Electronic Engineering (Constant Voltage Circuit)-Prof.Kim Gi-Nam- Institute of Engineering-전자공학(정전압회로) - 김기남공학원 제공(방송기술직, 공기업 공채전문 학원)-SOUTH KOREA

Electronic Engineering (Constant Voltage Circuit)-Provided by Kim Gi-Nam Institute of Engineering

Fully-Integrated LED Drivers Using Digital Control Techniques by Kichang Jang Department of Electrical and Computer Engineering The Graduate School of the University of Seoul

Fully-Integrated LED Drivers Using Digital Control Techniques by Kichang Jang A
 Ph.D. Dissertation submitted to the Department of Electrical and Computer Engineering at the Graduate School of the University of Seoul 
in partial fulfillment of the requirements for the degree of Doctor of Philosophy June 2016 Approved by Joongho Choi Advisor

 ABSTRACTS
Most LED-lighting applications are constructed through the connection of a number of LEDs in parallel or in a series for the attainment of sufficient light. If LEDs are connected in parallel, however, an issue regarding the current-matching properties of the LEDs may arise; furthermore, if the LEDs are connected in a series, a high-voltage issue and an instability problem regarding the presence of a single open-circuit LED may also occur. Although the supply voltage varies due to the varying load condition, the current regulator maintains a constant LED current, while the employment of a switching converter can drive the LEDs for the improvement of the operating efficiency. LED drivers are still hampered by a poor operating efficiency, though, due to a voltage drop that is caused by the pass-transistor and the resistor of the current regulator. In this thesis, LED drivers that have been designed for flash-LED and LED-lighting applications are introduced; furthermore, a novel flash-LED current regulator is presented. To obtain a higher efficiency and a smaller area, the proposed regulator is operated without a resistor unlike the conventional current-regulator design. The designed flash-LED driver for which the proposed current regulator is used consists of a boost converter, an analog-to-digital converter (ADC), and a digital-to-analog converter (DAC). The boost-converter output voltage is set by an adaptive-voltage control for which the ADC and the DAC are used, and this control ensures the provision of a high-precision LED current; here, the use of the proposed LED-driver-control method provides only a 2 % current error at an LED current of 0.5 A. A higher efficiency and a smaller area are achieved through the use of a 0.13 μm-BCD process for the implementation of the flash-LED driver. A primary-side-regulated flyback converter for an LED-lighting application is also presented in this thesis. The proposed mid-current sensing circuit is introduced for the attainment of a precise outputcurrent regulation with respect to both the discontinuous-conduction mode (DCM) and the continuous-conduction mode (CCM); furthermore, a current error that is derived from an on-time propagation delay that is due to circuit imperfections is also analyzed A novel adaptive on-time-delay compensation circuit is therefore proposed for the attainment of a precise output-current regulation. The proposed compensation circuit is fully integrated for the delayerror factor; also, unlike a number of the other existing circuits, external components are not required for the proposed circuit. The LED-lighting flyback converter is implemented using a 0.35 μm- BCD process. The use of the proposed method provides only a 4 % current error regardless of the LED current that is applied
 Keywords: LED driver, adaptive voltage control, boost converter, current regulator, primary-side regulation flyback converter, mid-current sensing circuit
LINK: https://www.mediafire.com/file/c3s26xyq7fhv59w/Fully-Integrated_LED_Drivers.pdf/file

LABORATORIOS E PROJETOS DA COORDENAÇÃO DE CIENCIAS ESPACIAIS -CEA-INPE-INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS -BRASIL

LINK https://youtu.be/HHztrhZvJ64

New China-Brazil earth resource satellite sent into space-CBERS-4A launch-PARCERIA BRASIL CHINA

CBERS-4A LAUNCH 

Etapa Final de Testes do Satélite Sino-Brasileiro - CBERS-4A
PROGRAMA BRASIL COM CIENCIA HISTORIA DE 30 ANOS DE PARCERIA BRASIL CHINA EM DESENVOLVIMENTO DE SATELITES
TAIYUAN, Dec. 20 (Xinhua) -- A new satellite, jointly developed by China and Brazil, was sent into space on Friday, pushing forward the aerospace cooperation between the two countries, according to the China National Space Administration (CNSA).

 The China-Brazil Earth Resource Satellite-4A (CBERS-4A) was launched on a Long March-4B carrier rocket at 11:22 a.m. Friday Beijing Time from the Taiyuan Satellite Launch Center in north China's Shanxi Province.

 The satellite is the sixth satellite under the earth resource satellite cooperation program between the two countries. It will obtain global optical remote-sensing data and support the Brazilian government's monitoring of the Amazon rainforest and the country's environmental changes.

 The CBERS-4A will replace CBERS-4, which was launched in 2014, to improve the resolution of the remote-sensing data, said CNSA. It is equipped with three optical payloads: a wide-range panchromatic multispectral camera developed by China, and a multispectral camera and a wide-field imager developed by Brazil. It has a better imaging capacity and higher positioning accuracy than CBERS-4, and can better meet the urgent needs of both countries in land and resources exploration, land classification, environmental protection monitoring, climate change research, disaster prevention and mitigation, crop classification and yield estimation, according to CNSA. It can also provide services for Asian, African and Latin American countries. In July 1988, China and Brazil signed the agreement establishing the joint research and production of the earth research satellites. The first such satellite was launched from China in 1999. Brazilian Minister of Science, Technology, Innovation and Communications Marcos Cesar Pontes said the cooperation between China and Brazil has contributed to international economic and social development. He said the new satellite will be used in fields such as earth resource monitoring, agriculture, meteorology, environmental protection, surveying and mapping, and serve Brazil and more developing countries.

Low Cost Drive Circuit and Control IC Design for AC-Direct LED Lamps-Doctoral Thesis Yoo-Chae Chung (정 유 채) Department of Electrical Engineering Pohang University of Science and Technology

Low Cost Drive Circuit and Control IC Design for AC-Direct LED Lamps-Doctoral Thesis Yoo-Chae Chung (정 유 채) Department of Electrical Engineering Pohang University of Science and Technology

 Abstract
This paper proposes a drive circuit for ac-direct LED lamps and its custom IC design. The proposed circuit consists only of a line filter, an LED bridge, a load inductor, a bi-directional switch, and a switch-control circuit. The switch connects the LED bridge to the power line directly. Each leg of the LED bridge consists of LEDs and a protection diode, all connected in series. The load inductor limits the bridge current. The switch operates at a zero current switching condition, so the circuit has high power efficiency PE. The circuit can operate at a free-volt input condition (85 < Vin,rms < 265 V). For all input voltage conditions the circuit had PE > 89%, luminous efficiency ~ 90 lm/W, power factor > 0.9 and 120 Hz flicker index ~ 0.3. The circuit satisfies the IEC 61000-3-2 Class C and the EN 55015 regulations. The proposed LED driver is wellsuited for use in household LED lamps.
LINK
https://www.mediafire.com/file/9g9cnq4x5nsm7ch/Low_Cost_Drive_Circuit_and_Control_IC_Design_for_AC-Direct_LED.pdf/file