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PV Micro-Inverter Topology Using LLC Resonant Converter

Department of Electrical, Electronics and Information Engineering, Nagaoka University of Technology, Kamitomiokamachi, Nagaoka, Niigata 940-2137, Japan
Pony Electric Co., Ltd., Kitasaiwai, Yokohama, Kanagawa 220-0004, Japan
Author to whom correspondence should be addressed.
Energies 2019, 12(16), 3106;
Received: 11 July 2019 / Revised: 3 August 2019 / Accepted: 7 August 2019 / Published: 13 August 2019
(This article belongs to the Special Issue Advances in High-Efficiency LLC Resonant Converters)
PDF [2541 KB, uploaded 13 August 2019]


In this paper, a DC–single-phase AC power converter with an LLC resonant converter is presented for a photovoltaic (PV) micro-inverter application. This application requires the leakage current suppression capability. Therefore, an isolated power converter is usually combined for DC/AC systems. The LLC resonant converter is the one of the isolated power converter topologies, and it has good performance for conversion efficiency with easy control. On the other hand, a double-line frequency power ripple has to be compensated for in order to improve the performance of the maximum power point tracking (MPPT). Therefore, a bulky electrolytic capacitor is usually necessary for the power converter. However, the electrolytic capacitor may limit the lifetime of the micro-inverter. This paper introduces the PV micro-inverter with a LLC resonant converter. In addition, the active power decoupling circuit is applied in order to compensate the double-line frequency power ripple by the small capacitor in order to eliminate the electrolytic capacitor. Finally, the transformer design is considered in order to reduce the transformer losses. As a result, the conversion efficiency of the LLC converter is improved by 1% when the litz wire has many strands. View Full-Text
Keywords: PV micro-inverter; LLC converter; high switching frequency; transformer loss PV micro-inverter; LLC converter; high switching frequency; transformer loss

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Watanabe, H.; Itoh, J.-I.; Koike, N.; Nagai, S. PV Micro-Inverter Topology Using LLC Resonant Converter. Energies 2019, 12, 3106.

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