MTPA based DTC for Permanent Magnet assisted Synchronous Reluctance Motor for Electric Vehicle application

A new maximum torque per ampere (MTPA) based direct torque control (DTC) method is proposed in this paper for a permanent magnet assisted synchronous reluctance motor (PMaSyRM). The central idea of the proposed control algorithm is to dynamically adjust the value of stator flux reference in accordance with the load torque. The envisaged idea enables reap more benefits from the motor drive mainly under low or no-load conditions. Analytical expression for the stator flux reference needed is presented. In addition, this paper also presents a methodology to determine the core loss component of the PMaSyRM that enables estimation of electrical losses in the motor. Firstly, performance characteristics obtainable from the PMaSyRM using the proposed MTPA based DTC is presented under different conditions. Secondly, they are compared with that obtainable from the conventional DTC method to showcase the superiority of the MTPA based DTC proposed in this paper. This is further examined by considering the Indian Drive Cycle (IDC) and an electric vehicle (EV) model. Results in terms of reduced core losses, stator copper losses and improved motor efficiency etc. are presented in support of the fusion of MTPA with DTC methods for PMaSyRM.