SiC-MOSFET与Si-IGBT混合开关车载双向充电器中线桥臂设计及控制

Neutral Leg Design and Control of Electric Vehicle On-board Bidirectional Charger Based on SiC-MOSFET and Si-IGBT Hybrid Devices

为增强电动汽车与电网的互动能力,车载双向充电器已成为现研究的热点。设计采用碳化硅金属氧化物半导体场效应晶体管(silicon carbide-metal oxide semiconductor filed effect transistor,SiC-MOSFET)与硅绝缘栅双极型晶体管(silicon-insulated gate bipolar transistor Si-IGBT)相结合,完成了基于双有源桥(dual active bridge,DAB)与三相四线逆变器级联的双向充电系统。通过建立逆变器数学模型分析了不平衡负载下产生分裂电容电压震荡的原因,描述了震荡幅值与负载不平衡度之间的关系,为分裂电容值的选择提供了理论依据。对实际控制系统中存在的延迟,分析使用Si-IGBT构建中线桥臂的可行性,提出了基于虚拟阻抗的双向充电器在不平衡负载下中线桥臂与其他3个桥臂之间的解耦控制方法。并使用10kHz与50kHz开关频率验证了不平衡负载下该控制方法对分裂电容电压震荡的抑制作用。提出该系统在V2G,G2V及V2H这3种不同工作模式下的详细控制策略,通过实验验证了不同模式下的控制策略及中线解耦控制方法的可行性和有效性。并进一步分析该拓扑结构在V2H模式下同时为多个不同住宅提供单相电的可能性,为采用SiC设计类似的电力电子设备提供系统的设计方案及控制方法。

In order to enhance the interaction ability between electric vehicles and the power grid, on-board bidirectional charger has become a research focus. A cascade system with dual active bridge(DAB) and three-phase four-wire inverter based on silicon carbide-metal oxide semiconductor field effect transistor(SiC-MOSFET) and silicon-insulated gate bipolar transistor( Si-IGBT) hybrid devices was proposed. The fundamental reasons for split DC-link voltage oscillation was analyzed by mathematical model of the three-phase four-wire inverter, also the paper provided the relation of voltage amplitude of oscillation with load unbalance factor and provides the guidance for the selection of the DC-link capacitance. Considering the time delay, a decoupled neutral leg control method with virtual impedance was proposed, and the mathematic analysis of lower switching frequency control for neutral leg was provided, the feasibility of the control method with 10 kHz and 50 kHz for the unbalance load was verified. Finally, the paper provided the control strategy for each operation mode, and the feasibility of different control strategies was verified by experiments. Furthermore, the possibility of providing single-phase power for multi-user in vehicle to home(V2 H) mode was analyzed. A system design guide and control method for power electronic equipment realized by SiC switches was proposed.