功率电子技术应用.ppt

1、1,Application Technology of Power Electronics,功 率 电 子 技 术 应 用 Application Technique of Power Electronics,主 讲：Li Lei 职 称：Associate Professor 教研室：Power System and Automation 电 邮：,2,Application Technology of Power Electronics,Course Characteristics: Professional Course Application Technique Dual-Langua

2、ge,3,Application Technology of Power Electronics,Text Book Jai P.Agrawal. Power Electronic Systems-Theory and Design. Beijing:Tsinghua University Press, 2001.,4,Application Technology of Power Electronics,Reference Books 周志敏，周纪海. 开关电源实用 技术与应用. 北京：人民邮电出 版社，2004. ,5,考核方式,闭卷考试 70%,平时成绩 15%,Application

3、Technology of Power Electronics,实验成绩 15%,6,Application Technology of Power Electronics,Main Contents: Bird-eye View of Power Electronics Systems Power Electronic Components Power Electronic Converter Circuits Power Electronic Application Systems,7,Chapter 1 Birds-eye View of Power Electronics System

4、s Objectives: The overall systems view of power electronic converters. Modeling of elements and systems of power electronic converters. The desired performance characteristics, which include power efficiency, power factor, etc.,Application Technology of Power Electronics,8,Application Technology of

5、Power Electronics,1.1 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, efficiency of conversion and cont

6、rol of energy. Development of semiconductor switching devices have contributed very significant for modern power electronics.,Application Technology of Power Electronics,10,Power Electronics: is the electronics applied to conversion and control of electric power.,Range of power scale:,milliwatts(mW)

7、 megawatts(MW) gigawatts(GW),Application Technology of Power Electronics,11,Application Technology of Power Electronics,12,Application Technology of Power Electronics,13,Application Technology of Power Electronics,14,Application Technology of Power Electronics,15,Application Technology of Power Elec

8、tronics,16,Application Technology of Power Electronics,17,Application Technology of Power Electronics,18,Application Technology of Power Electronics,19,Application Technology of Power Electronics,1.2 A Simple Voltage Converter,20,Application Technology of Power Electronics,21,Application Technology

9、of Power Electronics,22,Application Technology of Power Electronics,23,Application Technology of Power Electronics,D=switching duty cycle Ts=switching period,DC component of vs(t)= average value:,24,Application Technology of Power Electronics,25,Application Technology of Power Electronics,26,Applica

10、tion Technology of Power Electronics,1.3 Systems View of Power Electronic Converters,Conversion of Electric Power,27,Application Technology of Power Electronics,Types of electric power,28,Application Technology of Power Electronics,29,Applications of inverter: Aircraft and space power supplies Unint

11、erruptible power supplies Variable-frequency ac motor drives Aircraft variable-speed constant frequency supplies Induction heating supplies,Application Technology of Power Electronics,30,Application Technology of Power Electronics,Applications of rectifier: DC motor drives Regulated dc power supplie

12、s High voltage dc transmission Wind generator converters,31,Application Technology of Power Electronics,Applications of DC Chopper: Electric transportation High performance regulated power supplies Telecommunication power supplies DC motor drive systems,32,Application Technology of Power Electronics

13、,Applications of AC to AC converter: Frequency converter Voltage regulators VAR regulators AC motor speed controls Solid-state relays,33,Application Technology of Power Electronics,Generic structure of power electronic system,34,Application Technology of Power Electronics,35,1.4 Elements of the Conv

14、erter Systems: Modeling and Assumptions,Application 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 characteristi

15、cs.,36,Resistance: V=Ri * R is the only energy dissipating element in power electronic systems.,Application Technology of Power Electronics,37,Application Technology of Power Electronics,Inductance:,* A large inductor may be modeled by a current source over the segment dt.,38,Application Technology

16、of Power Electronics,Capacitance:,* A large capacitor may be modeled by a voltage source over the segment dt.,39,Sources:,Source,Voltage Source,Current Source,Source,DC Source,AC Source,Application Technology of Power Electronics,DC Voltage Source,DC Current Source,AC Current Source,AC Voltage Sourc

