Sensorless position identification of permanent magnet motor by zero voltage vector

The paper presents a simple sensorless method, which can be used to determine poles position of a permanent magnet axial flux motor. Described method is related to impact of a back electromotive force on current shape produced when a zero voltage vector is applied. A goal of this method is poles position detection for speed range from 2% of nominal speed of the motor. The goal of zero voltage vector method is fulfilling gap between method for initial position detecting e.g. PIPCRM and simple back electromotive force estimation method. Presented method has been tested on experimental set using 40 kVA / 16 poles / 3000 rpm axial flux permanent magnet motor.