Sensorless control of salient pole PMSM using a low-frequency signal injection

This paper deals with sensorless control of permanent magnet synchronous motor. The low-frequency signal injection estimator is studied in the case of salient PMSM. If there is an error in the estimated position, the injected signal creates a torque oscillation and affects the back-emf. The oscillating back-emf can be used to track the position and speed. The saliency of the PMSM is a disturbance for the low frequency estimator. In this paper the effect of saliency is analysed in steady state and a simple method to compensate the saliency effect is proposed. The performance of the method is verified by measurements