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

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.

Automated summary

The use of SiC devices in power converters improves size, weight, and efficiency. However, SiC-based solutions increase common-mode noise injected into the grid due to high dv/dt and di/dt during switching events. To reduce the noise, three-phase inverters with a DC-link referenced output filter are commonly used in PV inverters. This study examines the impact of the DC-link referenced filter on inductor current ripple and the benefits of using SiC devices to increase switching frequency.