PM motor sensorless position detection based on iron B-H local hysteresis

A sensorless position detection technique for a permanent magnet (PM) motor with non-salient rotor is presented. It is shown that the phase self inductances and resistances measured at higher frequencies vary slightly with the rotor position. The origin of the variations is found in the iron B-H hysteresis characteristics. In order to exploit these small variations for the rotor position detection, a measurement setup is proposed. The technique is tested and shows good results and promises further developments.