Patent ID: 8277989

Claim:
A fuel cell system comprising: a fuel cell stack including a cathode input receiving a charge airflow; a compressor generating the airflow provided to the cathode input of the fuel cell stack; a motor for driving the compressor; a mass flow meter receiving the airflow sent to the compressor, said mass flow meter generating an airflow signal indicative of the airflow through the compressor; a pressure sensor measuring the pressure of the cathode air at an output of the compressor, said pressure sensor generating a pressure signal; an air filter receiving the air sent to the compressor and filtering the air; and a controller configured to be responsive to the airflow signal from the mass flow meter and the pressure signal from the pressure sensor, said controller providing a signal to the motor to control the speed of the compressor, said controller digitally storing a compressor map of the operation of the compressor, said controller configured to use the pressure signal, the airflow signal, the speed of the compressor and the compressor map to determine the inlet pressure of the compressor so as to determine the condition of the air filter and whether the air filter should be replaced.