Energy efficiency enhancement in full-bridge PV inverters with advanced modulations

Abstract

Transformerless single-phase inverters are preferring in residential grid-connected PV systems when compared to galvanic-isolated ones (i.e., transformer-based inverters). In addition to the special leakage current issue, high efficiency, power quality and reactive power injection are of concern that should be considered in grid-connected applications. Nowadays, the fast development of wide-bandgap (WBG) devices brings new challenges to transformerless inverters, e.g., electromagnetic interference (EMI) issues, but efficiency can be improved. This paper first reviews the full-bridge PV inverters seen from the perspective of topology configuration. The oscillation during switching transitions is analyzed and compared in typical full-bridge inverters under a hybrid modulation method, which has a significant relationship with the EMI issue. Then, power loss distribution is discussed to reveal the thermal performance under the hybrid modulation scheme with reactive power injection. Simulations are carried out on the full-bridge prototype to validate the discussions of the hybrid modulation strategy.