A low-cost sensorless drive for slim motors with analog filter and shift circuit free

This paper shows two sensorless commutation methods for the slim axial-flux permanent magnet brushless motor. The proposed sensorless drive methods solve the crucial problem of the sensorless slim motor drives; there are no zero crossing points of terminal voltage because there is a high armature current response. Hence, suitable sensorless techniques are developed based on the line-to-line voltage and the characteristic of a high response current, so it requires no low pass filters or phase-shift circuits, and is suitable for high speed or low cost applications.