电力电子技术双语课件第3-4章

1、Power ElectronicsChapter 3 AC to DC Converters (Rectifiers)Power ElectronicsChapter 3 Outline3.1 Single-phase controlled rectifier3.2 Three-phase controlled rectifier 3.3 Effect of transformer leakage inductance on rectifier circuits3.4 Capacitor-filtered uncontrolled rectifier3.5 Harmonics and powe

2、r factor of rectifier circuits3.6 High power controlled rectifier3.7 Inverter mode operation of rectifier circuit3.8 Realization of phase-control in rectifier circuitsOutline3.1 Single-phase contro3.1 Single-phase controlled (controllable) rectifier3.1.1 Single-phase half-wave controlled rectifier3.

3、1.2 Single-phase bridge fully-controlled rectifier 3.1.3 Single-phase full-wave controlled rectifier3.1.4 Single-phase bridge half-controlled rectifier3.1 Single-phase controlled 3.1.1 Single-phase half-wave controlled rectifierHalf-wave, single-pulseTriggering delay angle, delay angle, firing angle

4、Resistive load(3-1)3.1.1 Single-phase half-wave 3.1.1 Single-phase half-wave controlled rectifierInductive (resistor-inductor) load3.1.1 Single-phase half-wave Basic thought process of time-domain analysis for power electronic circuitsThe time-domain behavior of a power electronic circuit is actuall

5、y the combination of consecutive transients of the different linear circuits when the power semiconductor devices are in different states.t = a ，id= 0(3-3)(3-2)Basic thought process of time-Single-phase half-wave controlled rectifier with freewheeling diodeMaximum forward voltage, maximum reverse vo

6、ltageDisadvantages:Only single pulse in one line cycleDC component in the transformer currentInductive load (L is large enough) VTia)Tu1u2uVTLRdudVDiRVDR(3-5)(3-6)(3-7)(3-8)Single-phase half-wave control3.1.2 Single-phase bridge fully-controlled rectifierFor thyristor: maximum forward voltage, maxim

7、um reverse voltageAdvantages: 2 pulses in one line cycleNo DC component in the transformer currentResistive loaddRTu1u2i2abVT1VT3VT2VT4udia)3.1.2 Single-phase bridge 3.1.2 Single-phase bridge fully- controlled rectifierResistive loadAverage output (rectified) voltage (3-9)Average output current (3-1

8、0)For thyristor (3-11) (3-12) For transformer (3-13)3.1.2 Single-phase bridge full3.1.2 Single-phase bridge fully-controlled rectifierCommutationThyristor voltages and currentsTransformer current Inductive load(L is large enough)(3-15)3.1.2 Single-phase bridge Electro-motive-force (EMF) loadDisconti

9、nuous current idWith resistorElectro-motive-force (EMF) loaElectro-motive-force (EMF) loadWith resistor and inductorWhen L is large enough, the output voltage and current waveforms are the same as ordinary inductive load.When L is at a critical value(3-17)Electro-motive-force (EMF) loa3.1.3 Single-p

10、hase full-wave controlled rectifierTransformer with center tapComparison with single-phase bridge fully-controlled rectifier3.1.3 Single-phase full-wave 3.1.4 Single-phase bridge half-controlled rectifierHalf-controlComparison with fully-controlled rectifierAdditional freewheeling diodeabRLu2i2udidV

11、T1VT2VD3VD4VDRT3.1.4 Single-phase bridge Another single-phase bridge half-controlled rectifierComparison with previous circuit:No need for additional freewheeling diodeIsolation is necessary between the drive circuits of the two thyristorsAnother single-phase bridge hSummary of some important points

12、 in analysisWhen analyzing a thyristor circuit, start from a diode circuit with the same topology. The behavior of the diode circuit is exactly the same as the thyristor circuit when firing angle is 0. A power electronic circuit can be considered as different linear circuits when the power semicondu

13、ctor devices are in different states. The time-domain behavior of the power electronic circuit is actually the combination of consecutive transients of the different linear circuits. Take different principle when dealing with different loadFor resistive load: current waveform of a resistor is the sa

