LED Driving Circuit Control for Power Loss Reduction
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Solution Overview
Problem
Conventional LED control circuits face inefficiencies due to power losses and reduced power factor in LED drivers, particularly in multi-stage switching converters, which increase product costs and complicate current balance in LED branch circuits.
Innovation Solution
The proposed solution involves a control circuit for an LED driving circuit that regulates the driving voltage of a power transistor to vary with the rectifier output voltage, controlling the current flowing through the transistor to be consistent with or opposite to the rectifier output voltage, thereby reducing power losses and improving the power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-stage switching converters are used to adjust LED brightness, then brightness control capability is improved, but power losses increase and product costs increase
Solution Approach 1:
The patent extracts the brightness control function from a multi-stage switching converter architecture and implements it using a single-stage flyback converter with a divided secondary winding. By taking out the unnecessary second stage DC-DC converter and keeping only the essential brightness control functionality in the first stage, the design reduces power losses while maintaining brightness control capability.
Solution Approach 2:
The patent segments the secondary winding of the flyback converter into two separate groups (first and second groups), allowing independent connection to different LED branch circuits. This segmentation enables flexible brightness control of individual LED groups while using a single-stage converter, thereby reducing overall power losses compared to multi-stage architectures.
2Adaptability or versatility
If multi-stage switching converters are used to adjust LED brightness, then brightness control capability is improved, but product costs increase
Solution Approach 1:
The patent removes the second stage DC-DC converter from the multi-stage architecture, keeping only the essential first stage flyback converter. This extraction reduces component count and circuit complexity, leading to lower manufacturing costs while preserving the core brightness control functionality through the divided secondary winding.
3Manufacturing precision
If linear regulator is coupled with LED branch circuit to regulate current, then current balance is improved, but power losses increase
Solution Approach 1:
The patent uses the divided secondary winding groups as intermediaries to provide separate current paths for different LED branch circuits. By controlling the connection of these winding groups through switching elements, the system achieves current balance across LED branches without requiring additional linear regulators, thereby avoiding the power losses associated with LDO-based current regulation.
Data Source
AI summary
A control circuit for an LED driving circuit having a rectifier and a power transistor for driving an LED load, can include: a control signal regulation circuit configured to control a driving voltage of the power transistor to vary with a rectifier output voltage to control the variation of a current flowing through the power transistor to be consistent with that of the rectifier output voltage to decrease a power loss of the power transistor; and the control signal regulation circuit being configured to control the driving voltage of the power transistor to vary with the rectifier output voltage to control the variation of the current flowing through the power transistor to be opposite to that of the rectifier output voltage to improve a power factor of the LED driving circuit.