Classification of various types of electromagnetic valve characteristics, the working principle described

solenoid valve Model Selection

applicability
● Tube Road in the fluid must be led perimeter displays in the calibration of the electromagnetic valve series of medium consistency model.
● fluid temperature must be less than the calibration temperature of the solenoid valve used.
● solenoid valve allows the liquid viscosity generally 20CST less than 20CST should be specified.
● Working pressure, maximum pressure in the pipeline should be used, such as less than 0.04MPa, 2W, ZQDF, direct-action 2011 sonata dvd ; minimum working pressure greater than 0.04MPa when the pilot can use (differential pressure) solenoid valve; maximum working pressure should be less than the maximum calibrated pressure solenoid valve; generally are one-way solenoid valve work, so pay attention to whether there is anti-pressure, check valve, if installed.
● Fluid cleanliness is not high in the solenoid valve should be installed before the filter media requirements for the general cleanliness of the solenoid valve is better.
● attention to flow and take over the aperture diameter; solenoid valve generally only two control switches; conditions permit, please install the bypass pipe, ease of maintenance; a water hammer phenomenon to customize the solenoid valve opening and closing time adjustment.
● pay attention to environmental effects of temperature on the solenoid valve.
● supply current and power consumption should be selected according to the output capacity of the power supply voltage of about ± 10% is generally allowed, must pay attention to the exchange value of the higher starting VA.
reliability
● solenoid valve normally closed and normally open into two kinds; generally used in the normally closed type, power on, power off; but on a very long time off To use a normally open type.
● life test, type test items are generally factory, or rather one country has not the professional standard solenoid  buy full lace wig , so use caution when solenoid valve manufacturers.
● action is very short at higher frequencies is generally selected direct-acting, rapid series of large-diameter selection.
security
● general solenoid valve is not waterproof, when the conditions are not allowed to use water-based, factories can be customized.
● The maximum calibration solenoid valve must be more than nominal maximum pressure within the pipe, otherwise life will be shortened or have other unforeseen circumstances.
● corrosive liquids should be used in stainless steel type, corrosive fluids should use plastic Wang (SLF) solenoid valve.
● explosive environment must use the appropriate explosion-proof products.
economy
● solenoid valve via a lot of generic, but meet the above three points should be chosen on the basis of the most economical product.
solenoid valve structure principle

direct-acting solenoid valves
are normally closed and normally open type two kinds. Normally closed when the power was off, when the electromagnetic force generated when the coil is energized, the moving core to overcome the spring force with static core pull directly on the valve, the medium was access; when coil power electromagnetic force disappears, an iron core under the action of the spring force of the reset, close the valve directly to the mouth, medium barrier. Simple structure, reliable action, at zero pressure and micro-vacuum work. Normally laptop bag on the contrary, such as less than the diameter of φ6 flow solenoid valve.
step direct-acting solenoid valves
open the valve using a valve and open valve connected to the second one, the main valve and pilot valve step by step so that the electromagnetic force and the direct pressure open the main valve port. When the coil is energized, the electromagnetic force to produce dynamic and static core core pull, the pilot valve and pilot valve port open port located on the main valve port, and the moving core together with the main valve, then the main valve the pressure chamber through the pilot valve port unloading, the pressure difference and the electromagnetic force, while under the effect of the upward movement of the main valve, open the main valve media circulation. When the coil power electromagnetic force disappears, the power core and the weight and spring under the effect of pressure off the main valve, medium stop. Reasonable structure, reliable operation, when the zero-pressure work, reliable, zero pressure at work when reliable. Such as: ZQDF, 2W.
indirect pilot solenoid valve
This series solenoid valve spool by the pilot valve and main contact with the formation of channel combinations; normally closed when without power, was closed. When the coil power competition, produced by the moving core and static magnetic core pull, the pilot valve port open, the flow of exports to the media, this time the main valve to reduce pressure on the chamber, the pressure is lower than the import side, the formation of pressure to LED ceiling light spring up along the resistance movement, to achieve the purpose of opening the main valve port, media circulation. When the coil power, the magnetic force disappears, moving core in downward movement under the action of spring force to close the main valve port. Open-type principle of just the opposite. Such as:, DF (φ15 or more diameter), ZCZ, etc.
(This article Source: mechanical expert network)

