Sensorless control of PMSM based on state observer in the steady and transient state operations without phase lag

This paper proposes a suite of sensorless control method based on the state observer for the permanent magnet synchronous motor (PMSM) running either in the steady state or in the transient state. The state observer is firstly designed for the PMSM running in the steady state. Then the paper proposes a transient algorithm based on state observer suitable for the motor in the transient state without phase lag. Besides, the load torque observer is designed when the load torque of the motor is unknown. Finally, simulation results are presented, and verify the effectiveness of the paper's design.