Sensorless Starting Method for High-Speed Brushless DC Motor Based on Quasi-Current Source Inverter

During the sensorless starting process of highspeed brushless DC motors (HS-BLDCM), the small stator resistance and inductance will cause large starting current, and the speed estimation error will cause incorrect switching of self-synchronous operation. Focused on these problems, a constant current frequency up acceleration starting method based on quasi-current source inverter (QCSI) is proposed in this paper. First, a QCSI is applied to directly control the current amplitude of the constant current inductance, and the motor can be accelerated with constant torque by keeping the constant inductance current of QCSI. Then, the commutation instants are calculated based on this uniform acceleration process, and the number of acceleration steps is designed to achieve self-synchronous operation switching, which avoids incorrect switching caused by speed estimation error during the starting process. Finally, the experimental results verify the effectiveness of the proposed method.