LED Drive Power Saving Technology Development Trend

In facility agriculture, artificial light sources commonly used are fluorescent lamps and high-pressure sodium lamps. In recent years, with the development of optoelectronic technology, the brightness and efficiency of light emitting diodes (LEDs) have also been greatly improved, making the use of such light sources in facilities and agricultural production become feasible, especially for closed and regulated agricultural environments (such as Plant factories, tissue culture rooms, plant growth boxes, etc. are very suitable artificial light sources. For this reason, this article mainly introduces the application and development trend of LED in facility agriculture.

The city landscape lighting pursuit is not the brightness, but the creative design of the art, LED products should be able to find its place. LED with small light emitting angle has strong directionality and can be used as local key lighting. Adding scattering agent to the packaging material can achieve a 175 degree light emitting angle suitable for lighting in a wide range. The problem is that the construction unit in urban night lighting is too high Brightness is difficult to provide designers with a large enough range of choices. At present, LED light sources commonly used in urban nightscape lighting projects include: linear lighting fixtures, decorative lawn lamps, landscape lamps, bulbs, underwater lamps, ground lamps and lanterns: underground lamps. , Glowing tiles, stone lamps, LED lamps that use solar cells as energy sources.

International LED medical application research work began in the 1990s. In 1993, the NASA first proposed LED biomedical application research. His research includes: using LED to soothe astronauts to relieve fatigue, treat wounds, use photodynamic therapy for tumors and eliminate skin inflammation, ulcers, promote wound healing, facial rejuvenation, wrinkle removal, plaque removal, treatment of acne, etc. . Israel and the United Kingdom have also launched the results of LED medical applications. Through a large number of clinical practices, experts from various countries in the biomedical field agree that LED medical devices are currently the best alternatives to He-Ne lasers for phototherapy, and they have extremely broad development prospects in medical applications. Therefore, the design of the LED circuit is particularly important, without driving the LED can never send light. LED used by each manufacturer is the same, the difference lies in the difference of the drive circuit, good drive circuit can make it work longer, play more role, save more energy, LED compared to ordinary incandescent Lamps use less electricity, but they can emit the same light, and their service life is longer. It is precisely because of the high performance and high quality of the circuit that LED can play its historic role. It will serve us well and make good for the country. For the benefit of mankind.

First, the research status and development trend at home and abroad (1) The status quo of foreign LED circuit development. The research and development of semiconductor lighting technology has attracted the attention of global research institutions and companies. A total of nearly 200 companies abroad have participated in the development of GaN devices, materials and equipment. Nearly 300 universities and research institutes have participated in the research and development of GaN. At present, the luminous efficiency (luminous efficiency) of a power-type white LED has reached 100 lm/W, and the research level has reached 160 lm/W. After technological development and market competition, the world's major LED manufacturers have formed their own technical characteristics. Nichia Chemical is at the leading position in the global technology industry, monopolizing the market for high-end white, blue and green LEDs, Toyota synthesis at the international front end for the development of white LED and headlight lighting technology, and Cree's growth of GaN epitaxial wafers on silicon carbide substrates. The traditional lighting giant Philips Absolutely holds the lead in the United States Lumileds power-based white LED; the traditional lighting giant Osram Osram Holdings's OSRAM Opto Semiconductors power LED package and automotive Led Lighting development leading internationally.

(2) Development status of domestic LED circuits. The domestic epitaxial wafer growth technology mainly comes from the United States, basically imported organic metal chemical vapor deposition (MOCVD) equipment, these equipment is not a first-class equipment in the United States, in the entire LED industry epitaxial wafer growth, chip, chip package In the three links, the growth of the epitaxial wafers accounted for 70% of the total, and the cost of the epitaxial wafers accounted for 70% of the finished products. At the same time, there was a shortage of epitaxial wafer growth technology in the world. In short, the level of the epitaxial wafers determined The entire LED industry level, the domestic company has also introduced more than 50 MOCVD equipment in succession in recent years, all dealing with large-scale production process exploration phase, once the technology is mature, it will increase the number of equipment 10 times to form a large-scale production, the market demand is huge.

