Research On Sensorless Control Of Permanent Magnet Synchronous Motor Based On Combined Singal Injection

Rotor position information is the key to controlling the magnetic field orientation of permanent magnet synchronous motors.The quality of position feedback will directly affect the control performance of the motor system.In the high dynamic electromechanical actuation systems of high-end equipment such as aerospace,the actual working conditions of the servo system has the characteristics of frequent start and stop,rapid response,and large load changes,requiring high requirements for position estimation.However,the existing sensorless control methods are difficult to meet the requirements of high-performance servo control in terms of convergence speed,estimation accuracy,and anti-interference,and cannot be directly applied to the control loop of high dynamic electromechanical actuation system.In order to improve the dynamic characteristics of sensorless control of permanent magnet synchronous motors at zero low speed,this thesis proposes a high dynamic sensorless control method based on the combination of high-frequency square wave voltage signal and square wave current signal injection.By injecting a high-frequency square wave voltage signal into the estimated d-axis and demodulating the high-frequency response current of the q-axis,high dynamic rotor position estimation is achieved.Simultaneously estimating the given square wave current signal on the daxis,the motor quickly enters magnetic saturation.Determine the polarity of the estimated rotor position by comparing the amplitude of the positive and negative current ripple on the d-axis.The main research contents are as follows:Firstly,selecting three-phase PMSM as the research object,elaborating on the definition of coordinate axis system and its transformation relationship,and summarizing the principle of PMSM vector control;Based on this,the basic principle of sensorless control at zero low speed was analyzed,and an analytical model of the motor under high-frequency excitation was derived.Secondly,he mechanism of sensorless control based on sinusoidal pulse injection and square wave injection was elucidated,and two simulation models of sensorless control systems based on pulse injection were constructed;The dynamic and steady-state performance of two control methods were compared and analyzed,and a technical approach to achieve high dynamic sensorless control using high-frequency square wave signal injection was proposed.Thirdly,analyzed the polarity identification problem introduced by high-frequency pulse injection,studied the basic principle of rotor magnetic polarity identification,and proposed a high dynamic rotor position detection method based on combined square wave injection,including rotor position observer design and magnetic polarity identification method injected with square wave current signal,providing a theoretical basis for experimental verification.Fourthly,we have built a permanent magnet servo motor system experimental platform,completed the hardware circuit design and debugging of the control system,as well as software programming of the algorithm.The experimental results of the sensorless control method for permanent magnet synchronous motors based on combined square wave injection proposed in this thesis were verified on the established experimental platform.The experimental results show that the proposed method in this thesis only has a total time of10 ms for position estimation and polarity identification under zero and low speed operation of the motor,with a position estimation error of 3°.Compared to existing methods,the convergence speed of position estimation is significantly improved while ensuring estimation accuracy.The use of window integration further enhances stability and robustness.When the motor is rapidly adjusted and the load changes,the proposed method can still meet the control requirements of high dynamic servo systems in terms of tracking characteristics,estimation errors,and other indicators.