电气类毕业设计外文翻译4

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1、毕业设计（论文）附录A：英文参考文献及其翻译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