LED Dimming Module with Bleeding Circuit for Triac Compatibility
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Solution Overview
Problem
Existing dimming systems for LED lighting, particularly those using triac or thyristor devices, face compatibility issues with LED driver circuits and struggle to provide effective dimming signals, leading to inefficiencies and potential errors in power transmission.
Innovation Solution
A dimmable LED module with a bleeding circuit that selectively draws a bleeding current when the supply voltage amplitude is below a threshold, enabled/disabled with a frequency higher than twice the AC supply voltage, and a control circuit that processes bleeding activity signals to determine the phase cut and adjust power supplied to the LEDs, using PWM control or DC current modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a triac or thyristor dimmer is used to control LED lighting, then phase cut dimming functionality is achieved, but compatibility issues with LED driver circuits occur and voltage drift is caused
Solution Approach 1:
A bleeding circuit is introduced as an intermediary component between the triac dimmer and the LED driver circuit. This circuit includes a bleeding resistor connected in parallel with the LED driver, providing a continuous path for triac holding current during phase cut dimming operations. The bleeding circuit mediates the interaction between the dimmer and LED driver, preventing voltage drift and ensuring stable operation while maintaining compatibility with phase cut dimming control.
2Loss of energy
If phase cut dimming is implemented with LED drivers, then energy saving is achieved, but dimming signal detection accuracy deteriorates
Solution Approach 1:
The system implements feedback by monitoring the current through the bleeding resistor and using this information to accurately detect the phase cut dimming signal. The control circuit measures the voltage across the bleeding resistor, which provides feedback about the triac conduction state and phase angle. This feedback mechanism enables precise detection of dimming signals while maintaining energy savings, as the bleeding circuit operates continuously at low power to provide detection reference.
3Reliability
If a bleeding circuit is continuously active to support triac holding current, then voltage stability is improved, but energy consumption increases
Solution Approach 1:
The bleeding circuit operates periodically rather than continuously, being activated only during the critical periods when triac holding current is needed during phase cut dimming operations. The circuit is controlled by a detection mechanism that activates the bleeding resistor when phase cut dimming is detected and deactivates it when not needed. This periodic operation maintains voltage stability and supports triac functioning while minimizing unnecessary energy consumption during full power operation.
Data Source
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AI summary
The invention relates to a dimmable LED module, the module being designed for being dimmed using a dimmer controlling a phase cut of an AC supply voltage supplied to the LED module, the module comprising : a bleeding circuit for selectively acting to draw a bleeding current in periods when the supply voltage amplitude is below a threshold value, a control circuit being supplied with a signal indicating the activity of the bleeding circuit, the control circuit determining, based on the bleeding activity indication signal, a value representing the phase cut present in the AC supply voltage and issuing a control signal as a function of the phase cut value, and at least one driver circuit being supplied with said control signal and adjusting the power supplied associated LED lighting means.