Field-Circuit Coupled Analysis of an In-Wheel Switched Reluctance Motor with Outer Rotor for EV Applications

Abstract

Abstract. Switched reluctance motor (SRM) is potential to be applied in electric vehicle as an in-wheel drive motor because of its unique feature, such as being allowed to operate in a wide speed range with high efficiency. In this paper, a field-circuit coupled dynamic model is developed with 2D finite element method in Maxwell being proposed to compute the performances of a 10kW/800rpm SRM using the angle position control (APC) strategy. The nonlinear magnetization characteristics have been considered and calculated by FEA. The magnetic fields, windings current, the electromagnetic torque and the terminal characteristics of the prototype SRM are investigated. IntroductionIn-wheel motors for electric vehicle (EV) application is a hot topic among researchers due to environmental concerns [1]. It greatly simplify the mechanical part of the electric vehicle. In last decades, both radial and axial flux permanent magnet (PM) motors are widely used in most of the in-wheel applications [2,3,4]. PM motors offer the highest torque density and therefore will potentially have the lowest weight for given torque and power rating. However, fixed flux magnets limit the speed range of the motor, and there are the dangers of demagnetization phenomenon in permanent magnets. The induction and switched reluctance motors, which have similar torque density, have also been used as in-wheel drive motors [5,6].Comparing with other motors, SRM is potential to apply in EV applications on account of its simple and reliable structure. SRM enjoys flexible control, high efficiency in a wide range of speed, and easy implementation of four-quadrant operation, which is much more important for improvement of electric vehicle performance [7].However, due to the double salient structure of the SRM, the non sinusoidal currents and the magnetic saturation in the motor core during motor operation, the simple and unified mathematical model and analytical equation can not be get easily [8]. The finite element method is a kind of discrete mathematics method which is based on the magnetic field analysis, the SRM model can be precisely built by the method, the SRM performance can be comprehensively and systematically analyzed [9].In this paper, a new field-circuit coupled finite element method by using Maxwell is developed to simulate a 3-phase, 12/8 pole, 10kW/800rpm SRM and its control system. The magnetic fields distribution, the torque, the currents of the SRM with outer rotor are presented.