Improved mutual voltage technique of indirect rotor position sensing in switched reluctance motor

This paper describes a new method of indirect rotor position sensing for switched reluctance motors (SRMs). The method performs well in the pulse width modulated (PWM) region and is applicable to both hard chopping and soft chopping. The proposed method suitably samples two mutually induced voltages on an inactive phase, and the difference of these two voltages is used to compute the ratio of mutual inductance to self-inductance. Then, this signal can be used to estimate easily the shaft position. Simulated results validate the theoretical analysis and demonstrate the successful sensorless position sensing of the SRM.