2015电大《电气传动与调速系统》期末复习试题及参考答案

电大电气传动与调速系统试题一、选择题（每题2分，共10分）1他励式直流电动机在制动方法中哪种方法的方程式与电动状态时的方程式相同（A）A反馈制动B电源反接C能耗制动D以上都是2哪种电动机的机械硬度最大（C）A直流电动机B三相异步电动机C同步电动机3在三相异步电动机的调速方法中，哪种方法最复杂（D）A调压调速B转子电路串电阻调速C变极调速D变频调速4三相异步电动机定子旋转磁场的转速与转子的转速之间的相互关系是（A）A定子旋转磁场转速大于转子的转速B定子旋转磁场转速等于转子的转速C定子旋转磁场转速小于转子的转速D定子旋转磁场转速是转子的转速的2倍二、判断题（每题1分，共计10分）1机械效率影响电动机与生产机械之间的速度传动关系。（错误）2在正常情况下同步电动机的机械硬度是绝对硬特性的。（正确）3直流电动机的调速范围只有在静差率一定的条件下才有意义。（正确）4电动机的速度调节与速度变化的含义是相同的。（错误）5在改变极对数调速中，YYY方法具有恒转矩调速性质。（正确）6三相异步电动机能耗制动的强弱程度只与所通直流电流大小有关。（错误）7同步电动机的整个旋转磁场都是由定子电路产生的。（错误）三、填空题（每空1分，共10分）1在多轴系统中负载转矩和飞轮转矩的折算原则分别是功率守恒、能量守恒。2限制直流电动机的启动电流，一般有外串电阻和降压两种方法。3三相交流异步电动机的制动方法有能耗制动、反接制动、反馈制动。4一台直流发电机，已知数据如下PN180KW，UN230V，NN1450RPM，N895，则该发电机的额定电流为A，额定转矩为NM。5三相异步电动机进行星三角降压起动时，起动电流为直接起动时的倍，起动转矩为直接起动时的倍。四、简答（每小题5分，共15分）1简述直流电动机不能直接启动的原因。答1换向器、电机绕组；（2）生产机械；（3）电网影响。2常用速度反馈元件有哪些其输出与转速的关系答常用速度反馈元件有测速发电机、光电编码器。测速发电机一般输出为直流电压，电压幅值与转速呈线性关系。光电编码器输出为频率可变的脉冲，其频率值与转速呈线性关系。五、计算设计题（55分）1一台直流他励电动机的技术数据为PN75KW，UN220V，IN35A,NN1500R/MIN，RA025，计算出此电动机的如下特性1固有机械特性；2电枢附加电阻分别为3和5时的人为机械特性；3电枢电压为UN/2时的人为机械特性；4磁通08N时的人为机械特性。（25分）解（1）根据公式（22035025）15000141NAENRIUK95501411345NENT59K根据固有机械特性方程2200141025（01411345）TTKN2NTEANE15601318T（2）电枢附加电阻分别为3和5时的人为机械特性1560（0253）（01411345）T156031TTKRUN2NTEADNE1560（0255）（01411345）T1560277T2TEADE3电枢电压为UN/2时的人为机械特性156021318T7801318TTKRN2TEAE4磁通08N时的人为机械特性1560081318064T19502059T640802NTEAE2直流他励电动机的数据PN55KW，UN220V，IN280A,NN635R/MIN，RA0044，带额定负载转矩运行，求1如果要求静差率S20，采用电枢回路串电阻调速和降压调速时所能达到的调速范围；2如果要求调速范围D4,采用以上两种调速方法时的最大静差率。（15分）解（1）求调速范围电枢回路串电阻调速时，额定负载转矩时容许的转速降为20/N0NS200267281346R/MIN/NN0容许的最低转速为NMINN0672813465382R/MIN，则调速范围为降压调速时，额定负载转矩下的转速降378R/MIN容许的最低理想空载转速为容许的最低转速为则调速范围为2调速范围D4时的最大静差率电枢回路串电阻调速时，容许的最低转速为最低转速时的转速降为则最大静差率为降压调速时，容许的最低转速为最低转速时的理想空载转速为则最大静差率为3启动时间。（15分）解（1）3一直流他励电动机，其额定功率PN40KW，额定电压UN220V，额定电流IN2033A，额定转速NN1500R/MIN，电枢绕组电阻RA006，系统的飞轮惯量GD215NM2，负载转矩TL是额定电磁转矩TN的06倍。若在电动机额定电流的二倍的条件下启动，试求1应串入电枢回路的电阻RAD；2启动过程中的IAT、NT；/NMAXNINI635D182/N/N0789RIS/MIN13512R/MINAXNINI6D452MAXNIN63518R/MIND4/N0IN728724/0S106N68MAXIN35R/IND4/0INN187196/MI/03S02TNENK9513272E0084启动瞬间电枢回路总电阻为NADSTUR51I305416082启动过渡过程的时间常数为电流初值为IST2IN220334066A额定电磁转矩为负载转矩为TL06TN06270162NM电枢稳态电流为理想空载转速为设最终稳态转速为NS，则由得于是可得3启动所需时间取4，则2M2ETGDR150418S375K37TI27NMT16IAK327N0EU058R/IN90SSTTLII0TL13461208R/MINIMMT/T/T/ALSTITE20E1245EM/T/N181T408472S请您删除一下内容，O_O谢谢2015年中央电大期末复习考试小抄大全，电大期末考试必备小抄，电大考试必过小抄AFTEREARNINGHISSPURSINTHEKITCHENSOFTHEWESTIN,THESHERATON,SENSONTHEBUND,ANDASPRINKLINGOFOTHERTOPNOTCHVENUES,SIMPSONLUFINALLYGOTTHECHANCETOBECOMEHISOWNBOSSINNOVEMBER2010SORTOFTHESHANGHAIBORNCHEFMIGHTNOTACTUALLYOWNCALIFORNIAPIZZAKITCHENCPKBUTHEISINSOLECHARGEOFBOTHKITCHENANDFRONTOFHOUSEATTHISSINANMANSIONSSTALWART“ITSCERTAINLYARESPONSIBILITYTOBETHEHEADCHEF,ANDTHENTOHAVETOMANAGETHERESTOFTHERESTAURANTASWELL,“THE31YEAROLDTELLSENJOYSHANGHAI“INHOTELS,FOREXAMPLE,THESEJOBSARESTRICTLYDEMARCATED,SOITSAGREATOPPORTUNITYTOLEARNHOWABUSINESSOPERATESACROSSTHEBOARD“ITWASATASKTHATMANAGEMENTBACKINSUNNYCALIFORNIAEVIDENTLYFELTHEWASREADYFOR,ANDAVOTEOFCONFIDENCEFROMACOMPANYTHAT,TODATE,HASOPENED250OUTLETSIN11COUNTRIESANDFORADDEDPRESSURE,THESHANGHAIBRANCHWASALSOCPKSCHINADEBUT“FORSUREITWASABIGSTEP,ANDUNLIKEALLTHEIROTHERASIAOPERATIONSTHATAREFRANCHISES,THEYDECIDEDTOMANAGEITDIRECTLYTOBEGINWITH,“SAYSSIMPSONTWOYEARSAGOAPRIVATEFRANCHISEETOOKOVERTHELEASE,BUTTHELINKSTOCPKHEADQUARTERSARESTILLSTRONG,WITHAMAINLANDBASEDBRANDAMBASSADORONHANDTOENSURETHEBUSINESSADHERESTOITSETHOSOFCREATING“INNOVATIVE,HEARTHBAKEDPIZZAS“,ASLICEOFPRBLURBTHATSIMPSONINSISTSLIVESUPTOTHEHYPE“THEYAREVERYINNOVATIVE,“HESAYS“THEPROBLEMWITHMOSTFASTFOODPLACESISTHATTHEYUSETHESAMESAUCEONEVERYPIZZAANDJUSTCHANGETHETOPPINGSEVERYONEOFOUR16PIZZASAUCESISAUNIQUERECIPETHATHASBEENFORMULATEDTOCOMPLEMENTTHETOPPINGSPERFECTLY“THELARGELYLOCALCUSTOMERBASEEVIDENTLYAGREESANDONSATURDAYANDSUNDAY,ATLEAST,THEPLACEISTEEMINGTHEKIDSEATFORFREEPOLICYATWEEKENDSISUNDOUBTEDLYABIGDRAW,ASWELLASISTHESPACIOUSSECONDFLOORLAYOUTOVERLOOKEDBYACANOPYOFGREENFROMFUXINGPARKOVERTHEROADTHECOMPANYISALSOFOCUSINGONINCREASINGBRANDRECOGNITIONANDINRECENTYEARSHASTAKENPARTINOUTSIDEEVENTSSUCHASTHEREGULARCALIFORNIAWEEKSTILL,THESTAAREHONESTENOUGHTOADMITTHATBUSINESSCOULDBEBETTERASGOOD,INFACT,ASINCPKSSECONDOUTLETINTHEPOPULARKERRYPARKSIDESHOPPINGMALLINPUDONG“SINANMANSIONSHASREALLYSTRUGGLEDTOGETTHENUMBEROFVISITORSTHATWEREENVISAGEDWHENITFIRSTOPENED,ANDITHASNTBEENEASYFORANYOFTHETENANTSHERE,“ADDSSIMPSON“WEREPLANNINGATHIRDOUTLETINTHECITYIN2015,ANDWEWILLPROBABLYCHOOSEASHOPPINGMALLAGAINBECAUSEOFTHEBETTERFOOTTRAFFIC“THETEAROOMSONCEFREQUENTEDBYCOCOCHANELANDMARCELPROUSTAREUPPINGSTICKSANDCOMINGTOSHANGHAI,XUJUNQIANVISITSTHEPARISIANOUTPOSTWITHSWEETTREATSONETHINGTHECENTURYOLDPARISIANTEAROOMANGELINAHASSHOWNISTHATLEGENDARYFASHIONDESIGNERCOCOCHANELNOTONLYHADSTYLEANDGLAMORBUTALSOBOASTEDGREATTASTEINFOOD,PASTRIESINPARTICULARONEOFTHEMOSTPOPULARTEAROOMSINPARIS,ANGELINAISFAMOUSFORHAVINGONCEBEENFREQUENTEDBYCELEBRITIESSUCHASCHANELANDWRITERMARCELPROUSTNOWANGELINAHASPACKEDUPITSFRENCHAMBIENCE,EFFICIENTSERVICE,ANDBEAUTIFUL,COMFORTINGDESSERTSANDFLOWNTHEMTOSHANGHAIATTHEFLAGSHIPDINEINANDTAKEOUTSPACEINSHANGHAI,E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