LED Converter Primary-Side Control Voltage Compensation

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Solution Overview

Problem

Existing LED converter systems face challenges in maintaining a constant LED current due to the lack of a strict connection between primary-side current and LED current, with changes in LED voltage influenced by temperature and variations in LED configuration, which are not adequately accounted for in primary-side control methods.

Innovation Solution

The solution involves modifying the target value for the primary-side current based on measured LED voltage, using a control unit to regulate the switching regulator and storing the dependence of primary-side electrical parameters on LED voltage in a look-up table or function to achieve a constant LED current, also considering temperature as a variable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If primary-side control is used to regulate LED current, then device complexity is reduced, but LED current precision deteriorates due to lack of strict connection between primary-side current and LED current

Engineering Contradiction:
Improvecontrol circuit complexityVSAvoidLED current control precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements feedback by measuring the LED voltage on the secondary side and transmitting this information to the primary side control unit. The control unit uses this voltage information to adjust the target value for primary-side current, creating a closed-loop control system that maintains precise LED current regulation while staying primarily on the primary side

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from a fixed target value to a dynamic target value that depends on the measured LED voltage. The target value for primary-side current is adjusted based on the relationship between LED voltage and current, allowing precise control without complex secondary-side measurement circuits

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If LED voltage changes are not compensated, then control simplicity is maintained, but LED current stability deteriorates under temperature changes and LED configuration variations

Engineering Contradiction:
Improvecontrol simplicityVSAvoidLED current stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent performs preliminary action by pre-determining and storing the relationship between LED voltage and the required primary-side current target values. This lookup table or stored function allows the control unit to quickly adjust to voltage changes without complex real-time calculations, maintaining both simplicity and stability

Inventive Principle:
Principle #10Preliminary action

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 allows for precise control of LED current by accounting for LED voltage variations, ensuring a consistent LED current supply despite changes in temperature and LED configuration, thereby improving the accuracy and reliability of primary-side control.

Implementation Method 1

The resonance converter then transmits power via a galvanic barrier or galvanic barrier from a primary side to a secondary side of the galvanic barrier to supply an LED path with power

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2989862B1Constant current converter for lighting devices
Publication Date: 2019.08.28 TRIDONIC GMBH & CO KG
  • EP2989862B1 patent drawingFigure 1
  • EP2989862B1 patent drawingFigure 2~3
  • EP2989862B1 patent drawingFigure 4~5

AI summary

The invention relates to an LED converter for supplying a current to an LED path which has at least one LED, having: a resonant converter (6) with a switch regulator which has at least one switch (LS, HS), a galvanic block (7), the primary side (Lm) of which is supplied by the switch regulator and the secondary side (Lt) of which is arranged so as to conduct a current directly or indirectly to the LED series, and a control unit (9) arranged on the primary side for detecting a primary-side electric parameter, wherein the control unit (9) regulates the detected primary-side electric parameter to a desired value in order to generate a desired LED current, i.e. a desired current flowing through the LED series, by controlling the switch regulator, said desired value for the detected primary-side electric parameter being dependent on the detected LED voltage.