Christian Doppler Labor, TU Graz 12. Dezember 2007

Transcription

1 Christian Doppler Labor, TU Graz 12. Dezember 2007 Verlustberechnung und experimentelle Validierung bei hochausgenützten Permanentmagnet-Synchronmaschinen mit Zahnspulenwicklungen und Feldschwächbetrieb & Csaba Deak Darmstadt University of Technology Dept. of Electrical Energy Conversion Landgraf-Georg-Strasse 4, D-64283, Darmstadt Energiewandlung 1 / 57

2 Overview - Introduction - Considered PM synchronous motors - Basic design - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 2 / 57

3 Modular synchronous machine Permanent - Magnet motors: - high torque - reduced active mass - reduced rotor losses Tooth-wound coils: - short winding overhang - small resistance (reduced stator losses) - compact design Design of 3 PM motors: - Constant power: 45 kw - Phase voltage: 230V - Rated speed: 1000 /min - Maximum speed: 3000 /min 3 Energiewandlung 3 / 57

4 High-torque Antriebe für höhere Drehzahlen - Zahnspulentechnologie und Permanentmagnetläufer : - kompakte Statoren - niedrige Stromwärmeverluste - hohe Induktivität für gute Feldschwächbarkeit - hohe Kraftdichte - Genutzt für Servoantriebe, High-torque-Antriebe! - Auch nutzbar für Industrieantriebe mit höheren Drehzahlen? Beispiel: Motor A 45 kw /min Hz 400 Hz 430 Nm Statorstrom 1000/min 3000/min d-strom q-strom Energiewandlung 4 / 57

5 High-torque Antriebe für höhere Drehzahlen - Hohe Ausnützung im Vergleich Asynchron PM Synchron Wassermantelkühlung PN 2π M N M N C = = ~ ~ k 2 2 d l n d l V si Fe si Fe EW: Entwurf aktiv w A B Energiewandlung 5 / 57

6 Considered PM synchronous motors Motor A q = ½ Motor C Magnet Magnet - 7 magnets / pole - 7 magnets / pole Motor B Motor D - 1 magnet / pole Magnet - 1 magnet / pole Magnet Surface mounted magnets 24 semi-closed stator slots / 16 poles Energiewandlung 6 / 57 Buried magnets

7 Stator yoke Considered PM synchronous motors Motor E Motor G Stator tooth q = ¼ Tooth wound coil Magnet Rotor iron - 7 magnets / pole - 7 magnets / pole Motor F Motor H - 1 magnet / pole Magnet - 1 magnet / pole Magnet Surface mounted magnets 24 open stator slots / 16 poles Energiewandlung 7 / 57 Buried magnets

8 High-torque Antriebe für höhere Drehzahlen Alternative Motorkonzepte: 16-polige Statoren Variante A: q = 0.5 Variante G: q = 0.25 Wirkungsgrad *) 93.7% / 95.3 % 92.8 % / 93.3 % bei 45 kw 1000 / 3000/min 1000 / 3000/min Magnettemperatur 87 C 115 C *) gemessen direkt bei: Umrichterspeisung, Wärmeklasse F, 45 C Kühlwasser Energiewandlung 8 / 57

9 Zwei alternative Motorkonzepte: 16-polige Statoren A-D: q = 0.5 (links) E-H: q = 0.25 (rechts) Kompakte Stator-Kupfer-Wicklung geringere Stromwärmeverluste Kühlmantel Zahnspule Variante A-D: Runddrahtnadelwicklung Variante E-H: Aufsteckspulen titel η = % Stator-Wicklung Blechpaket 45 kw /min 16 Pole, Motormasse 200kg Energiewandlung Prof. Dr.-Ing. habil. A. Binder

10 Zukunftsmarkt: E-Antriebe für Hybrid-Automobile? titel Energiewandlung Prof. Dr.-Ing. habil. A. Binder

11 Overview - Introduction - Considered PM synchronous motors - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 11 / 57

