A Single-Stage High-Frequency-Link Split-Phase Microinverter for Both Grid-Tied and Islanded Operation
Xuewen Li, Jia Liu, F. Ji, Xueqian Cao, Yue Wang, Jinjun Liu
Abstract
High-frequency-link (HFL) inverters have drawn a lot of attention, owing to their high transformer utilization factor, bidirectional energy transfer, and easy implementation of soft switching. Therefore, HFL-based topologies might be a promising solution for the next-generation 600-W class microinverter. However, the utilization of HFL structures in split-phase systems, and the ability to operate in both grid-tied and islanded modes are rarely studied. Therefore, a novel single-stage high-frequency-link voltage-source microinverter with a split-phase structure is proposed in this paper. The proposed microinverter can provide a split-phase output voltage to match the single-phase three-wire distribution system. The two-phase output voltages can be balanced naturally without dedicated control. Meanwhile, all switches achieve soft-switching by the proposed secondary-side modulation (SSM) strategy. Owing to the voltage-source-inverter (VSI) feature, the proposed microinverter can be used in both grid-connected and islanded applications, of which the control strategy is also proposed in this paper. Finally, its dual-mode operation is validated via a 600-W/50-Hz prototype, with a peak efficiency of 94.6%.