Seite - 247 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 616 Table1.ParametersofOW-PMSMdrivesystem. Items Parameters Motor type Interioropen-endwindingPMSM Numberofpolepairs p0 4 Stator resistanceRs/Ω 0.3 Equivalent iron loss resistanceRc/Ω 90 Fundamentalamplitudeandthirdharmonicamplitudeof permanentmagnetflux linkage[ψf ,ψf3]/Wb [0.2,0.01] d-axis inductanceLd/F 0.0012 q-axis inductanceLq/F 0.0015 Zerosequence inductanceL0/F 0.0003 Rotational inertiaof rotor Jm/kgm−2 0.011 Cullenresistancecoefficientandviscousresistancecoefficient [0.001,0.0005] DCbusvoltageofpowersource1Vdc1/V 240 DCbusvoltageofpowersource2Vdc2/V 230 Currentcapacityof inverterdevice imax/A 160 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 motor speed (r/min) 0 20 40 60 80 100 120 140 160 180 star mode triangle mode independent mode (with flux weakening) star mode independent mode triangle mode flux weakening region of independent mode Figure5.Externalcharacteristic curvesofeachwindingmode. Wecantell fromFigure5 that thespeedregulationrangeof trianglemode isabout √ 3 times that instarmodebut themaximumtorque is1/ √ 3 times that instarmode; thespeedregulationrange in thenon-flux-weakeningregion in independentmode isapproximately twice that instarmodeandits maximumtorque isequal to that instarmode. 2.2.WindingModesSwitchingStrategy Wefirstdeterminegeneralwindingmodes switching strategies. When themotor is in staror trianglemode,onlyone inverter isworkingwithon-state lossesandswitching losses.Whenanother inverterhas lowerbridgearmson, there isonlyon-state loss. In trianglemode, it isdifferent than when the triangle circuit switch is turnedon; there are on-state losses on triangle circuit. What is more, the topologyofstatorwinding in trianglemodedeterminesprobablezero-sequencecurrent in themotor,whichmaycontribute towastageof the inverter’scurrentcapacityandlossesonelectric resistanceandelectronicdevicesdueto thecurrent’sheatingeffect. In independentmode,bothsides’ invertersareworkingandhaveon-state lossesandswitchinglosses. Inconclusion, intermsof losses in electronicdevices, starmodehas the leastandindependentmodehas themost,with trianglemode in themiddle. Inorder toreduce those losses inelectronicdevices, thegeneralwindingmodesswitching strategymightbe that ifworkingconditionsareappropriate, starmode is thefirst choice, thentriangle mode; trynot touse independentmode. 247