The quasi-Z-source H-bridge grid-connected inverter(GCI)is well known as its no shoot-through problem and high efficiency of DC voltage,but the common-mode leakage current exists in the power frequency cycle.To solve the problems of quasi-Z-source H-bridge GCI,a new Z-Source photovoltaic grid-connected inverter(ZPGCI)with coupled cnductor coil topology is proposed.Also,a unipolar sinusoidal pulse width modulation(USPWM)strategy that can make the common-mode voltage constant is presented.Secondly,operating modes,common-mode leakage current and direct operating mode analysis shows that ZPGCI not only has the advantages of no shoot-through problem and high reliability,but also can eliminate the high-frequency common-mode leakage current of quasi-Z-source H-bridge GCI.At last,the correctness of the novel ZPGCI topology and theoretical analysis are verified by the comparison experiment of traditional quasi-Z-source H-bridge GCI and new ZPGCI circuit.
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