Fault-Tolerant Controller for LED Lighting Short Circuit Detection
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Solution Overview
Problem
LED lighting systems face issues with short circuit and open circuit conditions, leading to uncontrollable current boosts and potential damage, as existing feedback mechanisms fail to distinguish between these conditions, causing the entire system to become inoperable when an open circuit occurs in one string.
Innovation Solution
A fault-tolerant controller is introduced, capable of detecting short circuits and open circuits by applying a test voltage and using comparators and logic gates to differentiate between the two conditions, allowing the system to continue operating by excluding affected strings from the voltage feedback mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback mechanism is used to regulate drive voltage, then voltage regulation is improved, but the system cannot distinguish between short circuit and open circuit conditions, leading to system failure
Solution Approach 1:
The patent segments the fault detection process into distinct phases: initial feedback-based voltage regulation, fault condition triggering, and test voltage application phase. This segmentation allows the system to switch between different operational modes depending on the detected condition, enabling both voltage regulation and fault differentiation without compromise
Solution Approach 2:
The patent applies preliminary action by pre-configuring test voltage sources and detection circuits that remain dormant during normal operation. When a fault condition is detected, these pre-prepared components are activated to perform differentiation between short circuit and open circuit conditions, avoiding the need for complex real-time decision-making during fault events
2Productivity
If the system continues operation after a fault, then productivity is maintained, but faulty strings may cause system-wide damage
Solution Approach 1:
The patent extracts faulty LED strings from the operational system by identifying and isolating them through test voltage application. Once a string is determined to be faulty (short circuit or open circuit), it is excluded from further operation, allowing the remaining healthy strings to continue operating without risk of damage from the faulty component
Solution Approach 2:
The patent converts the harmful fault condition into a beneficial detection opportunity. By applying test voltage when a fault is detected, the system not only identifies the nature of the fault (short circuit vs. open circuit) but also locates the specific faulty string, transforming a potentially damaging event into useful diagnostic information that enables selective isolation of the problem area
3Measurement precision
If test voltage is applied to detect short circuit, then detection accuracy is improved, but additional circuit complexity is introduced
Solution Approach 1:
The patent implements multi-functionality by designing the test voltage application circuit to serve multiple purposes: it differentiates between short circuit and open circuit conditions, locates faulty LED strings, and provides diagnostic information. This single test mechanism handles multiple detection tasks that would otherwise require separate circuits, reducing overall system complexity while maintaining high detection accuracy
Solution Approach 2:
The patent employs feedback by monitoring the response of the LED string to the applied test voltage. The feedback signal from the voltage divider and comparison circuit indicates whether the string has a short circuit, open circuit, or is functioning normally. This feedback mechanism enables accurate fault detection without requiring complex direct measurement circuits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The controller effectively prevents damage by disabling faulty LED strings, ensuring the remaining strings can operate safely and reducing the risk of system-wide failure due to open circuit conditions.
Implementation Method 1
A LED circuit is determined as a fault circuit having a fault condition if its respective feedback voltage is below a first fault-circuit condition threshold. 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.
Data Source
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AI summary
This application relates to control circuits for lighting systems. In particular, it relates to control circuits for LED lighting systems with a feedback loop to regulate a drive voltage for the lighting system. A fault-tolerant controller (405) for a lighting system (400) is proposed comprising a plurality of light emitting diode "LED" circuits (401-1, 401-N) and a controllable power source (403) providing a drive voltage (404) to power the plurality of LED circuits (401-1, 401-N). The controller (405) comprises: a control unit (409) configured to cause regulation of said drive voltage (404) based on a determination of a plurality of feedback voltages (402-1, 402-N), one feedback voltage (402-1, 402-N) for each of the plurality of LED circuits (401-1, 401-N); a fault condition detecting means configured to identify one or more fault conditions from the plurality of feedback voltages (402-1, 402-N), wherein at least one of the LED circuits (401-1, 401-N) is determined as a fault circuit having a fault condition for which the respective feedback voltage (402-1, 402-N) is below a first fault-circuit condition threshold (493), 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 (493), the fault circuit is determined to have a short circuit condition and otherwise and open-circuit condition.