LED Power Supply Thermal De-rating with Controlled Current Ramp
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Solution Overview
Problem
Conventional power supplies cause undesirable lighting artifacts like flickering when adjusting current to LED loads to reduce their temperature, as they provide immediate changes in current, which can lead to damage and an unpleasant user experience.
Innovation Solution
A power supply that detects over-temperature conditions in LEDs and adjusts the output current gradually, using a selected rate of change to reduce the temperature without causing noticeable changes in light emission, allowing for pre-programmed or user-inputted rates of change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional power supplies adjust current to LED loads immediately to reduce temperature, then LED temperature reduction speed is improved, but lighting artifacts such as flickering occur
Solution Approach 1:
The power supply dynamically adjusts the current change rate based on operating conditions. The controller modifies the current waveform characteristics in real-time, transitioning from immediate step changes to gradual ramps, thereby adapting the system's response speed to balance temperature reduction with light emission stability.
Solution Approach 2:
The patent changes the temporal parameter of current delivery by introducing a rate-of-change limitation. Instead of delivering current changes instantaneously, the system controls the derivative of current with respect to time, transforming the parameter space from immediate response to controlled gradual adjustment.
2Loss of time
If conventional power supplies provide immediate current changes to LED loads, then response time is improved, but user experience deteriorates due to visible light emission changes
Solution Approach 1:
The system employs dynamic current adjustment where the rate of change is modulated based on the magnitude of temperature deviation and desired response. The controller continuously adapts the current waveform slope, creating a dynamic balance between quick response and smooth light output that maintains user comfort.
Solution Approach 2:
The power supply incorporates feedback mechanisms that monitor both temperature conditions and light output characteristics. This feedback loop enables the controller to adjust the current change rate in real-time, preventing excessive light emission variations while still responding adequately to temperature conditions.
3Reliability
If power supply reduces current quickly to prevent LED damage, then LED protection is improved, but lighting stability deteriorates
Solution Approach 1:
The patent introduces a controlled rate-of-change parameter that limits how quickly current can be reduced. This parameter transformation ensures that protective current reduction occurs at a pace that prevents both LED damage and noticeable light emission fluctuations, maintaining system reliability while preserving lighting stability.
Solution Approach 2:
The system implements a cushioning effect by pre-limiting the maximum rate of current change. This beforehand constraint acts as a buffer that prevents abrupt transitions, cushioning the system against both thermal damage and light output instability, ensuring smooth protective action.
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 solution effectively minimizes lighting artifacts and prevents LED damage by gradually adjusting the current, ensuring stable light emission and extending the lifespan of the LEDs.
Implementation Method 1
The power supply can be configured to detect LED over-temperature conditions and to adjust output current to the LED in response
Implementation Method 2
a power supply provides a stable current to the LED... An LED's temperature is generally proportional to the current flowing through the LED
Data Source
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AI summary
Embodiments disclosed herein describe the use of a power supply to provide power to an LED load. The power supply provides a present output current to the LED, and receives a temperature signal representing the operating temperature of the LED. A target output current is determined, for instance based on the temperature signal. An output current rate of change is determined, and the power supply adjusts the output current to the LED at the determined rate of change until the output current is substantially equal to the target current.