electromagnetic-thermal integration design of permanent

Research ArticleElectromagnetic-Thermal Integration Design ofPermanent Magnet Motor for Vehicles

Shijun Chen 12 Qi Zhang 1 and Surong Huang1

1School of Mechatronic Engineering and Automation Shanghai University Shanghai 200072 China2School of Physics and Electronic Engineering Anqing Normal University Anqing 246133 China

Correspondence should be addressed to Qi Zhang qizhangstaffshueducn

Received 13 December 2018 Accepted 28 March 2019 Published 2 May 2019

Academic Editor M Tariq Iqbal

Copyright copy 2019 Shijun Chen et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

To more efficiently design high performance vehicular permanent magnet motor an electromagnetic-thermal integration designmethod is presented which considers both the electromagnetic properties and the temperature rise of motor winding whendetermining the main dimensional parameters of the motor Then a 48-slot and 8-pole vehicular permanent magnet motor isdesigned with this methodThe thermomagnetic coupling design is simulated and validated on the basis of multiphysical domainon finite element analysis Then the prototype is analyzed and tested on a newly built motor experiment platform It is shown thatthe simulation results and experimental results are consistent which validate the accuracy and effectiveness of the new designmethod Also this method is proved to well improve the efficiency of permanent magnet motor design

1 Introduction

Vehicular permanent magnet motors are outstanding withhigh torquecurrent high power density high efficiency andminitype light-weight The urgent problems of motor designare how to reduce motor volume save space and improvematerial utilization rate while meeting specific performanceindices The design aims of vehicular permanent magnetmotor should be high density low weight high reliabilityhigh power at low-velocity and constant-power wide-rangespeed control and to utmost increase themotor power densitywithin limited space by enlarging the electromagnetic loadThus the size limit electromagnetic load and thermal load ofvehicularmotor are all far larger than commonmotor and thetemperature rise of motor becomes an extremely importantindicator during vehicular permanent magnet motor design[1ndash3]The traditional designmethods of vehicular permanentmagnet motor are to firstly design an electromagnetismscheme and thereby simulate temperature rise the schemeis redesigned if the temperature rise is too high This wayis repeated until the electromagnetism scheme and motortemperature rise both are qualified Admittedly such designmethods largely enlarge the workload of engineers and are

less efficient Thus the electromagnetism design of vehicularpermanent magnet motor should be integrated with the ther-mal design forming an electromagnetic-thermal integrationdesign (ETID) theoretical method for vehicular permanentmagnet motor

Currently several methods for thermal analysis havebeen investigated in the literature As reported with afluid-structure interaction finite element method (FEM)the steady-state temperature field of a 42 kW water-cooledvehicular permanentmagnet synchronousmotor under ratedoperating condition was simulated and analyzed [4] Aspecial cooling system and a new rotor structure prototypeFEM model were built and were divided according to theheat production rate inside the motor andmaterial properties[5] A thermal magnetic coupling method for axial magneticflux permanent magnet motor was proposed and used to seg-ment the stators and rotors by using convection conductionanalytical equations [6] The thermal magnetic coupling ofa double-salient-pole and double-rotor permanent magnetmotor was analyzed by integrating thermal networks andFEM [7] The lumped-parameter thermal network methodand 3D fluid analysis were combined when the thermaleffects of a surface-mounted permanent magnet motor with

HindawiInternational Journal of Rotating MachineryVolume 2019 Article ID 9653231 8 pageshttpsdoiorg10115520199653231

2 International Journal of Rotating Machinery

overhang structure were considered [8] An electromagnetic-thermal-fluid integration analyticalmethodwas proposed fora permanent magnet synchronousmotor [9] A finite elementpackage was used for the transient thermal analysis underdifferent load conditions and ambient temperatures of asurface-mounted permanent magnet synchronous motor foraerospace actuation applications [10]The thermal simulationmodel of in-wheel motor used for solar car was establishedthe thermal characteristics of in-wheel motor were analyzedby building the mass flow and heat-transfer coupling simula-tion model [11] A new electrical-thermal two-way couplingdesign method was proposed to analyze the electromagneticperformances based on the investigated FSPM motor wherethe change of PM material characteristics under differenttemperatures was taken into consideration [12] A new Axial-Radial Flux-Type Permanent Magnet Synchronous Motorwas presented The performance of Axial-Radial Flux-TypePermanent Magnet Synchronous Motor (ARFTPMSM) canbe adjusted by changing Axial Magnetic Motive Force(AMMF) The three-dimensional steady-state temperaturefield distributions of ARFTPMSM under different AMMFwere investigated by using time-stepping FEM [13]

Simultaneously several methods of motor design alsohave been investigated in the literature The design processesin electromagnetic aspect of a high-speed solid cylindricalPM motor equipped with magnetic bearings were presented[14] The design of the 4-kW 150-krpm ultra-high-speedSPMSM for an electrically assisted turbocharger was pre-sented [15] A novel surface-mounted outer rotor transverseflux permanent magnet motor with simple structure andgood performance was proposed which improved the motorperformance by transforming parts of the leakage flux intothemain flux [16]The rotor shapes of IPMmotors for electricvehicles were analyzed and five types ofmotor rotors for auto-mobiles were analyzed including two hybrid vehicles [17]

