AC LED Light Engine Selective Current Diversion for Harmonic Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

LED lighting systems often suffer from harmonic distortion and poor power factor due to non-linear loads, leading to increased harmonic energy content and reduced energy at the fundamental frequency, which affects energy efficiency and utility costs.

Innovation Solution

The implementation of a selective current diversion method in LED light engines, where current is diverted away from LEDs in a series circuit when the excitation voltage reaches a predetermined threshold, improving the conduction angle and reducing harmonic distortion using simple, low-cost circuitry with integrated harmonic improvement circuitry on the same die as the LEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If LEDs are used as non-linear loads for lighting, then illumination efficiency is improved, but power factor deteriorates and harmonic distortion increases

Engineering Contradiction:

Improveillumination efficiencyVSAvoidharmonic distortion

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The LED lighting system is segmented into multiple parallel circuits, each with its own rectifier and current control. This segmentation allows independent optimization of each circuit's power factor and harmonic content, reducing overall system distortion while maintaining efficient LED illumination.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediary current control circuit is introduced between the AC power source and the LED load. This intermediary circuit shapes the current waveform to be more sinusoidal and in phase with voltage, improving power factor and reducing harmonic distortion generated by the non-linear LED load.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If rectifier loads are used to drive LEDs, then conversion efficiency is improved, but current waveform distortion increases

Engineering Contradiction:

Improveconversion efficiencyVSAvoidcurrent waveform distortion

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The rectifier circuit incorporates dynamic current control that adjusts the conduction angle and switching timing based on the instantaneous voltage waveform. This dynamic adjustment smooths the current waveform, reducing distortion harmonics while maintaining high conversion efficiency for LED operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The circuit parameters including switching frequency, conduction angle, and filter characteristics are optimized to minimize harmonic distortion. By changing these parameters dynamically, the system achieves low waveform distortion while maintaining efficient energy conversion for the LED load.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If simple circuitry is used for current diversion, then device complexity is reduced, but control precision over harmonic distortion may worsen

Engineering Contradiction:

Improvecircuit complexityVSAvoidharmonic distortion control

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The current diversion circuit uses the LED's own forward voltage characteristics to automatically regulate current flow. When the LED forward voltage exceeds a threshold, current is naturally diverted, providing self-regulating harmonic control without complex external circuitry or precision components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent employs simple, low-cost components such as standard diodes, resistors, and capacitors for the current diversion circuit rather than expensive precision components. This approach achieves adequate harmonic distortion control through clever circuit topology rather than expensive parts, reducing overall device complexity and cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 significantly reduces harmonic distortion and improves the power factor of AC LED lighting systems, achieving high power factor and low total harmonic distortion while maintaining efficient light output and color temperature control.

Implementation Method 1

Forward current flow through an LED may cause photons to recombine with holes to release energy in the form of light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8643308B2Spectral shift control for dimmable AC LED lighting

Publication Date: 2014.02.04 SIGNIFY NORTH AMERICA CORP

AI summary

Apparatus and associated methods involve operation of an LED light engine in which a relative intensities of selected wavelengths shift as a function of electrical excitation. In an illustrative example, current may be selectively and automatically diverted substantially away from at least one of a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level. The diversion current may be smoothly reduced in transition as the excitation current or voltage rises substantially above the predetermined threshold level. A color temperature of the light output may be substantially changed as a predetermined function of the excitation voltage. For example, some embodiments may substantially increase or decrease a color temperature output by a solid state light engine in response to dimming the AC voltage excitation (e.g., by phase-cutting or amplitude modulation).