A 32 kW Power-Dense Six-Phase Dual-Interleaved DC-DC Buck-Boost Converter with Three Interphase Transformer

This article presents a power-dense, six-phase dual-interleaved DC-DC Buck-Boost converter for electric/hybrid vehicle applications. This converter uses six hard-switched arms at 75 kHz, three dual-interleaved interphase transformers together with three common inductors and two filter capacitors at the input and output. The steady-state current ripple frequency of the common inductors is twice the switching frequency due to the dual interleaving in the interphase transformers. The resultant ripple current frequency of the input and output filters is six times the switching frequency; size and weight reduction of the passive components are obtained due to this frequency increase. The design and construction details of a 32 kW, 315-385 V supply, SiC-based prototype are presented along with experimental investigation. The prototype converter was successfully operated up to full load with a 350 V output, being the phase currents relatively balanced in the continuous conduction mode without a closed-loop control system. The prototype efficiency is 98 % at full load, being the gravimetric power density 7.56 kW/kg.