,Power,Electronics,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,109,Power,Electronics,Chapter 3,AC to DC Converters,(Rectifiers),Power ElectronicsChapter 3,Outline,3.1 Single-phase controlled rectifier,3.2 Three-phase controlled rectifier,3.3 Effect of transformer leakage inductance on rectifier circuits,3.4 Capacitor-filtered uncontrolled rectifier,3.5 Harmonics and power factor of rectifier circuits,3.6 High power controlled rectifier,3.7 Inverter mode operation of rectifier circuit,3.8 Realization of phase-control in rectifier circuits,Outline3.1 Single-phase contro,3.1 Single-phase controlled (controllable) rectifier,3.1.1 Single-phase half-wave controlled rectifier,3.1.2 Single-phase bridge fully-controlled rectifier,3.1.3 Single-phase full-wave controlled rectifier,3.1.4 Single-phase bridge half-controlled rectifier,3.1 Single-phase controlled,3.1.1 Single-phase half-wave controlled rectifier,Half-wave, single-pulse,Triggering delay angle, delay angle, firing angle,Resistive load,(3-1),3.1.1 Single-phase half-wave,3.1.1 Single-phase half-wave controlled rectifier,Inductive (resistor-inductor) load,3.1.1 Single-phase half-wave,Basic thought process of time-domain analysis for power electronic circuits,The time-domain behavior of a power electronic circuit is actually the combination of consecutive transients of the different linear circuits when the power semiconductor devices are in different states.,t,=,a,，,i,d,= 0,(3-3),(3-2),Basic thought process of time-,Single-phase half-wave controlled rectifier with freewheeling diode,Maximum forward voltage, maximum reverse voltage,Disadvantages:,Only single pulse in one line cycle,DC component in the transformer current,Inductive load (L is large enough),VT,i,a),T,u,1,u,2,u,VT,L,R,d,u,d,VD,i,R,VD,R,(3-5),(3-6),(3-7),(3-8),Single-phase half-wave control,3.1.2 Single-phase bridge fully-controlled rectifier,For thyristor: maximum forward voltage, maximum reverse voltage,Advantages:,2 pulses in one line cycle,No DC component in the transformer current,Resistive load,d,R,T,u,1,u,2,i,2,a,b,VT,1,VT,3,VT,2,VT,4,u,d,i,a),3.1.2 Single-phase bridge,3.1.2 Single-phase bridge fully- controlled rectifier,Resistive load,Average output (rectified) voltage (3-9),Average output current,(3-10),For thyristor,(3-11),(3-12),For transformer,(3-13),3.1.2 Single-phase bridge full,3.1.2 Single-phase bridge fully-controlled rectifier,Commutation,Thyristor voltages and currents,Transformer current,Inductive load(L is large enough),(3-15),3.1.2 Single-phase bridge,Electro-motive-force (EMF) load,Discontinuous current i,d,With resistor,Electro-motive-force (EMF) loa,Electro-motive-force (EMF) load,With resistor and inductor,When 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) loa,3.1.3 Single-phase full-wave controlled rectifier,Transformer with center tap,Comparison with single-phase bridge fully-controlled rectifier,3.1.3 Single-phase full-wave,3.1.4 Single-phase bridge half-controlled rectifier,Half-control,Comparison with fully-controlled rectifier,Additional freewheeling diode,a,b,R,L,u,2,i,2,u,d,i,d,VT,1,VT,2,VD,3,VD,4,VD,R,T,3.1.4 Single-phase bridge,Another single-phase bridge half-controlled rectifier,Comparison with previous circuit:,No need for additional freewheeling diode,Isolation is necessary between the drive circuits of the two thyristors,Another single-phase bridge h,Summary of some important points in analysis,When 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 semiconductor 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 load,For resistive load: current waveform of a resistor is the same as the voltage waveform,For inductive load with a large inductor: the inductor current can be considered constant,Summary of some important poin,3.2 Three-phase controlled (controllable) rectifier,3.2.1 Three-phase half-wave controlled