Optimization Control And Design Of Bidirectional Full-Bridge LLC Resonant Converter

In recent years,bidirectional DC/DC converters have been widely used in smart intelligent microgrid,energy storage system,electric vehicles,uninterruptible power supply(UPS)and so on.There are varieties of bidirectional DC/DC converter topologies and control methods,which have their own characteristics.Therefore,it is of great practical significance to study and improve the performance of bidirectional DC/DC converters.The bidirectional LLC resonant converter has broad application prospects due to its characteristics of high efficiency,wide voltage gain and bidirectional power flow.In this paper,bidirectional full-bridge LLC resonant converter is selected as the research object,the advantages and the operation principle of the converter are analyzed in detail.Combined with the existing control method,two optimization control methods are proposed,namely unilateral dual-phase-shift(DPS)control and synchronous rectification control.The converter can operate either in Boost or Buck mode.All the switches can realize soft-switching,and the bidirectional power flow can be realized under two optimization control methods which are proposed above.The principle of the two optimization control methods is analyzed in detail in this paper.And the improvements of the two control methods compared with the existing control methods are introduced,which shows the advantages of the improved control method.The detailed operation principle,control strategies,voltage gain expression,soft-switching characteristics and design of parameters are analyzed,which base on the built fundamental equivalent model.And the feasibility of the two optimization control methods is analyzed and verified theoretically.A simulation which is based on bidirectional LLC resonant converter is built in PSIM to verify the voltage gain and soft-switching characteristics of the two proposed control strategy(,and the feasibility of the control method is preliminarily verified).The hardware design of each part of the bidirectional full-bridge LLC resonant converter and the software programming based on TI DSP TMS320F28335 are carried out.On this basis,the experimental prototype is built).The correctness and feasibility of the theoretical analysis and simulation research are further verified by experiments.