Solid state relay and circuit breaker

• US 5,926,354 A
• Filed: 01/15/1998
• Issued: 07/20/1999
• Est. Priority Date: 06/11/1997
• Status: Expired due to Term

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: King, Ray J.
• Primary Examiner(s): Gaffin, Jeffrey
• Assistant Examiner(s): Jackson, Stephen W.
• Application Number:
  US09/007,627
• Time in Patent Office: 551 Days
• Field of Search: 361/88, 361/93, 361/100, 361/115, 361/23, 361/86, 361/101
• US Class Current: 361/93.4
• CPC Class Codes: H02H 3/087 for dc applications

Abstract

A current interruption circuit for interrupting current flow from a source of DC power to a load includes: an electronically controllable primary switch device adapted to be series coupled between the DC power source and the load, the primary switch device having a voltage thereacross which is proportional to a current flowing therethrough when biased in an on state. The circuit also includes a voltage sensing circuit adapted to sense the voltage across the primary switch device and produce a control signal in response thereto; and a gate drive circuit adapted to receive the control signal and bias the primary switch in an off state when the control signal indicates that the voltage across the primary switch has exceeded a predetermined value.

Claims

1. A current interruption circuit which functions as a resettable fuse for interrupting current flow from a single source of DC power to a load, the current interrupting circuit comprising:

a DC power source;

a load;

an electronically controllable primary switch device adapted to be series coupled between the DC power source and the load, the primary switch device having a voltage thereacross which is proportional to a current flowing therethrough when biased in an on state;

a voltage sensing circuit adapted to sense the voltage across the primary switch device and produce a control signal in response thereto; and

a gate drive circuit adapted to receive the control signal and bias the primary switch in an off state when the control signal indicates that the voltage across the primary switch has exceeded a predetermined value,

wherein the DC power source consists of a sole power source in the entire current interruption circuit.

2. The current interruption circuit of claim 1, wherein the gate drive circuit includes a control terminal, the gate drive circuit being enabled to turn on the primary switching device only when the control terminal is coupled to a first predetermined voltage level.

3. The current interruption circuit of claim 2, wherein the voltage sensing circuit and the gate drive circuit are adapted to latch the primary switching device in the off state after the voltage across the primary switch has exceeded the predetermined value.

4. The current interruption circuit of claim 3, wherein the voltage sensing circuit and the gate drive circuit are adapted to permit the primary switching device to enter the on state when the control terminal is released from the first predetermined level, coupled to a second predetermined voltage level, and again coupled to the first predetermined voltage level.

5. The current interruption circuit of claim 4, further including a reset circuit operatively coupled to the control terminal, the reset circuit being adapted to couple the control terminal to the first and second predetermined voltage levels.

6. The current interruption circuit of claim 4, further including a reset circuit operatively coupled to the control terminal, the reset circuit being adapted to couple the control terminal to the first and second predetermined voltage levels in response to an electronic control operating under a control program.

7. The current interruption circuit of claim 4, further including a reset circuit operatively coupled to the control terminal, the reset circuit being adapted to couple the control terminal to the first and second predetermined voltage levels in response to a human operator.

8. The current interruption circuit of claim 2, wherein the primary switching device is a P-channel MOSFET, a source of the MOSFET being operatively coupled toward the DC source and a drain of the MOSFET being operatively coupled toward the load.

9. The current interruption circuit of claim 8, wherein the voltage sensing circuit includes a PNP transistor, a base of the PNP transistor being operatively coupled to the drain of the MOSFET, an emitter of the PNP transistor being operatively coupled to the source of the MOSFET, and a collector of the PNP transistor providing the control signal to the gate drive circuit.

10. The current interruption circuit of claim 8, wherein the gate drive circuit includes a charging capacitor coupled at one end to the control terminal and at another end to the gate of the MOSFET such that the gate is biased below the source when the control terminal is coupled to the first predetermined voltage level.

11. The current interruption circuit of claim 10, wherein the charging capacitor has a value substantially greater than a gate-to-source capacitance of the MOSFET.

12. The current interruption circuit of claim 10, wherein the gate drive circuit including at least two series coupled impedances connected in parallel with the charging capacitor, the impedances maintaining the gate potential substantially below the source potential when the control terminal is coupled to the first predetermined voltage level and the control signal indicates that the voltage across the MOSFET is below the predetermined value.

13. The current interruption circuit of claim 12, wherein the impedances are resistors, the voltage sensing circuit includes a PNP transistor, a base of the PNP transistor is operatively coupled to the drain of the MOSFET, an emitter of the PNP transistor is operatively coupled to the source of the MOSFET, and a collector of the PNP transistor provides the control signal to the junction of the resistors.