the automotive industry. To explore, among others, how the energy consumption of zero emission vehicles is affected by different transmissions, we developed, built and installed a variety of them on a custom hydrogen fuel cell powered urban vehicle. In this work we present a comparison of the effect, on the energy consumption of the proposed testbed, of a prototype custom build 2-speed gearbox and a single stage transmission. Results presented show a reduction of the overall energy consumption with the use of the 2-speed gearbox, compared to single stage, as well as the effect of gear change speed, related to speed, in energy consumption. Finally, a correlation of experimental results using a custom build CVT is conducted compared to single stage transmission. A comparison to simulation results found in literature is performed for all the transmissions tested on road.
Electric vehicles (EVs) with multi-speed transmission offer improved performances compared to those with single speed transmission system in terms of top speed, fast acceleration, or gradeability along with driving range. In this study, relevant literature is extensively analyzed to explore the performances and associated complexities with multi-speed automatic manual/mechanical transmission (AMT) system in EVs. In EV powertrain, the only torque generator component is electric motor, which is not equally efficient throughout wider speed range. To the other end, vehicles need to run at different speeds in diverse driving conditions. The study shows that multi-speed transmission system enables efficient operation of electric motor by choosing an appropriate gear at different driving torque-speed demands and thus contributes to achieve desired vehicle performances at minimum energy consumption. To demonstrate the differences, both dynamic and economic performances with multi-gear system and single speed system are compared, and the results of various techniques are presented in the form of tables and bar charts. A quantitative analysis is also conducted to show the performance improvement achievable by employing multi-speed transmission concept in EVs. Apart from additional mass, gear ratio selection and torque interruption during gear shifting are major obstacles to improve drivetrain efficiency and riding comfort in EVs with multi-speed transmission system. For optimal gear ratio in transmission system, genetic algorithm (GA) is found to be implemented in most articles. It is also observed that variable shift schedule needs to be considered during the optimization process to get the paramount gear ratios. Tables and bar charts are used to show the results of recent relevant works to these issues. In this article, the readers would gain a comprehensive knowledge on how multi-speed transmission technology can outperform the single speed system within EV platform and what the inherent challenges are.
Pure electric vehicles, as a promising alternative to conventional fossil fuel–powered passenger vehicles, provide outstanding overall energy-utilizing efficiency by omitting the internal combustion engine. However, because of lower energy density in battery energy storage, the driving range per charge is limited by this electrochemical power source, leading to a so-called range phobia and presenting a major barrier for large-scale commercialization. The widely adopted single-reduction gear in pure electric vehicles typically do not achieve the diverse range of functional needs that are present in multi-speed conventional vehicles, most notably acceleration performance and top speed requirements. Consequently, special-designed multi-speed pure electric vehicle–powertrains have been compared and investigated for these applications in this article. Through the optimizing of multiple gear ratios and creating special shifting strategies, a more diverse range of functional needs is realized without increasing the practical size of the electric motor and battery. This article investigates the performance improvements of pure electric vehicle realized through utilization of multi-speed dual-clutch transmissions and continuously variable transmissions. Results reveal that there can be significant benefits attained for pure electric vehicles through multi-speed transmissions. Simulation results shows that continuously variable transmission and two-speed transmission are the two most promising transmissions for pure electric vehicle in different classes, respectively.
With the development of electric vehicle electronic control unit (ECU) for vehicle control technology and the key to raise the level of design electric vehicles the optimization control of the vehicle performance as direction. In order to achieve the rational, coordination of vehicles within the system of integrated control, based on the modular thought, through constructing the distributed control network design overall structure of the control system of pure electric vehicle, the vehicle controller is analyzed on the working principle and its function realization degree, as a pure electric vehicle control system provides the theory basis for performance evaluation.