The above studies suggest the existence of many practicaland feasible methods for motor thermal performance com-putation and electromagnetic design However the thermalperformance simulation in all methods is conducted afterthe motor electromagnetic scheme is determined and thereis rare research on ETID In this paper based on the basictheories of traditional motor electromagnetic design andthermal design we proposed an ETID method for motordesign The effectiveness and superiority of this method werevalidated by using a newly built 48-slot and 8-pole vehicularwater-cooled permanent magnet motor

2 Generalized Equations of ETID

21 Computation of Motor Main Dimensions When theelectromagnetic load effective core length or length-diameterratio armature-phase voltage and phase current waveformcoefficient magnetic field waveform coefficient and windingfactor are all constant the electromagnetic torque Tem of themotor is decided by the motor armature inner diameter andcan be computed as follows [18]

119879119890119898 = 12058711987011989411987011987311987211987011988911990111986321198941199041198971198901198911198601198611205752 (1)

Dos

Dts

Dis Dor

bsa

bts

ℎts ℎjs

Figure 1 Stator structure of permanent magnet motor for vehicle

whereKi is themotor phase currentwaveform coefficientKNM is the magnetic field waveform coefficient Kdp is thewinding factor Dis is the motor stator inner diameter lef isthe effective stator core length A is the line load and 119861120575 isthe peak value of air gap flux density

The stator structure of permanent magnet motor forvehicle is shown in Figure 1 where Dos is external diameterof motor stator Dts is stator tooth root diameter Dor isrotor diameter bts is stator tooth width bsav is the equivalentaverage slot width hjs is stator yoke height hts is tooth heightand equal to the equivalent average slot height hsav and 120575 isair gap thickness As seen in Figure 1

ℎ119905119904 = 119863119905119904 minus 1198631198941199042ℎ119895119904 = 119863119900119904 minus 1198631199051199042

(2)

The ratio of 119861120575 to the calculated diameter of stator teethflux density Bts and yoke flux density Bjs is respectively

119896119905119904 = 119861120575119861119905119904119896119895119904 = 119861120575119861119895119904

(3)

The total air gap flux of permanent magnet motor forvehicle is calculated as follows where 1205721015840119901 is the computationarc coefficient 119861120575119886V is average air gap flux density

Φ119905 = 12058712057210158401199011198631198941199041198971198901198911198611205751205721015840119901 = 119861120575119886V119861120575

(4)

The total tooth area and slot area at the calculated diam-eter of stator teeth of vehicle permanent magnet motor arecalculated as follows where kls is the core length coefficient

International Journal of Rotating Machinery 3

and usually is approximated to 1 Js is the stator windingcurrent density and Sf is the coil space factor

sum119904119905119904 = sum119887119905119904 lowast ℎ119905119904 = Φ119905ℎ119905119904119870119865119890119904119897119865119890119904119861119905119904= 1205871205721015840119901119896119905119904119863119894119904 (119863119905119904 minus 119863119894119904)2119870119865119890119904119896119897119904

sum119904119904119904 = 120587119863119894119904119860119869119904119878119891

(5)

Since the area between the root of stator teeth and theinner diameter of stator equals the sum of the total teeth andslot area of stator the following formula is obtained

sum119904119905119904 +sum119904119904119904 = 120587 (1198632119905119904 minus 1198632119894119904)4

= 1205871205721015840119901119896119905119904119863119894119904 (119863119905119904 minus 119863119894119904)2119870119865119890119904119896119897119904 + 120587119863119894119904119860119869119904119904119891(6)

The quadratic equation of stator inner diameter withrespect to stator outer diameter of vehicle permanent magnetmotor is obtained

1198601199001199041198941199041198632119900119904 minus 2119861119900119904119894119904119863119900119904 + 119862119900119904119894119904 = 0 (7)

Solution

119863119894119904 = 119891 (119863119900119904) = 119861119900119904119894119904 plusmn radic119861119900119904119894119904 2 minus 119860119900119904119894119904119862119900119904119894119904119860119900119904119894119904 (8)

where

119860119900119904119894119904 = 12058721205722119901 11989621198951199044119901211987021198651198901199041198962119897119904 +1205722119901 11989611989511990411989611990511990411990111987021198651198901199041198962119897119904 +

2120572119901119896119905119904119870119865119890119904119896119897119904 minus 1119861119900119904119894119904 = (119896119905119904 + 1205871198961198951199042119901 )

120572119901119870119865119890119904119896119897119904119863119874119878 +2119860119869119904119878119891

119862119900119904119894119904 = 1198632119900119904

(9)

where kjs is the ratio of peak flux density in air gap to the fluxdensity at stator yoke kts is the ratio of the flux density in airgap to the flux density in the stator tooth KFes is the corestacking coefficient p is the number of pole pairs Js is thestator winding current density and Sf is the coil space factor

