A novel impedance model based sensorless operation of PMSM

There are two problems to be solved in application of high frequency (HF) signal injection method in sensorless, low speed or position servo systems. One problem is that full torque startup needs precise estimation of static rotor position. Another is that the speed regulation range is confined since the estimation error grows while the rotor speed grows because of the phase lag comes from synchronous rotating filter. The effect on the accuracy of static rotor position estimation based on HF impedance model is analyzed in this paper and a novel impedance model instead of inductance model is utilized in static position estimation method to improve the static estimation precision. A simple phase compensation method is utilized to enhance the dynamic performance of the sensorless control system. Simulation results indicate that the established sensorless control system has both improved static and dynamic estimation accuracy. Meanwhile, the system has a strong tolerance of load disturbance which is vital for applications in low speed servo systems.