ROTOR POSITION SENSING IN SWITCHED RELUCTANCE MOTOR-DRIVES BY MEASURING MUTUALLY INDUCED VOLTAGES

This paper describes a new method of indirect rotor position sensing f or switched reluctance motor (SRM) drives. The principle is based on m easuring the mutually induced voltage in an inactive phase which is ei ther adjacent or opposite to the energized phase of an SRM. The mutual voltage in the ''off'' phase, induced due to the current in the activ e phase, varies significantly as the rotor, corresponding to the energ ized stator, moves from its unaligned position towards complete alignm ent. This mutually induced voltage variation is captured by a simple e lectronic circuit and then processed in a microcontroller to determine the commutation instants, thereby eliminating the need for direct rot or position sensors in an SRM. Successful operation of a four-phase SR M drive has been demonstrated in the laboratory using the mutual volta ge (MV) technique of indirect rotor position sensing. The theoretical aspects of mutually induced voltages in an SRM and the relevant experi mental results are presented in this paper.