新型LLC+LC双谐振软开关变换器研究

Research on novel LLC+LC double resonant soft switching converter

针对LLC谐振变换器在负载变化时出现容性电压导通,带来关断损耗大效率低等问题,该文提出一种采用有限双极限控制技术方案,在LLC谐振变换器的基础上增加一个LC辅助谐振电路,并在开关器件上并联电容,构成新型LLC+LC双谐振软开关变换器。该文先介绍新型变换器的工作模态,建立数学模型,分析软开关特性,再进行参数设计,最后通过实验验证,证实关断损耗小、传输效率高。

For the load disturbance of the LLC resonant c onverter,a capacitive turn-on voltage is occurred to the switches,leading to a high turn-off loss and low efficiency.Therefore,a limited double limits based control strategy is proposed in this paper.A new LLC+LC double resonant soft switching converter is designed by adding a LC auxiliary resonant circuit and paralleling a capacitor to the switch.The operating modes,mathematic model and soft switching characteristics is analyzed firstly.The design method of the circuit parameters is also discussed.The proposed converter is verified to have low turn-off loss and high transmission efficiency by the experiments.