Position Sensorless Control Method for Doubly Salient Electromagnetic Machine Based on Non-Conduct Phase Current Injection

The conventional position sensorless control for the doubly salient electromagnetic machine (DSEM) introduces the extra voltage sensor, which reduces the reliability of the motor drive system. Hence, a position sensorless control method based on non-conduct phase current injection is proposed in this paper. In the proposed method, the constant duty cycle voltage pulse is injected into the non-conduct phase and the response current amplitude is compared to the pre-set commutation threshold to determine the current commutation point. To solve the inherent delay of current sampling, an online compensation strategy by adjusting the commutation threshold is proposed. The position sensorless control method in this paper only needs current sensors to perform commutation without the requirement of voltage sensors.