Study of WBG Switches Benefits on Asymmetrical Half-bridge Flyback Converter

Abstract:
Recent market trends are shaping the direction of power adaptors development. On the one hand, USB-PD standard that allows the reuse of power adaptors for multiple devices, thus reducing the electronic waste generated; on the other hand, fast battery charging features for mobile devices bring the need for higher adaptor power levels, resulting in bigger adaptor size. To reduce the size of the adaptor, a recent market trend drives the development of high-power density adaptors. In this paper, an USB-PD adaptor based on the asymmetrical Half-Bridge (AHB) flyback converter using wide band gap (WBG) devices will be presented. The behavior and advantages of WBG devices will be analyzed and compared to traditional Silicon switches. The theoretical analysis will be completed with experimental results of a 65W adaptor prototype using GaN devices, achieving with a peak efficiency over 95.5% and a minimum efficiency of 93.4% at full load over the input voltage range while reaching and a power density of 1.92 w/cm³ (31.5 w/inch³) uncased.