第4章交流电力控制电路和交交变频电路

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1、第4章交流电力控制电路和交交变频电路Chapter4acpowercontrolcircuitandalternatingcurrentfrequencyconvertercircuitThelampispoweredbyasinglephasealternatingcurrentregulatingcircuit・Thelampcanberegardedasaresistanceloadandoutputswhen=0Powerismaximum,andthepoweris80%ofthemaximumoutputpower,50%oftheopeningAngle・Solution:th

2、eoutputvoltagewhen=0isthemaximumUomax=ThisisthemaximumloadcurrentIomax=SothemaximumoutputiszeroTheoutputpoweris80%ofthemaximumoutputpower.Pmax=UomaxIomax=Atthispoint,Uo=AndbytheUo二U1CansolveInthesameway,theoutputpoweris50%ofthemaximumoutputpower・Uo二AndbytheUo二U1Whatisthedifferencebetweenthe4.2volta

3、gecircuitandtheacpowercircuit?Whatkindofloadaretheyusing?why?■A:thecircuitofalternatingvoltageandaccircuitisidenticalintheformofcircuit・Thedifferencebetweenthetwoisthatthecontrolmethodisdifferent・Acvoltagecircuitiscontrolledbytheoutputvoltagewaveformateachperiodofacpowersupply.Andacadjustablepowerc

4、ircuitistoloadseveralwaveconnectedwithacpower,andthendisconnectseveralfrequency,bychangingtheswitchingfrequencyanddisconnectthenumberoffrequencyratiotoadjusttheaveragepowerconsumedbyaload.Theacvoltagecircuitiswidelyusedforlightingcontrol(suchasdiiiuninglampandstagelightingcontrol)andthesoftstarting

5、oftheasynchronousmotor,andalsoforthespeedadjustmentoftheasynchronousmotor.Inthepowersupplysystem,itisalsousedforcontinuousadjustmentofreactivepower・Inaddition,inhighvoltagesmallcurrentorlowvoltagelargecurrentdepowersource,thevoltageoftransformerisalsousedtoadjusttransformervoltage・Iftherectifiercir

6、cuitiscontrolledbyathyristor,thehighvoltagesmallcurrentcontrolleddepowersupplyrequiresmanythyristorseries・Similarly,lowvoltagelargecurrentdepowerrequiresmanythyristorparalle1.Thisisallveryunreasonable・Adoptacvoltageregulationcircuitinthetransformerprimarysidevoltageregulation,thevoltageandcurrentva

7、lueisnottoobignortoosmall,thetransformersecondarysidejustusedioderectifier・Suchcircuitsaresmall,low-costandeasytodesign.Theacpowercircuitisoftenusedforcontrollingthetemperatureoftheelectricstove・Becausethet