Simple sensorless algorithm for interior permanent magnet synchronous motors based on high-frequency voltage injection method

This study presents a simple sensorless algorithm based on the high-frequency signal injection for an interior permanent magnet synchronous motor. The sensorless drive using a square-wave-type injection signal has an enhanced control bandwidth and reduced acoustic noise owing to the reduction of filters and availability of high injection frequency. However, this method still needs discrete filters to extract the fundamental and the injected frequency component currents; so it has a limitation in enhancing the sensorless control performance. Therefore this study proposes a simple algorithm, which eliminates these filters and further simplifies the signal process for estimating the rotor position. As a result, the overall sensorless control can be implemented easily without any filters while providing an enhanced dynamics. Additionally, a detection method of an initial rotor position for start-up by using the same square-wave-type voltage injection is introduced. The experimental result shows that the speed control bandwidth in the sensorless drive simplified by the proposed algorithm becomes very close to the one achieved in sensored drives.