A High-Frequency-Link Split-Phase Voltage-Source Microinverter Based on Buck-Boost AC Chopper for High Efficiency and Low Voltage Stress

This article proposes a novel single-stage high-frequency-link split-phase microinverter that utilizes dual buck-boost ac choppers to form a secondary-side cycloconverter. This design achieves high voltage gain and a wide voltage regulation range, allowing for a reduced turns ratio in the high-frequency transformer (HFT). Consequently, voltage stress on the secondary-side switches is minimized, and associated losses in both the switches and HFT are reduced. An advanced modulation strategy is developed to enable soft-switching for all switches while effectively suppressing voltage spikes, without the need for additional clamping circuits. The microinverter supports split-phase output while maintaining voltage-source-inverter characteristics, making it suitable for both grid-connected and islanded operations. An accompanying control strategy ensures robust performance across both modes. Experimental results validate the effectiveness of the proposed topology, with a 600-W/50-Hz prototype achieving a peak efficiency of 97.12%.