High-Efficiency Microinverter With Interleaved Switching and Asymmetrical Unipolar Modulation

This paper introduces a high-efficiency two-stage power microinverter. In the dc-dc stage, a three-phase interleaved inverse buck-type converter is adopted to regulate the dc-bus voltage and improve the input ripples. A band-stop filter and a PR controller are employed to eliminate the double-line frequency ripple. Furthermore, a highly reliable inverter combines an H-bridge topology and two low-frequency switches. Interleaved switching and asymmetrical unipolar modulation are used to improve conversion efficiency. The high and low switching frequency legs synchronization minimizes distortion on the output voltage waveform. Finally, all control algorithms are implemented in a TI DSP TMS320F28069 chip. A 2 kW prototype utilizing GaN devices has been developed and verified. The average efficiency of the overall system achieves 98%.