A Novel Position-Sensorless Startup Method for DSEM

The self-inductance of doubly salient electromagnetic motor (DSEM) varies with the rotor position; it is an effective approach to rotor position in the DSEM driving system. With knowing the initial rotor position by the conventional method, this paper proposes a novel sensorless startup method, which is based on the feature that there must be a change in the magnitude relation of two proper phase self-inductances when the rotor goes from one sector to the other. Accurate and quick estimation of rotor sector is achieved with only one test injection pulse required, and the injected test pulse will not produce negative torque unless the rotor passes the commutation instants. Compared to the conventional sensorless startup strategies, the proposed method owns advantages in commutation accuracy and output torque. The experiments on a 12/8-pole DSEM validate the correctness and feasibility of the proposed method.