S.S. Williamson

Concordia University Montreal, Montréal, Quebec, Canada

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Publications (109)67.07 Total impact

  • Kunwar Aditya, Bernardo Peschiera, Sheldon S. Williamson
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    ABSTRACT: The main objective of this paper is to study and analyze the power supply stage of a series-series (SS) fixed-frequency inductive power transfer (IPT) system, in order to suggest effective soft switching techniques to improve its performance. Because of the characteristics of the system, zero voltage switching (ZVS) operation was used and three control strategies were compared: phase-shift (PS) control, asymmetrical duty cycle (ADC) control and optimal asymmetrical voltage cancellation (o AVC) control. The o AVC control is found to be more efficient for this application. Additionally, this paper presents an inductive power transfer transformer (IPTT) prototype that was built in the laboratory, which helped validate the theoretical analysis and simulation results with practical tests. The plots and circuit simulations were obtained from MATLAB and SIMULINK respectively.
    IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, Dallas, TX, USA; 10/2015
  • Kunwar Aditya, sheldon williamson
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    ABSTRACT: Wireless charging of electric vehicles require a significant air gap between the primary and secondary winding of an inductive power transfer (IPT) system. Due to the existence of the air gap, power flow regulation to keep the output voltage constant becomes a non-trivial task. Hence, the bandwidth, phase margin, and gain margin of the voltage control loops should be appropriately designed, in order to guarantee a robust system. In this paper, a generalized small-signal modelling of series-series compensated (SS topology) IPT system using extended describing function concept has been presented. Using this small-signal model, a controller has been designed for fixed frequency and variable duty cycle, to control the output voltage. Since an asymmetrical clamped mode control (ACM) requires a lower switching frequency compared to the popular fixed frequency control strategies, viz. symmetrical clamed mode control (SCM) and asymmetrical duty cycle control (ADC), it has been used to control the output voltage.
    2015 IEEE Applied Power Electronics Conference and Exposition (APEC), Charlotte, NC, USA; 03/2015
  • Abhijit Choudhury, Pragasen Pillay, Sheldon S. Williamson
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    ABSTRACT: This paper presents an extensive comparative study between a two- and three-level inverter for electric vehicle traction applications. An advanced control strategy for balancing the two dc-link capacitors is also proposed. In this paper, the main focus is on the total voltage harmonic distortion (%THDv), the analytical derivation of the three-level capacitor currents, and the voltage balancing of two capacitor voltages. For generating the gate signals, space vector pulse width modulation (SV-PWM) is used. The developed voltage-balancing scheme helps to reduce the number of converter switching sequences, compared with the conventional SV-PWM strategy, and keeps the voltage difference between the two dc-link capacitors at the desired voltage level. The developed test-bench is used for a permanent magnet synchronous machine drive for electric vehicle (EV) applications. Detailed simulation studies are performed using MATLAB/Simulink block set and experimental verification is achieved using dSpace based real-time simulator. Both the simulation and experimental results show a significant improvement in reduction of total harmonic distortion (%THD (_{textit{v}}) ) for the three-level inverter.
    09/2014; 2(3):529-540. DOI:10.1109/JESTPE.2014.2310140
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    Kunwar Aditya, sheldon williamson
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    ABSTRACT: Recently loosely coupled inductive power transfer (IPT) has gained worldwide attention for battery charging applications for electric vehicles (EVs). Since a high frequency operation is a must for transferring power inductively over a large air gap with reasonable efficiency, a careful design is needed. This paper reviews the basic design considerations for designing such a system. Critical design parameters, such as skin effect, proximity effect (at high frequency), and field-shaping techniques, to reduce leakage flux, has been demonstrated using Finite Element Analysis (FEA). In addition, different compensation technique and control strategies for IPT system has been discussed.
    IEEE Transportation Electrification Conference and Expo (ITEC'14); 06/2014
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    Kunwar Aditya, sheldon williamson
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    ABSTRACT: Loosely coupled inductive power transfer (IPT) systems have recently gained worldwide attention for electric vehicle (EV) battery charging. EV batteries have mainly two charging stages: constant voltage charging and constant current charging stage. Numerous published papers suggest that the secondary of loosely coupled IPT systems, if series compensated, can act as constant-voltage source; and, if parallel compensated, it can act as constant-current source. In this paper the authors have shown that both series as well as parallel compensated secondary can act as constant-current source as well as a constant-voltage source, depending on the nature of power supply. Hence, same topology can be utilized efficiently for EV charging in all the stages. Moreover a detailed comparison of series-series and series- parallel topology has been presented with intention of showing that Series-Series topology represents the best choice for IPT system among the two.
