In today's global energy shortage environment, energy conservation has become the trend of the times. At the same time, the state also vigorously advocates energy conservation and emission reduction. The end of the 2008 Beijing Olympic Games and the upcoming 2010 Shanghai World Expo will be the same with green energy conservation, which brings huge historical opportunities for the development of China's LED lighting industry. . High-power LED has the advantages of high luminous efficiency, low power consumption, long life, high stability, pure light color, good safety and strong controllability. It is gradually replacing the previous light source and is widely used in full color display. Traffic lights, car lights, background light sources, landscape lighting, special work lighting, etc., have become a new generation of green light sources in the field of lighting. According to the predictions of relevant domestic institutions, the LED lighting market in China will grow rapidly from 4.85 billion yuan in 2007 to 9.81 billion yuan in 2010, driven by the Olympics and the World Expo. Relevant experts believe that China's LED lighting industry will usher in a new development peak around 2010.
statement of problem
In general, the power of high-power LEDs is at least 1W, and currently more common are 1W, 3W, 5W, 8W and 10W. Known as the "green light source", it is moving toward high current (300 mA to 1.4 A), high efficiency (60 to 120 lm/W), and adjustable brightness. However, the luminous intensity of a high-power LED is determined by the current flowing through the LED. If the current is too strong, the LED will be attenuated. If the current is too weak, the LED will be affected. Therefore, the LED driver needs to provide a constant current Power Supply to ensure high power. The safety of LED use also needs to meet the expected brightness requirements and ensure the consistency of brightness and chromaticity of each LED. Therefore, the power source conventionally used to drive light sources such as light bulbs (tungsten filaments), fluorescent lamps, energy-saving lamps, and sodium lamps is not suitable for directly driving high-power LEDs. Driving high-power LEDs with utility power also needs to address buck, isolation, PFC (power factor correction) and constant current problems, as well as higher conversion efficiency.
At present, there are thousands of special chips on the market for high-power LED constant current driving. There are ADDtek, SITI, SCT, and China Resources Converse (PT) in the world. Supertex, Texas Instruments (TI), Maxim, the country and the United States, Zetex and other well-known manufacturers. Most dedicated chips use hysteresis converter, low voltage input range, boost, buck, PWM control, power switch can be built-in or external, output current can reach 1.5A, built-in overvoltage, undervoltage, open/short And temperature protection circuits, etc.
As shown in Figure 1, the key feature of a hysteretic converter is self-oscillation, which means that the frequency will vary with input voltage, LED current, and the number of LEDs driven. However, such converters often operate in continuous mode, which means that the inductor will never saturate and will not completely drain the current. After the MOSFET is turned off, there is still current to maintain the LED brightness. However, the disadvantage is that the impedance of the detection resistor RCS is different when the duty cycle and the frequency are constantly changing. The current flowing through the RCS is not completely consistent with the actual current of the LED, and the detection data is deviated.
Figure 1: Hysteresis converter
In the field of high-power LED lighting engineering, high-power constant-current driving power of more than 100W is required, and high efficiency and power factor are required. Currently, LED driving power supplies for E27, B22 and GU10 lamps on the market are far from meeting high power. LED lighting engineering field.
Based on strict QA and QC system, all our 36V Switching Power Supply are approved CE ROHS FCC SAA UL PSE and KC certifications. Our power supply adapters are 100% PC and brand new. Pengchu is one of the white hart for power supply business in China. Our mission is providing specialized switching power supplies for our business partner through export engineering, superior products and dependable service. And our value message is with us your business in safe and your money in safe. Hope to be your honest and trustworthy power supply vendor in China.
36V Switching Power Supply ,36V Dc Power Supply,36V Power Supply,36V Power Supply Adapter
Shenzhen Pengchu Industry Co., Ltd , http://www.pc-adapters.com