Based on the actual hardware industry to go to upgrade road

the author: Please tell us about the status of Yongkang hardware industry.
Yongkang Yang, deputy mayor of the early floor: history, handicraft developed Yongkang hardware, metal product led waterproof Switching Power Supply renowned. There is a saying called "metal craftsmen take the square, separated from the county health prefectural government," is its vivid portrayal.
reform and opening up, the rapid development of Yongkang hardware industry, has successfully opened a hardware industry as the characteristics of individual and private economy as the main economic development. Nearly ten thousand industrial enterprises in the city's existing hardware, number of employees more than 30 million people, has gradually formed car industry, doors, glass industry, power tools, kitchen appliances, leisure equipment, technical equipment, metal materials, hardware eight industries, we It is summarized as "three plus three industry preparation." Yongkang (LED spot light Wuyi, Jinyun) metal industry cluster is included in Zhejiang provincial government transformation and upgrading industrial clusters demonstration zone one. Recently, "Yongkang Hardware" also on behalf of Jin Yong Mo metal industry cluster demonstration zone, was selected as the first batch of six industrial clusters in the province of regional international brands pilot.
author: Yong Kang has over 10 000 hardware companies, faced with increasingly complex economic environment and resource constraints elements gradually increased, the Government how to promote industrial restructuring and upgrading?
Yongkang Yang, deputy mayor of the early F: Yongkang faced with resource constraints and other factors of land, industrial land has been very tight. To this end, firmly establish the three concepts: first, to the concept of space to land. Introduced a zero-growth industrial land management practices applied to technology projects, and guide enterprises through the plant conversion and layer, internal land consolidation and other ways to improve space utilization and productivity, and labor-intensive part of the project reached 10,000 square meters of land of enterprises, do need to improve the living facilities building size, the building height can reach 60 meters. Second, the concept of the technology to land. Enterprises to raise the level of equipment, increase productivity, accelerate new product development, increasing added value of products in the same land to produce more products, create more value, but also effective in reducing labor costs and reduce safety accidents . Third, the concept of land to management. Promote the meticulous management, setting up new business investment to start the bottom line, the development of recycling economy, limit the blind expansion of production enterprises, and strictly limit the high energy consumption, high pollution industry production.
accelerate economic and social transformation and upgrading in the new era, the government focused on promoting industrial restructuring and upgrading to grasp a few paths: to enhance the industry, we lock the car, "Yong Kang Manufacturing." To public Motors as the leading three companies formed a strategic alliance of new energy vehicles, more than 100 leading auto parts enterprises, is accelerating the pace of industrialization. On the basis of security, we focus on the construction of the "Ten center." Continue to build the  handbag online economy, building the headquarters and logistics center, exhibition center, clearance centers, innovation centers and hardware Industrial Hardware Design Center and other "top ten center." For the majority of enterprises to provide public service platform, especially in the field center Yongkang producer services as a gathering area, will be Yongkang hardware transformation and upgrading of industrial clusters to achieve an important carrier. Technical support, we guide the enterprises' technological transformation of scale. " Great efforts to "zero growth in technical innovation," encouraging "not by half an acre of a subdivision, still turning to mention the quality benefits." For industrial investment this year, 6.4 billion new provincial high-tech R & D center 2, 10 high-tech enterprises. Enterprises through technological innovation not only increased production, stable quality, but also effectively reduce the labor intensity and density. In primary research, we note that there is a business thus reducing the accident rate by three quarters. Support of the project, we actively carry out the "central enterprises butt." The city's leading group of the central enterprises to establish docking, the establishment of clusters do, cars run, central enterprises butt to do. In recent years, has seven times the rate associated with the central business enterprises docking program, and in the automotive, high-speed rail, nuclear power, National Grid and other areas to achieve a breakthrough. In the management of innovation, we nurture enterprise "market share reform." Completed this year, five joint-stock companies, the first listed company following the September - "Hals", the "Dominion optical" on November 22 