Dimming Controller for LED Current Control via Secondary Winding Feedback
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Solution Overview
Problem
Existing light-emitting diode (LED) driving circuits can only provide one or two dimming methods, such as phase truncation (TRIAC), pulse-width modulation (PWM), and analog level dimming, with insufficient control accuracy and inability to implement all three dimming manners simultaneously.
Innovation Solution
A dimming driving system with a transformer and a dimming controller integrated into a chip, featuring phase truncation, PWM, and analog level dimming capabilities, utilizing a processing circuit to prioritize dimming signals and generate current setting signals for precise control of current flowing through LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase truncation (TRIAC) dimming is used to control LED current, then the dimming function is provided, but the control accuracy is insufficient and other dimming functions cannot be provided
Solution Approach 1:
The dimming controller is designed to accept multiple types of dimming signals (phase truncation/TRIAC dimming, PWM dimming, and analog level dimming) through a unified interface. The processing circuit identifies the signal type and processes it accordingly, enabling the system to provide multiple dimming functions simultaneously while maintaining accurate control through secondary-side detection and feedback mechanisms.
2Device complexity
If control chip provides only one or two dimming manners, then the device complexity is reduced, but the adaptability and versatility are limited
Solution Approach 1:
The dimming controller integrates multiple dimming signal processing capabilities into a single chip. The processing circuit includes signal identification functionality that detects whether the input signal is phase truncation, PWM, or analog level type, and processes each type appropriately. This allows one chip to replace what would traditionally require multiple specialized controllers.
Solution Approach 2:
The patent introduces a secondary-side detection mechanism that detects the voltage drop across the secondary winding and provides feedback to the controller. This intermediary feedback path enables the controller to accurately regulate LED current regardless of the dimming signal type used, resolving the conflict between supporting multiple dimming methods and maintaining control accuracy.
3Ease of operation
If primary side control is used for phase truncation dimming, then the dimming function is achieved, but the current control accuracy through secondary side is not enough
Solution Approach 1:
The patent introduces a secondary-side detection mechanism that detects the voltage drop across the secondary winding and provides feedback to the controller. This intermediary feedback path enables the controller to accurately regulate LED current regardless of the dimming signal type used, resolving the conflict between supporting multiple dimming methods and maintaining control accuracy.
Solution Approach 2:
The controller implements a feedback mechanism by detecting the voltage drop on the secondary side and using this information to regulate the LED current. The feedback loop continuously monitors the actual current and adjusts the switching control to maintain the desired current level, significantly improving control accuracy compared to open-loop primary-side 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
Enables accurate implementation of phase truncation, PWM, and analog level dimming, providing higher control precision and flexibility in managing LED current, thereby enhancing the dimming functionality of LED driving circuits.
Implementation Method 1
The transformer has a primary winding and a secondary winding inductively coupled to each other
Data Source
AI summary
Disclosed are dimming driving system and a dimming controller. A disclosed dimming driving system has a transformer, a lighting device, and a dimming controller. The transformer has a primary winding and a secondary winding inductively-coupled to each other. The secondary winding is coupled to an output power line and secondary ground, both coupling to and powering the lighting device. The dimming controller is coupled to the secondary winding for controlling current flowing through the lighting device according to a voltage drop of the secondary winding.