| In order to overcome the problems existing in the distribu ted generation itself, DC micro-grid has been used more and more widely. As a new type of grid architecture, DC micro-grid usually contains dc bus, distributed power supply, energy storage devices, power converter, etc. It can both satisfy the requirement of power quality for the load and guarantee the safety of power supply. Hybrid energy storage system consists of battery and super capacitor can meet the performance index of dc micro-grid better, scientific and reasonable design of the interface unit among distributed power supply, energy storage devices and DC micro-grid plays a very important role in the reasonable and efficient use of renewable energy. This subject aims at a three port DC/DC converter for hybrid energy storage applied in the DC micro-grid, studies the work mode, power transmission capacity, decoupling control and energy management and so on.Firstly the topology of the converter is determined, the work mode is analyzed with the Y equivalent model and the power transmission capacity is analyzed with the Δ equivalent model, and the influences of different factors on the power transferred among ports is studied; Secondly the small signal model of the converter is established on the basis of the average-current method, the coupling relationship and decoupling method principle is analyzed with the small signal model, and the soft switching feature and zero power control are also studied; Besides, energy management strategies under different work mode of the DC micro-grid is designed and its validation is verified in the simulation software PLECS.Finally, a experiment platform of the three-port DC/DC converter for hybrid energy storage is built, the hardware circuit and the three-windin high frequency transformer are designed, the flow diagram of the main program and the interrupt subprogram and the phase shift PWM generation method are also given, the control program is written according to the circuit structure and the control strategy based on the STM32F407 controller, the correctness and effectiveness of the proposed control strategy are verified. |
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