Method for limiting the output voltage of a PEM fuel cell system

摘要

The method for limiting the output voltage of a PEM fuel cell system operating in, or near, zero load conditions, in such a way as to minimize degradation of performance over time, comprises:
supplying a hydrogen stream to the anode of the fuel cell;supplying an oxygen stream to the cathode of the fuel cell;monitoring an output voltage of the fuel cell;monitoring a hydrogen pressure in the fuel cell;monitoring an oxygen pressure in the fuel cell;limiting the hydrogen stream and the oxygen stream while actuating controllable recirculating pumps for the hydrogen and the oxygen in such a way as to bring and maintain the hydrogen and oxygen pressures below 1 barabsolute while maintaining the hydrogen pressure between 70 and 130% of the oxygen pressure, so that the output voltage remains below 0.90 volts.

主权项

1. A method for limiting the output voltage of a PEM fuel cell system operating in an idling state in zero connected load conditions in such a way as to minimize degradation of performance over time, the PEM fuel cell system comprising an anode, a cathode, a controllable hydrogen recirculating pump, and a controllable oxygen recirculating pump, wherein the method comprises:
(a) operating the PEM fuel cell system in zero connected load conditions; (b) supplying a stream of pure hydrogen to the anode of said fuel cell; (c) supplying an stream of pure oxygen to the cathode of said fuel cell; (d) monitoring an output voltage of the fuel cell; (e) monitoring a hydrogen pressure in the fuel cell; (f) monitoring an oxygen pressure in the fuel cell; (g) limiting the stream of hydrogen and the stream of oxygen and actuating the hydrogen and oxygen recirculating pumps in such a way as to bring and maintain the hydrogen and oxygen pressures below 0.7 barabsolute while maintaining said hydrogen pressure between 70 and 130% of said oxygen pressure, so that the output voltage remains between 0.65 and 0.90 volts, and the idling state is achieved.