LED Driver Bleeding Current Adaptation for Dimmer Compatibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED driving apparatuses face efficiency limitations when compatible with dimmers, particularly due to the need for a single bleeding resistor to accommodate both leading edge and trailing edge dimming conditions, which results in suboptimal performance in both modes and further degradation in no dimming situations.
Innovation Solution
A controller is introduced in the LED driving apparatus that includes a dimming mode detector and a bleeding control circuit to differentiate between leading edge and trailing edge dimming conditions, adjusting the bleeding current accordingly based on sensed voltage thresholds, thereby optimizing efficiency by providing distinct bleeding currents for each mode and eliminating current when no dimmer is present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single bleeding resistor is designed to accommodate both leading edge dimming and trailing edge dimming, then compatibility with both dimming modes is achieved, but the efficiency of the LED driving apparatus deteriorates in both modes
Solution Approach 1:
The patent applies dynamics by making the bleeding current adjustable rather than fixed. The bleeding control circuit dynamically changes the bleeding current magnitude based on the detected dimming mode (leading edge or trailing edge), allowing the system to adapt its characteristics to match different operating conditions and eliminate the need for a compromise fixed resistor value
Solution Approach 2:
The patent changes the parameter of bleeding current from a fixed value to a variable value that can be adjusted based on the dimming mode. By detecting whether leading edge or trailing edge dimming is applied and相应地 adjusting the bleeding current magnitude, the system optimizes efficiency for each specific mode while maintaining compatibility with both
2Reliability
If a relatively small bleeding resistor is used to fit trailing edge dimming, then trailing edge dimming performance is improved, but efficiency in leading edge dimming and no dimming situations deteriorates
Solution Approach 1:
The system dynamically adjusts the bleeding current based on the detected dimming mode. When trailing edge dimming is detected, the bleeding control circuit sets the bleeding current to a larger value appropriate for that mode. When leading edge dimming is detected, it reduces the bleeding current to a smaller value, thereby optimizing efficiency for each specific mode rather than using a fixed compromise value
3Reliability
If a bleeding circuit is always active to improve dimming performance, then dimming performance is enhanced, but power loss increases in no dimming situations
Solution Approach 1:
The patent implements periodic action by making the bleeding circuit operate intermittently rather than continuously. The bleeding control circuit periodically evaluates the operating conditions and activates the bleeding circuit only when dimming modes are detected. In no-dimming situations, the bleeding circuit remains inactive, eliminating unnecessary power consumption while maintaining dimming performance when needed
Data Source
AI summary
An LED driving apparatus includes a rectifier bridge generating a DC bus voltage, a bus capacitor coupled between the output terminal of the rectifier bridge and a reference ground, a voltage sensing circuit generating a voltage sensing signal indicative of the DC bus voltage, a bleeding circuit providing a bleeding current for the bus capacitor, a switching converter configured to convert the DC bus voltage into a driving signal to drive an LED, a dimming mode detector detecting whether the LED driving apparatus is coupled to a leading edge dimmer or a trailing edge dimmer based on the voltage sensing signal, and a bleeding control circuit generating a control signal to control the bleeding circuit based on the voltage sensing signal, the leading edge dimming mode signal and the trailing edge dimming mode signal.