• 전력전자학회논문지
• /
• 제19권4호
• /
• pp.320-326
• /
• 2014

In this paper, the new smart dimming algorithm which is mixed with PWM and PAM control method is proposed for reducing the power consumption of LED TV Backlight. The proposed technique is using the curve characteristics of LED forward voltage and current which is proportionally changing LED forward voltage as changing LED forward current. Therefore, each PWM and PAM control method has different LED forward voltage and current in the same brightness condition. The PWM control method adjusts the brightness of LED TV Backlight by only varying the duty ratio of PWM and constantly sustaining the amplitude of LED forward current and voltage. So, the level of LED forward current and voltage in the PWM control method is relatively high and constant regardless of duty ratio of PWM. On the other hand, the PAM control method adjusts the brightness of LED TV Backlight by directly varying the level of LED forward current. So, the level of LED forward current and voltage in the PAM control method is lowered according to the brightness level. For the above-mentioned reason, the PAM control method has the advantage of reducing the total power consumption of LED TV Backlight at the brightness condition of below 100%, compared with PWM control method. By implementing this characteristic to LED driver circuit with control algorithm in MCU, the power consumption of LED TV Backlight can expect to be reduced. The effectiveness of the proposed method, new smart dimming algorithm, CPWAM(=Conditional Pulse Width Amplitude Modulation), has been verified by experimental results.

• 조명전기설비학회논문지
• /
• 제24권4호
• /
• pp.1-9
• /
• 2010

LED구동회로및 제어회로를 개발하였다. 개발된 LED구동회로는 새로운 PWM회로를 가지고 있으며 LED열의 디밍, 전류 및 온도제어 및 통신 기능을 할 수 있다. 개발된 PWM회로는 기본적인 디지털 논리소자를 사용하여 만들어 질 수 있는 두 개의 링 발진기와 한 개의 카운터로 구성되어 있다. 부가적으로 이 회로는 온-오프 제어 모드, 비상모드, 전력절감모드를 가지고 있으며 직열통신을 이용해서 제어된다. 설계 된 PWM 발생기와 제어회로는 마그나칩/하이닉스의 디지털 공정을 이용하여 제작되었다. 제작된 칩은 LED구동장치와 제어기 보드에 장착되어 테스트 되었으며 성공적으로 동작하였다.

• 산업기술연구
• /
• 제30권B호
• /
• pp.109-112
• /
• 2010

Unlike the general lighting systems, stage lighting system requires accurate dimming control and reduction of flicker phenomenon. In this paper, we studied PWM dimming control and linear voltage level control methods. PWM Dimming is easy control and flicker phenomenon of linear voltage level dimming does not happen by experiment result. We concluded that stage lighting dimming system required to combine two techniques of the PWM and linear voltage level dimming control method.

• 드라이브 ㆍ 컨트롤
• /
• 제19권4호
• /
• pp.85-90
• /
• 2022

In this paper, a DC converter to improve the performance of Power LED system is discussed. The mathematical model of PWM converter power stage using 3-Terminal PWM cell is introduced for power LED system. A controller for DC converter system is used as a self-tunning regulator with a recursive least-squares algorithm. Minimum variance control method is used as a control law. Experiment results verified that proposed control system could improve the performance of Power LED system.

• 전력전자학회논문지
• /
• 제16권1호
• /
• pp.64-70
• /
• 2011

본 논문에서는 LED조명의 휘도조절을 위해 PWM 휘도조절시 발생하는 LED전류의 과도 상태제거를 위한 전류제어 기법을 제안한다. 제안된 LED전류 제어 기법은 과도상태가 존재하지 않으므로 휘도조절 신호의 동작 시비율이 매우 작은 영역에서도 전류 제어를 통해 낮은 휘도를 정밀하게 표현할 수 있다. 또한 전류의 Overshoot이 발생하지 않으므로 휘도를 일정하게 유지할 수 있는 장점을 가진다. 본 논문에서는 제안된 LED전류 제어 기법의 동작원리를 설명하고, PSIM을 이용한 모의실험 및 실제 46인치 LCD TV의 시작품 제작을 통해 제안된 기법의 타당성 및 우수성을 검증한다.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2011년도 추계학술대회
• /
• pp.440-443
• /
• 2011

본 논문은 LED 조명 환경에서 LED 조명 제어보드를 구성하고자 하였다. LED 조명 제어보드는 주변 밝기의 변화에 따라 LED 조명의 밝기를 제어하도록 하였으며, 본 논문에서 구성된 LED 조명 제어보드는 8bit 마이크로컨트롤러인 ATmega128을 사용하여 제어 하도록 구성 하였다. LED 제어는 주변 밝기에 따른 CdS 출력값을 입력받아 ADC값을 결정하며, 결정된 ADC값은 LED 드라이버로 입력할 PWM 파형을 결정하게 된다. 이렇게 결정된 PWM 파형에 의해서 LED 조명의 밝기 제어가 가능하도록 하였다.

• 한국전기전자재료학회논문지
• /
• 제34권2호
• /
• pp.121-125
• /
• 2021

The machine vision technology has been widely used in the industrialized nations like the United States, Japan, and EU in the various industries from the late 1980s. Machine vision inspection system mainly consists of a camera, optics, illumination and an image acquisition system. Optimization of the illumination light source is very important. This paper shows a comparison between Pulse Width Modulation (PWM) control and strobe control in driving LED lighting system for machine vision. PWM control method has problems such as a temperature rising of LED and a flickering in image measurement for inspection. In contrast, the proposed strobe control method can suppress the temperature of LED light source below 40℃. Also, it can remove the flickering problem through a synchronization between a frame grabber and a camera shutter. Finally, the strobe control method was shown to extract clearer images with a high precision compared to PWM control method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.1025-1025
• /
• 2015

본 논문에는 Flyback컨버터의 PWM방식과 조명용 LED 구동장치의 디밍에 의한 조명제어를 제안한다. 제안된 LED 구동회로는 Flyback 컨버터를 이용하여 교류 입력 전원을 직류 출력전원으로 변환되는 과정을 이해한다. 포터커플러의 역할과 그 Feedback원리 그리고 PWM방식으로 IC를 직접 제어하여 버스트 디밍을 구현하고 LED의 밝기 밝기 조절 및 불필요한 전력낭비를 예방하는데 목적을 두었다.

• 한국기계가공학회지
• /
• 제14권6호
• /
• pp.129-135
• /
• 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.

• 반도체디스플레이기술학회지
• /
• 제13권4호
• /
• pp.65-70
• /
• 2014

This paper is to improve the problem of the LED dimming control system using the conventional PWM and DAC method. The conventional PWM method controls the average current to switch dimming signal. This method generates the flicker when controlling at a low current. In order to solve the problem, this system prevents the flicker with the DAC method. The LED is lit at micro-current flowing in the LED. And offset voltage is generated in the output of the DAC when the DAC output is very low voltage as 0V. This was resolved by the voltage drop of the output voltage to construct a negative offset circuit. In addition, the LED current can't flow as set values because of overheating of FET. In order to solve the problem, the 16 bits ADC in the microprocessor is a more accurate current control receives the LED current in comparison with the set value. Therefore, the LED dimming control system proposed in this paper showed the accurate and reliable more than conventional systems.