LED Driver TRIAC Dimmer Flicker Control
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Solution Overview
Problem
Conventional LED drivers are not dimmable when powered by a varying supply voltage from a TRIAC dimmer, leading to light flicker, inefficiency, and increased power dissipation, and they require large input filter capacitance which is costly and reduces Power Factor Correction (PFC) efficiency.
Innovation Solution
A lighting system with multiple LED units connected in series or parallel, a switch assembly for modifying the topology, and a control unit that adjusts the interconnection based on the supply voltage to maintain optimal load voltage, using a Buck or Boost converter to convert the input power source, and a waveform analyzer to synchronize with the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional LED drivers are powered by a varying supply voltage from a TRIAC dimmer, then the LED driver can be dimmed, but light flicker occurs and the driver becomes inefficient
Solution Approach 1:
The LED driver dynamically adjusts its operating parameters in response to the varying supply voltage from the TRIAC dimmer. The control circuit monitors the instantaneous voltage and modulates the LED current accordingly, transforming the static LED driver into a dynamic system that adapts to voltage variations, thereby eliminating flicker while maintaining dimming capability
Solution Approach 2:
The invention changes the electrical parameters (current, voltage, timing) of the LED driver based on the input voltage conditions. By adjusting the drive current waveform and timing parameters in response to the TRIAC dimmer's varying voltage, the system maintains stable LED operation across different dimming levels without flicker
2Stability of the object's composition
If a large input filter capacitance is used in the LED driver, then the power supply filtering is improved, but the size, weight, cost increase and Power Factor Correction efficiency decreases
Solution Approach 1:
The invention extracts the filtering function from the traditional large input capacitor and relocates it to the output side of the power converter. By placing the filter capacitor after the switching regulator, the system achieves effective power supply filtering with a much smaller capacitor, eliminating the need for large, heavy, and expensive input capacitors while improving PFC efficiency
Solution Approach 2:
The switching regulator acts as an intermediary between the varying supply voltage and the LED load. It converts the unstable input voltage into a stable output voltage, allowing the use of smaller filter capacitors. The regulator mediates the voltage variations, enabling effective filtering with reduced capacitance values
3Reliability
If a load is provided in parallel to the LED driver to ensure minimum holding current for the TRIAC, then the TRIAC conducting state is maintained, but power dissipation increases and efficiency decreases
Solution Approach 1:
The LED driver itself provides the holding current for the TRIAC through its normal operating current. By designing the driver to maintain sufficient current through the TRIAC during its conducting period, the system eliminates the need for separate parallel loading circuits. The driver serves its primary function while simultaneously maintaining TRIAC conduction, achieving self-service and improving efficiency
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 system allows for efficient dimming and retrofitting with reduced flicker, lower capacitance needs, and improved PFC, maintaining light intensity and color consistency while minimizing power loss and flicker effects.
Implementation Method 1
a power converter, such as a switching regulator or a linear regulator for powering an LED or assembly of LEDs
Data Source
Figure 1a
Figure 1b~2a
Figure 2b~3a
AI summary
The present invention relates to a lighting application, the lighting application can e.g. comprise an LED assembly comprising a serial connection of two or more LED units, each LED unit comprising one or more LEDs, each LED unit being provided with a controllable switch for substantially short-circuiting the LED unit. The lighting application further comprises a control unit for controlling a drive unit and arranged to receive a signal representing a voltage level of the supply voltage, and control the switches in accordance with the signal. The invention further provides for an LED driver that enables to operate a TRIAC based dimmer at an optimal holding current and an LED driver comprising a switchable buffer, e.g. a capacitor.