Axial-Flux Switched Reluctance Motor Design for a Light Electric Vehicle Application

Abstract

The switched reluctance motor (SRM) is an attractive candidate for electric vehicle (EV) propulsion systems due to the lack of rare-earth materials and its robust construction. In this paper, a double-rotor, axial-flux switched reluctance motor is designed for a light electric vehicle (LEV) propulsion application. A target LEV drive cycle is selected for validating the motor sizing. The motor design is realized from a baseline topology and the geometry is adjusted for manufacturability and performance. A novel structural winding is proposed to maximize the axial space available for conductors. A numerical iron loss model is developed that correlates transient finite element analysis (FEA) data to generate representative coefficients for a Bertotti model. The efficiency and torque ripple are simulated using the iron loss model and an electromagnetic torque model. The current control switching angles are optimized for both efficiency and torque quality. It was determined that the vehicle could save 19.6 Wh/km if the torque quality is sacrificed. A lumped-parameter thermal network is constructed to represent the transient thermal behavior of the motor. The transient and continuous torque limits are determined using coupled electromagnetic and thermal models.