rectifier,(the basic circuit among three-phase rectifiers),3.2.2 Three-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 rectifier,Common-cathode connection,Natural commutation point,Resistive load,a,= 0,3.2.1 Three-phase half-wave,Resistive load,a,= 30,Resistive load, a = 30,Resistive load,a,= 60,Resistive load, a = 60,Resistive load, quantitative analysis,When,a,30, load current,i,d,is continuous.,When,a,30, load current,i,d,is discontinuous.,(3-18),(3-19),Average load current,Thyristor voltages,(3-20),1- resistor load 2- inductor load,3- resistor-inductor load,Resistive load, quantitative a,Inductive load, L is large enough,Load current,i,d,is always continuous.,Thyristor voltage and currents, transformer current,(3-18),(3-23),(3-24),(3-25),Inductive load, L is large eno,3.2.2 Three-phase bridge fully-controlled rectifier,Common-cathode group and common-anode group of thyristors,Numbering of the 6 thyristors indicates the trigger sequence.,Circuit diagram,d,d,b,a,c,i,d,u,d,VT,1,VT,3,VT,5,VT,4,VT,6,VT,2,2,1,T,n,i,a,load,3.2.2 Three-phase bridge,Resistive load,a,= 0,Resistive load, a = 0,Resistive load,a,= 30,Resistive load, a = 30,Resistive load,a,= 60,Resistive load, a = 60,Resistive load,a,= 90,Resistive load, a = 90,Inductive load,a,= 0,Inductive load, a = 0,Inductive load,a,= 30,Inductive load, a = 30,Inductive load,a,= 90,Inductive load, a = 90,Power,Electronics,31,Quantitative analysis,Average output voltage,For resistive load, When,a,60, load current,i,d,is discontinuous.,Average output current (load current),Transformer current,Thyristor voltage and current,Same as three-phase half-wave rectifier,EMF load, L is large enough,All the same as inductive load except the calculation of average output current,(3-26),(3-20),(3-27),(3-28),(3-29),PowerElectronics31Quantitative,3.3 Effect of transformer 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 leak,Commutation process analysis,Circulating current,i,k,during commutation,Commutation angle,Output voltage during commutation,u,b,-u,a,= 2L,B,di,a,/dt,i,k,: 0 I,d,i,a,= I,d,-i,k,: I,d,0,i,b,= i,k,: 0 I,d,(3-30),Commutation process analysisCi,Reduction of average output voltage due to the commutation process,Calculation of commutation angle,I,d,g,X,B,g,For,a,90,o,a,g,Quantitative calculation,(3-31),(3-36),Reduction of average output vo,Summary of the effect on rectifier circuits,Conclusions,Commutation 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/dt,Notching in the AC side voltage,Single-phase full wave,Single-phase bridge,Three-phase half-wave,Three-phase bridge,m-pulse recfifier,Circuits,Summary of the effect on recti,3.4 Capacitor-filtered uncontrolled (uncontrollable) rectifier,Emphasis of previous sections,Controlled rectifier, inductive load,Uncontrolled rectifier: diodes instead of thyristors,Wide applications of capacitor-filtered uncontrolled rectifier,AC-DC-AC frequency converter,Uninterruptible power supply,Switching power supply,3.4.1 Capacitor-filtered single-phase uncontrolled rectifier,3.4.2 Capacitor-filtered three-phase uncontrolled rectifier,3.4 Capacitor-filtered uncont,3.4.1 Capacitor-filtered single-phase uncontrolled rectifier,Single-phase bridge,RC,load,3.4.1 Capacitor-filtered singl,3.4.1 Capacitor-filtered single-phase uncontrolled rectifier,Single-phase bridge,RLC,load,3.4.1 Capacitor-filtered singl,3.4.2 Capacitor-filtered three-phase uncontrolled rectifier,Three-phase bridge,RC,load,3.4.2 Capacitor-filtered three,3.4.2 Capacitor-filtered three-phase uncontrolled rectifier,Three-phase bridge,RC,load,Waveform when,w,RC,1.732,a,）,w,RC,=,b,）,w,RC, 0,Waveforms when a 0,Comparison with 3-phase half-waverectifier and 3-phase bridge rectifier,Voltage output capability,Same as 3-phase half-wave rectifier,Half of 3-phase bridge rectifier,Current output capability,Twice of 3-phase half-wave rectifier,Twice