SSL Power Limit Controller for Transient Fault Recovery
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Solution Overview
Problem
Solid state lighting (SSL) devices, such as LEDs and OLEDs, face challenges in managing power levels to prevent over-temperature and abnormal operation, particularly during fault conditions and ambient temperature variations, which can lead to increased impedance and potential fire hazards.
Innovation Solution
A system and method for monitoring and limiting power to SSL devices, which includes a power circuit, power limit, and power limit controller to reduce load power when it exceeds predetermined levels, allowing for a recovery mode instead of immediate shutdown, and configuring power limits within Class 2 power levels to address variability in electrical circuits and characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is immediately disconnected upon detecting over-power or over-current condition, then fire hazard risk is reduced, but transient fault conditions cause unnecessary shutdowns
Solution Approach 1:
The patent applies preliminary action by implementing a recovery mode that attempts to reduce output power and wait for a predetermined time before shutdown. This preliminary recovery attempt is made before permanent disconnection, allowing transient faults to self-correct without causing unnecessary system shutdowns while still protecting against genuine over-power conditions that could cause fire hazards.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a recovery mode with predetermined time delays and power reduction steps. This cushioning mechanism provides a buffer between detecting an over-power condition and executing permanent shutdown, allowing the system to recover from transient faults while maintaining protection against sustained hazardous conditions.
2Object-affected harmful factors
If power limit is set to UL1310 Class 2 level of 100 watts, then safety compliance is achieved, but cold start power requirements are not met
Solution Approach 1:
The patent applies dynamics by making the power limit adjustable rather than fixed. The power limit can be dynamically configured based on operating conditions, allowing it to exceed UL1310 Class 2 levels during cold start when higher power is needed for LED activation, then enforce the 100-watt limit during normal operation to maintain safety compliance.
Solution Approach 2:
The patent implements parameter changes by allowing the power limit parameter to be modified based on operational context. During cold start conditions, the power limit parameter can be temporarily increased to accommodate the higher inrush power requirements of LEDs, then returned to the compliant 100-watt level for sustained operation.
3Loss of energy
If output power is continually cycled on and off in over-power condition, then power dissipation is limited, but LED load experiences stress and reduced reliability
Solution Approach 1:
The patent applies preliminary action by first attempting to reduce the output power level before cycling it off completely. This preliminary power reduction maintains the LED load connection while limiting power dissipation, avoiding the stress and reliability degradation that would result from complete power cycling.
Solution Approach 2:
The patent implements continuity of useful action by maintaining the power connection to the LED load during over-power conditions through power reduction rather than complete disconnection. This continuous connection allows the LED to remain operational at reduced power levels, avoiding the reliability issues associated with repeated on-off cycling.
Data Source
AI summary
The disclosure is directed at a system, power supplied to a solid state lighting (SSL) device when an operational fault condition is sensed such as when the power level being supplied to the device is sensed to be meeting or higher than an expected or predetermined level. The system, method and apparatus provide a recovery aspect which means that the SSL device will not be automatically shut down (or power being supplied to the SSL device will not be immediately stopped) upon the discovery of the operational fault condition but will enter a recovery mode.