Reduction of harmonic distortion for led loads

A waveform and network technology, applied in the field of lighting systems, can solve problems such as distorted current waveforms

Active Publication Date: 2012-07-25
SIGNIFY NORTH AMERICA CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Non-linear loads such as rectifier loads can cause distorted current waveforms

Method used

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  • Reduction of harmonic distortion for led loads
  • Reduction of harmonic distortion for led loads
  • Reduction of harmonic distortion for led loads

Examples

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Embodiment Construction

[0037] To facilitate understanding, the overall organization of this document is as follows. First of all, in order to facilitate the introduction of the discussion about each embodiment, refer to Figure 1-5 A lighting system with a full-wave rectifier topology using LEDs is presented. Second, through this introduction, reference is introduced to Figure 6-9 A description of some exemplary embodiments of a full wave rectifier lighting system employing selective shunting to improve power factor capability. Third, refer to Figure 10-13 Selective shunting applied in an exemplary LED string configured as half-wave rectification is described. Fourth, refer to Figure 14-19 , the discussion turns to an exemplary embodiment illustrating selective shunting applied in LED strings using conventional (eg, non-LED) rectifiers. Fifth, refer to Figure 20 , this document describes exemplary apparatus and methods for adjusting or testing power factor improvement in an implementation ...

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Abstract

Apparatus and associated methods reduce harmonic distortion of a excitation current by diverting the excitation current substantially away from a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level, and ceasing the current diversion while the excitation current or voltage is substantially above the predetermined threshold level. In an illustrative embodiment, a rectifier may receive an AC (e.g., sinusoidal) voltage and deliver unidirectional cur not rent to a string of series-connected LEDs. An effective turn-on threshold voltage of the diode string may be reduced by diverting current around at least one of the diodes in the string while the AC voltage is below a predetermined level. In various examples, selective current diversion within the LED string may extend the input current conduction angle and thereby substantially reduce harmonic distortion for AC LED lighting systems.

Description

technical field [0001] Various embodiments generally relate to lighting systems that include light emitting diodes (LEDs). Background technique [0002] Power factor is very important for facilities that transmit electrical energy to consumers. Of two loads requiring the same level of real power, the load with the better power factor actually requires less current from the facility. A load with a power factor of 1.0 draws the least amount of current from the facility. Facilities can provide reduced power to customers with high power factor loads. [0003] A phase difference between voltage and current can result in poor power factor. Power factor is also degraded by the distortion and harmonic content of the current. In some cases, the distorted current waveform tends to increase the harmonic power content and reduce the power at the fundamental frequency. For a sinusoidal voltage waveform, only the fundamental frequency of the electrical energy can deliver real power t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/125H05B44/00
CPCH05B33/0809H01L2924/3011H05B45/40H05B45/20H05B45/42H05B45/31H05B45/36H05B45/35H05B45/3725H01L2924/00H05B45/48H05B45/37
Inventor 兹登科·格拉卡
Owner SIGNIFY NORTH AMERICA CORP
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