초록 ▼

As disclosed, there is provided a small-size power system for fuel cell allowing efficient extraction of electric power-output from a fuel cell and a secondary cell, electronic equipment, and an electric power feeding method. The power system for fuel cell has a voltage conversion circuit and a rect

As disclosed, there is provided a small-size power system for fuel cell allowing efficient extraction of electric power-output from a fuel cell and a secondary cell, electronic equipment, and an electric power feeding method. The power system for fuel cell has a voltage conversion circuit and a rectification circuit, and is structured such that output voltage of the fuel cell is converted with a set voltage, which is an output voltage corresponding to a maximum electric power-output of the fuel cell, as a reference to produce a switch voltage, and at least either the switch voltage or an output voltage of the secondary cell is outputted through the rectification circuit. This allows parallel operation of the fuel cell and secondary cell in a state that the electric power of the fuel cell can be utilized to the full.

대표청구항 ▼

What is claimed is: 1. A fuel cell power system, comprising: a fuel cell configured to generate a first electric power; a secondary cell configured to output a secondary electric power; and a fuel cell controller connected to an output of the fuel cell and configured to compare a level of a fuel ce

What is claimed is: 1. A fuel cell power system, comprising: a fuel cell configured to generate a first electric power; a secondary cell configured to output a secondary electric power; and a fuel cell controller connected to an output of the fuel cell and configured to compare a level of a fuel cell output voltage with a first predetermined value and with a second predetermined value and to prevent the fuel cell from generating power when the level of the fuel cell output voltage is not more than the first predetermined value and to determine an output of the fuel cell and of the secondary cell based on the comparison of the level of the fuel cell output voltage with the second predetermined value. 2. The fuel cell power system according to claim 1, further comprising: a rectification circuit connected to receive the output of the fuel cell control circuit and an output of the secondary cell, the rectification circuit configured to control an output of the first electric power and the second electric power, wherein the rectification circuit outputs the first electric power when the level of the fuel cell output voltage is greater than a level of the secondary cell output voltage, outputs the first electric power and the second electric power when the level of the fuel cell output voltage is substantially equal to the level of the secondary cell output voltage, and outputs the second electric power when the level of the fuel cell output voltage is less than the level of the secondary cell output voltage. 3. The fuel cell power system according to claim 2, wherein during a period from when the fuel cell output voltage attains the first predetermined value until a time before the fuel cell output voltage attains a breakdown voltage, the fuel cell controller lowers the fuel cell output voltage to at least a discharge voltage of the secondary cell. 4. The fuel cell power system according to claim 2, wherein the rectification circuit is formed from diodes. 5. The fuel cell power system according to claim 1, wherein the first predetermined value corresponds to the fuel cell output voltage when a maximum electric power is output from the fuel cell. 6. The fuel cell power system according to claim 1, wherein the fuel cell controller sets the first predetermined value by converting the fuel cell output voltage to a voltage greater than a maximum output voltage of the secondary cell. 7. The fuel cell power system according to claim 1, wherein the fuel cell controller comprises: a voltage detection circuit configured to detect the fuel cell output voltage; a voltage setting circuit configured to set the second predetermined value; and a feedback section configured to apply feedback to a voltage outputted from the voltage setting circuit. 8. The fuel cell power system according to claim 7, wherein the voltage setting circuit sets the fuel cell output voltage to a voltage corresponding to the second predetermined value by the feedback section when the voltage detection circuit detects the fuel cell output voltage that is higher than the first predetermined value. 9. The fuel cell power system according to claim 7, wherein the voltage setting circuit terminates the output of the fuel cell when the voltage detection circuit detects that the fuel cell output voltage has attained the first predetermined value. 10. The fuel cell power system according to claim 1, further comprising a charge circuit connected to the fuel cell and the secondary cell and is configured to charge the secondary cell. 11. The fuel cell power system according to claim 10, wherein the charge circuit comprises: an output voltage comparator circuit connected to the output of the fuel cell and the output of the secondary cell, and is configured to compare the output voltage of the fuel cell and the first predetermined value and compare the output voltage of the secondary cell and a chargeable voltage value of the secondary cell; and a switch circuit connected between the output of the fuel cell and the secondary cell and is configured to apply the fuel cell output voltage to the secondary cell to charge the secondary cell. 12. The fuel cell power system according to claim 11, wherein the switch circuit applies the output voltage to the secondary cell when the output voltage comparator circuit detects that the fuel cell output voltage is greater than the first predetermined value and that the output voltage of the secondary cell has attained the chargeable voltage value. 13. The fuel cell power system according to claim 11, wherein the output voltage comparator circuit is further configured to detect a charge termination voltage after the switch circuit applies the fuel cell output voltage to the secondary cell. 14. The fuel cell power system according to claim 13, wherein the charge termination voltage is set to a value higher than the first predetermined value. 15. The fuel cell power system according to claim 13, wherein the switch circuit terminates the output of the fuel cell output voltage to the secondary cell when the output voltage comparator circuit detects the charge termination voltage. 16. The fuel cell power system according to claim 1, further comprising: an output termination circuit connected to the output of the secondary cell and capable of being connected to a load and is configured to determine when the output voltage of the secondary cell is lower than a load termination voltage. 