successfully landed small plates, listed in Shenzhen Stock Exchange. We also established a docking Province Property Exchange Exchange led running text Zhejiang sub-centers and the opening run. In the development environment, we strive to create "financial ecology." In recent years, Chouzhou, Industrial, Investment, CITIC Bank and other seven settled, the formation of a variety of financial institutions the coordinated development of diversified financial services organization system. Established system of government bank and the association, the association will meet regularly to government bank and to promote cooperation between banks. Establishment of key business capital chain security information submitted to the system, strengthening early warning and control financial risks.
other hand, the hardware is different from the chemical industry, pharmaceutical industry, its development requires many years to cultivate. For example, to form a chain of associations, technology, talent accumulation, corporate culture, precipitation, etc., within a short time difficult to achieve quality improvement. We proceed from reality, the first company to promote the accumulation of capital, and many other equipment and processes and the transformation of savings capacity and then attempt to transformation. In layman's terms, by product, industry, constantly upgrading, and then achieve the gorgeous transformation.
this end, we change the kind of simple grasping the annual production target of corporate management, and actively guide enterprises into stock reform, technical innovation and production automation, equipment modernization, equipment, intelligence and other "two instead of three" and and to the related enterprise departments, the town (streets, districts) issued a more specific assessment indicators, corporate year-end appraisal evaluation, in addition to value, taxes and other indicators, but also to labor productivity, energy consumption, new equipment, management innovation and other indicators , into the industrial economy of the government to take "process management."
we adhere to sub-industry GMC car dvd gps and equipment to promote on-site meetings held from time to time, by the letters and included in the annual department's commitment to support business objectives, to encourage enterprises to introduce modern, intelligent, automated equipment and processes. Since May, aluminum die-casting company by industry organizations, and door industry, business executives, respectively, in the spring Haotian Group and held the door industry, technology and equipment to promote on-site meetings in key industries, modernization of production and promotion of enterprise information automation of manufacturing and testing practices, for 20 implementation of sophisticated home management of these enterprises.
author: Yong Kang, "the first upgrade, after the restructuring," the development of the road, as well as what kind of blueprint?
Yongkang Yang, deputy mayor of the early F: We will hand the transformation of traditional industries to enhance the hardware, on the one hand the cultivation of strategic development of new industries, to promote Yongkang hardware industry to a higher ladder to climb.
to accelerate the development of leading enterprises. Our goal is to strive to 2015, the city's number of listed companies reached 5, 50 billion yuan of direct financing, the new 3-5 provincial key enterprises, fostered 10 3 billion yuan output value of scale leading enterprises, fostered a net profit of over 10 billion high-growth companies.
upgrade hardware to focus on regional characteristics industry, the construction of an international Yongkang Door lady's handbag Center, China Leisure Sports car industry center, high-end small appliances and kitchen appliances production base, advanced production base of industrial scales, middle and high side insulation glass production base. At the same time, we should vigorously develop economical automotive industry, to accelerate the development of specialized manufacturing equipment, new breakthroughs in the development of special materials industry, actively develop new energy industries. Yong Kang Jiancheng strive to advanced global manufacturing base for daily-use hardware, daily hardware industry center of China, China's economic environment-friendly automobile manufacturing base in the country and the world strive to achieve "Seven right to speak": the market share of the market-oriented discourse right to continued innovation-based voice technology to key components of voice-based technology and equipment to control the main raw material resource base of voice-based, brand-based marketing to the right to speak, to build a modern logistics voice-based supply and demand, industry body to create a pricing mechanism based industry voice. For products, from hardware to a large metal, traditional metal to modern hardware changes; for enterprises, and from family business to a modern enterprise transformation; for Yongkang economy, from the wave of  vw touareg car dvd to the headquarters of the economy, the quality of the economy, the brand of economic change. (This article Source: Zhejiang Online News)

