Miniaturization of the boost-up type active buffer circuit in a single-phase inverter

This paper discusses miniaturization of a single-phase grid connected inverter, which has power decoupling function for PV. The power ripple of twice grid frequency is compensated in the proposed circuit with the small capacitor (50 μF) at 200 W. However, the buffer inductor in the proposed circuit becomes large because the buffer inductor current is fluctuated at twice grid frequency by power ripple compensation, and the switching ripple is large at the peak current. In this paper, in order to reduce the size of the buffer inductor, the buffer inductance is optimized in terms of the volume and efficiency according to the switching frequency. As an experimental result, it is confirmed that the input current ripple is reduced by 90 % in the proposed circuit, and the output current THD is 3.5 %. On the other hand, the buffer inductance is reduced by 73 % at 64 kHz of the switching frequency. In addition, the volume of the proposed circuit can be reduced by 37% in compared to the conventional circuit. Finally, from the evaluation of the power density using the Pareto front curve, the proposed circuit can design the high power density in compared to the conventional circuit.