State determination device and method for fuel cell

Patent metadata

Field	Value
Publication number	US-9917315-B2
Application number	US-201415524104-A
Country	US
Kind code	B2
Filing date	Nov 7, 2014
Priority date	Nov 7, 2014
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

A state determination device for a fuel cell for generating power upon receiving the supply of anode gas and cathode gas, comprising: an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell; and an anode reaction resistance estimation/calculation unit configured to calculate an estimation value of a reaction resistance of an anode electrode of the fuel cell on the basis of a measurement value of the internal impedance, wherein: the predetermined frequency is selected such that a difference between the estimation value of the reaction resistance of the anode electrode during hydrogen starvation and the estimation value of the reaction resistance of the anode electrode during oxygen starvation is not smaller than a predetermined value.

First claim

The invention claimed is:

1. A state determination device for a fuel cell for generating power upon receiving the supply of anode gas and cathode gas, comprising:
an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell; and
an anode reaction resistance estimation/calculation unit configured to calculate an estimation value of a reaction resistance of an anode electrode of the fuel cell on the basis of a measurement value of the internal impedance,
wherein:
the predetermined frequency is selected such that a difference between the estimation value of the reaction resistance of the anode electrode during hydrogen starvation and the estimation value of the reaction resistance of the anode electrode during oxygen starvation is not smaller than a predetermined value.

2. The state determination device for the fuel cell according to claim 1 , comprising:
an electrolyte wet/dry state measurement unit configured to measure a wet/dry state of an electrolyte membrane of the fuel cell on the basis of the measurement value of the internal impedance, wherein:
the internal impedance measurement unit measures an internal impedance of a high frequency higher than the predetermined frequency; and
the electrolyte wet/dry state measurement unit measures the wet/dry state of the electrolyte membrane of the fuel cell on the basis of a measurement value of the internal impedance of the high frequency.

3. The state determination device for the fuel cell according to claim 1 , wherein:
the anode reaction resistance estimation/calculation unit calculates the estimation value of the reaction resistance of the anode electrode by applying the measurement value of the internal impedance to an equation for an impedance based on an equivalent circuit model of the fuel cell.

4. The state determination device for the fuel cell according to claim 1 , wherein:
the anode reaction resistance estimation/calculation unit calculates the estimation value of the reaction resistance of the anode electrode on the basis of an imaginary component of the internal impedance.

5. The state determination device for the fuel cell according to claim 4 , wherein the anode reaction resistance estimation/calculation unit:
calculates the imaginary component Z im of the internal impedance on the basis of an equation determined by an equivalent circuit model of the fuel cell, the equation being as follows:

Z
=

R
m

+

R
a

⁡

(

1
-

j
⁢

⁢
ω
⁢

⁢

C
a

⁢

R
a

)

1
+

ω
2

⁢

C
a
2

⁢

R
a
2

[

Equation
⁢

⁢
1

]

(where Z denotes the internal impedance of the fuel cell, j denotes an imaginary unit, ω denotes an angular frequency of the alternating-current signal, R m denotes an electrolyte membrane resistance value, R a denotes the estimation value of the reaction resistance value of the anode electrode and C a denotes an electrical double layer capacitance of the anode electrode); and
plots two points using frequencies ω 1 and ω 2 and measurement values Z im1 and Z im2 of imaginary components of internal impedances corresponding to the respective frequencies ω 1 and ω 2 on a coordinate system with 1/ω 2 represented on a horizontal axis and −1/ωZ im represented on a vertical axis, calculates a gradient and an intercept of a straight line obtained by connecting the two points and obtains the estimation value of the reaction resistance of the anode electrode on the basis of the calculated gradient and intercept.

6. The state determination device for the fuel cell according to claim 1 , wherein:
the anode reaction resistance estimation/calculation unit calculates the estimation value of the reaction resistance of the anode electrode on the basis of a real component of the internal impedance.

7. The state determination device for the fuel cell according to claim 6 , wherein the anode reaction resistance estimation/calculation unit:
calculates the real component Z re of the internal impedance on the basis of an equation determined by an equivalent circuit model of the fuel cell, the equation being as follows:

Z
=

R
m

+

R
a

⁡

(

1
-

j
⁢

⁢
ω

Assignees

• Nissan Motor

Inventors

• Aoki Tetsuya

Classifications

• H01M8/10

  Fuel cells with solid electrolytes · CPC title

• H01M8/04641

  of the individual fuel cell · CPC title

• H01M8/04559

  of fuel cell stacks · CPC title

• H01M8/04589

  of fuel cell stacks · CPC title

• H01M8/04649

  of fuel cell stacks · CPC title