High Efficiency Dual-Mode Current Modulation Method for Low-Power DC/AC Inverters

Boundary conduction mode (BCM) zero voltage switching (ZVS) current control is a promising soft switching method for microinverter applications. In this letter, different BCM ZVS current control modulation schemes are compared based on power losses breakdown, switching frequency range, and current quality. Compared to continuous conduction mode current control, BCM ZVS control decreases MOSFET switching losses and filter inductor conduction losses but increases MOSFET conduction losses and inductor core losses. Based on the loss analysis, a dual-mode current modulation method combining ZVS and zero current switching schemes is proposed to improve the efficiency of the microinverter. The experimental results show that by using this proposed current modulation scheme, higher efficiency of 0.5% can be achieved with no additional cost for a 400-W three-phase microinverter.