第六章磁敏材料及器件【霍尔,磁阻】【英】ppt课件.ppt

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1、HalleffectTheStaticcurrentcarryingconductorwasputinmagneticfields.Whenthecurrentdirectionwasinconsistentwiththemagneticfielddirection,onthecurrent-carryingconductorelectromotiveforcewasgeneratedbetweenbothsidesoftheparallelcurrentandmagneticfielddirection.Thephenomen

2、onwasknownastheHalleffect.ItwasHallelectricpotential.fl=e·B·v二、TheapplicationofHallsensor1.HallmicrodisplacementsensorHallelementhastheadvantagesofsimplestructure,smallsize,gooddynamiccharacteristicsandlonglife.Itisnotonlyusedtomeasurethemagneticfluxdensity,activep

3、owerandenergyparameters,butalsowidelyusedinthedisplacementmeasurement.Fig.7-12showsthenumberofworkprincipleschematicofHalldisplacementsensors.Fig.(a)istwoidenticalmagneticfieldstrengthpermanentmagnets,thesamepolarityplacingopposite,theHallelementbeinginthemiddleoftw

4、omagnets.二、TheapplicationofHallsensor1.HallmicrodisplacementsensorBecausethemagneticinductionintensityinthemiddleofthemagnetisB=0,theHallpotentialUHoutputfromHallelementisalsozero.ThenthedisplacementisΔx=0.IftheHallelementhasarelativedisplacementinthetwomagnets,the

5、magneticfluxdensityoftheHallelementalsowillchange.ThentheUHisnotzero,whichsizewillreflecttherelativepositionchangesbetweentheHallelementandthemagnet.Thisstructuresensorhasthedynamicrangeupto5mm,andtheresolutionis0.001mm.UH∝KxHallelementHallelementHallelementFig.7-12

6、TheworkingprincipleofHalldisplacementsensorFig.(b)showsasimplestructureHalldisplacementsensor,whichisasensorconsistofapermanentmagnetmagneticcircuit.WhenΔx=0,theHallvoltageisnotzero.Fig.(c)isaHalldisplacementsensorcomposedoftwosamestructuremagneticcircuits.Inordertoo

7、btainabetterlineardistribution,themagneticpoleendiswiththepoleshoe.AdjustingtheinitialpositionoftheHallelements,HallvoltageisUH=0.Thissensorhasahighsensitivity,butthedetectingamountofdisplacementissmall.Itissuitableformeasuringmicro-displacementandvibration.2.Hallrot

8、atespeedsensorFig.7-13isseveraldifferentstructureHallrotatespeedsensors.Theinputshaftandthemeasuredshaftofmagneticwheelareconnecte