New modulation encoding techniques for indirect rotor position sensing in switched reluctance motors

Rotor position information is essential in switched reluctance machines (SRMs) in order to generate the phase excitation pulses for optimum control of the motor. In this paper, two new methods of indirect rotor position sensing are presented. These methods are based on the modulation techniques which are commonly used in communication systems. The instantaneous phase inductance of a nonconducting phase is extracted in an encoded form using a modulator consisting of electronic circuitry. The signal is then decoded to obtain the instantaneous inductance from which the shaft position is determined. An analysis of these modulation techniques along with the implementation scheme using a microcontroller is presented in this paper