Flicker Suppression Circuit for Dimmable LED Bulbs
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Solution Overview
Problem
Conventional TRIAC-based dimmers for LED light bulbs experience flickering due to insufficient current flow below the TRIAC's holding current, leading to instability and rapid turn-on and turn-off of LEDs, as they rely on phase angle control and DC converters that fail to maintain power delivery effectively.
Innovation Solution
A flicker suppression system that includes a rectifier circuit, a resistor, and a switch control circuit, which selectively couples a bleeder resistor in parallel with the LED light bulb to maintain a minimum current flow during TRIAC activation, ensuring the TRIAC remains latched and power is consistently delivered, thereby reducing or eliminating flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phase angle control is used to dim LED light bulbs, then power delivery can be adjusted, but flickering occurs due to insufficient current flow below TRIAC holding current
Solution Approach 1:
The circuit performs preliminary action by detecting the TRIAC current status in advance and proactively connecting the bleeder resistor when current falls below holding current, preventing flickering before it occurs. The switch control circuit monitors current flow and activates the bleeder resistor preemptively during dimming operations.
Solution Approach 2:
The bleeder resistor acts as an intermediary element that provides a alternative current path when the main load current is insufficient. It mediates between the TRIAC and the LED driver, ensuring minimum holding current is maintained even when dimming reduces the primary load current below the TRIAC's holding threshold.
2Reliability
If a bleeder resistor is connected in parallel with LED light bulb, then current flow is maintained above TRIAC holding current, but power losses increase
Solution Approach 1:
The circuit dynamically adjusts the bleeder resistor connection based on real-time current conditions. The switch control circuit continuously monitors TRIAC current and only connects the bleeder resistor when current falls below holding current threshold, making the system adaptive rather than static. This dynamic approach minimizes energy loss by activating the bleeder resistor only when necessary.
Solution Approach 2:
The circuit changes the operational parameters by modifying the effective load impedance through switchable parallel resistance. When dimming operations cause current to drop below holding current, the bleeder resistor is introduced to change the total load parameters, ensuring TRIAC remains latched. This parameter change is temporary and condition-based, optimizing energy efficiency.
3Reliability
If switch control circuit is directly coupled between output terminals, then flickering is suppressed by maintaining minimum current, but device complexity increases
Solution Approach 1:
The switch control circuit implements self-service by autonomously monitoring TRIAC current and automatically controlling the bleeder resistor connection without external intervention. The circuit detects current conditions and activates the bleeder resistor independently, eliminating the need for complex external control systems or additional sensing components.
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 flicker suppression system effectively maintains current above the TRIAC's holding current, preventing flickering and ensuring stable power delivery to LED light bulbs, even at low power levels, while minimizing power losses and maintaining efficiency.
Implementation Method 1
A rectifier circuit 300 is provided and includes a bridge rectifier 310. The bridge rectifier 310 receives the line voltage and generates a rectified voltage.
Data Source
AI summary
A flicker suppression system for a dimmable LED bulb. In one embodiment, the system includes a rectifier circuit having input terminals and output terminals. The rectifier circuit is configured to rectify a line voltage to generate a rectified voltage at its output terminals. A resistor and switch are also included and coupled in series. A switch control circuit is directly coupled between the output terminals and configured to control the switch only as a function of the rectified voltage.