17、e,40,Voltage Source:,Current Source:,Application Technology of Power Electronics,41,Application Technology of Power Electronics,DC Voltage Source: A source provides a voltage of constant amplitude at all times. *A battery is closest to an ideal dc voltage source. DC Current Source: do not exist in n

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

19、 source can be synthesized from an ac voltage source in series with a large value inductor.,43,Application Technology of Power Electronics,Electrical Switch:,An ideal electrical switch may be defined as following: In the on state, vsw=0 at all amplitudes and waveforms of the current isw In the off s

20、tate, isw=0 at all amplitudes and waveforms of the voltage vsw,44,Application Technology of Power Electronics,isw,+ vsw,_,isw,+ vsw,_,isw,isw,isw,vsw,vsw,vsw,ON,OFF,ON,OFF,Bidirectional Switch,Unidirectional Switch,45,Application Technology of Power Electronics,Bidirectional switch synthesized from

21、unidirectional switches,Multi-way switch synthesized from unidirectional switches,46,Application Technology of Power Electronics,Transformer:,v,1,1,1,i,i,2,N,N,2,v,2,A two-winding transformer,47,Loads and sinks,Electrical loads can be classified in the following categories: Resistive: heaters, ovens

22、 and furnaces Inductive: motor, electromagnetic relays Capacitive: displays, gas discharge lamps DC current loads: dc motor in constant torque applications,Application Technology of Power Electronics,48,DC voltage loads: dc motor in constant speed applications, batteries during charging AC voltage l

23、oads: 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 Electronics,49,Application Technology of Power Electronics,Resistive loads are modeled by pure resi

24、stances. The dc current load may be modeled by a dc current sink. The dc voltage load may be modeled by a dc voltage sink.,50,Application Technology of Power Electronics,1.5 Converter Topology,Inductor in converter topology,not permitted connections,permitted connections,L,L,I,o,o,I,I,I,s,s,51,Appli

25、cation Technology of Power Electronics,In the steady-state conditions, there is:,For a fixed inductance, energy equation is:,52,Application Technology of Power Electronics,Capacitor in converter topology,not permitted connections,permitted connections,C,C,V,V,V,V,s,s,o,o,53,Application Technology of

26、 Power Electronics,In the steady-state conditions, there is:,For a fixed capacitance, energy equation is:,54,1.6 Converter Operation and Desired characteristics,* Converter operation involves the turning on and off of switches in a periodic sequence. * Converter operation consists of two phases: the

27、 transient phase and the steady-state phase.,Application Technology of Power Electronics,55,Application Technology of Power Electronics,Some of the desirable characteristics of the converter operation are: The output voltage (current) should be set to the desired value and waveform. The output volta

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

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

30、ments should store minimum energy, even temporarily.,58,Application Technology of Power Electronics,1.7 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 circu

31、it current from the source Surge protection Switch stress,59,Application Technology of Power Electronics,Surge protection: Difference between the maximum transient voltage and the nominal output voltage when the power is turned on and turned off to the converter. The amount of transient voltage when

32、 a large load is switched in or out.,60,Switch stress: Highest voltage and the highest rate of rise or fall of voltage across the switching device. Highest current and the highest rate of rise or fall of current through the switching device.,Application Technology of Power Electronics,61,Application

33、 Technology of Power Electronics,* The steady-state converter performance measures are: Forward transfer characteristics Reflective characteristics Control characteristics Harmonic profile Component stresses,62,Application Technology of Power Electronics,Forward transfer characteristics Voltage tran

34、sfer ratio: Current transfer ratio:,63,Output variable Input variable ac-dc converter: average value rms value dc-ac converter: rms value dc value dc-dc converter: average value dc value ac-ac converter: rms value rms of the fundamental harmonic,Application Technology of Power Electronics,64,Applica

35、tion Technology of Power Electronics,Reflective characteristics Voltage reflection ratio: Current reflection ratio:,65,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 Technology of Pow

36、er Electronics,66,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 Electronics,67,Following measures are used for the harmonic profile:,Application Technology of Power Electronics,Average Value Root-mean-square(rms) Value Peak-Peak Ripple Lowest Undesired Harmoni