NON-INTRUSIVE SHORT-CIRCUIT PROTECTION FOR POWER SUPPLY DEVICES

• US 20170310099A1
• Filed: 04/21/2016
• Published: 10/26/2017
• Est. Priority Date: 04/21/2016
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Inventors: Mirsky, Gregory, Sparling, Larry A., Klister, Jonathan T.
• Granted Patent: US 10,193,326 B2
• Time in Patent Office: Days
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02H 3/20 responsive to excess voltage
• CPC Class Codes: H02H 7/20 for electronic equipment for converters H02H7/10; for electric measuring instruments G01R1/36; for dc voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08
• CPC Class Codes: H03K 17/165 by feedback from the output circuit to the control circuit
• CPC Class Codes: H03K 17/20 Modifications for resetting core switching units to a predetermined state
• CPC Class Codes: H03K 5/04 by increasing duration; by decreasing duration
• CPC Class Codes: H03K 5/2463 using diodes

Abstract

Non-ideal diodes have a non-zero resistance across a PN junction when the junction is forward biased. When a diode comprising a power supply has a voltage drop across the junction that exceeds a predetermined threshold, the threshold-exceeding voltage drop trips a comparator, the output of which controls a switch between a power supply and a load.

Claims

1. A method of protecting a power source, having an output voltage, from a short circuit, the method comprising:

providing to a first input of a voltage comparator, the power source voltage minus the voltage drop across a first, forward-biased, non-ideal diode carrying electric current from the power source to a load;

providing to a second input of the voltage comparator, the power source voltage minus the voltage drop across a second, forward-biased, non-ideal diode, which is also coupled to the power source and which carries a reference current, to a second input of a voltage comparator; and

providing a control voltage signal, which is output from the comparator, to a switching device located between the power source and the first forward-biased non-ideal diode, the control voltage signal and switch being selected and configured to disconnect the power source when the power supply voltage drop across the first forward-biased, non-ideal diode exceeds a predetermined threshold relative to the power supply voltage drop across the second forward-biased, non-ideal diode.

2. The method of claim 1, wherein the second, forward-biased, non-ideal diode serves for thermal compensation of the voltage drop across the first, forward-biased, non-ideal diode carrying electric current from the power source to a load.

3. The method of claim 1, wherein the power source is a source of direct current having a non-zero output voltage greater than zero volts.

4. The method of claim 1, wherein the switching device is a transistor.

5. The method of claim 1, wherein first and second non-ideal diodes each comprise a junction between an N-type semiconductor material and a P-type semiconductor material and wherein the junction has a non-zero resistance when it is forward biased.

6. The method of claim 4, wherein the non-zero resistance is non-linear.

7. A non-intrusive short circuit protection apparatus for a power supply device, the apparatus comprising:

a voltage comparator having first and second inputs and an output;

a first, non-ideal diode having an anode coupled to the power supply device and a cathode coupled to a load requiring electric current, the cathode being additionally coupled to the first input of the voltage comparator, the first non-ideal diode carrying the electric current required by the load;

a second, non-ideal diode having an anode coupled to the power supply device and a cathode coupled to the second input of the voltage comparator; and

a switching device having an input terminal, an output terminal and a control signal terminal, the switching device input terminal being coupled to the power source, the switching device output terminal being coupled to the anodes of both the first and second non-ideal diodes, the control signal terminal being coupled to the output of the voltage comparator;

wherein a voltage signal provided to the control signal terminal of the switching device from the output of the voltage comparator causes the switching device to disconnect the power source from the first diode when a difference between the first cathode voltage and the second cathode voltage exceeds a first, predetermined threshold.

8. The apparatus of claim 7, wherein the power supply device provides direct current and has a non-zero output voltage.

9. The apparatus of claim 7, wherein the power supply device comprises a motor vehicle battery.

10. The apparatus of claim 7, wherein the voltage signal provided to the control signal terminal of the switching device from the output of the voltage comparator also causes the switching device to disconnect the power source from the second diode when the difference between the first cathode voltage and the second cathode voltage exceeds the first, predetermined threshold.

11. The apparatus of claim 7, further comprising a first voltage divider having an input node, an output node and a reference potential node, the input node being coupled to the anode of the first diode, the reference potential node being coupled to a reference potential for the apparatus, the output node being coupled to the first input of the voltage comparator, the first voltage divider having an output voltage that is provided to the comparator and which determines an amount of current passing through the first diode at which the comparator turns off the switching device.

12. The apparatus of claim 11, further comprising a second voltage divider having an input node, an output node and a reference potential node, the input node of the second voltage divider being coupled to the anode of the second diode, the reference potential node being coupled to a reference potential for the apparatus, the output node being coupled to the second input of the voltage comparator, the second voltage divider having an output voltage that is provided to the comparator and which determines an amount of current passing through the first diode at which the comparator turns off the switching device.

13. The apparatus of claim 12, further comprising a capacitor coupled across a resistor comprising the second voltage divider.

14. The apparatus of claim 7, wherein the switching device is a transistor.

15. The apparatus of claim 7, wherein the comparator comprises a processor.

16. The apparatus of claim 7, wherein diodes have a non-linear, non-zero direct-current resistance when they are forward biased.