Research On Predictive Control Of Surface Permanent Magnet Synchronous Motor Based On Disturbance Compensation

Permanent Magnet Synchronous Motor(PMSM)is widely used in electric vehicles,aerospace,rail transit and other fields due to its high efficiency,strong reliability,and high power density and other excellent characteristics.However,PI control has been unable to meet the requirements of high-performance control.Therefore,in order to achieve better control effects,predictive control has received close attention due to its fast dynamic response and good tracking performance.This thesis takes surface-mount PMSM as the research object to conduct in-depth research on predictive control strategies.The main reasearch is as follows:(1)The thesis introduces the basic structure of PMSM,and then establishes mathematical models under three-phase stationary coordinate system,two-phase stationary coordinate system and two-phase rotating coordinate system based on the principle of coordinate transformation,and analyzes the principle and realization process of voltage space vector pulse width modulation technology in detail.Then the common vector control strategy is explained,and the simulation experiment of PI vector control system is carried out based on id = 0,which lays the foundation for further research on predictive control.(2)According to the discrete mathematical model of PMSM,the deadbeat current predictive control algorithm is designed,and the reasons for the time delay caused by deadbeat predictive control and the sensitivity to the mismatch of resistance,inductance and flux linkage parameters are analyzed in detail.Through the simulation analysis of the parameter change of 0.5 times and 2 times,it is verified that when the inductance and flux linkage parameters are disturbed,the influence on the system is great,while the resistance disturbance is not very sensitive.In order to solve the problem of control delay and improve current tracking accuracy and system stability,a two-step prediction method with a correction link for predictive current error is proposed,and simulation results are analyzed at the same time.(3)Aiming at the problem of parameter mismatch,two disturbance compensation methods are proposed based on improved deadbeat current predictive control.The first method compensates for the current loop output by constructing a sliding mode disturbance observer to observe the voltage disturbance in real time,and replaces the sign function in the traditional exponential reaching law with a saturation function to weaken the system chattering phenomenon.The second method is to design the discrete extended state observer(ESO)to obtain the observed values of the current in the quadrature-direction axis and the system disturbance to correct the reference current and voltage respectively.Then modeling on MATLAB/Simulink to verify the feasibility of these two compensation strategies,and summarize and compare their respective characteristics.These two compensation strategies can effectively suppress the current tracking error and reduce the harmonic content of the stator current.However,the sliding mode compensation control has system chattering.Compared with ESO,the observer design is slightly more complicated,and ESO only contains the parameter of inductance,and only the influence caused by the disturbance of inductance parameter needs to be considered.In addition,it not only compensates the voltage,but also corrects the reference current,and the algorithm robustness is improved.(4)The model predictive control is applied to the speed loop to replace the traditional PI controller to enhance the performance of the motor.In addition,considering that load disturbance will affect system control performance,a model predictive speed control strategy based on load disturbance compensation is proposed.Internal model control observer is constructed to observe the motor load disturbance,which is converted into torque current for feedforward compensation of the output value of the speed loop.The verification and analysis are carried out in Simulink environment,and the simulation results show that the proposed method can effectively improve the system dynamic response and anti-load disturbance ability,and improve the control effect of the overall system.