• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.2003-2008
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• 2012

A drive system is necessary to operate LED by an LED illumination system. Because Switched Mode Power Supply (SMPS) is higher in efficiency in the large capacity than Linear Regulator, it is used mainly and controls this in an analog form or digital method. A MCU and a DSP of the digital control central processing unit were higher in a unit price than existing analog control chip, so that an approach was not easy for application of SMPS. But it can take the earnings by it lets you integrate various digital control features like an LED illumination system in one MCU, and realizing a whole system. In this paper, we suggest the algorithm that can improve LED driving current in applying such a digital control method using low-priced type MCU.

• Journal of Applied Reliability
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• v.18 no.1
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• pp.8-19
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• 2018

Purpose: This study has developed the accelerated lifetime test method for smps for outdoor lighting LED through two factors of temperature and humidity. Methods: Acceleration condition was confirmed for each stress and model, and acceleration life test model was estimated according to acceleration condition. Results: As a result of confirming the accelerated life test model, in the case of humidity, acceleration was established only in the foreign products. Therefore, it is confirmed that the acceleration condition is insufficient. However, the estimated parameters for temperature are relatively constant. It is therefore suitable for power supply acceleration tests for outdoor lighting LEDs. Conclusion: The SMPS acceleration test for outdoor lighting LED can improve the availability of the product by developing an accelerated life test method that guarantees the reliability of the product.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.129-135
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• 2015

This paper shows significant methods that improve the lifespan of LED modules as well as efficiently using an aluminum heat-sink for LED module in high power. It proposes a method that raises stability and lifespan to protect LED modules and the power unit when the LED module has been used for a long hours at high temperatures. During the research, we applied a method of pulse-width modulation (PWM) in order to prevent the phenomenon that the entire power of a system is turned off and the lifespan is reduced when the LED nodule reacts to the high temperatures. To protect the LED module and SMPS based on high efficiency, a temperature sensor is attached underneath the circuit board and the sensor measures the temperature of circuit board when the LED module is powered on. The electrical power connected to SMPS is controlled by PWM when the temperature of the LED module reaches a particular temperature.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.95-100
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• 2007

Channel letter용 High Power LED Module 개발하기 위하여, 1W 백색(단색) LED 1EA LED Module과 1W 백색(단색) LED 3EA LED Module, 3W RGB LED 1EA LED Module에 대한 3종의 제품 개발하고, 고효율 RGB LED SMPS 회로 설계, 광색 가변을 위한 RGB LED 최적 배치 및 렌즈 설계, 고출력 1W LED Module 방열 설계 및 기구 개발, SMPS 회로 및 RGB LED 배열 회로 통합 시제품 직접 제작하였다, 신뢰성 평가 및 성능 시험 등을 실시하였으며, T자형 Channel letter에 기존 고휘도 LED Module과 개발된 고출력 LED Nodule을 동시에 적용한 결과, 기존 고휘도 LED Module를 사용하였을 경우에는 $1W{\times}10$개로 10W의 전력을 소비하였으나 개발된 고출력 LED Nodule은 $3W{\times}3$개로 9W의 전력을 소비하였으며 1W의 에너지가 절감되었음에도 불구하고 평균 휘도는 약 2.5배, 균제도는 1.43 배가 더 우수한 결과를 얻었다.

• Journal of IKEEE
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• v.18 no.3
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• pp.335-340
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• 2014

Recently, LED (Light Emitting Diode) becomes to be useful to apply for the lightening sources in electric systems and the lightening equipment since the power is less consumed with high efficiency, and the size and the weight of LED are small and light, respectively. The LED is controlled with constant current and SMPS (Switching Mode Power Supply). It is necessary for the LED manufacturer to secure the fundamental technology of designing LED chip, and to study the methodology to improve the power factor (PF) and to design the operational circuit for the development of LED to reduce the power loss in the application of LED lightening. The direct AC (Alternating Current) LED driving circuit, HV9910, is widely used in the industry field. In this paper, it is to evaluate the improved methodology for the power factor and efficiency through simulations when PFC (Power Factor Correction) and Noise Filter are added to HV9910.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.32-43
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• 2014

