Research On Design And Control Of Multi-Converters Combined System

Since the 18th National Congress of the Communist Party of China,with the development of economic globalization,power electronics technology has become more and more important in People’s Daily life.The DC high voltage conversion technology has been widely used in aviation power supply,satellite detection,high and low voltage remote power transmission,DC microgrid system,and Marine electric power remote power supply system.However,blindly improving the voltage withstand level of converter components is contrary to the current trend of power electronic converter miniaturization,and brings great challenges to the insulation,component selection and stability design of the converter system.In order to solve the above problems,the input-series and output-Parallel DC/DC combined system based on full-bridge converter is analyzed in detail in this paper.The main advantages of multi-converter combination system are:high voltage resistance,strong reliability,but also has a fast dynamic response and other characteristics.Research on control strategy of multi-converter combined system has far-reaching significance and influence on stable operation of the system,power equalization among modules and improvement of voltage withstand level of the system.Firstly,by analyzing the characteristics,advantages and disadvantages of each basic topology,this paper chooses the phase-shifted full bridge as the basic topology.Then,through the analysis of the basic principle and main characteristics of the phase-shifting full bridge,the various modal process of the phase-shifting control circuit,the realization method of Zero Voltage Switch and the cause of the loss of the secondary side duty ratio are determined.After that,the component parameters of the module unit of the phase-shifting full bridge converter are designed.Including high-frequency transformer design,output filter inductor and resonant inductor design,power device selection,input and output capacitance selection,etc.Second,Topology of input-series and output-Parallel combined converter system,Input Voltage Share between modules and Ouput Current between modules in the system Share).Taking full-bridge converter as the basic module,multiple modules are combined to form inputseries and output-Parallel system.Aiming at the problem of unbalanced Input power or Output power among modules in this combined system,A Duty cycle-Model Predictive Control strategy based on Duty Cycle is proposed.And through mathematical modeling analysis of the basic full-bridge converter module and the input-series and output-Parallel full-bridge converter system composed of multiple modules,and then complete the parameter design of the proposed control strategy control loop.Thirdly,according to the proposed Duty cycle-Model Predictive Control strategy,The simulation model of input-series and output-Parallel phase shift full bridge converter system composed of two modules and several modules was built respectively,and staggered control was adopted to reduce the Output current ripple.Then,when the parameters between modules are consistent and the parameters between modules are inconsistent,the simulation analysis of input voltage step and load mutation is carried out.Finally,on the basis of the above work,the hardware and software design of input-series and output-Parallel combined converter is carried out.Then a prototype experimental platform of input-series and output-Parallel combined system based on full-bridge converter was built and verified by experiments.Finally,through simulation and experimental results:The Duty cycle-model Predictive Control(MPC)strategy adopted in this paper is effective in realizing input-series and The Input Voltage Share of the output-Parallel combined converter is well proved.