HIGH EFFICIENCY INTERLEAVED ACTIVE CLAMPED DC-DC CONVERTER WITH FUEL CELL FOR HIGH VOLTAGE APPLICATIONS

Abstract

This seminar report entitled ”Interleaved Active Clamped Dc-Dc Converter with Fuel Cell for High Voltage Applications” presents analysis and design of interleaved zero voltage switching (ZVS) active-clamped current-fed full-bridge isolated dc/dc converter for fuel cell applications. The designed converter maintains ZVS of all switches from full load down to very light load condition over wide input voltage variation. Detailed operation, analysis, design and simulation results for the pro- posed design are presented. As the fuel cell output is very low we are in need of a step up dc-dc converter. Here a current fed dc-dc converter is used. Two current fed dc-dc converters are interleaved by connecting their inputs in parallel and outputs in series. With this proposed methodology input current ripples in the fuel cell stacks can be reduced and a regulated output voltage ripples can be obtained. The addi- tional auxiliary active clamping circuit absorbs the turn-off voltage spike limiting the peak voltage across the devices allowing the selection and use of low-voltage devices with low on-state resistance. In addition, it also assists in achieving ZVS of semicon- ductor devices. The converter utilizes the energy stored in the transformer leakage inductance aided by its magnetizing inductance to maintain ZVS. ZVS range depends upon the design, in particular the ratio of leakage and magnetizing inductances of the transformer. Voltage doubler circuits will give double the output voltage than normal with smaller transformer turns ratio and flexibility.