As electric vehicles become promising alternatives for sustainable and cleaner energy emissions in transportation, the modeling and simulation of electric vehicles has attracted increasing attention from researchers. This paper presents a simulation model of a full electric vehicle on the Matlab-Simulink platform to examine power flow during motoring and regeneration. The drive train components consist of a motor, a battery, a motor controller and a battery controller; modeled according to their mathematical equations. All simulation results are plotted and discussed. The torque and speed conditions during motoring and regeneration were used to determine the energy flow, and performance of the drive. This study forms the foundation for further research and development.
div class="section abstract"> As compared with other batteries, lithium-ion batteries are featured by high power density, long service life, high energy density, environmental friendliness and thus have found wide application in the area of consumer electronics. However, lithium-ion batteries for electric and hybrid electric vehicles (EVs and HEVs) have high capacity and large serial-parallel numbers, which, coupled with such problems as safety, durability, cost and uniformity, imposes limitations on the wide application of lithium-ion batteries in the EVs and HEVs. The narrow area in which lithium-ion batteries operate with safety and reliability necessitates the effective control and through the use of management of battery management system. Battery state of health (SOH) monitoring has become a crucial challenge in EVs and HEVs research, as SOH significantly affects the overall vehicle performance and life cycle. This paper presents both cycling and calendar aging at high and low temperatures. In the proposed model the calendar aging is represented as a function of time, storage temperature and state-of-charge (SOC). On the other hand, cycle aging is represented as a function of energy throughput, cell temperature and C-rate. The cycling and calendar aging models are later combined to formulate an empirical cell-level aging model. The performance of the cell-level empirical aging model is validated by comparing it with the aging test data for different driving scenarios. The aging prediction from the empirical aging model shows very good agreement with the test data with a maximum normalized root mean squared error (RMSE) of 0.85%
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div class="section abstract"> Nowadays electric vehicle is replacing internal combustion engines in the transport sector. The growth of electric vehicles is increasing rapidly to reduce the impact of global warming and climate change. The battery limits the use of electric vehicles as an exact alternative to traditional IC engine vehicles. Specifically, the operating temperature, charge/discharge rates, and internal heat generation of the battery the performance of electric vehicles, like the driving range, charge storage capacity, the cycle life of the battery, and thermal runaway occurring at high temperatures. To overcome these problems, the battery thermal management system (BTMS) controls the temperature of the battery and maintains the optimal temperature to operate the battery efficiently and safely. In the heights of the above facts, the numerical analysis of 18650 Li-ion battery thermal management systems by passive cooling technology using Phase Change Material (PCM). The recent developments in battery thermal management systems, in particular, battery module analysis with and without PCM at different C rates, with and without fin are discussed at length.
Numerical Analysis using ANSYS FLUENT is carried out to determine the effect of the use of PCM on heat transfer in the battery module. Temperature distribution along the battery in the region of PCM with and without the use of fins of various geometries and their configuration are predicted. Among all the geometries studied, the use of “I” section fin had a profound beneficial effect on heat transfer leading to better performance of the battery.
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Developing a high-performance battery thermal management system (BTMS) to keep the temperature of lithium-ion battery (LIB) in a suitable range has become of great interest for electric vehicle (EV) applications. Hence, this study has been set out to design a BTMS by utilizing various combination of phase change material (PCM), metal foam, and fins that keeps the battery surface temperature at the lowest level in normal and harsh environmental conditions under discharging with 3C current rate. Considering these three passive methods, four different cases of BTMS have been designed separately. Moreover, the effects of various fin shapes including rectangular, triangular, trapezoidal, I-shape, and wavy fins are studied for the optimum BTMS. The two-equation local non-equilibrium thermal model has been used which is more precise than the traditional thermal equilibrium model in simulating heat transfer between the PCM and metal foam. The numerical results demonstrated that the optimum BTMS, which is the combination of PCM, metal foam, and fins (fourth case), can reduce the battery surface temperature by 3 K. Furthermore, the maximum delay of about 470 s in melting of the PCM has been reported for this case. Additionally, the applied fins in the fourth case are acting as a network of heat sources to spread heat in the middle of the system, and utilized metal foam can create a uniform distribution of heat between LIB and ambient. Analyzing the effect of different fin shapes on the performance of optimum BTMS showed that there are no remarkable changes between the battery surface temperature of various fin shapes and it would be hard to find a suitable shape of fins for all environmental conditions.
