Sensorless control of the axial flux permanent magnet synchronous motor at standstill and at low speed

The paper presents a simple sensorless method, which can be used at standstill. Therefore method can be used to determine initial poles position of the axial flux permanent magnet motor. Moreover presented method can yield rotor position at low speed. An appropriate speed range for the method is limited. The paper shows the way of extend that speed range. Identification of rotor position is provided by current responses which are result of the single test voltage step. This paper deals with theory of the method confirmed by laboratory results on experimental set with 40 kVA / 16 poles / 3000 rpm axial flux permanent magnet motor.