FUEL CELL SYSTEM

• US 20110014536A1
• Filed: 03/03/2009
• Published: 01/20/2011
• Est. Priority Date: 03/25/2008
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Yoshida, Michio
• Granted Patent: US 9,017,888 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• 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 8/04313 characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
• CPC Class Codes: H01M 8/04395 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04798 of fuel cell reactants
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The invention prevents a fuel cell from going into a high-voltage state upon activation. In a fuel cell system having a fuel cell that is supplied with reactant gases and generates power from an electrochemical reaction of the reactant gases, a compressor that supplies the fuel cell with oxidizing gas which is one of the reactant gases, and a control unit 6 that performs various types of processing, the control unit performs: high-voltage-prevention processing that prevents, under a condition permitting high-voltage prevention, a high-voltage state by reducing the output voltage of the fuel cell to less than or equal to a predetermined high-voltage-prevention voltage; output-limitation processing that limits the fuel cell output by reducing the amount of power generation by the fuel cell to less than or equal to a predetermined power generation limit, so that the oxidizing gas stoichiometric ratio is maintained within a predetermined allowable range; determination processing that determines whether or not the oxidizing gas supply is sufficient with respect to a required amount of supply; and prohibition processing that prohibits the output-limitation processing upon activation of the fuel cell until the oxidizing gas supply is determined as being sufficient.

Claims

1. A fuel cell system comprising:

a fuel cell that is supplied with reactant gases and generates power from an electrochemical reaction of the reactant gases;

a high-voltage prevention unit that, under a predetermined condition permitting high-voltage prevention, prevents a high-voltage state by reducing an output voltage of the fuel cell to less than or equal to a predetermined high-voltage-prevention voltage;

a compressor that supplies the fuel cell with oxidizing gas which is one of the reactant gases;

an output limitation unit that limits an output from the fuel cell by reducing an amount of power generation by the fuel cell to less than or equal to a predetermined power generation limit which is lower than a required power generation amount, so that a stoichiometric ratio of the oxidizing gas is maintained within a predetermined allowable range; and

a prohibition unit that prohibits the limitation by the output limitation unit for a predetermined period of time immediately after the fuel cell is activated and where the condition permitting high-voltage prevention is satisfied.

2. The fuel cell system according to claim 1, the predetermined period of time is a period from activation of the fuel cell until the oxidizing gas supply meets a required amount of supply.

3. The fuel cell system according to claim 2, further comprising a determination unit that determines whether or not the oxidizing gas supply meets the require amount of supply,

wherein the prohibition unit prohibits the limitation by the output limitation unit upon activation of the fuel cell until the determination unit determines that the oxidizing gas supply meets the required amount of supply.

4. The fuel cell system according to claim 3, further comprising a rotation frequency sensor that detects a rotation frequency of a motor of the compressor,

wherein the determination unit determines that the oxidizing gas supply does not meet the required amount of supply if there is a gap between the rotation frequency detected by the rotation frequency sensor and a rotation frequency directed to the compressor.

5. The fuel cell system according to claim 4, wherein the determination unit determines that the oxidizing gas supply does not meet the required amount of supply if the rotation frequency detected by the rotation frequency sensor is smaller than the rotation frequency directed to the compressor.

6. The fuel cell system according to claim 1, wherein the predetermined period of time is a period from activation of the fuel cell until both of the power generation limit and the required power generation amount for the fuel cell increase to greater than or equal to a high-voltage-prevention power generation amount which corresponds to the high-voltage-prevention voltage.

7. The fuel cell system according to claim 6, further comprising a determination unit that determines whether or not both of the power generation limit and the required power generation amount are greater than or equal to the high-voltage-prevention power generation amount,

wherein the prohibition unit prohibits the limitation by the output limitation unit upon activation of the fuel cell until the determination unit determines that the power generation limit and the required power generation amount are greater than or equal to the high-voltage-prevention power generation amount.

8. The fuel cell system according to claim 1, wherein the activation of the fuel cell is an activation following completion of an intermittent operation in the fuel cell.

9. The fuel cell system according to claim 1, further comprising a cancellation unit that cancels the prohibition by the prohibition unit when a predetermined period of time has passed from the activation of the fuel cell.