Research On Deadbeat Predictive Power Control Strategy Of PWM Rectifier

Three phase voltage source pulse width modulation(PWM)rectifier has advantages of bidirectional power flow,sinusoidal current,controllable power factor and good DC link voltage regulation capability,etc.Therefore,it has been widely applied in microelectronics,home appliances,electronic ballasts,battery charging,DC motor drive,power conversion,etc.At present,most of the research on predictive power control strategy of PWM Rectifier is to design the closed-loop control system on the premise of balancing the power grid and system health,seldom considering the overshoot phenomenon of DC side voltage,and the problem of system control accuracy degradation caused by the grid voltage distortion and system parameter mismatch is also rarely involved.Therefore,in this paper,the voltage source PWM rectifier is taken as the research object,focusing on the problem of DC side voltage overshoot,the problem of system control accuracy degradation caused by grid voltage distortion and system parameter mismatch.The research content of this paper is as follows.Firstly,in order to solve the problem of voltage overshoot on DC side,a fuzzy PI compound control(FPCC)scheme is proposed in this paper to replace the traditional PI controller of voltage outer loop.Meanwhile,the method of combining fuzzy controller and PI controller is used to design the voltage outer loop.Fuzzy control rules are used to adaptively adjust the parameters of PI controller on-line,which overcomes the shortcomings of traditional PI controller that cannot dynamically adjust PI,improves the dynamic response speed of the system and solves the problem of voltage overshoot at DC side.Secondly,a predictive direct power control(PDPC)algorithm based on current sliding mode observer(CSMO)is proposed to solve the problem of control accuracy degradation caused by system parameter mismatch.The current sliding mode observer designed to compensate the disturbance error on-line when the system parameters are mismatched,which solves the problem that the control accuracy decreases due to the system parameters mismatching.Thirdly,a deadbeat predictive power control(DPPC)method based on voltage predictive observer(VPO)and discrete-time current disturbance observer(DCDO)is proposed to solve the problem of system control accuracy degradation caused by unbalanced grid conditions and parameter mismatch.The proposed voltage predictive observer can not only accurately estimate and separate the positive and negative sequence components of unbalanced grid voltage,but also predict the grid voltage at the next sampling time.The proposed discrete-time current disturbanceobserver can compensate the system disturbance when the inductance parameter changes,solve the problem that the control accuracy decreases due to the inductance mismatch,and predict the grid current at the next sampling time.This method can effectively control the PWM rectifier when the grid is unbalanced and the parameters are mismatched.Finally,through the stability analysis and MATLAB simulation analysis of the designed method,the analysis results verify the effectiveness of the proposed method.