Han Bangcheng

Sensorless direct power control for high-speed PMSM based on high-precision rotor position estimation

In order to improve the performance of the high-speed PMSM control system, a sensorless DPC (Direct Power Control) scheme for pump-kind applications is proposed. In the proposed DPC control strategy, a high-precision rotor position estimation is applied to obtain the accurate rotor position angle, which is the key factor for the DPC scheme. An experimental platform has been built, and the experimental results validate effectiveness of the proposed method.

Low rotating loss 2-pole radial magnetic bearing biased with permanent magnet

A new structure of radial magnetic bearing biased with permanent magnet (RPMB), so called 2-pole RPMB is proposed. Based on the original idea, the reduction of flux fluctuation frequency in rotor core to reduce the rotating loss of conventional 4-pole RPMB, 2-pole RPMB has similar structure except the pole-number, which is only half. Based on the measurement of material alternating-loss of rotor core, it is estimated that 2-pole RPMB could reduce rotating loss more than half than 4-pole contrast. To verify the effect on loss reduction, the experiment was carried out based on two magnetically suspended flywheels for energy storage and attitude control on satellite, equipped with 2-pole RPMB prototypes and 4-pole contrast respectively. It has shown that 2-pole RPMB reduced rotating loss by more than 0.85W at the normal speed 30000rpm on both radial and axial supporting statuses, i.e. 14% of flywheel run-down loss with 4-pole RPMB without losses separation. Though the current stiffness of 2-pole RPMB prototype is 23% less, it reduced the total losses because copper loss is small originally due to permanent magnet bias field. Further, during the high speed and large power applications, the loss reduction of 2-pole RPMB would be more meaningful.