A position sensorless drive using estimation of turn-off angle under regenerative braking in switched reluctance motor

This paper describes a position sensorless control technique for switched reluctance motors (SRMs) based on variation of the phase inductance. The sensorless drive is carried out by determining the turn-off timing under regenerative braldng mode. The commutation is carried out so that the phase current becomes zero at the position where the stator and rotor poles start to separate. To determine the commutation timing, the variation of the phase inductance and the de-fluxing period are used. At low speeds, the voltage pulse is applied to the phase that should be neat excited and the inductance computed in this phase is used to turn off the excitation. Experimental results show that the SRM can be well controlled without the position sensor.