LED Lighting Control Circuit Dynamic Voltage Adjustment
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Solution Overview
Problem
Current multi-channel LED lighting systems face inefficiency due to a fixed bus voltage that increases losses as LEDs warm up, as the forward voltage decreases with temperature, leading to increased voltage headroom and reduced efficiency.
Innovation Solution
A lighting control circuit with a power converter and temperature sensing element that dynamically adjusts the DC voltage inversely with temperature, using a feedback circuit to maintain optimal voltage headroom, thereby improving efficiency by reducing voltage drop across current sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed bus voltage is used to drive LED channels, then the system is simple to operate, but efficiency deteriorates as LEDs warm up and forward voltage decreases
Solution Approach 1:
The patent implements dynamic voltage adjustment by introducing a temperature sensing element that monitors LED temperature and a feedback circuit that modifies the bus voltage accordingly. As temperature increases and forward voltage decreases, the system automatically reduces the bus voltage to maintain optimal voltage headroom, thereby minimizing power losses while maintaining stable LED operation.
Solution Approach 2:
The patent employs a feedback mechanism where the temperature sensing element continuously monitors LED temperature and feeds this information back to the power converter control circuit. This feedback loop enables real-time adjustment of the bus voltage based on actual LED operating conditions, optimizing efficiency dynamically rather than relying on fixed voltage settings.
2Reliability
If bus voltage is maintained high to accommodate cold LED startup, then reliable startup is achieved, but efficiency worsens when LEDs are warm due to increased voltage headroom
Solution Approach 1:
The system dynamically adjusts bus voltage based on real-time temperature conditions. During cold startup, the voltage sensing element detects low temperature and maintains higher bus voltage to ensure reliable LED ignition. Once LEDs are warm and forward voltage decreases, the system automatically reduces bus voltage to minimize voltage headroom and associated power losses, thus resolving the contradiction between startup reliability and operating efficiency.
Solution Approach 2:
The patent changes the operating parameter (bus voltage) dynamically based on temperature conditions. The feedback circuit modifies the voltage level according to LED temperature, transitioning from high voltage during cold startup to lower voltage during warm operation, thereby optimizing both reliability and efficiency across different operating states.
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
This solution enhances efficiency by adjusting the DC voltage based on temperature, reducing losses and maintaining optimal operation across varying temperatures, resulting in improved power management and reduced energy wastage.
Implementation Method 1
a temperature sensing element for sensing a temperature at or near the lighting arrangement
Implementation Method 2
a feedback circuit arranged to receive a measured voltage indicative of the DC voltage and arranged to provide a temperature-dependent control input to the control loop of the power converter
Data Source
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AI summary
A lighting arrangement such as a LED lamp comprises a light source and associated current driver, or a set of at least two parallel light sources and associated current drivers, supplied by a DC voltage from a voltage-regulated power converter. A feedback circuit provides a temperature-dependent control input to a control loop of the power converter, such that the DC voltage is adjusted in dependence on a sensed temperature. In this way, the voltage headroom required can be reduced, and efficiency gains are made.