EVS28 KINTEX, Korea, May 3-6, 2015 Development and performance investigation of 60kW induction motor with copper diecasting rotor for electric vehicle propulsion applications Yondo Chun, Pilwan Han, Jaehak Choi Korea Electrotechnology Research Institute Changwon-si, Gyeongsangnam-do, Korea ydchun@keri.re.kr
Introduction I. Due to the growing popularity of hybrid and electrical vehicles, traction electric motors are becoming common in automotive applications. II. III. IV. This paper summarizes the development process and the investigation of 60kW induction motor for electric vehicle Performance improvement of an induction motor using copper diecasting based on multi-gate process is presented. The electromagnetic, thermal, mechanical design and analysis results are also introduced to satisfy the design and the performance requirements. V. The experimental tests are also carried out for the validity of EV traction motor design. 2
Technology for high speed traction motors Design & Analysis - Optimum design for electro-magnetic field - Analysis of losses - Bearing technology - Structure & vibration analysis (rotor) Manufacture Technology - Motor frame design with cooling method - Technology for copper rotor - Improved manufacture and assembly technology - Cooling structure & heat analysis Control Technology Protection Module Test & Evaluation - Controller design for inverter - Control algorithm design - The Establishment and operation of dynamo system TEST SAMPLE LOAD MACHINE 3
Performance requirement Performance requirement Items Characteristic Unit Value Output Max. condition Continuous condition Power kw 60@3000~12,000rpm Torque Nm 190@0~3,000rpm Power kw 30@3000~12,000rpm Torque Nm 95.5@0~3,000rpm Cooling Cooling method - Water cooling (water jacket) Voltage Line to Line V 130Vrms @ 3,000rpm 220Vrms @ 12,000rpm
Electro-magnetic design Electro-magnetic Analysis u In- house Program (KERI) u SPEED Program (Magsoft) u FEM Program 5
Electro-magnetic design GA Optimum design 6
Electro-magnetic design GA Optimum design GA Generation : Design condition : 30kW @ 3,000rpm : Interesting region (cost 250 / Eff. 91% ) 7
Electro-magnetic design GA Optimum design Design variable Unit Initial model Variable Scope Low High Optimum model Remarks C0 [10 3 J/m 3 ] 235 200 250 212.4 Output Coefficient Bts [T] 1.677 1.50 1.80 1.695 Stator teeth flux density Btr [T] 1.738 1.50 1.80 1.724 Rotor teeth flux density Bg [T] 1.22 1.00 1.30 1.16 Airgap flux density Bcs [T] 1.26 1.10 1.50 1.395 Stator yoke flux density Js [A/mm 2 ] 12.55 10.0 13.5 11.0 Stator current density Jr [A/mm 2 ] 10.5 7.0 11.0 7.99 Rotor current density λ - 1.34 1.1 1.5 1.273 Stack length(l)/pole pitch(τp) Eff. % 90.2 - - 91.1 Efficiency Material cost 236,000 - - 242,900 Electrical steel[ 2,000/kg] + copper[ 11,000/kg] 8
Electro-magnetic design FEM Analysis (30kW / 3,000RPM) Output power Current Torque Coreloss 9
Mechanical design Mechanical Strength Analysis Maximum stress: rotor core184[mpa], rotor bar[20mpa], end ring[24mpa] (Yield strength : core 380MPa, copper: 55MPa) - Safety factor : 2 Rotor core Rotor bar End ring 10
Mechanical design Modal Analysis Rotor Modelling Natural freg. : 20400.00 [rpm] Damping : 0.00e+000 1st : 20,400 [rpm] Vertical Natural freg. : 44214.00 [rpm] Horizontal Damping : 0.00e+000 2nd : 44,214 [rpm] Vertical Horizontal 11
Mechanical design Campbell Diagram Analysis Operating region Resonance region 12
