DC/DC converter topology selection for low frequency ripple reduction in PEM fuel cell applications

Fuel Cell systems require power conditioning to interface them to loads or the utility grid. In single phase applications normal operation of the power conditioning converter introduces a significant second harmonic current ripple that reduces the power availability of the stack up to 20%. A similar effect can be observed in three phase applications operating under unbalanced loads. To mitigate this issue it is required to reduce or eliminate the low frequency current components circulating through the fuel cell, which can be done by additional filtering or proper selection of the DC/DC converter stage in the power conditioner. In this paper theoretical analysis is carried out in order to identify the DC/DC converter family that is better suited to reduce the unwanted current components in the stack. As a result it is shown that current source converter topologies appear as a convenient choice to meet the aforementioned goal.