A Simple Switching Ripples Reduction Method for Split DC Capacitor Three-Phase Four-Wire Grid-Tied Inverters

In this paper, it is unveiled that even for a traditional split dc capacitor three-phase four-wire inverter, there are opportunities to significantly reduce the neutral and phase current high frequency ripples with only slight modification of modulation approach and output filter configuration. Firstly, by using the interleaved carriers for three phase inverter legs, the switching ripples of inverter neutral output current is effectively mitigated. To mitigate the switching ripples of phase line current and reduce the inductance of the whole system, an LCLCL filter that has an LC series resonance path at the switching frequency is adopted to absorb phase line current ripples. With the abovementioned modifications, the phase line current and neutral output current switching harmonics are mitigated simultaneously, even with relatively small filter components.