• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.275-283
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• 2021

In this study, a driver IC for an AC-powered LED that can be manufactured with a low voltage semiconductor process is designed and the performances of the driver IC were simulated. In order to manufacture a driver IC that operates directly at AC 220V, a semiconductor manufacturing process that satisfies a breakdown voltage of 500V or higher is required. A semiconductor manufacturing process for a high-voltage device requires a much higher manufacturing cost than a general semiconductor process for a low-voltage device. Therefore, the LED driver IC is designed in series so that it can be manufactured with semiconductor process technology that implements a low-voltage device. This makes it possible to divide and apply the voltage to each LED block even if the input voltage is high. The LED lighting circuit shows a power factor of 96% at 220V. In the pnp transistor circuit, a very high power factor of 99.7% can be obtained, and it shows a very stable operation regardless of the fluctuation of the input voltage.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.506-511
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• 2017

LED lighting, which many companies are pursuing commercialization, is a representative green energy technology. However, the LED lighting for broadcasting image should have high output and easy portability compared with general LED lighting devices for street lamps, advertisement or transportation devices. Therefore, while shooting a broadcast image if you use LEDs as a substitute light source for halogen lamps and fluorescent lamps that are large in size and uncomfortable to handle it is expected that the lightening of the equipment will activate the broadcasting image lighting equipment industry. After considering the mass production of the LED module board and the SMT production size of the chip mounter, the board size was determined considering the overall size of the product by model. In this paper, four 20W LED boards are arranged vertically in order to produce an 80W board. In other words, by sharing LED module board size by model, high power LED lighting equipments of 120W and 200W can be selected as an increase in the number of boards.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.35-42
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• 2010

This paper presents the Two-stage LED Driving system using LLC resonant converter for LED lighting application. Due to the existence of the nonisolation DC/DC converter to control the LED current and the light intensity, the conventional three-stage LED Driving system has the problem of low power conversion efficiency. To solve this problem, a novel scheme without any nonisolation DC/DC converter is proposed, in which, the isolated DC/DC converter, e.g., LLC resonant converter in the paper, can perform the LED current control and stage, e.g., PFC stage and LLC stage, the efficiency can be significantly improved. Moreover, the cost and the volume of the whole LED driving system can be reduced compared to those of the conventional ones. The operational principle and the characteristics of the proposed scheme are presented. The proposed scheme is verified experimentally with a 45W output prototype LED driver.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.2
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• pp.163-170
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• 2015

Recently LED fish-attracting lamps have been more widely used in fisheries as low-cost and high-efficiency fishing gear, and development of long-life high-efficiency lamps is required through the design of LED packages to optimize heat resistance. This study developed an improved LED fish-attracting lamp with excellent heat performance, which was verified using a numerical model. Heat-resistance design factors such as the heat-radiation fin shape, PCB type, and LED chip count were investigated and optimized. Comparison with a commercial 180-W LED fishing lamp showed that the increase in initial temperature was 40% higher than that of the surrounding LED chip because of design errors in contact thermal resistance. The 250-W LED lamp developed in this study has a characteristic with thermal rising in linearly stable according to the heat source. In addition, luminance efficiency was improved by 20-65% by using flow-visualization simulation. A decrease of 45% in total power consumption with a fuel-cost reduction of over 55% can be expected when using these optimized heat release design factors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2043-2047
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• 2010

This study is to solve problems of depletion of RF bandwidth frequency, confusion possibility, security that current wireless communications system have and is to confirm possibility of applying next generation network. To solve problems of current wireless communications system, visible light communications system for power line communications using ATmega16 Microcontroller is was realized and receiver property was analyzed. PLC exclusive chip APLC-485MA, Microcontroller ATmega16, 5pi bulb type LED and high flux LED, visible light receiving sensor LLS08-A1 were used for transmitter and receiver. Performance was analyzed by designed program and an oscilloscope. It was showed average 20% improved receiver rate rather than bulb type LED in the case of high flux LED through voltage change rate on communication distance and LED type of distance between 10 to 50 cm. The blue LED showed the best performance among measured LED types with above 10% of voltage decreasing rate. But As it gradually becomes more distant, the precise date was difficult to obtain due to weak light. To overcome these sort of problems, specific values such as changing conditions and efficiency value relevant to light emitting parts and visible light receiving sensor should be calculated and continuous study and improvements should also be accomplished for the better communications condition.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.117-122
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• 2005

최근 에너지 절약에 대한 관심이 고조되면서 기존 광원보다 효율이 좋은 광원개발이 계속되고 있으며 그 대표적 것이 고출력(high-power) LED이다. 고효율 LED의 개발로 인해 일부에서는 일반 조명용으로 사용하려는 연구가 진행 중이며 풍력과 태양광 발전을 이용한 야간 조명용 전원으로 사용하려는 연구도 진행되고 있다. 이에 본 논문에서는 조명용 광원으로 직류 전원을 이용한 고출력 LED의 사용 가능성을 확인하고자 하며 기존 방식에 비하여 보다 안정적이고 효율이 좋은 새로운 LED 전원구동장치를 제안한다. 제안된 방식은 기존의 방식에 리액터의 크기를 줄일 수 있었으며 효율이 개선됨을 확인하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.154-156
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• 2006

A few ten mW white LED can substitute for the indicator light source and it is required to study several watt multi-chip semiconductor light sources in order to replace the light sources for general illumination such as incandescent lights and fluorescent lanes. Since the optical technology used for several mW white LED light source uses only 30% to 52% of the light it is required to develop the design technology of optical system and lens to improve the efficiency more than 80% for insuring the high power of white LED. In this paper, we designed and fabricated new structure reflector to increase the efficiency and is easy to make high power multi-chip LED lamp.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.161-161
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• 2010

In order to achieve low power consumption and the uniform power spectrum of LED BLU (Back Light Unit) system, new circuits with a 2 stage L-C (Inductor-Capacitor) coupler have been proposed. From the simulation results based on our proposed model, the ripple power of the L-C regulation-embedded BLU circuit shows a dramatic reduction by more than 89.3% as compared to the normal BLU (without L-C circuits). This indicates that the proposed circuit is very promising for the realization of high-efficiency BLU circuits.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.1
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• pp.64-70
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• 2011

This paper presents a zero-transient current control method for PWM dimming of LED. Since the proposed LED current control method has no transient state, it features a high resolution, high linearity, and no current overshoot through LED along a wide dimming range. The operational principles of the proposed LED current control circuit are presented. To confirm the validity of the proposed method experimental results from a prototype circuit of the 46-inch LCD TV are given.