外文翻譯--- 開關(guān)模式中功率半導(dǎo)體的應(yīng)用

1、外文文獻及譯文Using Power Semiconductors in Switched Mode TopologiesThe electric energy is not normally used in the form in which it was produced or distributed. Practically all electronic systems require some form of energy co

2、nversion. A device that transfers electric energy from a given source to a given load using electronic circuits is referred to as Power Supply.A typical application of a power supply unit (PSU) is convert utility AC volt

3、age into regulated DC voltage required for electronic equipment. Nowadays in PSU the energy flow is controlled with semiconductors that are continuously switching on an off with high frequency. Such devices are referred

4、to as switch mode power supplies or SMPS. They offer greater efficiency compared with linear supplies because a switch can control energy flow with low losses: when a switch is off, it blocks the flow of voltage and curr

5、ent, can be relatively low in both states. SMPS are also smaller in size and lighter in weight due to the reduced size of passive components and lower heat generation. The industry tended toward miniaturization, advancem

6、ents in semiconductor technology, as well as various energy efficiency regulations have made “switch“ the dominant type of PSR across practically the full spectrum of applications. Most of the switchers manufactured toda

7、y for AC input applications include a PFC front end.Power supplies in the mid–70’s. We identified these as SWITCHMODE products. A switching power supply designed using ON Semiconductor components can rightfully be called

8、 a SWITCH MODE power supply or SMPS.In general, SMPS can be classified into four types according to the input and output waveforms:AC in, DC out: rectifier, off-line converter input stage DC in, DC out: voltage converter

9、, or current converter, or DC to DC converter AC in, AC out: frequency changer, cycloconverter, transformer DC in, AC out: inverterFor many years the world of power supply design has seen a gradual movement away from the

10、 use of linear power supplies to the more practical switched mode power supply (S.M.P.S.). The linear power supply contains a mains transformer and a dissipative series regulator. This means the supply has extremely larg

11、e and heavy switching power supplies since we introduced bipolar power transistors and rectifiers designed specifically for switchingEfficient conversion of electrical power is becoming a primary concern to companies and

12、 to society as a whole. Switching power supplies offer not only higher efficiencies but also offer greater flexibility to the designer. Recent advances in semiconductor, magnetic and passive technologies make the switchi

13、ng power supply an ever more popular choice in the power conversion arena today.Historically, the linear regulator was the primary method of creating a regulated output voltage. It operates by reducing a higher input vol

14、tage down to the lower output voltage by linearly controlling the conductivity of a series pass power device in response to changes in its load. This results in a large voltage being placed across the pass unit with the

15、load current flowing through it. This headroom loss causes the linear regulator to only be 30 to 50 percent efficient. That means that for each watt delivered to the load, at least a watt has to be dissipated in heat. Th

16、e cost of the heatsink actually makes the linear regulator uneconomical above 10 watts for small applications. Below that point, however, they are cost effective in step-down applications. The switching regulator operate

17、s the power devices in the full-on and cutoff states. This then results in either large currents being passed through the power devices with a low “on” voltage or no current flowing with high voltage across the device. T

18、his results in a much lower power being dissipated within the supply. The average switching power supply exhibits efficiencies of between 70 to 90 percent, regardless of the input voltage. Higher levels of integration ha

19、ve driven the cost of switching power supplies downward which makes it an attractive choice for output powers greater than 10 watts or where multiple outputs are desired.A topology is the arrangement of the power devices

20、 and their magnetic elements. Each topology has its own merits within certain applications. Some of the factors which determine the suitability of a particular topology to a certain application are:1) Is the topology ele

21、ctrically isolated from the input to the output or not.2) How much of the input voltage is placed across the inductor or transformer.3) What is the peak current flowing through the power semiconductors.4) Are multiple ou

22、tputs required.5) How much voltage appears across the power semiconductors.The first choice that faces the designer is whether to have input to output transformer isolation. Non-isolated switching power supplies are typi