Study On Permanent Magnet Synchronous Motor And Drive System In Electric Vehicle Application

There is abundant rare-earth storage in China. To China, it is an advantage to develop Electric vehicle (EV) with Permanent Magnet Synchronous Motor (PMSM) as the tractor. This paper studied on PMSM and its drive system in EV application. Sum up, this paper mainly includes: Aiming at improving the utilization rate of materials and power density of motor, the first section developed a 18.5kW PMSM cooled with water in EV application, by optimum designing the structure of the rotor. Based on the mechanical analysis of the EV in operation, it obtained the rating parameters and performance data of prototype PMSM. On the analysis of the rotor magnetic field of Surface Mounted PMSM (SMPMSM), this paper put forward an optimized rotor structure. With special design of the structure between rotor poles, the prototype PMSM reduced the magnetism leakage between poles, lowered the magnetism leakage coefficient, and increased the utilizing degree of rotor permanent magnet. The second section developed a direct torque control (DTC) drive system for EV based on DSP TMS320LF2407A. In this section, the structure of the drive system, and a scheme of communication protocol through CAN bus between the drive system and other modules in EV were presented.The last section studied on some questions involved in the DTC strategy of PMSM in EV application. They included the effect of zero voltage vector in PMSM DTC, the select principle of space voltage vector, the control of stator magnet chain, the enhance of system dynamic performance, and the realization of PMSM DTC system. This paper provided the software structure of DTC system. To improve the system performance at low speed, some measures were adopted, and the precision of stator flux estimator was increased. The experimental result of the DTC system at low speed was presented.