Dual Optimization of an H-Bridge SPWM Microinverter by an Optimal Switching Frequency Tracking Technique

The switching frequency is among many design parameters of grid-tied single-phase H-bridge sinusoidal pulsewidth modulation (SPWM) microinverters. The selection of the switching frequency is a tradeoff between improving the power quality by reducing the total harmonic distortion (THD) and improving the efficiency by reducing the switching loss. This paper proposes two algorithms to optimize both the power quality and the efficiency of the microinverter by using a frequency tracking technique that requires no hardware modification. The first algorithm tracks the optimal switching frequency for maximum efficiency at a given THD value, while the second maximizes the power quality of the H-bridge micro-inverter by tracking the switching frequency that corresponds to the minimum THD. Experimental verification followed by results evaluation are presented.