2015 lumens of lighting cost per thousand is expected to drop U.S. $ 2-3

market research institute LEDinside organized by the Taiwan Industrial Technology Research Institute co-electro-optic two-day annual seminar LEDforum2010 LED industry development  LED Display Screen LED components and automotive LED to be explored. LEDinside pointed out that 1000 lumens per LED lighting prices and costs about 7-10 U.S. dollars, as costs continued to decline, from 2011 to 2012 onwards, LED lighting market will accelerate carried out, estimates that by 2015, per thousand lumens lighting  renault megane car gps dvd are expected to drop U.S. $ 2-3, then the world will be gradually changed into energy-saving light source, and save more than 30% of energy consumption.
in recent years in all aspects of the application of LED showed a trend of rapid growth, among which the LED lighting, LED backlight applications such as the two most attention. Although LED backlight manufacturers are the main source of revenue profit, but the backlight lighting market is much larger than the size of the market, LED industry chain full lace wig are gearing up now LED lighting-related products into the development and promotion.
Philips (PhilipsLumileds) said that the current LED lighting available for every $ 1 of about 100-150 lumens, the U.S. Department of Energy DOE to achieve the requirements of every $ 1 the goal of 1,000 lumens available, you need a lot of efforts. Color temperature of LUXEONRebel3000K to PhilipsLumileds LED lighting products, for example, the current drive at 350mA, Tj 85 ° C, after improvement, the value of research data company can reach 220 lm / W of efficiency.
LED epitaxy and grain from the perspective of Epistar (2448) General Manager Zhou Ming Chun said chip package prices are subject to 500 lumens / $ 1, to achieve the U.S. Department of Energy (DOE) the target. Crystal electric current has been developed 160lm / w LED chip high voltage drive (HVLED), this will contribute to the development of LED general lighting applications solutions. Luminous efficiency not only due to  shoulder bag driven by the current decreases, so for better heat dissipation problems to solve, with no converters, AC drives can be used. In addition, the new hybrid electric crystal white LED, the laboratory data has reached 168lm / w of the high efficiency and high color rendering technology.
As for how to reduce the cost of LED production, Ulvac ULVAC Japanese Institute of Semiconductor Electronics Dr.KoukouSuu that the Japanese market, the rapid expansion of demand for LED lighting, LED lighting to attract many businesses to invest, but the company's most pressing or to reduce costs and improve product brightness, luminous efficiency. To process, it can be improved part of the process, including PSS, ITO deposition equipment, plasma etching (plasmaetching), and so on.
Veeco Instruments (Veeco) MOCVD Marketing Director Li Jia also stressed that, MOCVD production and productivity is the development of LED industry, one of the most critical aspect, and MOCVD technology advances reduce the manufacturing cost of LED . Including wavelength, brightness, forward voltage, etc. to reduce yield loss, respectively, and the LED wafer costs through sensitivity analysis, emphasis on product uniformity and repeatability, ensuring LED epitaxial production and so on.
other application markets, the lighting giant Osram Osram president and chief executive Dr.AlfredFelder mentioned,  LED ceiling light LED market, due to the emergence of new types of LED light source, so that the depot can cooperate with the LED light source manufacturers more with creative output, and a variety of lights. Meanwhile, the estimated mini-LED light source projector (PicoProjector), to the 2013 market size will grow to 700 million units.
LED street lights, traffic lights and LED market is also an important application areas. EOI Huang Fang-yu, chairman and general manager, said the Chinese market, for example, has been installed in 2009 by 25 million LED lights, Guangdong Province, in 2010 a large-scale demonstration projects to implement the LED industry, is expected to install the LED lights will reach 45 ten thousand. The U.S. also has more than 200 cities in the test equipment of LED lights, and more than 100 cities will notice a large number of purchase LED lights.

GT Solar photovoltaic equipment giant to enter the LED industry

OFweek semiconductor lighting Reuters, reported that the solar photovoltaic equipment maker announced its vw touareg car dvd into an increasingly popular GTSolar LED industry, the natural "body" of the crystal growth equipment has become the best entry point. Acquired in July GTSolar Sapphire U.S. manufacturers CrystalSystems, now in great tape hair and yield enhancing technology, equipment, professional transformation also began marketing the hope that the formal launch in 2012 the growth of sapphire equipment to win market acceptance and recognition.
CrystalSystems company has a unique innovation ASF sapphire growth technology, and different from the usual single crystal pulling method, the exclusive use of the principle of heat exchange equipment and sapphire growth technology can facilitate the growth of large size sapphire crystal ingot, has successfully produced substrate of 6 inches, to reduce the future cost of production of the most powerful LED competitor.
LED backlight from the phone natural human hair is welcome, television and general lighting, display backlighting to replace the 3rd wave of the coming of industry. GTSolar ScottKroeger vice president of marketing, said the early layout of the LED industry and will certainly win the future market. According YoleDeveloppement statistics, sapphire market from 2009 to 2013 will be CAGR27% growth rate, the increase in the market for Asia, the Chinese business opportunities.
still on the market today are usually cable tray with 2-inch sapphire substrate LED, while the major LED's to 4 inches, 6 inches into the pace of development has been taken. GTSolar will own R & D in crystalline silicon furnace equipment manufacturing cost and technology led waterproof Switching Power Supply , and from CrystalSystems's ASF technology fully integrated, sapphire for the growth of the industry to bring professional equipment.