The stator tooth width bts can be computed as follows

119887119905119904 = 1205871205721015840119901119896119905119904119863119894119904119885119904119870119865119890119904119896119897119904 (10)

where Zs is the stator slot number

22 Computation of Temperature Rise in Stator SlotsDuringmotor designing generally the winding heat is the mostnondissipatable and usually the temperature rise of all other

parts can be satisfactory as long as the temperature rise ofwinding is qualified

The stator slot was divided into 4 zones of winding slotwedge insulating paper and slot wall gapsThe impregnatingvarnish and fine air gap inside the slots were successivelyand evenly assigned to the outer layer of each varnished wirecomposed of bare copper wire and varnish film In otherwords one bare copper wire wire varnish film layer cylin-drical walls impregnating varnish layer cylindrical wallsand fine air gap cylindrical walls together constituted anequivalent conductor and the N equivalent conductors ineach slot constituted a winding Regarding the winding asa heat source its equivalent thermal conductivity coefficientwas calculated as follows [19]

120582119904119890 = 111205820 + 2sum119899119894=1 (1120582119894) ln (119877119894119877119894minus1) (11)

where 120582se is the equivalent thermal conductivity coefficientinside the stator slot R0 and 1205820 are the radius and thermalconductivity coefficient of bare copper wire respectively Rnis the radius of the outmost circle Ri and 120582i are the radiusand thermal conductivity coefficient of inner walls in the i-thlayer in the middle respectively here n=3 R1 R2 and R3 arethe radii of the varnish film layer the impregnating varnishlayer and the fine air gap layer respectively R1 R2 and R3can be calculated as follows [19]

1198771 = 1198770 + 1198891199081198772 = 119870119871 (1198773 minus 1198771) + 11987711198773 = radic119860119886119903119890119886 minus 119862119904119900119897119905 (120575119886 + 119889119894119899)119873120587

(12)

where 120575119886 is the thickness of slot wall gaps din is the thicknessof insulation paper KL is the varnish filling coefficient Aareaand Cslot are the slot area and slot perimeter except the slotwedge respectively and both are decided by the average slotlength hsav and the average slot width bsav After substitutinginto (11) the equivalent thermal conductivity inside the statorslot can be calculated

The stator slot thermal resistance consists of radialcircumferential and axial parts of thermal resistance Sincethe copper loss mainly conducts from inner to outer hereonly the temperature rise of radial thermal resistance wasconsidered The thermal resistance Rth all inside a slot can becalculated as follows [20]

119877119905ℎ 119886119897119897 = (ℎ119904119886V minus 2119889119894119899 minus 2120575119886) 2120582119904119890119897119890119891 (119887119904119886V minus 2119889119894119899 minus 2120575119886)+ 119889119894119899120582119894119899119897119890119891 (119887119904119886V minus 2120575119886) +

120575119886120582119886119897119890119891119887119904119886V(13)

where 120582in is the thermal conductivity coefficient of insulationpaper 120582a is the thermal conductivity coefficient of air Thusthe temperature rise inside each slot can be calculated asfollows

Δ120579119908 = 119875119888119906119885119904 times 119877119905ℎ 119886119897119897 (14)


Start

Initial determination of pole-slot match stator diameter and length of core

Preliminary estimation of motor flux density based on speed

Motor model is established afterrefined adjustment of motor sizes

End

Yes

No

No

Output motor calculation results

Finite element method simulation calculation

Winding Temperature rise is calculated from Eqs (14)

Judge whether torque efficiency and otherperformance requirements are met

Yes

Stator inner diameter DＣＭ is computed from Eqs (8)

Tooth width bＮＭ is computed from Eqs (10)

Adjust motor sizes

permanent magnetdimensions

DＣＭ bＮＭ ℎＭ and rotorΔw le 09(Tℎ minus Ta)

Figure 2 Electromagnetic-thermal integration design process

where Pcu is copper loss and can be empirically calculatedaccording to themotor efficiency requirements and engineer-ing design Clearly under the same copper loss when the coilspace factor slot insulation thickness thermal conductivitycoefficients of slot insulation impregnating varnish andvarnish films and varnish filling coefficient are all constantthe temperature rise of the stator slot is directly proportionalto the slot equivalent height hsav but is inversely proportionalto the slot equivalent width bsav and the stator core lengthlef According to experience at the ambient temperatureTa gt 40∘C the permitted temperature rise of motor windingshould meet the following condition [21]

Δ120579119908 le 09 (119879ℎ minus 119879119886) (15)

where Th is the highest temperature and can be assignedwith different empirical values according to the grade ofinsulation (eg A B F H)

In sum the major dimensional parameters of a motornot only relate to its electromagnetic performance but alsocritically affect the temperature rise of motor winding

3 Key Technical Flow Chart of ETID

The key technical flowchart of the ETID is illustrated inFigure 2 Firstly according to the design requirements appro-priate pole-slot match is selected the motor stator outerdiameter and motor iron core length are determined theflux density is estimated according to the preset rotatingspeed the stator inner diameter and tooth breadth arecomputed from (8) and (10) after refined adjustment theshape of the stator slot is determined Secondly the motorwinding temperature rise is calculated and judged accordingto (14) and (15) if the requirements of temperature rise areunsatisfied themotor inner diameterDis tooth width bts and

International Journal of Rotating Machinery 5Te

mpe

ratu

re ri

se(∘

C)

＜ＭＰ (m)

300

250

200

150

100

50

0

0005 00055 0006 00065 0007 00075

ＢＭＰ=00080mＢＭＰ=00085mＢＭＰ=00090m

ＢＭＰ=00095mＢＭＰ=00100m

Figure 3The curves of temperature rise in stator slot versus bsav andhsav

0 1 2 3 4 5 6 7 8 9

No-

Load

line

bac

k-EM

F (V

)

