Hybrid fuel battery system and the operation method thereof

• US 5,334,463 A
• Filed: 10/27/1992
• Issued: 08/02/1994
• Est. Priority Date: 11/29/1991
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamamoto, Satoshi, Sumi, Shingo, Yoneda, Fumiiki, Tajima, Osamu, Shindo, Koji
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US07/967,270
• Time in Patent Office: 644 Days
• Field of Search: 429/9, 429/13, 429/23, 429/24, 429/50
• US Class Current: 429/9
• CPC Class Codes: B60L 58/30 for monitoring or controlling fuel cells
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04373 of auxiliary devices, e.g. reformers, compressors, burners
• 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 8/04597 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04776 at auxiliary devices, e.g. reformer, compressor, burner
• CPC Class Codes: H01M 8/04888 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04917 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• 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
• CPC Class Codes: Y10S 429/90 Fuel cell including means for power conditioning, e.g. Conversion to ac

Abstract

A hybrid fuel cell system including a fuel cell for generating electric power by reacting fuel gas and oxidant gas, current restricting structure for restricting an output current of the fuel cell, a storage cell connected parallel to a series circuit comprising the fuel cell and the current restricting structure for helping the fuel cell to supply electric power to an external load, external load fluctuation detecting structure for detecting a fluctuation in the current demanded by the external load and current limitation adjusting structure for following the fluctuation in the current demanded by the external load by changing the restriction of the output current of the fuel cell which is made by the current restricting structure, with the passage of time.

Claims

1. A hybrid fuel cell system comprising:

a fuel cell for generating electric power by reacting fuel gas and oxidant gas;

current restricting means for restricting an output current of said fuel cell;

a storage cell connected parallel to a series circuit comprising said fuel cell and said current restricting means for helping the fuel cell to supply electric power to an external load;

external load fluctuation detecting means for detecting a fluctuation in the current demanded by the external load; and

current limitation adjusting means for following the fluctuation in the current demanded by the external load by changing the restriction of the output current of the fuel cell which is made by said current restricting means, with the passage of time.

2. The hybrid fuel cell system of claim 1 wherein said current restricting means is a DC/DC converter comprising a gate terminal, said gate terminal having a control signal from said current limitation adjusting means.

3. The hybrid fuel cell system of claim 2 further comprising voltage limitation adjusting means for changing a limitation of the output voltage of the DC/DC converter by monitoring a charge current of said storage cell.

4. The hybrid fuel cell system of claim 3 wherein a control signal from the voltage limitation adjusting means is given to the gate terminal of the DC/DC converter.

5. The hybrid fuel cell system of claim 4 wherein said external load fluctuation detecting means comprise first current detecting means inserted into the output current line of the fuel cell, second current detecting means inserted into a charge/discharge current line of the storage cell, adding means for adding the values detected by the first and second current detecting means and detecting means for detecting a change occurring with the passage of time in a result of adding by the adding means.

6. The hybrid fuel cell system of claim 5 wherein when the current demanded by the external load fluctuates, said current limitation adjusting means changes a limitation at a speed which enables the fuel cell to follow the fluctuation.

7. The hybrid fuel cell system of claim 6 wherein a control current I_FR of said current limitation adjusting means changes according to a formula in which I_FR '"'"' refers to an immediate past I_FR, I_L Dt refers to a time integration value of an external load current IL and

8. The hybrid fuel cell system of claim 7 wherein said voltage limitation adjusting means operates to make the fuel cell charge the storage cell when the current limitation adjusting means make the fuel cell supply the entire current to the external load.

9. The hybrid fuel cell system of claim 8 further comprising a storage cell temperature detecting means, wherein said voltage limitation adjusting means corrects the output voltage of the DC/DC converter according to a temperature of the storage cell detected by the storage cell temperature detecting means.

10. The hybrid fuel cell system of claim 9 wherein said voltage limitation adjusting means operates the following corrections, in which T refers to a detected temperature of the storage cell, T₁ a first fixed temperature, and T₂ a second fixed temperature (T₂ >

T₁);

in the case of T≦

T₁, a first voltage value is generated;

in the case of T=T2, a second voltage value, which is smaller than the first one, is generated; and

in the case of T₂ <

T<

T₂, the output voltage of the DC/DC converter gradually decreases.

11. The hybrid fuel cell system of claim 10 wherein the gate terminal of said DC/DC converter selects the more active control signal of a) said current limitation adjusting means and b) said voltage limitation adjusting means.

12. The hybrid fuel cell system of claim 1 further comprising a channel for supplying fuel gas to the fuel cell comprising a reforming device for reforming fuel gas into gas enriched with hydrogen and a fuel supply valve for controlling a quantity of fuel gas supplied to the reforming device,

wherein an opening of the valve is set in response to an output current value of the fuel cell.

13. The hybrid fuel cell system of claim 12 further comprising:

a reforming device temperature detector for detecting a temperature of a catalytic layer of the reforming device; and

a fuel supply valve opening correcting means for correcting the opening of said fuel supply valve responding to the result detected by the reforming device temperature detector,

wherein fuel supply valve opening correcting means corrects the valve in a direction of opening when the temperature of the catalytic layer is higher than a standard temperature, and corrects in the valve in a direction of closing when the temperature of the catalytic layer is lower than the standard temperature, and holds the valve with a fixed opening when the temperature of the catalytic layer is the same as the standard temperature.

14. An operation method of a hybrid fuel cell system, the hybrid fuel cell system constructed to supply electric power to an external load including a series circuit of a fuel cell and current restricting means for restricting an output current of the fuel cell to which a storage cell is connected, comprising the steps of:

detecting a fluctuation in the current demanded by the external load; and

changing the restriction of the output current of the fuel cell which is made by said current restricting means, with the passage of time.