逆变器并联系统中谐波环流的抑制

逆变器中，死区等因素可造成输出电压波形的畸变，而瞬时值反馈调节对这种畸变有很好的校正作用。但在实验中发现，对于大功率逆变器，由于其滤波电感及并机电抗都很小，使得死区等因素可引起很大的谐波环流。瞬时值反馈控制虽然可获得良好的输出波形，但对于这种谐波环流的抑制能力却是非常有限的。本文为研究谐波环流的产生机理及瞬时值反馈控制对谐波环流的抑制作用，建立了基于谐波扰动的逆变器模型。研究表明，波形控制效果较好的瞬时值反馈控制技术，对谐波环流也有较好的抑制作用，而并机电抗将大大影响瞬时值反馈的谐波环流抑制能力。仿真与实验验证了上述结论。

The Restrain of the Harmonic Circulating Currents in Parallel Inverter Systems

In inverters, the distortion of the output sine voltage caused by factors like dead-times of power switches can be well compensated by the instantaneous voltage feedback regulators like PID controllers. However, in our experiments, we found that the dead-times could result in significant large circulating currents, and the instantaneous regulators had limited effect on restraining them, esp. in large power parallel systems where the filter reactors and output impedences must be small. In this paper, for analysis of the harmonic circulating currents, an inverter model that considered the bias of SPWM as a disturbence was established. The research of the restrain on harmonic circulating currents by the instantaneous regulators indicated that regulators that can achieve good waveforms could also lead to the better restraining of the harmonic circulating currents. The experiments and simulation validated the conclusion.