200

160

120

80

40

0

minus40

minus80

minus120

minus160

minus200

Time (sec)times10minus3

Figure 4 No-Load line back-EMF simulation waveform at4000rmin

slot height hs should be adjusted until the conditions are sat-isfied Finally an appropriate rotor magnetic steel structure isselected and a complete motor model is established for FEMcomputation the electromagnetic torque efficiency andother performance indices of the motor are evaluated if thedesign requirements are unsatisfied the motor dimensionsincluding rotor structure should be adjusted or refined untilthe design requirements are met

4 ETID Simulation on FEM

According to the dimensional relation in Section 21 weset the outer diameter 230 mm as the baseline pole-slotmatch = 48-slot and 8-pole waveform coefficient KNm=111

Elec

trom

agne

tic to

rque

(Nm

)

0 05 1 15 2 25 3 35 4

213

2125

212

2115

211

2105

210

2095

209


Figure 5 Electromagnetic torque simulation waveform at4000rmin88kW

phase current waveform coefficient Ki= 1414 axial length lef=160mm and rated rotating speed n=4000 rpm and therebyapproximately estimated the electromagnetic density Thestator inner diameterDis can be preliminarily estimated from(8) At the core stacking coefficient KFes =097 and 119861120575 =06Twe calculated the stator tooth width from (10)

According to formulas (13) and (14) the curves oftemperature rise in stator slot versus the equivalent heightand width of stator slot are obtained as shown in Figure 3It can be seen that the temperature rise in the stator slotis proportional to the equivalent height of the stator slothsav and inversely proportional to the equivalent width ofthe slot bsav Considering that the insulation level of theprototype winding is H and the ambient temperature is 48∘Cthe maximum temperature rise of the motor is estimatedaccording to formula (15)

According to the above preliminary estimations wedesigned a V-shaped rotor structure appropriately refinedthe dimensional parameters and designed the prototypemachine with the performance and major dimensionsshowed in Table 1 The No-Load line back-EMF simulationwaveform at 4000 rmin is illustrated in Figure 4 withthe peak at 318 V The electromagnetic torque simulationwaveform at 4000rmin88kW is showed in Figure 5 withthe average electromagnetic torque 2107 N∙m

Given the multiphysical domain of circuit electromag-netism fluid and temperature and based on the couplingsimulation of control circuit electromagnetic calculationand thermal analysis we determined the temperature dis-tributions of key motor parts of the vehicular permanentmagnet motor at working condition 4000rmin42kW andconsidering inverter harmonic loss (Figure 6[3])The highesttemperatures of water jacket statorwinding stator core rotorcore and permanent magnet were 495∘C 1138∘C 1148∘C1222∘C and 1224∘C respectively

5 Experimental Verification

The test platform for prototype machine has been set up asshown in Figure 7 in which two identical motors with the


TemperatureContour 1

[K]

3226e+002

3224e+002

3223e+002

3221e+002

3220e+002

3219e+002

3217e+002

3216e+002

3214e+002

3213e+002

3211e+002

(a)


[K]

3870e+002

3857e+002

3845e+002

3833e+002

3821e+002

3809e+002

3796e+002

3784e+002

3772e+002

3760e+002

3747e+002

(b)


[K]

3954e+002

3911e+002

3869e+002

3826e+002

3784e+002

3741e+002

3699e+002

3656e+002

3614e+002

3572e+002

3529e+002

(c)


[K]

3956e+002

3944e+002

3931e+002

3919e+002

3907e+002

3894e+002

3882e+002

3870e+002

3857e+002

3845e+002

3833e+002

(d)

Figure 6 Temperature distribution after considering the harmonic loss (a) water jacket (b) stator winding (c) stator and rotor core (d)magnet

rated power 42kW are driven with each other The testedmotor adopts torque control while the othermotor uses speedcontrol In addition the cooling system is used in this experi-ment With the purpose of monitoring temperature variationin each component thermal resistors are respectively placedat the end winding of motor the outer wall of frame theunderside of rotor permanent magnet the water inlet andthe outlet of frameThe inlet water temperature is set for 48∘Cwith the water flow rate 12Lmin

The No-Load line back-EMF measured waveform at4000rminwas showed in Figure 8 with the peak value at 322V Clearly the experimental data are very consistent with thesimulation results in terms of waveform amplitude and shape

The current waveform experimentally measured at4000rmin88kW was showed in Figure 9 Since a current

amplifier was used in the experiments what the oscilloscopedisplayed was voltage signals The voltage peak value was1064 V and the current voltage change ratio was 1 AmVAfter conversion the peak current of the input motor was1064 A or namely the current amplitude was 532 A thecurrent advance angle 37∘ and motor output torque 2106NmThe experimental results are very close to the simulationresults

The stator winding temperature and permanent magnettemperature measured at 4000rmin42kW were 112∘C and123∘C respectively which were very close to the simulatedresults (1138∘C 1224∘C)

In all the electromagnetic simulation results and thermalsimulation results were very close to the experimentallymeasured results indicating the vehicular permanent magnet


