lab 5 pulse width modulation

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1、TEXASA&MUNIVERSITYENGR111B:FoundationsofElectrical&ComputerEngineeringLab5:PulseWidthModulationTeamMembers:__________________________________________________SectionNumber:__________TeamNumber:__________ThisLabisduebytheBeginningoftheNextLabSession.WrittenBy:HankWalkerLorneLiechty15WrittenbyTexas

2、A&MUniversityLab5:PulseWidthModulationTimeLimit:1weekOVERVIEWUsingRCcircuitswecannotonlytimeindividualevents,butwecanalsocreaterepeatingtimers.Thisoscillatorytimingisusedinvirtuallyeveryelectronicdeviceavailable.InthislabstudentswillexaminetheuseofadigitallyoscillatingsignaltocontrolDCmotorspeed

3、.Thisapproachcontrastswiththesimpleresistor-basedcurrentlimitingmethodyouusedpreviously.Topicscoveredinthislabincludethefollowingmaterial:-DigitallyOscillatingSignals-PulseWidthModulation-AverageVoltage,Current,andPower-HowaPWMsignalcanbegeneratedusinga555timer-Diodes-PWMSignalControlofDCMotorBA

4、CKGROUNDToassiststudentsincompletingtheexercisesrequiredbythislab,thefollowingbackgroundinformationhasbeenprovided.Itisrecommendedthateachstudentreadallofthefollowinginformationasabeneficialreviewofthetopicsrequired.DIGITALOSCILLATIONSAnoscillatingsignalisonewhichchangesbetweentwolevelsaccording

5、toaregularpatternofintervals.AC(AlternatingCurrent)voltagesareincludedintherealmofoscillatingvoltages,butthetermACisreservedforsignalswhichincludebothpositiveandnegativevoltages.Adigitaloscillationalsoswitchesbetweentwolevelsaccordingtodefinedintervals,andtheidealdigitalsignalexistsonlyatthespec

6、ifiedlevelsanddoesnotexistatthelevelsinbetween.ThesignalsrepresentedinFiguresB1aretwodifferentdigitallyoscillatingsignals.FigureB1:DigitallyOscillatingSignals15WrittenbyTexasA&MUniversityExaminingthesignalsinFigureB1,noticethatthelowerofthetwovoltagesdoesnothavetobesettozerovolts,orground;thelow

7、ervoltageofadigitalsignalisdefinedtobealogicalLOWor0,butthevalueisnotrequiredtobezero.WhenasignalisnotcenteredaroundzerothesignalissaidtohaveaDCoffsetthatraisesorlowersthesignaltoanewcentervoltage.SignalsthatdonothaveDCoffse