Research On Current-Fed And Voltage-Source Half-Bridge Based Bidirectional DC-DC Converter

With the increasing emphasis on energy and environmental issues worldwide,photovoltaic power generation has attracted the attention of the public as an effective form of solar energy utilization.As an important component of photovoltaic power generation,household photovoltaic power generation has also received widespread attention at home and abroad.In order to suppress the bus power fluctuation caused by the uncertainty and randomness of solar power generation,a small generation and distribution system of household electricity,that is,a household photovoltaic microgrid,came into being.Power conversion system(PCS),as an indispensable part of household photovoltaic microgrids,has an important research significance.Therefore,a high efficiency,high power density and high reliability bidirectional DC-DC converter is studied in this paper.The topologies of commonly used bidirectional DC-DC converters are compared in this paper.Combined with the topology of the current-fed half-bridge bidirectional DC-DC converter and the boost-dual half-bridge DC-DC converter,the current-fed and voltage-source half-bridge bidirectional DC-DC converter topology is proposed.At the same time,it is compared with the existing current-fed half-bridge bidirectional DC-DC converter,which highlights the superiority in efficiency of this topology improvement.The working principle of the current-fed and voltage-source half-bridge bidirectional DC-DC converter is analyzed in detail.Based on the "PWM + dual phase shift" modulation strategy,the expression of the power transfer relationship of the converter is derived and clarified.The condition that the converter can realize soft switching in the full load range is provided,which provides the conditions for the realization of high-frequency of the converter.Based on the working principle and the design index of the bidirectional DC-DC converter,the detailed parameter design,hardware power circuit design and software design of the bidirectional DC-DC converter based on the current-fed and voltage-source half-bridge are carried out.At the same time,according to the completed design scheme,detailed loss calculation is performed to provide a basis for subsequent efficiency optimization of the converter.Based on the theoretical analysis,a steady-state and dynamic simulation of the bidirectional DC-DC converter based on the current-fed and voltage-source half bridge is performed based on the software of Saber.A bidirectional DC-DC converter prototype based on the current-fed and voltage-source half bridge with a power of 1k W and a frequency of 400 k Hz was developed.Based on the prototype,an experimental study based on the basic working principle,soft switching,and control strategy was carried out.The simulation and experiment compared with a single half-bridge current-fed DC-DC converter were also carried out.The correctness of the working principle analysis of the bidirectional DC-DC converter based on the current-fed and voltage-source half-bridge,as well as the correctness of the parameter design and control loop design are verified.