Open LED Detection Controller for Fault-Tolerant Lighting Systems
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Solution Overview
Problem
LED lighting systems with multiple strings become inoperable due to overvoltage protection mechanisms when an open-circuit condition occurs in one string, leading to the disabling of the entire system, despite the need for fault-tolerant control to maintain operation.
Innovation Solution
A controller that detects open-string conditions and excludes the associated feedback signals from determining the minimum feedback voltage, allowing the system to continue operating by using a minimum voltage selector and control logic to identify and isolate open-circuit conditions, and employing an overvoltage warning mechanism to prevent false positives during transient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If overvoltage protection mechanism is implemented to protect circuits from excessive currents, then circuit safety is improved, but system reliability deteriorates when an open-circuit condition occurs in one LED string
Solution Approach 1:
The patent divides the LED lighting system into multiple independent LED strings that can operate independently. When one string experiences an open-circuit condition, the controller identifies this segment and isolates it from the feedback loop, allowing other strings to continue operating. This segmentation approach resolves the contradiction by enabling selective failure isolation rather than system-wide shutdown.
Solution Approach 2:
The patent implements differential treatment for different LED strings based on their operational status. Healthy strings contribute to feedback voltage regulation while open-circuit strings are excluded from feedback consideration. This local quality differentiation allows the system to maintain optimal performance in functional segments while accommodating failures in other segments without compromising overall system reliability.
2Measurement precision
If feedback mechanism is used to regulate drive voltage, then voltage regulation precision is improved, but system complexity increases due to additional detection and isolation logic
Solution Approach 1:
The patent enhances the existing feedback mechanism by adding open-circuit detection capability that monitors feedback voltages from each LED string. When an open-circuit condition is detected, the controller modifies the feedback loop to exclude the affected string. This extended feedback approach maintains voltage regulation precision while providing intelligent adaptation to system conditions, managing complexity through purposeful enhancement rather than fundamental redesign.
Data Source
AI summary
A fault-tolerant controller for a lighting system comprising: a plurality of light emitting diode (LED) circuits and a controllable power source to power the plurality of LED circuits. The controller comprising a minimum voltage selector to determine a minimum voltage from a plurality of feedback voltages, one feedback voltage for each of the plurality of LED circuits. A control logic to regulate the drive voltage for the LEDs; and an overvoltage warning mechanism to determine an overvoltage of the drive voltage. The controller identifies one or more open-circuit conditions, one for each LED circuit, for which the respective feedback voltage is below an open-circuit threshold, and which causes the minimum voltage selector to exclude one or more respective feedback voltages associated with the LED circuits which have an open-circuit condition.