Introduction
High-powertransistorsaregenerallycalledpowerdevices,whichbelongtothefieldofpowerelectronicstechnology(powerelectronicstechnology).Itsessenceistoeffectivelycontrolthereasonableoperationofpowerelectronicdevices,andprovidehigh-poweroutputfortheloadthroughpowerelectronicdevices.
Generallyspeaking,powerdevicesusuallyworkunderhighvoltageandhighcurrentconditions,andgenerallyhavethecharacteristicsofhighwithstandvoltage,largeworkingcurrent,andlargeself-dissipationpower.Therearecertaindifferencesinpowerdevices.
Classification
Powerdevicesasawholecanbedividedintouncontrollabledevices,semi-controllabledevicesandfullycontrollabledevices.
1.Uncontrollabledevices
Guideonandoffcannotbecontrolledbycontrolsignals,itiscompletelydeterminedbythecurrentandvoltageconditionsitbearsinthecircuit,whichbelongstonaturalconductionAndnaturalshutdown.Includingpowerdiodes.
2.Semi-controllabledevice
Itreferstothecontrolsignalcanbeusedtocontrolitsturn-on,butcannotcontrolitsturn-off,itsturn-offcanonlybewithstoodinthemaincircuitThevoltageandcurrentconditionsaredeterminedbynaturalshutdown.Includingthethyristor(SCR)andthebidirectionalthyristor(TRIAC)derivedfromit.
3.Fullycontrollabledevices
referstodevicesthatcanbeturnedonandoffusingcontrolsignals,includingpowertransistors(GTR),powerfieldeffecttransistors(powerMOSFET),Turnoffthyristor(GTO),insulatedgatebipolartransistor(IGBT),MOScontrolledthyristor(MCT),staticinductiontransistor(SIT),staticinductionthyristor(SITH)andintegratedgatecommutatedthyristor(IGCT),etc.
Fullycontrollabledevicescanalsobedividedintotwocategories:currentcontroltypeandvoltagecontroltype.
Thecurrentcontroltypeincludes:GTR(powertriode),SCR(controllablethyristor),TRIAC(controllablebidirectionalthyristor),GTO(turnofftransistor)andsoon.
Thevoltagecontroltypeincludes:powerMOSFET,IGBT,MCTandSIT.
Performancecomparison
1.Selectionprinciple
Applicability(whethertechnicalrequirementsaremet),economy(cost-effectiveness);
2.Operatingfrequencycomparison
SIT>MOSFET(3-10MHz)>IGBT(50kHz)>SITH>GTR(30kHz)>MCT>GTO;
3.Powercapacitycomparison
GTO(6000V/6000A)>SITH>MCT>IGBT(2500V/1000A)>GTR(1800V/400A)>SIT>powerMOSFET(1000V/100A);
p>4.Comparisonofon-stateresistance
PowerMOSFET>SIT>SITH>GTO>IGBT>GTR>MCT;
5.Comparisonofcontroldifficulty
Voltagecontroltypecontroliseasiertocontrolthancurrentcontroltype,buttheSITisanormally-ondevice,andthecontrolismoredifficultthanpowerMOSFETandIGBT.
Designprinciplesofbasedrivecircuit
GTRbasedrivecircuitandperformancedirectlyaffecttheworkingconditionsofGTR,sothefollowingtwopointsshouldbeconsideredwhendesigningthebasedrivecircuit:Optimizeddrivingmodeandautomaticfastprotection.
Theso-calledoptimaldriveistocontroltheswitchingprocessoftheGTRwiththeidealbasedrivecurrentwaveforminordertoincreasetheswitchingspeedandreducetheswitchingloss.Idealbasedrivecurrentwaveform.Inordertospeeduptheturn-ontimeandreduceturn-onloss,theforwardbasecurrentnotonlyrequiresasteepleadingedgeintheinitialturn-onperiod,butalsorequiresacertainperiodofoverdrivecurrentIB1.ThebasedrivecurrentIB2intheturn-onphaseshouldkeeptheGTRjustinthequasi-saturatedstate,soastoshortenthestoragetimets.Ingeneral,thevalueofoverdrivecurrentIB1isselectedtobeabout3timesthevalueofquasi-saturatedbasedrivecurrentIB2,theleadingedgeoftheoverdrivecurrentwaveformshouldbecontrolledwithin0.5s,anditswidthshouldbecontrolledatabout2s.WhentheGTRisturnedoff,thereversebasedrivecurrentIB3shouldbelarger,inordertospeedupthecarrierextractionspeedinthebasearea,shortentheturn-offtime,andreducetheturn-offloss.Inpracticalapplications,oftenchooseIB3=IB1orBigger.ThiskindofbasedrivewaveformisgenerallyrealizedbyanaccelerationcircuitandaBakerclampcircuit.
Inaddition,theGTRdrivecircuitshouldalsohaveaself-protectionfunction,sothatthebasedrivesignalcanbequicklyandautomaticallycutoffinafaultstatetoavoiddamagetotheGTR.Therearemanytypesofprotectioncircuits,whichcanbeselectedappropriatelyaccordingtothedifferentrequirementsofdevicesandcircuits.Inordertoimprovetheswitchingspeed,ananti-saturationprotectioncircuitcanbeused;toensurethattheswitchingcircuititselfhaslowpowerconsumption,adesaturationprotectioncircuitcanbeused;topreventunder-drivingthebasefromcausingthedevicetobeoverloaded,apowersupplyvoltagemonitoringprotectioncanbeused.Inaddition,therearepulsewidthlimitingcircuitsandprotectioncircuitsforovervoltage,overcurrent,andoverheatingtopreventdamagetotheGTR.
Therearemanyformsofbasedrivecircuit,andtherearethreeobvioustrendsinthesummary:
1.Inordertoimprovetheworkingspeed,anti-saturationBakerclampcircuitisusedasthebasiccircuit;
2.Continuouslyimproveandexpandtheautomaticprotectionfunction;
3.Continuouslyimproveandperfectintermsofturn-onandturn-offspeed.
Applications
Usedtocontrolpoweroutput,high-frequencyhigh-powertransistorapplicationsinthescanningcircuitofelectronicequipment,suchascolorTV,monitors,oscilloscopes,horizontalscanningcircuitsoflargegamemachines,Videoamplifiercircuit,poweramplifieroftransmitter,suchasradiofrequencyoutputcircuitofwalkie-talkie,mobilephone,high-frequencyoscillationcircuitandhigh-speedelectronicswitchcircuit,etc.
Thehigh-powertubemustbeinstalledonametalradiatorbecauseitgeneratesalargeamountofheat,andtheareaofthemetalradiatormustbelargeenough,otherwisethetechnicalperformancespecifiedinthetechnicaldocumentationwillnotbeachieved.