12 Geometry and winding design Motor A Stator tooth Stator yoke Tooth-wound coil Magnet Bandage Motor A X G Stator outer diameter (mm) Stator bore diameter (mm) Active length (mm) Number of stator slots Number of poles Air gap (mm) (=δ 0 ) Bandage (mm) Motor A X G Nr. of turns per phase Nr. of parallel connections Coils per pole and phase Slot fill factor Winding factor (ν = 1) Phase resistance (mω)* * At 145 C Rotor yoke Cooling duct Energiewandlung 12 / 57

13 Motor X Geometry and winding design Stator tooth Stator yoke Tooth-wound coil Magnet Bandage Cooling duct Rotor yoke Motor A X G Stator outer diameter (mm) Stator bore diameter (mm) Active length (mm) Number of stator slots Number of poles Air gap (mm) (=δ 0 ) Bandage (mm) Motor A X G Nr. of turns per phase Nr. of parallel connections Coils per pole and phase Slot fill factor Winding factor (ν = 1) Phase resistance (mω)* * At 145 C Energiewandlung 13 / 57

14 Geometry and winding design Motor G Stator tooth with winding Tooth-wound coil Intermediate tooth without winding Optimized rotor surface Motor A X G Stator outer diameter (mm) Stator bore diameter (mm) Active length (mm) Number of stator slots Number of poles Air gap (mm) (=δ 0 ) Bandage (mm) Motor A X G Nr. of turns per phase Nr. of parallel connections Coils per pole and phase Slot fill factor Winding factor (ν = 1) Phase resistance (mω)* * At 145 C Stator yoke Magnet Rotor yoke Cooling duct Energiewandlung 14 / 57

15 Overview - Introduction - Considered PM synchronous motors - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 15 / 57

16 No-load operation Field distribution Motor A Air gap flux density Magnet segmentation Flux density ( T ) Fundamental Slot opening Circumferential coordinate ( mech. degree ) B δ0(1) = T Energiewandlung 16 / 57

17 No-load operation Field distribution Motor X Air gap flux density Magnet segmentation Fundamental Flux density ( T ) Slot opening Circumferential coordinate ( mech.) B δ0(1) = T Energiewandlung 17 / 57

18 No-load operation Field distribution Motor G Air gap flux density Flux density ( T ) Slot opening Fundamental Circumferential coordinate ( mech. degree ) B δ0(1) = 0.87 T Energiewandlung 18 / 57

19 Cogging torque (Nm) Cogging torque Rotor position ( mech.) No-load and load torque Motor A Motor B Motor C Torque (Nm). Torque ripple at rated speed Motor A Motor B Motor C Rotor position ( mech) Motor A U s j X s I s ϕ γ = 16 el I s γ I sd q-axis R s I s U p I sq d-axis Phasor diagrams at rated speed Motor X q-axis U s γ = 20 el j X s I s ϕ I s γ I sd R s I s U p I sq d-axis 50 V 50 A U s j X s I s γ = 18 el ϕ Motor G I s γ I sd q-axis R s I s U p I sq d-axis Energiewandlung 19 / 57

20 Comparison of the designed motors Speed (1/min) Motor A Motor X Motor G Constant power (kw) Phase voltage (V) Phase current (A) Power factor Torque (Nm) Power density / active mass (kw/kg) Torque ripple (% of rated torque) Torque density / active mass (Nm/kg) Thermal load A J (A/cm A/mm 2 ) Energiewandlung 20 / 57

21 Overview - Introduction - Considered PM synchronous motors - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 21 / 57

22 Motor A 2D thermal Models ϑ amb air & resin conductor wedge bandage slot insulation conductor insulation (thermal class F) magnet Water jacket cooling: - inlet temperature ϑ in = 38 C - outlet temperature ϑ out = 43.3 C - ambient temperature ϑ amb = 44.2 C Energiewandlung 22 / 57

23 Motor X 2D thermal Models ϑ amb air & resin conductor bandage magnet wedge slot insulation conductor insulation (thermal class F) Water jacket cooling: - inlet temperature ϑ in = 38 C - outlet temperature ϑ out = 43.3 C - ambient temperature ϑ amb = 44.2 C Energiewandlung 23 / 57

