Position sensorless start-up method of surface permanent magnet synchronous motor using nonlinear rotor position observer

This paper presents a new start-up method from standstill to a sensorless control for surface permanent magnet synchronous motor (SPMSM). To estimate the rotor position of SPMSM from the measured induced voltage, a DC current adds to the motor and nonlinear observer is introduced to the motor torque equation while the motor is vibrating. To achieve the start-up smoothly, first order induced voltage observer also calculates the rotor position during the vibration and the estimation method is replaced after a certain period of time. The validity of the proposed method is verified by experiments using DSP based voltage source inverter.