• Title/Summary/Keyword: High-Power LED

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Analysis of the Electrical and Optical Properties in Omnidirectional LED Bulbs by Energy Star (Energy Star 기준에 따른 Omnidirectional LED 벌브의 전기적 광학적 특성 분석)

  • Kim, Yu-Sin;Bae, Ho-June;Kim, Gi-Hoon;Kim, Hyun-Sik;Song, Sang-Bin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.9
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    • pp.750-754
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    • 2012
  • An LED (light emitting diode) has the advantages of lower power consumption, energy saving, high efficiency, long lifetime, and environmental friendliness so that it has been getting the spotlight as a next-generation light source. Thus, the application range of an LED has been extended to various fields including indoor and outdoor lighting. Recently, the high efficient LED lighting has been developed, an LED has been extended its market rapidly every year and is expected to replace the general light source within near future. In this study were measured electrical and optical properties for 6 types of LED bulbs which are being developed to replace the general incandescent lamps, and were analysed under the standard of the omnidirectional lamp required by the Energy Star.

Characterizations of Luminance for Varied LED Based Surface Lighting Designs (LED 면광원에서 패키지 수량에 따른 휘도변화 특성)

  • Lee, Tae-Hoon;Choi, Seong-Dae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.6
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    • pp.70-76
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    • 2016
  • Commercialization of surface lighting using Light Emitting Diodes (LED) has embraced the advance to Organic Light Emitting Diode (OLED) technology. This is necessary to achieve light-efficiency-improvement and longer component life. The range of application of LED lighting for both interior and outdoor lights has been gradually expanding. Automobiles and home appliances are now included. In the case of LED surface lighting in a domestic refrigerator, achieving high efficiency requires optimization of the number of LEDs in a pack. Optimization is also required in the design stage of development with regard to the conversion of the light source type from point light sources to the surface light type. This paper addresses these design problems. It presents a study of brightness variations for design solutions that differ from the existing technology in both the number of LED packages and use of Light Gathering Power (LGP) information. The intention is to facilitate production of high brightness LED surface lighting for domestic refrigerators.

A Study on How to Minimize the Luminance Deviation of AC-LED Lighting (교류 LED 조명의 빛 밝기 편차를 최소화하는 방법에 대한 연구)

  • Dong Won Lee;Bong Hee Lee;Byungcheul Kim
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.36 no.3
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    • pp.255-260
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    • 2023
  • In order to spread LED lighting, LED lighting technology directly driven by alternating current (AC) commercial power has recently been introduced. Since current does not flow at a voltage lower than the threshold voltage of the LED, a non-conductive section occurs in the current waveform, and the higher the threshold voltage of the LED, the more discontinuous current waveforms are generated. In this paper, multi-LED modules are connected in series so that the threshold voltage can be adjusted according to the number of LED modules. A small number of LED modules are driven at a low instantaneous rectified voltage, and a large number of LED modules are driven at a high instantaneous rectified voltage to lengthen the overall lighting time of AC-LED lighting, thereby minimizing the luminance deviation of AC-LED lighting. In addition, the load current flowing through the LED module is adjusted to be the same as the design current even at the maximum rectified voltage higher than the design voltage, so that the light brightness of the LED module is kept constant. Therefore, even if the rectified voltage applied to the LED module changes, the AC-LED lighting in which the light brightness is constant and the luminance deviation is minimal has been realized.

Finite Element Analysis of Residual Stress Evolution during Cure Process of Silicone Resin for High-power LED Encapsulant (고출력 LED 인캡슐런트용 실리콘 레진의 경화공정중 잔류응력 발달에 대한 유한요소해석)

  • Song, Min-Jae;Kim, Heung-Kyu;Kang, Jeong-Jin;Kim, Kwon-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.2
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    • pp.219-225
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    • 2011
  • Silicone resin is recently used as encapsulant for high-power LED module due to its excellent thermal and optical properties. In the present investigation, finite element analysis of cure process was attempted to examine residual stress evolution behavior during silicone resin cure process which is composed of chemical curing and post-cooling. To model chemical curing of silicone, a cure kinetics equation was evaluated based on the measurement by differential scanning calorimeter. The evolutions of elastic modulus and chemical shrinkage during cure process were assumed as a function of the degree of cure to examine their effect on residual stress evolution. Finite element predictions showed how residual stress in cured silicone resin can be affected by elastic modulus and chemical shrinkage behavior. Finite element analysis is supposed to be utilized to select appropriate silicone resin or to design optimum cure process which brings about a minimum residual stress in encapsulant silicone resin.

A Novel Switching Mode for High Power Factor Correction and Low THD

  • Park, Gyumin;Eum, Hyunchul;Yang, Seunguk;Hwang, Minha;Park, Inki
    • Proceedings of the KIPE Conference
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    • 2018.07a
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    • pp.210-212
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    • 2018
  • A new switching mode has been proposed to obtain high power factor and low THD in single stage AC-DC converter. The conventional voltage mode control in critical conduction mode distorts input current shape with poor THD in flyback topology. Once TRIAC dimmer is connected, visible flicker in the LED lamp is easily detected due to a lack of TRAIC holding current near the input voltage zero cross. The newly proposed method can shape the input current by providing a desired reference voltage so that low THD is obtained by ideal sinusoidal input current in case of no dimmer connection and flat input current performs good TRIAC dimmer compatibility in phase-cut dimming condition. To confirm the validity of the proposed method, theoretical analysis and experimental result from 8W dimmable LED lighting system are presented.

