Modular Multistage Permanent Magnet Synchronous Motor Drive System Simulation Based On EV

Energy saving and environmental protection affect industry trends constantly nowadays, the development of electrical vehicle(EV) is an inevitable choice in the future of transportation industry. Although EV is applauded in the market, the limited charging mileage has become the main reason to restrict its popularity. The operation of EV has characteristics like frequently starts and stops, large range of speed and load. The electric drive system requires high efficiency in overall operating range. Ordinary electric drive systems achieve high efficiency in the range of medium speed and medium torque, thus efficiency decreases significantly in low speed-high torque and high-speed operating area.Permanent magnet synchronous motor(PMSM) is becoming the research focus of EV drive system because of small size, high power density, high efficiency and low noise advantages. In order to improve overall efficiency and operation range of EV drive system, this paper puts forward modular multistage PMSM supplied by dual inverters, the system chooses winding connection which is with optimal efficiency in different speed and torque operating area. Drive system efficiency in overall operating area is calculated in Ansoft and Matlab platform under diverse winding connections. Distribution of high efficiency areas is analyzed and the optimal efficiency switching boundary is integrated. The double disc PMSM winding switching vector control model based on optimal efficiency switching boundary is builded in Simulink, driven by dual inverters. Whole vehicle dynamic model is builded based on the electric drive model, in order to evaluate dynamic performance and driving efficiency.Simulation results show that, applying winding switching significantly increases the range of high efficiency area. During winding switching, speed and torque response rapidly, speed curve is smooth, the impact on driving is negligible. Car condition simulation results confirm that within winding switching, EV mileage obviously improves, the energy consumption per unit distance reduces greatly.In the light of torque ripple problem when modules connect in parallel, this paper presents PWM phase-shifting method on inverters. Simulation shows that within PWM phase-shifting, the torque errors of two modules offset each other, total torque ripple reduces and operation stability improves. This method has reference value on other parallel inverters application.This paper aims at improving EV drive system overall efficiency based on winding switching. The analysis method and conclusion has guiding significance.