14、me as the voltage waveformFor inductive load with a large inductor: the inductor current can be considered constantSummary of some important poin3.2 Three-phase controlled (controllable) rectifier3.2.1 Three-phase half-wave controlled rectifier (the basic circuit among three-phase rectifiers)3.2.2 T

15、hree-phase bridge fully-controlled rectifier (the most widely used circuit among three-phase rectifiers)3.2 Three-phase controlled 3.2.1 Three-phase half-wave controlled rectifierCommon-cathode connectionNatural commutation pointResistive load, a = 03.2.1 Three-phase half-wave Resistive load, a = 30

16、Resistive load, a = 30Resistive load, a = 60Resistive load, a = 60Resistive load, quantitative analysisWhen a 30, load current id is continuous. When a 30, load current id is discontinuous. (3-18)(3-19)Average load currentThyristor voltages(3-20)1- resistor load 2- inductor load 3- resistor-inductor

17、 loadResistive load, quantitative aInductive load, L is large enoughLoad current id is always continuous. Thyristor voltage and currents, transformer current(3-18)(3-23)(3-24)(3-25)Inductive load, L is large eno3.2.2 Three-phase bridge fully-controlled rectifierCommon-cathode group and common-anode

18、group of thyristorsNumbering of the 6 thyristors indicates the trigger sequence. Circuit diagramddbacidudVT1VT3VT5VT4VT6VT221Tniaload3.2.2 Three-phase bridge Resistive load, a = 0Resistive load, a = 0Resistive load, a = 30Resistive load, a = 30Resistive load, a = 60Resistive load, a = 60Resistive lo

19、ad, a = 90Resistive load, a = 90Inductive load, a = 0Inductive load, a = 0Inductive load, a = 30Inductive load, a = 30Inductive load, a = 90Inductive load, a = 90PowerElectronics31Quantitative analysisAverage output voltage For resistive load, When a 60, load current id is discontinuous.Average outp

20、ut current (load current)Transformer currentThyristor voltage and currentSame as three-phase half-wave rectifierEMF load, L is large enoughAll the same as inductive load except the calculation of average output current(3-26)(3-20)(3-27)(3-28)(3-29)PowerElectronics31Quantitative3.3 Effect of transfor

21、mer leakage inductance on rectifier circuits In practical, the transformer leakage inductance has to be taken into account. Commutation between thyristors thus can not happen instantly, but with a commutation process. 3.3 Effect of transformer leakCommutation process analysisCirculating current ik d

22、uring commutationCommutation angle Output voltage during commutationub-ua = 2LBdia/dtik: 0 Idia = Id-ik : Id 0ib = ik : 0 Id(3-30)Commutation process analysisCiReduction of average output voltage due to the commutation processCalculation of commutation angleId ,gXB ,gFor a 90o , a , gQuantitative ca

23、lculation(3-31)(3-36)Reduction of average output voSummary of the effect on rectifier circuitsConclusionsCommutation process actually provides additional working states of the circuit. di/dt of the thyristor current is reduced.The average output voltage is reduced. Positive du/dtNotching in the AC s

24、ide voltage Single-phase full waveSingle-phase bridgeThree-phase half-waveThree-phase bridgem-pulse recfifier CircuitsSummary of the effect on recti3.4 Capacitor-filtered uncontrolled (uncontrollable) rectifierEmphasis of previous sectionsControlled rectifier, inductive loadUncontrolled rectifier: d

25、iodes instead of thyristorsWide applications of capacitor-filtered uncontrolled rectifierAC-DC-AC frequency converterUninterruptible power supplySwitching power supply3.4.1 Capacitor-filtered single-phase uncontrolled rectifier3.4.2 Capacitor-filtered three-phase uncontrolled rectifier3.4 Capacitor-

26、filtered uncont3.4.1 Capacitor-filtered single-phase uncontrolled rectifierSingle-phase bridge, RC load3.4.1 Capacitor-filtered singl3.4.1 Capacitor-filtered single-phase uncontrolled rectifierSingle-phase bridge, RLC load3.4.1 Capacitor-filtered singl3.4.2 Capacitor-filtered three-phase uncontrolle

