A Novel Power Decoupling Circuit in Paralleled with AC Side in Photovoltaic Micro-Inverter

A power decoupling circuit for photovoltaic micro-inverter is studied. The power decoupling circuit is composed of basic buck-boost circuit and is connected in parallel with a voltage source inverter controlled by hysteresis strategy. Since the power should be decoupled in each switching cycle, power decoupling circuit uses peak current control method. In this way, voltage ripple on decoupling capacitor is increasing and the capacitance of it is decreasing. Therefore, a micro- inverter without electrolytic capacitor, which has longtime, can be realized. Four operating modes of the power decoupling circuit are analyzed in this paper. The values of decoupling inductance and decoupling capacitor are calculated. The proposed micro-inverter and its control strategy are simulated by Matlab/Simulink. The experimental results show that the power decoupling circuit of proposed micro-inverter is effective and can reduce the capacitance of the decoupling capacitor to several tens μF. In this way, the lifetime of the proposed micro-inverter could match that of the PV panel.