| Battery energy storage system has some advantages. For example, small size,light weight, long life cycle, relatively small investment, flexible installation, etc.In the new energy power generation grid network and electric vehicles are widelyused. With the battery energy storage system capacity expands, scalable modular,high power density and high charge-discharge efficiency of the bi-directionalconverter structure and control strategy become a trend.This paper presents the main work that is bi-directional three-phase AC-DCconverters and bidirectional DC-DC converter.They are two-part set of charging anddischarging control in one variable flow structure and its distributed control strategy.Bi-directional AC-DC converter topology chooses the three-phase bridge AC-DCconverter, three-phase AC-DC converter has higher DC output voltage andutilization rate, bi-directional DC-DC topology chooses DAB (Dual-Active-Bridge)with high frequency isolated transformer. DAB circuit has symmetry structure,simple control, high charge-discharge efficiency and power desity, which is suitablefor large and medium power application.The first stage double-phase AC-DC converter is based on d-q coordinatetransformation’s space vector modulation SVPWM control to achieve unity powerfactor rectifier and inverter, post-stage circuit DAB is used the improvement ofsmall-signal-based phase shift control model based on the traditional phase-shiftcontrol method to improve the ripple of the voltage of the battery side and thesyetem response speed.Matlab/Smulink simulation and experiment results demonstrate that theproposed bi-directional converter structure and its distributed control strategycorrectness and validity, and the bi-directional converter have these advantages: lowharmonic pollution, high power density and high charge-discharge efficiency andreducing the battery side voltage ripple, improving the battery’s life. |
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