Research On The Control Strategy Of PWM Rectifier System For Electrolysis

In recent years,due to the serious pollution of the industry,how to efficiently and greenly apply electrical energy has become a major hot spot for research.In the electrolytic plating industry,high-frequency switching power supply can reduce harmonic loss and improve its power utilization rate by using reasonable control strategy,which makes up for the shortage of traditional electrochemical power supply.Therefore,high-frequency switching power supply gradually replaces traditional electrochemical power supply as the core part of electrolytic processing.This paper designs a high-frequency switching power supply with output voltage of 5V and output current of 1000 A.Firstly,considering that pulse width modulation（PWM）rectification technology can reduce harmonics and improve operating power;Soft switching technology can reduce the power switch loss and improve the service life.Therefore,the two-stage topology structure of the front stage three-phase PWM rectifier（VSR）and the rear stage phase-shifting full bridge DC / DC converter（ZVS）is established,and the working principle and mathematical model establishment process of the front and rear stage system are described.Secondly,through the in-depth study of the control strategy,the adverse factors affecting the system stability are analyzed,and the corresponding control strategy is put forward.For the former system,an improved sliding mode control is designed.By strengthening the relationship between the approach rate and the state variables,the control improves the response speed and anti disturbance ability of the system,and solves the problems of high harmonic content and large voltage fluctuation amplitude of the rectifier under PID control.For the later stage system,considering the problems of small stability margin and slow response speed of the phase-shifting full bridge converter system under PID control,the self coupling PID control is introduced.Through the cooperative control of proportional,integral and differential parameters,the contradiction between PID rapidity and overshoot is solved.At the same time,the problems of excessive deviation of the system output voltage from the reference value are also solved,which ensures the stability of the output voltage and improves the control effect.Then,analyzed the stability of the proposed control system.Finally,matlab simulation software is used to verify the feasibility of the proposed control strategy and the accuracy of parameter design,the self coupling PID control and improved sliding mode control are compared with other control strategies.The comparison results show that the control system proposed in this paper has better response speed and anti disturbance ability,and the proposed control system is conducive to the operation mode of low loss and high power.