PV Micro-Inverter Topology Using LLC Resonant Converter

Hiroki Watanabe, Jun-ichi Itoh, Naoki Koike and Shinichiro Nagai
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Hiroki Watanabe: Department of Electrical, Electronics and Information Engineering, Nagaoka University of Technology, Kamitomiokamachi, Nagaoka, Niigata 940-2137, Japan
Jun-ichi Itoh: Department of Electrical, Electronics and Information Engineering, Nagaoka University of Technology, Kamitomiokamachi, Nagaoka, Niigata 940-2137, Japan
Naoki Koike: Pony Electric Co., Ltd., Kitasaiwai, Yokohama, Kanagawa 220-0004, Japan
Shinichiro Nagai: Pony Electric Co., Ltd., Kitasaiwai, Yokohama, Kanagawa 220-0004, Japan

Energies, 2019, vol. 12, issue 16, 1-11

Abstract: 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.

Keywords: PV micro-inverter; LLC converter; high switching frequency; transformer loss (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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