Page - 261 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 616 0 5 10 15 20 25 30 35 40 ш0.85 0.8ν0.85 0.7ν0.8 0.5ν0.7 <0.5 Average efficiency Proposed drive system Contrast drive system Figure13.Averageefficiencydistributionof fourdrivingcycles. It is evident that theproportionofhigh-efficiencyworkingpointsof theproposeddrivesystemis larger thanthatof thecontrastingsystem, thus thepowerconsumption isonaverage6.75%lower than thatof thecontrastingsystem. 5.Conclusions Thispaper, aimedatanelectricvehicle equippedwithanOW-PMSMdrive systemwithdual power sourcesanddual inverters; basedonanalyzing theexternal characteristicsof eachwinding mode,weproducedawindingmodeswitchingstrategywhosetorquesaturationjudgmentalalgorithm, insensitive to a motor’s parameters, could automatically realize upswitching of winding mode. Theproposedmulti-level currenthysteresismodulationalgorithmcanset themajorpowersourceand switch itatanytime in independentmode,accomplishingenergydistributionbetweentwopower sources; its twocontrolmethods, the lowswitchingfrequencymethodandthehighpowerdifference method,couldachievedifferentenergydistributioneffects. Fromthesimulationresults, compared withanOW-PMSMdrivesystemwith traditional two-levelcurrenthysteresismodulation,under the sameconditions theproposedsystemhas30%lower torquerippleanda lowerswitchingfrequencyof inverterdevices. Thus theproposedsystemhas3%higherpeakefficiencyanda largerhigh-efficiency area thanatraditionalOW-PMSMsystem.Byapplying it toelectricvehicles, thepowerconsumption is6.75%loweronaverageunder theproposedcontrolmethods.Moreover, throughits twodifferent controlmethods in independentmode, energydistributionbetween the twopowersources canbe realized, thus theDC/DCconverterbetweenthemcanbecancelled. Finally, the proposed winding mode switching strategy and multi-level current hysteresis modulationmethod take full advantage of eachwindingmode’sworking range, reduce inverter switching loss, increasesystemefficiency,andrealizeenergydistributionbetweentwopowersources. Itprovidesa theoreticalbasisandimplementationschemeafordual-powerOW-PMSMdrivesystem inelectricvehicles. Futureresearchwillbedirectedtowardsfindinganenergydistributionmethod matchedwith this systemforelectricvehicles tomaximize theoverall efficiencyanddrivingrange. Aftersolvingtheexistingpractical issues,anexperimentalverificationof theproposedsystemwill alsobeconducted inanelectricvehicle. Acknowledgments: Thisworkwas supportedby theChinaPostdoctoral ScienceFoundation (2014M561290), theEnergyAdministrationof JilinProvince [2016]35,andthe JilinProvinceScienceandTechnologyDevelopment Fund(20150520115JH). AuthorContributions:NanXuandLiangChuconceivedthecontrolmethodandrevised the fullmanuscript; Yi-fan JiaandDong-shengChenperformedthesimulationandwrote the fullmanuscript;Yan-weiWangand XinTanganalyzedthedata;ZheXuanalyzedandevaluatedthesimulationresultsandgavevaluablesuggestions. Conflictsof Interest:Theauthorsdeclarenoconflictof interest. 261