METHOD AND SYSTEM FOR CONTROLLING OUTPUT CURRENT OF FUEL CELL STACK

• US 20180114996A1
• Filed: 07/19/2017
• Published: 04/26/2018
• Est. Priority Date: 10/26/2016
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group), Kia Motors Corporation (Kia Corp.)
• Inventors: PARK, Jeong Kyu
• Granted Patent: US 10,700,371 B2
• Time in Patent Office: Days
• CPC Class Codes: B60L 50/72 Constructional details of fuel cells specially adapted for electric vehicles
• CPC Class Codes: B60L 58/32 for controlling the temperature of fuel cells, e.g. by controlling the electric load
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 8/04358 of the coolant
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

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.

Claims

1. A method of controlling an output of a fuel cell stack whereby an output current is controlled by using a data map configured with a limited output current according to a temperature of a fuel cell coolant, the method comprising:

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 stack according to the corrected data map.

2. The method of claim 1, when the data map is corrected, the method further includes:

updating the corrected data map in a memory, and limiting the output current of the fuel cell stack by using the updated 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.

9. The method of claim 8, wherein in the correcting of the data map, the graph is corrected by deriving the x and y coordinates of the points A, B, and C when the derived correction factor K becomes smaller than a previous correction factor.

10. The method of claim 1, wherein the correcting of the data map is performed when a demanded output of the fuel cell stack is equal to or greater than a certain level, a cell voltage ratio obtained by dividing the minimum cell voltage value by the average cell voltage value is equal to or less than a first reference value, and a cell voltage deviation obtained by subtracting the minimum cell voltage value from the average cell voltage value is equal to or greater than a second reference value.

11. A method of controlling an output of a fuel cell stack whereby an output current is controlled by using a data map configured with a limited output current according to a temperature of a fuel cell coolant, the method comprising:

deriving, by a controller, an average cell voltage value and a minimum cell voltage value of a plurality of cells constituting the fuel cell stack by using a sensor provided in the fuel cell stack;

correcting, by the controller, the data map stored in a memory by using the derived average cell voltage value and the derived minimum cell voltage value; and

limiting, by the controller, the output current of the fuel cell stack according to the corrected data map stored in the memory.

12. A system for controlling an output of a fuel cell stack, the system comprising:

a sensor sensing voltages of a plurality of cells constituting the fuel cell stack;

a memory storing a data map configured with a limited output current according to a temperature of a fuel cell coolant; and

a controller deriving an average cell voltage value and a minimum cell voltage value of the 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 stack according to the corrected data map.