Position Sensorless Control in Low-Speed Regions for Non-Saliency and Concentrated Winding Motors

This paper describes a low-speed position sensorless method based on High-frequency signal injection that can be applied to permanent magnet synchronous motors with various characteristics. In the proposed method, a three-phase balanced signals with a frequency of one-third (or one-ninth) of the carrier frequency is injected, and position estimation is performed from the high frequency current generated by the injected high frequency. Furthermore, in order to improve the accuracy of rotor position estimation, the application of synchronous minor sampling processing, which detects current at a sampling period shorter than that of normal current detection, is being considered. The effectiveness of the proposed method is verified through experiments using several commercially available motors that were not specifically designed for sensorless drives.