The influence of power electronic dynamics on PEM fuel cell-system

Fuel cells are very promising for use in stationary and mobile electricity generation, for example traction and portable power. The paper describes the influence of switching power electronics on the efficiency and lifetime of fuel cells. The main topic is the dynamic operation of a fuel cell and the influence of the gas supply. Measurements were done to prove the linear behaviour of the fuel cell in a certain frequency range with high AC current components. A simple way is described to calculate the additional losses caused by a 100 Hz modulated power demand or the current ripple of a power electronic device. Further the dynamics of the fuel cell with different gas supplies are demonstrated in general and the influence of dynamic operation with sufficient and not-sufficient gas supply on the lifetime are presented. The paper provides fundamental knowledge for the design of power electronics in order to optimise the efficiency of fuel cells with minimum costs.