LED Driving Circuit Ripple Compensation via Dynamic Current Distribution
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Solution Overview
Problem
Current LED driving circuits face challenges in reducing light flicker caused by current ripple while maintaining cost-effectiveness and efficiency, especially in professional lighting applications where high light uniformity is required.
Innovation Solution
The proposed LED driving circuit dynamically adjusts the distribution of input current between LED segments based on the instantaneous value of the current ripple, providing all current to one segment during peak periods and splitting it between segments during valley periods to optimize light conversion efficiency and reduce flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single stage driver with PFC is used to reduce cost, then driver cost is reduced, but current ripple increases causing light flicker
Solution Approach 1:
The LED load is divided into multiple LED channels that can be independently controlled. The current distributing circuit selectively activates different LED channels based on the instantaneous current ripple conditions, thereby segmenting the impact of ripple on light output and reducing perceptible flicker.
Solution Approach 2:
The system dynamically adjusts which LED channels are active based on the instantaneous value of current ripple. During peak ripple portions, different LED channels are activated compared to valley portions, creating a dynamic response that compensates for ripple effects and reduces light flicker.
2Object-affected harmful factors
If current is split between multiple LED channels using PWM to reduce flicker, then light uniformity improves, but light conversion efficiency decreases
Solution Approach 1:
Instead of continuously splitting current across multiple LED channels, the system applies partial action by selectively activating specific LED channels only during peak ripple portions. This reduces the overall time that current is divided, thereby maintaining higher light conversion efficiency while still addressing flicker during critical periods.
Solution Approach 2:
The current distributing circuit implements periodic switching between different LED channels synchronized with the ripple cycle. By activating different channels during peak and valley portions periodically, the system maintains light uniformity while allowing each LED channel to operate at higher efficiency during its active periods.
3Adaptability or versatility
If linear control mode is used to tune currents between LED channels, then color temperature control is achieved, but light conversion efficiency is reduced
Solution Approach 1:
The system segments the LED channels into groups associated with different color temperatures. By selectively activating specific LED channel groups based on desired color temperature output, the system achieves color temperature control without requiring linear control mode, thereby avoiding the associated power losses.
Solution Approach 2:
The current distributing circuit dynamically selects which LED channels are active based on both the ripple conditions and the desired color temperature. This dynamic channel selection enables color temperature tuning while maintaining higher efficiency by avoiding continuous current splitting through linear control.
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
This approach effectively compensates for current ripple, achieving a more constant light output with reduced flicker and increased efficiency, while maintaining cost-effectiveness by using existing components and minimizing power loss.
Implementation Method 1
the light conversion efficiency of the single LED segment is lower than a light conversion efficiency of the at least two LED segments
Data Source
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AI summary
A LED driving circuit (20) is for driving at least two LED segments (22, 24) of different color or color temperature, using an input current which has a current ripple amplitude. The LED driving circuit (20) comprises an input to receive the input current; an output to connect to the at least two LED segments (22, 24); and a current distributing circuit which provides the input current to a single one of the two LED segments when the current is at a peak portion, wherein the current distributing circuit is adapted, when providing the input current to a single one of the two LED segments during the peak portion, to provide the input current to the single one of the two LED segments alternately, and splits the input current into two non-zero currents for different LED segments when the current is in a trough. When all current is provided to one LED segment, the light conversion efficiency is lower than when two segments are driven with lower current. This means the effect which the current ripple has on the light output is reduced. The driving circuit effectively compensates for the current ripple by adjusting the light conversion efficiency so that a flatter light output characteristic is obtained.