557Dynamic Simulation and Fuel Cell Control System
are held steady. Fuel cells for transportation denitely require controls since
they will experience widely varying changes in power demand just like
internal combustion engines in present vehicles. A fuel cell stack has to be
operated properly to get good power efciency, reliability, and smooth oper-
ation; hence, a control system is required during steady-state operation and
current level changes. Controls can be used to regulate the ideal amounts of
reactants, cell temperature, inlet humidity, and output power, for example.
Many different control congurations can be used to accomplish these goals.
In a PEM fuel cell, three key control systems are required for air and fuel
delivery, water ...