The National “863” Program and the Information Industry Development Fund timely supported the research and development of domestic epitaxial devices such as liquid phase epitaxial furnaces and MOCVD equipment (The 48th Institute of Semiconductors, Chinese Academy of Science and Technology, Zhongdian Technology Group Corporation). Technological reinvention and other measures have filled the gaps in the domestic market and have made breakthroughs in the bottleneck of the equipment that has long constrained the development of China's LED industry. With the start of the national lighting project, the huge demand for domestic LED chip equipment once again caused a positive response from foreign semiconductor equipment manufacturers, they are increasingly attaching importance to China's huge market, but there is also a hidden worry in this, foreign chip equipment is high The price has relatively restricted the scale and industrialization of domestic enterprises, and has also consumed a large amount of valuable foreign exchange in the country. It also squeezed the development space for domestic equipment manufacturers.

Second, LED drive power technology development trend The rise of the LED industry, not accidental, but under the conditions of the entire scientific development, under the call for energy conservation and environmental protection, in the increasingly tense human energy situation developed. The waste and consumption of energy will inevitably call for the birth of new energy-saving products. Even if it is not LED, it is replaced by other similar products. Therefore, the rise of led lighting is inevitable. As the core driving force of LED lighting, the development of LED driving power directly affects the popularity and popularity of LED. How to reduce the cost of LEDs and allow LED lighting to enter millions of households is an important issue facing all LED people. It is also a major development opportunity.

Where will LED power supply develop in the future? We all know that the LED drive power supply directly to the LED, the equivalent of the engine. The development of LED drive power technology is crucial to the development of LED related industries. It is also decisive. The main function of the LED driving power supply is to convert the AC voltage into a DC voltage and complete the matching with the voltage and current of the LED at the same time. As the silicon integrated circuit power supply voltage goes down linearly, the LED operating voltage is increasingly in the optimal range of the power supply output voltage. Constant current and constant voltage technologies will become more and more common.

(1) Develop a series of constant voltage and constant current control electronic circuits based on the characteristics of LEDs. Use integrated circuit technology to control the input current of each LED at the optimal current value, so that the LED can obtain a stable current and produce the highest output luminous flux. . LED drive power is best able to control the size of the LED current in the event of changes in the input voltage and ambient temperature and other factors.

(2) The LED drive power supply has an intelligent control function so that the load current of the LED can be controlled at a pre-designed level under the influence of various factors. When the load current changes due to various factors, the primary control IC can control the switch to return the load current to the initial design value.

(3) In the control circuit circuit design, it is necessary to develop three aspects of centralized control, standard modularization, and system expandability.

(4) In the current situation of limited LED light efficiency and luminous flux, give full play to the characteristics of LED color diversity, and develop control circuits for color-changing LED lighting.

In 2011, the pace of development of the LED industry was less than expected, and the prices of sapphire substrates and LED chips continued to decline since the beginning of the year. The average decline in the first seven months exceeded 20%. At the upstream end of the LED industry, the project production capacity of sapphire substrates under construction amounts to 10 million pieces per year, while China’s current actual demand is only 6.85 million pieces, which is still less than 1/10 of the production capacity.

This reflects the current development difficulties faced by the LED industry. National Semiconductor Lighting research and development analysis, said LED upstream manufacturers have some excess capacity, while the mid-stream downstream application market is not as good as expected, leading to continued decline in the price of LED products, some small and medium-sized LED companies face the plight of survival.

Analysis of domestic and foreign industrial development policies, LED lighting are no doubt on behalf of the future direction of lighting, with the introduction of a series of support policies, and a comprehensive innovation of technology, ideas, LED industry will start explosive growth in the next three to five years mode.

How big is the LED industry market cake? When can we really grow? This is the issue that LED people are most concerned about. According to the “Twelfth Five-year Plan” development goal, LED lighting will occupy more than 30% of the domestic market share, and the output value is expected to reach 500 billion yuan. According to the latest news, the "12th Five-Year" special plan for semiconductor lighting will be introduced in September this year. By then, many questions will be revealed.

What is the concept of 500 billion? Turning over the information, last year China's LED application output value exceeded 100 billion yuan, which is equivalent to four to five times the LED output value in the next three to four years. This is a conclusion drawn from the dual analysis of national policies and market conditions. The possibility of realization is very great. On the domestic LED industry will form a great push, many companies will usher in explosive growth.

The optimistic expectations for the LED market are more due to the energy-saving effect of LED products. Taking a 10 watt LED lamp instead of a 60 watt incandescent lamp as an example, 0.05 kWh can be saved per hour, saving 183 kWh per year. Each Chinese person uses an LED light instead of a 60-watt incandescent lamp, which can save 183 kWh/year x 1.3 billion renminbi = 277.9 billion kWh/year, which is equivalent to the power of three Three Gorges hydropower plants.