LED Driver Bleeder Circuit for SCR Dimmer Compatibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LED drivers with silicon-controlled dimmers face compatibility issues due to low input current causing the dimmer to turn off when the conduction angle is small, resulting in asymmetric voltage waveforms and flickering light sources.
Innovation Solution
Incorporating a bleeder circuit coupled with a controller that draws a bleeder current from the DC bus when the conduction angle of the silicon-controlled dimmer is less than a threshold, maintaining conduction and improving compatibility by ensuring the input current meets or exceeds the holding current of the dimmer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the conduction angle of the silicon-controlled dimmer is small, then the input current is low, but the dimmer turns off due to insufficient holding current
Solution Approach 1:
The patent introduces a capacitor as an intermediary energy storage element between the rectifier circuit and the silicon-controlled dimmer. This capacitor stores energy during periods of sufficient input current and releases it during periods of low current, acting as a buffer that maintains the holding current required by the dimmer throughout the entire conduction cycle, thereby preventing premature turn-off and ensuring stable operation.
2Use of energy by moving object
If the input current is low, then energy consumption is reduced, but the dimmer cannot maintain conduction state
Solution Approach 1:
The patent changes the electrical parameters at the dimmer input by introducing a capacitor that modifies the current waveform. The capacitor charges and discharges to maintain a minimum holding current level, effectively transforming the input current profile from a low-current pulse to a sustained current that meets the dimmer's holding current requirement, thereby improving compatibility without increasing overall energy consumption.
3Productivity
If the conduction angle is small, then the LED driver operates efficiently, but asymmetric voltage waveforms cause flickering
Solution Approach 1:
The patent applies preliminary action by charging the capacitor during the early phase of the AC cycle when input current is sufficient. This stored energy is then released during the latter phase when current would otherwise be insufficient, proactively preventing the asymmetric waveform and flickering before they occur, thereby maintaining voltage waveform symmetry without compromising operational efficiency.
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 extends the conduction time of the silicon-controlled dimmer, preventing flickering and ensuring compatibility by maintaining a consistent DC bus voltage, thereby enhancing the reliability and efficiency of the LED lighting system.
Implementation Method 1
an apparatus for an LED driver with a silicon-controlled dimmer
Implementation Method 2
a bleeder circuit coupled to a DC bus of the LED driver... draw a bleeder current from the DC bus
Data Source
AI summary
An apparatus for an LED driver with a silicon-controlled dimmer, can include: a bleeder circuit coupled to a DC bus of the LED driver; and a controller configured to control the bleeder circuit to draw a bleeder current from the DC bus when a conduction angle of the silicon-controlled dimmer is less than an angle threshold, in order to maintain a conduction state of the silicon-controlled dimmer.