Narayan C. Kar

A Survey and Comparison of Characteristics of Motor Drives Used in Electric Vehicles

In recent times, the worldwide price of fuel is showing an upward surge. One of the major factors leading to this can be attributed to the exponential increase in demand. In a country like Canada, where a majority of the people own vehicles, and more being added to the roads, this demand for fuel is surely going to increase in the future and will also be severely damaging to the environment as transportation sector alone is responsible for a larger share of pollutants emitted into the atmosphere. Electric vehicles offer one way to reduce the level of emissions. Electric motor drives are an integral component of an electric vehicle and consist of one or more electric motors. In this paper an effort has been made to compare different characteristics of motor drives used in electric vehicles and also given is a comprehensive list of references papers published in the field of electric vehicles

A Comparative Study of Power Supply Architectures in Wireless EV Charging Systems

This paper examines two of the primary power supply architectures being predominantly used for wireless electric vehicle (EV) charging, namely the series LC (SLC) resonant and the hybrid series-parallel (LCL) resonant full-bridge inverter topologies. The study of both of these topologies is presented in the context of designing a 3-kW primary-side controlled stationary wireless EV charger with nominal operating parameters of 30-kHz center frequency, a range of coupling in the neighborhood of 0.18-0.26, and a parallel secondary pick-up with partial series coil compensation. A comparison of both architectures is made in terms of their design methodology, physical size, cost, complexity, and efficiency. It is found that the SLC architecture is 2.45% less costly than the LCL topology. On the other hand, it is observed that the LCL architecture achieves almost 10% higher peak efficiency at rated load and minimum coupling. The study also showed that the SLC topology suffers from poor light load efficiency, while the LCL topology maintains very high efficiency over its full range of coupling and loading. The study also revealed that the capacitor voltage stress is significantly higher in the SLC topology. Finally, it is also shown that the control complexity of the SLC architecture is higher than that of the LCL architecture because of its sensitivity to changes in the reflected secondary impedance, which result in loss of constant current source and ZVS operation unless a suitable combination of parameters are modulated by the closed-loop controller.

Designing and Prototyping a Novel Five-Phase Pancake-Shaped Axial-Flux SRM for Electric Vehicle Application Through Dynamic FEA Incorporating Flux-Tube Modeling

Switched reluctance motors (SRMs) show crucial attributes to applications where light weight, high-temperature adaptability, fault-tolerance capability, ruggedness, and simplicity are strongly required. The axial-flux configuration of SRM has additional features over the radial-flux configuration. This paper presents the design and analysis of a novel axial-flux SRM. Detailed procedures of deriving the output power equation as a function of the motor dimensions and parameters are provided. A modified phase winding design approach is thoroughly explained, a flowchart describing the design algorithm is presented, and the inductance determination by different methods is verified experimentally. The 3-D finite-element analysis (FEA) unveils the excessive end core and radial-flux fringing effects in the axial-flux configuration. An exclusive pole-shape design is also proposed. The operation of the motion model using 3-D dynamic FEA is analyzed, and its prototype development process and static testing are demonstrated.

Design and Implementation of Neuro-Fuzzy Vector Control for Wind-Driven Doubly-Fed Induction Generator

Wound-rotor induction generators have numerous advantages in wind power generation over other types of generators. One scheme is realized when a converter cascade is used between the slip-ring terminals and the utility grid to control the rotor power. This configuration is called the doubly-fed induction generator (DFIG). In this paper, a vector control scheme is developed to control the rotor side voltage source converter that allows independent control of the generated active and reactive power as well as the rotor speed to track the maximum wind power point. A neuro-fuzzy gain tuner is proposed to control the DFIG. The input for each neuro-fuzzy system is the error value of generator speed, active or reactive power. The choice of only one input to the system simplifies the design. Experimental investigations have also been conducted on a laboratory DFIG to verify the calculated results.

Battery pack modeling for the analysis of battery management system of a hybrid electric vehicle

Battery forms a critical part of the hybrid electric vehicle (HEV) drivetrain. An important constraint to the effective performance and reliability of the battery is its unpredictable internal resistance variation along the driving cycle. Temperature has a considerable effect on this internal resistance and thus the battery management system monitors cell and battery pack temperature in accordance with the state-of-charge to prevent thermal runaway. Li-ion batteries which offer possible solutions to the HEVs energy and power density demands thus need to have a good thermal management system in order to enhance their performance. This paper aims to develop a battery pack model that would analyze the variation of internal resistance as a function of temperature. The study of the losses would help in designing a cost effective efficient battery management system.