    IEEE Transportation Electrification Conference and Expo (ITEC'14); 06/2014
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    ABSTRACT: Vehicle electrification is a step forward to reduce CO2 emissions. However, using Plug-in Hybrid Electric Vehicles (PHEVs) and Electric Vehicles (EV.) efficiently, battery has to be charged during night to decrease the usage of the Internal Combustion Engine (ICE). There are two methods to charge PHEV battery. Either plugs directly the battery with the electric outlet or using wireless method which uses Inductive Power Transfer (IPT) technology. The aim of this paper is to compare the two methods of PHEV battery charging. The comparison will hold on the energy cost which takes into account the household loads, the solar production, the PHEV driving cycle and the probability that the driver forgets to ping the battery charger. The study will use real data collected at ÉcoTerra house located in Eastman (Québec, Canada).
    IEEE Transportation Electrification Conference, Michigan, USA; 06/2014
  • Kunwar Aditya, Sheldon Williamson
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    ABSTRACT: Loosely coupled inductive power transfer (IPT) systems have recently gained enormous attention for electric vehicle (EV) battery charging. For EV battery charging, a constant-current source is required. Numerous published papers suggest that the secondary of loosely coupled IPT systems, if series compensated, can act as constant-voltage source; and, if parallel compensated, it can act as constant-current source. In this paper, the authors prove that both series as well as parallel compensated secondary can act as constant-current source as well as a constant-voltage source, depending on the nature of power supply. Hence, either of the topological options can be utilized efficiently for EV charging. The authors intend to present the work for the case where primary is in the form of a long track, such as in a mono-rail or electric traction metro system. Hence, the primary is always considered to be series compensated.
    IEEE 23rd International Symposium on Industrial Electronics (ISIE), 2014; 06/2014
  • Siddhartha Anirban Singh, Sheldon S. Williamson
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    ABSTRACT: In recent years, there has been great interest in the research and development of electric vehicles (EVs). In the past 5 years, numerous EVs and plug-in hybrid electric vehicles (PHEVs) have been introduced in the market by auto manufacturers. However, with the increase in demand of EVs/PHEVs comes the need to provide charging facilities at convenient locations, for recharging of the on-board batteries. Fast charging is also a necessity for consumer convenience. Therefore, off-board charging infrastructures have to be looked at closely. This need for fast charging is creating a shift in EV charger development work to focus on DC charging facilities. This paper provides an overview of various power converter topologies used for a photovoltaic (PV) and grid connected DC charging infrastructures. Specific focus is placed on Z-source converters that can be used for a single-stage connection of PV, grid, and EV. PWM control techniques for off-board converters are also reviewed in this paper.
    2014 IEEE Transportation Electrification Conference and Expo (ITEC); 06/2014
  • Abhijit Choudhury, Pragasen Pillay, Sheldon S. Williamson
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    ABSTRACT: This paper presents an advanced switching sequence for space-vector pulsewidth modulation (SV-PWM)-based three level neutral-point clamped inverter. The developed scheme helps to reduce the number of converter switching sequences, compared with the conventional SV-PWM strategy, and keeps the voltage difference between the two dc-link capacitors at the desired voltage level. The developed test bench is utilized for a permanent magnet synchronous machine (PMSM) drive for electric vehicle applications. The proposed strategy is compared with the performance of a PI controller-based voltage balancing strategy. The proposed control strategy is based on the nearest three-vector (N3V) scheme, with a hysteresis control of the dc-link capacitor voltage difference. Conventional N3V scheme uses a higher number of switching sequences, which makes the switching losses higher. In addition, these switching sequences are not same for all subsectors. This makes the switching frequency to vary extensively. In the proposed control strategy, a reduced number of switching sequences are used, and they are same for all subsectors. This makes the system operate with constant switching frequency. Detailed simulation studies are performed to verify the performance of the proposed control strategy. The performance-based test results are then compared with those of a PI controller-based strategy. Experimental test results show significant improvement in the performance of the PMSM with respect to dc-link capacitor voltage variation as well as wide speed and torque range of machine operation.
    06/2014; 2(2):296-307. DOI:10.1109/JESTPE.2013.2296973
  • Abhijit Choudhury, Pragasen Pillay, M. Amar, Sheldon S. Williamson
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    ABSTRACT: A performance comparison study for a two- and three-level inverter based permanent magnet synchronous machine (PMSM) drive has been carried out. A novel space-vector pulse width modulation (SV-PWM) based DC-link voltage balancing algorithm is also presented, to drive the machine from three-level inverter. The proposed algorithm keeps the two DC-link capacitor voltages at their specific voltage tolerance level. Two-level inverter is also feed by space-vector based pulse width modulation (SV-PWM) technique. Total voltage harmonic distortion (THD), capacitor RMS current ripple (Icap), Conduction and switching losses for IGBT and diodes, torque ripple (Trpp) and DC-link capacitor voltage ripple (Vcaprip) are considered to perform the comparison study for both the inverters. Switching losses are calculated in PLECS environment using data sheet parameters from Infineon and control logics are developed in MATLAB/ Sim power system (SPS) tool box. For this study a 110.0 kW surface-PMSM is considered, which are mainly used for electric vehicle propulsion applications. A scaled down prototype is built in laboratory for both the inverters and tested with a 6.0 kW surface-PMSM. Both the simulation and experimental results show satisfactory performance of the proposed system.
