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switch power supply in modern power technology is the application of power electronic semiconductor devices and integrated automatic control, computer (microprocessor) technology and multidisciplinary edge of hand in the technology of electromagnetic technology. in all kinds of high quality, high efficiency, high reliability of power supply plays a key role, is the concrete application of modern power electronic technology.

current, power electronics as energy-saving, section, automation, intelligent, electromechanical integration, the basis of the application technology is moving in high frequency, modular hardware structure and the direction of green product performance. power electronic technology in the near future, will make the power more mature technology, economy, practical, achieve high efficiency and high quality.

1. the development of power electronic technology the development direction of modern power electronic technology, from is given priority to with low frequency technology deal with the problem of the traditional power electronics, to give priority to with high frequency technology to deal with problems of modern power electronics.

power electronic technology began in the early 50 s at the end of the silicon rectifier device, its development has experienced the era, inverter, rectifier and inverter, and promoted the power electronic technology in many new areas of application. developed in the late eighty s and early ninety s, represented by power mosfet and igbt and high frequency, high voltage and large current of power semiconductor compound device, indicates that the traditional power electronic technology has entered the modern era of power electronics.

1.1 era of high power rectifier industrial electricity provided by the (50 hz) power frequency ac generators, but about 20% of electricity consumption in the form of dc, one of the most typical is electrolytic (non-ferrous metal and chemical raw materials need to direct current (dc) solution), traction (electric locomotive, the electric drive of diesel locomotive, urban subway locomotives, trolley buses,) and dc transmission (rolling, paper making, etc.) the three areas. high-power silicon rectifier can efficiently the power frequency alternating current into direct current, so in the 60 s and seventy s, high power silicon rectifier and the development and application of the brake pipe to great development. around when domestic raised - once bulk sample of the silicon rectifier plant, at present the national large and small manufacturing silicon rectifier semiconductor manufacturers is the product of at that time.

1.2 inverter times appeared in the seventy s a worldwide energy crisis, ac motor variable frequency radcliffe speed rapid development with remarkable energy-saving effect. the key technology of variable frequency speed regulation is to direct current (dc) of 0 ~ 100 hz ac inverter. in the seventy s and seventy s, with the popularity of variable frequency speed regulating device, power inverter with power thyristor, giant transistor (gtr) and gate turn off thyristor (gt0) become the protagonist of the power electronic devices. similar applications include high voltage dc output, static type dynamic reactive power compensation, etc. at this time of the power electronic technology has been able to realize rectifier and inverter, the working frequency is low, limited in the low-frequency range.

1.3 inverter era in the eighty s, the mass and the rapid development of very large scale integrated circuit technology, laid the groundwork for the development of modern power electronic technology. will fine processing technology of integrated circuit technology and the technology of high voltage large current organic combination, appear a batch of new type of all control power device, the first is the advent of power m0sfet, led to the medium and small power sources to the development of high frequency, then the insulated gate bipolar transistor (igbt), and opportunity for development of large and medium power sources to the high frequency. thereafter, mosfet and igbt of power electronics is the traditional to the modern transformation of power electronics. according to statistics, by the end of 1995, power m0sfet and gtr in power semiconductor devices on the market has reached the split, and replace gtr with igbt have been established in the field of power electronics. the development of the new device not only provides a high frequency ac motor frequency control of motor speed, so as to further perfect the performance is reliable, and makes the modern electronic technology to the development of high frequency and continuously, for high efficiency saving material and energy saving of electrical equipment, realize the small, lightweight, mechanical and electrical integration and intelligentization provides important technical foundation.

2. the application field of modern power electronics

2.1 computer efficient green power high speed development of computer technology to lead the human into the information society, but also promoted the rapid development of power technology. in the eighty s, computer fully adopt the switching power supply, the first complete computer power generation. then switch power supply technology successively in the electronic and electrical devices.

the development of computer technology, the green computer and green power is put forward. green computer refers to harmless to the environment, personal computers and related products green power refers to the green computer related efficiently save electricity power supply, according to the u.s. environmental protection agency l992 june 17 "energy star" program, desktop pc or related peripheral equipment, the power consumption in the sleep state if less than 30 watts, accord with the requirement of green computer, the basic way to improve the power efficiency is to reduce the power consumption. current efficiency is 75% of the 200 watts of switch power supply, power supply itself should consume 50 watts of energy.

2.2 communication high frequency switch power supply, telecommunication industry has been heavily promoted by the rapid development of the development of communication power supply. high-frequency miniaturization of switch power supply and its technology has become the mainstream of modern communication power supply system. in the field of communication, often will be called a rectifier power supply, and dc - dc (dc/dc) converter referred to as the secondary power supply. is the role of a power single-phase or three-phase ac power grid to transform the nominal value of 48 v dc power supply. in spc exchange with a power supply at present, the traditional phased type regulated power supply has been replaced with high frequency switching power supply, high-frequency switching power supply (also known as switch mode rectifier smr) by mosfet and igbt high frequency work, general control switch frequency in 50-100 khz range, to achieve high efficiency and miniaturization. growing in recent years, the power switch rectifier capacity, capacity of f from 48 v / 12.5 a, 48 v / 20 a expanded to 48 48 v / 400 v / 200 a, a. because there are many types of communications equipment used in the integrated circuit, the power supply voltage is also each are not identical, in communication power supply system with high power density of high frequency dc - dc isolation power supply module, from the middle busbar voltage (generally for 48 v dc) into the various dc voltage, which can greatly reduce the loss, convenient maintenance, and installation, increase is very convenient. generally can be directly on the standard control panel, the demands of the secondary power supply is a high power density. because of the increasing communication capacity of, communication power supply capacity will also continue to increase.

