| Limited fossil fuel resources and environmental concerns are driving industries towards more energy efficient and environment friendly solutions. Players in the automotive industry are producing increasing amount of hybrid electric vehicles and full electric vehicles. Thus, the electric drive system, as an integral part of electric vehicles, is receiving substantial attention from both the industry and academia. Many commercially successful electric vehicles utilize permanent magnet synchronous motor (PMSM) in the electric drive system due to its high torque and power density, and high efficiency. However, in recent years, the uncertainty of the pricing of rare earth materials leads to extensive investigation of rare earth material-free electric machines. Among them, switch reluctance motor (SRM), featuring simple and rugged structure, low cost, and high reliability is a serious contender for electric vehicle applications.;Due to its operation principle, the power of a SRM inherently greatly fluctuates in both motoring and generating modes of operation. This characteristic requires high capacitance in the SRM drive system, which causes increase in volume and decrease in reliability, thus preventing the adaptation of SRMs in electric vehicles, despite their advantages over other competing types of machines. Hence, a thorough investigation and methods of mitigation are important to encourage further adoption of SRMs in the automotive industry.;In this dissertation, operation principle and energy conversion process in SRMs are introduced first to facilitate understanding of the high capacitance requirement in SRM drive systems. A topology that can greatly reduce such requirement is introduced, with its operation principle and control strategy analyzed. Methods to improve the control of the topology and to allow generating mode with SRMs are proposed. Furthermore, a generalized method of reducing capacitance requirement of SRM drive systems is developed. Based on the generalized method, a better topology is then proposed. The operation principle and control strategy of this topology are also discussed. Comprehensive simulations and experiments are conducted to validate the proposed methods, and the results are included in this dissertation. |
