GaN-Based Isolated Resonant Converter as a Backup Power Supply in Automotive Subnets

This article presents the analysis, design, and implementation of a 2 MHz, 12 V, 600 mA, GaN-based active-clamped isolated SEPIC converter (ACISC) supporting full zero-voltage switching (ZVS) throughout the 9-18 V automotive range, and intended to provide isolation and power interface between the 12 V battery and the low-power subnet. Designed for resonant discontinuous conduction mode (DCM) operation and leveraging the high switching frequency enabled by Gallium Nitride (GaN) devices, the selected topology leads to a reduction in total magnetic size and footprint, while maintaining a high efficiency profile. Both the theoretical models specifically developed for full ZVS resonant DCM operation, as well as the design and implementation of the transformer, are discussed. The analysis was verified through simulations and experimental measurements taken on a 7.2 W GaN-based prototype employing a planar transformer. Performance comparison with both a 7.2 W GaN-based active-clamped isolated flyback converter (ACIFC) and a commercial flyback converter is also included.