Low voltage single fuel cell interface by Push-Pull converter: a case of study

Fuel cells (FCs) are typically low-voltage sources, they are connected in stack structures to increase the operating rate voltage. An efficient DC-DC converter is needed as interface between FCs source and a constant dc bus. In this paper a different approach is proposed. Single cells are individually considered in a connection with an suitable DC-DC converter to provide the overall stack voltage as a sum of the each power converter output voltages. DC-DC Push-Pull power converter that manages a single module fuel cell has been investigated. The proposed solution allows to reduce the mismatching of FCs in a stack arrangement and possible damage of a single or groups of FCs module. Low input voltage (0.5-1V) is the most critical parameter of the converter design. Simulation results are presented by using accurate models of the devices used for the prototype realization in order to investigate several operative conditions leading the simulations results as close to reality. Finally the experimental tests on the circuit prototype realized are performed with several transformer cores selections with different magnetic permeability value in order to individuate the better solution for the Push-Pull High Frequency (HF) transformer design.