24 Motor G 2D thermal Models ϑ amb air & resin conductor wedge slot insulation conductor insulation (thermal class F) magnet Water jacket cooling: - inlet temperature ϑ in = 38 C - outlet temperature ϑ out = 43.3 C - ambient temperature ϑ amb = 44.2 C Energiewandlung 24 / 57

25 Loss distribution Speed (1/min) Motor A Motor X Motor G 3000 Copper Losses (at 145 C) * (W) Iron losses in teeth * (W) Iron losses in yoke * (W) Magnet losses * (W) Friction losses (W) Total losses * Sinus + inverter supply: Analytical calculation Energiewandlung 25 / 57

26 Heat distribution at rated speed & torque Rated speed Motor A Maximum speed ϑ [ C C ] ϑ [ C C ] Hotspot: ϑ hotspot = 144 C Δϑ hotspot = 104 K Average: ϑ average = 119 C Δϑ average = 79 K Hotspot: ϑ hotspot = 133 C Δϑ hotspot = 93 K Average: ϑ average = 112 C Δϑ average = 72 K Thermal class F: Δϑ average,lim = 105 K; ϑ average,lim = 145 C; Δϑ hotspot,lim = 115 K; ϑ hotspot,lim = 155 C Energiewandlung 26 / 57

27 Heat distribution at rated speed & torque Rated speed Motor X Maximum speed ϑ [ C C ] ϑ [ C C ] Hotspot: ϑ hotspot = 203 C Δϑ hotspot = 163 K Average: ϑ average = 155 C Δϑ average = 115 K Hotspot: ϑ hotspot = 239 C Δϑ hotspot = 199 K Average: ϑ average = 181 C Δϑ average = 141 K Thermal class F: Δϑ average,lim = 105 K; ϑ average,lim = 145 C; Δϑ hotspot,lim = 115 K; ϑ hotspot,lim = 155 C Energiewandlung 27 / 57

28 Heat distribution at rated speed & torque Rated speed Motor G Maximum speed ϑ [ C C ] ϑ [ C C ] Hotspot: ϑ hotspot = 110 C Δϑ hotspot = 70 K Average: ϑ average = 100 C Δϑ average = 60 K Hotspot: ϑ hotspot = 98 C Δϑ hotspot = 58 K Average: ϑ average = 89 C Δϑ average = 49 K Thermal class F: Δϑ average,lim = 105 K; ϑ average,lim = 145 C; Δϑ hotspot,lim = 115 K; ϑ hotspot,lim = 155 C Energiewandlung 28 / 57

29 Design features - Torque density: 5.56 Nm/kg (motor A & X), 4.77 Nm/kg (motor G) - Power density: 0.58 kw/kg (motor A & X), 0.5 kw/kg (motor G) - Increased power factor due to negative d-current supply: (motor A), (motor X), (motor G) - 2D thermal models (overhang losses in slots included): - temperature reserve: 10 K (motor A) & 45 K (motor G) - overheating by motor X Energiewandlung 29 / 57

30 Overview - Introduction - Considered PM synchronous motors - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 30 / 57

31 Built prototype rotors Rotor 1 with surface mounted segmented magnets Magnets Gluing of the magnets Filling the pole gaps Bandage Rotor lamination Rotor 3 with buried segmented magnets Magnets Inserting the magnets 6 Packages Assembling 6 x Rotor lamination Energiewandlung 31 / 57

32 Vermeidung von Magnetverlusten: Segmentierte NdFeB-Magnete, Rotor 1 Permanentmagnete erzeugen verlustfrei das Magnetfeld Oberflächenmagnete Kohlefaserbandage Magnete titel Welle Rotorblechpaket Energiewandlung Prof. Dr.-Ing. habil. A. Binder

33 Built prototype rotors Rotor 2 with surface mounted non-segmented magnets Energiewandlung 33 / 57

34 Stator A-DA Cu-wire Winding Built prototypes Cooling jacket Heating of the cooling jacket and mounting it on the stator lamination Stator lamination Stator E-HE Preformed coil Winding Cooling jacket Stator lamination Energiewandlung 34 / 57

