A New High Gain LLC Resonant Converter with Self Voltage Equalization Capability
LLC resonant converters have the advantages of low switching losses and high operating efficiency,but the voltage gain adjustment range is limited by the switching frequency and transformer turn ratio,which cannot meet the needs of application scenarios of photovoltaic microgrid systems.For this reason,this paper proposes a high gain LLC resonant converter with frequency conversion control.This converter changes the rectification network structure of the traditional full bridge LLC to make it have higher boosting ability and reduces the voltage stress of the high-voltage side device to half of the output voltage,better adapting to high voltage situations.It firstly provides a detailed analysis of the working principle and self voltage equalization principle of the converter operating in under-resonant mode.Secondly,it derives the voltage gain of the converter and the voltage stress of the device.In addition,a closed-loop controller is designed using the small signal model of the converter to achieve voltage closed-loop.Finally,it builds a 650 W experimental prototype,and the correctness of the theoretical analysis is verified.
high gainresonant converterlow turn ratioself voltage equalization
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