    2014 IEEE Transportation Electrification Conference and Expo (ITEC); 06/2014
  • Ebrahim Saeidi Dehaghani, Behzad Asaei, Sheldon S. Williamson
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    ABSTRACT: Battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) are becoming more popular in recent years. Apart from charging vehicles from grid, it has been proposed that electric vehicles (EVs) can help grid with variety of services such as ancillary service, regulation and pick shaving, with reverse power flow. While application of EVs to sustain grid in high demand time will not be a smart idea of the field, helping local distribution grid in the event of power outage in an emergency situation such as floods or storms to improve security and reliability of the grid, may use as a lucrative idea.
    2014 IEEE Transportation Electrification Conference and Expo (ITEC); 06/2014
  • Arash Shafiei, Giampaolo Carli, Sheldon S. Williamson
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    ABSTRACT: Shortage of petroleum is considered as one of the most critical worldwide issues today. At the same time, as of today, car owners worldwide, in general, spend more money at the gas station than they have done ever before. The most practical solution to the transportation industry oil-consumption crisis problems lies in commercially viable electric and plug-in hybrid electric vehicles (EVs and PHEVs). EVs and PHEVs present a significant opportunity to reduce greenhouse gases and dependence on oil. Major automotive companies have already developed exciting new EVs. This chapter presents the structure and basic design aspects of EVs and PHEVs. Future trends in EV manufacturing are also presented. Integration of EVs with green, renewable energy sources is presented, along with an introduction to the design of such systems. Various charging scenarios for EV batteries is presented, when charging at home, at work, or in between routes. Future advanced battery charging infrastructures, such as from combined PV and grid sources are also presented.
    Power Electronics for Renewable Energy Systems, Transportation and Industrial Applications, 05/2014: pages 387-421; , ISBN: 9781118634035
  • Zahra Amjadi, Sheldon S. Williamson
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    ABSTRACT: This paper presents the analysis and novel controller design for a hybrid switched-capacitor (SC) bidirectional DC/DC converter, applicable for electric and plug-in hybrid electric vehicles (HEV/PHEV) energy storage system (ESS) applications, based on power of traction motor and battery current gradient. Features of voltage step-down, voltage step-up, and bi-directional power flow are integrated into a single circuit. The developed novel control strategy enables simpler dynamics compared to a standard buck converter with input filter. Experimental results show, the proposed converter topology enables good regulation capability, low EMI, lower source current ripple, ease of control, and continuous input current waveform in both buck as well as boost modes of operation.
    IEEE Transactions on Smart Grid 01/2014; 5(1):158-166. DOI:10.1109/TSG.2013.2264489 · 4.33 Impact Factor
  • Giampaolo Carli, Sheldon S. Williamson
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    ABSTRACT: It is now clear that the transportation sector will increasingly rely on electricity and the related infrastructure needed for storage and distribution. At the same time, the source of electricity itself must not be carbon based. Rather, whenever possible, it should depend on environmentally responsible processes. In addition to their ecological benefits, aeolic and photovoltaic (PV) sources are highly scalable, and can be utilized for local generation and delivery, eliminating those energy losses normally associated with long-range grid distribution. This paper analyzes one specific type of renewable, local energy generation, applied to electric vehicle charging requirements. A PV source is explicitly posited, because solar panels can be placed above the vehicle parking space, and double as a shade provider. In the first part of this paper, the optimal requirements for overall system are derived. These will be used in the second part, in order to compare alternate power conditioning circuits for this task.
    IEEE Transactions on Power Electronics 12/2013; 28(12):5784-5792. DOI:10.1109/TPEL.2013.2260562 · 5.73 Impact Factor
  • Bernardo Peschiera, Sheldon S. Williamson
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    ABSTRACT: For the last two decades, significant improvements in charging technologies have been made. Moreover, novel applications have been proposed and tested, obtaining important and promising results. Inductive charging for electric vehicles (EV) and hybrid electric vehicles (HEV) is one of them. Because of the positive impact that this technology represents, it is important to understand the general characteristics of this novel application. This paper aims to give a general understanding of inductive charging systems for EV and HEV. The explanation of what is an inductive power transfer (IPT) transformer and how electrical power is transferred through air is presented. The review of the electrical characteristics of an IPT transformer is shown: derivation of equations and presentation of the equivalent circuit. The analysis and comparison of two different circuit topologies is also covered (series-series and parallel-parallel). Also, to validate the theoretical concepts, an IPT transformer setup with 5cm of air gap is simulated. The plots and circuit simulations where obtained in MATLAB and SIMULINK respectively.
