A Fully Soft Switched Converter for Ultracapacitors Interface Circuit

Ultracapacitors are used as auxiliary elements beside batteries in energy storage systems. In such a configuration a bidirectional, high efficiency converter is needed as an interface between ultracapacitors and batteries. This paper presents a ZVT buck and boost converter for the ultracapacitors interface. All of the switches in the proposed converter are soft switched and thus high efficiency is achieved. The converter operational modes are analyzed and its performance is justified using a 200 watt laboratory prototype.