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Thyristor

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Thyristor

  1. 1. Objectives…Objectives…Objectives…Objectives…Objectives…Objectives…Objectives…Objectives… PUTPUT (Programmable(Programmable UnijuncionUnijuncion Transistor)Transistor).. SUSSUS (Silicon(Silicon UnilateralUnilateral Switch)Switch).. SCSSCS (Silicon(Silicon ControlledControlled Switch)Switch).. 9/12/2013 Mahesh J. vadhavaniya 1 SCSSCS (Silicon(Silicon ControlledControlled Switch)Switch).. RCTRCT (Reverse(Reverse ConductingConducting Thyristor)Thyristor).. TRIACTRIAC ASCRASCR (Asymmetrical(Asymmetrical Thyristor)Thyristor)..
  2. 2. PUTPUTPUTPUTPUTPUTPUTPUT ProgrammableProgrammableProgrammableProgrammableProgrammableProgrammableProgrammableProgrammable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction TransistorTransistorTransistorTransistorTransistorTransistorTransistorTransistor J1J1 J2J2 J3J3 TransistorTransistorTransistorTransistorTransistorTransistorTransistorTransistor 9/12/2013 Mahesh J. vadhavaniya 2
  3. 3. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) ItIt isis aa fourfour--layerlayer PP--NN--PP--NN solidsolid--statestate devicedevice withwith aa gategate connectedconnected directlydirectly toto thethe sandwichedsandwiched NN--typetype layerlayer.. 9/12/2013 Mahesh J. vadhavaniya 3 J1J1 J2J2 J3J3
  4. 4. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) InIn aa PUT,PUT, GateGate isis alwaysalways biasedbiased positivepositive withwith respectrespect toto CathodeCathode.. WhenWhen anodeanode voltagevoltage exceedsexceeds thethe gategate voltagevoltage byby aboutabout 00..77 v,v, thethe junctionjunction JJ11 getsgets forwardforward biasedbiased andand PUTPUT turnsturns onon.. WhenWhen anodeanode voltagevoltage becomesbecomes lessless thanthan thethe gategate voltage,voltage, PUTPUT isis turnedturned offoff.. 9/12/2013 Mahesh J. vadhavaniya 4 TheThe anodeanode--toto--cathodecathode voltagevoltage VVAKAK thenthen dropsdrops toto aa lowlow level,level, andand thethe devicedevice conductsconducts heavilyheavily untiluntil thethe inputinput voltagevoltage becomebecome tootoo lowlow toto sustainsustain conductionconduction ThisThis actionaction stimulatesstimulates thethe performanceperformance ofof aa UJTUJT.. TheThe anodeanode ofof thethe devicedevice actsacts asas thethe emitteremitter ofof UJTUJT..
  5. 5. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) VV--II CharacteristicCharacteristic ofof PUTPUT 9/12/2013 Mahesh J. vadhavaniya 5
  6. 6. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) TheThe PUTPUT cancan bebe “programmed”“programmed” toto turnturn onon atat aa certaincertain voltagevoltage byby anan externalexternal voltagevoltage dividerdivider.. ThisThis yieldsyields aa curvecurve similarsimilar toto aa UJTUJT.. 9/12/2013 Mahesh J. vadhavaniya 6
  7. 7. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) 9/12/2013 Mahesh J. vadhavaniya 7
  8. 8. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) TheThe termterm “programmable”“programmable” isis appliedapplied becausebecause thethe interinter basebase resistanceresistance RRBBBB,, thethe intrinsicintrinsic standstand--offoff ratioratio ȠȠ andand peakpeak-- pointpoint voltagevoltage VVPP,, asas defineddefined inin UJTUJT cancan bebe programmedprogrammed toto anyany desireddesired valuesvalues throughthrough externalexternal resistorsresistors RRBB11 andand RRBB22 andand thethe supplysupply voltagevoltage VVBBBB.. 9/12/2013 Mahesh J. vadhavaniya 8 FromFrom figurefigure wewe seesee thatthat byby voltagevoltage dividerdivider rulerule whenwhen IIGG==00 GG B1B1 B1B1 B2B2 BBBB BBBBVGG = (RB1B1 / RB1B1 + RB2B2 ) VBBBB = Ƞ VBBBB andand thethe supplysupply voltagevoltage VVBBBB..
