Sensorless control for electrically energized synchronous motor based on signal injection to field winding

A sensorless algorithm was developed for electrically energized synchronous motor(ESM). It is different from the techniques for PMSM to inject a carrier signal to the rotor winding. The relation between the angle estimation error and the rectified high frequency signal was derived straightforwardly with cross coupling inductances. And we develop compensation method for cross-coupling effect, and imply several advantages of proposed method in comparison with signal injection to stator winding. This method is much robust against magnetic saturation because it is not depend on saliency of rotor. Furthermore, proposed method does not need to check polarity at standstill. The experiments and simulation were performed to demonstrate improvement of compensation of cross coupling, robustness against magnetic saturation, and full load operation. We obtained accurate estimated position angle.