Research On Control Of SVPWM Rectifier Based On Advanced PID Algorithms

With the increasing depletion of global fossil energy and the increasingly serious environmental problems,more and more attention has been paid to the development and utilization of new energy sources.The vigorous rise of wind power generation,photovoltaic power generation,new energy vehicles,fuel cells and other industries has promoted the development of power electronics technology.Three-phase voltage source PWM rectifier,as a common topology of high-power converter,has the characteristics of non-linearity,strong coupling and time-varying.So it needs excellent algorithms to control.In view of the irreplaceable advantages of traditional PID control,this thesis combines PID control with intelligent algorithms to make the rectifier control system have fast response,high stability,good control accuracy and strong anti-interference ability.The main work of this theies is as follows:Firstly,the basic principle of PWM rectifier is introduced in detail and the advantages of fully controlled rectifier are analyzed.Based on the topological structure of three-phase voltage source PWM rectifier,the mathematical model of the rectifier in three-phase static coordinate system is converted into two-phase rotating coordinate system by using coordinate transformation principle.Secondly,based on the established mathematical model of rectifier,the PI coefficients of voltage loop and current loop are deduced according to the design principle of parameters of typical system.To solve the problem of slow step response of DC voltage,an improved single neuron adaptive PID voltage controller is designed.The value of neuron coefficient K is adjusted adaptively according to the variation of deviation,so that the overshoot and response speed can reach comprehensive optimum.In order to improve the anti-interference ability of the rectifier,the PI parameters of the current loop are adjusted online by using the fuzzy rules so that the DC voltage can return to the steady state rapidly when the load disturbs.Based on the above research of control system,the basic principle and algorithm implementation steps of SVPWM technology are further elaborated.Thirdly,the simulation model of rectifier is built in the environment of Matlab/Simulink and the simulation results are analyzed systematically.The simulation results show that the neuron weight coefficients of the improved algorithm can be adjusted according to the working conditions and quickly converge to the stable value,so that the voltage step response can achieve rapid response when the overshoot is small.When load disturbance occurs,PI parameters of the current loop are adjusted adaptively according to the rules to increase the response speed of the current loop to reduce the voltage drop on the DC side and make it return to steady state quickly.The simulation results show that the advanced PID algorithms have better control effect than the ordinary PID algorithm.Lastly,a three-phase voltage source PWM rectifier control platform is designed based on TMS320F28335.The hardware includes the selection of components and the design of modules of the control circuit;software includes the design of main program,timer interrupt program and related subroutines.