Electric vehicles (EVs) can significantly reduce pollution and dependence on fossil fuels by taking the place of conventional gasoline-powered vehicles. Owing to the higher sensitivity of lithium-ion batteries (LIB) towards working temperatures, thermal management of the battery is necessary for guaranteeing longer-cycle life, higher performance, and the safe operation of EV power systems. Moreover, increasing the rate capability of LIB is highly advantageous to the expediency of EVs application. During the higher charging process, Li-inventory loss, and thermal runaway are pretty obvious. Thus, an effective and advanced battery management system (BTMS) is required to control and dissipate the generated heat from battery cells/pouches/modules. From this perspective, the present review summarizes the latest developments in advanced LIB thermal management for high charge/discharge cycles. Firstly, the severe thermal issue caused by high temperature during fast charging rate and its effect on performance degradation and thermal runway are discussed. The existing advanced BTMS such as cold plate, composite phase change materials (PCMs), hybrid BTMS with PCMs and liquid cooling, and heat pipes are then elaborately presented in the view of fast charging/discharging rate along with the pros and cons. Some new and efficient emerging BTMS, such as refrigerant, thermo-electric and immersion cooling methods for the future BTMS are analyzed. In order to satisfy the thermal requirements, predominantly in dynamic conditions through fast charging rate along with extreme power fluctuations, a combined active and passive cooling mode for BTMS is suggested. This state-of-the-art critical review provides recommendations for the development of advanced BTMS for the batteries under fast charging.
To enhance the lithium-ion battery pack's operating performance while it is continuously used at varying charge rate and higher ambient temperatures, the current research proposes a thermal management system composed of a phase change material with a passive metallic connection. Along with constant charge rate of 1C, 2C and 3C rate, battery pack also investigated at harshest 4C rate condition, to check its thermal performance. In total, three configurations are investigated: configuration 1 has no passive cooling arrangement, configuration 2introduces a passive thermal design with a phase change material submerged cooling technique that includes paraffin wax and extended graphene composite phase change material, and configuration 3is a proposed improved thermal design in which a graphene-enhanced high thermal conductive metallic separator is coupled at the PCM wall to increase PCM temperature delay efficiency. A phenomenon of inefficient thermal performance is observed for typical pure PCM form due to its lower thermal conductivity and heat transfer rate, resulting in a loss of capacity to cause temperature delay effect in battery pack. In proposed improved model of having metallic separator at wall of PCM results shows, none of the case had exceeded effective battery temperature limit of 55°C and liquid fraction rate of PCM and EG CPCM remained below liquidious point which allows it to deliver more temperature delay effect. Comparative performance study between paraffin wax PCM and EG CPCM suggest EG CPCM is able to provide more delay effect due to its thermophysical property advantage of higher thermal conductivity and greater heat transfer performance.
AC pulse heating is a promising preheating method for lithium-ion batteries due to its low energy cost and high efficiency. To avoid the lithium plating in the AC heating, upper bound of heating current (UBHC) should be obtained. In this paper, the dual RC model is developed, and coupled with the thermal model to predict the battery temperature and potential of negative electrode (PNE). PNE=0 V is used as the lithium plating criteria. If the PNE falls to 0 V during the heating process, the lithium plating is triggered, and the corresponding pulse amplitude is the UBHC. Moreover, because the UBHC increases with the battery temperature, the pulse amplitude should be automatically raised to increase the heating efficiency. When the battery temperature is too low, the UBHC is so small that the AC pulse heating is inapplicable. Through the self-adaptive AC pulse based on the UBHC, the heat strategy is built, and the heating time is calculated. The total heating time reached by the proposed strategy increases with the increment of the initial SOC, and it falls with the decrease of the initial battery temperature. Moreover, the heating time has a temperature limit. If the battery temperature is lower than the limit, the battery cannot be heated to the target temperature in the required time. The proposed strategy is applied to heating the battery at the different SOCs, and its performance is compared to the constant amplitude pulse. In the same heating time, the battery temperature achieved by the proposed strategy is at least 7.6 °C higher than the constant amplitude pulse. Moreover, the UBHC is enlarged by 10% to prove the original UBHC can reduce the degradation. The cyclic heating experiment shows that the 110% UBHC reaches a capacity loss of 0.49 Ah after 60 heating cycles and that of the original UBHC is only 0.1 Ah.
The energy transition is an essential effort from a variety of sectors and levels to achieve a carbon-neutral, larger-renewable integrated civilization. The transportation industry, which is largely concentrated in urban areas, emits more than 20% of total greenhouse gas emissions. Various technological difficulties are confronted and resolved as a result of this focus. Consequently, pursuit and research focusing on the integration of electric vehicles (EVs) powered by renewable energy sources are currently a viable option for combating climate change and advancing energy transition. According to current trends, this type of service will diminish the use of internal combustion engines in the future months. A study of the global market scenario for EVs and their future prospects is conducted. Whether energy storage devices and power electronics converters are properly interfaced determines the efficiency of EVs. Moreover, we provide our thoughts on what to expect in the near future in this domain and even the research areas that are still accessible to both industrial and academics.
