Current-Sharing Supply Circuit for LED Drivers

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Solution Overview

Problem

Conventional current-sharing supply circuits for driving multiple LED strings suffer from high power loss, low operating efficiency, and complex circuitry due to the use of linear regulators and current mirrors, leading to non-uniform brightness and reduced lifespan of LED strings.

Innovation Solution

A current-sharing supply circuit that includes a current providing circuit, output rectifier circuits, and current-sharing transformers with adjustable equivalent impedance values to ensure identical currents across multiple sets of DC loads, reducing power loss and simplifying the circuit configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If linear regulator and current mirrors are employed to achieve current sharing, then uniform brightness is obtained, 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 (a dissipative electrical component) with a switching regulator architecture that uses pulse-width modulation (PWM) to control current. This substitution eliminates the continuous power dissipation inherent in linear regulators, thereby reducing power loss while maintaining uniform brightness across multiple LED strings through synchronized switching control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters by using high-frequency switching instead of continuous linear regulation. The switching regulator operates in pulsed mode with duty cycle control, fundamentally changing how current is regulated and enabling much higher efficiency while achieving the same current-sharing objective for uniform LED brightness.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If linear regulator and current mirrors are employed to achieve current sharing, then uniform brightness is obtained, but circuit complexity increases

Engineering Contradiction:

Improveuniform brightnessVSAvoidcircuit complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges the current regulation function into a single centralized switching regulator that simultaneously controls multiple LED strings through shared control circuitry. This consolidation eliminates the need for separate linear regulators and current mirrors for each LED string, reducing overall circuit complexity while maintaining uniform brightness through synchronized PWM control.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The switching regulator is designed with multi-functionality to serve multiple LED strings simultaneously. The control circuit generates synchronized PWM signals that can regulate current across multiple channels, making a single regulator perform the work of multiple regulators and simplifying the overall circuit architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If multiple components are used for current sharing, then current control is achieved, but operating efficiency decreases

Engineering Contradiction:

Improvecurrent controlVSAvoidoperating efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent substitutes the inefficient linear regulator-based current control system with a switching regulator system that achieves equivalent or superior current control precision while operating at much higher efficiency. The PWM-based control mechanism provides accurate current regulation without the continuous power loss associated with linear regulation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The switching regulator maintains continuous useful action by using high-frequency switching to deliver power in controlled pulses, ensuring that the LED strings receive consistent average current. This continuous pulsed delivery achieves reliable current control while minimizing energy loss during the switching transitions.

Inventive Principle:

Principle #20Continuity of useful 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

The solution achieves high operating efficiency, minimizes power loss, and ensures uniform brightness across all DC loads, extending their lifespan and enabling their use in compact electronic devices.

Implementation Method 1

a first current-sharing transformer Ta, a second current-sharing transformer Tb... The first current-sharing circuit 22a, the primary winding coil Nap of the first current-sharing transformer Ta and the output terminals of the current providing circuit 21 are connected with each other in series

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8373304B2Current-sharing supply circuit for driving multiple sets of DC loads

Publication Date: 2013.02.12 DELTA ELECTRONICS INC(CN)

AI summary

A current-sharing supply circuit includes a current providing circuit, a first output rectifier circuit, a second output rectifier circuit, a first current-sharing transformer, a second current-sharing transformer, a first current-sharing circuit and a second current-sharing circuit. By adjusting the equivalent impedance values of the first current-sharing circuit, the second current-sharing circuit, the primary winding coil of the first current-sharing transformer and the primary winding coil of the second current-sharing transformer, the first output current and the second output current are substantially identical.