Analysis and Optimization of Single-Phase T-Type BCM Microinverter

This paper presents a detailed power loss model for a single-phase T-type boundary conduction mode (BCM) microinverter. And an optimized modulation strategy is proposed based on the established power loss model. This method uses dynamic reverse boundary current for control, and additionally realizes a zero-current switching (ZCS) of a switch, which further reduces the converter loss and improves power density. At the same time, the problem of output current distortion at the mode switching point under the fixed reverse current modulation strategy is improved. In addition, there is no need to add any auxiliary components to realize the optimized modulation strategy, and it can be realized only with a digital controller. At different power levels, the loss of the converter under two modulation strategies is analyzed using the established loss model, and the superiority of the proposed modulation strategy is verified. At the same time, it is verified through simulation that ZCS and zero voltage switching (ZVS) can he realized simultaneously in a certain range, and the output current waveform quality is further improved.