FUEL CELL SYSTEM AND ITS CONTROL METHOD

• US 20100203409A1
• Filed: 07/23/2008
• Published: 08/12/2010
• Est. Priority Date: 07/30/2007
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Imanishi, Hiroyuki, Manabe, Kota, Ogawa, Tomoya
• Granted Patent: US 8,859,157 B2
• Time in Patent Office: Days
• US Class Current: 429/431
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 8/04037 Electrical heating
• CPC Class Codes: H01M 8/04268 Heating of fuel cells during the start-up of the fuel cells
• CPC Class Codes: H01M 8/04335 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04358 of the coolant
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04388 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04395 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04492 Humidity; Ambient humidity; Water content
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04649 of fuel cell stacks
• CPC Class Codes: H01M 8/04731 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04873 of the individual fuel cell
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/04902 of the individual fuel cell
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• 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

A fuel cell system includes; a fuel cell which generates electricity by using a fuel gas and an oxidant gas as reaction gases; current control means which controls current of a fuel cell; voltage control means which controls voltage of the fuel cell; and heat value control means which calculates a heat value required by the fuel cell system and decides a target current value of the current control means and a target voltage value of the voltage control means so as to generate the calculated necessary heat amount, thereby controlling the heat value. Thus, it is possible to supply a heat required for the fuel cell system without increasing the size of the fuel cell system.

Claims

1. A fuel cell system comprising:

a fuel cell that generates electric power using a fuel gas and an oxidizing gas as reaction gases;

a current controlling section that controls a current of the fuel cell so that the current becomes a target current value;

a voltage controlling section that controls a voltage of the fuel cell so that the voltage becomes a target voltage value; and

a heat generation quantity controlling section that controls a heat generation quantity, by calculating a necessary heat quantity that is necessary for the fuel cell system and determining the target current value of the current controlling section and a target voltage value of the voltage controlling section so as to generate heat in the necessary required heat quantity, wherein

the heat generation quantity controlling section determines that the target current value=(Q+P)/Vmax, and the target voltage value=(Vmax*P)/(Q+P), where P is required output power, which is required output power for the fuel cell, Q is the necessary heat quantity, and Vmax is an electromotive force as a theoretical output voltage of the fuel cell.

2. The fuel cell system as set forth in claim 1, further comprising:

a heating apparatus using the heat generated by the fuel cell as a heat source; and

wherein

the necessary heat quantity includes a heating heat quantity necessary for the heating apparatus that is operating.

3. The fuel cell system as set forth in claim 1, wherein the necessary heat quantity includes a warm-up heat quantity necessary for warming up the fuel cell.

4. The fuel cell system as set forth in claim 1, wherein the necessary heat quantity includes a temperature-maintaining heat quantity necessary for maintaining the temperature of the fuel cell system at a predetermined temperature.

5. The fuel cell system as set forth in claim 1, wherein the controlling section performs control with low-efficiency power generation in which power generation efficiency is lower than that in high-efficiency power generation of the fuel cell.

6. The fuel cell system as set forth in claim 1, wherein the voltage controlling means section is a DC/DC converter, and the current controlling means section is a reaction gas supplying means section.

7. A fuel cell system comprising:

a fuel cell that generates electric power using a fuel gas and an oxidizing gas as reaction gases;

a secondary battery that is charged by output power of the fuel cell, or that discharges charged electric power; and

a voltage controlling section that controls a voltage of the secondary battery, the fuel cell system comprising;

a controlling section that, by calculating a necessary heat quantity that is necessary for the fuel cell system and a required output power required therefore, and based on the calculated necessary heat quantity and required output power, controls the fuel cell so as to operate in any of a plurality of modes including a high-efficiency power generation mode in which the fuel cell is caused to generate power at high efficiency;

a first low-efficiency power generation mode in which a lower limit voltage value is set at a first lower limit voltage value and power generation efficiency is lower than that of the high-efficiency power generation; and

a second low-efficiency power generation mode in which the lower limit voltage value is a second lower limit voltage value that is less than the first lower limit voltage value.

9. The fuel cell system as set forth in claim 7, further comprising:

a heating apparatus using the heat generated by the fuel cell as a heat source; and

wherein

the necessary heat quantity includes a heating heat quantity necessary for the heating apparatus that is operating.

10. The fuel cell system as set forth in claim 7, wherein the necessary heat quantity includes a warm-up heat quantity necessary for warming up the fuel cell.

11. The fuel cell system as set forth in claim 7, wherein the necessary heat generation quantity includes a temperature-maintaining heat quantity necessary for maintaining the temperature of the fuel cell system at a predetermined temperature.

12. The fuel cell system as set forth in claim 7, wherein the controlling section increases the amount of the reaction gases supplied to the fuel cell when shifting from the first low-efficiency power generation mode or the second low-efficiency power generation mode to the high-efficiency power generation mode.

8. A fuel cell system comprising:

a fuel cell that generates electric power using a fuel gas and an oxidizing gas as reaction gases; and

a voltage controlling section that controls a voltage of the fuel cell,

the fuel cell system further comprising a controlling section that controls the fuel cell, based on a necessary heat quantity that is necessary for the fuel cell system and a required output power required therefore, so as to operate in any of a plurality of modes including a high-efficiency power generation mode in which the fuel cell is caused to generate power at high efficiency; and

a second low-efficiency power generation mode in which a lower limit voltage value is a second lower limit voltage value and power generation efficiency is lower than that of the high-efficiency power generation.

17. The fuel cell system as set forth in claim 8, further comprising:

a heating apparatus using the heat generated by the fuel cell as a heat source; and

wherein

the necessary heat quantity includes a heating heat quantity necessary for the heating apparatus that is operating.

18. The fuel cell system as set forth in claim 8, wherein the necessary heat quantity includes a warm-up heat quantity necessary for warming up the fuel cell.

19. The fuel cell system as set forth in claim 8, wherein the necessary heat generation quantity includes a temperature-maintaining heat quantity necessary for maintaining the temperature of the fuel cell system at a predetermined temperature.

20. The fuel cell system as set forth in claim 8, wherein the controlling section increases the amount of the reaction gases supplied to the fuel cell when shifting from the first low-efficiency power generation mode or the second low-efficiency power generation mode to the high-efficiency power generation mode.

13. A method of controlling a fuel cell system comprising:

a first step of obtaining a necessary heat quantity that is necessary for the fuel cell system, and a required output power required therefore;

a second step of obtaining an operating point determined by a current value and a voltage value that satisfy the necessary heat quantity and the required output power in a current-voltage curve of a fuel cell determined by a supply condition of a reaction gas; and

a third step of controlling the current value and the voltage value of the fuel cell so that electric power generation of the fuel cell is performed at the operating point.

14. The method of controlling the fuel cell system as set forth in claim 13, wherein:

the fuel cell system comprises a heating apparatus that uses heat generated by the fuel cell as a heat source; and

the necessary heat quantity includes a heating heat quantity necessary for the heating apparatus that is being operated, and a warm-up heat quantity necessary for warming up the fuel cell.

15. The method of controlling the fuel cell system as set forth in claim 13, wherein the required output power includes a driving force required by a vehicle incorporating the fuel cell system, and an output power required by an auxiliary machine of the fuel cell system.

16. The method of controlling the fuel cell system as set forth in claim 13, wherein the fuel cell system comprises a converter for setting an operating point.