LED Dimmer Circuit Eliminates Bleeder Current for TRIAC Stability
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Solution Overview
Problem
Existing dimmable LED lighting systems using phase-cut dimmers often experience premature TRIAC reset due to insufficient holding current, leading to flicker or failure, and require bleeder currents that consume extra power and reduce efficiency, necessitating separate dimmable and non-dimmable lamp types.
Innovation Solution
A dimmer circuit that adjusts the brightness of LED lamps by controlling the phase-cut period of AC voltage without requiring a bleeder current, using a power supply circuit with a bridge rectifier, zero-cross detection, timing, and gate driver to independently manage the dimming operation, compatible with both dimmable and non-dimmable lamps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder circuit is used to provide holding current for the TRIAC, then the TRIAC can maintain conducting state without premature reset, but the LED lamp consumes extra power continuously and system efficiency decreases
Solution Approach 1:
The patent extracts the bleeder circuit function from the LED lamp circuit by introducing a separate parallel circuit with a bleeder resistor that provides the holding current independently. This allows the TRIAC to maintain conducting state without requiring the LED lamp to continuously conduct current, thereby resolving the contradiction between reliability and energy consumption.
2Reliability
If a bleeder circuit is used to maintain TRIAC conduction, then the dimmer can operate without premature turn-off, but flicker occurs especially at low dimming levels due to interference between dimmer switch and LED lamp operation
Solution Approach 1:
The patent separates the bleeder current path from the LED lamp circuit by introducing a parallel circuit with a bleeder resistor. This extraction eliminates the interference between the dimmer switch operation and LED lamp operation that causes flicker, while still maintaining TRIAC conduction stability. The dimmer can now operate independently without causing the LED lamp to flicker at low dimming levels.
3Ease of operation
If phase-cut dimmer is used to regulate power to LED lamp, then brightness can be adjusted, but insufficient holding current causes TRIAC to reset prematurely leading to light flicker or complete failure
Solution Approach 1:
The patent introduces a bleeder resistor as an intermediary element that provides the necessary holding current to the TRIAC independently of the LED lamp circuit. This intermediary component acts as a mediator between the phase-cut dimmer control signal and the TRIAC switching operation, ensuring the TRIAC maintains conducting state throughout the AC cycle and prevents premature reset, thereby resolving the contradiction between ease of operation and reliability.
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 eliminates the need for bleeder currents, reducing power consumption and improving system efficiency while allowing seamless integration of all lamp types without compatibility issues, minimizing flicker and ensuring stable dimming performance.
Implementation Method 1
a bridge rectifier, zero-cross detection, timing, and gate driver
Implementation Method 2
zero-cross detection
Data Source
AI summary
A dimmer circuit is used in an LED lighting system which includes a power supply circuit and a lamp. The power supply circuit is configured to provide an AC voltage. The lamp is coupled to the power supply. The dimmer circuit is configured to adjust the brightness of the lamp according to a dimming signal without the lamp conducting a bleeder current during each cycle of the AC voltage.