Research On DAB Multi-Port DC/DC Converter

With the shortage of natural energy sources such as oil and natural gas in the world,the natural resources available to humans on the earth are seriously threatened,and more scientific research forces on new energy power generation technologies such as solar photovoltaic power generation technology are bound to become a situation.At the same time,in the face of a growing number of distributed power supplies,how to apply them better,more flexibly and more efficiently,and solve their access problems,more scholars will work on DC/DC converters study.In the microgrid,there are various control methods for improving the efficiency of multi-port DC/DC converters.This paper is mainly based on the multi-port mathematical model,which realizes the elimination of the return power during the zero-voltage turn-on of the switch and the power conversion process.These two goals are to optimize the functionality of the multi-port DC/DC converter circuit.This paper mainly studies the multi-active bridge(MAB)structure and multi-port DC/DC converter.Firstly,the DAB converter is selected for modeling,then the two control strategies of the DAB converter are analyzed.Single phase shift control and three phase shift control indicate that the single phase shift control can not realize the zero voltage soft switch of the switch tube under light load conditions when the secondary DC bus voltage is different,and the power return phenomenon cannot be eliminated.When the converter adopts the three phase shift modulation strategy,the voltage and current and the active power of the converter are analyzed,and the relevant simulation results are verified.Finally,the multi-active bridge structure is modeled,and the conclusion that it can be decomposed into multiple dual active bridges(DAB)is analyzed.Power decoupling analysis is then performed on the MAB converter,and PI control is used to maintain voltage balance.In order to realize zero voltage turn-on and eliminate power reflow on both sides of the switch,the principle of zero-voltageturn-on and power-return elimination of the converter is analyzed.According to the current direction when each switch is turned on,the converters are calculated.The tube realizes the constraints of zero voltage turn-on and power reflow elimination,and also extends this conclusion to the MAB converter,and performs three-port correlation simulation to verify.At the end of the paper,the simulation of the three-port DC/DC converter in the island state is built,and the targets such as photovoltaic energy storage and DC load cell flow are realized.The multi-port access is realized through the relevant control strategy.Finally,the simulation and results are given according to several working conditions.