This study deals with the design of Bernstein polynomials based compensator in order to attenuate the degrading effect of saturation nonlinearities in process control applications. The proposed compensator is structured in terms of Bernstein polynomials and a frequency dependent cost function is utilized in order to calculate the optimal coefficients for the proposed compensator. In order to illustrate the efficiency of proposed compensator, a well-known benchmark process control problem, the coupled tank system, is taken into consideration in this study. The success of the proposed compensator is illustrated via frequency based harmonic plots and time domain plots of saturated control signal.
In order to improve the accuracy of State of Charge / Health (SOC/SOH) estimation, Modified-Sine-cosine Algorithm based dual Extend Kalman filter (MSCA-DEKF) is proposed. Second-order RC model is applied, the model parameters are obtained by Pulse discharge test and Open circuit voltage test (OCV). DEKF is divided into state filter and parameter filter. Nonlinear decrement of transformation parameter r 1 in Sine-cosine Algorithm (SCA) is proposed. Modified SCA (MSCA) is applied to optimizing the covariance noise matrix in the state filter. Parameter filter is applied to estimating the Ohm internal resistance and capacity online, Meanwhile, the time scale of parameters' online update is adjusted to 60 time steps for reducing computing costs. SOH is also obtained by Ohm internal resistance and capacity. Simulation results show that the proposed method improves the accuracy of SOC estimation, and the initial errors of SOC and Ro can be corrected in the first parameter estimation. Ro-based SOH has a better robustness and precision than capacity-based SOH.
In order to achieve accurate state of charge (SOC) estimation of Lithium-Ion Battery, A method that dual Extended Kalman filters (DEKF) optimized by PSO-based Gray Wolf optimizer (MGWO) is proposed. A second-order equivalent circuit model with two resistor-capacitor branches is applied. The battery parameters are determined by battery test. Dual Extended Kalman filters are divided into state filter and parameter filter. Parameter filter is applied to adjust battery parameters online, state filter is applied to SOC estimation. Meanwhile, MGWO is applied to optimize the noise covar-iance matrix to improve the state estimation accuracy of SOC which reduces the linearization error from EKF. The results shows that the accuracy of algorithm is improved by adding online parameter identification and the optimization of the noise covariance matrix, meanwhile, the proposed method can adapt to the initial error well.
Purpose
This paper proposes an improved fatigue life analysis method for optimal design of electric multiple units (EMU) gear, which aims at defects of traditional Miner fatigue cumulative damage theory.
Design/methodology/approach
A fatigue life analysis method by modifying S – N curve and considering material difference is presented, which improves the fatigue life of EMU gear based on shape modification optimization. A corrected method for stress amplitude, average stress and S – N curve is proposed, which considers low stress cycle, material difference and other factors. The fatigue life prediction of EMU gear is carried out by corrected S – N curve and transient dynamic analysis. Moreover, the gear modification technology combined with intelligent optimization method is adopted to investigate the approach of fatigue life analysis and improvement.
Findings
The results show that it is more corresponded to engineering practice by using the improved fatigue life analysis method than the traditional method. The function of stress and modification amount established by response surface method meets the requirement of precision. The fatigue life of EMU gear based on the intelligent algorithm for seeking the optimal modification amount is significantly improved compared with that before the modification.
Originality/value
The traditional fatigue life analysis method does not consider the influence of working condition and material. The life prediction results by using the method proposed in this paper are more accurate and ensure the safety of the people in the EMU. At the same time, the combination of intelligent algorithm and gear modification can improve the fatigue life of gear on the basis of accurate prediction, which is of great significance to the portability of EMU maintenance.
