Two-Stage Light Driver DC-Level Control for Low-Dimming Flicker
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Solution Overview
Problem
LED lighting systems experience flicker and shimmer due to inherent ripple in the drive signal, particularly at low dimming levels, which existing technologies fail to adequately address.
Innovation Solution
A two-stage light driver system with a regulator and secondary controller that employs independent feedback loops to reduce ripple and eliminate flicker by dynamically controlling the DC-level of the drive signal, using a secondary controller to monitor and adjust the regulator and converter based on voltage and current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage converter is used to drive LEDs, then the device complexity is low, but output ripple and flicker increase
Solution Approach 1:
The patent divides the single-stage converter into two independent stages: a first converter generating a drive signal and a second converter generating a regulated signal. Each stage has its own feedback control loop, separating the functions of voltage conversion and current regulation to reduce output ripple and flicker while maintaining manageable complexity in each individual stage.
2Stability of the object's composition
If feedback control is implemented to reduce ripple, then output stability improves, but device complexity increases
Solution Approach 1:
The patent implements feedback control in both converter stages: a first feedback loop monitors the drive signal and adjusts the first converter, while a second feedback loop monitors the regulated signal and adjusts the second converter. This dual feedback mechanism stabilizes the LED output by continuously correcting ripple and fluctuations without requiring overly complex control circuitry, as each feedback loop operates independently on its respective stage.
Data Source
AI summary
A light driver includes a converter configured to generate a drive signal for driving an output load based on a rectified input signal; a regulator coupled between the converter and the output load, and configured to generate a regulated signal based on the drive signal; a secondary controller configured to detect a voltage of the regulator, to generate a first feedback signal to dynamically control a DC-level of the drive signal based on the voltage of the regulator, and to generate a second feedback signal for controlling a DC-level of the regulated signal.