Analysis of MHz 380V-12V DCX with Low FoM Device

1MHz isolated high efficiency high power density DC/DC converter is critical for future industrial applications. The GaN devices have a better performance for such high frequency than silicon device of high breakdown voltage due to their much lower parasitic capacitance. The modeling of the primary switches conduction losses is built in this paper. Based on the model the relation between the NFoM (Rdson.Cotr) of primary devices and conduction loss is revealed, thus the lower voltage devices with lower FoM is adopted to implemented the experimental verification. Since the equivalent NFoM is independent of the device count of series connection and is decided by single device, an input-series output-parallel structure prototype with multiple SRC DCX cells is implemented with low voltage MOSFETs. The 380V-12V prototype achieves a peak efficiency of 98.3% and a power density of 810W/inch
³
with multiple 60V MOSFETs.