Over the last decade, electric vehicles (EV) have changed the global automobile industry driven by the progress of electronics and powertrain systems. New controllers are manufactured and research has been made not only on motors but on transmissions as well. This paper focuses on describing the types of gearboxes available - continuous variable, automatic, manual - with their pros and cons and the experiments done with different gearsets (plan and gear numbers) single or multigear transmissions on urban or highway cycles to maximise energy efficiency. Gearshift strategies are also a big area of interest alongside simulations testing various gear ratios handled by complex controllers and control algorithms to ensure smooth driving and performance with minimal to low jerk and torque interruption. The aim of this paper is to completely report the work done on transmission software and hardware improvements and also on the top of the shelf technology that the current EVs implement.
To improve the ride comfort of wheel drive electric vehicle, a quarter dynamic model is established for vehicle active and passive suspension. Based on the response root mean square (RMS), the evaluation index of vehicle ride comfort is derived. According to the influence of uncertain parameters on system minimum RMS, the optimal vehicle parameters are determined. To avoid experience value of uncertain weight coefficient affecting the LQG control, analytic hierarchy process (AHP) is adopted to determine the weighting coefficient of vehicle performance evaluation index. And the LQG controller of vehicle active suspension is designed based on optimal control theory. Compared with the analysis results of passive suspension, the effectiveness of active control scheme is verified.
Thermal management of lithium-ion batteries has been a crucial task in the development of battery based electric vehicles. In this paper, the thermal performances of the composite phase change material (CPCM) made of paraffin and high porosity copper foam for the battery modules are presented by means of experiments and numerical simulation. The test battery module consisting of 3 × 5 cylindrical batteries were immersed in the paraffin/copper foam composite enclosed in the aluminum housing. Experiments were conducted for external single-sided liquid cooling and double-sided liquid cooling, in comparison with the natural convection case. The thermal characteristics of the battery module under natural convection conditions were first examined. In order to further reduce the temperature rise, the liquid cooling on the single side and double sides of the battery housing was implemented and tested. It is found that the double-sided liquid cooling has the better temperature control performance with the lowest battery temperature within acceptable temperature difference. Moreover, a two-dimensional numerical model for the battery module with CPCM was also established by taking into account the interfacial gaps. The numerical simulation results were in better agreement with the experimental observations, as against the conventional one-temperature model.
In order to deal with disturbance attenuation problem in the presence of norm bounded uncertainties, different techniques involving ℋ2/ℋ∞ and linear quadratic regulator (LQR) designs exist in literature. The major drawbacks of these approaches may be classified as obtaining controllers with high order terms and too much computational load during the controller design. Hence, two-degree-of freedeom (2-DOF) controller design is taken into consideration in this study in order to avoid some of these drawbacks in the controller design and implementation process for disturbance attenuation problem. Here, the procedure for the design of 2-DOF structure is divided into two parts: designing ℋ∞ controller to stabilize the closed loop system and implementing a higher order sinusoidal input describing functions (HOSIDF)-based compensator as a secondary controller in order to increase the disturbance attenuation performance of the overall closed loop system where the norm bounded uncertainties already exist. Thanks to the Lur’e type system definition that is also used in the design process of HOSIDF compensator, the research also proves that the proposed 2-DOF design structure is suitable to be implemented into the systems involving nonlinearities such as actuator saturation.
This study deals with the design of feedforward compensator for the shake table system via Higher Order Sinusoidal Input Describing Functions (HOSIDFs) in order to reduce the performance degrading effect of the friction existing in the system. In this study, HOSIDFs are used to analyze the effect of Coulomb type friction on the output of the system. The study consists of implementation and design of feedforward compensator whose coefficients are calculated via HOSIDF based cost function given in the study. The study also involves harmonic plots and time-domain result of the system output which is the position of the shake table in order to illustrate the effect of the proposed feedforward compensator which improves the reference tracking performance via the reduction of the friction effect in the shake table system.
Since more and more large battery based energy storage systems get integrated in electrical power grids, it is necessary to harmonize the wording of the battery world and of the power system world, in order to reach a common understanding. In this regard this article presents different battery content values and their relation to each other. Battery operations typically lead to a change of battery’s electric charge or energy content. Based on a simplified battery model the basic values necessary to describe battery operations are clarified. Then the reference values and some acceptance criteria for batteries and secondary cells are defined. Also values describing limited usable energy content caused by operational restrictions are provided. In order to be as close as possible to existing definitions and practical applications, care is taken to be conform to current standards wherever possible in this article. The given set of consistent battery definitions can be used for an agreed design of battery storage systems and provides options for battery performance criteria.
