LED Driver Supplementary Current Circuit for TRIAC Dimmer Stability

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Solution Overview

Problem

Silicon-controlled dimmers in LED drivers face inefficiencies due to high loss and low efficiency caused by the need for extra bus current to maintain conduction, leading to LED load flashing and reduced performance.

Innovation Solution

An LED driver with a supplementary current generating circuit that ensures the input current meets the conduction requirements of the TRIAC dimmer by determining the supplementary current based on the drive current and holding current, using transistors and controllers to adjust currents and voltages, and incorporating a bleeder circuit to reduce losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If extra bus current is added to maintain TRIAC conduction, then the conduction requirement is met, but the loss of LED driver increases and efficiency decreases

Engineering Contradiction:

Improveconduction requirementVSAvoidloss of LED driver

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

A supplementary current generating circuit is introduced as an intermediary component to provide the necessary holding current to the TRIAC. This separate current path allows the TRIAC to maintain conduction without requiring excessive bus current, thereby reducing overall energy loss in the LED driver system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The current supply is segmented into two independent paths: the main LED drive current and the supplementary holding current for the TRIAC. This segmentation allows precise control of each current component, ensuring the TRIAC receives adequate holding current while the main power path operates efficiently for LED illumination.

Inventive Principle:

Principle #1Segmentation

2Reliability

If larger constant current is maintained for LED load, then TRIAC conduction is sustained, but efficiency of LED driver decreases

Engineering Contradiction:

ImproveTRIAC conductionVSAvoidefficiency of LED driver

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The supplementary current is dynamically adjusted based on the actual operating conditions of the TRIAC and LED load. The circuit monitors the holding current requirement and provides supplementary current only when needed, rather than maintaining a constantly large current, thereby improving overall system efficiency while ensuring reliable TRIAC conduction.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If phase control method is used for dimming, then dimming function is achieved, but current ripples and LED flashing occur

Engineering Contradiction:

Improvedimming functionVSAvoidcurrent stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The supplementary current generating circuit incorporates feedback mechanisms that monitor the chopped phase output and adjust the supplementary current accordingly. This feedback control compensates for current ripples introduced by phase control dimming, maintaining stable LED operation and eliminating flashing while preserving the dimming function.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3576496B1LED driver with a silicon controlled dimmer and control method thereof

Publication Date: 2021.05.05 SILERGY SEMICON TECH (HANGZHOU) CO LTD

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AI summary

An LED driver with a silicon-controlled dimmer and a control method thereof are provided in the invention. A supplementary current generating circuit is provided on a current path of an LED load, such that an input current of the LED driver can meet conduction requirements of the silicon-controlled dimmer, thereby reducing the loss of the LED driver and improving the efficiency of the LED driver