  9. 9. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) ItsIts largestlargest ratingrating isis aboutabout 200200 vv andand 11 AA.. PUTPUT isis mainlymainly usedused inin TimeTime--delay,delay, logiclogic andand SCRSCR triggertrigger circuitscircuits.. 9/12/2013 Mahesh J. vadhavaniya 9
  10. 10. PUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (ProgrammablePUT (Programmable UnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunctionUnijunction Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor)Transistor) Load 9/12/2013 Mahesh J. vadhavaniya 10 SCR
  11. 11. SUSSUSSUSSUSSUSSUSSUSSUS Silicon Unilateral SwitchSilicon Unilateral SwitchSilicon Unilateral SwitchSilicon Unilateral SwitchSilicon Unilateral SwitchSilicon Unilateral SwitchSilicon Unilateral SwitchSilicon Unilateral Switch 9/12/2013 Mahesh J. vadhavaniya 11
  12. 12. SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch) AA SUSSUS isis similarsimilar toto aa PUTPUT butbut withwith anan inin--builtbuilt lowlow-- voltagevoltage avalancheavalanche diodediode betweenbetween gategate andand cathodecathode.. 9/12/2013 Mahesh J. vadhavaniya 12
  13. 13. BecauseBecause ofof thethe presencepresence ofof diode,diode, SUSSUS turnsturns onon forfor aa fixedfixed anodeanode--toto--cathodecathode voltagevoltage.. SCR’sSCR’s triggertrigger voltagevoltage and/orand/or currentcurrent varyvary widelywidely withwith changeschanges inin ambientambient temperaturetemperature.. SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch) changeschanges inin ambientambient temperaturetemperature.. 9/12/2013 Mahesh J. vadhavaniya 13 ItsIts largestlargest ratingsratings areare aboutabout 2020 vv andand 00..55 AA.. SUSSUS isis mainlymainly usedused inin Timing,Timing, logiclogic andand triggertrigger circuitscircuits..
  14. 14. SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch)SUS (Silicon Unilateral Switch) 9/12/2013 Mahesh J. vadhavaniya 14
  15. 15. SCSSCSSCSSCSSCSSCSSCSSCS Silicon Controlled SwitchSilicon Controlled SwitchSilicon Controlled SwitchSilicon Controlled SwitchSilicon Controlled SwitchSilicon Controlled SwitchSilicon Controlled SwitchSilicon Controlled Switch J1J1 J2J2 J3J3 16 9/12/2013 Mahesh J. vadhavaniya 15
  16. 16. SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch) AnAn SCSSCS isis aa tetrodetetrode.. ItIt isis aa fourfour electrodeelectrode thyristorthyristor.. ItIt hashas twotwo gates,gates, oneone anodeanode gategate (AG)(AG) likelike aa PUTPUT andand anotheranother cathodecathode gategate (KG)(KG) likelike anan SCRSCR.. 9/12/2013 Mahesh J. vadhavaniya 16 AnAn SCSSCS isis aa fourfour layer,layer, fourfour terminalterminal pnpnpnpn devicedevice withwith anodeanode A,A, cathodecathode K,K, anodeanode gategate AGAG andand cathodecathode gategate KGKG.. AnAn SCSSCS cancan bebe turnedturned onon byby eithereither gategate..
  17. 17. SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch) J1J1 9/12/2013 Mahesh J. vadhavaniya 17 J2J2 J3J3
  18. 18. SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch) WhenWhen aa negativenegative pulsepulse isis appliedapplied toto gategate AG,AG, junctionjunction JJ11 isis forwardforward biasedbiased andand SCSSCS isis turnedturned onon.. AA positivepositive pulsepulse atat AGAG willwill reversereverse biasbias junctionjunction JJ11 andand turnsturns offoff thethe SCSSCS.. WhenWhen aa positivepositive pulsepulse isis appliedapplied toto gategate KG,KG, junctionjunction JJ22 9/12/2013 Mahesh J. vadhavaniya 18 WhenWhen aa positivepositive pulsepulse isis appliedapplied toto gategate KG,KG, junctionjunction JJ22 isis forwardforward biasedbiased andand SCSSCS isis turnedturned onon.. (Just(Just likelike anan SCR)SCR) AA negativenegative pulsepulse atat KGKG willwill reversereverse biasbias junctionjunction JJ22 andand turnsturns offoff thethe SCSSCS.. (Just(Just likelike aa GG..TT..OO..)) ItsIts ratingsratings areare aboutabout 100100 vv andand 200200 mAmA.. ItIt cancan bebe operatedoperated likelike anan OROR gategate..
