Page - 33 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 1217 5.8.AxialFlux IronlessPermanentMagnetMotor Accordingto [70], thismotor is themostadvancedonetobeused inEVs. Ithasanouter rotor withnoslot; useof iron is avoidedhereaswell. Thestator core is absent too, reducing theweight of themachine. Theairgaphere is radialfield type,providingbetterpowerdensity. Thismotor is avariablespeedonetoo.Onenoteworthyadvantageof thismachine is that therotorscanbefitted onlateral sidesofwheels,placingthestatorwindingsontheaxlecentrally. Theslot-lessdesignalso improves theefficiencybyminimizingcopper lossas there ismorespaceavailable [70]. Powercomparisonof threedifferentmotor types is conducted inTable15. Table16compares torquedensitiesof threemotors. Table17summarizes theadvantagesanddisadvantagesofdifferent motor types,andshowssomevehiclesusingdifferentmotor technologies. Table15.Powercomparisonofdifferentmotorshavingthesamesize.Data from[72]. MotorType Power (kW) BaseSpeed MaximumSpeed HEV BEV IM 57 93 3000 12,000 SRM 42 77 2000 12,000 BLDC 75 110 4000 9000 Table16.Typical torquedensityvaluesofsomemotors.Data from[30]. MotorType Torque/Volume(Nm/m3) Torque/CuMass (Nm/kgCu) PMmotor 28,860 28.7–48 IM 4170 6.6 SRM 6780 6.1 Table17.Advantages,disadvantagesandusageofdifferentmotor types. MotorType Advantage Disadvantage VehiclesUsedIn BrushedDCMotor • Maximumtorqueat lowspeed • Bulkystructure • Lowefficiency • Heatgeneration atbrushes FiatPandaElettra (Series DCmotor),Conceptor G-Van(Separately excitedDCmotor) PermanentMagnet BrushlessDCMotor (BLDC) • Norotorcopper loss • Moreefficiency than inductionmotors • Lighter • Smaller • Betterheatdissipation • Morereliability • Moretorquedensity • Morespecificpower • Shortconstant powerrange • Decreasedtorque with increase inspeed • Highcostbecause ofPM ToyotaPrius (2005) PermanentMagnet SynchronousMotor (PMSM) • Operable indifferentspeedranges withoutusinggearsystems • Efficient • Compact • Suitable for in-wheelapplication • Hightorqueevenatvery lowspeeds • Hugeiron lossat highspeedsduring in-wheeloperation ToyotaPrius,Nissan Leaf,SoulEV InductionMotor (IM) • Themostmaturecommutatorless motordrivesystem • Canbeoperated likeaseparately excitedDCmotorbyemployingfield orientationcontrol TeslaModelS,Tesla ModelX,ToyotaRAV4, GMEV1 33