Research Of Deadbeat Current Controlled PWM Rectifier

PWM converter has the advantages of sinusoidal input current, unity power factor, adjustable DC voltage and bidirectional energy flow. Conforming the trends of "green power transformation" and "Made in China 2025", PWM converter has been widely applied in various fields of national economy and received wide attention and research.In this dissertation, three-phase voltage-type PWM rectifier is the research plant, the main work of the dissertation includes establishment of system model, study of control methods, design of software and hardware and analysis of simulation and experiment results.The operating principle and common topology of PWM rectifier are analyzed. The mathematical model in three-phase static coordinate system and synchronously rotating coordinate system are deduced. This dissertation investigates the principle of single synchronous reference frame software phase locked loop and double second order generalized integrator software phase locked loop. The parameter tuning method for the controller of PLL is studied. The application of SVPWM technology in PWM rectifier is introduced, meanwhile, some common control strategies of voltage-type PWM rectifier are discussed. Based on dq mathematical model of the system, dual closed loop structure is adopted and the loop controllers are designed. The outer voltage loop employs PI controller, to overcome the shortcomings of conventional deadbeat predictive current control, inner current loop adopts a modified deadbeat control strategy which applies repetitive controller to predict the reference current. The proposed strategy improves forecast accuracy and enhances the stability of the current loop. On Matlab/Simulink platform, the simulation model of whole system is established. Two types of software phase locked loop and the improved deadbeat current control strategy are verified by simulation.The dissertation designs the hardware and software of three-phase voltage source PWM rectifier. For hardware part, sampling, regulation, driving and protection circuit are designed, parameters of main circuit are also selected; for software part, TMS320F2812DSP of TI is employed as the master controller, based on the thought of modular programming, the flow chart of software is provided.An experimental platform of three-phase voltage-type PWM rectifier is established and debugging for functional modules is conducted. The dynamic and steady state waveforms of improved deadbeat control and conventional PI are provided. Finally, comparative analysis and conclusion are made for improved deadbeat control and conventional PI.