  19. 19. SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch) ApplicationsApplications Timing,Timing, logiclogic andand triggeringtriggering circuitscircuits PulsePulse generatorsgenerators 9/12/2013 Mahesh J. vadhavaniya 19 PulsePulse generatorsgenerators VoltageVoltage sensorssensors OscillatorsOscillators etcetc..
  20. 20. SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch)SCS (Silicon Controlled Switch) 9/12/2013 Mahesh J. vadhavaniya 20
  21. 21. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC TRIodeTRIodeTRIodeTRIodeTRIodeTRIodeTRIodeTRIode and ACand ACand ACand ACand ACand ACand ACand AC 9/12/2013 Mahesh J. vadhavaniya 21
  22. 22. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC AnAn SCRSCR isis aa unidirectionalunidirectional devicedevice asas itit cancan conductconduct onlyonly fromfrom anodeanode toto cathodecathode onlyonly andand notnot fromfrom cathodecathode toto anodeanode.. AA TriacTriac cancan conductconduct inin bothboth thethe directionsdirections.. AA TriacTriac isis aa bidirectionalbidirectional thyristorthyristor withwith threethree terminalsterminals.. 9/12/2013 Mahesh J. vadhavaniya 22 ItIt isis usedused extensivelyextensively forfor thethe controlcontrol ofof powerpower inin acac circuitscircuits.. WhenWhen inin operation,operation, TriacTriac isis equivalentequivalent toto twotwo SCRsSCRs connectedconnected inin antiparallelantiparallel.. AA TriacTriac isis aa bidirectionalbidirectional thyristorthyristor withwith threethree terminalsterminals..
  23. 23. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC TriacTriac isis bidirectionalbidirectional devicedevice (can(can conductconduct currentcurrent inin eithereither direction)direction) ,, whilewhile SCRSCR isis unidirectionalunidirectional devicesdevices (can(can conductconduct currentcurrent onlyonly inin oneone way)way).. DifferencesDifferences betweenbetween TriacTriac andand SCRSCR 9/12/2013 Mahesh J. vadhavaniya 23 TRIACsTRIACs cancan bebe triggeredtriggered byby eithereither aa positivepositive oror aa negativenegative currentcurrent appliedapplied toto itsits gategate electrodeelectrode whilewhile SCRSCR cancan onlyonly triggeredtriggered whenwhen aa positivepositive currentcurrent applyapply toto thethe gategate terminalterminal ForceForce commutationcommutation byby reversedreversed biasingbiasing cannotcannot bebe employedemployed..
  24. 24. ComparisonComparisonComparisonComparisonComparisonComparisonComparisonComparison between SCR and TRIACbetween SCR and TRIACbetween SCR and TRIACbetween SCR and TRIACbetween SCR and TRIACbetween SCR and TRIACbetween SCR and TRIACbetween SCR and TRIAC 9/12/2013 Mahesh J. vadhavaniya 24
  25. 25. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC 9/12/2013 Mahesh J. vadhavaniya 25
  26. 26. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC 9/12/2013 Mahesh J. vadhavaniya 26
  27. 27. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC AsAs thethe triactriac cancan conductconduct inin bothboth thethe directions,directions, thethe termsterms anodeanode andand cathodecathode areare notnot applicableapplicable toto triactriac.. ItsIts threethree terminalsterminals areare usuallyusually designateddesignated asas MTMT11 (main(main terminalterminal 11),), MTMT22 andand thethe gategate GG.. WithWith nono signalsignal toto gate,gate, thethe triactriac willwill blockblock bothboth halfhalf cyclescycles ofof thethe acac appliedapplied voltagevoltage inin casecase peakpeak valuevalue ofof thisthis 9/12/2013 Mahesh J. vadhavaniya 27 TheThe triactriac cancan bebe turnedturned onon inin eacheach halfhalf cyclecycle ofof thethe appliedapplied voltagevoltage byby applyingapplying aa positivepositive oror negativenegative voltagevoltage toto thethe gategate withwith respectrespect toto terminalterminal MTMT11.. MTMT11 isis takentaken asas thethe pointpoint forfor measuringmeasuring thethe voltagevoltage andand currentcurrent isis measuredmeasured atat thethe gategate andand MTMT22 terminalsterminals.. cyclescycles ofof thethe acac appliedapplied voltagevoltage inin casecase peakpeak valuevalue ofof thisthis voltagevoltage isis lessless thanthan thethe breakdownbreakdown voltagevoltage ofof VVBB0101 andand VVBB0202 ofof thethe triactriac..
