LED Control Circuit for Phase-Cut Dimmer Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED lighting systems experience visible flicker and ripple due to link voltage-induced issues when using phase-cut dimmers, which are not efficiently addressed by current technologies.
Innovation Solution
A switching power converter with a current source and a control node, coupled with a sense node, is used to regulate the LED lighting system, allowing the lighting system controller to adjust the control current based on sensed parameters to minimize ripple and maintain a constant voltage, thereby reducing flicker and ripple in the LED lighting system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phase-cut dimmers are used to control LED lighting systems, then dimming capability is improved, but visible flicker and ripple increase
Solution Approach 1:
The patent introduces an intermediary circuit between the phase-cut dimmer and the LED driver that acts as a buffer. This intermediary circuit captures and stores the chopped AC waveform energy, then releases it smoothly to the LED driver, preventing the direct transmission of dimming-induced ripple and flicker to the LED lighting system.
Solution Approach 2:
The patent changes the electrical parameters of the system by introducing a capacitive element that alters the waveform characteristics. The capacitor converts the chopped AC waveform into a smoother voltage profile, changing the frequency and amplitude parameters to eliminate visible flicker while maintaining dimming functionality.
2Power
If link voltage is increased to improve power delivery, then energy transfer is improved, but ripple and disturbances increase
Solution Approach 1:
The patent converts the harmful ripple and disturbances in the link voltage into beneficial effects by using them to charge a capacitor. The capacitor then releases this energy in a controlled manner, transforming the harmful high-ripple voltage into a useful, smooth power source that improves overall system efficiency while eliminating the harmful effects.
3Device complexity
If conventional LED control circuits are used, then simplicity is maintained, but efficiency and stability deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the circuit monitors its own performance and adjusts operation accordingly. The feedback loop detects inefficiencies and stability issues, then modifies the control parameters to optimize energy transfer and reduce losses, maintaining simplicity while improving efficiency through intelligent control.
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 solution effectively reduces ripple and flicker in LED lighting systems, ensuring stable and efficient operation with reduced link voltage-induced disturbances, maintaining a power factor close to one and minimizing energy wastage.
Implementation Method 1
Switching power converter 102 includes a switch 108 that operates in response to a control signal CS to regulate the transfer of energy from the rectified, time-varying input voltage Vx(t), through inductor 110 to capacitor 106
Implementation Method 2
Capacitor 106 has sufficient capacitance to maintain an approximately constant voltage VC while providing current to a load, such as LED lighting subsystem 112
Implementation Method 3
The brightness of an LED varies in direct proportion to the current flowing through the LED
Data Source
AI summary
A light emitting diode (LED) lighting system includes a switching power converter having an input for coupling to an alternating current (AC) power source, an output, and a switch. The LED lighting system also includes an LED lighting subsystem coupled to receive power from the output of the switching power converter. The LED lighting subsystem includes a current source for one or more LEDs, and the current source has a control node and a sense node. The LED lighting system additionally includes a switch state controller coupled to the switching power converter and coupled to the LED lighting subsystem. The switch state controller controls switching of the switch and varies a control current provided to the control node of the current source based on at least a parameter sensed from the sense node.