双环控制逆变器采用虚拟阻抗的并联控制策略

Control Strategy Using Virtual Impedance for Parallel-connected Inverters With Double-feedback-loop Control

针对各模块采用双闭环控制的逆变器并联系统,分析了系统环流阻抗和输出特性,在此基础上,提出了一种在瞬时平均电流控制环中引入虚拟阻抗的均流控制策略。通过配置虚拟阻抗将逆变器环流阻抗调节为纯阻性,从而获得各逆变器模块环流与指令电压间的比例调节关系。分析表明,虚拟阻抗的引入不会改变并联系统的输出特性,与传统的瞬时平均电流控制相比,基于虚拟阻抗的均流控制策略具有更高的均流精度,且在保证均流效果的同时能避免调制信号饱和。最后,针对并联系统接入线性和非线性负载的情况,通过仿真和实验验证了所提方法的有效性。

Based on the analyses of circulating current impedance and the output characteristic of the parallel-connected inverters with double-feedback-loop control,a current-sharing control strategy is proposed,where the virtual impedance is introduced in the instantaneous average current-sharing control loop.By configuring the virtual impedance,the circulating current impedance of each inverter module can be set as pure resistive,so that the proportional regulation relationship between the circulating current and the reference voltage of each module is obtained.Analyses show that the introduced virtual impedances do not influence the output characteristic of the parallel system.Compared with the traditional instantaneous average current-sharing control,the proposed strategy can obtain better current-sharing capability,and can avoid the saturation of the modulation signal.When the parallel system is connected with linear and nonlinear loads,simulation and experimental results prove to validate the effectiveness of the proposed method.