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Light Intensity Behavior of LED Lamps within theThermal Stabilization Period
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.ORCID iD: 0000-0002-1819-8911
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.ORCID iD: 0000-0002-4004-0352
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.ORCID iD: 0000-0003-4074-9529
2018 (English)In: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper, Published paper (Refereed)
Abstract [en]

Visible changes in the light intensity of lamps, referredto as flicker, are quantified based on definitions such asnormalized gain factor and relative light intensity variation.However, those values also change depending on the time after anLED lamp has been switched on. An experiment has been carriedout to analyze this phenomenon. A new metric, a “thermalstabilization time”, has been proposed to identify the time toreach steady state light intensity. Although rare, the change inlight intensity can reach up to 68% during the thermalstabilization time. Consequently, acquiring data at differentintervals can lead to incorrect estimation of critical metrics.Stabilization is an essential factor that should be taken intoconsideration in LED lamps’ measurement. It is recommended bythe authors that 60-minute operation is required before acquiring data.

Place, publisher, year, edition, pages
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018.
Series
International Conference on Harmonics and Quality of Power, E-ISSN 1540-6008
Keywords [en]
LED lamps, lighting, power quality, thermal stability, voltage fluctuations
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-68920DOI: 10.1109/ICHQP.2018.8378917ISI: 000444771900106Scopus ID: 2-s2.0-85049245726ISBN: 9781538605172 (electronic)OAI: oai:DiVA.org:ltu-68920DiVA, id: diva2:1210219
Conference
18th International Conference on Harmonics and Quality of Power (ICHQP 2018), Ljubljana, Slovenia, May 13–16 2018
Available from: 2018-05-27 Created: 2018-05-27 Last updated: 2023-09-05Bibliographically approved
In thesis
1. Modelling and Interference Analysis of AC-DC Converters for Immunity to Voltage Disturbances up to 150 kHz
Open this publication in new window or tab >>Modelling and Interference Analysis of AC-DC Converters for Immunity to Voltage Disturbances up to 150 kHz
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The function of electrical and electronic equipment is challenged by the high frequency emission originated from the more use of switching-based power electronic equipment and Power line communication (PLC) signaling. Investigations have shown that interferences occur in the frequency range between 2 kHz and 150 kHz, e.g., error in smart meter reading, audible noises, performance degradation and even malfunction of the equipment. This study aims to model and analyze the interference mechanism and gain the knowledge of equipment behavior/immunity under voltage disturbance from 2 kHz up to 150 kHz, so called “Supraharmonics.”

Experimental studies were conducted on different type of AC-DC converters, LED drivers, computer power supplies, Active Power Factor Correction (APFC) circuits (pre-regulator), single stage and double stage converters such as flyback and buck topologies. AC-DC converters were exposed to Supraharmonics (SHs) according to IEC 61000-4-19. Interferences, that occur in the input voltage/current and dc-link, were observed and analyzed through a mathematical model of converter circuit. 

When the AC-DC converter is exposed to SHs, three phenomena occur that 1) the conduction and blocking time of the diodes, in the bridge rectifier circuit, are deviated, 2) intermittent conduction takes places in the beginning and of diodes conduction, 3) reverse-recovery of the diodes happen that impact the dc-link voltage of the converter. Those behaviors are verified in a functional model and validated through the experiments. It is also shown that dc-link voltage metrics, peak-to-peak and average value, are impacted when SHs are present at the terminal of the converter. Further, it is revealed that if the SHs are nonsynchronized to the power system frequency, the converter due to uneven deformation of the diode conduction /blocking time generates interharmonic currents. The generated interharmonic frequency can be precisely determined by using frequency modulation equation. Result shows that generated interharmonic magnitudes are negligible if the applied SH frequency is above 16 kHz. 

In order to quantify the impact of SHs on dc-link capacitor, an immunity model that links the intermittent conduction and the dc-link capacitor current is established, analytically. By this means, it is ensured to avoid the degradation of the dc-link capacitor’s lifetime by defining the SHs voltage limits.

The analysis and modelling studies proves that SHs at the AC-DC converter terminal can cause deviations in the function of equipment both in short term and long term., e.g., increased light intensity in LED drivers, reduced peak-to-peak voltage in dc-link, interharmonic injection and reduced estimated lifetime of the dc-link capacitor. Those impacts originates from the reaction of the diodes and non-linear circuit configuration. Functional models presented in this study are able to express the reasoning and occurrence of the impacts. Established immunity model analytically gives guidance on how immune converters can be achieved in the design stage of power electronic circuits. This study provides deep insight on how AC-DC converters behaves under SH emission. Standard committees and converter manufacturer, to achieve immune and reliable power system and equipment for the future’s systems, can use this knowledge. 

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2021. p. 100
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
AC-DC power converters, electromagnetic compatibility (EMC), high frequency disturbances, supraharmonics, switching converters, interharmonics, conducted disturbances
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electric Power Engineering
Identifiers
urn:nbn:se:ltu:diva-83485 (URN)978-91-7790-799-2 (ISBN)978-91-7790-800-5 (ISBN)
Public defence
2021-06-02, Hörsal A, Skellefteå and zoom, Skellefteå, 09:00 (English)
Opponent
Supervisors
Available from: 2021-04-06 Created: 2021-04-06 Last updated: 2023-09-05Bibliographically approved

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Sakar, SelcukRönnberg, SarahBollen, Math

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