Development of line-start PMSM with solid rotor for electric vehicles

A solid rotor permanent magnet synchronous motor (PMSM) is developed for the electric propulsion part in electric vehicles (EV). The rotor in this kind of motor is composed of splits solid rotors, interior permanent magnets and starting bars. Thus, it's a very complex electromechanical process for solid rotor PMSM pulling into synchronization and it is difficult to analyze and calculate the starting and operating performance under different load exactly, which would be very important for EV application. In this paper, a 30kW solid rotor PMSM with simply structure was taken as the analysis model, and the numerical calculation model under assumptions, as well as the solving regions of the derived model, is proposed. Then the 2D transient electromagnetic fields of this motor were calculated by using an improved finite element method. Starting performance and operation performance were analyzed, and some parameters as stator current, power factor and torque-speed characteristic could be obtained. From the study on performance of machine with different load, influence of operating load on motor performances was studied. The calculated results show good agreement with the experimental data. Some reasonable conclusions were obtained, which can provide some help for the design of this kind of PMSM and the application of it in EV.