闭环三相异步电动机的串级调速的基本原理与实现方法

沈阳航空工业学院北方科技学院毕业设计（论文）I摘要本文所讨论的是双闭环三相异步电动机的串级调速的基本原理与实现方法。对于一般交流电动机的调速，我们都是从电动机的定子侧引入控制变量（改变定子供电电压、频率）来实现的，这对于转子处于短路状态的交流鼠笼型转子异步电动机是唯一途径。但是，对于绕线式异步电动机来说，由于改变其转子绕组控制变量以实现调速，转子侧的控制变量有电流、电动势、电阻等。通常转子电流随负载的大小决定，不能任意调节；而转子回路阻抗的调节属于耗能型调速，缺点较多，所以转子侧的控制变量只能是电动势，这也是本文所要讨论的重点之一。在发挥绕线式异步电动机转子的可控性优势的基础上，提高调速性能需要从两方面着手：1从节能角度考虑，应将损耗在转子附加电阻上的能量吸收，转化成别的有用的能量或反馈到电网，以提高传动系统的效率。2从高性能调速要求考虑，应用控制理论，将其组成闭环调速控制系统，满足调速精度、动态响应等指标的要求。综合所述，利用串级调速系统，就是使绕线式异步电动机实现高性能调速的有效办法。用转子串反电动势来代替电阻，吸收转差功率；用双闭环控制提高系统的静、动态性能。把这种用附加电动势的方法将转差功率回收利用的调速称为双闭环串级调速。这是本文所必须讨论的，也是本文的核心所在。关键字：双闭环、串级、调速沈阳航空工业学院北方科技学院毕业设计（论文）IIAbstractThispaperdiscussesthemechanismsandimplementationdetailsofconcatenationcontrolinathree-phaseasynchronousmotorwithdoubleclosedloop.Tocontrolspeedsforatypicalalternatingcurrentmotor,weusuallytakecontrolvariables(tochangevoltageandfrequencyofthestatorpowersupply)fromthestatorsideinanelectricmotor,whichisalsotheonlywayforsquirrel-cageasynchronousmotorwithrotorinashort-circuitstate.However,withwoundrotorseries,asynchronousmotorscanadjustspeedsthroughcontrolvariables,whichincludeelectriccurrent,electromotiveforceandresistance,etc.ontherotorside.Typically,therotorcurrentisdeterminedbytheloadandcannotbeadjustedfreely.Incontrast,adjustingrotor’sreturncircuitimpedancetendstoconsumemorepoweralongwithotherdisadvantages.Therefore,electromotiveforceshouldbetheonlycontrolvariableontherotorside,whichisalsooneofthemajorpointsdiscussedinthispaper.Inordertoincreasespeedcontrol,weneedtotakethefollowingtwomeasureswhilefullyutilizingtheadjustablenatureofrotorsinseries-woundasynchronousmotor:1.Inordertosaveenergy,powerwastedonrotor’sadditionalresistanceshouldbeabsorbedandconvertedintootherformsofusableenergyorsentbacktoelectricgridtoincreasetheefficiencyoftransmissionsystems.2.Consideringhighcontrolabilityandtheappliedcontroltheory,itshouldbeformedintoaclosed-loopcontrolsysteminordertomeettherequirementsofsuchcriteriaascontrolaccuracyanddynamicresponse.Insummary,concatenationcontrolsystemisoneeffectivemeanstorealizehighcontrolabilityinseries-woundasynchronousmotors.Specifically,itisusedtoreplaceresistancewithrotor’selectromotiveforceandabsorbslippower;andtoenhancethestaticanddynamiccapabilitiesofthesystemusingdoubleclosedloop.Werefertothismethodofutilizingadditionalelectromotiveforcetorecycleslippowerasconcatenationcontrolwithdoublecloseloop,whichisalsothefocusofthispaper.Keywords:double-loop,cascade,governor沈阳航空工业学院北方科技学院毕业设计（论文）III目录引言...................................................................................................................................11.串级调速的原理................................................................................................................31.1异步电动机转子附加电动势时的工作情况..........................................................31.2串级调速的功率传递关系......................................................................................41.3串级调速系统及其附加电动势的获得..................................................................52.双闭环串级调速系统硬件设计........................................................................................82.1串级调速系统设计..................................................................................................82.2双闭环系统设计......................................................................................................92.3实验调试................................................................................................................103.实验数据分析..................................................................................................................123.1三相异步电动机串级调速开环工作机械特........................................................123.2三相异步电动机单闭环ASR系统静特性..........................................................133.2.1有静差..........................................................................................................133.2.2无静差..........................................................................................................153.3双闭环串级调速系统的静态和动态特性............................................................163.3.1双闭环调速系统的静态特性分析..............................................................163.3.2双闭环调速系统的动态特性分析..............................................................173.4测量直流测速发电机的工作特性........................................................................204.双闭环串级调速系统电路图..........................................................................................23毕设总结.............................................................................................................................24参考文献.............................................................................................................................25附录一双闭环串级调速系统的各个模块的工作原理及功能介绍...............................26附录二双闭环串级调速系统的系统整定.......................................................................35附录三元器件的使用清单...............................................................................................37沈阳航空工业学院北方科技学院毕业设计（论文）1引言电力传动自动控制系统是把电能转换成机械能的装置。它广泛应用在精密设备和精密机构、加工和再加工机器以及运输工具中，也广泛应用在原材料工业以及其他工业部门的传送、预选、一般生产装置和辅