一种两级式隔离型双向DC/DC变换器的分析与设计

Analysis and Design of Two-stage Isolated Bi-directional DC/DC Converter

提出了一种两级式隔离型双向DC/DC变换器,该变换器包含一个闭环的前级DC/DC变换器和一个开环的后级LLC谐振变换器。当能量从低压直流母线传输到高压直流母线时,变换器等效为Boost变换器+全桥倍压LLC谐振变换器;当能量反方向流动时,变换器等效为半桥LLC谐振变换器+Buck变换器。通过分析变换器工作原理与设计要点,提出了以效率为目标的中间直流母线电压优化方法,并研制了1台12 V/336 V、1 kW的样机,其优化后的中间直流母线电压额定值为50 V。样机实验结果验证了所提变换器的良好工作性能。

A two-stage isolated bi-directional DC/DC converter is proposed. The converter is composed of a regulated front-end DC/DC converter and a unregulated back-end LLC resonant converter. When the energy flows from low-voltage DC bus to high-voltage DC bus, the converter is equivalent to Boost converter cascaded full bridge LLC resonant converter with output voltage doubling. When the energy flow is reversed, the converter is equivalent to half bridge LLC resonant converter cascaded Buck converter. The operational theory and key design point are analyzed, and efficiency-oriented optimization method of middle-voltage DC bus is proposed. A prototype of 1kW, 12 V/336 V is build,and the optimum nominal voltage of middle-voltage DC bus is 50 V. The experimental results verify the good performance of the proposed converter.