Short circuit detection for lighting circuits
First Claim
1. A fault-tolerant controller for a lighting system comprising a plurality of LED circuits and a controllable power source providing a drive voltage to power the plurality of LED circuits, the fault-tolerant controller comprising:
- a control unit configured to cause regulation of the drive voltage based on a determination of a plurality of feedback voltages, one feedback voltage for each of the plurality of LED circuits; and
a fault condition detecting means configured to identify one or more fault conditions from the plurality of feedback voltages, wherein at least one of the LED circuits is determined as a fault circuit having a fault condition for which the respective feedback voltage is below a first fault circuit condition threshold, wherein the fault condition detecting means is further configured, in response to a detected fault condition, to apply a test voltage to a cathode of the fault-circuit and, if the feedback voltage of the fault circuit remains below a second fault circuit condition threshold, the fault circuit is determined to have a short circuit condition, wherein the fault condition detecting means comprises a plurality of pull-up circuits, each pull-up circuit provided between ground voltage and a cathode for each LED circuit, wherein each pull-up circuit comprises a voltage source and a switch, the fault condition detecting means being configured to cause closing of the switch associated with the fault circuit upon detecting a fault condition to apply the test voltage to the cathode of the fault circuit.
1 Assignment
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Accused Products
Abstract
This invention relates to control circuits for LED systems with a feedback loop to regulate a drive voltage. A controller for the system is proposed comprising a plurality of LED circuits and a controllable power source. The controller comprises a control unit configured to cause regulation of the drive voltage based on a determination of a plurality of feedback voltages and a fault condition detecting means. At least one of the LED circuits is determined as having a fault condition if the respective feedback voltage is below a fault threshold. In response to a detected fault condition, a test voltage is applied to a cathode of the fault circuit to confirm the presence of a fault condition.
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Citations
13 Claims
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1. A fault-tolerant controller for a lighting system comprising a plurality of LED circuits and a controllable power source providing a drive voltage to power the plurality of LED circuits, the fault-tolerant controller comprising:
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a control unit configured to cause regulation of the drive voltage based on a determination of a plurality of feedback voltages, one feedback voltage for each of the plurality of LED circuits; and a fault condition detecting means configured to identify one or more fault conditions from the plurality of feedback voltages, wherein at least one of the LED circuits is determined as a fault circuit having a fault condition for which the respective feedback voltage is below a first fault circuit condition threshold, wherein the fault condition detecting means is further configured, in response to a detected fault condition, to apply a test voltage to a cathode of the fault-circuit and, if the feedback voltage of the fault circuit remains below a second fault circuit condition threshold, the fault circuit is determined to have a short circuit condition, wherein the fault condition detecting means comprises a plurality of pull-up circuits, each pull-up circuit provided between ground voltage and a cathode for each LED circuit, wherein each pull-up circuit comprises a voltage source and a switch, the fault condition detecting means being configured to cause closing of the switch associated with the fault circuit upon detecting a fault condition to apply the test voltage to the cathode of the fault circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of detecting a fault condition within a plurality of LED circuits of a lighting system comprising the steps of:
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determining a feedback voltage for each of the LED circuits of the plurality of LED circuits; causing regulation of a drive voltage to power the plurality of LED circuits based on the plurality of feedback voltages; determining a fault circuit having a fault condition among the plurality of LED circuits for which the respective feedback voltage of the respective LED circuit is below a first fault condition threshold; in response to the detected fault condition, applying a test voltage from a pull-up circuit comprising a voltage source and a switch to a cathode of the determined fault circuit having a fault condition; and if the feedback voltage of the determined fault circuit remains below a second fault circuit condition threshold, determining the fault circuit as having a short circuit condition, wherein applying the test voltage includes closing the switch associated with the fault circuit to apply the test voltage to the cathode of the fault circuit. - View Dependent Claims (11, 12)
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13. A lighting system comprising:
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a plurality of LED circuits; a controllable power source; and a fault-tolerant controller for a lighting system comprising a plurality of LED circuits and a controllable power source providing a drive voltage to power the plurality of LED circuits wherein the controller is configured to detecting LED short circuits and/or LED open circuits, the controller comprising; a fault condition detecting means configured to identify one or more fault conditions from the plurality of feedback voltages, wherein at least one of the LED circuits is determined as a fault circuit having a fault condition for which the respective feedback voltage is below a first fault circuit condition threshold, wherein the fault condition detecting means is further configured, in response to a detected fault condition, to apply a test voltage to a cathode of the fault circuit and, if the feedback voltage of the fault circuit remains below a second fault circuit condition threshold, the fault circuit is determined to have a short circuit condition, wherein the fault condition detecting means comprises a plurality of pull-up circuits, each pull-up circuit provided between ground voltage and a cathode for each LED circuit, wherein each pull-up circuit comprises a voltage source and a switch, the fault condition detecting means being configured to cause closing of the switch associated with the fault circuit upon detecting a fault condition to apply the test voltage to the cathode of the fault circuit.
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Specification