A novel voltage regulation strategy for micro-inverters with a low-capacitance dc-link

The micro-inverter has become more and more attractive due to the inherent advantages compared to traditional photovoltaic inverters. In order to prolong the lifetime of micro-inverters, the film capacitor is usually used instead of the electrolytic capacitor in the dc-link. However, due to the small capacitance of the film capacitor, the voltage regulation of the dc-link capacitor is much more difficult than the traditional inverters with electrolytic capacitors. In this paper, a new dc-link voltage regulation strategy for the micro-inverter is proposed. Based on the hysteresis methodology, two kinds of control scheme is adopted, which can keep the dc-link voltage stable both in steady state and dynamic state, and export smooth current with low oscillation to the grid. Simulation results verify the validity of the theoretical analysis and the feasibility of the strategy.