功率电子技术应用要点课件.ppt

1、1Application Technology of Power Electronics 功功 率率 电电 子子 技技 术术 应应 用用Application Technique of Power Electronics主主 讲：讲：Li Lei职职 称：称：Associate Professor教研室：教研室：Power System and Automation电电 邮：邮：2Application Technology of Power ElectronicsCourse Characteristics:n Professional Coursen Application Techniq

2、uen Dual-Language 3Application Technology of Power ElectronicsText Bookl Jai P.Agrawal.Power Electronic Systems-Theory and Design.Beijing:Tsinghua University Press,2001.4Application Technology of Power ElectronicsReference Booksl 周志敏，周纪海周志敏，周纪海.开关电源实用开关电源实用 技术与应用技术与应用.北京：人民邮电出北京：人民邮电出 版社，版社，2004.l 5

3、考核方式考核方式闭卷考试闭卷考试 70%平时成绩平时成绩 15%Application Technology of Power Electronics实验成绩实验成绩 15%6Application Technology of Power ElectronicsMain Contents:Bird-eye View of Power Electronics Systems Power Electronic Components Power Electronic Converter Circuits Power Electronic Application Systems 7Chapter 1

4、Birds-eye View of Power Electronics SystemsObjectives:l The overall systems view of power electronic converters.l Modeling of elements and systems of power electronic converters.l The desired performance characteristics,which include power efficiency,power factor,etc.Application Technology of Power

5、Electronics8Application Technology of Power Electronics1.1 INTROCDUCTION Electric power is the muscle of modern industry.Electric power must be converted to other energy forms for use.9 Power electronics makes the utilization of electric power smarter.The focus in power electronics is on conversion,

6、efficiency of conversion and control of energy.Development of semiconductor switching devices have contributed very significant for modern power electronics.Application Technology of Power Electronics10u Power Electronics:is the electronics applied to conversion and control of electric power.u Range

7、 of power scale:milliwatts(mW)megawatts(MW)gigawatts(GW)Application Technology of Power Electronics11Application Technology of Power Electronics12Application Technology of Power Electronics13Application Technology of Power Electronics14Application Technology of Power Electronics15Application Technol

8、ogy of Power Electronics16Application Technology of Power Electronics17Application Technology of Power Electronics18Application Technology of Power Electronics19Application Technology of Power Electronics1.2 A Simple Voltage Converter20Application Technology of Power Electronics21Application Technol

9、ogy of Power Electronics22Application Technology of Power Electronics23Application Technology of Power ElectronicsD=switching duty cycleTs=switching periodDC component of vs(t)=average value:01()sTssgsVv t dtDVT24Application Technology of Power Electronics25Application Technology of Power Electronic

10、s26Application Technology of Power Electronics1.3 Systems View of Power Electronic ConvertersConversion of Electric Power27Application Technology of Power ElectronicsTypes of electric power28Application Technology of Power Electronics29Applications of inverter:n Aircraft and space power suppliesn Un

11、interruptible power suppliesn Variable-frequency ac motor drivesn Aircraft variable-speed constant frequency suppliesn Induction heating suppliesApplication Technology of Power Electronics30Application Technology of Power ElectronicsApplications of rectifier:n DC motor drivesn Regulated dc power sup

12、pliesn High voltage dc transmissionn Wind generator converters31Application Technology of Power ElectronicsApplications of DC Chopper:n Electric transportationn High performance regulated power suppliesn Telecommunication power suppliesn DC motor drive systems32Application Technology of Power Electr

13、onicsApplications of AC to AC converter:n Frequency convertern Voltage regulatorsn VAR regulatorsn AC motor speed controlsn Solid-state relays33Application Technology of Power ElectronicsGeneric structure of power electronic system 34Application Technology of Power Electronics351.4 Elements of the C

14、onverter Systems:Modeling and AssumptionsApplication Technology of Power Electronics In general,elements are very complex,nonlinear,time-variant.Elements may be modeled by linear,time-invariant elements if they are used over a smaller time duration,within a limited range of their characteristics.36u

15、 Resistance:V=Ri*R is the only energy dissipating element in power electronic systems.Application Technology of Power Electronics37Application Technology of Power Electronicsu Inductance:LiLdvLdt01(0)tLLLiIv dtL*A large inductor may be modeled by a current source over the segment dt.38Application Te

16、chnology of Power Electronicsu Capacitance:ccdviCdt01(0)tcccvVi dtC*A large capacitor may be modeled by a voltage source over the segment dt.39u Sources:SourceVoltage SourceCurrent SourceSourceDC SourceAC SourceApplication Technology of Power ElectronicsDC Voltage SourceDC Current SourceAC Current S

17、ource AC Voltage Source40 Voltage Source:()()()tss sv tv tZ i t Current Source:()()()stssv ti ti tZApplication Technology of Power Electronics41Application Technology of Power Electronics DC Voltage Source:A source provides a voltage of constant amplitude at all times.*A battery is closest to an ide

18、al dc voltage source.DC Current Source:do not exist in nature.*A preenergized large value inductor can be treated as a dc current source.42Application Technology of Power Electronics AC Voltage Source:A source provides a voltage waveform with periodic variation of amplitude over time.AC Current Sour

19、ce:do not exist in nature.*A practical ac current source can be synthesized from an ac voltage source in series with a large value inductor.43Application Technology of Power Electronicsu Electrical Switch:An ideal electrical switch may be defined as following:In the on state,vsw=0 at all amplitudes

