Fuel cell system and method for controlling fuel cell system

Patent metadata

Field	Value
Publication number	US-2016197367-A1
Application number	US-201414902989-A
Country	US
Kind code	A1
Filing date	May 9, 2014
Priority date	Jul 5, 2013
Publication date	Jul 7, 2016
Grant date	—

Abstract

A fuel cell system supplies anode gas and cathode gas to a fuel cell and generates electric power in accordance with a load. The fuel cell system configured to include a cathode gas control unit controls a pressure of the cathode gas on the basis of the load, an anode gas control unit configured to cause a pressure of the anode gas to pulsate on the basis of the pressure of the cathode gas and a pulsation amplitude. The pulsation amplitude is determined on the basis of an operating condition of the fuel cell. The fuel cell system includes an anode gas partial pressure maintenance control unit configured to increase the pressure of the anode gas in accordance with a condition of an impurity within the fuel cell. The cathode gas control unit configured to make the pressure of the cathode gas higher when a pressure difference between the pressure of the anode gas and the pressure of the cathode gas is large than when the pressure difference is small.

First claim

1 .- 10 . (canceled)

11 . A fuel cell system for supplying anode gas and cathode gas to a fuel cell and for generating electric power in accordance with a load, the fuel cell system comprising:
a cathode gas control unit configured to control a pressure of the cathode gas on the basis of the load; an anode gas control unit configured to cause a pressure of the anode gas to pulsate between an upper limit pressure and a lower limit pressure determined on the basis of the pressure of the cathode gas and an operating condition of the fuel cell; and an anode gas partial pressure maintenance control unit configured to increase the pressure of the anode gas in accordance with a condition of an impurity within the fuel cell, wherein the cathode gas control unit sets a target pressure of the cathode gas on the basis of the upper limit pressure of the anode gas when a pressure difference between the pressure of the anode gas and the pressure of the cathode gas has increased by controlling the pressure of the anode gas by the anode gas partial pressure maintenance control unit so as to be increased.

12 . The fuel cell system according to claim 11 , wherein
the anode gas partial pressure maintenance control unit increases a pulsation upper limit pressure and a pulsation lower limit pressure of the anode gas in response to an increase in a partial pressure of the impurity within the fuel cell, the pulsation upper limit pressure and the pulsation lower limit pressure being controlled by the anode gas control unit, and when the anode gas partial pressure maintenance control unit increases the pulsation upper limit pressure, the cathode gas control unit increases the target pressure of the cathode gas so that the pressure difference does not exceed an allowable pressure for protecting the fuel cell.

13 . The fuel cell system according to claim 12 , wherein
the anode gas partial pressure maintenance control unit makes the pulsation lower limit pressure controlled by the anode gas control unit higher than the pressure of the cathode gas supplied to the fuel cell in accordance with the condition of the impurity within the fuel cell.

14 . The fuel cell system according to claim 11 , wherein
when the pressure difference exceeds an allowable pressure for protecting the fuel cell, the cathode gas control unit increases the target pressure of the cathode gas.

15 . The fuel cell system according to claim 12 , wherein
the anode gas partial pressure maintenance control unit calculates a lower limit partial pressure of the anode gas on the basis of the condition of the impurity within the fuel cell, the anode gas control unit includes:
a lower limit setting unit configured to set a higher one of the lower limit partial pressure of the anode gas and the pressure of the cathode gas as a pulsation lower limit pressure of the anode gas; and
an upper limit setting unit configured to set a pressure obtained by adding the pulsation lower limit pressure and a pulsation amplitude as a pulsation upper limit pressure of the anode gas,
the anode gas control unit causes the pressure of the anode gas to pulsate on the basis of the pulsation upper limit pressure and the pulsation lower limit pressure, and the cathode gas control unit includes:
a computation unit configured to compute a required pressure of the cathode gas on the basis of the load, and
a pressure difference adjustment unit configured to make the target pressure of the cathode gas higher than the required pressure of the cathode gas on the basis of the pulsation upper limit pressure when a pressure difference between the pulsation upper limit pressure of the anode gas and the required pressure of the cathode gas exceeds the allowable pressure.

16 . The fuel cell system according to claim 15 , wherein
when the pulsation upper limit pressure exceeds a limit pressure for preventing an excessive pressure of the anode gas, the pressure difference adjustment unit stops an increase in the target pressure of the cathode gas.

17 . The fuel cell system according to claim 16 , wherein
the pressure difference adjustment unit makes the target pressure of the cathode gas higher than the required pressure by a difference obtained by subtracting the limit pressure from the pulsation upper limit pressure.

18 . The fuel cell system according to claim 16 , wherein
the pressure difference adjustment unit makes the target pressure of the cathode gas higher than the required pressure by a difference obtained by subtracting the allowable pressure from the pressure difference.

19 . The fuel cell system according to claim 15 , wherein
the impurity is water vapor produced through generation of the electric power, and the pressure difference adjustment unit calculates the lower limit pressure of the anode gas on the basis of a temperature of the fuel cell, and calculates the pulsation upper limit pressure of the anode gas by adding the lower limit pressure to the pulsation amplitude.

20 . The fuel cell system according to claim 15 , wherein
the pressure difference adjustment unit includes:
a calculation unit configured to calculate a lower limit pressure of the cathode gas by subtracting the allowable pressure from a lower one of the pressure of the anode gas set by the upper limit setting unit and a limit pressure for preventing an excessive pressure of the anode gas, and
a pressure setting unit configured to set a higher one of the lower limit pressure of the cathode gas and the required pressure as the target pressure of the cathode gas.

21 . The fuel cell system according to claim 15 , wherein
the upper limit setting unit makes the pulsation upper limit pressure of the anode gas higher for a higher temperature of the fuel cell, and when the pressure difference exceeds the allowable pressure, the pressure difference adjustment unit makes the target pressure of the cathode gas higher for a higher pulsation upper limit pressure of the anode gas.

22 . A method of controlling a fuel cell system for supplying anode gas and cathode gas to a fuel cell and for generating electric power in accordance with a load, the method comprising:
a cathode gas control step of controlling a pressure of the cathode gas on the basis of the load; an anode gas control step of causing a pressure of the anode gas to pulsate between an upper limit pressure and a lower limit pressure determined on the basis of the pressure of the cathode gas and an operating condition of the fuel cell; and an anode gas partial pressure maintenance control step of increasing the pressure of the anode gas in accordance with a condition of an impurity within the fuel cell, wherein in the anode gas partial pressure maintenance control step, a target pressure of the cathode gas is set on the basis of the upper limit pressure of the anode gas when a pressure difference between the pressure of the anode gas and the pressure of the cathode gas has increased by controlling the pressure of the anode gas to be increased in the anode gas partial pressure maintenance control step.

Assignees

• Nissan Motor

Inventors

• Chikugo Hayato

Classifications

• H01M8/04104 Primary

  Regulation of differential pressures · CPC title

• H01M8/04231 Primary

  Purging of the reactants · CPC title

• H01M8/04388

  of anode reactants at the inlet or inside the fuel cell · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/04395

  of cathode reactants at the inlet or inside the fuel cell · CPC title