Fuel cell system capable of reducing electric power loss

• US 6,255,008 B1
• Filed: 07/14/1999
• Issued: 07/03/2001
• Est. Priority Date: 07/16/1998
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Iwase, Masayoshi
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US09/353,439
• Time in Patent Office: 720 Days
• Field of Search: 429/9, 429/22, 429/23, 180/65.3
• US Class Current: 429/9
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 58/30 for monitoring or controlling fuel cells
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A fuel cell system minimizes the power loss that may occur in a conduction passage during supply of electric power from a fuel cell to a load. A bypass connects between the input of a DC/DC converter and the output thereof, and therefore supplies power generated by the fuel cell to an inverter, bypassing the DC/DC converter. A changeover switch selectively changes the connection of the output of the fuel cell between the connection to the input of the DC/DC converter and the connection to the bypass. When the fuel cell is connected to the DC/DC converter, the power from the fuel cell is supplied to the inverter or a battery via the DC/DC converter. When the fuel cell is connected to the bypass, the power from the fuel cell is supplied to the inverter, bypassing the DC/DC converter. A cutoff switch disconnects the output of the battery from a connecting line. That is, the cutoff switch disconnects the battery from the inverter, the bypass and the like when turned off. When turned on, the cutoff switch 41 connects the battery to those components.

Claims

1. A fuel cell system comprising:

a fuel cell adapted to be supplied with a fuel;

a secondary battery connected for storing power generated by the fuel cell and connected for supplying a power stored therein to a load;

a voltage adjuster capable of adjusting a voltage of the power generated by the fuel cell;

a first electric passage that supplies the power generated by the fuel cell to the load via the voltage adjuster;

a second electric passage that supplies the power generated by the fuel cell to the load without conduction via the voltage adjuster; and

a first switch that selectively switches a power connection path from the fuel cell to the load between the first electric passage and the second electric passage.

2. The fuel cell system according to claim 1, wherein the voltage adjuster is a DC/DC converter.

3. The fuel cell system according to claim 1, further comprising:

a second switch positioned to selectively disconnect an electric connection between the secondary battery and the voltage adjuster and an electric connection between the secondary battery and the load; and

a controller connected to the first and second switches to control the second switch to disconnect the electrical connection when at least one of a condition for elimination of a need to store a power into the secondary battery and a condition for elimination of a need to output a power from the secondary battery is established, and to control the first switch to select the first electric passage when the second switch disconnects the electric connection.

4. The fuel cell system according to claim 3, wherein the voltage adjuster is a DC/DC converter.

5. The fuel cell system according to claim 3, wherein a condition for the second switch to discontinue the electric connection between the secondary battery and the voltage adjuster and the electric connection between the secondary battery and the load is one of a condition that an amount of charge of the secondary battery is substantially 100%, and a condition that a difference between a required power of the load and an expected output power of the fuel cell is substantially zero and that the amount of charge of the secondary battery is greater than a predetermined reference amount.

6. The fuel cell system according to claim 5, wherein the voltage adjuster is a DC/DC converter.

7. An electric vehicle including a fuel cell system, comprising:

a fuel cell adapted to be supplied with a fuel;

a secondary battery connected for storing power generated by the fuel cell and connected for supplying a power stored therein to a load;

a voltage adjuster capable of adjusting a voltage of the power generated by the fuel cell;

a first electric passage that supplies the power generated by the fuel cell to the load via the voltage adjuster;

a second electric passage that supplies the power generated by the fuel cell to the load without conduction via the voltage adjuster; and

a first switch that selectively switches a power connection path from the fuel cell to the load between the first electric passage and the second electric passage.

8. The electric vehicle according to claim 7, wherein the voltage adjuster is a DC/DC converter.

9. The electric vehicle according to claim 7, further comprising:

a second switch positioned to selectively disconnect an electric connection between the secondary battery and the voltage adjuster and an electric connection between the secondary battery and the load; and

a controller connected to the first and second switches to control the second switch to disconnect the electrical connection when at least one of a condition for elimination of a need to store a power into the secondary battery and a condition for elimination of a need to output a power from the secondary battery is established, and to control the first switch to select the first electric passage when the second switch disconnects the electric connection.

10. The electric vehicle according to claim 9, wherein the voltage adjuster is a DC/DC converter.

11. The electric vehicle according to claim 9, wherein a condition for the second switch to discontinue the electric connection between the secondary battery and the voltage adjuster and the electric connection between the secondary battery and the load is one of a condition that an amount of charge of the secondary battery is substantially 100%, and a condition that a difference between a required power of the load and an expected output power of the fuel cell is substantially zero and that the amount of charge of the secondary battery is greater than a predetermined reference amount.

12. The electric vehicle according to claim 11, wherein the voltage adjuster is a DC/DC converter.

13. A fuel cell system comprising:

a fuel cell adapted to be supplied with a fuel;

secondary battery means for storing power generated by the fuel cell and for supplying a power stored therein to a load;

voltage adjuster means for adjusting a voltage of the power generated by the fuel cell;

first electric passage means for supplying the power generated by the fuel cell to the load via the voltage adjuster means;

second electric passage means for supplying the power generated by the fuel cell to the load without conduction via the voltage adjuster means; and

first switch means for selectively switching a power connection path from the fuel cell to the load between the first electric passage means and the second electric passage means.

14. The fuel cell system according to claim 13, wherein the voltage adjuster means is a DC/DC converter.

15. The fuel cell system according to claim 13, further comprising:

second switch means for selectively disconnecting an electric connection between the secondary battery means and the voltage adjuster means and an electric connection between the secondary battery means and the load; and

controller means for controlling the second switch means to disconnect the electrical connection when at least one of a condition for elimination of a need to store a power into the secondary battery means and a condition for elimination of a need to output a power from the secondary battery means is established, and for controlling the first switch means to select the first electric passage means when the second switch means disconnects the electric connection.

16. The fuel cell system according to claim 15, wherein the voltage adjuster means is a DC/DC converter.

17. The fuel cell system according to claim 15, wherein a condition for the second switch means to discontinue the electric connection between the secondary battery means and the voltage adjuster means and the electric connection between the secondary battery means and the load is one of a condition that an amount of charge of the secondary battery means is substantially 100%, and a condition that a difference between a required power of the load and an expected output power of the fuel cell is substantially zero and that the amount of charge of the secondary battery means is greater than a predetermined reference amount.

18. The fuel cell system according to claim 17, wherein the voltage adjuster means is a DC/DC converter.