第10章 直流无刷电机

IntroductionBLDCmotorsareoneofthemotortypesrapidlygainingpopularity.BLDCmotorsareusedinindustriessuchasAutomotive,Aerospace,Consumer,Medical,IndustrialAutomationEquipmentandInstrumentation.Asthenameimplies,BLDCmotorsdonotusebrushesforcommutation;instead,theyareelectronicallycommutated.BrushlessDCelectricmotor(BLDCmotors)alsoknownaselectronicallycommutatedmotorsaresynchronousmotorsthatarepoweredbyaDCelectricsourceviaaninverter,whichproducesanACelectricsignaltodrivethemotor(AC,alternatingcurrent,doesnotimplyasinusoidalwaveformbutratherabi-directionalcurrentwithnorestrictiononwaveform);additionalsensorsandelectronicscontroltheinverteroutputamplitudeandwaveformandfrequency(i.e.rotorspeed).ABrushlessDCmotorconsistsofthreeparts,amotor,therotorpositionsensorsandelectronicswitchingcircuit.principleblockdiagramofabrushlessDCmotorisshowninfig.10-1.DCpowersupplySwitchingcircuitMotorPositionSensorOutputFig.10-1principleblockdiagramofbrushlessDCmotors翻译直流电机的电机类型之一的迅速普及。BLDC电机应用在如汽车，航空航天，消费，医疗行业，工业自动化设备及仪表。顾名思义，BLDC电机不使用电刷换向；相反，它们是电子换向。无刷直流电机（BLDC电机）也被称为电子换向电机同步电机，由直流电源通过逆变器驱动电机，产生交流电信号（交流，交流，并不意味着一个正弦波形而对波形没有限制双向电流）；附加传感器和电子控制的逆变器输出的幅值、波形和频率（即转速）。BLDCmotorshavemanyadvantagesoverbrushedDCmotorsandinductionmotors.Afewoftheseare:直流电机在直流有刷电机和感应电机有许多优点。这些都是一些：•Betterspeedversustorquecharacteristics更好的速度和转矩特性•Highdynamicresponse高动态响应•Highefficiency效率高•Longoperatinglife寿命长•Noiselessoperation无声运行•Higherspeedranges•高速范围Inaddition,theratiooftorquedeliveredtothesizeofthemotorishigher,makingitusefulinapplicationswherespaceandweightarecriticalfactors.Wewilldiscussindetailtheconstruction,workingprinciple,characteristicsandtypicalapplicationsofBLDCmotors.此外，通过向电动机转矩的大小比例较高，使得它在空间和重量是关键因素的应用。我们将详细讨论的结构，工作原理及典型应用，直流电机的特点。10.2FUNDAMENTALCONSTRUCTIONANDOPERATINGPRINCIPLE基本结构和工作原理BLDCmotorsareatypeofsynchronousmotor.Thismeansthemagneticfieldgeneratedbythestatorandthemagneticfieldgeneratedbytherotorrotatesatthesamefrequency.BLDCmotorsdonotexperiencethe“slip”thatisnormallyseenininductionmotors.BLDCmotorscomeinsingle-phase,2-phaseand3-phaseconfigurations.Correspondingtoitstype,thestatorhasthesamenumberofwindings.Outofthese,3-phasemotorsarethemostpopularandwidelyused.直流电机是一种同步电机。这意味着由转子产生的磁场与定子所产生的磁场，在相同的频率旋转。BLDC电机不经历“滑”即是在感应电动机通常看到的。直流电机是单相，两相和三相配置。相应的类型，定子绕组相同数量。从这些，三相异步电动机是最流行和广泛使用的。10.2.1CONSTRUCTIONFigure10-2Construction1)StatorThestatorofaBLDCmotorconsistsofsteellaminationswithwindingsplacedintheslotsthatareaxiallycutalongtheinnerperiphery.Traditionally,thestatorresemblesthatofaninductionmotor;however,thewindingsaredistributedinadifferentmanner.MostBLDCmotorshavethreestatorwindingsconnectedinstarfashion.Eachofthesewindingsareconstructedwithnumerouscoilsinterconnectedtoformawinding.OneormorecoilsareplacedintheslotsandtheyareFigure10-3Statorinterconnectedtomakeawinding.Eachofthesewindingsaredistributedoverthestatorperipherytoformanevennumbersofpoles.Figure10-3一台电机的定子由钢叠片放置在沿内周轴向切槽绕组。