SAFC Hitech factory in Taiwan to expand and strengthen the global high-brightness LED manufacturing capacity

OFweek semiconductor lighting Reuters, recently, SAFC Hitech ® is a Sigma-Aldrich ® Group's  led running text unit, following the March 2010 in the United Kingdom Bromborough manufacturing base to expand production of trimethyl gallium (trimethylgallium, TMG), the announcement by The company plans to establish Filling in Kaohsiung, Taiwan (transfilling), technical services, and the production of LED and silicon semiconductor precursors of new specialized facilities, and further full lace wig in Asia-Pacific electronics market. The new facility is expected to operate at the end of 2011, and the use of existing facilities, development of Kaohsiung's capabilities and expertise, the company's expanding coverage to the Asian market.

this new investment will now shift to the new business facility is expected to expand the company's full bottle service and technical base, and a substantial increase in production of high quality specialized precursor capacity to support emerging high-brightness LED (High Brightness LED, HBLED) market and the silicon semiconductor market, ALD and CVD precursors.

through technology and design development to improve efficiency and reduce energy costs focus is to promote the electronics industry to introduce more "energy conscious" products and systems. As the flat screen TV's backlight and energy-efficient  vw touareg car dvd such use, LED (especially HBLED) explosion in demand, SAFC Hitech continuing to strengthen the HBLED market and reliable supplier of precursor veteran leadership.

SAFC Hitech President Philip Rose, said: "With the rise of mass production we are experiencing in Asia Pacific customers and partnership activities increased significantly, with our response to the rapid expansion of the HBLED market, is committed to promote the expansion of global production of precursors, are closely linked. Kaohsiung expansion of existing facilities is reasonable progress, which will help us support these markets. by local technical service capabilities in the investment and the use of proprietary technologies and capabilities, we can these important natural human hair to increase our bottle filling, manufacturing and services.

SAFC Hitech is currently the city's infrastructure capacity, can handle the laboratory level and characteristics of highly specialized chemical products and has a special Customer Support Center, through the ISO 9001 certification of quality, safety and environmental regulations through ISO 14001 certification. This facility uses proprietary technology to service the semiconductor industry demands high quality precursor This facility integrated inert gas Filling Station (inert atmosphere transfilling station), can detect low metal and oxygen containing  shoulder bag sophisticated analytical instruments, and special cylinder preparation and packaging area. broad structure of government departments (health and safety, quality, accounting, transportation, marketing) to ensure compliance with the highest the standard.

Cummins diesel engine failure analysis of common procedures

troubleshoot operation is a systematic project, so make Cummins diesel engine as a whole (a system), but not as a set of components. Failure to grasp the whole situation, have a comprehensive  led perimeter displays of the operator to observe the engine, and make the necessary checks and to be pointed out that the cause of the failure analysis.
failure to understand the phenomenon
First of all, to listen to and understand the failure to report symptoms. Some signs of failure may be vague, while others may be more specific breakdown.
Although there are many cases of failure can be very quick and simple access to understand, but some people will 2011 sonata dvd of some examples of maintenance, failure analysis is often made on the first conclusion, we can not rule out these problems. The reason why these situations occur, because there was no learned some important information, or to ignore these important cases.
for maintenance personnel, the employer must, in particular to the actual operator asking, so you have a full understanding of failure problems. In some cases only the operator knows, and you must understand these situations. There are other situations, but only by observing the engine is running or after the demolition of some parts can be found.
some of you may recall a similar failure is a special way to exclude. However, the same fault, not always use the same method to deal with.
maintenance personnel can be in the form below to ask questions about data and information needed to diagnose:
1. Diesel usage
failure before any abnormal noise? A load or light load operation? Acceleration or deceleration? Oil pressure or temperature has changed?
whether there was dust or smoke is not normal? climatic conditions? wind much?
road grade at the time how? first aware of how the failure? oil, fuel, coolant consumption much?  buy full lace wig change? How the concentration of smoke?
engine throttle response is sensitive? slowdown normal? stands satisfactory? cold start satisfactory? have been stalled or lack of fire you?
What fuel to use? fuel level and source of what? idling or running at full speed when the surge it? can idle for a long run?
2. Maintenance history
diesel engine is repaired recently? What kind of maintenance?
happened before this failure? Last revised at what time? Recently when oil replacement and the fuel filter?
maintenance system is strict? how to obtain and store the fuel: oil used in the maintenance category and what level?
diesel engine or the number of how many km h? who to repair or adjust?
replace the oil filter when evening bag full-flow oil filter of the filter do? find any metal impurities do?
3. Observations
a clean or dirty diesel? Belt tension situation? Outside without oil, fuel or water leakage? There have been overheating it?
on diesel has made temporary repairs (parts not tighten, broken parts, etc.).
how idle the engine sound? Pulley any chatter put it? Recent repair or replace any parts you?
diesel engine on all or part of the non-standard parts ? whether the adverse pipeline?
oil oil, water and fuel oil level satisfactory it (if it involves the bearing problem, pay attention to the oil situation. have occurred in this case, due to lack of oil to the bearing damage, but only after the operator and then to inject new crankcase oil).
in demolition, and whether the diesel smell, coke, oil sludge, whether under the rocker cover and other adverse conditions?
4. Mechanic before starting maintenance issues to consider
simply ask and understand the situation, not solve any problems. Therefore, you must know before maintenance and fault-related situation, see the interdependence of each issue in order to make judgments.
use all available led waterproof Switching Power Supply with the existing test, the thought process (thinking) is helpful, but not always want to use.
mechanics must be familiar with Chaiyou Fan type, equipment type and operating knowledge. Diesel engine equipment such as torque converters, coolers, and variable speed control and so must be considered.
majority of diesel users to unnecessary downtime and loss caused by premature removal are offensive, so attention should be paid in a planned and targeted maintenance, repair time can make a thorough and a success.
any diesel engine parts because of a problem, may affect the operation of the machine, so you must have extensive experience in identification of diesel engine operation, troubleshooting successfully important condition is to use your knowledge of the diesel engine and parts operation knowledge to troubleshoot the problem, which is a mental logistics activities.
and troubleshooting to find some checks to be carried out, it is not difficult to be done, check the information must be the best backpacks failures. Can not say that the diesel engine out of your eyes with the same last week, a diesel engine failure, that failure on the same reasons.

