Analysis and design of a new ZCS-PWM full-bridge fuel cell converter

Abstract

PWM full-bridge dc-dc boost converters are used in applications where the output voltage is considerably higher than the input voltage. Zero-current switching (ZCS) is typically implemented in these converters. Previous proposed ZCS-PWM full-bridge boost converters, however, have a number of drawbacks that are related to the circulating current that must be generated to divert current away from the main full-bridge switches so that they can be turned off with ZCS. This circulating current is a source of significant converter losses and peak switches stresses. In order to reduce these problems, a new ZCS-PWM dc-dc full-bridge boost converter is proposed in the paper. In the paper, the operation of the proposed converter is explained, and a detailed mathematical analysis of its steadystate operation is performed. A procedure for the design of the converter is given and demonstrated with an example. The feasibility of the converter is confirmed with results obtained from an experimental prototype.Index Terms--Dc-dc power conversion, switch-mode power supply, pulsewidth modulated (PWM) converters, soft switching, zero-current switching (ZCS).