Study on direct torque control of super high-speed PMSM

Due to the features such as high efficiency, small volume and high power density, super high-speed permanent magnet synchronous motors (PMSM) are becoming attractive recently. Generally, V/f control method is adopted, for it flexible and easy to be realized. However, because the reasons of the stator reactance littler and the effects of the dead- time on the output voltages and currents of the PWM inverter more severe than common PMSM, the V/f control system of the super highspeed PMSM has poor stability ability and bad dynamic performance. In the paper, the DTC system of the super highspeed PMSM is presented, and its simulation model is founded. Based on the data of the super high-speed PMSM (105Kw, 61000 rpm) designed for the national "863" plan, a lot of simulating experiments were done for open-looped V/f control and DTC method, the results well demonstrate that the open-looped V/f control system has the problem of stability, and the DTC system of the super high-speed PMSM owns better dynamic performance, stronger robustness and anti-disturbance ability. In addition, because the torque of the super high-speed PMSM has fast dynamic response ability and the DTC is easy to realize, the scheme presented in this paper is feasible in such PMSM applications as high-speed micro-turbine generators, centrifugal compressors and pumps.