Research On Hybrid Rotor Position Identification Method For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM) has small size, simple structure,light weight, small loss, high efficiency, reliable operation, flexible motor size andshape, and many other advantages. And it is easily controlled and maintained.Compared with induction motor, the rotor structure is greatly simplified, and thestability of motor running is improved. Because of its high precision, high dynamicperformance and wide range of position and speed control, vector control system ofPMSM has been widely used in industry, agriculture, defense and other fields.In this paper, vector control system of surface mounted PMSM is built based onrotor flux oriented and id=0control method. These simple control algorithms can notonly achieve stator current and rotor flux decoupling control, but also implementthe maximum ratio of torque to current. In order to overcome the defects which isbrought by the installation of speed sensor, influencing high-frequency signalinjection method is used to estimate the rotor position. The method which does notdepend on the motor fundamental equations and parameters is based on natural orartificial motor salient effect. Rotor position and speed including zero speed can beeffectively estimated. However, this method requires to inject harmonic signalcontinuously, and lead lag estimation of rotor position and speed that caused by theuse of multiple filters, especially cann’t track dynamic processes at high-speed. Andthe low-speed performance of sliding mode observer is relatively poor. In order tocomplement each other, a hybrid rotor position identification control system isestablished in this paper. High-frequency signal injection method is used to ensuremeasurement accuracy of rotor position and speed at zero-speed and low-speed, whilesliding mode observer is used to ensure fast dynamic response at high-speed. In orderto solve the high-frequency jitter problem which caused by discontinuous Bang-bangcontrol of the sliding mode observer, the continuous saturation function is introducedinstead of the discontinuous switching function.Finally, simulation models of the sensorless control system are built based oninfluencing high-frequency signal injection method and hybrid sensorless controlmethod respectively. And the advantages and disadvantages of both methods arecompared. Simulation and experimental results show that the hybrid rotor positionidentification method which has low harmonic, robust, small torque ripple and good dynamic performance can be applied at full speed range including zero-speed. Andboth ways of the hybrid method can be switched smoothly.