A Twofold Daubechies-Wavelet-Based Module for Fault Detection and Voltage Regulation in SEIGs for Distributed Wind Power Generation

As Canada and the world move rapidly toward increased reliance on wind power generation, self-excited induction generators (SEIGs) will play an important role in distributed wind power generation (DWPG). Understanding the significance and prospects of SEIGs in DWPG, first, this paper elucidates the significance of fault detection (FD) and voltage regulation (VR) in the aforementioned application. A comprehensive analysis of VR and faults on niche industrial 7.5-hp copper-rotor SEIG and conventional 7.5-hp aluminum-rotor SEIG is performed through numerical simulations, and the calculated results are validated through experimental investigations. Second, a twofold Daubechies-wavelet-transform-based module is designed for the following: 1) FD and 2) VR, respectively. A discrete-wavelet-transform-based algorithm is proposed and implemented on a low-cost embedded system to provide an economical solution for the aforementioned issues. Thereafter, the aforementioned schemes are tested, and results are investigated.

A novel five-phase pancake shaped switched reluctance motor for hybrid electric vehicles

Switched reluctance motors (SRMs) have been gaining increasing popularity and emerging as an attractive alternative to traditional electrical motors in hybrid vehicle applications due to their numerous advantages. However, large torque ripple and acoustic noise are its major disadvantages. This paper presents a novel five-phase 15/12 SRM which features higher power density, very low level of vibration with flexibility in controlling the torque ripple profile. This design is classified as an axial field SRM and hence it needs three-dimensional finite-element analysis model. However, an alternative two-dimensional model is presented and some design features and result are discussed in this paper.

A novel PI gain scheduler for a vector controlled doubly-fed wind driven induction generator

Wound-rotor induction generator has numerous advantages in wind power generation over other generators. One scheme for wound-rotor induction generator is realized when a converter cascade is used between the slip-ring terminals and the utility grid to control the rotor power. This configuration is called the doubly-fed induction generator (DFIG). A vector control scheme is developed to control the rotor side voltage-source converter. This scheme allows the independent control of the generated active and reactive power as well as the rotor speed to track the maximum wind power point. Conventionally, the controller type used in vector controllers is of the PI type with a fixed proportional and integral gain. In this paper, a simple yet efficient way by which the controller can change its behavior is proposed. In the proposed controller, different characteristics representing the variation in the proportional and the integral gains as a function of the absolute value of the discrepancy between the set speed (for max. power generation) and the actual rotor speed, i.e. the error, is used. These characteristics are expressed by linear, exponential, piece wise linear, second- and fourth-order functions. The transient speed responses using the aforementioned characteristics are compared with the ones determined by using the conventional PI controller with fixed gains. By using the proposed controller, it can be seen that more accurate control and quicker transient response is achieved for different operating conditions

Investigation of Permanent-Magnet Motor Drives Incorporating Damper Bars for Electrified Vehicles

Understanding the need for steady-state and transient performance improvement in an interior permanent-magnet synchronous machine (IPMSM) drive, this paper exclusively investigates the IPMSM incorporating damper bars in the rotor of electric motor for electrified vehicles (EVs). First, motivation for the employment of damper bars in IPMSM is provided and justified with a case study. Thereafter, a mathematical model of an IPMSM drive with damper bars in the rotor has been developed based on dq-axis theory and validated through experiments performed on a laboratory IPMSM containing damper bars. The validated mathematical model has been then employed to arrive at satisfactory rotor bar parameters for an existing IPMSM on board a commercially available EV. Moreover, a replica of the existing onboard EV motor with and without incorporating dampers have been designed, and finite-element analysis has been performed to investigate various performance characteristics. Comparative performance analyzes of both the machines with and without damper bars under steady-state and transient conditions have been performed wherever necessary, and the results elicited have been discussed.

Design of a Novel Wavelet Based Transient Detection Unit for In-Vehicle Fault Determination and Hybrid Energy Storage Utilization

This paper addresses the performance and reliability issues as encountered by the present EV technology. The research work presented in this paper is based on an ongoing project which has a twofold research motivation: 1) use of wavelet analysis to determine transients in electric vehicles; and 2) application the information obtained during transient detection to address the performance and reliability concerns. The novel wavelet based transient detection unit designed and developed as part of this project is discussed in this paper. The prototype is developed on a low-cost embedded system in order to provide an economical solution. Significance of the developed transient detection unit is also illustrated in this paper by developing applications that ensure a robust and reliable drivetrain with enhanced performance. Firstly, the information gathered from the transient detection unit is used to determine in-vehicle electrical faults. Secondly, this transient detector is used to facilitate the optimization of hybrid energy storage system (battery/ultra-capacitor combination) and to ensure smooth battery operation.