Sensorless control of surface permanent magnet synchronous motor using a structured adaptive flux observer

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