Magnetic Design of a 3-Phase SiC-Based PV Inverter With DC-Link Referenced Output Filter

Abstract

The use of Silicon carbide (SiC) devices represents an improvement in terms of size, weight and efficiency of power converters. However, SiC-based solutions present high dv/dt and di/dt on the switching events, increasing the common-mode noise injected into the grid. To reduce the common-mode noise, three-phase inverters with a DC-link referenced output filter are widely considered in photovoltaic (PV) inverters connected to the grid. However, if the filter is DC-link referenced the inductor ripple is larger, and this must be considered for the AC inductor filter design. This work shows, on a PV inverter, the impact of that DC-link referenced filter on the current ripple of the inductor, and the improvement achieved with the use of SiC devices, increasing the switching frequency. A comparison in terms of weight, size, losses and materials costs is presented for different core materials and configurations.

Keywords

• DC-AC
• silicon carbide
• grid-connected
• PV inverter
• AC filter inductors