The Electrical Dynamic Response Study of PEMFC as a Backup Power Supply

The use of fuel cell technology as a backup power source for the uninterruptible power supply (UPS) requires quick response to sudden load change. However, slow dynamic behavior of a PEM fuel cell, compared to the typical power conditioner and load, limits the fuel cell rapid transient response to load change. To increase the fuel cell response to load change, the energy storage such as battery, micro turbine, photovoltaic and super-capacitors are conventionally installed in the system thus increasing in its size and cost. In this work, the PEM fuel cell transient behaviors in the cool-start, hot-start and load change were investigated by using in-house running control software and high precise oscilloscope. The effects of fuel cell structure (area of flow field, cell number and materials used in MEA) and operation conditions (pressure, temperature etc.) were also studied. The electrical response results from experimental curves indicate that the transient behavior of fuel cell stack is highly impacted by the fuel cell structure, operating conditions and the strategy of gas input into the fuel cell. The better understanding of the electrical response of PEM fuel cell would be helpful to the design of a fuel cell and its system with high efficiency and compact structure.