Electric Machine Design for Automotive Applications. Dr David Staton

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1 Electric Machine Design for Automotive Applications Dr David Staton

2 Topics Automotive Electrical Traction Fast Drive Cycle Analysis Automotive Traction Motor Design Example Summary 109

3 Automotive Electrical Traction Range of configurations under development Mild, Series, Parallel and Plugin Hybrid Battery Electric and Range Extender Main design drivers: Efficiency Power Density Cost 110

4 Many Possible Motor Design Configurations Many choices to be made when designing a motor: BPM, Induction, Synchronous Reluctance, SRM. Design Variables Slots/poles, Magnet Type, IPM design, Dimensions Winding Type Distributed, Tooth Wound, Bar/Hairpin, Litz, Cu/Al.. Cooling Type Air, Water Jacket, Rotor Fluid, Slot Oil, Oil Spray 111

5 Dynamic Operation The operation of these machines is very dynamic and consideration of performance across the full torque/speed operating envelope is required Modelling tools need to support this In order to optimize the motor design for particular drive cycles we need a fast way to analyze the motors electromagnetic and thermal performance on the required duty cycle load 112

6 Key Features to Enable Fast Drive Cycle Analysis Calculation of the efficiency map using: Fast electromagnetic calculation Minimum number of electromagnetic calculations Accurate but fast loss calculations including complex losses like magnet loss (with segmentation) and proximity losses Automatic calculation of drive control strategy (maximum torque/amp) Calculation of the drive cycle thermal transient using a lumped circuit solver: Losses from the efficiency map Losses scaled with temperature 113

7 Motor-CAD for Fast Duty Cycle Analysis Motor-CAD EMag, Therm and Lab modules developed to enable fast drive cycle/duty cycle analysis in an integrated software EMag: calculate flux-linkage & loss data with minimum 2D FEA solutions Lab: Use FEA data to calculate & plot efficiency & loss maps. Then define duty cycle torque & speed vs time and calculate loss vs time data from loss maps Therm: Pass loss v time data to lumped circuit thermal model for thermal transient calculation 114

8 Product Development Workflow Workflow much larger topic area than detailed motor design Motor-CAD useful for all areas of the workflow and not just detailed design Motor-CAD used by both motor designers and application/system/test engineers Automated links to other software (ANSYS Mechanical, Matlab Simulink, Optimisation) useful to speed up the workflow Application Engineer Motor Design Engineer Motor Type & Topology + Initial Sizing Design Optimisation & Drive Cycle Analysis Test & Design Model Engineer Calibration Reduced Order Models & Flux Linkage/Loss Maps System Engineer 115

9 Manufacturing Data Built into Models Many manufacturing uncertainties that affect temperature rise: Goodness of effective interface between stator and housing How well the winding is impregnated or potted Leakage of air from open fin channel blown over machines Cooling of the internal parts in a TENV and TEFC machine Heat transfer through the bearings etc. Test program over 18 years developing data to quantify such issues: Set default parameters in Motor-CAD giving good level of accuracy without the user having done extensive calibration using testing of their own machines Also automated choice of model type to give high accuracy Equivalent interface gap that is useful to non heat transfer specialist as easy to visualise Example of assistance given to set stator lamination to housing interface thermal resistance Interface resistance and conductance data that is suitable for thermal experts 116

10 Automotive Traction Motor Design Examples A selection of published design examples for automotive traction motors are given next 117

11 Toyota PRIUS Efficiency Map Validation Validation based on Toyota 2004 Prius test data from ORNL published at PEMD 2012 Excellent match measured and calculated efficiency map Motor-LAB Calculation Measured Efficiency Map 118

12 Performance Prediction for Tesla Model S Motor Data from teardown analysis of the Tesla Model S electric motor Copper rotor induction motor with potted end windings and water cooled stator and rotor 119

13 Evoque_e / Concept_e Innovate UK Project MDL project member with JLR to develop for 3 demonstrators: MHEV (Range Rover Evoque): Mild Hybrid with 48V lithium ion battery pack 15 kw crank integrated motor with disconnect clutch sandwiched between the prototype diesel engine (90 PS) and 9 speed transmission PHEV (Range Rover Sport): Plug-In Hybrid with prototype petrol engine (300 PS) and 8 speed transmission longitudinally mounted within a Range Rover Sport 150kW electric motor 320-volt lithium ion battery packaged in the boot BEV (Range Rover Evoque): Bespoke research demonstrator based on JLR aluminium vehicle architecture Modified underbody to mount the 70 kwh HV lithium ion traction battery and electric axle drive (EAD) units Front drive unit with single speed transmission coupled with an 85 kw electric motor Rear drive unit features a twin speed transmission coupled with a 145 kw electric motor 120

14 Evoque_e / Concept_e BEV Design Ferrite magnets and aluminium winding 121

15 Evoque_e / Concept_e MHEV Design Ferrite spoke magnets with novel rotor construction M. Kimiabeigi, J. D. Widmer, R. Long, Y. Gao, J. Goss, R. Martin, T. Lisle, J.M. Soler Vizan, A. Michaelides, B. Mecrow On Selection of Rotor Support Material for a Ferrite Magnet Spoke Type Traction Motor, IEMDC 2015, USA 122

16 High Performance Motorsport Motor High torque density motor for motorsport Magnet Loss (Over One Cycle) Open Circuit On-Load Iron Loss (On-Load) 123

17 High Performance Motorsport Motor Complex cooling system with multiple cooling circuits Calculated efficiency map and drive cycle analysis for LeMans circuit in few mins Motor Speed & Torque (LeMans) Fast duty cycle analysis ideal for sizing of motor for race circuit and/or size the required cooling system Motor Speed Motor Torque 20 Laps of LeMans Circuit 124

18 Performance Prediction for Nissan LEAF Motor Much data available on internet for Nissan LEAF motor Developed models to validate & demonstrate software tools for modelling traction applications 125

19 Performance Prediction for Nissan LEAF Motor Predicted efficiency map validated by test data Motor-LAB Thermal model validated by 50kW, 60kW, 70kW, 80kW thermal transient test data good match Measured 126

20 Drive Cycle Prediction (Nissan LEAF) Prediction of efficiency map and 10 repetitive US06 Drive Cycle thermal transient in a few minutes Total Loss Torque vs time Copper Loss Iron Loss Speed vs time 127

21 Continuous Software Development Software has been under continual development over the past 18 years with feedback from its hundreds of users worldwide New features driven by user requirements Work closely with our customers Many users in various industrial sectors Automotive (Bosch, BMW, Daimler, GM, JLR, Nissan, Porsche, Remy, Renault...) Aerospace (Ametek, BAE, Eaton, Thales, Safran, Goodrich, UTC.) Industrial (ABB, Emerson, Regal Beloit, SEW, Siemens. ) Traction (ABB, Bombardier, Caterpillar, GE, Komatsu. ) Renewable (Alstom, Gamesa, GE, Siemens, Vestas ) Universities (Bristol, Manchester, Newcastle, Nottingham, Sheffield ) 128

22 Summary Machine design choices are complex and state of the art modelling tools are required to inform these choices Motor-CAD is fast to simulate and constantly validated against test data It can be used by experts and non-experts in the various physical domains Design choices can be compared very quickly even with complex drive cycle analysis 129

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