Research And Design Of Modular High Power Factor Rectifier

With the development of power electronics,power electronic devices are developing towards to higher frequency,digital,green,and Modules.This thesis develops a modular high power factor rectifier cascaded by a Boost PFC converter and a phase-shifted full-bridge converter.The system adopts parallel flow sharing control,and its internal module adopts mixed control of analog and digital.This thesis establishes the small-signal model of the previous-stage PFC circuit,and derives its transfer function,adopts a double-loop control strategy based on the average current control,and designs the voltage loop and the current loop.For the rear-stage soft-switching phase-shifted full-bridge circuit,a small-signal model was first established,and a dual-loop PID controller with an output voltage outer loop and an inductor current inner loop was designed.However,when using a traditional PID control mode,the theoretically only a specific Near the working point has better control performance.Based on the deep analysis of traditional modeling and control methods,this thesis establishes a linear variable parameter model with input voltage and load as variable parameters,and uses variable parameter extreme value combination to transform it into a polytope model.By analyzing the stability of the vertex and designing the controller,a robust control strategy based on multivariate linear variable parametric model of a soft-switching phase-shifted full-bridge converter is studied.In this thesis,based on the research of the model and control strategy of the high-frequency rectifier system,the design of the prototype is carried out.Firstly,the main circuit parameters of the high-frequency rectifier system are designed,and the peripheral circuit parameters of the analog special chip UC2854 are designed in detail.For the rear-stage soft-switch phase-shifted full-bridge circuit,The hardware design of the voltage outer loop with the digital chip TMS320F28035 and the analog chip UCC28950 as the current inner loop is given.Finally,the structure of the software part of the program control framework and the main program,subroutine flow chart.Finally,the system is simulated in MATLAB.Theoretically verifying the system topology and the feasibility of the control strategy,at the same time,focusing on comparative analysis of phase-shifted full-bridge traditional PID control and robust gain-gain scheduling control.The advantages of robust gain-shift scheduling control are highlighted.An experimental platform is built and a 3.2kW prototype is designed and manufactured.The experimental results show that the power factor of the prototype can reach 0.99 or more,which meets the design requirements.The post-stage soft-switching phase-shifted full-bridge circuit basically realizes zero-voltage turn-on,and the load capacity meets the design requirements.The analog current inner loop digital voltage outer loop controller also has better characteristics.