Power Loss Analysis of a Single-Phase Differential Buck Inverter with Power Decoupling Utilizing Energy Stored in Output Capacitors

With solar energy being one of the most essential sources for general energy transition towards renewable sources, the need for light and efficient photovoltaic (PV) inverters becomes crucial. A PV micro-inverter, having the advantage of omitted dc-wiring and modular flexibility becomes attractive. However, single-phase applications cause the drawback of bulky dc-link capacitors required to compensate doubled frequent power fluctuation on the solar module. This paper presents an active power decoupling method without the need of additional switches by modulating a common-mode (cm)-voltage on the filter capacitors of a differential buck inverter. Based on literature, a stability analysis and simulation is performed. The objective of this paper is to investigate the effect of different variations of dc-link voltage and filter capacitor size on decoupling performance and semiconductor losses, aiming for an optimal inverter design.