20、and waveforms of the current isw In the off state,isw=0 at all amplitudes and waveforms of the voltage vsw44Application Technology of Power Electronicsisw+vsw_isw+vsw_iswiswiswvswvswvswONOFFONOFFBidirectional Switch Unidirectional Switch 45Application Technology of Power ElectronicsBidirectional swi

21、tch synthesized from unidirectional switchesMulti-way switch synthesized from unidirectional switches46Application Technology of Power Electronicsu Transformer:v111ii2NN2v2A two-winding transformer:1,2,.iidvNidt1212.vvNN47u Loads and sinks Electrical loads can be classified in the following categori

22、es:Resistive:heaters,ovens and furnaces Inductive:motor,electromagnetic relays Capacitive:displays,gas discharge lamps DC current loads:dc motor in constant torque applicationsApplication Technology of Power Electronics48 DC voltage loads:dc motor in constant speed applications,batteries during char

23、ging AC voltage loads:ac voltage BUS,induction and synchronous motors in constant speed applications AC current loads:induction and synchronous motors in constant torque applications Application Technology of Power Electronics49Application Technology of Power Electronics Resistive loads are modeled

24、by pure resistances.The dc current load may be modeled by a dc current sink.The dc voltage load may be modeled by a dc voltage sink.50Application Technology of Power Electronics1.5 Converter Topologyu Inductor in converter topologynot permitted connectionspermitted connectionsLLIooIIIss512211(0)22LL

25、ELiLiApplication Technology of Power Electronics000tTLtv dtIn the steady-state conditions,there is:For a fixed inductance,energy equation is:52Application Technology of Power Electronicsu Capacitor in converter topologynot permitted connectionspermitted connectionsCCVVVVssoo532211(0)22CCECvCvApplica

26、tion Technology of Power ElectronicsIn the steady-state conditions,there is:000tTCti dtFor a fixed capacitance,energy equation is:541.6 Converter Operation and Desired characteristics*Converter operation involves the turning on and off of switches in a periodic sequence.*Converter operation consists

27、 of two phases:the transient phase and the steady-state phase.Application Technology of Power Electronics55Application Technology of Power Electronics Some of the desirable characteristics of the converter operation are:l The output voltage(current)should be set to the desired value and waveform.l T

28、he output voltage(or current)should be insensitive to variations in load,input voltage(or current)and component values.l The converter should cause minimum distortion and loading on the source side.56Application Technology of Power Electronicsl The output voltage or current should have minimum disto

29、rtion and minimum number of undesired components.l A small range of control parameter should be able to control a large variation in output voltage(or current).57Application Technology of Power Electronicsl The converter should exhibit minimum power loss and maximum resistance to transients.l The co

30、nverter elements should store minimum energy,even temporarily.58Application Technology of Power Electronics1.7 Converter Performance Measures*The converter performance consists of the transient and steady state parts.*The transient performance measures are:Transient current from the source Short cir

31、cuit current from the source Surge protection Switch stress59Application Technology of Power ElectronicsSurge protection:n Difference between the maximum transient voltage and the nominal output voltage when the power is turned on and turned off to the converter.n The amount of transient voltage whe

32、n a large load is switched in or out.60Switch stress:n Highest voltage and the highest rate of rise or fall of voltage across the switching device.n Highest current and the highest rate of rise or fall of current through the switching device.Application Technology of Power Electronics61Application T

33、echnology of Power Electronics*The steady-state converter performance measures are:Forward transfer characteristics Reflective characteristics Control characteristics Harmonic profile Component stresses62Application Technology of Power Electronicsu Forward transfer characteristics Voltage transfer r

34、atio:Current transfer ratio:ovvsvTvoiisiTi63 Output variable Input variableac-dc converter:average value rms valuedc-ac converter:rms value dc valuedc-dc converter:average value dc valueac-ac converter:rms value rms of the fundamental harmonic Application Technology of Power Electronics64Application

35、 Technology of Power Electronicsu Reflective characteristics Voltage reflection ratio:Current reflection ratio:svvovRvsvvoiRi65u Control Characteristics It is desirable to have a small variation in the control parameter that would control a large variation in the output variable.Application Technolo

36、gy of Power Electronics66u Harmonic Profile Harmonic profile is the plot of amplitude versus frequency for the ac waveform of voltage,current or instantaneous power.Application Technology of Power Electronics67 Following measures are used for the harmonic profile:Application Technology of Power Elec

37、tronics Average Value Root-mean-square(rms)Value Peak-Peak Ripple Lowest Undesired Harmonic Frequency Total Harmonic Distortion(THD)Power Factor68u Component Stresses The component stress is measured as the ratio of the peak voltage(current)to the rms value on the component.Application Technology of

38、 Power Electronics691.8 Protectionn Surge voltage protectionn Protection against excessive currentn Protection of switching devicesn Over-voltage protectionApplication Technology of Power Electronics70Application Technology of Power Electronicsn Surge voltage protection Selenium diodes and Metal Oxi

39、de Varistors(MOV)are commonly used.n Protection against excessive current Fuse is generally used for protection from short circuit or excessive current conditions.71Application Technology of Power Electronicsn Protection of switching devices Snubbering circuits are used for protection of switching d

40、evices.n Over-voltage protection 721.9 Packaging The roles of the package design are:lRemoving internal heat and control of internal temperature profile of components.lShielding of converter from external and intra-component electromagnetic interference.lReducing parasitic elements such as the self-inductance,stray capacitance and induction,etc.Application Technology of Power Electronics