System and Method for Short-Circuit Detection in Load Chains

Patent metadata

Field	Value
Publication number	US-2016349304-A1
Application number	US-201514723182-A
Country	US
Kind code	A1
Filing date	May 27, 2015
Priority date	May 27, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

An embodiment method for short-circuit detection includes determining a set of local reference voltages each associated with a respective load chain in a plurality of load chains, and determining a global reference voltage in accordance with the set of local reference voltages. The method also includes determining, for each load chain in the plurality of load chains, a respective per-chain reference voltage in accordance with the global reference voltage, and comparing, for each load chain in the plurality of load chains, the respective per-chain reference voltage relative to a respective measured voltage across each load chain to determine a respective short-circuit condition.

First claim

What is claimed is:

1 . A method for short-circuit detection, the method comprising:
determining a set of local reference voltages each associated with a respective load chain in a plurality of load chains; determining a global reference voltage in accordance with the set of local reference voltages; determining, for each load chain in the plurality of load chains, a respective per-chain reference voltage in accordance with the global reference voltage; and comparing, for each load chain in the plurality of load chains, the respective per-chain reference voltage relative to a respective measured voltage across each load chain to determine a respective short-circuit condition.

2 . The method of claim 1 , wherein the determining the set of local reference voltages comprises:
determining, for each load chain in the plurality of load chains, a respective local reference voltage comprising a ratio of the respective measured voltage across each load chain divided by a respective number of electrical loads in each load chain.

3 . The method of claim 2 , wherein the electrical loads comprise light-emitting diodes.

4 . The method of claim 1 , wherein the determining the respective per-chain reference voltage for each load chain comprises multiplying the global reference voltage with a respective number of electrical loads in each load chain.

5 . The method of claim 1 , wherein the determining the global reference voltage comprises determining a maximum voltage of the set of local reference voltages.

6 . The method of claim 1 , wherein the determining the global reference voltage comprises calculating an average voltage of the set of local reference voltages.

7 . The method of claim 1 , wherein the determining the global reference voltage comprises:
excluding a maximum voltage and a minimum voltage of the set of local reference voltages to determine a subset of local reference voltages; and calculating an average voltage of the subset.

8 . The method of claim 1 , wherein the comparing the respective per-chain reference voltage comprises:
calculating a voltage difference of the respective measured voltage subtracted from the respective per-chain reference voltage; and determining the respective short-circuit condition such that a short circuit is detected when the voltage difference is greater than a threshold voltage and the short circuit is not detected otherwise.

9 . The method of claim 1 , further comprising storing the respective short-circuit condition in a storage device.

10 . A short-circuit detection circuit configured to:
determine a set of local reference voltages each associated with a respective load chain in a plurality of load chains; determine a global reference voltage in accordance with the set of local reference voltages; determine, for each load chain in the plurality of load chains, a respective per-chain reference voltage in accordance with the global reference voltage; and compare, for each load chain in the plurality of load chains, the respective per-chain reference voltage relative to a respective measured voltage across each load chain to determine a respective short-circuit condition.

11 . The short-circuit detection circuit of claim 10 , further configured to:
determine, for each load chain in the plurality of load chains, a respective local reference voltage in the set of local reference voltages, the respective local reference voltage comprising a ratio of the respective measured voltage across each load chain divided by a respective number of electrical loads in each load chain.

12 . The short-circuit detection circuit of claim 11 , wherein the electrical loads comprise light-emitting diodes.

13 . The short-circuit detection circuit of claim 10 , further configured to:
multiply the global reference voltage with a respective number of electrical loads in each load chain to determine the respective per-chain reference voltage for each load chain.

14 . The short-circuit detection circuit of claim 10 , wherein the global reference voltage comprises a maximum voltage of the set of local reference voltages.

15 . The short-circuit detection circuit of claim 10 , wherein the global reference voltage comprises an average voltage of the set of local reference voltages.

16 . The short-circuit detection circuit of claim 10 , further configured to:
exclude a maximum voltage and a minimum voltage of the set of local reference voltages to determine a subset of local reference voltages; and calculate an average voltage of the subset to determine the global reference voltage.

17 . The short-circuit detection circuit of claim 10 , further configured to:
calculate a voltage difference of the respective measured voltage subtracted from the respective per-chain reference voltage; and determine the respective short-circuit condition such that a short circuit is detected when the voltage difference is greater than a threshold voltage and the short circuit is not detected otherwise.

18 . The short-circuit detection circuit of claim 10 , further configured to store the respective short-circuit condition in a storage device.

19 . The short-circuit detection circuit of claim 10 , further comprising a processor configured to perform the steps of:
determining the set of local reference voltages; determining the global reference voltage; determining, for each load chain, the respective per-chain reference voltage; and determining, for each load chain, the respective short-circuit condition.

20 . A short-circuit detector comprising:
a plurality of voltage divider circuits each coupled to a respective chain of electrical loads; a reference determining circuit comprising a plurality of transistors coupled to the plurality of voltage divider circuits; a voltage multiplier coupled to the reference determining circuit; and a comparator.

21 . The short-circuit detector of claim 20 , further comprising a plurality of analog-to-digital converters coupled between the plurality of voltage divider circuits and a plurality of input terminals.

22 . The short-circuit detector of claim 20 , wherein each voltage divider circuit in the plurality of voltage divider circuits comprises a selectable voltage divider circuit comprising a plurality of selectable resistors.

23 . The short-circuit detector of claim 20 , wherein the reference determining circuit further comprises a plurality of non-inverting input terminals and an inverting input terminal, wherein:
a first set of transistors in the plurality of transistors is coupled to the plurality of non-inverting input terminals; and a second transistor in the plurality of transistors is coupled to the inverting input terminal.

24 . The short-circuit detector of claim 20 , wherein the voltage multiplier comprises:
a resistor matrix comprising at least one selectable resistor; a differential amplifier; and a voltage-to-current converter coupled between an output of the differential amplifier and the resistor matrix.

25 . The short-circuit detector of claim 20 , wherein the comparator comprises a window comparator.

26 . The short-circuit detector of claim 20 , wherein the plurality of voltage divider circuits, the reference determining circuit, the voltage multiplier, and the comparator are all disposed in a single integrated circuit.

Assignees

• Infineon Technologies Ag

Inventors

• Sartori Damiano
• Pamato Marco
• Galvano Maurizio

Classifications

• G01R31/50 Primary

  Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58) · CPC title

• H05B45/46

  having LEDs disposed in parallel lines · CPC title

• G01R31/2635

  Testing light-emitting diodes, laser diodes or photodiodes · CPC title

• B60Q11/005

  for lighting devices, e.g. indicating if lamps are burning or not · CPC title

• G01R31/025 Primary

  Physics · mapped topic