Research On Sensorless Control Of Permanent Magnet Synchronous Motor At Zero Low Speed Range

With the continuous optimization and adjustment of global energy structure,China has begun to focus on clean energy.As an efficient clean energy,electric energy is expected to gradually replace the dominant position of traditional fossil energy in the society in the future.According to statistics,most of the power consumption is completed by motor.Permanent magnet synchronous motor(PMSM)has gradually replaced the traditional induction motor because of its high mechanical efficiency,high power density,fast dynamic response and strong load capacity.PMSM has been widely used in the field of industrial control,especially in the field of high-precision servo CNC machine tools,robots,UAVs and so on.In the high-precision servo control system of PMSM,in order to ensure the smooth start of the motor and avoid the disadvantages of large volume,poor anti-interference ability,high cost and low reliability caused by the use of photoelectric encoder or resolver,a sensorless control strategy based on PMSM is proposed,which has been highly concerned by many experts and scholars.Aiming at the hot research direction of sensorless control of PMSM,the sensorless control of PMSM at zero and low speed is studied by using high frequency voltage injection method.The main contents of this paper are as follows:(1)The development history of the motor is introduced in this paper,including the birth,development process and future trend of PMSM.At the same time,the working principle and control mode of PMSM are discussed.The paper focuses on the analysis of sensorless control of PMSM,and uses high frequency voltage injection method to estimate the rationality of rotor position and speed under zero low speed condition.The method is explained as the research direction of this paper.(2)According to the structure of PMSM,the mathematical models of PMSM in natural coordinate system,static coordinate system and rotating coordinate system are derived.In addition,three coordinate systems are often used in PMSM when using vector speed control strategy,and the transformation between the three coordinate systems is analyzed.Finally,the initial position angle detection methods of PMSM at zero speed are summarized.(3)The rotating high frequency voltage injection method is used to detect the initial position angle of PMSM at rest.Firstly,the principle of rotating high frequency voltage injection method is introduced,the rotor position detection process is deduced,and the rotor position detection accuracy is improved by using the least square curve fitting method instead of the traditional approximate linear estimation method.Finally,on the basis of detecting the position angle of the motor,the magnetic pole is judged to further ensure the reliability of detecting the position angle.(4)The rotor position and speed of PMSM at low speed are identified by pulse high frequency voltage injection method.Through the design of a reasonable position observer,the MATLAB / Simulink simulation shows that the position observer can effectively identify the PMSM rotor position and speed information when the motor is running at low speed,and has good robustness and dynamic response ability.(5)The hardware system and software system of the experimental platform are introduced.The sensorless control algorithm of PMSM is built in the experimental platform,and the sensorless control algorithm of PMSM is verified in the range of zero and low speed.(6)This paper summarizes the research on sensorless control of PMSM,and puts forward some shortcomings in the research of this subject.Finally,it describes the work that needs to be further improved in the future.