Poles position identification of the permanent magnet motor by the PIPCRM combined with zero voltage vector

The paper shows a sensorless method of rotor position identification of an axial flux permanent magnet motor at very low speed. Presented method is based on stator current measurement in case when zero voltage vector is applied. The method was verified by laboratory tests. The goal of zero voltage vector method is fulfilling gap between method for initial position detecting e.g. PIPCRM (Position Identification by Parallel Current Rate Measurement) and the simple back electromotive force estimation method. The idea of the developed method is to use impact of a back electromotive force on stator current during zero voltage vector. The paper presents results of zero voltage vector method combined together with PIPCRM method applied to start and speed control of the permanent magnet axial flux motor.