State detection device and method for fuel cell

Patent metadata

Field	Value
Publication number	US-10115987-B2
Application number	US-201515554242-A
Country	US
Kind code	B2
Filing date	Mar 3, 2015
Priority date	Mar 3, 2015
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A state detection device for fuel cell includes a supposed high-frequency impedance value setting unit configured to set a supposed high-frequency impedance value on the basis of an impedance measurement value belonging to an arc region of an impedance curve of the fuel cell, an actually measured high-frequency impedance value calculation unit configured to obtain an actually measured high-frequency impedance value on the basis of an impedance measurement value belonging to a non-arc region of the impedance curve of the fuel cell, and an ionomer resistance estimation unit configured to estimate a value obtained by subtracting the actually measured high-frequency impedance value from the supposed high-frequency impedance value as an ionomer resistance value. The supposed high-frequency impedance value setting unit sets a value of an intersection of an equivalent circuit impedance curve set on the basis of the impedance measurement value belonging to the arc region and a real ads as the supposed high-frequency impedance value.

First claim

The invention claimed is:

1. A state detection device for fuel cell, comprising
a controller programmed to:
set a predetermined high-frequency impedance value on the basis of an impedance measurement value belonging to an arc region of an impedance curve of the fuel cell;
obtain an actually measured high-frequency impedance value on the basis of an impedance measurement value belonging to a non-arc region of the impedance curve of the fuel cell;
estimate a value obtained by subtracting the actually measured high-frequency impedance value from the predetermined high-frequency impedance value as an ionomer resistance value; and
set a value of an intersection of an equivalent circuit impedance curve set on the basis of an impedance measurement value belonging to the arc region and a real axis as the predetermined high-frequency impedance value.

2. The state detection device for fuel cell according to claim 1 , wherein:
the equivalent circuit impedance curve is set by applying the impedance measurement value belonging to the arc region to an equation for impedance obtained from an equivalent circuit of the fuel cell.

3. The state detection device for fuel cell according to claim 2 , wherein:
the equivalent circuit impedance curve is set by applying real parts and imaginary parts of impedance measurement values at two or more frequencies in the arc region to an equation for impedance real part:

R

cell
,
sup

=

Z
re

-

R
act

1
+

ω
2

⁢

C
dl
2

⁢

R
act
2

[

Equation
⁢

⁢
1

]

 and
an equation for imaginary part obtained from the equivalent circuit:

-

1

ω
⁢

⁢

Z

i
⁢

⁢
m

=

1

ω
2

⁢

C
dl

⁢

R
act
2

+

C
dl

[

Equation
⁢

⁢
2

]

where Z re , Z im respectively denote the real part and the imaginary part of the impedance of the fuel cell, ω denotes an angular frequency of an alternating-current signal, R cell,sup denotes the predetermined high-frequency impedance value, R act denotes a reaction resistance of a cathode electrode and C dl denotes an electrical double layer capacitance of the cathode electrode.

4. The state detection device for fuel cell according to claim 1 wherein the controller is further programmed to:
obtain an increase of an ionomer resistance value by comparing a reference value of the ionomer resistance value estimated under a reference operating condition and a post-deterioration ionomer resistance value estimated after the fuel cell is operated for a predetermined time from an estimated value under the reference operating condition; and
make a correction by subtracting the increase from a current estimated value of the ionomer resistance value.

5. The state detection device for fuel cell according to claim 4 , wherein:
the state detection device detects a deteriorated state of a catalyst layer of the fuel cell on the basis of the current estimated value of the ionomer resistance value, which has been corrected.

6. The state detection device for fuel cell according to claim 1 , wherein the controller is further programmed to:
estimate an electrolyte membrane resistance value;
compare a reference electrolyte membrane resistance value set on the basis of a relationship between the estimated ionomer resistance value and a wet/dry state of the fuel cell and a post-deterioration actually measured high-frequency impedance value estimated after the fuel cell is operated for a predetermined time from the set to obtain a difference between these; and
make a correction by subtracting the difference from a current measurement value of the actually measured high-frequency impedance value.

7. The state detection device for fuel cell according to claim 1 , wherein the controller is further programmed to:
obtain two or more candidates for the predetermined high-frequency impedance value on the basis of two or more impedance measurement values belonging to the arc region; and
set an average value of the two or more candidates for the predetermined high-frequency impedance value as the predetermined high-frequency impedance value.

8. The state d

Assignees

• Nissan Motor

Inventors

• Kotaka Toshikazu
• Aoki Tetsuya

Classifications

• H01M8/04634 Primary

  Other electric variables, e.g. resistance or impedance · CPC title

• H01M8/1039

  halogenated, e.g. sulfonated polyvinylidene fluorides · CPC title

• H01M8/0485

  of the electrolyte · CPC title

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title