SECONDARY PROTECTION APPROACH FOR POWER SWITCHING APPLICATIONS

• US 20080259914A1
• Filed: 04/17/2007
• Published: 10/23/2008
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Simper, Norbert J., Bach, Martin
• Granted Patent: US 8,390,972 B2
• Time in Patent Office: Days
• US Class Current: 370/388
• CPC Class Codes: H02H 3/05 with means for increasing reliability, e.g. redundancy arrangements for logic circuits H03K19/003
• CPC Class Codes: H02H 3/087 for dc applications

Abstract

An apparatus and method for providing a primary and a secondary protection to a load in a power switching application uses an electronic circuit breaker to selectively permit a flow of current from an input to a load. The circuit breaker comprises a plurality of first switches coupled in parallel, and a plurality of fuses coupled to the plurality of first switches. In a disclosed embodiment, each first switch is coupled to a first fuse and to a second fuse. A controller opens and closes the plurality of first switches by commanding a driver current ON and OFF. The controller is operable to detect a fault condition and to open the plurality of first switches in response to the fault condition by commanding the driver current OFF. If the controller fails to open one of the first switches, one of the fuses coupled to the switch is operable to blow. In addition, the circuit breaker also comprises a charge pump that provides an electric current to a second plurality of switches to prevent the second plurality of switches form shorting the driver current.

Claims

1. An electronic system for providing power to a load, comprising:

a plurality of first switches;

a plurality of fuses, wherein each switch is coupled to at least one fuse; and

a controller, wherein the controller is operable to detect a fault condition and to open the plurality of first switches in response to the fault condition, and wherein if the controller fails to open one of the plurality of first switches, a fuse associated with the one first switch is operable to blow.

2. The system of claim 1, wherein each first switch is coupled to a first fuse and to a second fuse.

3. The system of claim 2, wherein each first fuse is coupled to an input of a first switch, and each second fuse is coupled to a control input of a first switch.

4. The system of claim 3, wherein the first fuse is operable to blow if an input of a first switch is shorted to an output of a first switch.

5. The system of claim 2, wherein the second fuse is operable to blow if a control input of a first switch is coupled to an input of a first switch.

6. The system of claim 1, wherein each of the plurality of first switches is a MOSFET.

7. The system of claim 1, further comprising:

a driver that provides a driver current to selectively turn the plurality of first switches ON and OFF; and

a charge pump that provides a charge pump current to a second plurality of switches to prevent the second plurality of switches from shorting the driver current, wherein the driver and the charge pump are operated by the controller.

8. The system of claim 7, wherein the second plurality of switches comprises a first switch and a second switch, and an output of the first switch is coupled to a control input of the second switch.

9. The system of claim 8, wherein the first switch is a JFET and the second switch is a transistor.

10. The system of claim 8, wherein the driver amplifies a driver input voltage to provide a driver output voltage that is greater than the driver input voltage, and wherein the driver output voltage is coupled to the control input of each of the plurality of first switches to provide the driver current.

11. The system of claim 1, wherein the load is a component on an aircraft.

21. The system of claim 1, wherein each of the plurality of fuses comprises a bond wire specifically sized and constructed to provide a required fusing characteristic.

12. A method of providing fault protection, comprising the steps of:

detecting a fault condition;

opening a plurality of first switches in response to the fault condition;

coupling at least one fuse to each of the plurality of first switches, wherein the at least one fuse is operable to blow if its coupled switch fails to open.

13. The method of claim 12, wherein the step of detecting a fault condition comprises:

measuring a current;

determining if the current exceeds a current threshold.

14. The method of claim 12, wherein the step of opening a plurality of first switches in response to the fault condition further comprises commanding a driver current OFF, wherein the driver current is coupled to a control input of each of the plurality of first switches.

15. The method of claim 14, wherein the step of opening a plurality of first switches in response to the fault condition further comprises the step of commanding a charge pump OFF, wherein turning the charge pump OFF couples the driver current to a ground connection.

16. The method of claim 12, wherein the step of coupling at least one fuse to the plurality of first switches comprises coupling a first fuse to an input a first switch.

17. The method of claim 12, wherein the step of coupling at least one fuse to the plurality of first switches comprises coupling a second fuse to control input a first switch.

18. An electric system for use on a vehicle comprising:

a load;

a first input voltage; and

at least one circuit breaker, wherein the circuit breaker includes;

a plurality of first switches;

a plurality of fuses coupled to the plurality of first switches, wherein each first switch is coupled to a first fuse and a second fuse; and

a controller that is operable to detect a fault condition and to open the plurality of first switches in response to the fault condition, wherein the plurality of fuses are operable to blow if the controller fails to open one of the first switches, and wherein the circuit breaker selectively permits a flow of current from the first input voltage to the load.

19. The system of claim 18, wherein the vehicle is an aircraft.

20. The system of claim 18, further comprising:

a second input voltage, wherein the circuit breaker further includes;

a driver that provides a driver current to the plurality of first switches to selectively open and close the plurality of first switches, wherein the second input voltage is coupled to the driver; and

charge pump that provides a charge pump current to a second plurality of switches to prevent the second plurality of switches from shorting the first current, wherein the driver and the charge pump are operated by the controller.