On-On and On-Off mode Phase-Shifted Full-Bridge TriMagiC Converter™ with Liqualloy™ Planar Transformers

This paper presents on-on and on-off mode high efficiency phase-shifted full-bridge TriMagiC Converter™ Isolated using Liqualloy™ planar transformer based on a low permeability, high saturation flux density and low loss material. The proposed converter is based on the phase-shifted full-bridge topology with series connected two transformers. In this topology, the transformer is not operated only as a transformer but also operated as an inductor. Therefore, output inductor is not necessary, which contributes to achieve better conversion efficiency and power density. To handle a high output current with low output voltage such as 3.3kW and realize down-sizing and high conversion efficiency, a planar type transformer using Liqualloy™ core is adapted. Since it has a high saturation flux density which is about two times larger than a typical Mn-Zn ferrite core, it does not need to open a gap in core to increase a saturation flux density which could be more suitable especially in this topology taking a high flux density due to its inductor operation. The proposed converter has the maximum output current of 244A, output voltage of 13.5V, maximum output power is 3.3kW with the switching frequency of 125kHz. In the experimental results, the peak efficiency is 96.8%, and the full load efficiency is reached at 93.7% respectively.