Estimation of Rotor Position for Permanent Magnet Synchronous Motor at Standstill Using Sensorless Voltage Control Scheme

The zero-speed rotor position estimation in surface mounted permanent magnet synchronous motor (SM-PMSM) represents a challenge due to the weak magnetic saliency in this type of motors. This article presents a new method to estimate the initial rotor position of SMPMSMs more simply and more accurately without any form of position or current sensors. It achieves this goal through an injection of three short width pulses and employing only the measurements of the motor terminal voltage responses, which fluctuate sinusoidally with the rotor position. Thereby, memory addresses, or dimensions of a lookup table, were created from the readings of the measured voltages. The memory was primarily loaded with 360 angles, each represents 1° angle of rotor positions. The simulated MATLAB model and experimental results demonstrate the advantages. Comparing with the previous related publications, this research work has fulfilled two main contributions. The first is in achieving a rotor position estimation of 1o resolution. The second is in eliminating the technique needed for detection of the rotor magnet polarity. The measured rates of error for the MATLAB model and the practical model were 2% and 5%, respectively.