Research And Implementation Of Sensorless Control For Permanent Magnet Synchronous Motor

With the improvement of social productivity,the concept of low cost,high efficiency and energy saving is gradually accepted by people.Permanent magnet synchronous motor(PMSM)is widely used in civil,industrial and other fields because of its advantages of high power factor and high power density and so on.PMSM with position sensor control is widely used in robot and computer numerical control machine tools with high precision requirements.In the water pump,fan,aerator and other occasions only requiring speed control,PMSM is gradually replacing AC asynchronous induction motor(ACIM)by virtue of its advantages,but the addition of sensors will undoubtedly increase the control cost and even reduce the system stability.Therefore,the sensorless control technology of PMSM has broad application prospects,and it has become a research hotspot of experts and scholars at home and abroad.In this paper,a sensorless control method based on sliding mode observer(SMO)is studied for PMSM,which includes rotor initial position detection,I/F starting,d-q axis inductance calculation by motor line inductance,and continuous sigmoid function is used to replace the original saturation function as the switching function.This method has the advantages of smooth starting,accurate current observation model and improving the robustness of SMO control.The main contents of this paper are as follows:(1)Collect and read a large number of domestic and foreign literatures on sensorless control methods of PMSM,and elaborate different control methods and their characteristics at low speed and medium high speed.(2)According to the saturation effect of PMSM magnetic circuit,the detection method of rotor initial position and I/F starting are analyzed,and the relationship between line inductance and d-q axis inductance parameters is deduced based on the mathematical model of PMSM.(3)According to the mathematical model of PMSM,the current observation equation of sliding mode observer is established,and the forward difference and improved Euler method are used to discretize it.The sigmoid function is studied as the switching function,and the rotor position observation phase-locked loop(PLL)is designed.(4)The hardware driver circuit based on stm32f103vet6 control chip is analyzed in detail,including rectifier circuit,switching power supply circuit,intelligent power module(IPM)integrated circuit and phase current and bus current sampling circuit.(5)The software flow of PMSM rotor initial position detection,dq axis inductance parameter calculation,sliding mode control and phase-locked loop is designed.(6)Finally,the experimental platform,debugging program and experimental data are built to verify the feasibility and practicability of the method.