Lighting Converter THD Reduction via Dimming-Dependent Capacitance
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Solution Overview
Problem
Conventional converters for lighting control devices face challenges in managing total harmonic distortion (THD) and electromagnetic interference (EMI), particularly when brightness control (dimming) is involved, as existing standards only account for rated power and not for varying dimming levels.
Innovation Solution
A converter system that includes a filter circuit, full-wave rectifier circuit, power conversion circuit, and dimming control circuit, which adjusts the combined capacitance based on dimming levels to improve THD and EMI performance, meeting standards for each dimming level by outputting control signals to adjust capacitance accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the converter operates at low dimming levels, then the brightness control function is achieved, but the total harmonic distortion (THD) increases and may exceed regulatory standards
Solution Approach 1:
The patent applies dynamics by making the capacitance value adjustable based on operating conditions. The converter dynamically switches between different capacitance values (first capacitance for low dimming levels, second capacitance for high dimming levels) to optimize both THD performance and brightness control across different operating ranges.
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the converter based on the dimming level. By switching between different capacitance values, the converter adapts its electrical characteristics to maintain THD within standards while providing effective brightness control at various dimming levels.
2Illumination intensity
If the converter operates at low dimming levels, then the brightness control function is achieved, but the electromagnetic interference (EMI) increases and may exceed regulatory standards
Solution Approach 1:
The patent applies dynamics by making the capacitance value adjustable based on operating conditions. The converter dynamically switches between different capacitance values (first capacitance for low dimming levels, second capacitance for high dimming levels) to optimize both THD performance and brightness control across different operating ranges.
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the converter based on the dimming level. By switching between different capacitance values, the converter adapts its electrical characteristics to maintain EMI within standards while providing effective brightness control at various dimming levels.
3Device complexity
If a fixed capacitance is used in the converter, then the circuit design is simple, but the converter cannot meet THD and EMI standards across all dimming levels
Solution Approach 1:
The patent applies segmentation by dividing the capacitance into multiple discrete values (first capacitance and second capacitance) that can be selectively switched. This segmentation allows the converter to meet THD and EMI standards across different dimming levels while keeping the overall circuit design relatively simple through the use of switchable capacitor banks.
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 effectively reduces THD and EMI across different dimming levels, ensuring compliance with standards and maintaining optimal performance by dynamically adjusting capacitance in response to dimming level signals.
Implementation Method 1
a full-wave rectifier circuit configured to generate a full-wave rectified power from the input power with the noise component removed
Implementation Method 2
a filter circuit configured to remove a noise component included in input power
Implementation Method 3
a power conversion circuit configured to generate driving power of the lighting using the rectified power
Data Source
AI summary
A converter for a lighting control device for controlling lighting comprises: a filter circuit configured to remove a noise component included in an input power; a full-wave rectifier circuit configured to generate a full-wave rectified power from an input power from which a noise component has been removed; a power conversion circuit configured to generate a driving power of lighting by using a full-wave rectified power; and a dimming control circuit configured to output a dimming control signal for adjusting a driving power to the power conversion circuit, according to a dimming level indicating brightness of lighting, wherein the dimming control circuit outputs a first control signal to the full-wave rectifier circuit when the dimming level is less than a first reference value, and in response to the first control signal, the combined capacitance of the full-wave rectifier circuit is reduced, so that total harmonic distortion (THD) is reduced.