Classification analysis of the LED power

classification analysis of the LED power supply 1, press the drive can be LED Display Screen into two categories
1.1 constant-current type < p> a, constant current drive circuit output current is constant, and output DC voltage as the load resistance is within a certain range of different sizes change, the load resistance is small, the output voltage is low, the greater the load resistance , the higher the output voltage;
b, constant current circuit is not afraid of the load short-circuit, but the non-load completely open.
c, led constant current driver Mercedes dvd is an ideal drive, but the relatively higher prices.
d, the maximum tolerance should be noted that the use of current and voltage, which limits the number of LED's use;
1.2 regulator type
a, when the steady pressure to determine the parameters of the circuit after the output voltage is fixed, while the output load current is the increase or decrease with changes;
b, open circuit voltage regulator circuit is not afraid of the load, but the non-load full short circuit.
c, the regulator drive circuit drive the LED, each with an appropriate resistor string requires only that the average brightness of each string of LED display;
d, brightness will be affected by rectification from the voltage change.
2, the circuit structure by way of classification
2.1 resistor, capacitor step-down mode
through capacitor step-down, use the flash, due to charge and discharge the role of instantaneous current through the LED a great, easy to damage the chip. Vulnerable to voltage fluctuations, power efficiency is low, and low reliability.
2.2 resistance buck mode
buck through resistance, interference by the larger power grid voltage, regulated power supply is not easy to make, step-down resistor to consume a large proportion of energy, so this is very low power efficiency power supply, and the system's reliability is also low.
2.3 conventional  Cooling tower step-down mode
power, small size, the weight of too much weight, power efficiency is very low, generally only 45% to 60%, so seldom used, reliability is not high.
2.4 electronic transformer step-down mode
lower power efficiency, voltage range is not wide, generally 180 ~ 240V, wave interference.
2.5 RCC buck mode switching power supply
voltage range is wide, the power efficiency is relatively high, generally can be 70% to 80% wider applications. Because of this control mode oscillation frequency is not continuous, switching frequency is not easy to control, load voltage ripple coefficient is relatively large, abnormal loads and poor adaptability.
2.6 PWM control mode switching power supply
mainly consists of four parts, part of the input rectifier, the output rectifier part, PWM voltage control part, switching energy conversion components. PWM switching regulator is the basic working principle of the input voltage, the internal parameters and led waterproof Switching Power Supply load changes, the control circuit is controlled by the difference between signal and reference signal for closed-loop feedback, adjust the main circuit switching device turn-on pulse width, makes the switching power supply output voltage or current stable (ie, the corresponding constant-current power supply or power supply). Power efficiency is extremely high, generally can be 80% to 90%, output voltage and current stability. This circuit has a good general protection handbag online, a high-reliability power supplies.