Active Link Path Power Dissipation for Dimmer Hold Current Stability
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Solution Overview
Problem
In dimmable lighting systems with LEDs, the excess energy dissipation through passive resistors leads to inefficiency due to premature disconnection of triac-based dimmers, causing flicker and instability, as the power input exceeds the power output plus inherent losses, necessitating active control to maintain dimmer current above the hold current.
Innovation Solution
The implementation of active power dissipation circuits, such as switch path, flyback path, and link path power dissipation circuits, controlled by a controller to selectively dissipate excess energy during specific phases of the switching power converter's operation, ensuring the dimmer current remains above the hold current without unnecessary power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive resistors are used to dissipate excess power in the lighting system, then the dimmer current is maintained above the hold current to prevent premature disconnection, but the system efficiency deteriorates due to unnecessary power loss
Solution Approach 1:
The patent implements dynamic power dissipation control by switching between passive resistor dissipation and active circuit dissipation based on real-time detection of dimmer current levels. The controller monitors the dimmer current and selectively activates active power dissipation circuits only when needed to maintain hold current, rather than continuously dissipating power through passive resistors. This dynamic approach resolves the contradiction by making the system adaptive to actual operating conditions.
Solution Approach 2:
The patent employs a controller that automatically detects when dimmer current approaches the hold current threshold and autonomously activates active power dissipation circuits to prevent premature disconnection. The system self-regulates by using the controller to monitor current levels and selectively engage active dissipation pathways, eliminating the need for continuous passive resistor dissipation and thereby improving efficiency while maintaining reliability.
2Loss of energy
If active power dissipation circuits are implemented to selectively dissipate excess energy, then system efficiency is improved by reducing unnecessary power loss, but the device complexity increases due to additional circuit components and control mechanisms
Solution Approach 1:
The patent integrates active power dissipation circuits that serve multiple functions: they dissipate excess power when needed, and can be controlled to operate only during specific phases of the switching power converter's operation. The controller manages these multi-functional circuits to provide both power dissipation and system protection functions, reducing the need for separate dedicated circuits and thereby limiting the increase in overall device complexity.
Solution Approach 2:
The controller acts as an intermediary that manages the complexity of active power dissipation circuits by automatically detecting system conditions and selectively activating dissipation pathways. This intermediary control mechanism simplifies the user interface and system management while enabling sophisticated power dissipation strategies, effectively mediating between the added circuit complexity and the desired efficiency improvements.
3Loss of energy
If the switching power converter operates with minimal inherent power losses, then the efficiency is maximized, but the dimmer current may fall below the hold current causing premature disconnection and flicker
Solution Approach 1:
The patent implements preliminary detection of dimmer current levels by the controller, which anticipates when the current might fall below the hold current threshold. Before this occurs, the controller proactively activates active power dissipation circuits to prevent premature disconnection. This preliminary action allows the system to maintain minimal inherent losses during normal operation while ensuring reliability is maintained through advance intervention when needed.
Solution Approach 2:
The patent employs feedback control where the controller continuously monitors dimmer current levels and adjusts active power dissipation accordingly. When the monitored current approaches the hold current threshold, the feedback mechanism triggers activation of active dissipation circuits to prevent premature disconnection. This closed-loop feedback system allows the converter to operate with minimal losses while automatically maintaining the reliability needed to prevent flicker and instability.
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 prevents premature disconnection of the dimmer, maintains system stability, and enhances efficiency by actively managing power dissipation, reducing inefficiencies associated with passive resistor dissipation.
Implementation Method 1
an active power dissipation circuit to dissipate the excess energy
Data Source
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AI summary
In at least one embodiment, a lighting system includes a link path power dissipation circuit to actively and selectively control power dissipation of excess energy in a switching power converter of the lighting system. The link path power dissipation circuit dissipates power through a link path of the switching power converter by controlling a link current of the switching power converter. In at least one embodiment, the controller controls the link path power dissipation circuit to limit the link current with a current source and dissipate power in the current source. In at least one embodiment, the link path power dissipation circuit includes a switch to limit the link current and dissipate power in the link path.