  28. 28. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC 9/12/2013 Mahesh J. vadhavaniya 28
  29. 29. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC 9/12/2013 Mahesh J. vadhavaniya 29
  30. 30. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Characteristics…Characteristics…Characteristics…Characteristics…Characteristics…Characteristics…Characteristics…Characteristics… ItIt cancan bebe seenseen thatthat itit isis anan extensionextension IVIV characteristiccharacteristic ofof SCRSCR.. TheThe characteristiccharacteristic areare symmetricalsymmetrical aboutabout thethe firstfirst andand thethe thirdthird quadrantsquadrants.. 9/12/2013 Mahesh J. vadhavaniya 30 ItIt showsshows thethe gategate cancan bebe usedused toto controlcontrol thethe mainmain currentcurrent flowflow inin eithereither directiondirection.. TRIACTRIAC willwill bebe continuouslycontinuously ONON untiluntil thethe currentcurrent throughthrough AA11 toto AA22 areare belowbelow thethe holdingholding currentcurrent.. thethe thirdthird quadrantsquadrants..
  31. 31. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Triggering Method…Triggering Method…Triggering Method…Triggering Method…Triggering Method…Triggering Method…Triggering Method…Triggering Method… TheThe phasephase shiftingshifting methodmethod ofof firingfiring TRIACTRIAC isis similarsimilar toto thethe firingfiring ofof thethe SCRSCR.. TheThe majormajor differencedifference inin thethe waveformwaveform isis therethere isis aa negativenegative portionportion inin thethe waveformwaveform ofof TRIACTRIAC.. ItIt showsshows thethe gategate cancan bebe usedused toto controlcontrol thethe mainmain currentcurrent flowflow inin eithereither directiondirection.. 9/12/2013 Mahesh J. vadhavaniya 31
  32. 32. Turning on the TRIAC…Turning on the TRIAC…Turning on the TRIAC…Turning on the TRIAC…Turning on the TRIAC…Turning on the TRIAC…Turning on the TRIAC…Turning on the TRIAC… 9/12/2013 Mahesh J. vadhavaniya 32
  33. 33. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… N2N2 N2N2 P2P2 MT1MT1 GG N4N4 P1P1 N1P2P2 N4N4 N1 P2P2 N3N3 N3N3 MT2MT2 9/12/2013 Mahesh J. vadhavaniya 33
  34. 34. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… ((ii)) MTMT22 isis positivepositive andand gategate currentcurrent isis positivepositive WhenWhen MTMT22 isis positivepositive withwith respectrespect toto MTMT11,, junctionjunction PP11 NN11,, PP22 NN22 areare forwardforward biasedbiased butbut junctionjunction NN11 PP22 isis revrserevrse biasedbiased.. WhenWhen gategate terminalterminal isis positivepositive withwith respectrespect toto MTMT11,, gategate currentcurrent flowsflows mainlymainly throughthrough PP22 NN22 junctionjunction likelike anan ordinaryordinary SCRSCR.. WhenWhen gategate currentcurrent hashas injectedinjected sufficientsufficient chargecharge intointo PP22 layer,layer, reversereverse biasbias junctionjunction NN11 PP22 breaksbreaks downdown justjust asas inin aa normalnormal SCRSCR 9/12/2013 Mahesh J. vadhavaniya 34 TriacTriac startsstarts conductingconducting throughthrough PP11 NN11 PP22 NN22 layerslayers.. reversereverse biasbias junctionjunction NN11 PP22 breaksbreaks downdown justjust asas inin aa normalnormal SCRSCR ThisThis impliesimplies whenwhen MTMT22 andand gategate areare positivepositive withwith respectrespect toto MTMT11,, traictraic turnsturns onon likelike aa conventionalconventional thyristorthyristor.. InIn thisthis conditioncondition triactriac operatesoperates inin thethe firstfirst quadrantquadrant.. TheThe devicedevice isis moremore sensitivesensitive inin thisthis modemode.. ItIt isis ecommendedecommended methodmethod ofof triggeringtriggering ifif thethe conductionconduction isis requiredrequired inin thethe firstfirst quadrantquadrant..
