DC Thermal Protection Device for LED Luminaire Temperature Management
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Solution Overview
Problem
Thermal management in LED luminaires is challenging due to insulation preventing necessary airflow, and existing thermal protection devices for DC power systems are either too large, expensive, or unsuitable for low power DC applications, failing to meet UL standards and efficiently manage temperature thresholds.
Innovation Solution
A thermal protection device with a housing that includes a heating circuit with series-connected resistors and a thermal switch, coupled with a thermal circuit breaker, which develops different heat magnitudes based on temperature and provides output DC power while interrupting it when a threshold is exceeded, ensuring safe operation and compliance with UL standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AC-rated thermal protection devices are used in DC power systems, then thermal protection function is provided, but the device size increases and cost increases
Solution Approach 1:
The patent changes the voltage parameter from AC to DC (60V DC maximum), enabling the use of smaller, DC-rated components instead of AC-rated components. This parameter change allows selection of appropriately sized DC thermal protection devices that meet UL standards without the excessive size and cost of AC-rated alternatives.
2Reliability
If AC-rated thermal protection devices are used in DC power systems, then thermal protection function is provided, but the device cost increases
Solution Approach 1:
The patent changes the voltage parameter from AC to DC (60V DC maximum), enabling the use of smaller, DC-rated components instead of AC-rated components. This parameter change allows selection of appropriately sized DC thermal protection devices that meet UL standards without the excessive size and cost of AC-rated alternatives.
3Volume of moving object
If standard DC thermal protection switches are used, then device size is reduced, but they cannot operate at voltages up to 60 VDC
Solution Approach 1:
The patent creates a universal thermal protection device that can operate across a wide voltage range (up to 60V DC) while maintaining compact size. The device integrates a DC-rated thermal switch, heating circuit, and bi-metal switch that work together to provide thermal protection functionality across the entire voltage range, making it adaptable to various DC-powered LED luminaire applications.
4Duration of action of stationary object
If thermal protection circuits are added to LED luminaires, then LED lifespan is extended through temperature control, but device complexity increases
Solution Approach 1:
The patent merges the thermal sensing function and thermal protection switching function into a single integrated circuit. The bi-metal switch serves dual purposes: it senses temperature through thermal contact with the heating circuit and simultaneously acts as the protection switch. This consolidation reduces component count and circuit complexity while maintaining effective thermal protection that extends LED lifespan.
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
Effectively manages temperature in LED luminaires by preventing over-temperature conditions, extending the lifespan of LEDs, and meeting UL safety requirements without relying on AC-rated components, using off-the-shelf UL-rated components to ensure reliable operation and compliance with safety standards.
Implementation Method 1
A heating circuit is coupled to the electrical input for developing one of first and second different heat magnitudes depending upon a temperature magnitude in the housing
Implementation Method 2
the use of low power DC can be problematic when designing a thermal protection circuit for the luminaire... A UL XAPX2/8 recognized thermal protection bi-metal switch
Data Source
AI summary
According to one aspect, a thermal protection device is provided having an electrical input for receiving input DC power and an electrical output for connection to a load. A heating circuit is coupled to the electrical input for developing one of first and second different heat magnitudes depending upon a temperature magnitude in the housing. An additional circuit is in thermal communication with the heating circuit for providing output DC power to the electrical output when the first heat magnitude is developed and for interrupting the output DC power when the second heat magnitude is developed.