PERMANENT MAGNET SYNCHRONOUS MOTOR DRIVES FOR ELECTRIC VEHICLES

Abstract

Permanent magnet synchronous motor (PMSM) drives have been successfully developed to fulfil the special requirements for electric vehicles such as high power density, high starting torque and high cruising speed. The present thesis is based on three main topics; a design of permanent magnet synchronous motor, design verifications with finite element method and simulation of drives and control with constant torque and flux-weakening region. Permanent magnet synchronous motor is designed for electric vehicles (EVs). The rotor configuration considered in this study is the inset/interior permanent magnet (1PM-spoke) type. An analytical software (SPEED) is used to design geometrical dimension of machine and to simulate the machine and drives static and dynamic behaviour. To verify design and get finer results, finite element method (FEM) software ANSYS is used for electromagnetic analysis. The designed PMSM model is transferred to finite element analysis (PEA) program. This work also deals with the coupling of the two software tool - SPEED and ANSYS. The coupling of simulation tools allows to simulate the behaviour of more complex geometries like that of a conventional electric machine. The simulation parameters depending on the geometry of the machine can be adjusted. The modelled machine's parameters, obtained from the analytical method and FEM, are compared and verified by experimental results. To enable drive for electric vehicle application, a new current regulation control algorithm proposed that provides drives to operate in constant torque and flux-weakening region with optimum current. The control adjusts q- and d-axis current command based on commanded torque considering speed and do link voltage. Time domain simulation of the behaviour of the drive including inverter with control algorithm is carried out in t ' 1 Matlab/Simulink. The designed paramet rf the machine from analytical and FEM tool has been used in the time domain simulation. Simulation results are presented for the drives operating in low speed high torque, high speed and change in speed/torque conditions to demonstrate the drive performance with proposed control algorithm.