資源描述：
《電氣類畢業(yè)設(shè)計(jì)外文翻譯4》由會(huì)員上傳分享，免費(fèi)在線閱讀，更多相關(guān)內(nèi)容在學(xué)術(shù)論文-天天文庫。
1、畢業(yè)設(shè)計(jì)（論文）附錄A：英文參考文獻(xiàn)及其翻譯DirecttorquecontrolDirecttorquecontrol(DTC)isonemethodusedinvariablefrequencydrivestocontrolthetorque(andthusfinallythespeed)ofthree-phaseACelectricmotors.Thisinvolvescalculatinganestimateofthemotor'smagneticfluxandtorquebasedonthemeasuredvoltageandcurrentofthe
2、motor.MethodStatorfluxlinkageisestimatedbyintegratingthestatorvoltages.Torqueisestimatedasacrossproductofestimatedstatorfluxlinkagevectorandmeasuredmotorcurrentvector.Theestimatedfluxmagnitudeandtorquearethencomparedwiththeirreferencevalues.Ifeithertheestimatedfluxortorquedeviatesfr
3、omthereferencemorethanallowedtolerance,thetransistorsofthevariablefrequencydriveareturnedoffandoninsuchawaythatthefluxandtorquewillreturnintheirtolerancebandsasfastaspossible.Thusdirecttorquecontrolisoneformofthehysteresisorbang-bangcontrol.Thiscontrolmethodimpliesthefollowingproper
4、tiesofthecontrol:·Torqueandfluxcanbechangedveryfastbychangingthereferences·Highefficiency&lowlosses-switchinglossesareminimizedbecausethetransistorsareswitchedonlywhenitisneededtokeeptorqueandfluxwithintheirhysteresisbands·Thestepresponsehasnoovershoot·Nocoordinatetransformsareneede
5、d,allcalculationsaredoneinstationarycoordinatesystem·Noseparatemodulatorisneeded,thehysteresiscontroldefinestheswitchcontrolsignalsdirectly·TherearenoPIcurrentcontrollers.Thusnotuningofthecontrolisrequired·Theswitchingfrequencyofthetransistorsisnotconstant.However,bycontrollingthewi
6、dthofthetolerancebandstheaverageswitchingfrequencycanbekeptroughlyatitsreferencevalue.Thisalsokeepsthecurrentandtorqueripplesmall.Thusthetorqueandcurrentrippleareofthesamemagnitudethanwithvectorcontrolleddriveswiththesameswitchingfrequency.·Duetothehysteresiscontroltheswitchingproce
7、ssisrandombynature.Thustherearenopeaksinthecurrentspectrum.Thisfurthermeansthattheaudiblenoiseofthemachineislow·TheintermediateDCcircuit'svoltagevariationisautomaticallytakenintoaccountinthealgorithm(involtageintegration).Thusnoproblemsexistduetodcvoltageripple(aliasing)ordcvoltaget
8、ransients·Synchroni
