最小原边通态损耗高压输入多谐振推挽变流器

为了提高新型燃料电池能源系统能量转化传递的效率，延长燃料电池本体寿命，提出了一种最小化原边通态损耗的高压输入软开关多谐振推挽变流器。该变流器继承了传统推挽变流器和传统LLC多谐振变流器的全部优点，可用于低成本、高效高功率密度场合，且其原边所有主开关管上的电压应力均为输入电压，故较传统推挽变流器更适用于高压输入的场合。此外该拓扑还通过将原边电流均分至2个推挽支路的方式将原边通态损耗降为传统推挽变流器的一半，提高了转换效率，因而该新颖变流器非常适合作为燃料电池系统中后级单向宽范围输入的高效率直流电源。在详细分析了该变流器的工作原理和关键参数的设计方法后，以一台1 kW的实验样机验证了该拓扑的可靠性和有效性。样机的满载效率达到了97%。

High Voltage Input Zero Voltage Switch Multi-resonant Push-pull Topology With Minimized Conduction Loss for Primary Side

To effectively control fuel cell system energy flow, improve system efficiency and lengthen fuel cell’s lifespan, a novel push-pull type multi-resonant dc-dc converter with minimized conduction power loss for primary side was proposed. This converter possesses both advantages of conven- tional push-pull converter and LLC multi-resonant converter, meanwhile primary switches only sustaining input voltage stress. Thus it is favorable to high line input applications. In addition, primary resonant current of the proposed converter can be halved and each half is carried by a push-pull branch, hence primary conduction loss decreases to half of that of conventional push-pull converter. Therefore, the proposed converter is very suitable for uni-direction downstream DC-DC conversion for fuel cell system applications, where characteris- tics of wide input range and high efficiency are of priority. After the detail operation principles and converter’s character- istics being presented, the validity and applicability were also verified by a 1 kW prototype, while the maximum efficiency reached 97%.