A COMPARISON OF RESONANT AND NON-RESONANT DUAL ACTIVE BRIDGE TOPOLOGIES FOR SINGLE PHASE MICROINVERTERS

Abstract

In the commonly adopted non-resonant version of the dual active bridge-based DC-AC microinverter topology, the half-bridge (HB) capacitors are large to ensure an inductive tank circuit. This thesis explores performance implications of the resonant version of the circuit with reduced HB capacitances, and compares it with the non-resonant version. Modeling through multiple harmonic frequency domain analysis was leveraged to conduct design optimization of the impedance network parameters with varying resonant frequencies. A comparison between resonant and non-resonant designs was facilitated by developing two figures of merit relating to converter losses namely conduction loss factor (CLF) and switching loss factor (SLF). It was found that the CLF in resonant designs can be reduced compared to non-resonant designs, while both cases support near minimization of SLF, hence the efficiency can be slightly improved with resonant designs. More importantly, the reduction in the capacitance value enables reduced volumetric contributions, enhancing achievable power density.