Core-less multiphase converter with transformer coupling

A coupled multiphase converter where the coupling among the phases is done using core-less planar transformers is presented in this paper. Operating principle of the transformer-coupled converter has been presented previously in the literature and in this paper this concept is applied to develop a core-less converter. Two prototypes operating at high frequency (4 MHz), with low profile (3 mm - 4 mm) and 60 W of output power, with two different core-less transformers are presented. Main advantages of applying this concept at high frequency are size reduction and operation with core-less transformers. This topology can be considered as a dc-dc transformer and applications for this topology can be `dc-dc transformers' for two-stage power supply systems and voltage scaling power supplies.