Initial position estimation for sensorless surface-mounted PMSM with near-zero saliency at standstill

An initial rotor position estimation method for surface-mounted permanent magnet synchronous motor (PMSM) without any position sensor at standstill is presented. Oscillating high-frequency signal is injected to estimate the magnet pole position. The error signal containing with rotor position information is acquired from the q-axis current component in the estimated synchronous reference frame. In order to make rotor polarity be identified more effectively and simply, pulse voltage vectors is injected in the corresponding direction. The validity of the proposed estimation scheme is verified by an 11.7 kW surface-mounted PMSM with near-zero saliency. Experimental results show that the proposed scheme achieve acceptable estimation accuracy.