고효율 및 고역률 LED 구동을 위한 디지털 제어기에 관한 연구

Abstract

기존 조명기기는 높은 소비 전력과 짧은 수명, 환경오염을 유발하는 등 많은 문제점을 가지고 있다. 반면에 차세대 조명기기로 주목받는 LED는 화학물질과 전기 자극에 의해 빛을 내는 반도체로써 디지털 제어 특성과 고효율, 긴 수명의 장점을 가지고 있다. 본 논문에서는 고효율 및 고역률 LED 구동을 위한 디지털 제어기를 제안하였다. 고효율을 달성하려는 방법으로서는 역률 개선과 전력 변환을 하나의 컨버터로서 구현할 수 있는 단일 단 컨버터 방식을 적용하였고, 고역률을 달성하기 위해서는 전류연속모드와 전류불연속모드 경계에서 동작하는 임계모드(BCM : Boundary Conduction Mode)방식을 선정하였다. LED 구동회로의 고역률 및 고효율 특성을 도출하기 위해 제안한 디지털 제어기법을 실제 구현하기 위하여 저가형 마이크로컨트롤러인 Microchip사의 dsPIC30F2020을 적용하였다. 제안한 디지털 제어기의 타당성을 검증하기 위하여 32W의 LED 구동회로를 제작, 적용하였으며, 실험을 통해 본 논문에서 제시한 제어기의 유용성을 확인하였다.| This paper suggests a digital controller for a high efficiency and high power factor LED driver. The digital controller was implemented by using a low-cost dsPIC. The power stage of the driver was employed by a single-stage Flyback converter which is operating in BCM(boundary conduction mode) to achieve high efficiency and high power factor. The dsPIC30F2020 of Microchip Corporation was used as the low-cost dsPIC controller. The LED driver proposed was designed that a constant current of 1A flows into LED at the output voltage of 32V for the universal input voltage range of 88Vac ~ 264Vac. The configuration of the LED module used in this research is that ten HB(high brightness) LEDs are connected in series and five of the series connected LEDs are connected in parallel. The protype LED driver was built and tested. From the experiment results it is confirmed that a high efficiency more than 85% and high power factor more than 0.9 were obtained. For the future work, a digital dimming control for the LED driver will be considered.; This paper suggests a digital controller for a high efficiency and high power factor LED driver. The digital controller was implemented by using a low-cost dsPIC. The power stage of the driver was employed by a single-stage Flyback converter which is operating in BCM(boundary conduction mode) to achieve high efficiency and high power factor. The dsPIC30F2020 of Microchip Corporation was used as the low-cost dsPIC controller. The LED driver proposed was designed that a constant current of 1A flows into LED at the output voltage of 32V for the universal input voltage range of 88Vac ~ 264Vac. The configuration of the LED module used in this research is that ten HB(high brightness) LEDs are connected in series and five of the series connected LEDs are connected in parallel. The protype LED driver was built and tested. From the experiment results it is confirmed that a high efficiency more than 85% and high power factor more than 0.9 were obtained. For the future work, a digital dimming control for the LED driver will be considered.