A Sensorless Starting Control Strategy for Switched Reluctance Motor Drives with Current Threshold

A new sensorless starting scheme for a three-phase switched reluctance motor is proposed in this article. To implement this scheme, the following was done. First, at standstill, the phase inductance subregion logic is developed for estimating the initial exciting phase. Next, at low-speed operation, by injecting high-frequency pulses in the non-excited phases, the current slope differences are estimated and compared for estimating commutation signals. Finally, in order to avoid the large negative torque generated by the freewheeling current, a modified sensorless control logic is developed by using a preset current threshold. The experimental results are presented and compared for verification. The results show that this scheme can start the switched reluctance motor without hesitation, and it is quite easy for implementation without adding any additional hardware and complex calculation.