TemperatureSensor Signal

Figure 7 Test platform for prototype machine

Figure 8 No-Load line back-EMF measured waveform at4000rmin

motor ETID method proposed here was accurate and effec-tive

6 Conclusions

An efficient vehicular permanent magnet motor ETIDmethod was proposed which integrated both electromag-netism design and temperature rise design and therebylargely shortened the motor schematic designing period andenhanced the efficiency(1)Duringmotor design the key dimensional parametersaffecting motor electromagnetic performance included statorinner diameter and tooth width equations of which werepresented here(2) Temperature rise of motor stator winding was a keyindicator of motor thermal performance Here the intraslotwinding thermal conductive coefficient was equivalentlycomputed and thereby the winding temperature rise wasestimated Togetherwith the empirical value range of windingtemperature rise the thermal design of motor winding wasconducted which was highly practical(3) A 48-slot and 8-pole permanent magnet motor withthe rated power 42 KWwas built for ETIDThe experimentaldatawere consistentwith the simulated dataThemotor ETID

Figure 9 Measured waveform of input current at 4000rmin88kW

Table 1 Performance and main dimensions of prototype machine

Parameters ValueRated power (kW) 42Rated speed (rpm) 4000Maximum power (kW) 88Maximum speed (rpm) 11500Stator outer diameter Dos (mm) 230Stator inner diameter Dis (mm) 1564Rotor inner diameter (mm) 43Poleslot 848Core length (mm) 160Stator slot height hs (mm) 20Tooth width bts (mm) 654Air-gap length (mm) 06Winding insulation level H

method was proved effective accurate and excellent and pro-vides effective means for practical engineering applications

Data Availability

The nature of the data is the motor size parameters thedata can be accessed from Electrical Machinery Laboratoryof Shanghai University The complete data belong to thejoint ownership of the Electrical Machinery Laboratory ofShanghai University and the enterprise

Conflicts of Interest

The authors declare no conflicts of interest

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China under Grant no 61572238 and theShanghai Industry-University-Institute Cooperation AnnualPlan Project under Grant no Hu CXY-2015-014


References

[1] T D Kefalas and A G Kladas ldquoThermal investigation of per-manent-magnet synchronous motor for aerospace applica-tionsrdquo IEEE Transactions on Industrial Electronics vol 61 no8 pp 4404ndash4411 2014

[2] H Xuzhen L Jiaxi Z Chengming and L Liyi ldquoCalculationand experimental study on temperature rise of a high overloadtubular permanent magnet linear motorrdquo IEEE Transactions onPlasma Sciences vol 41 no 5 pp 1182ndash1187 2013

[3] S J Chen Q Zhang B He S R Huang and D-D Hui ldquoTher-mal analysis of high density permanent magnet synchronousmotor based on multi physical domain coupling simulationrdquoJournal of Electrical Engineering amp Technology vol 12 no 1 pp91ndash99 2017

[4] Z Qi W Weixu H Surong and G Jianwen ldquoHeat tansfersimulation of high density permanent magnet motor for vehi-cles based on fluid-solid coupling methodrdquo ElectricMachines ampControl Application vol 8 pp 86ndash90 2012

[5] AM El-Refaie J P Alexander S Galioto et al ldquoAdvanced highpower-density interior permanent magnet motor for tractionapplicationsrdquo in Proceedings of the 2013 IEEE Energy ConversionCongress and Exposition pp 581ndash590 IEEE USA September2013

[6] H Vansompel A Rasekh A Hemeida J Vierendeels and PSergeant ldquoCoupled electromagnetic and thermal analysis of anaxial flux PMmachinerdquo IEEETransactions onMagnetics vol 51no 11 Article ID 8108104 2015

[7] Y Chen X Zhu L Quan and L Wang ldquoPerformance analysisof a double-salient permanent-magnet double-rotor motorusing electromagnetic-thermal coupling methodrdquo IEEE Trans-actions on Applied Superconductivity vol 26 no 4 Article ID5205305 2016

[8] H K Yeo H J Park J M Seo S Y Jung J S Ro and HK Jung ldquoElectromagnetic and thermal analysis of a surface-mounted permanentmagnet motor with overhang structurerdquoIEEE Transactions on Magnetics vol 53 no 6 Article ID8203304 2017

[9] Y Jiang D Wang J Chen Q Zhang and T Xuan ldquoElectro-magnetic-thermal-fluidic analysis of permanent magnet syn-chronousmachine by bidirectional methodrdquo IEEE Transactionson Magnetics vol 54 no 3 Article ID 8102705 2018

[10] TD Kefalas andAGKladas ldquoFinite element transient thermalanalysis of PMSM for aerospace applicationsrdquo in Proceedings ofthe 2012 20th International Conference on Electrical MachinesICEM 2012 pp 2566ndash2572 France September 2012

[11] F-X Yao Z-K Zhang and Y-T Zhang ldquoSimulation researcheson thermal characteristics of vehicular in-wheel motorsrdquo inProceedings of the 3rd 2017 International Conference on Sustain-able Development (ICSD 2017) pp 329ndash335 Tianjin China July2017

[12] Z Shu X Zhu L Quan Y Du and C Liu ldquoElectromagneticperformance evaluation of an outer-rotor flux-switching per-manent magnet motor based on electrical-thermal two-waycoupling methodrdquo Energies vol 10 no 5 article 677 2017