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Improved Single-Stage AC-DC LED-Drive Flyback Converter using the Transformer-Coupled Lossless Snubber

  • Jeong, Gang-Youl;Kwon, Su-Han
    • Journal of Electrical Engineering and Technology
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    • v.11 no.3
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    • pp.644-652
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    • 2016
  • This paper presents an improved single-stage ac-dc LED-drive flyback converter using the transformer-coupled lossless (TCL) snubber. The proposed converter is derived from the integration of a full-bridge diode rectifier and a conventional flyback converter with a simple TCL snubber. The TCL snubber circuit is composed of only two diodes, a capacitor, and a transformer-coupled auxiliary winding. The TCL snubber limits the surge voltage of the switch and regenerates the energy stored in the leakage inductance of the transformer. Also, the switch of the proposed converter is turned on at a minimum voltage using a formed resonant circuit. Thus, the proposed converter achieves high efficiency. The proposed converter utilizes only one general power factor correction (PFC) control IC as its controller and performs both PFC and output power regulation, simultaneously. Therefore, the proposed converter provides a simple structure and an economic implementation and achieves a high power factor without the need for any separate PFC circuit. In this paper, the operational principle of the proposed converter is explained in detail and the design guideline of the proposed converter is briefly shown. Experimental results for a 40-W prototype are shown to validate the performance of the proposed converter.

A Study on Hybrid Control Unit Using a Smart Control (스마트 제어를 이용한 하이브리드 형 제어장치 연구)

  • Kim, Hee-Chul
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.11
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    • pp.1093-1100
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    • 2016
  • This study is to demonstrate the superiority and stability of the solar - wind power hybrid power generation system for street lamps using super capacitor EDLC(:Electric Double Layer Capacitor). It is aiming to apply the lighting device using LED light source as the load of solar-wind power hybrid power generation system for independent power source and to develop the street light system device with high output power generation system. Unlike conventional controllers, EDLC, which is used as an auxiliary device for storing the developed power in the battery, can guarantee the high output and long life of the battery.

The Study of Ripple Reduction of the PFC CCM Flyback Converter without Electrolytic Capacitor for LED Lightings using LC Resonant Filter (LC 공진 필터를 이용한 전해 커패시터 없는 LED 구동용 PFC CCM 플라이백 컨버터의 출력 전류 리플 저감에 관한 연구)

  • KIm, Choon-Tack;Kim, Young-Seok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.4
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    • pp.601-610
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    • 2016
  • The light-emitting diode (LED) has been used in a variety of industrial fields and for general 0lighting purposes on account of its high efficiency, low power consumption and long lifespan. The LED is driven by direct current; therefore, an AC/DC converter is typically required for its use. An electrolytic capacitor is generally used for stabilizing DC voltage during use of the AC/DC converter. However, this capacitor has a short lifespan, which makes it a limiting factor in LED lighting. Furthermore, LED lighting requires a dimmable control to enable energy savings and fulfil a growing consumer demand. In this paper, the dimmable single-stage power factor correction (PFC) continuous conduction mode (CCM) flyback converter that employs no electrolytic capacitor is presented. The LC resonant filter is alternatively applied to reduce the 120[Hz] ripple on the output. And the optimum value of the LC resonant filter parameters considering both efficient and performance is analysed. Simulation and experimental results verify the satisfactory operation of the converter.

Performance Evaluation of Heat Sink for Cooling of LED Projector (LED 프로젝터 방열용 히트싱크의 성능평가)

  • Lee, Kyoung-Yong;Choi, Young-Seok;Jeon, Dong-Soon;Kim, Seon-Chang;Son, Kwang-Eun
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.1167-1171
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    • 2008
  • The flow and thermal performance of the skiving and louver fin type heat sinks for the cooling system of the small LED projector were experimentally evaluated. A small fan tester based on AMCA standards was used to control and measure the air flow rate into the heat sink. Three heat blocks were used to simulate the heat and light sources(red, green and blue) of the small LED projector. We measured the pressure drop, temperatures and input power at the specific air flow rate and discussed those results. As a result, it is found that the louver fin type heat sink has higher pressure drop and lower thermal resistance than the skiving type. From the comparison of the temperature of the heat block between skiving and louver fin type, the louver fin type heat sink was found to be more suitable for cooling the high power heat source than skiving type. The thermal performance of the fan-sink(louver fin type) system was discussed with the picture taken by a thermal video.

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Design and fabrication of a high power LED searchlight (고출력 LED 탐조등의 설계 및 제작)

  • Kim, Se-Jin;Kim, Sun-Jae;Ha, Hee-Ju;Kil, Gyung-Suk;Kim, Il-Kwon
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.6
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    • pp.737-743
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    • 2014
  • This paper dealt with a retrofit high power LED searchlight to replace conventional 1kW halogen searchlights. The design specification meets KDS 6230-1046-1 and KS V 8469. An optical lens with the beam angle of $6^{\circ}$ was used to meet the luminous intensity of 800,000cd at $0^{\circ}$ in horizontal line. Heat dissipation of the LED searchlight adopted a free air cooling type which does not use a fan or a heat-pipe. From the test results, power consumption of the prototype LED searchlight was 148W which was saved by 85% comparing a halogen searchlight of 1kW. Luminous intensity was 945,000cd at $0^{\circ}$ in horizontal line, satisfying KS V 8469. Luminous efficacy was improved by 4.7 times higher than that of the halogen searchlights. Beam angle, color temperature, and color rendering index(CRI) was $5.4^{\circ}$, 5,500K, and 70, respectively. Surface temperature of the LED searchlight was below $60^{\circ}C$ and surrounding temperature of the SMPS installed inside was below $50^{\circ}C$ which were satisfied with the IEC 60092-306.