FUEL CELL SYSTEM

• US 20130244127A1
• Filed: 03/11/2013
• Published: 09/19/2013
• Est. Priority Date: 03/15/2012
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: ICHIKAWA, Yasushi, FUJII, Takahiro, SHIMOI, Ryoichi, MAESHIMA, Susumu, IKEZOE, Keigo, NISHIYAMA, Taiji, ITO, Yusuke
• Granted Patent: US 9,147,896 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04634 Other electric variables, e.g. resistance or impedance
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system is basically provided with a fuel cell, a pressure adjusting valve, a purge valve and an anode pressure controller. The fuel cell includes an anode that receives an anode gas and a cathode that receives a cathode gas to generate electric power corresponding to a load. The pressure adjusting valve is disposed in a supply path to adjust anode gas pressure to the anode. The purge valve is disposed in a discharging flow path to discharge an anode-off gas containing impurities from the fuel cell. The anode pressure controller is configured to control the pressure adjusting valve to perform a pulsation operation that pulsates the anode gas pressure of the fuel cell. The anode pressure controller decreases a median pressure of the pulsation operation as a wetness level of an electrolyte membrane of the fuel cell stack is determined to become higher.

Claims

1. A fuel cell system comprising

a fuel cell including an anode that receives an anode gas and a cathode that receives a cathode gas to generate electric power corresponding to a load;

a pressure adjusting valve disposed in a supply path to adjust anode gas pressure to the anode;

a purge valve disposed in a discharging flow path to discharge an anode-off gas containing impurities from the fuel cell; and

an anode pressure controller configured to control the pressure adjusting valve to perform a pulsation operation that pulsates the anode gas pressure of the fuel cell,

the anode pressure controller decreasing a median pressure of the pulsation operation as a wetness level of an electrolyte membrane of the fuel cell stack is determined to become higher.

2. The fuel cell system according to claim 1, wherein

the anode pressure controller sets an upper limit pressure of the pulsation operation of the anode gas and an lower limit pressure of the pulsation operation of the anode gas, and controls the pressure adjusting valve so that the anode gas pressure pulsates between the upper limit pressure and the lower limit pressure;

and

the anode pressure controller decreases the median pressure of the pulsation operation by decreasing the lower limit pressure of the pulsation operation of the anode gas.

3. The fuel cell system according to claim 1, further comprising

an internal resistance detector that detects an internal resistance of the electrolyte membrane of the fuel cell, and the anode pressure controller determining the wetness level of the electrolyte membrane of the fuel cell based on the internal resistance of the electrolyte membrane.

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

a cell voltage detector that detects a cell voltage of the electrolyte membrane of the fuel cell, and the anode pressure controller determining the wetness level of the electrolyte membrane of the fuel cell based on the cell voltage.

5. The fuel cell system according to claim 2, wherein

the anode pressure controller resets the lower limit pressure of the pulsation operation of the anode gas upon determining a water discharging operation is not needed after the lower limit pressure of the pulsation operation of the anode gas was decreased.

6. The fuel cell system according to claim 2, wherein

the anode pressure controller further decreases the lower limit pressure of the pulsation operation of the anode gas upon determining water cannot be discharged by decreasing the lower limit pressure of the pulsation operation of the anode gas.

7. The fuel cell system according to claim 1, wherein

the anode pressure controller decreases the median pressure of the pulsation operation of the anode gas when a cell voltage of the fuel cell is lower than a reference level.

8. The fuel cell system according to claim 1, wherein

the anode pressure controller decreases the median pressure of the pulsation operation once during every prescribed time period.

9. The fuel cell system according to claim 2, wherein

the anode pressure controller increases a purge rate of the purge valve to decrease the lower limit pressure of the pulsation operation of the anode gas.

10. The fuel cell system according to claim 2, wherein

the anode pressure controller increases a decreasing magnitude amount of the lower limit pressure of the pulsation operation of the anode gas when a hydrogen concentration of a buffer tank is higher than a predetermined concentration.

11. The fuel cell system according to claim 2, further comprising

an internal resistance detector that detects an internal resistance of the electrolyte membrane of the fuel cell, and the anode pressure controller determining the wetness level of the electrolyte membrane of the fuel cell based on the internal resistance of the electrolyte membrane.

12. The fuel cell system according to claim 2, further comprising

a cell voltage detector that detects a cell voltage of the electrolyte membrane of the fuel cell, and the anode pressure controller determining the wetness level of the electrolyte membrane of the fuel cell based on the cell voltage.

13. The fuel cell system according to claim 3, wherein

the anode pressure controller resets the lower limit pressure of the pulsation operation of the anode gas upon determining a water discharging operation is not needed after the lower limit pressure of the pulsation operation of the anode gas was decreased.

14. The fuel cell system according to claim 3, wherein

the anode pressure controller further decreases the lower limit pressure of the pulsation operation of the anode gas upon determining water cannot be discharged by decreasing the lower limit pressure of the pulsation operation of the anode gas.

15. The fuel cell system according to claim 3, wherein

the anode pressure controller decreases the median pressure of the pulsation operation of the anode gas when a cell voltage of the fuel cell is lower than a reference level.

16. The fuel cell system according to claim 3, wherein

the anode pressure controller decreases the median pressure of the pulsation operation once during every prescribed time period.

17. The fuel cell system according to claim 3, wherein

the anode pressure controller increases a purge rate of the purge valve to decrease the lower limit pressure of the pulsation operation of the anode gas.

18. The fuel cell system according to claim 3, wherein

the anode pressure controller increases a decreasing magnitude amount of the lower limit pressure of the pulsation operation of the anode gas when a hydrogen concentration of a buffer tank is higher than a predetermined concentration.