2.3 dc - dc dc/dc converter (dc/dc) converter to a fixed dc voltage transformation as a variable dc voltage, this technology is widely used in the trolley buses, the subway trains, stepless variable speed and the control of electric vehicle, and to make the control to obtain smooth acceleration, quick response performance, and at the same time receive the effect of saving energy. using dc chopper instead of rheostat can save power (20 ~ 30) %. the dc chopper can not only acts as regulating (switching power supply), but also can effectively inhibit the action of the grid side harmonic current noise.

communication power supply of the secondary power supply dc/dc converter has been commercialized, module using high frequency pwm technology, switching frequency is controlled in 500 khz, with the development of large scale integrated circuit, power supply module to realize miniaturization, therefore to improve switch frequency and adopt a new circuit topology, there are some of the company development and production with zero current switch and zero voltage switching technology of secondary power supply module, power density are improved greatly.

2.4 uninterruptible power supply (ups)

uninterruptible power supply (ups) is a computer and communications systems and required to provide necessary occasions cannot interrupt a high reliable, high performance power supply. ac mains input into dc rectifier, part of the energy to the battery charging, by another part of the energy to ac inverter, the switch to the load. for the inverter failure can still provide energy to the load, the other standby power by power switch all the way.

modern ups generally adopts the pulse width modulation technology and power m0sfet, igbt, such as modern power electronic devices, power supply noise is reduced, the efficiency and reliability. the introduction of the microprocessor hardware and software technology, can realize the intelligent management of ups, for remote maintenance and remote diagnosis.

the maximum capacity of on-line ups can do 600 kva. subminiature ups is also very rapid development, already has 0.5 kva, 3 kva lkva, 2 kva, such as a variety of specifications of the products.

2.5 inverter power supply inverter power supply is mainly used in ac motor frequency control of motor speed, which occupy a position has become increasingly important in electric drive system, have obtained enormous energy saving effect. the inverter power supply main circuit adopts ac - dc - ac solution. power through the rectifier power frequency into fixed dc voltage, and then made up of high-power transistors or igbt pwm high frequency converter, dc voltage inverter into ac output voltage and variable frequency, power supply output waveform similar to sine wave, used to drive ac asynchronous motor to realize stepless speed regulation.

under the 400 kva inverter power supply series products in the world has come out. in the early eighty s, japanese toshiba company the first ac variable frequency speed regulation technology was applied to the air conditioner. to 1997, its share has reached more than 70% of the japanese household air conditioning. frequency conversion air conditioning has the advantages of comfortable, energy-saving. beginning in the early 90 s research frequency conversion air conditioning, frequency conversion air conditioner, in 96 the introduction of production line production gradually formed frequency conversion air conditioning development and production of hot spots. until around 2000 is expected to form a climax. in addition to variable frequency power supply, frequency conversion air conditioning also requires suitable for the compressor motor frequency control of motor speed. optimizing control strategy of functional components, is air conditioning inverter power supply developed further development direction.

2.6 high frequency inverter welding rectifier power supply high frequency inverter welding rectifier power supply is a kind of new welding machine power supply of high performance, high efficiency, save material, represents the development direction of the welding machine power supply today. due to the large capacity igbt module, the power supply more has a broad application prospect.

inverter welding power source are mostly adopts ac - dc - ac - dc (ac - dc - ac - dc) transformation method. 50 hz alternating current through the whole bridge rectifier into dc, igbt pwm high frequency transformation of dc inverter into 20 khz high frequency rectangular wave and the high-frequency transformer coupling, become a stable dc after rectifying filtering, arc power supply is used.

due to the working conditions of welding power supply, frequent under alternating short circuit, arc, open change, thus the work reliability of high frequency inverter welding rectifier power supply problem become the key problem, is also the most concern of the user. using microprocessor as a pulse width modulation (pwm) controller, through the parameters and the extraction and analysis of information, to predict various working status, the purpose of system, in turn, make adjustments to the system and processing in advance, solved the high power igbt inverter power supply reliability.

abroad can be done in inverter welding machine has been rated the welding current is 300 a, duty rate is 60%, the load voltage 60 ~ 75 v, current adjusting range is 5 ~ 300 a, 29 kg in weight.

2.7 power switch type high voltage high power dc power supply switch type high voltage dc power supply is widely used in electrostatic precipitation, water quality improvement, medical x-ray and ct machine and other large equipment. voltage up to 50 ~ l59kv, current of 0.5 a above, power up to 100 kw. since the 70 s, japanese companies began to adopt inverter technology, the grid inverter for about 3 khz after rectifying of intermediate frequency, then the booster. into the 80 s, the high frequency switching power supply technology is developing rapidly. germany's siemens company adopts power transistor is done advocate switching element, to increase the frequency of switching power supply to more than 20 khz. and dry type transformer technology has been successfully applied to the high frequency high voltage power supply, cancelled the high voltage transformer oil tank, reduce the volume of transformer system further.