LED Driver Buffer Circuit for Fast Modulation and Energy Recovery
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Solution Overview
Problem
Constant current LED drivers face challenges in fast and lossless output current modulation due to slow PI control loops, resulting in significant turn-off and turn-on delay times and current overshoot, which negatively impact communication reliability.
Innovation Solution
The implementation of an energy recovery stage with a buffer circuit and controller that temporarily stores energy during modulation-off stages, enabling quick startup and minimizing power loss by selectively applying power from a buffer capacitor or a second voltage source, and converting error voltage signals into frequency or duty-ratio control inputs to manage the power converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a PI control loop is used to maintain constant current output, then current stability is improved, but modulation speed deteriorates due to slow response
Solution Approach 1:
The patent stores the error voltage signal before modulation in a buffer circuit, preparing the control signal in advance. This preliminary action allows the system to quickly restore current after modulation without waiting for the PI loop to recalculate, thereby improving modulation speed while maintaining current stability through the pre-prepared error signal.
2Speed
If output current is rapidly modulated for communication, then communication speed is improved, but current overshoot increases causing reliability issues
Solution Approach 1:
The buffer circuit stores the error voltage signal before modulation occurs, preparing the corrective control signal in advance. This preliminary preparation ensures that when rapid current modulation is needed for communication, the system can immediately apply the pre-calculated error signal to prevent overshoot, thereby maintaining both high communication speed and current control reliability.
3Loss of time
If turn-off delay time is reduced for faster modulation, then response time is improved, but energy loss increases
Solution Approach 1:
The patent recovers energy stored in the output capacitor during turn-off by redirecting it to charge the buffer capacitor. This energy recovery mechanism allows the system to achieve fast turn-off response without significant energy loss, as the stored energy is reused rather than dissipated. The recovered energy charges the buffer capacitor, which then provides the error signal for the next modulation cycle.
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 solution reduces turn-on and turn-off delay times, current overshoot, and power loss during LED output current modulation, ensuring reliable communication and efficient energy recycling.
Implementation Method 1
A buffer circuit is coupled across the first and second ends of the load and configured to temporarily store energy for reuse when enabled
Implementation Method 2
An energy recovery circuit is coupled to both the feedback circuit and the controller. The energy recovery circuit has a second voltage source and is configured to selectively apply power to the feedback circuit and the controller from either the buffer circuit or the second voltage source
Data Source
AI summary
An LED driver for light modulation control includes a power converter circuit, a feedback circuit, a buffer circuit, an energy recovery circuit, and a controller. The power converter circuit is configured to provide an output current to an LED load coupled thereto. The feedback circuit is configured to generate an error signal which is fed back to the power converter circuit for maintaining the power converter circuit in a constant current output state. The buffer circuit is coupled to the LED load and configured for quick turn off of the LED load and for temporary storage of power. The energy recovery circuit is configured to reuse the power stored in the buffer circuit before relying on an external power source to power the controller and the feedback circuit. The controller is configured to control at least one aspect of each of the circuits of the LED driver.