Method and apparatus for operating a fuel cell system

• US 6,519,510 B1
• Filed: 05/26/2000
• Issued: 02/11/2003
• Est. Priority Date: 07/28/1998
• Status: Expired due to Term

• Current Assignee: Audi AG (Volkswagen AG)
• Original Assignee: UTC Fuel Cells, LLC (Doosan Corporation)
• Inventors: Margiott, Paul R., Kabir, Zakiul, Callaghan, Vincent M.
• Primary Examiner(s): Black; Thomas
• Assistant Examiner(s): GAIN, EDWARD F
• Application Number:
  US09/525,728
• Time in Patent Office: 991 Days
• Field of Search: 700/275,286,292,293,297,295,299
• US Class Current: 700/299
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/0258 characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/04029 Heat exchange using liquids
• CPC Class Codes: H01M 8/04223 during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04228 during shut-down
• CPC Class Codes: H01M 8/04231 Purging of the reactants
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04303 applied during shut-down
• CPC Class Codes: H01M 8/04358 of the coolant
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04731 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/086 Phosphoric acid fuel cells [PAFC]
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

Method and apparatus for changing the state of operation of a fuel cell, such as starting the fuel cell up or shutting the fuel cell down, are disclosed. An idle load is applied to the fuel cell when the cell temperature is between about normal operating temperature and a transition temperature, and fuel and oxidizer are supplied to the fuel cell commensurate with the power delivered to the idle load. Below the transition temperature, purging/passivation procedures known in the art can be followed, and an open or dummy load applied to the fuel cell. At normal operating temperature or above a service load is applied to the fuel cell.

Claims

1. A fuel cell system, comprising:

at least one fuel cell;

a cooling system for circulating a cooling fluid for controlling the temperature of the fuel cell;

a temperature sensor for monitoring the temperature of one of the cooling system coolant and the fuel cell for providing an electrical signal responsive to said temperature;

a load control means for selectively applying one of an idle load and a service load to the fuel cell;

a processor for controlling the transition of the fuel cell between a normal state of operation at a normal operating temperature and under the service load and a second state at a second temperature less than normal operating temperature, the processing including;

at least one memory element storing a program for execution by said processor, the program including;

first means responsive to the electrical signal for controlling said load control means to apply the idle load to the fuel cell when the temperature of the fuel cell is approximately the normal operating temperature to a transition temperature and to apply the service load to the fuel cell when the temperature of the fuel cell is approximately the normal operating temperature.

2. The apparatus of claim 1 including means for purging/passivating the fuel cell responsive to the processor, and where the program includes means for initiating the purging/passivation of the fuel cell when the temperature of the fuel cell is below approximately the transition temperature.

3. The apparatus of claim 1 including means for purging/passivating the fuel cell and wherein the load control means includes means for applying a second load less than the service load to the fuel cell, and wherein the first means includes;

means for instructing the load control means to remove the service load from the fuel cell,

means for instructing the load control means to apply the idle load to the fuel cell,

means for instructing the cooling system to reduce the temperature of the fuel cell to a transition temperature between the second and operating temperatures,

means for instructing the load control means to remove the idle load from the fuel cell,

means for instructing the load control means to apply the second load to the fuel cell, and

means for instructing the cooling system to reduce the temperature of the fuel cell to the second temperature.