| LLC resonant converter has been widely used in LED power supply,electric vehicle charger,notebook adapter,distributed generation system and so on.But it is not suitable for solar power,wind power,fuel cell power generation and other new energy which has wide input voltage range occasion.The switching frequency range is large,which is not conducive to the design of magnetic components.This paper proposes Boost+LLC resonant converter to use the Boost property of the Boost circuit,which is successfully applied to a wide range of input voltage applications.At the same time the control method was studied to realize the main switches operating with zero voltage switching and secondary rectifier operating with zero current switching.The fixed frequency control is realized,the design of the magnetic component is convenient,the loss of the magnetic component is reduced,and the efficiency of the converter is improved.First,the research of the principle and the gain characteristics of Boost+LLC resonant converter is verified,this paper confirms the feasibility of its application in a wide input voltage range.Then,study the control method and the ZVS derived conditions,according to the design requirements,design the parameters of the Boost+LLC resonant converter.Then analyzes the loss of the converter for each part,the loss of each part are in the permitted range.According to the design requirements of the traditional LLC resonant converter parameters,the input voltage 24~48V,output voltage 400 V,output power 1kW prototype is designed,at the same time the parameters of the Boost+LLC resonant converter experimental platform are built to compare with the design requirements in the same way,confirming that Boost+LLC can achieve a wide input voltage range of full load requirements,and realize the switch of the ZVS and secondary rectifier ZCS. |
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