Simultaneous-supplying Full-bridge Buck Dual-input DC-DC Converter Mode Distributed Generation System

New energy power generation has the advantages of green sustained development,cheap and rich resources.Distributed generation system supplied by single kind of new energy is characterized by unstable,discontinuous and sensitive to climatic change,and the practicability are not very satisfactory.A distributed power generation system combined several kinds of new energy has higher reliability and better leverage on new energy sources usage,which has received the close attention in the field of n ew energy generation technology.Based on the discussion of traditional single-input DC-DC converter mode distributed generation system and two-stage multi-input DC-DC converter mode distributed generation system,a simultaneous-supplying full-bridge Buck dual-input DC-DC converter mode distributed generation system,and the energy management control strategy are proposed.The circurit topology,characteristic of steady principle and design criteria for the key circuit parameters were deeply analyzed.Simulation and prototype experiment has been carried out,and important conclusions were obtained.The circuit topology is constituted of a simultaneous-supplying full-bridge Buck dual-input DC-DC converter and line-frequency polarity reversal bridge,and has the advantages such as flexible control of the input source,electrical isolation between input and ouput,strong voltage matching capability.The maximum power output energy management with the output current feedback and output filter capacitor current feedforward of the proposed grid-connected inverter,and the master-slave power energy management with a sigle loop control of output voltage of the off-grid inverter were deeply analyzed.The small signal models were established and the compensators of the system were also designed.The proposed control strgtegys realize the prior use of new energy and the control of output waveform.By analyzing the circuit topology of the inverter,it was found that putting output filter in front of line-frequency polarity reversal bridge helps to reduce voltage stress and high frequency loss of the reversal bridge,and can also reduce the strength of electromagnetic interference(EMI)of the system.Analyzing the steady principle waveforms and operation modes with resistance-capacitance load of the proposed off-grid inverter,the steady principle characteristics of energy feedforward and energy feedback were both obtained,and the results show that the off-grid inverter can adapt reactive load.Parameter design rules of the input filter capacitor,high frequency transformer,LCL output filter and power switch were derived,which lay a theoretical foundation for the simulations and off-grid prototype experiment of the simultaneous-supplying full-bridge Buck dual-Input DC-DC converter mode distributed generation system.A off-grid prototype of 1.2kVA PV-Wind simultaneous-supplying full-bridge Buck dual-Input DC-DC converter mode distributed generation system were designed.The experimental results of the steady-state and dynamic test show that the system has excellent performances such as flexible control of the input source,electrical isolation between input and ouput,strong voltage matching capability,smooth transition among different modes,good dynamical response,which validates the feasibility and advancedness of the proposed circuit configuration and management control strategy.