Flux weakening control for sensorless IPMSM

Based on the study of interior permanent magnet synchronous motor (IPMSM) sensorless control strategy, the basic principle of PMSM flux weakening control and the reason of technique difficult point of flux weakening are explained. Using a Luenberger observer for speed estimation, flux weakening control method based on motor speed and voltage of q-axis is proposed based on mathematical model of IPMSM. The proposed method uses a torque decoupling technique to regulate the q-axis reference current; d-axis current could be controlled by q-axis voltage in steady state, the error signal of demagnetization current can be obtained by subtracting feedback value from reference value of the q-axis voltage, the demagnetization current can be gained by using PI operation of its error signal. In the stage of motor running in the high speed, the static performance of system is improved while certain extend speed capacity is ensured. The performance of the method is examined using Matlab/Simulink facility, and this method is thoroughly tested by using inverter air-conditioner control system. It is shown in the result that the IPMSM flux weakening control system was of good dynamic and static performances and easily applied.