一种应用于电动汽车快速充电站的高频隔离双级功率变换器

A High-Frequency-Isolation Two-Power-Stage Converter Applied in Electric Vehicle Fast Charging Station

提出了一种新型可应用于电动汽车直流快速充电站的高频隔离型(high-frequency-isolation,HFI)双级功率变换系统结构,该变换器结合了前端三电平Buck变换器与后端LLC谐振变换器的双重优点。三电平Buck变换器开关管承受的电压为直流母线电压的一半,适合应用在高压大功率的场合,后端采用LLC谐振变换器可以实现高频电气隔离,同时具有实现逆变桥开关管零电压开通(zero-voltageswitch,ZVS),二次侧整流桥二极管零电流关断(zero-currentswitch,ZCS)的优良特性。文章详细介绍了该新型系统结构的工作原理及特性,并介绍了该两级系统结合后的新特性,并提出了变换器的均流均压控制策略。最后,搭建了一套20 k W,输入电压760 V,输出电压200~500 V的实验装置。通过实验验证了系统结构的可靠性。

Combining advantages of front-end three-level Buck converter and back-end LLC resonant converter, a novel high-frequency-isolation （HFI） fast-charging DC port with two-power-stage structure is proposed in this paper. LV rating power switches are adopted for half-voltage stress of total DC bus. The proposed system structure can be suitably applied in HV and high power condition. High-frequency electrical isolation is realized with back-end LLC converter with good characteristics of zero-voltage switching （ZVS） for inverter side and zero-current switching （ZCS） for rectifier side. Principles of the proposed fast-charging port topology are studied, and the new features and characteristics are analyzed. Control strategy of constant-current and constant-voltage charging modes are analyzed. Finally, a 20kW prototype with 760V input voltage, 200-500V output voltage is built. Experimental results are presented to verify validity of the proposed fast charging DC port system.