Self-healing overtemp circuit for LED lighting thermal runaway
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Solution Overview
Problem
Current LED lighting systems for wide area and sports applications lack effective high-voltage overtemp circuits to detect thermal runaway events and safely manage power restoration without requiring part replacement, leading to potential component damage and inefficiency.
Innovation Solution
A self-healing overtemp circuit that includes temperature, current, and voltage sensing circuits, along with a processor to detect thermal runaway events, reduce power to LEDs, and automatically reestablish power when conditions are safe, using solid-state components to prevent damage from excess voltage and current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional overtemp circuits with thermal fuses are used, then thermal runaway events can be detected and power can be terminated, but the circuit requires part replacement before power can be restored
Solution Approach 1:
The overtemp circuit automatically restores power after a thermal runaway event without requiring manual intervention or part replacement. The circuit monitors temperature, terminates power when thresholds are exceeded, and automatically reestablishes power when conditions return to normal, making the system self-healing and eliminating the need for thermal fuse replacement.
2Productivity
If power is immediately reestablished after thermal runaway event, then lighting can be restored quickly, but excess voltage and current can damage components
Solution Approach 1:
Before reestablishing full power to the LEDs, the circuit first cycles the driver off and on, and dissipates excess voltage through a resistor network. This preliminary action prevents dangerous voltage spikes and current surges that would otherwise damage the LEDs when power is restored after a thermal runaway event.
Solution Approach 2:
The circuit incorporates a resistor network that provides a safe discharge path for excess voltage stored in capacitors before power is reestablished to the LEDs. This cushioning mechanism absorbs and dissipates potentially damaging energy in advance, protecting components from voltage spikes during the power restoration process.
3Illumination intensity
If high voltage is used to power large numbers of LEDs, then adequate lighting for wide area applications can be achieved, but traditional overtemp circuit components cannot detect or respond to thermal events
Solution Approach 1:
The circuit replaces mechanical thermal fuse components with solid-state electronic sensing and control circuitry that can detect temperature conditions and control power termination and restoration. This electronic substitution enables reliable overtemp detection and automatic self-healing in high-voltage LED lighting systems where traditional mechanical thermal protection devices are ineffective.
Data Source
AI summary
A self-healing overtemp circuit is described and illustrated comprising a temperature sensing circuit, a voltage sensing circuit, and optionally, a current sensing circuit. A lower cost, simplified alternative overtemp circuit is also discussed. The self-healing overtemp circuit is designed to ramp down power in an LED lighting system (or other electrical circuit) in response to a sensed or impending thermal runaway (and optionally, overcurrent) event. Said thermal runaway and overcurrent events may be a result of failure of one or more components (e.g., driver, active cooling means) of the lighting system. The self-healing overtemp circuit further comprises means of restoring power to said LEDs in a manner that avoids (i) a perceivably bright flash of light or (ii) increased risk of component failure.