This paper presents the intra capacitance modeling according to the winding method, section bobbin and coil structure for hybrid choke coil capable of the EMI attenuation of broad bands from lower frequency bands to higher frequency bands and high frequency type common-mode choke coil capable of the EMI attenuation of high frequency band used in the EMI Block of LED-TV SMPS. In case of high frequency type CM choke coil, it can be explained the parasitic capacitance of A type and section bobbin type winding methods among them is much smaller than the other. The first resonant frequency of the proposed CM choke coil tends to increase as the parasitic capacitance becomes small and its impedance characteristics also show improved performance as the first resonant frequency increases. In case of hybrid choke coil using rectangular copper wire, it has investigated its parasitic capacitance compared to CM choke coil of conventional toroidal type becomes small. Also it has confirmed through the experiment results that CE margin and RE margin in frequency bands 0.5MHz to 5MHz and 30MHz to 200MHz are respectively 10dB and 15dB greater than that of conventional type in case of one stage EMI filter structure adopting hybrid choke coil compared to two stage EMI Filter structure using two of each CM choke coil used in the lower and higher frequency bands or two of CM choke coil used in only the lower frequency bands. In the future, the hybrid choke coil and CM choke coil of high frequency type show it can be practically used in not only LED/LCD-TV SMPS but also several applications such as LED Lighting, Laptop Adapter, Server Power Supply and so on.

• Journal of IKEEE
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• v.22 no.1
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• pp.185-188
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• 2018

This paper describes the parasitic capacitance modeling according to the coil structure, section bobbin and winding method for hybrid choke coil with reduced parasitic capacitance capable of the EMI attenuation of broad bands from lower frequency to higher frequency applied in the EMI attenuation filter of LED-TV SMPS. Especially, the hybrid choke coil with reduced parasitic capacitance($C_p$) proposed in this paper can reduces the parasitic capacitance($C_p$) by adopting the winding methods of rectangular copper wire, compared to the conventional common mode choke coil with the winding method of automatic type. The first resonant frequency of the proposed hybrid choke coil has a tendency to increase as the parasitic capacitance is smaller and its impedance characteristics, especially in the high frequency bands, improves as the first resonant frequency increases. In the future, the proposed hybrid choke coil with reduced parasitic capacitance shows it can be actually utilized in not only LED-TV SMPS but also various applications such as LED Lighting, Note-PC Adapter, and so forth.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.8-14
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• 2014

This paper presents the intra capacitance modeling according to the winding method and section bobbin for CM choke capable of the EMI attenuation of broad bands from lower frequency bands to higher frequency bands and high frequency type common-mode choke capable of the EMI attenuation of high frequency band used in the EMI Block of LED-TV SMPS. In case of high frequency type CM choke, it can be explained the parasitic capacitance of A type and section bobbin type winding methods among them is much smaller than the other. The first resonant frequency of the proposed CM choke tends to increase as the parasitic capacitance becomes small and its impedance characteristics also show improved performance as the first resonant frequency increases. In the future, the CM chokes of high frequency type show it can be practically used in not only LED/LCD-TV SMPS but also several applications such as LED Lighting, Adapter and so on.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.74-77
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• 2011

PSPICE modeling of a commercial LED driver IC (TOP245P) and PC817A optocoupler is proposed for the switch-mode power supply (SMPS) (applicable to LED driver) design and simulation. An analog behavioral model of the TOP245P IC including the shunt regulator, under-voltage(UV) detection, over-voltage(OV) shut-down and SR flip-flop is developed by using PSPICE. The empirical equation of PC817A current transfer ratio (CTR) is fitted from the datasheet of PC817A. Two types of SMPSs are simulated with the averaged-model and switching-model. The simulation results by the proposed PSPICE models are in good agreement with those in the data sheet and an experimental data.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.155-156
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• 2012

본 논문은 역률과 고조파 규제를 만족하는 새로운 형태의 수동형 LED 구동회로를 제시한다. 제안된 수동형 LED 구동회로는 능동형(SMPS 방식) LED 구동회로에 비하여 초장수명과 고효율 특성을 가진다. 특히 능동형 LED 구동회로 내부의 능동소자(스윗칭 소자)로 인한 짧은 수명 및 효율 감소를 수동소자만을 사용하여 효과적으로 해결하여, 역률은 0.98, 입력전류의 총 고조파 왜율은 16%, LED 드라이버의 효율은 95% 이상임을 확인하였다. 본 논문에서는 제안된 수동형 LED 구동회로의 설계 과정을 소개하며, 이론과 실험을 통해 그 우수성을 입증하였다.