三相四桥臂并联逆变器的零序电流建模与控制

摘要

针对三相四桥臂逆变器直接并联时的零序电流控制问题,通过建立直接并联三相四桥臂逆变器的桥臂平均模型,推导出零序电流的动态平均模型,揭示了系统中零序环流的形成机理.基于常用的载波正弦脉冲宽度调制(SPWM)方法,提出了基于第四桥臂电流闭环的直接并联三相四桥臂逆变器零序电流控制方法,从而抑制了两组直接并联逆变器第四桥臂中线间的零序环流.仿真和实验结果表明,所提出的控制方法能有效解决直接并联三相四桥臂电压源逆变器间的零序环流控制问题,可为微电网中大功率新能源发电并网逆变器的并机扩容提供技术保障.%Focusing on zero sequence current control in the directly paralleled three-phase four-leg inverter, the model of two directly paralleled inverter is established based on the phase-leg average theory, then the dynamic averaged model of zero sequence is deduced to reveal the generation mechanism of zero sequence circulation. The sinusoidal pulse width modulation (SPWM) in inverter is employed, a new zero sequence current control for directly paralleled three-phase four-leg inverter is then proposed based on the fourth-leg current closed loop, which is able to solve the zero sequence current control and suppress the zero sequence circulating current flowing through the four-legs between two directly paralleled inverters. The simulation and experiment indicate that the proposed control strategy effectively solves the zero sequence circulation in directly paralleled inverter, and provides technical support for high power new energy network expansion by the inverter in microgrid.