LED Drive Circuit Resonance Management
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Solution Overview
Problem
Conventional LED illumination systems using phase control dimmers experience flickering due to resonance phenomena when driving LED loads, as the triac in the dimmer turns off at a holding current, leading to unstable energy supply and light control issues.
Innovation Solution
An LED drive circuit with a switch element connected in series to a capacitance and resistance component, which is turned off for a specific period after the dimmer is turned on, consuming resonance energy and preventing triac malfunction, and then turned on to stabilize the LED current control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a phase control dimmer is used to control LED illumination, then light control functionality is achieved, but resonance phenomenon causes the triac to turn off at holding current, leading to flickering
Solution Approach 1:
The patent applies preliminary action by detecting the turning-on state of the phase control dimmer in advance and proactively turning off the switch element before the resonance phenomenon can cause the triac to turn off. This preventive measure eliminates the flickering issue by ensuring the switch element is already off when the resonance occurs, thus maintaining stable energy supply throughout the LED drive circuit.
2Reliability
If the switch element is kept on continuously, then the LED current control circuit functions properly, but resonance energy causes triac malfunction and flickering
Solution Approach 1:
The patent applies preliminary anti-action by detecting the phase control dimmer's turning-on state and immediately turning off the switch element to counteract the harmful resonance phenomenon before it can cause triac malfunction. This approach directly neutralizes the resonance energy's harmful effects, preventing flickering while maintaining the LED current control circuit's proper functionality through the capacitor component.
3Loss of energy
If the triac turns off at holding current during resonance, then resonance energy is released, but energy supply to LED becomes unstable causing flickering
Solution Approach 1:
The patent converts the harmful resonance energy into a beneficial effect by using the detected phase control dimmer turning-on state as a trigger to turn off the switch element. This action channels the resonance energy through the capacitor component in a controlled manner, dissipating it safely while simultaneously preventing triac malfunction and maintaining stable illumination, thus transforming the harmful resonance into a manageable energy pathway.
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 configuration reduces flickering in LED illumination systems by managing resonance and ensuring stable energy supply, preventing triac turning off and enhancing the functionality of the LED current control circuit.
Implementation Method 1
resonance phenomenon occurs. In a load, such as the LED load 400 (FIG. 7), whose load is low, the absolute value of a current flowing thorough the triac Tri reaches a holding current (for example, about 10 mA) or less
Implementation Method 2
a capacitance component CA and a resistance component RA that are connected in series between an input of the LED current control circuit 2 and a reference potential
Data Source
AI summary
There is provided an LED drive circuit that can be connected to an alternating-current power supply through a phase control dimmer and that drives an LED load, the LED drive circuit including: an LED current control circuit; a capacitance component and a resistance component that are connected in series between an input of the LED current control circuit and a reference potential; a switch element that is connected to both ends of the resistance component; and a switch control portion that turns off the switch element for a given period of time after a timing when the phase control dimmer is turned on and that turns on the switch element after the given period of time elapses.