A novel strategy of initial rotor position detection for surface mounted permanent magnet synchronous machines

This paper proposes a novel strategy of initial rotor position detection in sensorless control for surface mounted permanent magnet synchronous machines (SPMSM). Firstly a high frequency pulsating signal is injected into the estimated synchronous rotating coordinate, thus the primary estimated rotor position can be obtained through closed-loop adjustment. Then deriving the rotary carrier-frequency component signals from the three-phase carrier SPWM inverter. Utilizing heterodyne method to deal with the carrier-frequency component signals, the rotor pole judgment signal can be achieved. Combining the primary estimated rotor position with the rotor pole judgment signal, the accurate initial rotor position can be detected. The simulation results verified the correctness of the theoretical analysis.