Rotor position sensing in switched reluctance motor drives by measuring mutually induced voltages

A novel method of indirect rotor position sensing (IRPS) for switched reluctance motor (SRM) drives is described. The principle is based on the mutually induced voltages in phases adjacent to the energized phase of an SRM. The mutually induced voltage (MIV) in the off phase varies significantly as the rotor, corresponding to the energized stator, moves from its unaligned position towards complete alignment. This MIC variation is captured by a simple electronic circuit and then processed in a microcontroller to determine the commutation instants, thereby eliminating the need for direct rotor position sensors in an SRM. Successful operation of a four-phase SRM drive has been demonstrated in the laboratory using this mutual voltage technique of IRPS. The theoretical aspects of MIVs in an SRM and the relevant experimental results are presented