传统上，定子类似于一个感应电动机；然而，绕组分布在不同的方式。大多数的BLDC电机有三个定子绕组的星形连接方式。这些众多的线圈绕组连接成一个绕组构造。一个或多个线圈被放置在插槽中，他们相互连接，使绕组。这些绕组分布在定子的外围形成一个偶数极。图10-3Thearmaturewindingconnectionsareshowninfigure10-4.(a)3-phase,star,3-state;(b)4-phase,star,4-state(c)3-phase,star,6-state(d)2-phase,orthogonal,4-state

Figure10-4Armaturewindingconnection (e)3-phase,delta,6-state;(f)4-phase,closed,4-state2)RotorThefollowingfigure10-6showscrosssectionsofdifferentarrangementsofmagnetsinarotor.Figure10-6UnlikeabrushedDCmotor,thecommutationofaBLDCmotoriscontrolledelectronically.TorotatetheBLDCmotor,thestatorwindingsshouldbeenergizedinasequence.Itisimportanttoknowtherotorpositioninordertounderstandwhichwindingwillbeenergizedfollowingtheenergizingsequence.RotorpositionissensedusingHalleffectsensorsembeddedintothestator.不像有刷直流电机，一台电机的换相控制电子。对BLDC电机旋转，定子绕组应在顺序通电。重要的是要知道为转子位置，了解哪些绕组将通电后，通电顺序。转子位置检测采用霍尔传感器嵌入定子。3)HallSensorsMostBLDCmotorshavethreeHallsensorsembeddedintothestatoronthenon-drivingendofthemotor.WhenevertherotormagneticpolespassneartheHallsensors,theygiveahighorlowsignal,indicatingtheNorSpoleispassingnearthesensors.BasedonthecombinationofthesethreeHallsensorsignals,theexactsequenceofcommutationcanbedetermined.大多数的BLDC电机有三个霍尔传感器嵌入定子在电机的非驱动端。当转子的磁极通过附近的霍尔传感器，他们给一个高或低信号，指示的N或S极附近时，传感器。基于这三个霍尔传感器信号的组合，变换的精确序列可以确定。(4)Electro-magneticpositionsensor10.2.2TheoryofOperation1)Theoperationprincipleof3-phase,star,3-statesystemisexplainedwithfigure8.Figure10-8OperationprincipleTable10-1Conductionsequencetableof3-phase,star,3-statesystemFigure10-9PhasevoltageswaveformsofBLDCFig.10-10Torquewaveform2)3-phase,star,bridgeconnectionFig.10-123-phase,star,bridgeconnectionV1V6(A+C-)→V6V2(B+C-)→V2V4(B+A-)→V4V3(C+A-)→V3V5(C+B-)→V5V1(A+B-)→V1V6(A+C-)Table10-2Conductionsequencetableof2-phase,star,3-phase,6-statesystemFigure10-13Torquevectordiagram3)3-phase,closed,bridgeconnection.Figure10-143-phase,closed,bridgeconnectionV1V6[A//(C→B)]→V6V2[B//(C→A)]→V2V4[C//(B→A)]→V4V3[A//(B→C)]→V3V5[B//(A→C)]→V5V1[C//(A→B)]→V1V6[A//(C→B)]Table10-3Conductionsequencetableofclosed,star,6-statesystem10.3COMPARINGBLDCMOTORSTOOTHERMOTORTYPESComparedtobrushedDCmotorsandinductionmotors,BLDCmotorshavemanyadvantagesandfewdisadvantages.Brushlessmotorsrequirelessmaintenance,sotheyhavealongerlifecomparedwithbrushedDCmotors.BLDCmotorsproducemoreoutputpowerperframesizethanbrushedDCmotorsandinductionmotors.Becausetherotorismadeofpermanentmagnets,therotorinertiaisless,comparedwithothertypesofmotors.Thisimprovesaccelerationanddecelerationcharacteristics,shor