Current-Sharing Transformer for Balanced LED String Drive

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Solution Overview

Problem

Conventional current-sharing supply circuits for LED strings suffer from high power loss and low operating efficiency due to the use of linear regulators and current mirrors, leading to uneven current distribution and reduced LED string lifespan.

Innovation Solution

A current-sharing transformer with a magnetic core assembly, primary winding coil, and multiple secondary winding coils, where the secondary winding coils are connected to DC loads through rectifier circuits, ensuring equal magnetic paths for balanced current distribution across LED strings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If linear regulator and current mirrors are used for current sharing, then uniform brightness of LED strings is achieved, but power loss increases and operating efficiency decreases

Engineering Contradiction:

Improveuniform brightnessVSAvoidpower loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent replaces the linear regulator and current mirror circuitry with a transformer-based magnetic coupling system. The transformer uses magnetic flux to couple multiple secondary windings, eliminating the need for active linear regulation components and reducing power loss through more efficient electromagnetic energy transfer.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a transformer as an intermediary device between the power source and multiple LED strings. The transformer's magnetic core and windings act as a mediator that automatically balances current distribution through magnetic coupling, replacing the need for complex active current sharing circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Illumination intensity

If linear regulator and current mirrors are used for current sharing, then uniform brightness of LED strings is achieved, but circuit complexity increases

Engineering Contradiction:

Improveuniform brightnessVSAvoidcircuit complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent replaces complex electronic control circuits (linear regulators and current mirrors) with a passive transformer-based magnetic coupling system. This substitution dramatically simplifies the circuit architecture by eliminating multiple active components, feedback networks, and control logic while achieving the same current balancing function through magnetic field coupling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Duration of action of stationary object

If unequal currents pass through LED strings, then LED string lifespan is reduced, but current sharing circuit complexity increases

Engineering Contradiction:

ImproveLED string lifespanVSAvoidcircuit complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent uses a transformer with multiple secondary windings that are magnetically coupled to a primary winding. This passive magnetic coupling system automatically equalizes current distribution among parallel LED strings without requiring complex active control circuits, feedback mechanisms, or additional switching components, thereby extending LED lifespan while maintaining circuit simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The current-sharing transformer minimizes power loss, enhances operating efficiency, and simplifies circuitry by balancing currents across multiple DC loads, thereby extending LED string lifespan and ensuring uniform brightness.

Implementation Method 1

The secondary winding coils generate AC induction currents according to electromagnetic induction between respective winding coils and the primary winding coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The rectifier circuits are electrically connected to respective secondary winding coils and respective DC loads for rectifying the AC induction currents into corresponding DC voltages

Methodology Applied

Scientific EffectRectification: Diode

Data Source

PatentUS8080947B2Current-sharing transformer and power supply circuit having such current-sharing transformer

Publication Date: 2011.12.20 DELTA ELECTRONICS INC(CN)

AI summary

A current-sharing transformer includes a magnetic core assembly, a primary winding coil and multiple secondary winding coils. The magnetic core assembly includes a main magnetic post and multiple minor magnetic posts. The primary winding coil is wound around the main magnetic post. The secondary winding coils wound around respective minor magnetic posts. The secondary winding coils are connected to respective DC loads through respective rectifier circuits. The magnetic paths between respective minor magnetic posts and the main magnetic post are equal, so that the magnitudes of currents passing through the DC loads are balanced by the current-sharing transformer.