FUEL CELL SYSTEM

• US 20100055521A1
• Filed: 01/31/2008
• Published: 03/04/2010
• Est. Priority Date: 02/05/2007
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Taniyama, Motohiko, Yoshida, Michio, Umayahara, Kenji, Matsumoto, Tadaichi
• Granted Patent: US 9,034,495 B2
• Time in Patent Office: Days
• US Class Current: 429/429
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04858 Electric variables
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

To provide a fuel cell system that can both improve power generation efficiency of a fuel cell and maintain durability of the fuel cell. A fuel cell system performs control such that when a power requirement for the fuel cell is lower than a predetermined value, a supply of a reaction gas to a fuel cell is stopped to keep an output voltage from the fuel cell equal to a high-potential avoidance voltage that is lower than an open end voltage. The fuel cell system further controls the output voltage from the fuel cell with the high-potential avoidance voltage set to be an upper limit when the power requirement for the fuel cell is equal to or higher than a predetermined value. By setting the upper limit of the output voltage of the fuel cell to be the high-potential avoidance voltage, which is lower than the open end voltage, the catalyst can be inhibited from being degraded by an increase in the output voltage from the fuel cell up to the open end voltage.

Claims

1. A fuel cell system comprising:

a fuel cell which receives a supplied reaction gas to generate power, and

a control device which, when a power requirement for the fuel cell is lower than a predetermined value, controllably stops supply of the reaction gas to the fuel cell and keeps an output voltage from the fuel cell equal to a high-potential avoidance voltage which is lower than an open end voltage and, when the power requirement for the fuel cell is equal to or higher than the predetermined value, controls the output voltage from the fuel cell with the high-potential avoidance voltage set to be an upper limit.

2. The fuel cell system according to claim 1, further comprising a DC/DC converter that controls the output voltage from the fuel cell,

wherein when the power requirement for the fuel cell is lower than the predetermined value, the control device stops driving of the DC/DC converter when the output voltage from the fuel cell becomes lower than the high-potential avoidance voltage by a predetermined voltage.

3. The fuel cell system according to claim 1, further comprising an electric storage device,

wherein if power generated by the fuel cell exceeds the sum of power which can be charged by the electric storage device and power which can be consumed by an auxiliary device, the control device permits the output voltage from the fuel cell to increase up to the open end voltage.

4. The fuel cell system according to claim 1, further comprising a traction motor,

wherein while the traction motor is performing regenerative braking, the control device permits the output voltage from the fuel cell to increase up to the open end voltage.

5. The fuel cell system according to claim 1, further comprising a plurality of shut-off valves disposed in a pipe line through which the reaction gas is supplied to the fuel cell,

wherein the control device closes the plurality of shut-off valves to form a closed space inside the pipe line, and while detecting a possible variation in a gas pressure inside the closed space to detect possible gas leakage, the control device permits the output voltage from the fuel cell to increase up to the open end voltage.

6. The fuel cell system according to claim 1, wherein the fuel cell is a cell stack comprising a plurality of stacked cells, and the control device corrects the high-potential avoidance voltage so that highest one of output voltages from the plurality of cells is equal to or lower than a predetermined value.