基于SiC器件的隔离双向混合型LLC谐振变换器

Isolated Bidirectional Hybrid LLC Converter Based on SiC MOSFET

针对传统双有源桥型直流变换器的软开关范围窄、开关频率低等问题,该文提出一种隔离双向混合型LLC谐振变换器,适用于可再生能源分布式发电系统的储能结构中。在不增加使用额外器件的条件下,通过不同调制方案转换,该变换器可以在全桥变换器、双半桥变换器和单半桥变换器三种工作模式下混合运行。在变压器励磁电感协助下,三种不同工作模式无论正向或反向运行,均可实现所有开关管的零电压开通,以减少开关管的开通损耗,实现高效的双向功率转换和宽电压增益调节,提高轻载下的变换器工作效率,且三种工作运行模式可以平滑、稳定地过渡切换。最后搭建一台基于SiC器件的800W样机,实验结果证明了该变换器拓扑及其控制方法的可行性、有效性和稳定性。

The traditional dual active bridge DC-DC converter has the problems of narrow switching range and low switching frequency. Therefore, an isolated bidirectional hybrid LLC resonant converter is proposed for the energy storage structure of renewable energy distributed power generation systems. The converter can operate in three modes of full-bridge LLC converter(FLLC), dual-phase half-bridge LLC converter(DLLC) and single-phase half-bridge LLC converter(SLLC) by different modulation schemes without using additional devices. With the help of the magnetizing inductance of transformer, three different operating modes can realize the zero-voltage switching turn-on for all the MOSFETs on primary and secondary sides, regardless of the forward or backward operation, which can reduce the turn-on loss of switches, achieve high-efficiency bidirectional power conversion and wide voltage gain adjustment, and improve the efficiency of the converter under light load. And these three operating modes can be smoothly and stably transitioned. Finally, an 800W experimental prototype based on Silicon Carbide(SiC) devices is built. The experimental results verify the feasibility,effectiveness and stability of the proposed circuit topology and its control method.