Simple rotor position estimation using the current saturation at a standstill

This paper proposes a simple initial rotor position estimation method to improve the starting performance of sensorless control using back-EMF. The proposed method uses relative magnitudes of the current at a standstill which are in inverse proportion to the variation of the inductance of the stator winding due to saliency of the rotor. This method is easy to be implemented and can help to successfully startup without start failures or reverse rotating and makes the estimation procedure quicker and easier than other conventional method using saturation of the current by the inductance, and doesn´t require any other external devices and is not affected by motor parameters. The validity of the proposed initial rotor position estimation method is demonstrated by experiment.