    2013 IEEE Transportation Electrification Conference and Expo (ITEC); 06/2013
  • L. Sejpal, L.A.C. Lopes, M. Amar, S.S. Williamson
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    ABSTRACT: This paper concentrates on the application of a three-level Neutral-Point Clamped (NPC) inverter in a Permanent Magnet Synchronous Motor (PMSM) driven electric vehicle. Carrier-Based Space Vector Modulation (CB-SVM) strategy allows a simple technique for inverter switching. A split-capacitor dc bus voltage balancing strategy using a simple PI controller has been presented for the entire speed range of operation of the PMSM. For the same current Total Harmonic Distortion (THD), three-level NPC inverter provides a 65% reduction in switching frequency when compared to a conventional two-level inverter while driving the PMSM with the same parameters. Torque and speed dual loop controllers have been developed using the Field-oriented Control technique to have a wider range of operation beyond the base speed of the PMSM.
    Transportation Electrification Conference and Expo (ITEC), 2013 IEEE; 01/2013
  • Seyoung Kim, S.S. Williamson
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    ABSTRACT: In this paper, a new multiple-input DC/DC integrated converter is proposed for a fuel cell/battery/ultracapacitor electric vehicle. The power density increases in the order of fuel cell, battery, and ultracapacitor and the energy density is reverse of the order. The proposed converter combines interleaved type boost converters and two parallel-connected bidirectional DC/DC converters. The advantages of the proposed converter topology are improved power density, due to the fact that a heavy power transformer is not used, and the state of charge of battery as well as that of the ultracapacitor can be controlled easily.
    Transportation Electrification Conference and Expo (ITEC), 2013 IEEE; 01/2013
  • K.N. Sakib, M.Z. Kabir, S.S. Williamson
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    ABSTRACT: The mathematical modeling of the voltage dependent current-voltage (I-V) characteristics of Cadmium Telluride (CdS/CdTe) Solar cell and utilizing that modeling mathematics in to circuit or industrial level application has been analyzed in this paper. A single cell is developed based on the mathematical model and a solar module/network is constructed considering a series and parallel combinations of the single cell. The I-V characteristics of the cell is used as a source. The module performance is analyzed under various operating conditions. To extract the power from the solar cell, Perturb and Observe (P&O) Maximum power point technique has been used. A general resistive load is used in the circuit presented in the paper. Then instead of simple resistive load, a battery including the charge controller to discharge any load is used in the analysis.
    Industrial Technology (ICIT), 2013 IEEE International Conference on; 01/2013
  • A. Choudhury, P. Pillay, S.S. Williamson
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    ABSTRACT: This paper presents a modified DC bus voltage balancing algorithm for a neutral-point clamped (NPC) three-level inverter based motor drives for permanent magnet synchronous machines (PMSM) used in electric vehicle applications. The topology used for DC bus voltage balancing is based on nearest three vectors (N3V) with a space vector pulse width modulation scheme (SV-PWM). In this scheme, the voltage space vectors are rearranged based on the four redundant small voltage vectors, to keep the two DC link capacitor voltages in their specific tolerance bands, even during fast transient conditions of the machine. This topology provides high stability and lower switching loss compared to the conventional N3V scheme. The performance of the proposed scheme is verified by simulation and hardware experimental tests.
    Industrial Electronics Society, IECON 2013 - 39th Annual Conference of the IEEE; 01/2013
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    ABSTRACT: Plug-in Hybrid Electric Vehicles (PHEVs) are seen to be a step forward in vehicle electrification, to replace ICE based conventional vehicles. Using a PHEV implies that part of the vehicle energy comes from the grid or other sources, such as renewable energy, to charge the battery. However, renewable energy sources being intermittent sources, these new needs would only shift the problem by increasing the number of nuclear and coal power plants, and will not permit solving the problem of pollution or fossil fuel depletion. There is a need to optimize the way, in which the available resources are utilized, in order to reduce dependency on nuclear and coal power plants. This will achieve the overall goal of minimizing pollution, reducing the depletion rate of fossil fuels, as well as reduce the overall cost. This paper proposes a hybrid power system for house energy needs by utilization of renewable energy sources, grid, as well as the PHEV battery source. Emphasis of paper is on optimization of the overall cost of the system, by selecting the most cost effective and feasible option among the available options; namely, renewable energy sources, the grid and the battery of the PHEV. As a prerequisite to the implementation of this scheme, it is desirable to work out an approximate amount of available energy. For this, the efficiencies of the various power converters involved must be determined and taken into account to reduce the energy losses.
    Transportation Electrification Conference and Expo (ITEC), 2013 IEEE; 01/2013