A 700kHz 800V/14V GaN-based DC-DC Converter with optimized Integrated Transformer for Electrical Vehicles

This paper proposes a high-step-down DC-DC converter for electric vehicles (EVs) with 800V battery system. The output of the input series half bridge (ISHB) converter is reconstructed to reduce the DC blocking capacitor in secondary. The maximum duty cycle of the proposed converter can be larger than 0.5, which allows the use of larger leakage inductance. This turns out to be a crucial advantage to achieve fully range ZVS in high switching frequency over 500kHz. The two transformers are integrated with partial cancellation, resulting in 20% of power loss and 32% of footprint reduction. A prototype of 1.2kW base on GaN devices achieves a power density of 10.2kW/1. Obtained maximum efficiency was up to 93%. Experiment results are provided to verify the proposed concepts.