Coat Circuits for DC-DC Converters to Improve Voltage Conversion Ratio

The voltage conversion ratio of basic dc/dc converters is limited due to the influence of parasitic elements of circuits and components. In this article, a family of passive circuits termed as "coat circuits" are proposed for conventional dc/dc converters. Not only voltage step-up capacity can be improved but also the voltage stress of components can be decreased by adding coat circuits to basic dc/dc converters. Moreover, no additional active switches are needed in the coat circuits, that means the control and driver circuits of the converters are not changed. The Cuk converter with the coat circuit has been analyzed as an example, and a 200 W experimental prototype has been built to verify the validity of the theoretical analysis.