变压器串-并联LLC+Buck级联DC-DC变换器的均流特性

Current-sharing characteristic of converter composed of LLC with series-parallel transformer and interleaved Buck

研究适用于高压/宽电压范围输入、低压/大电流输出应用场合的高功率密度/大功率级联DC-DC变换器拓扑,采用两级结构.前级为定频/开环工作的变压器串-并联结构的LLC谐振变换器,后级为闭环工作的交错并联Buck电路.分析在前级LLC变压器励磁电感与匝比以及后级Buck占空比等参数不一致的情况下,级联DC-DC变换器工作在3种不同的工作模式,研究该变换器在不同工作模式下均能取得较好的均流特性.通过电路仿真与1kW全砖实验样机,验证了该级联变换器拓扑结构具有良好的自动均流特性,适合应用于高功率密度/大功率DC-DC电能变换场合.

A high power density and high power DC DC converter topology was analyzed,which is a two-stage structure and suitable for high voltage and wide voltage input,low voltage and high current output application.The first stage of the converter is LLC resonant converter with series-parallel transformers working in fixed-frequency and open-loop mode,and the later stage is the interleaved Buck working in closed-loop mode.The three operating modes and the current sharing characteristics for the converter were analyzed under the conditions of different magnetizing inductance,turns ratio and duty cycle.The simulation and experiment show that the converter topology has good current auto-balance characteristics and is suitable for high power density and high power DC DC power conversion application.