A new sensorless control for switched reluctance motor

Abstract

This paper describes a new rotor position sensorless control method for switched reluctance motor (SRM) drives based on the variation of an active phase inductance. The phase inductance regularly varies with the rotor position and increases as the rotor and stator poles are approaching alignment. When the rotor and stator poles are aligned, the phase inductance has a maximum value, and thereafter the phase inductance decreases. In the low speed region, the SRM can be controlled without the position sensor by changing the excitation when the slope of the phase inductance becomes zero or less than zero. As the speed increases, this method cannot be applied because of the large negative torque produced by the regenerative current. Therefore, the SRM must be controlled so that the current can be zero at the aligned position approximately. To implement smoothly this operation, the sensorless control method using the difference between the phase inductance at the aligned position and the phase inductance calculated every sampling is introduced. In the high speed region, a new technique with the difference of both phase inductances is successfully used. Experimental results present the validity of the proposed method