Sensorless DTC 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. For super high-speed PMSM system, the speed sensor is costly and easy to be damaged, and it is difficult to be built in the super high-speed PMSM, which also reduces the strength of the motor. The sensorless DTC is proposed to control the super high-speed PMSM, because the stator flux linkage can be controlled directly in direct torque control (DTC) system of PMSM, the field-weakening control becomes easier; and DTC does not need accurate rotor position information. Two kinds of speed estimator are presented, one is based on the angle of the stator flux linkage; the other is based on the angle of the stator flux linkage. Based on the data of the super high-speed PMSM (105 Kw, 61000 rpm) designed for the national "863" plan, a lot of simulation experiments are done. The results show that both methods can well and truly estimate the speed of the PMSM when the PMSM steadily runs. Because the torque angle variety is considered, the speed estimator that is based the rotor flux linkage vector angle can make the motor start steadily and have good precision. It is proved by the simulation experiments that it is feasible to be used in sensorless DTC system of super high-speed PMSM, and it is simple and easy to implement.