[13] D Li Y Wen W Li B Feng and J Cao ldquoThree-dimensionaltemperature field calculation and analysis of an axial-radialflux-type permanentmagnet synchronousmotorrdquo Energies vol11 no 5 article 1208 2018

[14] S Xu X Liu and Y Le ldquoElectromagnetic design of a high-speed solid cylindrical permanent-magnet motor equipped

with activemagnetic bearingsrdquo IEEETransactions onMagneticsvol 53 no 8 Article ID 8203715 2017

[15] M-S Lim J-M Kim Y-S Hwang and J-P Hong ldquoDesignof an ultra-high-speed permanent-magnet motor for an elec-tric turbocharger considering speed response characteristicsrdquoIEEEASME Transactions on Mechatronics vol 22 no 2 pp774ndash784 2017

[16] D Xianming ldquoDesign and performance analysis of a noveltransverse flux permanent-magnet motorrdquo International Jour-nal of Applied Electromagnetics amp Mechanics vol 56 pp 623ndash635 2018

[17] M-H Hwang J-H Han D-H Kim and H-R Cha ldquoDesignand analysis of rotor shapes for IPM motors in EV powertraction platformsrdquo Energies vol 11 no 10 article 2601 2018

[18] Z Xiang Electric ExcitationPM BSG Synchronous Motor inVehicle Design Theory and Simulation Comparison ShanghaiUniversity Shanghai China 2016

[19] ZQi L XiruiH Surong andZ Jun ldquoTemperature rise calcula-tions of high density permanentmagnetmotors based onmulti-domain co-simulationrdquo Proceedings of the CSEE vol 34 no 12pp 1874ndash1881 2014

[20] G Huang and F Fu Small And Medium Sized Rotary MotorDesign Manual China Electric Power Press 2014

[21] E Levi Polyphase Motors chap10 Wiley 1986

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overhang structure were considered [8] An electromagnetic-thermal-fluid integration analyticalmethodwas proposed fora permanent magnet synchronousmotor [9] A finite elementpackage was used for the transient thermal analysis underdifferent load conditions and ambient temperatures of asurface-mounted permanent magnet synchronous motor foraerospace actuation applications [10]The thermal simulationmodel of in-wheel motor used for solar car was establishedthe thermal characteristics of in-wheel motor were analyzedby building the mass flow and heat-transfer coupling simula-tion model [11] A new electrical-thermal two-way couplingdesign method was proposed to analyze the electromagneticperformances based on the investigated FSPM motor wherethe change of PM material characteristics under differenttemperatures was taken into consideration [12] A new Axial-Radial Flux-Type Permanent Magnet Synchronous Motorwas presented The performance of Axial-Radial Flux-TypePermanent Magnet Synchronous Motor (ARFTPMSM) canbe adjusted by changing Axial Magnetic Motive Force(AMMF) The three-dimensional steady-state temperaturefield distributions of ARFTPMSM under different AMMFwere investigated by using time-stepping FEM [13]

Simultaneously several methods of motor design alsohave been investigated in the literature The design processesin electromagnetic aspect of a high-speed solid cylindricalPM motor equipped with magnetic bearings were presented[14] The design of the 4-kW 150-krpm ultra-high-speedSPMSM for an electrically assisted turbocharger was pre-sented [15] A novel surface-mounted outer rotor transverseflux permanent magnet motor with simple structure andgood performance was proposed which improved the motorperformance by transforming parts of the leakage flux intothemain flux [16]The rotor shapes of IPMmotors for electricvehicles were analyzed and five types ofmotor rotors for auto-mobiles were analyzed including two hybrid vehicles [17]

The above studies suggest the existence of many practicaland feasible methods for motor thermal performance com-putation and electromagnetic design However the thermalperformance simulation in all methods is conducted afterthe motor electromagnetic scheme is determined and thereis rare research on ETID In this paper based on the basictheories of traditional motor electromagnetic design andthermal design we proposed an ETID method for motordesign The effectiveness and superiority of this method werevalidated by using a newly built 48-slot and 8-pole vehicularwater-cooled permanent magnet motor

2 Generalized Equations of ETID

21 Computation of Motor Main Dimensions When theelectromagnetic load effective core length or length-diameterratio armature-phase voltage and phase current waveformcoefficient magnetic field waveform coefficient and windingfactor are all constant the electromagnetic torque Tem of themotor is decided by the motor armature inner diameter andcan be computed as follows [18]

119879119890119898 = 12058711987011989411987011987311987211987011988911990111986321198941199041198971198901198911198601198611205752 (1)

Dos

Dts

Dis Dor

bsa

bts

ℎts ℎjs

Figure 1 Stator structure of permanent magnet motor for vehicle

whereKi is themotor phase currentwaveform coefficientKNM is the magnetic field waveform coefficient Kdp is thewinding factor Dis is the motor stator inner diameter lef isthe effective stator core length A is the line load and 119861120575 isthe peak value of air gap flux density

The stator structure of permanent magnet motor forvehicle is shown in Figure 1 where Dos is external diameterof motor stator Dts is stator tooth root diameter Dor isrotor diameter bts is stator tooth width bsav is the equivalentaverage slot width hjs is stator yoke height hts is tooth heightand equal to the equivalent average slot height hsav and 120575 isair gap thickness As seen in Figure 1

