Research On PWM Rectifier Based On Variable-frequency Power Supply

The traditional diode rectifier and phase controlled recifier have become a usual transform form in variable-frequency power supply because of their simple structure and ripe technology.However,with the rapidly development of the green energy technology,the electronic and the magnetism disturb and the harmonic pollution from the un-controlled rectifiers have become a serious problem.So the PWM rectifier is becoming a new and hot technology in electric power research.PWM rectifier has so many advantages such as making the grid current approach to sine wave,grid power faceor next to 1,four quadrant circulate,rapid motion response,power duplexing teansfor,DC voltage controllable,load disturb resistible and so on,and it is getting a much better application.The paper introduces the theory of three-phase voltage source PWM rectifer in details and deduces the mathematic model in three-phase static coordinate,two-phase static coordinate and two-phase rotary coordinate. Besides,it analyses current control strategy intensively for PWM rectifier, and discusses indirect current control and direct current control in the three different coordinate.Aimed at the dual loops control,voltage outer loop and current inner loop,generally adoped in the control system design of voltage source PWM rectifier,design method of current loop and voltage loop are given.The paper analyses the space vector pulse width modulation (SVPWM) contrasting with the sine pulse width modulation(SPWM). Then the current control strategy based on the space vector pulse width modulation with constant switch frequency is introduced.The hardware circuit design of the control system and the parameter selection of the three-phase voltage source PWM rectifier in variable-frequency power supply are also be discussed.Power Electric toolbox offered by Matlab/Simulink is used to do the simulation experiment in the simulink environment on the foundation of the theory analysis,and the simulation results confirm the exactness and feasibility of the system,and this paper will offer the practical value for PWM rectifier in the research and development.