Abstract：In view of the oscillated bus voltage and imbalanced current distribution caused by imbalanced load condition at vehicle to home (V2H) mode, this paper proposed a 3-phase 4-wire on-board bidirectional charger operating at V2H mode. Split DC-link capacitor is utilized with a neutral leg which provides a path for the zero-sequence current. Switches of the neutral leg are controlled to solve the problem of DC-link voltage oscillation. Firstly, the fundamental reason of the DC-link voltage oscillation under imbalance load is analyzed, and the selection guidance of DC-link capacitance for different imbalance loads is provided. A simulation model is introduced to verify the theoretical analysis. Based on the neutral leg and equivalent model of topology, a control method that is decoupled from others three phases is proposed to ensure the stability of output voltage and suppress voltage oscillation of DC-link capacitor. Meanwhile, this paper indicates the risks of system starting under V2H mode and introduces soft starting method by adjusting PWM dead time to enhance reliability of the system. Finally, the dual active bridge (DAB) is connected with 3-phase 4-wire inverter to deliver a 10kW V2H prototype. Imbalanced loads are simulated by switching resistance loads. The experimental results match the simulation results, which verifies the effectiveness of the proposed scheme.
付永升, 李静, 胡文婷, 雷鸣. 不平衡负载下车载三相四线双向充电器中线桥臂控制与软启动设计[J]. 电工技术学报, 2019, 34(24): 5176-5188.
Fu Yongsheng, Li Jing, Hu Wenting, Lei Ming. Neutral Leg Control and Soft-Start Design of 3-Phase 4-Wire on-Board Bidirectional Charger under Imbalance Load Condition. Transactions of China Electrotechnical Society, 2019, 34(24): 5176-5188.
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2019, Vol. 34 
