基于阻抗匹配模式的并联逆变器均流方法

Current sharing method for parallel inverters based on impedance matching mode

针对逆变器并联系统的动态均流问题,提出了阻抗匹配模式的逆变器并联控制方案。依据电路等效理论,将开环控制的逆变器等效为给定电压源与虚拟阻抗串联的电路形式,并给出了阻抗参数的辨识方法。以逆变器的等效电路作为被控对象模型,推导出可改变逆变器输出虚拟阻抗的控制方法。给出了并联逆变器间的虚拟阻抗匹配关系。所设计的逆变器除需共享电压给定基准正弦信号外,完全自主均流,控制方法简单。采用两台容量为1 kVA、空载输出电压为220 V的逆变器并联进行了仿真和实验研究。仿真与实验结果显示:两台逆变器输出电流之差峰值小于0.1 A;在负载阶跃变化中,无过渡过程。

To solve the dynamic current sharing problem of inverter parallel system,a parallel inverter control scheme with impedance matching mode was proposed.According to the equivalent theory of circuit,the inverter of open-loop control was equivalent to the constant voltage source and the virtual impedance in series form,the impedance parameters identification method was given.The equivalent circuit of the inverter was treated as the controlled plant and the control method was derived to change the output virtual impedance of the inverter.Virtual impedance matching condition between the parallel inverters was given.Besides the given sinusoidal voltage signal shared by the invert in the proposal,the current sharing independently was realized.The control methods are simple and easy to be applied.Simulation and experimental studies have been carried out on two parallel connected inverters which capacities are 1 kVA and no-load output voltages are 220 V.Simulation and experimental results show that the difference of the two inverter output current peak is less than 0.1 A and there is no transition process under load step change.