An Investigation of Servo Motor Structure for Sensorless Control Based on High-Frequency Injection Method

This paper presents the motor structure suitable for sensorless drives based on high-frequency injection method. The position estimation accuracy is related to the saliency ratio of the motor.Although the motor with increasing saliency ratio under the load condition have been reported, however the mechanism of the phenomenon has not been explained.The improvement of the saliency ratio in the conventional structure is explained in terms of magnetic flux distribution. Moreover, the increase of the saliency ratio by further structural improvement is examined, and the effect is confirmed by experiments.