Current-fed full bridge converter for fuel cell systems

This paper deals with a single phase current- fed full bridge converter with high voltage gain for fuel cell applications. The clamping circuit is implemented by an auxiliary buck converter. An analytical investigation is given, describing the operating behaviour of the converter completely. This includes a distinction of the three operating modes: continuous mode, discontinuous mode and buck mode. With the results, the impact of the input inductor choke, the transformer´s winding ratio and its leakage inductance, the switching frequency and the output current on the voltage gain is emphasised. The theoretical limit of the transferable power is identified and considerations for an optimised converter design are given. To approve the analytical results, simulations are done and compared to the calculations. A 1.2 kW prototype was built and experimental results are given in this paper.