LED Driver Control Decoupled From Phase-Cut Dimming Angle

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional phase-cut dimmers provide inconsistent performance when dimming LEDs due to the LED load's diode-capacitor power supply characteristics, leading to inconsistent brightness and issues with transients and drift, which conventional power supplies fail to address effectively.

Innovation Solution

An illumination device with a microcontroller-based control circuit decouples the power delivered to the LED load from the dimmer's conduction angle, using a dual-stage power supply architecture with a slow and fast control loop to regulate the LED drive current independently of the dimmer's conduction angle, and includes damping and bleed circuits to manage power supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional phase-cut dimmer is used to control LED brightness, then the dimming function is achieved, but the brightness becomes inconsistent and transients/drift occur

Engineering Contradiction:

Improvebrightness consistencyVSAvoidoperational stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The power supply is divided into two independent stages: a first stage that rectifies and filters the phase-cut AC waveform to produce a DC voltage, and a second stage that converts this DC voltage to a regulated LED drive current. This segmentation isolates the LED control from the dimmer's conduction angle variations, ensuring consistent brightness while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A microcontroller-based control circuit acts as an intermediary between the dimmer and the LED load. It measures the conduction angle from the dimmer output and uses this information to regulate the LED drive current independently, decoupling the brightness control from the phase-cut waveform and eliminating transients and drift.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the LED drive current is directly controlled by the dimmer's conduction angle, then the power delivery is simple, but the luminance control precision is poor

Engineering Contradiction:

Improveluminance control precisionVSAvoidpower supply architecture

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control system dynamically adjusts the LED drive current based on real-time measurement of the conduction angle. The microcontroller continuously monitors the dimmer output and modifies the power supply parameters accordingly, enabling precise luminance control that adapts to varying dimmer positions and electrical conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control circuit implements feedback by measuring the conduction angle from the dimmer output and using this measurement to regulate the LED drive current. This closed-loop control ensures precise luminance control by continuously adjusting the power delivery based on actual operating conditions.

Inventive Principle:

Principle #23Feedback

3Reliability

If a single-stage power supply is used, then the device complexity is low, but it cannot effectively address transients and drift

Engineering Contradiction:

Improvetransient and drift managementVSAvoidpower supply stages

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250374400A1Illumination Device and Method for Decoupling Power Delivered to an Led Load from a Phase-Cut Dimming Angle

Publication Date: 2025.12.04 LUTRON TECHNOLOGY COMPANY LLC

AI summary

An illumination device and method are provided for controlling light-emitting diodes (LEDs). The LEDs (specifically, the LED loads) are controlled, e.g., brightness and color of the LED loads, independent of a phase-cut dimmer applied to the AC mains feeding a DC power supply. The power supply is active dependent upon the duration of a conduction angle supplied from the dimmer. The power supply, however, produces drive currents that are independent from the conduction angle by using a two-stage power supply and a relatively slow and fast control loops that are controlled through a microprocessor-based control circuit. Parameters stored in the control circuit are drawn by the microprocessor to control the two-stage power supply to produce the drive currents independent and decoupled from the conduction angle yet dependent on the controller parameters.