  35. 35. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… (ii)(ii) MTMT22 isis positivepositive butbut gategate currentcurrent isis negativenegative TriacTriac startsstarts conductingconducting throughthrough PP11 NN11 PP22 NN33 layerslayers initiallyinitially.. WhenWhen gategate terminalterminal isis negativenegative withwith respectrespect toto MTMT11,, gategate currentcurrent flowsflows throughthrough PP22 NN33 junctionjunction andand reversereverse biasedbiased junctionjunction NN11 PP22 isis forwardforward biasedbiased asas inin aa normalnormal thyristorthyristor.. WithWith thethe conductionconduction ofof PP11 NN11 PP22 NN33,, thethe voltagevoltage dropdrop acrossacross thisthis pathpath fallsfalls butbut potentialpotential ofof layerlayer betweenbetween PP22 NN33 risesrises towardstowards thethe anodeanode 9/12/2013 Mahesh J. vadhavaniya 35 pathpath fallsfalls butbut potentialpotential ofof layerlayer betweenbetween PP22 NN33 risesrises towardstowards thethe anodeanode potentialpotential ofof MTMT22.. AsAs thethe rightright handhand portionportion ofof PP22 isis clampedclamped atat thethe cathodecathode potentialpotential ofof MTMT11,, aa potentialpotential gradientgradient existsexists acrossacross layerlayer PP22.. PP22’s’s leftleft handhand regionregion beingbeing atat higherhigher potentialpotential thanthan itsits rightright handhand regionregion.. TheThe currentcurrent isis establishedestablished inin layerlayer PP22 fromfrom leftleft toto rightright.. ThisThis currentcurrent isis similarsimilar toto conventionalconventional gategate currentcurrent ofof anan SCRSCR..
  36. 36. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… (ii)(ii) MTMT22 isis positivepositive butbut gategate currentcurrent isis negativenegative TheThe devicedevice structurestructure PP11 NN11 PP22 NN33 maymay bebe regardedregarded asas pilotpilot SCRSCR andand thethe structurestructure PP11 NN11 PP22 NN22 asas thethe mainmain SCRSCR.. AsAs aa result,result, rightright handhand partpart ofof triactriac consisitingconsisiting ofof mainmain structurestructure PP11 NN11 PP22 NN22 beginsbegins toto conductconduct ItIt cancan bebe statedstated thatthat anodeanode currentcurrent ofof pilotpilot SCRSCR servesserves asas thethe gategate currentcurrent ofof thethe mainmain SCRSCR.. 9/12/2013 Mahesh J. vadhavaniya 36 currentcurrent ofof thethe mainmain SCRSCR.. ThisThis isis lessless sensitivesensitive andand thereforetherefore moremore gategate currentcurrent isis requiredrequired.. TheThe gategate currentcurrent IgIg forwardforward biasesbiases PP22 NN22 junctionjunction LayerLayer NN22 injectsinjects electronselectrons intointo PP22 layerlayer.. AsAs aa resultresult thethe reversereverse biasedbiased junctionjunction NN11 PP11 breaksbreaks downdown asas inin aa conventionalconventional thyristorthyristor.. (iii)(iii) MTMT22 isis negativenegative butbut gategate currentcurrent isis positivepositive
