Multi-Stage LED Driver with Unified Current Regulation
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Solution Overview
Problem
Conventional LED lighting devices driven by rectified AC voltage struggle with effective operational voltage range and line/load regulation, as current regulation in each stage is independent, leading to inconsistent brightness and power delivery.
Innovation Solution
The LED lighting device incorporates multiple driving stages with voltage and current controllers that monitor rectified AC voltage variations, adjusting current settings to maintain consistent brightness across stages, using a voltage detector to generate compensation voltages and adjust current controllers to regulate currents within set limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple driving stages are used to increase effective operational voltage range, then the operational voltage range is improved, but line/load regulation deteriorates due to independent current regulation in each stage
Solution Approach 1:
The patent merges the current regulation functions of multiple driving stages into a single unified current controller that regulates current across all stages simultaneously. This is achieved by connecting the cathode of each LED string to the anode of the next stage and using one current controller to regulate the entire series-parallel configuration, ensuring consistent current flow and improving line/load regulation while maintaining the extended operational voltage range provided by multiple stages.
2Device complexity
If independent current regulation is used in each stage, then device complexity is reduced, but brightness consistency deteriorates
Solution Approach 1:
The patent combines multiple LED strings from different stages into a single current regulation system. By connecting LED strings in series-parallel configuration and using one current controller to regulate the total current, the system achieves uniform brightness across all stages while maintaining relatively simple device structure. The unified current regulation ensures that all LED strings receive the same current, eliminating brightness inconsistency without requiring complex independent control circuits for each stage.
Data Source
AI summary
An LED lighting device includes multiple luminescent devices driven by a rectified AC voltage. The multiple luminescent devices are turned on flexibly in a multi-stage driving scheme using multiple current controllers. The current settings of the two driving stages with the highest current level and the second highest current level are adjusted according to the variation in the rectified AC voltage VAC or according to the variation in the duty cycle of the luminance device due to the variation in the rectified AC voltage. The present invention can improve the line/load regulation of the LED lighting device when the rectified AC voltage somehow fluctuates between its upper bound and lower bound.