Sensorless Control Of A Permanent Magnet Synchronous Motor Based On High Frequency Injection Method

Permanent magnet synchronous motor(PMSM)has gotten more and more extensive application in the area of servo control,electro mobiles,aeronautics and astronautics,robot control and other advanced technique fields in recent years for its excellent performance of various kinds.Since there are many problems in mechanical position sensors which is used in PMSM control system,it is of great significance to study the sensorless techniques of PMSM.This thesis focuses on sensorless control of PMSM based on the high frequency injection method,mainly including the following parts:1.Firstly,this thesis introduced the background of the research and the development of PMSM's control strategy.And then the current state of the commonly used position-estimation algorithms were reviewed and the high frequency injection method was selected as the research priority by comparison.2.Since the high frequency injection method is based on vector control system,PMSM models in different coordinate systems were derived in detail and the principle of vector control system was explained at length based on the PMSM model of rotating coordinate system.Then several commonly used control strategies in PMSM vector control system were introduced in brief.At last,the high frequency signal PMSM model was extended.3.The high frequency voltage signal injection method can be classified into the rotational voltage signal injection method and the pulse voltage signal injection,and both of the two methods were deduced separately based on the high frequency signal PMSM model.Then the two methods were simulated under Matlab/Simulink environment and the results were compared.By combining the theory and the simulation results of the two methods,a conclusion was drawn that both the high frequency rotational voltage injection method and the pulse injection method can estimate the motor rotor position effectively in real time,but the former is more stable,easy to adjust the system parameters and has smaller dynamic response fluctuation,the latter possesses higher stable state estimation precision and lower torque ripple,thus each of the two methods have its own advantages.4.In order to solve the problem of feedback unit delay in digital PLL which influences the performance of high frequency injection methods,a novel digital PLL was proposed to compensate the feedback unit delay,and the following simulation and experiment proved its effectiveness.Then the novel digital PLL was applied to high frequency rotational voltage injection method and it was verified through simulation that the novel digital PLL enhances the stability and dynamic performance under disturbance condition of the system.5.The author built the hardware and software platform and conducted the experiment of the high frequency rotational voltage injection method,the high frequency pulse voltage injection method and the rotational voltage injection method using novel digital PLL.The experiment results verify the correctness of the conclusion drawn in this thesis.