电力电子牵引变压器中LLC谐振变换器拓扑结构选型研究

Topology Selection of LLC Resonant Converter Applied in PETT

LLC谐振变换器是电力电子牵引变压器(PETT)的关键部分,其拓扑结构的选择至关重要。本文基于理论和仿真分析对比研究了对称半桥、非对称半桥、全桥结构LLC谐振变换器,重点关注其器件选型、电路参数及传输损耗,并给出拓扑结构选择依据;同时,针对非对称半桥、全桥结构LLC谐振变换器展开样机实验研究,结果表明,相对全桥结构LLC谐振变换器,非对称结构具有开关器件损耗低、启动电流冲击小等优点,但是同时存在二次脉动大、谐振电容选型受限等缺点。

LLC resonant converter is the key part of power electronic traction transformer（PETT）, and the choice of its topology is critical. It analyzed the LLC resonant converter with symmetrical half bridge, asymmetrical half bridge and full bridge structure respectively based on the theory and simulation, and focused on the device selection, circuit parameters and transmission loss, and provided the selection basis of its topology. In the experimental stage of prototype, only the asymmetrical half bridge and full bridge structure were studied. The results showed that, comparing to the full bridge structure, the LLC resonant converter with asymmetrical half bridge structure has the advantages of less switching devices loss, smaller starting current and so on, meanwhile, there are two disadvantages, such as large pulse and limited selection of resonant capacitor.