35 Built prototype stators Cooling water Inlet / Outlet Stator A-D Cooling jacket Outer housing Winding overhang impregnation Stator E-H Energiewandlung 35 / 57

36 Gemessene Motoren Stator A-D Kühlanlage Stator E-H Wicklung Rotor Stator A-D A B C Rotor 1 Rotor 3 E-H E F G Magnet Energiewandlung 36 / 57

37 Built prototype machines Stator A-DA Stator E-HE Rotor 1 with surface segmented magnets Rotor 3 with buried segmented magnets End shields Bearing Encoder Cu- Brushes Thermal sensors Supply cables Support Energiewandlung 37 / 57

38 Overview - Introduction - Considered PM synchronous motors - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 38 / 57

39 Rotor losses Permanent - Magnet motors with concentrated windings Increased eddy current losses in the rotor magnets: - air gap field pulsations due to the slot openings - flux pulsations in the magnets at load operation Segmented Magnets 7 PM segments 1 Pole Calculated: 8 PM motors A, B, C, D, E, F, G, H; Measured: 6! (2 Stators & 4 Rotors): Constant power: 45 kw Rated speed: 1000 rpm Maximum speed: 3000 rpm Energiewandlung 39 / 57

40 1000 rpm, no-load operation Flux density for Motor A B(x) at upper surface FEMAG-DC (no eddy currents considered!) Energiewandlung 40 / 57

41 1000 rpm, no-load operation Flux density for Motor A Upper surface Middle surface Bottom surface FEMAG-DC (no eddy currents considered!) Energiewandlung 41 / 57

42 Flux density at no-load operation Motor A Motor B Flux density Motor C Motor D 1000 rpm, upper surface FEMAG-DC (no eddy currents considered!) Energiewandlung 42 / 57

43 Flux density at load operation Motor A Sinusoidal current Motor B Motor C Motor D 1000 rpm, upper surface FEMAG-DC (no eddy currents considered!) Energiewandlung 43 / 57

44 Loss calculation methods Method 1: 1 FEMAG-DC & Analytical Formula Vector potential Current density Alternating current density b M Losses in magnets J z ( x) dx = 0 b ~ b ~ Considered in each of the three surfaces (upper, middle, bottom) Energiewandlung 44 / 57

45 Loss calculation methods Method 2: 2 FEMAG DC - Version 05/ No reaction field of eddy currents considered - Maxwell equations r r rote = B / t r J r = κe - Fast calculation - For magnets with rather low conductivity (small eddy currents) Method 2 is similar to Method 1, but is considered over the magnet cross section and not only in the three surfaces A M J z ( x, y) dx dy = 0 Energiewandlung 45 / 57

46 Loss calculation methods Influence of eddy current reaction field Penetration depth: d E = κ Mg π 1 f B,Mg μ Mg Motor A Ratio b Mg / d E 1 no eddy current reaction field b Mg,A Ex.: n = 3000 rpm; f s = 400 Hz; f B,Mg = 1200 Hz (q = ½) Motor A b Mg,A = 3.6 mm Motor B b Mg,B = 27.3 mm Motor B κ Mg,A = S/m d E,A = 17.8 mm κ Mg,B = S/m d E,B = 21.6 mm b Mg,B b Mg,A / d E,A = 0.2 b Mg,B / d E,B = 1.26 Energiewandlung 46 / 57

47 Loss calculation methods Method 3: 3 2D Time-step calculation - Reaction field of eddy currents considered - Full set of Maxwell equations r rote r roth r J = r = B / t r = κe r J r B r = μh - For general purpose up to medium frequencies valid - Very time consuming Energiewandlung 47 / 57

48 350 Loss calculation methods No-load 1000 rpm Comparison 350 No-load 3000 rpm 300 Method1: FEMAG + Analytical Method2: FEMAG Method3: Time stepping 300 Method1: FEMAG + Analytical Method2: FEMAG Method3: Time stepping P Mg [W] P Mg [W] A B C D G H A B C D G H Motor A Motor B Motor C Motor D Motor G Motor H q = ½ Energiewandlung 48 / 57 q = ¼

