This paper discusses the working principal and design of an all-GaN, PCB-winding based two-stage 1.8kW 400V – 48V battery-to-battery DC-DC converter for automotive applications. The first stage is a buck 2-phase interleaved converter with coupled inductors to provide good regulation. The second stage is an unregulated LLC converter with matrix transformer for high efficiency isolation and step down. The DC-DC converter can achieve 96.6% full-load efficiency at nominal condition (350V/44V) and a power density of 5kW/L. Moreover, some thermal management techniques have been presented to manage the active devices and PCB winding temperatures for the on-board converter.
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