An improved back-EMF based initial rotor position estimation for IPMSM

This paper proposes a simple initial rotor position estimation method to improve the starting performance for back EMF-based sensorless control. The proposed estimation is achieved at standstill by using the relative magnitudes of the current which is in inverse proportion to the variation of the inductance of stator winding due to saliency of the rotor. This initial rotor position estimation method is easy to be implemented with back EMF-based sensorless control 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 affrected by motor parameters. The validity of the proposed initial rotor position estimation is demonstrated by experiment.