Kaushik Rajashekara

Power Electronics and Motor Drives in Electric, Hybrid Electric, and Plug-In Hybrid Electric Vehicles

With the requirements for reducing emissions and improving fuel economy, automotive companies are developing electric, hybrid electric, and plug-in hybrid electric vehicles. Power electronics is an enabling technology for the development of these environmentally friendlier vehicles and implementing the advanced electrical architectures to meet the demands for increased electric loads. In this paper, a brief review of the current trends and future vehicle strategies and the function of power electronic subsystems are described. The requirements of power electronic components and electric motor drives for the successful development of these vehicles are also presented.

Topological overview of hybrid electric and fuel cell vehicular power system architectures and configurations

This paper discusses the operational characteristics of the topologies for hybrid electric vehicles (HEV), fuel cell vehicles (FCV), and more electric vehicles (MEV). A brief description of series hybrid, parallel hybrid, and fuel cell-based propulsion systems are presented. The paper also presents fuel cell propulsion applications, more specific to light-duty passenger cars as well as heavy-duty buses. Finally, some of the major fundamental issues that currently face these advanced vehicular technologies including the challenges for market penetration are highlighted.

A High Power Density Single-Phase PWM Rectifier With Active Ripple Energy Storage

It is well known that there exist second-order harmonic current and corresponding ripple voltage on dc bus for single phase PWM rectifiers. The low frequency harmonic current is normally filtered using a bulk capacitor in the bus which results in low power density. This paper proposed an active ripple energy storage method that can effectively reduce the energy storage capacitance. The feed-forward control method and design considerations are provided. Simulation and 15kW experimental results are provided for verification purposes.

Hybrid fuel cell strategies for clean power generation

A hybrid system consists of a combination of two or more power generation technologies to make best use of their operating characteristics and to obtain efficiencies higher than that could be obtained from a single power source. Since fuel cells directly convert fuel and an oxidant into electricity through an electrochemical process, they produce very low emissions and have higher operating efficiencies. Hence combining fuel cells with other sources, the efficiency of the combined system can be further increased. In this paper, different types of fuel cell hybrid systems and their applications are presented. They are classified based on the need for improving the efficiency or extending the duration of the available power to the load as a back-up power.

Comprehensive Efficiency Modeling of Electric Traction Motor Drives for Hybrid Electric Vehicle Propulsion Applications

Extensive research done in the recent past has proven that power electronic converters and electric propulsion motors are extremely critical components for modern hybrid electric vehicle (HEV) propulsion applications. Therefore, it is essential that both the traction motor and the associated drive operate at their optimal efficiencies throughout the driving schedule. In typical HEV propulsion applications, the traction motor and the drive are used over the entire torque/speed operational range. In view of this fact, this paper aims at modeling the inverter and motor losses/efficiencies over typical city and highway driving schedules. The noteworthy losses within a typical three-phase dc/ac traction inverter, such as the switching and conduction losses for both the insulated-gate bipolar transistors and the antiparallel diodes, are modeled and simulated over the city and highway driving patterns. An induction motor (IM) is used for a medium-sized sport utility vehicle, which was modeled in the advanced vehicle simulator (ADVISOR) software. The significant IM losses that were considered in the study include the stator copper losses, rotor copper losses, and core losses. Thus, the average efficiencies of both the inverter drive and the induction traction motor are evaluated and summarized under city as well as highway driving conditions. Finally, based on the individual-model-based efficiency analysis, the overall traction motor drive system efficiency is estimated.

Present Status and Future Trends in Electric Vehicle Propulsion Technologies

In this paper, the current status and the requirements of primary electric propulsion components-the battery, the electric motors, and the power electronics system-are reviewed. The future trends in the electric propulsion systems, battery charging, and the types of power trains are presented. Possible future electric vehicle powertrain systems based on lithium air battery and plug-in fuel cell vehicles are also discussed.

Power conversion and control strategies for fuel cell vehicles

With the requirements for reducing the emissions and improving the fuel economy, the automotive companies are developing fuel cell systems for propulsion and for on-board power generation. Power electronics is an enabling technology for the development of environmental friendly fuel cell vehicles, and to implement the various vehicle electrical architectures to obtain the best performance. In this paper, power conversion strategies for propulsion and auxiliary power unit applications are described. The requirements of the propulsion system, power electronics, and control for the successful development of the fuel cell vehicles are also presented.

History of electric vehicles in General Motors

The propulsion systems being used by General Motors in different electric vehicle projects are described, and the performances achieved are presented. The past projects discussed are electrovan, an electric truck for military application, STIR-LEC I (a Stirling electric hybrid car), the GM512 series car. The AT&T van, and the Electrovette. Current projects such as IMPACT and the electric shuttle bus are also discussed. The IMPACT was developed because of a concern for air quality. The technology of impact is based on advanced propulsion system technology and is suitable for mass production at affordable costs. >

A 1200-V, 60-A SiC MOSFET Multichip Phase-Leg Module for High-Temperature, High-Frequency Applications

In this paper, a high-temperature, high-frequency, wire-bond-based multichip phase-leg module was designed, fabricated, and fully tested. Using paralleled Silicon Carbide (SiC) MOSFETs, the module was rated at 1200 V and 60 A, and was designed for a 25-kW three-phase inverter operating at a switching frequency of 70 kHz, and in a harsh environment up to 200 °C, for aircraft applications. To this end, the temperature-dependent characteristics of the SiC MOSFET were first evaluated. The results demonstrated the superiority of the SiC MOSFET in both static and switching performances compared to Si devices, but meanwhile did reveal the design tradeoff in terms of the devices gate oxide stability. Various high-temperature packaging materials were then extensively surveyed and carefully selected for the module to sustain the harsh environment. The electrical layout of the module was also optimized using a modeling and simulation approach, in order to minimize the device parasitic ringing during high-speed switching. Finally, the static and switching performances of the fabricated module were tested, and the 200 °C continuous operation of the SiC MOSFETs was verified.

A High-Temperature SiC Three-Phase AC - DC Converter Design for > 100/spl deg/C Ambient Temperature

High-temperature (HT) converters have gained importance in industrial applications where the converters operate in a harsh environment, such as in hybrid electrical vehicles, aviation, and deep-earth petroleum exploration. These environments require the converter to have not only HT semiconductor devices (made of SiC or GaN), but also reliable HT packaging, HT gate drives, and HT control electronics. This paper describes a detailed design process for an HT SiC three-phase PWM rectifier that can operate at ambient temperatures above 100°C. SiC HT planar structure packaging is designed for the main semiconductor devices, and an edge-triggered HT gate drive is also proposed to drive the designed power module. The system is designed to make use of available HT components, including the passive components, silicon-on-insulator chips, and auxiliary components. Finally, a 1.4 kW lab prototype is tested in a harsh environment for verification.