Method and apparatus for fuel cell protection

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells connected in series and coupled to a load;
• monitoring a voltage of each fuel cell;
• comparing each monitored voltage to a preset level;
• switching the load off in response to the voltage falling below the preset level;
• and
• switching the load on in response to the voltage rising above the preset level.

A fuel cell system, comprising:

• a stack of fuel cells connected in series;
• a controller coupled to the stack, the controller providing individual cell voltage monitoring capability, a reference voltage, and comparator functionality to generate a control signal indicating that one or more individual cell voltages has fallen above or below a preset level;
• a DC/DC converter for sourcing power from the stack and providing a converted output voltage;
• a load switch for receiving the control signal and the converted output voltage;
• and
• a main load coupled to the load switch, the load switch responsive to the control signal for switching in and out the main load.

A fuel cell system, comprising:

• a plurality of fuel cells connected in series and coupled to a load;
• a controller for determining individual fuel cell voltage level and providing a control signal based on the individual fuel cell voltage levels, the control signal indicating whether fuel cell operation is in or out of negative dP/dI region;
• and
• a load switch coupled between the plurality of fuel cells and the main load, the load switch disconnecting the load from the fuel cells in response to the control signal to prevent operation of the fuel cell system in the negative dP/dI region.

A fuel cell system, including:

• a stack of fuel cells coupled in series;
• a controller coupled to the stack;
• a load operatively coupled to the fuel cells;
• and
• the controller monitoring each fuel cell voltage, comparing each fuel cell voltage to a reference voltage, and generating a control signal for disconnecting and reconnecting the main load.

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells connected in series and coupled to a load;
• monitoring the voltage of more than one cell within the stack;
• comparing the monitored voltage to a preset level;
• switching the load off in response to the voltage falling below the preset level;
• and
• switching the load on in response to the voltage rising above the preset level.

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells connected in series and coupled to a load;
• monitoring the voltage of the stack;
• tracking power drawn by the load;
• determining slope of the power versus voltage;
• switching the load off if the slope is zero or positive;
• and
• switching the load on in response to the slope being negative.

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells connected in series and coupled to a load;
• monitoring the current of the stack;
• tracking power drawn by the load;
• determining a slope of the power versus current;
• switching the load off, in response to the slope being zero or negative;
• and
• switching the load on, in response to the slope being positive.

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells coupled in parallel and coupled to a load;
• monitoring a current of each fuel cell;
• comparing each monitored current to a preset level;
• switching the load off in response to the current rising above the preset level;
• and
• switching the load on in response to the current falling below the preset level.

A fuel cell system, including:

• a stack of fuel cells;
• a controller coupled to the stack;
• a load operatively coupled to the fuel cells;
• and
• the controller monitoring a fuel cell parameter, comparing the fuel cell parameter to a preset level, and generating a control signal for disconnecting and reconnecting the load depending on the fuel cell parameter.

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells with a load operatively coupled thereto;
• monitoring at least one parameter of one or more of the fuel cells;
• comparing the parameter to a preset parameter level;
• and
• disconnecting or reconnecting the load in response to the fuel cell parameter.

A method of protecting a fuel cell system, comprising:

• providing a stack of fuel cells operatively coupled to a load;
• monitoring a parameter of the stack;
• tracking power drawn by the load;
• determining slope of the power versus parameter;
• switching the load off on or off in response to the slope having a predetermined characteristic.