A Four-Phase Current-Fed Push-Pull DAB Converter for Wide-Voltage-Range Applications

In this article, a four-phase current-fed push-pull dual active bridge converter is proposed for applications requiring high power and a wide-voltage range. In addition to the conventional advantages of a small filter inductor, a small clamp capacitor, and low current stress in the primary switches due to the effect of four-phase interleaving, the proposed converter has a low total rms current of switches when operating at a wide-voltage range compared with the existing two- and three-phase converters. Also, the proposed converter was shown to be capable of the complete ZVS turn-on of all switches under a wide duty cycle range of 0.25-0.75 in both power-flow directions when small auxiliary inductors were added. A balanced four-phase transformer structure is proposed not only to cancel the dc-flux offset caused by the dc component of the primary winding current but also to reduce the core volume, footprint, and height of the transformer compared with the separated-core transformer. The experimental results from a 15-kW prototype are provided to validate the proposed concepts. The converter achieved a peak efficiency of 98% and maintained high efficiency when operated at a wide-voltage range.