Sensorless control of surface permanent magnet synchronous motor using a new method

In this paper, a new approach to sensorless speed control and initial rotor position estimation for a surface permanent magnet synchronous motor (SPMSM) drive is presented. At a rotating condition, the speed and rotor position estimation of the SPMSM drive is obtained through a self adaptive flux observer (SAO) by only measuring phase voltages and currents. The initial rotor position is estimated by using the nonlinear magnetization characteristics of the stator core, which is caused by the rotor magnets. Experimental results show that in both steady and transient states, the system can achieve all the expected performances.