ℎ119905119904 = 119863119905119904 minus 1198631198941199042ℎ119895119904 = 119863119900119904 minus 1198631199051199042

(2)

The ratio of 119861120575 to the calculated diameter of stator teethflux density Bts and yoke flux density Bjs is respectively

119896119905119904 = 119861120575119861119905119904119896119895119904 = 119861120575119861119895119904

(3)

The total air gap flux of permanent magnet motor forvehicle is calculated as follows where 1205721015840119901 is the computationarc coefficient 119861120575119886V is average air gap flux density

Φ119905 = 12058712057210158401199011198631198941199041198971198901198911198611205751205721015840119901 = 119861120575119886V119861120575

(4)

The total tooth area and slot area at the calculated diam-eter of stator teeth of vehicle permanent magnet motor arecalculated as follows where kls is the core length coefficient




sum119904119904119904 = 120587119863119894119904119860119869119904119878119891

(5)


sum119904119905119904 +sum119904119904119904 = 120587 (1198632119905119904 minus 1198632119894119904)4

= 1205871205721015840119901119896119905119904119863119894119904 (119863119905119904 minus 119863119894119904)2119870119865119890119904119896119897119904 + 120587119863119894119904119860119869119904119904119891(6)


1198601199001199041198941199041198632119900119904 minus 2119861119900119904119894119904119863119900119904 + 119862119900119904119894119904 = 0 (7)

Solution


where

119860119900119904119894119904 = 12058721205722119901 11989621198951199044119901211987021198651198901199041198962119897119904 +1205722119901 11989611989511990411989611990511990411990111987021198651198901199041198962119897119904 +

2120572119901119896119905119904119870119865119890119904119896119897119904 minus 1119861119900119904119894119904 = (119896119905119904 + 1205871198961198951199042119901 )

120572119901119870119865119890119904119896119897119904119863119874119878 +2119860119869119904119878119891

119862119900119904119894119904 = 1198632119900119904

(9)



119887119905119904 = 1205871205721015840119901119896119905119904119863119894119904119885119904119870119865119890119904119896119897119904 (10)





120582119904119890 = 111205820 + 2sum119899119894=1 (1120582119894) ln (119877119894119877119894minus1) (11)



(12)




120575119886120582119886119897119890119891119887119904119886V(13)


Δ120579119908 = 119875119888119906119885119904 times 119877119905ℎ 119886119897119897 (14)


Start




End

Yes

No

No





Yes



Adjust motor sizes





Δ120579119908 le 09 (119879ℎ minus 119879119886) (15)






mpe

ratu

re ri

se(∘

C)

＜ＭＰ (m)

300

250

200

150

100

50

0

0005 00055 0006 00065 0007 00075




0 1 2 3 4 5 6 7 8 9

No-

Load

line

bac

k-EM

F (V

)

200

160

120

80

40

0

minus40

minus80

minus120

minus160

minus200






Elec

trom

agne

tic to

rque

(Nm

)

0 05 1 15 2 25 3 35 4

213

2125

212

2115

211

2105

210

2095

209











[K]

3226e+002

3224e+002

3223e+002

3221e+002

3220e+002

3219e+002

3217e+002

3216e+002

3214e+002

3213e+002

3211e+002

(a)


[K]

3870e+002

3857e+002

3845e+002

3833e+002

3821e+002

3809e+002

3796e+002

3784e+002

3772e+002

3760e+002

3747e+002

(b)


[K]

3954e+002

3911e+002

3869e+002

3826e+002

3784e+002

3741e+002

3699e+002

3656e+002

3614e+002

3572e+002

3529e+002

(c)


[K]

3956e+002

3944e+002

3931e+002

3919e+002

3907e+002

3894e+002

3882e+002

3870e+002

3857e+002

3845e+002

3833e+002

(d)













6 Conclusions






Data Availability




Acknowledgments



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia





sum119904119904119904 = 120587119863119894119904119860119869119904119878119891

(5)


sum119904119905119904 +sum119904119904119904 = 120587 (1198632119905119904 minus 1198632119894119904)4

= 1205871205721015840119901119896119905119904119863119894119904 (119863119905119904 minus 119863119894119904)2119870119865119890119904119896119897119904 + 120587119863119894119904119860119869119904119904119891(6)


1198601199001199041198941199041198632119900119904 minus 2119861119900119904119894119904119863119900119904 + 119862119900119904119894119904 = 0 (7)

Solution


where

119860119900119904119894119904 = 12058721205722119901 11989621198951199044119901211987021198651198901199041198962119897119904 +1205722119901 11989611989511990411989611990511990411990111987021198651198901199041198962119897119904 +

2120572119901119896119905119904119870119865119890119904119896119897119904 minus 1119861119900119904119894119904 = (119896119905119904 + 1205871198961198951199042119901 )

120572119901119870119865119890119904119896119897119904119863119874119878 +2119860119869119904119878119891

119862119900119904119894119904 = 1198632119900119904

(9)



119887119905119904 = 1205871205721015840119901119896119905119904119863119894119904119885119904119870119865119890119904119896119897119904 (10)





120582119904119890 = 111205820 + 2sum119899119894=1 (1120582119894) ln (119877119894119877119894minus1) (11)



(12)




120575119886120582119886119897119890119891119887119904119886V(13)


