The sensorless rotor position identification and low speed operation of the axial flux permanent magnet motor controlled by the novel PIPCRM method

This paper presents a novel simple sensorless method, which can be used at standstill and at low speed of the permanent magnet machine. The method is used to determine initial position of the rotor of the permanent magnet axial flux motor. Therefore method is applied to provide sensorless startup of axial flux permanent magnet motor. Low speed operations, including changing direction is developed and described. A single voltage step is applied to stator windings connected parallel and current responses, in each phase, are measured. Identification of rotor position is provided due to current response differences and it analysis. Described sensorless method is called as PIPCRM that means Position Identification by Parallel Current Rate Measurement. This paper deals with theory of the PIPCRM method confirmed by laboratory results on experimental set with 40 kVA / 16 poles / 3000 rpm axial flux permanent magnet motor. The torque and speed control of the shaftless and bearingless permanent magnet motor is presented using the developed sensorless method.