Abstract：Under unbalanced conditions, the three-phase four-leg inverter parallel system not only can output balanced three-phase voltage waveforms, but also can expand the capacity of the system. Compared with the traditional three-leg inverter parallel system, the three-phase four-leg inverter parallel system need to control the positive, negative and zero sequence current, so the control of three-phase four-leg inverter parallel system is more complex. In this paper, the distribution of the sequence current in parallel operation of three-phase four-leg inverter is analyzed. In order to make the inverter output of positive, negative and zero sequence current to distribute according to the parallel inverter capacity. This paper puts forward a new control method that the positive sequence current uses a droop control, negative sequence current and the fourth leg current use virtual impedance method respectively control the positive sequence current, negative sequence current and zero sequence current distribution of the inverter output, and the front three leg and the fourth leg of the three-phase four-leg inverter control independently. Finally, the output voltage is balanced at the same time the output current and the output power of the parallel system are distributed according to the capacity of the parallel inverter under unbalanced conditions, and the circulation of the system is reduced. The correctness of the method is verified by simulation and experiment.
闫朝阳, 白鹤, 张喆, 李建霞. 不平衡工况下基于虚拟阻抗法的并联三相四桥臂逆变器的桥臂控制[J]. 电工技术学报, 2017, 32(23): 207-219.
Yan Zhaoyang, Bai He, Zhang Zhe, Li Jianxia. Leg Control of Parallel Three-Phase Four-Leg Inverter Based on Virtual Impedance Method under Unbalanced Conditions. Transactions of China Electrotechnical Society, 2017, 32(23): 207-219.
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2017, Vol. 32 