49 P Mg [W] Load 1000 rpm Loss calculation methods Method1: FEMAG + Analytical Method2: FEMAG Method3: Time stepping Comparison Sinusoidal current P Mg [W] Load 3000 rpm Method1: FEMAG + Analytical Method2: FEMAG Method3: Time stepping 0 0 A B C D G H A B C D G H Motor A Motor B Motor C Motor D Motor G Motor H q = ½ Energiewandlung 49 / 57 q = ¼

50 Overview - Introduction - Considered PM synchronous motors - Electromagnetic performance - Thermal analysis - Built prototypes - Rotor loss calculation methods - Loss estimation from thermal measurements - Conclusions Energiewandlung 50 / 57

51 Loss estimation from thermal measurements Losses at adiabatic heating Temperature [ C] Losses: Δt Magnet temperature Δϑ Time [min] P = m c dϑ/dt Motor A: 1000 rpm load operation Motor A Temperature sensor Motor G Useful only as the ratio of the dϑ/dt values by the different motor configuration!! Energiewandlung 51 / 57

52 90 Loss estimation from thermal measurements Comparison (all values related to Motor A, 1000 rpm, no-load operation P Mg0,A ) No- load 1000 rpm 90 No- load 3000 rpm Calculated Measured Calculated Measured P Mg / P Mg0,A Losses in rotor iron. bridge and magnets P Mg / P Mg0,A Losses in rotor iron. bridge and magnets A B C E F G A B C E F G Motor A Motor B Motor C Motor E Motor F Motor G q = ½ q = ¼ Energiewandlung 52 / 57

53 P Mg / P Mg0,A Loss estimation from thermal measurements Comparison (all values related to Motor A, 1000 rpm, no-load operation P Mg0,A ) Load 1000 rpm Calculated Measured Losses in rotor iron. bridge and magnets A B C E F G P Mg / P Mg0,A Load 3000 rpm Calculated Measured Losses in rotor iron. bridge and magnets A B C E F G Motor A Motor B Motor C Motor E Motor F Motor G q = ½ q = ¼ Energiewandlung 53 / 57

54 Erwärmung rmung bei Nennleistung : Motor F Temperature rise Δϑ [K] Temperature [ C] Winding and Magnet temperature Magnet A-S B-S Slot Outlet Inlet Time [min] Winding and Magnet temperature rise Magnet A-S B-S Slot Time [min] I s = A; U s = V; cosϕ = 0.64; I s = 73.9 A; U s = 231 V; cosϕ = 0.99; M = Nm; P mech = 45.1 kw; P d = 5.34 kw M = Nm; P mech = 45.1 kw; P d = 6.19 kw n = 1000 / min - Kühlung: 6.6 l/min n = 3000 / min Temperature rise Δϑ [K] Temperature [ C] Winding and Magnet temperature Magnet A-S B-S Slot Outlet Inlet Time [min] Winding and Magnet temperature rise Magnet A-S B-S Slot Time [min] Energiewandlung 54 / 57

55 Conclusions - 3 loss calculation methods: FEMAG-DC & analytical formula FEMAG-DC - 8 motors : 2 Stators (q = ½ ; q = ¼ ) Time stepping 4 Rotors (segmented/non-segmented; surface/buried) - Eddy-current losses in magnets are possible to be calculated with DC method (no eddy current reaction field) due to the rather low conductivity of rare-earth magnets - Loss estimation from adiabatic thermal heating is possible mainly for surface-mounted permanent magnets - For buried magnets: influence of bridge losses to be investigated further Energiewandlung 55 / 57

56 Verlustberechnung und experimentelle Validierung bei hochausgenützten Permanentmagnet-Synchronmaschinen mit Zahnspulenwicklungen Thank you for your attention! titel Energiewandlung Prof. Dr.-Ing. habil. A. Binder