  37. 37. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… AsAs usualusual thethe currentcurrent afterafter turnturn onon isis limitedlimited byby thethe externalexternal loadload.. EventuallyEventually thethe structurestructure PP22 NN11 PP11 NN44 isis completelycompletely turnedturned onon.. AsAs thethe triactriac isis turnedturned onon byby remoteremote gategate NN22,, thethe devicedevice isis lessless sensitivesensitive inin thethe thirdthird quadrantquadrant withwith positivepositive gategate currentcurrent.. (iii)(iii) MTMT22 isis negativenegative butbut gategate currentcurrent isis positivepositive (iv)(iv) BothBoth MTMT22 andand gategate currentcurrent areare negativenegative 9/12/2013 Mahesh J. vadhavaniya 37 InIn thisthis modemode NN33 actsacts asas aa remoteremote gategate.. TheThe gategate currentcurrent IgIg flowsflows fromfrom PP22 toto NN33 asas inin aa normalnormal thyristorthyristor.. ThoughThough thethe triactriac isis turnedturned onon byby remoteremote gategate NN33 inin thirdthird quadrant,quadrant, thethe devicedevice isis moremore sensitivesensitive underunder thisthis conditioncondition comparedcompared withwith turnturn onon actionaction ofof casecase (iii)(iii) ReverseReverse biasedbiased junctionjunction NN11 PP11 isis brokenbroken andand finallyfinally thethe structurestructure PP22 NN11 PP11 NN44 isis turnedturned onon completelycompletely.. (iv)(iv) BothBoth MTMT22 andand gategate currentcurrent areare negativenegative
  38. 38. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC TheThe sensitivitysensitivity ofof thethe triactriac isis greatestgreatest inin thethe firstfirst quadrantquadrant whenwhen turnedturned onon withwith positivepositive gategate currentcurrent andand alsoalso inin thethe thirdthird quadrantquadrant whenwhen turnedturned onon withwith negativenegative gategate currentcurrent.. ConclusionConclusion :: 9/12/2013 Mahesh J. vadhavaniya 38 SoSo thethe triactriac isis rarelyrarely operatedoperated inin firstfirst quadrantquadrant withwith negativenegative gategate currentcurrent andand inin thethe thirdthird quadrantquadrant withwith positivepositive gategate currentcurrent.. TheThe sensitivitysensitivity ofof thethe triactriac isis lowlow inin thethe firstfirst quadrantquadrant whenwhen turnedturned onon withwith negativenegative gategate currentcurrent andand alsoalso inin thethe thirdthird quadrantquadrant whenwhen turnedturned onon withwith positivepositive gategate currentcurrent..
  39. 39. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… AsAs thethe twotwo conductingconducting pathspaths fromfrom MTMT11 toto MTMT22 oror fromfrom MTMT22 toto MTMT11 interactinteract withwith eacheach otherother inin thethe structurestructure ofof thethe triactriac,, theirtheir voltage,voltage, currentcurrent andand frequencyfrequency ratingsratings areare muchmuch lowerlower asas comparedcompared withwith conventionalconventional thyristorsthyristors.. TriacsTriacs areare availableavailable withwith thethe ratingsratings 12001200 vv andand 300300 AA 9/12/2013 Mahesh J. vadhavaniya 39 TriacsTriacs areare extensivelyextensively usedused inin residentialresidential lamplamp dimmers,dimmers, heatheat controlcontrol andand forfor thethe speedspeed controlcontrol ofof smallsmall singlesingle phasephase seriesseries andand inductioninduction motorsmotors.. TriacsTriacs areare availableavailable withwith thethe ratingsratings 12001200 vv andand 300300 AA ((rmsrms))..
