LED Lighting Device Multi-Stage Current Control for Harmonic Reduction
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Solution Overview
Problem
Conventional LED lighting devices directly driven by rectified AC voltage face challenges in reducing current harmonic, which can stress low-voltage AC public mains networks and violate European Standard EN 61000-3-2 for maximum permissible harmonic current.
Innovation Solution
The LED lighting device employs multiple driving stages with a first luminescent device driven by rectified AC voltage, coupled with a current sensing element and a current regulator that provides a regulating current setting following the waveform of the rectified AC voltage, and a second luminescent device with a current controller to maintain a constant regulating current, improving current harmonic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LEDs are light up in stages to increase effective operational voltage range, then the operational voltage range is improved, but current harmonic increases
Solution Approach 1:
The LED lighting device is divided into multiple driving stages with separate current control circuits. Each stage has its own current sensing element and current regulator, allowing independent control of current in each voltage range. This segmentation enables the system to maintain adaptability across different voltage ranges while controlling harmonic current in each segment separately.
Solution Approach 2:
The patent implements dynamic current regulation where the first current regulator provides a regulating current setting that follows the waveform of the rectified AC voltage, while the second current controller maintains a constant regulating current setting. This dynamic adjustment of current control strategies across different operating conditions allows the system to adapt to varying voltage ranges while minimizing harmonic current injection.
2Adaptability or versatility
If multiple driving stages are used to expand operational voltage range, then adaptability is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into multiple independent current control circuits, each responsible for a specific voltage range. This modular segmentation allows the system to achieve wide adaptability while keeping each control module relatively simple and manageable.
Solution Approach 2:
Each current control circuit is designed to be multi-functional, handling both current regulation and harmonic control within its designated voltage range. The first current regulator and second current controller work together as a universal control system that adapts to different operating conditions without requiring completely separate control mechanisms.
Data Source
AI summary
An LED lighting device includes at least two luminescent devices, two current sensing elements, and two current regulators. The first and second luminescent device are driven by a rectified AC voltage for providing light according to first current and second current, respectively. The first current sensing element provides a first feedback voltage associated with the first current and the second current sensing element provides a second feedback voltage associated with the second current. The first current regulator provides a first regulating current setting according to the first feedback voltage and a line voltage detection voltage associated with the rectified AC voltage, wherein the waveform of the first regulating current setting follows the waveform of the rectified AC voltage. The second current controller is coupled in parallel to the second luminescent device and provides a constant second regulating current setting according to the second feedback voltage.