Method and system for controlling output current of fuel cell stack

Patent metadata

Field	Value
Publication number	US-10700371-B2
Application number	US-201715654166-A
Country	US
Kind code	B2
Filing date	Jul 19, 2017
Priority date	Oct 26, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

Disclosed are a method and a system for controlling an output current of a fuel cell stack. The method of controlling the output current of the fuel cell stack, whereby the output current is controlled by using a data map configured with a limited output current according to a temperature of a fuel cell coolant, includes: deriving an average cell voltage value and a minimum cell voltage value of a plurality of cells constituting the fuel cell stack; correcting the data map by using the derived average cell voltage value and the derived minimum cell voltage value; and limiting the output current of the fuel cell according to the corrected data map.

First claim

What is claimed is:

1. A method of controlling an output of a fuel cell stack whereby an output current is controlled by using a data map stored in a memory and configured with a limited output current corresponding to a temperature of a fuel cell coolant, the method comprising:
sensing, by a sensor, voltages of a plurality of cells constituting the fuel cell stack;
deriving, by a controller, an average cell voltage value and a minimum cell voltage value of the plurality of cells based on the sensed voltages;
determining, by the controller, whether to correct the data map based on the derived average cell voltage value and the derived minimum cell voltage value;
when the data map is determined to be corrected, correcting, by the controller, the data map by varying the limited output current corresponding to the temperature of the fuel cell coolant according to the derived average cell voltage value and the derived minimum cell voltage value; and
controlling, by the controller, the output current of the fuel cell stack to be limited to the varied limited output current according to the corrected data map.

2. The method of claim 1 , further comprising:
when the data map has been corrected, storing, by the controller, the corrected data map in the memory, and limiting the output current of the fuel cell stack by using the stored data map when starting of the fuel cell stack is performed afterwards.

3. The method of claim 1 , further comprising:
calculating a cell voltage ratio by dividing the minimum cell voltage value by the average cell voltage value; and
calculating a cell voltage deviation by subtracting the minimum cell voltage value from the average cell voltage value.

4. The method of claim 3 , wherein in the correcting of the data map, the data map is corrected by using the minimum cell voltage value, the cell voltage ratio, and the cell voltage deviation.

5. The method of claim 1 , wherein the data map is a graph whereby an X-axis is for the temperature of the fuel cell coolant and a y-axis is for the limited output current, and the limited output current tends to increase as the temperature of the fuel cell coolant increases in the graph, but the limited output current is bounded by a maximum value and a minimum value, and a slope of a line in the graph gradually increases as the temperature of the fuel cell coolant increases within a range from the minimum value to the maximum value.

6. The method of claim 5 , wherein the graph includes: an inflection point referred to a point C at which the limited output current starts to increase from the minimum value, an inflection point referred to a point A at which the slope of the line in the graph is changed to increase within the range from the minimum value to the maximum value, and an inflection point referred to a point B at which the limited output current is saturated to the maximum value.

7. The method of claim 6 , wherein in the correcting of the data map, positions of the point A, the point B, or the point C within the graph are changed using the cell voltage ratio obtained by dividing the minimum cell voltage value by the average cell voltage value, a cell voltage deviation obtained by subtracting the minimum cell voltage value from the average cell voltage value, and the minimum cell voltage value.

8. The method of claim 7 , wherein in the correcting of the data map, the graph is corrected by deriving a correction factor K and coordinates of the points A, B, and C by using a following formula:

K
-

cell
⁢

⁢
voltage
⁢

⁢
ratio

minimum
⁢

⁢
cell
⁢

⁢
voltage
⁢

⁢
value
*
cell
⁢

⁢
voltage
⁢

⁢
deviation

,

10
≤
K
≤
200

Cx
=

number
⁢

⁢
of
⁢

⁢
cells

100

Cy
=

number
⁢

⁢
of
⁢

⁢
cells
*
0.3

Ax
=

(

number
⁢

⁢
of
⁢

⁢
cells

10

*
Cx

K

)

-
Cx
+

number
⁢

⁢
of
⁢

⁢
cells

10

Ay
=

(

By
⁢

⁢
Cy

)

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Park Jeong Kyu

Classifications

• Y02E60/50

  Fuel cells · CPC title

• Y02T90/40

  Application of hydrogen technology to transportation, e.g. using fuel cells · CPC title

• B60L58/32

  for controlling the temperature of fuel cells, e.g. by controlling the electric load · CPC title

• H01M8/04559

  of fuel cell stacks · CPC title

• B60L58/33

  by cooling · CPC title