17. The fuel cell power system according to claim 16, wherein the load termination voltage is set to a value higher than a final discharge voltage of the secondary cell. 18. The fuel cell power system according to claim 16, wherein the output termination circuit is configured to terminate output from the secondary cell when the load termination voltage is detected. 19. Electronic equipment powered by a fuel cell system comprising: a fuel cell power system; and a load configured to receive first electric power and second electric power fed from the fuel cell power system, wherein the fuel cell power system includes: a fuel cell configured to generate a first electric power; a secondary cell configured to output a secondary electric power; a fuel cell controller connected to an output of the fuel cell and configured to compare a level of a fuel cell output voltage with a first predetermined value and with a second predetermined value and to prevent the fuel cell from generating power when the level of the fuel cell output voltage is not more than the first predetermined value and and to determine an output of the fuel cell and of the secondary cell based on the comparison of the level of the fuel cell output voltage with the second predetermined value. 20. An electric power feeding method in a fuel cell power system for fuel cell having a fuel cell configured to generate first electric power and a secondary cell configured to output second electric power, the method comprising the steps of: (a) setting a first predetermined value; (b) setting a second predetermined value; (c) comparing a fuel cell output voltage with the first predetermined value and with the second predetermined value; (d) preventing the fuel cell from generating power when the fuel cell output voltage is not more than the first predetermined value; (e) determining an output of the first electric power and the second electric power by comparing the fuel cell output voltage with the second predetermined value. 21. A fuel cell power system, comprising: a fuel cell configured to generate a first electric power; a secondary cell configured to output a secondary electric power; and fuel cell controlling means for comparing a level of a fuel cell output voltage with a first predetermined value and with a second predetermined value for preventing the fuel cell from generating power when the level of the fuel cell output voltage is not more than the first predetermined value and for determining an output of the fuel cell and of the secondary cell based on the comparison of the level of the fuel cell output voltage with the second predetermined value. 22. The fuel cell power system according to claim 21, further comprising: rectification means for controlling an output of the first electric power and the second electric power, wherein the rectification means outputs the first electric power when the level of the fuel cell output voltage is greater than a level of the secondary cell output voltage, outputs the first electric power and the second electric power when the level of the fuel cell output voltage is substantially equal to the level of the secondary cell output voltage, and outputs the second electric power when the level of the fuel cell output voltage is less than the level of the secondary cell output voltage. 23. The fuel cell power system according to claim 22, wherein during a period from when the fuel cell output voltage attains the first predetermined value to a moment before the fuel cell output voltage attains a breakdown voltage, the fuel cell controlling means lowers the fuel cell output voltage to at least a discharge voltage of the secondary cell. 24. The fuel cell power system according to claim 21, wherein the first predetermined value corresponds to the fuel cell output voltage when a maximum electric power is output from the fuel cell. 25. The fuel cell power system according to claim 21, wherein the fuel cell controlling means sets the first predetermined value by converting the fuel cell output voltage to a voltage greater than a maximum output voltage of the secondary cell. 26. The fuel cell power system according to claim 21, wherein the fuel cell controller comprises: voltage detection means detecting the fuel cell output voltage; voltage setting means for setting the second predetermined value; and feedback means applying feedback to a voltage outputted from the voltage setting circuit. 27. The fuel cell power system according to claim 26, wherein the voltage setting means sets the fuel cell output voltage to a voltage corresponding to the second predetermined value by the feedback means when the voltage detection circuit detects the fuel cell output voltage that is higher than the first predetermined value. 28. The fuel cell power system according to claim 26, wherein the voltage setting means terminates the output of the fuel cell when the voltage detection means detects that the fuel cell output voltage has attained the first predetermined value. 29. The fuel cell power system according to claim 21, wherein the rectification means is formed from diodes. 30. The fuel cell power system according to claim 21, further comprising charge means for charging the secondary cell. 31. The fuel cell power system according to claim 30, wherein the charge means comprises: output voltage comparison means for comparing the fuel cell output voltage and the first predetermined value and for comparing the output voltage of the secondary cell and a chargeable voltage value of the secondary cell; and switching means for applying the fuel cell output voltage to the secondary cell to charging the secondary cell. 32. The fuel cell power system according to claim 31, wherein the switching means applies the output voltage to the secondary cell when the output voltage comparison means determines that the fuel cell output voltage is greater than the first predetermined value and that the output voltage of the secondary cell has attained the chargeable voltage value. 33. The fuel cell power system according to claim 31, wherein the output voltage comparison means is further configured for detecting a charge termination voltage after the switching means applies the fuel cell output voltage to the secondary cell. 34. The fuel cell power system according to claim 33, wherein the charge termination voltage is set to a value higher than the first predetermined value. 35. The fuel cell power system according to claim 33, wherein the switching means terminates the output of the fuel cell output voltage to the secondary cell when the output voltage comparison means detects the charge termination voltage. 36. The fuel cell power system according to claim 31, further comprising: an output termination means for determining when the output voltage of the secondary cell is lower than a load termination voltage. 37. The fuel cell power system according to claim 36, wherein the load termination voltage is set to a value higher than a final discharge voltage of the secondary cell. 38. The fuel cell power system according to claim 36, wherein the output termination means terminates the output from the secondary cell when the load termination voltage is detected.