Symmetrical signaling system for sensor-less SRM drive

SRMs, switched reluctance motors, are being expected as an excellent candidate for power sources in harsh environments due to the simple structure. In spite of many methods proposed to eliminate the rotor position sensor, which is needed to commutate the current correctly but not compatible with harsh environments, no successful sensor-less method has been seen so far. The method proposed in this paper enables one to eliminate the sensor by introducing a signal onto windings of a phase in a common mode manner and detecting the induced voltages on the other phases. The method has proved to be practical through simulations and experiments on a test setup. The SRM on the test setup rotated at revolving speed of 100,000 min^-1 and more with the system.