  40. 40. TRIACTRIACTRIACTRIACTRIACTRIACTRIACTRIAC –––––––– Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process…Turn ON process… AA triactriac maymay somesome timestimes operateoperate inin thethe rectifierrectifier mode,mode, duedue toto………… (a)(a) ForFor aa givengiven valuevalue ofof positivepositive gategate current,current, aa triactriac maymay turnturn onon withwith MTMT22 positivepositive inin firstfirst quadrantquadrant butbut maymay failfail toto turnturn onon withwith MTMT22 negativenegative.. 9/12/2013 Mahesh J. vadhavaniya 40 (b)(b) WithWith constantconstant negativenegative gategate current,current, aa triactriac maymay turnturn onon withwith MTMT22 negativenegative inin thirdthird quadrantquadrant butbut maymay failfail toto turnturn onon withwith MTMT22 positivepositive.. turnturn onon withwith MTMT22 negativenegative.. TheThe rectifierrectifier modemode cancan bebe overcomeovercome byby increasingincreasing thethe valuevalue ofof gategate currentcurrent..
  41. 41. ASCRASCRASCRASCRASCRASCRASCRASCR Asymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCRAsymmetrical SCR 9/12/2013 Mahesh J. vadhavaniya 41
  42. 42. ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR )ASCR ( Asymmetrical SCR ) AnAn ASCRASCR isis speciallyspecially fabricatedfabricated toto havehave limitedlimited reversereverse voltagevoltage capability,capability, whichwhich permitspermits aa reductionreduction inin turnturn--onon time,time, turnturn--offoff timetime andand onon--statestate voltagevoltage dropdrop inin ASCRASCR.. AA typicaltypical ASCRASCR maymay havehave reversereverse blockingblocking capabilitycapability ofof 2020 toto 3030 VV andand forwardforward blockingblocking voltagevoltage ofof 400400 toto 20002000 VV.. 9/12/2013 Mahesh J. vadhavaniya 42 FastFast turnturn--offoff ASCRsASCRs minimizeminimize thethe size,size, weightweight andand costcost ofof commutatingcommutating componentscomponents andand permitpermit highhigh frequencyfrequency operationoperation (( 2020 KHzKHz oror moremore )) withwith improvedimproved efficiencyefficiency.. 2020 toto 3030 VV andand forwardforward blockingblocking voltagevoltage ofof 400400 toto 20002000 VV.. ASCRsASCRs withwith turnturn--offoff timetime halfhalf ofof thatthat ofof similarsimilar ratesrates conventionalconventional SCRsSCRs havehave beenbeen developeddeveloped..
  43. 43. RCTRCTRCTRCTRCTRCTRCTRCT Reverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse ConductingReverse Conducting ThyristorThyristorThyristorThyristorThyristorThyristorThyristorThyristor 9/12/2013 Mahesh J. vadhavaniya 43
  44. 44. RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor ) RCTRCT isis aa specialspecial casecase ASCRASCR withwith aa monolithicallymonolithically integratedintegrated antiparallelantiparallel diodediode onon thethe samesame siliconsilicon chipchip.. ThisThis constructionconstruction reducesreduces toto zerozero thethe reversereverse blockingblocking capabilitycapability ofof RCTRCT.. 9/12/2013 Mahesh J. vadhavaniya 44 capabilitycapability ofof RCTRCT.. AA currentcurrent pulsepulse throughthrough thethe diodediode partpart ofof thethe chipchip turnsturns offoff RCTRCT.. TheThe arrangementarrangement ofof ASCRASCR andand diodediode inin aa singlesingle devicedevice reducesreduces thethe heatheat sinksink sizesize andand leadsleads toto compactnesscompactness ofof thethe converterconverter..
  45. 45. RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor )RCT ( Reverse Conducting Thyristor ) TheThe undesirableundesirable straystray looploop inductanceinductance betweenbetween ASCRASCR andand diodediode isis alsoalso eliminatedeliminated andand unwantedunwanted reversereverse voltagevoltage transientstransients acrossacross ASCRASCR areare avoidedavoided.... ThisThis leadsleads toto betterbetter turnturn offoff behaviourbehaviour ofof RCTRCT.. 9/12/2013 Mahesh J. vadhavaniya 45 ThisThis leadsleads toto betterbetter turnturn offoff behaviourbehaviour ofof RCTRCT.. RCTsRCTs withwith 20002000 VV andand 500500 AA ratingsratings areare availableavailable.. ForFor highhigh performanceperformance inverterinverter andand chopperchopper circuits,circuits, RCTsRCTs cancan nownow bebe tailortailor--mademade..
  46. 46. 9/12/2013 Mahesh J. Vadhavaniya 47

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