Two-Stage Transformerless Dual-Buck PV Grid-tied Inverters with Improved Efficiency

In this paper, a two-stage transformerless dual-buck PV grid-tied inverter is proposed. Its characteristics are that part of the PV panel power can be supplied to the utility grid directly through this power flow path, without being transferred by the front-end Boost converter. Therefore, the power conversion stage is relatively small and power loss is small; because its frequency variation of common-mode(CM) voltage is low, it features with low leakage current; part of the power switches and power diodes are connected in series, which reduces the voltage stress of the power switches and power diodes. The operation principle is analyzed in detail, a prototype is built and experimental results with one kind of modulation strategy are provided to verify the effectiveness and advantages of the proposed inverter.