Research Of Flux Weakening Speed Regulation System Of Permanent Magnet Synchronous Motor Based On Model Predictive Control

Permanent magnet synchronous motor has the advantages of high power density and wide speed regulation range.It is widely used in innovation and industrialization fields such as energy-saving and new energy vehicles,military engineering equipment,high-grade CNC machine tools and so on.As a key core component of industrial manufacturing,its power density multiplication,speed regulation range expansion and safety performance enhancement are one of the important means to realize China’s high-end equipment innovation,core technology breakthrough and basic supporting capacity enhancement.This paper takes the internal permanent magnet synchronous motor as the research object,integrates the model predictive control method,carries out the research on flux weakening speed regulation strategy,improves the motor system speed and enhances the stability of the control system.Firstly,the types of existing AC drive motors and the principle of their control strategy are discussed in detail.Taking the built-in PMSM with better magnetic field weakening performance as the research object,this paper expounds the coordinate transformation,pulse width modulation technology and control architecture of vector control system.In order to solve the problems of complex PI（proportion integral）parameter setting,integral gradual change and over saturation of vector control strategy,this paper introduces model predictive control strategy,and discusses the key links such as predictive model design,cost function construction,optimal solution,closed-loop feedback correction and delay compensation.Secondly,the built-in PMSM speed-up constraint model and the existing flux weakening control strategy are analyzed in detail.Taking the dynamic voltage limit ellipse and static current limit circle as constraints,the speed-up operation area of the motor is divided,and the Lagrange multiplier method is introduced to solve the speed-up constraint optimization problem.Matlab / Simulink theory is used to analyze the characteristics of the existing speed-up control platform and the direct feedback control strategy.In order to have both the current response speed and the dynamic regulation ability of back EMF,a flux weakening control strategy of permanent magnet synchronous motor based on model predictive control is proposed in this paper.The reference current of DQ axis is given by the look-up table method.On the basis of maintaining the feedforward flux weakening response speed,the complex calculation problems caused by the direct calculation method and the dependence on motor parameters are solved;The dynamic flux weakening parameters are designed by voltage feedback to enhance the dynamic regulation ability of back EMF;Predictive current control is applied to the closed-loop design of current loop to solve the problems of complex PI parameter adjustment and integral saturation,and further improve the current response speed of inner loop.Finally,a three-phase built-in PMSM drive control platform is constructed to carry out steady-state and dynamic experiments under different working conditions.Experimental results show that the proposed strategy has good steady-state performance and dynamic performance.It not only has strong anti-interference ability against load sudden change,but also has stable output torque and small torque ripple.