Thermal analysis 3D analysis model Ø Thermal analysis by using STAR-CCM+ Commercial program 30kW IM operating condition (Eff. : 92.5% - Total loss : 2.7kW) Rated Power Operating Speed Coolant Flow Rate Coolant Inlet Temp. Amb. Temp. 30 kw 3,000 rpm 3.8 lpm 30 o C 30 o C Cooling Type Coolant Only (1) (1) Boundary condition and heat source characteristics (1) Convection boundary con. h = 10 W/m 2 K, T amb = 30 o C (2) Mechanical loss 48 W (4) (3) Stator copper loss 1,045 W (4) Rotor copper loss 444 W (3) (5) (6) (5) Iron loss 565 W (6) Stray load loss 337 W 13
Thermal analysis 3D thermal analysis and test at 30kW / 3,000 rpm Top view Winding Temp. (saturation : 134 C) Saturation Temp. : 109.5 Comparison between analysis and experiment Parts Coil Stator Rotor Cage Max. Temp. (CFD) 110.3 (+0.8 ) 100.6 128.66 128.67 Max. Temp. (Test] 109.5 - - - 14
Copper die-casting CFD analysis of copper die-casting mold First design Improved design 15
Copper die-casting Process for copper die-casting rotor a. Setting b. Pre-heating c. Melting copper d. Pouring molten copper e. Extracting rotor f. Copper rotor g. Grinding rotor for assembling 16
Copper die-casting Life time test of die-casting mold 17
Assembling prototype Process for motor prototype Core and die-casing Inserting shaft Grinding rotor Balancing rotor Winding Inserting stator Assembling rotor Completion 18
Testing prototype Test Facility (60kW-15,000rpm) Cooling facility Inverter for load Transformer For load Load motor Prototype 19
Testing prototype Test Results (30kW) on saturation -Output power and efficiency- -Torque and current- Brazing_Current[A] Brazing_Torque[Nm] Diecast_Current[A] Diecast_Torque[Nm] Brazing_Efficiency[%] Brazing_Output[kW] Diecast_Efficiency[%] Diecast_Output[kW] Ref. Speed (rpm) Brazing Efficiency[%] Diecasting Efficiency[%] Eff. Difference (Brazing- Diecasting) 1,000 82.4 79.4 3.0 2,000 88.3 86.8 1.5 3,000 90.2 89.1 1.1 4,000 90.5 89.4 1.1 5,000 90.4 89.3 1.1 6,000 90.0 88.9 1.1 7,000 89.7 88.4 1.3 8,000 89.1 87.5 1.6 9,000 88.5 86.7 1.8 10,000 87.9 85.7 2.2 11,000 87.0 85.0 2.0 12,000 86.2 84.5 1.7 Ref. Speed (rpm) Brazing Current [Arms] Diecasting Current [Arms] Curr. Difference (Brazing- Diecasting 1,000 174.7 180.1-5.4 2,000 173.2 178.8-5.6 3,000 176.6 182.1-5.5 4,000 161.4 163.4-2.0 5,000 148.6 150.8-2.2 6,000 139.8 141.9-2.1 7,000 132.1 133.9-1.8 8,000 125.8 127.9-2.1 9,000 119.8 123.0-3.2 10,000 115.5 119.2-3.7 11,000 111.4 113.6-2.2 12,000 106.3 109.3-3.0 20
Testing prototype Test Results (max : 60kW), non-saturation, Brazing 21
Testing prototype Test Results (max : 60kW), non-saturation, Diecasting 22
Testing prototype Test Results (max : 60kW), non-saturation, Diecasting 91 87 90 82 75 70 60 23
Traction motor test facility in KERI 150kW 15krpm 60kW 15krpm 250kW 12krpm 60~250kW Dynamo System 250kW Battery Simulator Temp. Range : -50~150 Hum. Range : 30%~98% Environment Chamber Control Room 24
Conclusion u In this paper, the development process and investigation of 60kW induction motor for electric vehicle are introduced u Traction motors have a lot of design points due to various driving conditions such as continuous and maximum power operating u Electromagnetic dimensions of motor were decided from IM equivalent circuit and verified from FEM analysis in various operating condition u Mechanical designs are carried out by considering structure safety & vibration response and thermal conditions from analysis results. u The experimental tests are also carried out on continuous (30kW) and maximum (60kW) operating conditions for the validity of EV traction motor design. 25