Date of Award

11-6-2015

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Electrical and Computer Engineering

First Advisor

Kar, Narayan

Keywords

Switched reluctance motor

Rights

CC BY-NC-ND 4.0

Abstract

The recent interest by the automotive industry in finding an electric motor that has high power density, rugged construction with high temperature adaptability, and fault tolerance ability has revived the research on switched reluctance motors (SRMs). Due to the aforementioned characteristics, SRM is considered an attractive alternative to traditional electric motors in electric vehicle (EV) applications. However, there are challenges such as torque ripple and acoustic noise that need to be addressed. The aim of this dissertation is to provide solutions through fundamental design improvements in order to develop a viable SRM-based propulsion system. In order to analyze and quantify the major well-known issues of SRM, firstly, a case study based on finite element analysis (FEA) is performed on two types of SRM designs, a conventional SRM and a new design of in-wheel outer-rotor SRM. Despite the improvement in torque ripple provided by the new design, a comparative performance analysis suggests that further design modification is necessary in order to mitigate the acoustic noise and vibration issue in the machine while maintaining the achieved improvements. Consequently, an axial-flux configuration of SRM is proposed and its design and analysis is presented. Detailed procedure of deriving the output power equation as a function of motor dimensions and parameters are provided. A novel modified phase winding design method is thoroughly explained, and the inductance determination by different methods is verified experimentally. A 3-D FEA unveils excessive end core and radial flux fringing effects, subsequently, an exclusive pole-shape design is proposed. The dynamic operation of the motor is analyzed through 3-D FEA motion model. The prototype development process and static testing are demonstrated. Experimental investigations have revealed issue of low inductance ratio due to higher leakage flux in this type of machine. Subsequently, three different novel approaches based on segmented grain-oriented steel core and magnetic shielding are proposed to mitigate the leakage flux, and then tested individually using 3-D FEA. In addition, comparative performance analysis of the original machine model and the machine with each of these approaches is carried out and improvement in the inductance ratio is observed. Overall, the proposed ASRM, with all aforementioned design improvements is found to satisfactorily address the major challenges.

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