27、d rectifierThree-phase bridge, RC load3.4.2 Capacitor-filtered three3.4.2 Capacitor-filtered three-phase uncontrolled rectifierThree-phase bridge, RC loadWaveform when wRC1.732a）wRC= b）wRC 0Waveforms when a 0Comparison with 3-phase half-waverectifier and 3-phase bridge rectifierVoltage output capabi

28、litySame as 3-phase half-wave rectifierHalf of 3-phase bridge rectifierCurrent output capabilityTwice of 3-phase half-wave rectifierTwice of 3-phase bridge rectifierApplicationsLow voltage and high current situationsComparison with 3-phase half-w3.6.2 Connection of multiple rectifiersElectronicsPowe

29、rLarger output current: parallel connectionConnection of multiple rectifiersTo increase the output capacityTo improve the AC side current waveform and DC side voltage waveformLarger output voltage: series connection3.6.2 Connection of multiple rPhase-shift connection of multiple rectifiersParallel c

30、onnection12-pulse rectifier realized by paralleled 3-phase bridge rectifiersPhase-shift connection of multPhase-shift connection of multiple rectifiers12-pulse rectifier realized by series 3-phase bridge rectifiersSeries connectionPhase-shift connection of multVoltageAverage output voltage Parallel

31、connection: Series connection:Output voltage harmonics Only 12m harmonics existInput (AC side) current harmonicsOnly 12k1 harmonics existConnection of more 3-phase bridge rectifiersThree: 18-pulse rectifier (20 phase difference)Four: 24-pulse rectifier (15 phase difference)Quantitative analysis of 1

32、2-pulse rectifierVoltageQuantitative analysis oSequential control of multiple series-connected rectifiersCircuit and waveforms of series-connectedthree single-phase bridge rectifiersSequential control of multiple3.7 Inverter mode operation of rectifiersReview of DC generator-motor systemshould be av

33、oided3.7 Inverter mode operation ofInverter mode operation of rectifiers Rectifier and inverter mode operation of single-phasefull-wave converterInverter mode operation of recNecessary conditions for the inverter mode operation of controlled rectifiersThere must be DC EMF in the load and the directi

34、on of the DC EMF must be enabling current flow in thyristors. (In other word EM must be negative if taking the ordinary output voltage direction as positive.) a 90 so that the output voltage Ud is also negative. Necessary conditions for the iInverter mode operation of 3-phase bridge rectifierInversi

35、on angle (extinction angle) a + =180 Inverter mode operation of 3-Inversion failure and minimum inversion anglePossible reasons of inversion failuresMalfunction of triggering circuitFailure in thyristorsSudden dropout of AC source voltageInsufficient margin for commutation of thyristorsMinimum inver

36、sion angle (extinction angle) bmin=d +g+q （3-109）Inversion failure and minimum 3.8 Realization of phase-control in rectifier circuitsObjectHow to timely generate triggering pulses with adjustable phase delay angleConstitutionSynchronous circuitSaw-tooth ramp generating and phase shiftingPulse genera

37、tingIntegrated gate triggering control circuits are very widely used in practice.3.8 Realization of phase-contrA typical gate triggering control circuitA typical gate triggering contWaveforms of the typical gate triggering control circuitPowerElectronics78Waveforms of the typical gateHow to get sync

38、hronous voltage for the gate triggering control circuit of each thyristorFor the typical circuit on page 20, the synchronous voltage of the gate triggering control circuit for each thyristor should be lagging 180 to the corresponding phase voltage of that thyristor.D,y 11D,y 5-11TRTSuAuBuCuaubuc- us

39、a- usb- usc usa usb uscUcUsc-UsaUbUsb-Usc-UsbUaUsaUABHow to get synchronous voltagePower ElectronicsChapter 4 DC to AC Converters( Inverters )Power ElectronicsChapter 4 Applications of InvertersConversion of electric power from DC type energy sources to AC type loadBatteryPhotovoltaic cell (Solar ce

40、ll)Fuel cellAs a part of composite converterAC-DC-AC frequency converter (for AC motor drive)AC-DC-AC constant-voltage constant-frequency converter (for uninterruptable power supplies)AC-DC-AC Converters for induction heatingAC-DC-AC-DC switching power suppliesApplications of InvertersConveOutline4.

