An Improved Dual-Input Microinverter With Active Power Decoupling and Power Balancing

To address the technical challenges, such as leakage current, power fluctuation, and power balancing faced by single-phase nonisolated dual-input microinverters (MIs) in photovoltaic (PV) applications, a dual-input common-ground MI using power decoupling and power balancing capabilities is proposed in this article. In the improved microinverter (IMI), a common-ground structure is adopted to eliminate common-mode leakage current without any additional control burden. The proposed IMI uses only five switches and can independently process the power of two PV panels while ensuring the performance of the output side. To mitigate the issue of power imbalance between the two input sources in practical scenarios, an active power balancing strategy is developed. In addition, power decoupling between the two input sources and the AC side is inherent, so short-life, high-capacity electrolytic capacitors can be replaced with film capacitors. A 400 W experimental prototype has been built in the laboratory to verify the performance and feasibility of the proposed IMI and its control strategy.

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