Purpose
Integrated Vehicle Health Management has been developed for several years in different industries, to be able to provide the required inputs to determine the optimal maintenance operations depending on the actual health status of the system. The paper demonstrates the potential of a physics-based model for prognostics with a real case study, based on the detection of incipient faults and estimate the Remaining Useful Life of a planetary transmission of an aircraft system.
Design/methodology/approach
Most of the research, in the area of health assessment algorithms has been focused on data-driven approaches that are not based on the knowledge of the physics of the system; while Physics-based Model approaches rely on the understanding of the system and the degradation mechanisms. A physics-based modeling approach to represent metal-metal contact and fatigue in the gears of the planetary transmission of an aircraft system is applied.
Findings
Both the failure mode caused by metal-metal contact as caused by fatigue in the gears is described. Furthermore the real-time application that retrieves the results from the simulations to assess the health of the system is described. Finally the decision making that can be executed during flight in the aircraft is incorporated.
Originality/value
The paper proposes an innovative prognostics health management system that assesses two important failure modes of the planetary transmission that regulates the speed of the generators of an aircraft. The results from the models have been integrated in an application that emulates a real system in the aircraft and computes the remaining useful life in real-time.
The widespread acceptance of frequency domain techniques for linear and time invariant systems has been an impetus for the extension of these methodologies toward nonlinear systems. However, differences and equivalences between alternative methods have been less addressed. This paper provides a comparative overview of four classes of frequency domain methods for nonlinear systems: Volterra based models, nonlinear frequency response functions / Bode plots, describing functions and linear approximations in the presence of nonlinearities. Each method is introduced using consistent nomenclature and terminology, which allows for comparison in terms of system and signal classes for which the methods are valid as well as the type of (nonlinear) effects captured by each model. Summarizing, the paper aims to connect, and make different frequency domain methods for nonlinear systems accessible, by providing a comparative overview of such methodologies, accompanied by illustrative (experimental) examples.
See https://authors.elsevier.com/a/1UMiQ3PiEzeWm0
Electric and hybrid vehicles are associated with green technologies and a reduction in greenhouse emissions due to their low emissions of greenhouse gases and fuel-economic benefits over gasoline and diesel vehicles. Recent analyses show nevertheless that electric vehicles contribute to the increase in greenhouse emissions through their excessive need for power sources, particularly in countries with limited availability of renewable energy sources, and result in a net contribution and increase in greenhouse emissions across the European continent. The chemical and electronic components of car batteries and their waste management require also a major investment and development of recycling technologies, to limit the dispersion of electric waste materials in the environment. With an increase in fabrication and consumption of battery technologies and multiplied production of electric vehicles worldwide in recent years, a full review of the cradle-to-grave characteristics of the battery units in electric vehicles and hybrid cars is important. The inherent materials and chemicals for production and the resulting effect on waste-management policies across the European Union are therefore reported here for the scope of updating legislations in context with the rapidly growing sales of electric and hybrid vehicles across the continent. This study provides a cradle-to-grave analysis of the emerging technologies in the transport sector, with an assessment of green chemistries as novel green energy sources for the electric vehicle and microelectronics portable energy landscape. Additionally, this work envisions and surveys the future development of biological systems for energy production, in the view of biobatteries. This work is of critical importance to legislative groups in the European Union for evaluating the life-cycle impact of electric and hybrid vehicle batteries on the environment and for establishing new legislations in context with waste handling of electric and hybrid vehicles and sustain new innovations in the field of sustainable portable energy.
Full and free access to article until September 12, 2015 at following link: http://authors.elsevier.com/a/1RQ1z4s9HvhLnn
Electrifying transportation is a promising approach to alleviate the climate change issue. The adoption of electric vehicle into market has introduced significant impacts on various fields, especially the power systems. Various policies have been implemented to foster the electric vehicle deployment and the increasing trend of electric vehicle adoption in the recent years has been satisfying. The continual development of electric vehicle power train, battery and charger technologies have further improved the electric vehicle technologies for wider uptake. Despite the environmental and economical benefits, electric vehicles charging introduce negative impacts on the existing network operation. Appropriate charging management strategies can be implemented to cater for this issue. Furthermore, electric vehicle deployment can bring many potential opportunities to the power grid, especially from the perspective of vehicle-to-grid operation and as the solution for the renewable energy intermittency issue. This paper reviews the latest development in electric vehicle technologies, impacts of electric vehicle roll out and opportunities brought by electric vehicle deployment.
