Efficiency Improvement with Off-time Discrete Control for 1 MHz Operated Discontinuous Current Mode Grid-tied Inverter

This paper presents an efficiency improvement of an 1 MHz operated grid-tied inverter using GaN-HEMT devices based on a discontinuous current mode (DCM). The parasitic capacitance of the devices and printed circuit board (PCB) forms a resonant circuit with the filter inductor during the zero current period of the DCM. An off-time discrete control has been proposed to achieve an uniform turn-on and zero voltage switching (ZVS) by discretely adjusting the oscillation period. This paper investigates the efficiency improvement by the ZVS. Two PCBs with different layouts were considered and fabricated to analyze the effect of the parasitic capacitance. The effectiveness of the off-time discrete control was verified by experiments with two fabricated prototypes.