41、1 Commutation4.2 Voltage source inverters4.3 Current source inverters4.4 Multiple-inverter connections and multi-level inverters Outline4.1 Commutation4.1 Commutation typesA classification of invertersSquare-wave inverters (are discussed in this chapter)PWM inverters ( will be discussed in Chapter 6

42、)The concept of commutationBasic operation principle of invertersLoadS1S2S3S4iouoUd4.1 Commutation typesA classif4 types of commutation Device commutation: Fully-controlled devices: GTO, IGBT, MOSFET Line commutation Phase-controlled rectifier Phase-controlled AC controller Thyristor cycloconverter

43、Load commutation Forced commutation4 types of commutation Device Load commutation Condition: Load current is leading load voltage Application: capacitive load, synchronous motorLoad commutation Condition: Lo Forced commutation (capacitance commutation)Direct-CoupledWith Coupling-Inductor Forced comm

44、utation (capacitAnother classification of commutationsSelf-commutationDevice commutationForced commutationLine commutationLoad commutation4 types of CommutationsExternal commutationFor fully-controlled devicesFor thyristorsAnother classification of comm2 classes of invertersVoltage Source Inverter (

45、VSI)Current Source Inverter (CSI)2 classes of invertersVoltage 4.2 Voltage source inverter (VSI) DC side is constant voltage, low impedance (voltage source, or bulk cap) AC side voltage is square wave or quasi-square wave. AC side current is determined by the load. Anti-parallel diodes are necessary

46、 to provide energy feedback path. (freewheeling diodes , feedback diodes)+-CRLUdV1V2V3V4VD1VD2VD3VD4uoioFeatures4.2 Voltage source inverter (VSingle-phase half bridge VSI The current conducting path is determined by the polarity of load voltage and load current. (This is true for analysis of many po

47、wer electronics circuits.)-RLUdiouoV1V2VD1VD2Ud2Ud2The magnitude of output square-wave voltage is Ud/2.uoUmiot1t2t3t4t5t6V1V2V1V2VD1VD2VD1VD2UG1UG2Single-phase half bridge VSI Single-phase full bridge VSIOperation principle+-CRLUdV1V2V3V4VD1VD2VD3VD4uoio The magnitude of output square-wave voltage i

48、s Ud. The effective value of output voltage (or fundamental output voltage) can be changed by changing Ud.uoUmiot1t2t3t4t5t6V1V2V1V2VD1VD2VD1VD2UG1,4UG2,3VD4VD3VD4VD34343VVVV Single-phase full bridge VSIOFourier series extension of output voltageMagnitude of output voltage fundamental component Effe

49、ctive value of output voltage fundamental component Single-phase full bridge VSIQuantitative analysis(4-1)(4-2)(4-3)Fourier series extension of ou Single-phase full bridge VSI Output voltage control by phase-shift+-CRLUdV1V2V3V4VD1VD2VD3VD4uoio Single-phase full bridge VSI Inverter with center-tappe

50、d transformerpush-pull inverterInverter with center-tapped tr Three-phase VSI 180o conduction Dead time (blanking time) to avoid “shoot through” Three-phase VSI 180o conducti Three-phase VSIBasic equations to obtain voltage waveformsFor line voltageFor phase voltage of the load Three-phase VSIBasic

51、equationThree-phase VSIFourier series extension of output line-to-line voltageMagnitude of output voltage (line-to-line) fundamental component Effective value of output voltage (line-to-line) fundamental componentQuantitative analysis(4-8)(4-10)(4-11)Three-phase VSIFourier series 4.3 Current source inverter (CSI) DC side is constant current, high impedance (current source, or large inductor) AC side current is quas