This article deals with a 2-speed inverse automated manual transmission (I-AMT). The design of this transmission permits seamless gear shifting. In order to make the transmission output torque change smoothly during shift process, a control method is put forward. The control method contains a linear feedforward control for motor and clutch during the shift torque phase and a PID control for motor during the inertia phase. The principles of the control system are confirmed through test on an AMESim simulation model of the transmission system. The simulation results indicate that the control algorithm of the transmission system can improve the ride comfort and power performance of pure electric vehicle.
Powertrain of an electric vehicle (EV) is a compound system with an electrical sub-system, such as batteries, inverters, and electrical motors, as well as a mechanical sub-system, including transmissions, differential, and wheels. Since the electrical systems directly affect the vehicle driving performance and dynamics of an EV, integrated modeling considering both the mechanical and electrical systems is essential to assess ultimate kinetic and dynamic characteristics of an EV in terms of input electrical quantities. In this paper, an entire analytic model for the powertrain of EVs is developed to describe EV dynamics with respect to electrical signals, in consideration of both mechanical and electrical systems. Theoretical models based on mathematical expressions, combining the mechanical power system and the electrical power systems, are derived for predicting the final vehicle driving performance as a function of electrical quantities. In addition, a Matlab model of an EV is developed to verify the derived mathematical analysis model. Based on the theoretical model of the powertrain, a variety of relationships between electrical quantities and vehicle dynamics, such as velocity, acceleration, and forces of the EVs, are finally investigated and analyzed.
The paper describes an application of a recently introduced methodology for modeling of a class of nonlinear systems — Higher-Order Sinusoidal Input Describing Function technique (HOSIDF) — to a motion control platform for which a precisely controlled motion at low velocity is required. One of the key challenges for these systems is to compensate for the friction, which is particularly difficult to model at low velocities. The frequency-domain HOSIDF modeling framework is used to assist in designing a feedforward compensator. Experiments with a laboratory benchmark system (gimballed camera platform) prove the technique useful.
Nonlinearities often lead to performance degradation in controlled dynamical systems. This paper provides a new, frequency domain-based method, for detection and optimal compensation of performance degrading nonlinear effects in Lur’e-type systems. It is shown that for such systems a sinusoidal response to a sinusoidal input is necessary and sufficient to show the existence of an equivalent linear and time invariant dynamical model that fully captures the systems’ dynamics for a well-defined set of input signals and initial conditions. This allows to quantify nonlinear effects by using a frequency domain performance measure and yields a novel method to design optimized static compensator structures that minimize performance degrading nonlinear effects. Moverover, the methods discussed in this paper allow to quantify the performance of nonlinear systems on the basis of output measurements only while requiring little knowledge about the nonlinearity and other system dynamics, which yields a useful tool to optimize performance in practice without requiring advanced nonlinear modeling or identification techniques. Finally, the theoretical results are accompanied by examples that illustrate their application in practice.
For high-precision motion systems, modelling and control design specifically oriented at friction effects is instrumental. The sinusoidal input describing function theory represents an approximative mathematical framework for analysing non-linear system behaviour. This theory, however, limits the description of the non-linear system behaviour to a quasi-linear amplitude-dependent relation between sinusoidal excitation and sinusoidal response. In this paper, an extension to higher-order describing functions is realised by introducing the concept of the harmonics generator. The resulting higher-order sinusoidal input describing functions (HOSIDFs) relate the magnitude and phase of the higher harmonics of the periodic response of the system to the magnitude and phase of a sinusoidal excitation. Based on this extension two techniques to measure HOSIDFs are presented. The first technique is FFT based. The second technique is based on IQ (in-phase/quadrature-phase) demodulation. In a simulation, the measurement techniques have been tested by comparing the simulation results to analytically derived results from a known (backlash) non-linearity. In a subsequent practical case study both techniques are used to measure the changes in dynamic behaviour as a function of drive level due to friction in an electric motor. Both methods prove successful for measuring HOSIDFs.
Transient electrochemical model development and validation of a 144 Ah Cell performance under different drive cycles conditions
- R Braga
- A Mevawalla
- S Gudiyella