Single power-conversion DAB microinverter with safe commutation and high efficiency for PV power applications

Abstract

This paper presents a single power-conversion dual-active-bridge (DAB) microinverter with safe commutation and high efficiency for PV power applications. In DAB microinverters, the commutation problem is a crucial issue which must be solved in order to achieve a higher power capability. Owing to its novel circuit structure, the proposed microinverter can provide the commutation path in any switching case, so that it avoids the high voltage spikes from the commutation problem and provides high reliability. Moreover, the proposed microinverter has a circuit structure that is simpler and requires fewer auxiliary circuits compared to conventional DAB microinverters. In addition, the proposed microinverter achieves simple closed-loop current control and zero-voltage-switching turn-on of all switches owing to its control algorithm. Because these advantages are obtained with only a single power-conversion, the proposed microinverter has high efficiency and simple structure with high reliability. The operation principle and commutation issue of the proposed microinverter are theoretically analyzed in detail, and experimentally validated on a 400-W prototype.