Adjustable Impedance Tube Reduces LED Driver Current Ripple
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Solution Overview
Problem
Current sources, particularly LED drivers, experience current ripple due to internal circuitry, leading to stroboscopic phenomena and reduced LED light service life, necessitating a method to reduce output current ripple across different amplitude values and adjustable current sources.
Innovation Solution
A circuit comprising an adjustable impedance tube and control circuit that compares instantaneous current values with set signals based on average current values, adjusting impedance to ensure the current does not exceed set amplitudes, thereby reducing ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the speed of current controlling loop is low or filter capacity is small, then device complexity is reduced, but current ripple increases causing stroboscopic phenomenon
Solution Approach 1:
The patent introduces an adjustable impedance tube as an intermediary element between the current source and LED load. This impedance tube acts as a mediator that smooths current ripple without requiring complex filtering circuits or high-speed control loops, thus reducing device complexity while eliminating the harmful stroboscopic effect
Solution Approach 2:
The patent dynamically adjusts the impedance parameter of the impedance tube based on real-time current detection. By changing the impedance parameter adaptively, the system能够有效 suppress current ripple across different operating conditions without requiring complex fixed-parameter circuits
2Adaptability or versatility
If current amplitude is adjusted for dimming function, then adaptability is improved, but current ripple varies with different amplitudes making control more difficult
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously detects the output current and adjusts the impedance tube's impedance accordingly. This closed-loop feedback ensures that current ripple is suppressed across all current amplitudes, maintaining stable LED brightness without stroboscopic effects during dimming operations
Solution Approach 2:
The patent employs dynamic impedance adjustment rather than fixed impedance. The impedance tube's impedance changes dynamically based on the operating conditions and detected current ripple, enabling effective ripple suppression across the full range of current amplitudes for dimming functions
Data Source
AI summary
Disclosed are a method and circuit for reducing a ripple of a current output by a current source. The circuit for reducing a ripple of a current output by a current source comprises a tube with adjustable impedance and a control circuit. The control circuit detects a direct current output by the current source to obtain a first signal which is in proportion to the direct current, and by comparing an instantaneous value of the first signal with an amplitude value of a set signal, controlling the increase of the impedance of the tube with adjustable impedance when the instantaneous value of the first signal is greater than the amplitude value of the set signal, so as to enable the amplitude value of the first signal to not exceed the amplitude value of the set signal and then enable the amplitude value of the current output by the current source to not exceed the amplitude value of the set current of the set signal, so that the purpose of reducing the ripple of the direct current output by the current source is finally achieved.