Research On Sensorless Control Of Permanent Magnet Synchronous Motor

With the development of power electronic technology and the deep understanding of Nd Fe B,alnico and other permanent magnet materials and the decrease of price,permanent magnet synchronous motor has the advantages of high energy conversion efficiency,small volume,large energy density,good silent effect and good speed regulation performance.More and more widely used in aerospace,ship propulsion,electric vehicle traction and other production and life,military defense in various fields.In every field of using PMSM,there are high requirements for its speed regulation and precise control.In order to get a better control effect on the motor,the motor control system needs to be closed-loop,and to achieve closed-loop,it needs to obtain the rotor position and speed when the permanent magnet synchronous motor is running.The traditional way is to install position and speed sensors in the motor,but the sensors will also limit the use of the motor in some operation scenarios,in order to solve this problem in this paper,the sensorless control scheme of PMSM is studied.Firstly,according to the different fixing methods of permanent magnet on the rotor,the permanent magnet synchronous motor is classified.The coordinate transformation theory and control theory are introduced,and the control strategy of sensorless control system of PMSM is analyzed;Secondly,according to the structure of PMSM,the mathematical model of PMSM in ABC coordinate system is established,and the model of PMSM in d-q axis system is obtained by using the principle of coordinate transformation.The vector control system model is established by combining the control theory,and the control system simulation model is established by using Simulink to verify the control effect;Then,according to the performance of PMSM at low speed and high speed respectively,different sensorless control methods are established.Among them,highfrequency square wave injection method is used at low speed.In this paper,the method of Fourier decomposition is used to transform the discrete square wave signal into the form of continuous sine fundamental wave and odd harmonic superposition.The current corresponding to the fundamental wave is obtained by using the filter After the response,the continuous signal processing method is used to reduce the sampling frequency and calculation amount;at medium and high speed,the model reference adaptive control method is used,and the control method is simplified according to the control strategy in this paper,and the position sensor free control system with full speed range is established by combining the two control methods organically.The simulation model of the control method is established to verify the feasibility of the control system,which is consistent with the theoretical expectation.Finally,the hardware experiment platform is designed and established,the control code is written,and the feasibility of the control system is tested,which has a good control effect.