Phase skipping control to improve light load efficiency of three phase micro-inverters

Incident solar power on a PV panel is highly variable due its dependence on weather, time of the day and shading which forces the micro-inverter to operate at light loads for a significant period of its operation time. Poor light load efficiency of power converters further reduces the effective power available. This paper proposes a control technique - Phase Skipping Control, to improve light load efficiency of DC-AC stage of Grid Tied-Three Phase Micro-Inverters. This control technique is independent of the underlying topology; however, to establish its proof of concept, Phase Skipping Control, is implemented on a 400W Three Phase Half Bridge PWM Inverter. Improvement in light load efficiency with Phase Skipping Control is calculated theoretically using a proposed loss model for Half Bridge PWM Inverter. Furthermore, a prototype for 400W Three Phase Half Bridge PWM Inverter is developed for experimental verification of light load efficiency improvement using Phase Skipping Control. Experimental results shows 5.43% increase in efficiency at 10% load and 0.46% increase in CEC efficiency of the Three Phase Half Bridge PWM Inverter.