Δ120579119908 = 119875119888119906119885119904 times 119877119905ℎ 119886119897119897 (14)


Start




End

Yes

No

No





Yes



Adjust motor sizes





Δ120579119908 le 09 (119879ℎ minus 119879119886) (15)






mpe

ratu

re ri

se(∘

C)

＜ＭＰ (m)

300

250

200

150

100

50

0

0005 00055 0006 00065 0007 00075




0 1 2 3 4 5 6 7 8 9

No-

Load

line

bac

k-EM

F (V

)

200

160

120

80

40

0

minus40

minus80

minus120

minus160

minus200






Elec

trom

agne

tic to

rque

(Nm

)

0 05 1 15 2 25 3 35 4

213

2125

212

2115

211

2105

210

2095

209











[K]

3226e+002

3224e+002

3223e+002

3221e+002

3220e+002

3219e+002

3217e+002

3216e+002

3214e+002

3213e+002

3211e+002

(a)


[K]

3870e+002

3857e+002

3845e+002

3833e+002

3821e+002

3809e+002

3796e+002

3784e+002

3772e+002

3760e+002

3747e+002

(b)


[K]

3954e+002

3911e+002

3869e+002

3826e+002

3784e+002

3741e+002

3699e+002

3656e+002

3614e+002

3572e+002

3529e+002

(c)


[K]

3956e+002

3944e+002

3931e+002

3919e+002

3907e+002

3894e+002

3882e+002

3870e+002

3857e+002

3845e+002

3833e+002

(d)













6 Conclusions






Data Availability




Acknowledgments



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



Start




End

Yes

No

No





Yes



Adjust motor sizes





Δ120579119908 le 09 (119879ℎ minus 119879119886) (15)






mpe

ratu

re ri

se(∘

C)

＜ＭＰ (m)

300

250

200

150

100

50

0

0005 00055 0006 00065 0007 00075




0 1 2 3 4 5 6 7 8 9

No-

Load

line

bac

k-EM

F (V

)

200

160

120

80

40

0

minus40

minus80

minus120

minus160

minus200






Elec

trom

agne

tic to

rque

(Nm

)

0 05 1 15 2 25 3 35 4

213

2125

212

2115

211

2105

210

2095

209











[K]

3226e+002

3224e+002

3223e+002

3221e+002

3220e+002

3219e+002

3217e+002

3216e+002

3214e+002

3213e+002

3211e+002

(a)


[K]

3870e+002

3857e+002

3845e+002

3833e+002

3821e+002

3809e+002

3796e+002

3784e+002

3772e+002

3760e+002

3747e+002

(b)


[K]

3954e+002

3911e+002

3869e+002

3826e+002

3784e+002

3741e+002

3699e+002

3656e+002

3614e+002

3572e+002

3529e+002

(c)


[K]

3956e+002

3944e+002

3931e+002

3919e+002

3907e+002

3894e+002

3882e+002

3870e+002

3857e+002

3845e+002

3833e+002

(d)













6 Conclusions






Data Availability




Acknowledgments



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



mpe

ratu

re ri

se(∘

C)

＜ＭＰ (m)

300

250

200

150

100

50

0

0005 00055 0006 00065 0007 00075




0 1 2 3 4 5 6 7 8 9

No-

Load

line

bac

k-EM

F (V

)

200

160

120

80

40

0

minus40

minus80

minus120

minus160

minus200






Elec

trom

agne

tic to

rque

(Nm

)

0 05 1 15 2 25 3 35 4

213

2125

212

2115

211

2105

210

2095

209











[K]

3226e+002

3224e+002

3223e+002

3221e+002

3220e+002

3219e+002

3217e+002

3216e+002

3214e+002

3213e+002

3211e+002

(a)


[K]

3870e+002

3857e+002

3845e+002

3833e+002

3821e+002

3809e+002

3796e+002

3784e+002

3772e+002

3760e+002

3747e+002

(b)


[K]

3954e+002

3911e+002

3869e+002

3826e+002

3784e+002

3741e+002

3699e+002

3656e+002

3614e+002

3572e+002

3529e+002

(c)


[K]

3956e+002

3944e+002

3931e+002

3919e+002

3907e+002

3894e+002

3882e+002

3870e+002

3857e+002

3845e+002

3833e+002

(d)













6 Conclusions






Data Availability




Acknowledgments



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




[K]

3226e+002

3224e+002

3223e+002

3221e+002

3220e+002

3219e+002

3217e+002

3216e+002

3214e+002

3213e+002

3211e+002

(a)


[K]

3870e+002

3857e+002

3845e+002

3833e+002

3821e+002

3809e+002

3796e+002

3784e+002

3772e+002

3760e+002

3747e+002

(b)


[K]

3954e+002

3911e+002

3869e+002

3826e+002

3784e+002

3741e+002

3699e+002

3656e+002

3614e+002

3572e+002

3529e+002

(c)


[K]

3956e+002

3944e+002

3931e+002

3919e+002

3907e+002

3894e+002

3882e+002

3870e+002

3857e+002

3845e+002

3833e+002

(d)













6 Conclusions






Data Availability




Acknowledgments



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia







6 Conclusions






Data Availability




Acknowledgments



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



References

























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


electromagnetic-thermal integration design of permanent

Documents