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Dr David Staton
Motor Design Ltd., Ellesmere, Shropshire, UK
www.motor-design.com
Motor Design Ltd (MDL)

MDL formed in 1998 to:
 Develop electric motor design software
 Provide motor design consulting services
and motor design training
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Nissan LEAF Motor Simulation
 ANSYS – MDL simulation on LEAF motor
 proof the synergy of combined solution
 validates the accuracy prediction of
performance criteria on efficiency/loss maps
and drive cycle transient thermal analysis
 quickly evaluate different cooling profiles
 study to adjust the distribution of coolant
using different channel configurations
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Electromagnetic Models for LEAF Motor
 Various complexities of electromagnetic model have been
created in Maxwell & Motor-CAD EMag
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Maxwell Models for LEAF Motor
 Maxwell 2D & 3D electromagnetic models have been constructed
to calculate open circuit and on load to calculate performance
criteria such as back emf, torque-speed characteristic, torque
ripple, cogging, losses, etc.
 The 2D model was constructed by two ERASMUS students from Casino
University in Italy that were on placement at MDL
 Their work formed a tutorial from traction motor modelling using Maxwell
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Maxwell Models for LEAF Motor
Axial split PM topology to reduce eddy effects
Field distribution at rated load condition
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Motor-CAD EMag Model for LEAF Motor
 2D FEA using parametric geometric model used to give a very fast estimate of the
electromagnetic performance
 Not include exact geometric details of flux barriers/magnet slots
 More detailed final analysis possible using DFX import of actual geometry
 The simplified geometry gives relatively accurate estimates of average torque and
losses but less accurate prediction of torque ripple
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Electromagnetic Model Validation
 Some assumptions have been made
due to lack of exact data on the motor
construction and materials used
 We can use Motor-LAB with links to
either Maxwell or Motor-CAD EMag to
calculate the losses over the full
torque/speed
 Motor-LAB also automatically calculates
the optimum phase advance for either
maximum torque/amp or maximum
efficiency control
 In this case also apply a 80kW max.
power limit as in the test procedure
Motor-LAB
good match
Measured
 Optimum use of a minimum number of
FEA calculations to model saturation
and losses gives a very fast calculation
 Map calculated within a few minutes
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Motor-CAD Therm Model for LEAF Motor
 Thermal component such as the water jacket also defined
 Validated as match measured thermal transient at 50, 60, 70 & 80kW
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50kW, 60kW, 70kW and 80kW Duty Cycle
 50, 60, 70 & 80kW thermal transient set up in Motor-LAB
 Loss data then transferred to Motor-CAD Therm model
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Motor-CAD Therm Model for LEAF Motor
 cuboidal elements used
to accurately model the
winding conductive
heat transfer
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Calibration of stranded winding models
 By estimating the placement of the conductors in a slot, we can automatically
create a thermal FEA model and check if the conduction heat transfer in the
slot matches the 3D cuboidal resistance model
 Calibration of effective thermal conductivity of copper, enamel, impregnation
and air (no calibration - excellent results below)
 To make the calibration, we remove end effects in the lumped circuit model
and then apply them again after calibration.
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LEAF Efficiency Map & US06 Drive Cycle
 Using Motor-LAB all the points on US06 drive cycle within efficiency map
can be calculated in a few minutes
 Accounting for saturation, optimum field weakening angle and accurate
estimate off losses
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Efficiency/Loss Maps in Motor-LAB
 Efficiency and loss maps can be plotted
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US06 Drive Cycle in Motor-LAB
 Torque vs time
 Speed vs time
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US06 Drive Cycle in Motor-CAD Therm
 transient loss data is calculated across the duty cycle in Motor-LAB and
transferred to Motor-CAD for thermal analysis
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US06 Thermal Transient in Motor-CAD
 Ten cycles of US06 thermal transient takes less than 8 minutes to
compute (Lenovo T440)
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More Extensive FEA/CFD Using ANSYS
 Automated links to ANSYS helps
speed up creation of 2D/3D FEA and
CFD models to make more detailed
calculations
 3D electromagnetic effects
 CFD to check/calibrate flow
calculations
 AC loss in winding
 etc.
Fluent
Motor-CAD
SpaceClaim
Maxwell
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Modeling Water Jacket Cooling Channels
Path Lines
Static Pressure
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Modeling Water Jacket Cooling Channels
Distribution of coolant using different channel configurations
Temperature Profile
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Reduced Node Modelling of LEAF Motor
 useful for full system simulation
 matrix reduction method to calculate a smaller R-C network that gives same
transient thermal response
 keep enough nodes to give good indication of temperatures across entire model
 full model of 65 nodes versus 7 nodes in reduced model
Full Node Model
Reduced Node Model
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Reduced Node Modelling of LEAF Motor
 Retains full model accuracy in steady state
 Reduced model thermal transient very good agreement with full model
 Solves in a fraction of time of the full model
Nodes
% of Total nodes
(65)
Steady State accuracy
(%)
Transient Time (15 Transient
seconds for full)
Accuracy
7
10
99.75
< 2 seconds
Steady State
Excellent
Transient
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Comparison of US06 duty cycle
 compare the complex US06 duty cycle with full model against
the 7 node model
 the results compare very well
Full node model
Reduced node model
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Summary
 Demonstrated a range of integrated analytical and numerical
software tools we use to perform electromagnetic and
thermal design of electric motors
 Used Nissan LEAF motor to demo tools used
 The different tools have different levels of complexity and
different calculation and setup speeds
 For complex duty cycle thermal analysis its is best use the
faster analytical network solution with the slower numerical
tools used to help set up and calibrate the models
Acknowledgments:
- Mike Slack
- Manoj Nagulapally
- Eddie Chong
- ANSYS CFD Expert, UK
- ANSYS CFD Expert, USA
- MDL CFD Expert, UK
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MOTOR DESIGN LIMITED
Thank you for your attention!
Questions are welcomed

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