Abstract: A variable capacity compressor that is operable in a normal mode and either an upward or downward rapid transient mode includes a compressor that compresses a fluid and a motor that drives the compressor. A controller powers the motor from a main power source when operating in the normal mode and powers the motor from a supplemental power source when operating in the upward rapid transient mode.

Abstract: An apparatus and method for operating a fuel cell power system utilizing a low voltage power source and system power to power an airmover. The fuel cell power system uses a low voltage power source to power the airmover during start-up and transitions to using system power to power the airmover as the fuel cell stack increases its voltage output. During a shutdown operation the fuel cell power system transitions from using system power to using the low voltage power source to power the airmover enabling a purging operation to be performed. A controller coordinates the operation of the airmover between using the low voltage power source and using electrical power produced by the fuel cell stack to power the airmover.