of 3-phase bridge rectifier,Applications,Low voltage and high current situations,Comparison with 3-phase half-w,3.6.2 Connection of multiple rectifiers,Electronics,Power,Larger output current: parallel connection,Connection of multiple rectifiers,To increase the output capacity,To improve the AC side current waveform and DC side voltage waveform,Larger output voltage: series connection,3.6.2 Connection of multiple r,Phase-shift connection of multiple rectifiers,Parallel connection,12-pulse rectifier realized by,paralleled 3-phase bridge rectifiers,Phase-shift connection of mult,Phase-shift connection of multiple rectifiers,12-pulse rectifier realized by,series 3-phase bridge rectifiers,Series connection,Phase-shift connection of mult,Voltage,Average output voltage,Parallel connection:,Series connection:,Output voltage harmonics,Only 12,m,harmonics exist,Input (AC side) current harmonics,Only 12k1 harmonics exist,Connection of more 3-phase bridge rectifiers,Three: 18-pulse rectifier (20 phase difference),Four: 24-pulse rectifier (15 phase difference),Quantitative analysis of 12-pulse rectifier,VoltageQuantitative analysis o,Sequential control of multiple series-connected rectifiers,Circuit and waveforms of series-connected,three single-phase bridge rectifiers,Sequential control of multiple,3.7 Inverter mode operation of rectifiers,Review of DC generator-motor system,should be avoided,3.7 Inverter mode operation of,Inverter mode operation of rectifiers,Rectifier and inverter mode operation of single-phasefull-wave converter,Inverter mode operation of rec,Necessary conditions for the inverter mode operation of controlled rectifiers,There must be DC EMF in the load and the direction of the DC EMF must be enabling current flow in thyristors. (In other word,E,M,must be negative if taking the ordinary output voltage direction as positive.),a,90 so that the output voltage,U,d,is also negative.,Necessary conditions for the i,Inverter mode operation of 3-phase bridge rectifier,Inversion angle (extinction angle),a,+,=180,Inverter mode operation of 3-,Inversion failure and minimum inversion angle,Possible reasons of inversion failures,Malfunction of triggering circuit,Failure in thyristors,Sudden dropout of AC source voltage,Insufficient margin for commutation of thyristors,Minimum inversion angle (extinction angle),b,min,=,d,+,g,+,q,（,3-109,）,Inversion failure and minimum,3.8 Realization of phase-control in rectifier circuits,Object,How to timely generate triggering pulses with adjustable phase delay angle,Constitution,Synchronous circuit,Saw-tooth ramp generating and phase shifting,Pulse generating,Integrated gate triggering control circuits are very widely used in practice.,3.8 Realization of phase-contr,A typical gate triggering control circuit,A typical gate triggering cont,Waveforms of the typical gate triggering control circuit,Power,Electronics,78,Waveforms of the typical gate,How to get synchronous voltage for the gate triggering control circuit of each thyristor,For 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,11,D,y,5-11,TR,TS,u,A,u,B,u,C,u,a,u,b,u,c,-,u,sa,-,u,sb,-,u,sc,u,sa,u,sb,u,sc,U,c,U,sc,-,U,sa,U,b,U,sb,-,U,sc,-,U,sb,U,a,U,sa,U,AB,How to get synchronous voltage,Power,Electronics,Chapter 4,DC to AC Converters( Inverters ),Power ElectronicsChapter 4,Applications of Inverters,Conversion of electric power from DC type energy sources to AC type load,Battery,Photovoltaic cell (Solar cell),Fuel cell,As a part of composite converter,AC-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 heating,AC-DC-AC-DC switching power supplies,Applications of InvertersConve,Outline,4.1 Commutation,4.2 Voltage source inverters,4.3 Current source inverters,4.4 Multiple-inverter connections and multi-level inverters,Outline4.1 Commutation,4.1 Commutation types,A classification of inverters,S