Due to a continued concern on the external dependence of permanent magnets in Europe, induction technology is being pushed beyond its limits to maximise performance. With novel materials, material characterisation and multi-domain design, power-speed capability of laminated rotor induction motors can match that typically associated with surface permanent magnet machines, at a fraction of the cost. This session reviews the findings relating to lower cost induction motors, highlighting how they can successfully be used as an alternative to permanent magnets.

1. Innovative Developments
of Induction Motors
Technical Panel
International Copper Association
Ansys
Denis Ferranti, Wieland
Nottingham University
Organised by
1

2. 2

3. Agenda
Introduction
Innovations in Design and Modelling
Innovations in Manufacturing
Innovations in Materials and Applications
Q&A
3

4. Organised by
Advanced
INDUCTION
MOTOR
PLATFORM
4
 Zero porosity die
cast copper
rotor
 Fabricated
copper rotor
 Motor design
 Motor
manufacturing
 Hosting &
Communication

5. Organised by
Objectives
5
Create an ecosystem
of experts and
industries active in
the induction
technology.
Exchange regularly on the
activities carried out by members.
Share intelligence on technology
and market developments.
Identify potential
cooperation
opportunities
(bilateral /
multilateral).
Launch joint initiatives,
such as application to public
funds (EU or national level).
Communicate through
publications and
participation in events.

6. 6
https://www.linkedin.com/com
pany/induction-motors-
platform/
Organised by

7. The Critical Raw Materials Act
7
Extraction Processing & Refining Recycling
3%  10% 10%  40% 15%
Organised by

8. Organised by
The case for rare earth-free designs
8
Extraction Processing & Refining Recycling
3%  10% 10%  40% 15%
Rare earths /
permanent
magnets
Copper
~ 0% ~ 0% ~ 0%
~ 25% ~ 100% ~ 50%
https://copperalliance.org/policy-focus/society-economy/circular-economy/stocks-flows/
CR Act
targets

9. 9
https://www.spglobal.com/marketintelligence/en/news-insights/latest-news-headlines/clean-energy-transition-to-fuel-
growth-for-china-s-rare-earths-sector-in-2022-68604096
Organised by

10. Organised by
10
www.refreedrive.eu
“Cradle-to-gate”
approach
Environmental comparison of two versions of a
200 kW EV motor: rare earth vs induction

11. Organised by
Innovations in design and modeling
11

12. 12
Agenda
• Why Multiphysics Simulations for Electrical Motors
• Optimization of Traction Induction Motors – Case
Study

13. Why Multi-physics
simulation for electric
motors

14. 14
Organised by

15. 15
Ansys Electric Machines Development Platform
Durability & NVH Simulation
Operational Performance Mapping
Concept Detailed Design & Verification
Thermal Management
Electromagnetic Analysis
System Integration
Integrated workflows enable complete Multiphysics evaluation of the electric machine at all stages in the development process
Process
Integration
and Design
Optimisation
Enabling
Multi-fidelity
modeling
Organised by

16. 16
Collaboration: Electric Drive Unit (EDU) Optimization
• In EDU development we are aiming for the highest drive cycle efficiency, lowest cost and smallest volume
• We need to make design decisions with regards to motor, inverter and gearbox that consider the whole EDU performance
• The electric motor design team needs to collaborate with many stakeholders, i.e. gearbox team, inverter team, system
engineering team, etc. to find the optimal motor design within EDU system
• The optimal individual components ≠ optimal overall system
Motor design team
Inverter design team
Gear design team
Systems & Integration team
System Targets:
Space envelope
System efficiency
Axle torque
System NVH
…
Component Targets:
Motor torque
Inverter current
Gear ratio
…
Target cascading
Component teams
‘To achieve efficiency
we need more space’
‘To achieve torque
We need more current’
‘Increased current
Reduces efficiency’
‘To achieve torque
We need higher speed’
‘Increased gear ratio
increases volume’
Specification changes
Organised by

17. 17
Multiphysics Data Generated from Ansys simulation
Organised by

18. Optimization of Traction
Induction Motors – Case
Study

19. ReFreeDrive Project Overview
19
• Development of the next-gen of
electric powertrains, focusing on
rare-earth free traction motors.
• Induction Motor (IM) technology
considered a potential candidate.
Copper rotor IM
High speed capability
Low cost manufacturing
Die-casted / Fabricated rotor
Hairpin winding technology
Low cost / loss materials
Design optimization
Rotor cooling
Organised by

20. Specifications
• Key Performance Indicators (KPIs)
20
• Reference: Tesla 60S copper rotor
induction motor.
Parameter Tesla 60S Target Unit
Specific power 3.3 ≥ 4.3 kW/kg
Power density - ≥ 8.0 kW/l
Specific torque 6.3 ≥ 8.2 Nm/kg
Torque density - ≥ 15.4 Nm/l
Peak efficiency 93 ≥ 96 %
Organised by

21. Design Workflow
21
• Motor-CAD & optiSLang coupled
for a comprehensive analysis:
• A meta-model approach is set up
in optiSLang to optimize the
machine.
Parameters Responses
• Objectives & Principles
Data-driven exploration of the design space
utilising multi-physics simulation
Organised by

22. Design Workflow
22
• A two-stage optimization process is
adopted to split the design space in
an effective way:
1. Electromagnetic design
2. Thermal design
• The machine’s performance are
calculated within its electrical and
thermal limits.
IM Analytical Magnetic Circuit
Lumped Parameter Thermal Network
Organised by

23. Design Workflow
23
• The efficiency over the WLTP3
drive cycle is evaluated using five
characteristic operating points.
• This clustering method allows to
reduce significantly the simulation
time in Motor-CAD.
• Efficiency over WLTP3 Drive Cycle
Organised by

24. Electromagnetic Design
• Machine topology:
‐ 4-pole, 36-slot, 50-bar
• Geometry:
‐ Stator outer diameter (mm) = 190
• Materials
‐ M235-35A steel (rotor & stator)
‐ CuAg0.04 (fabricated rotor cage)
‐ Cu-ETP (die-casted rotor cage)
• Stator winding:
‐ Turns / Phase = 12
‐ Packing factor (%) = 73
Preliminary Design Choices
24
Radial Geometry
Winding pattern
BH curves Specific Losses
Organised by

25. Electromagnetic Design
• Peak performance are met and the
efficiency over the WLTP3 drive cycle
is about 95.05% (motoring).
25
Organised by

26. Thermal Design
26
• Continuous performance (torque at
low speed, power at high speed)
requirements are met.
Organised by

27. Von Mises stress for inner rotor CR-IM, with (a) rotor core
M235-35A steel and (b) copper bar (units in Pa)
(a)
(b)
Von Mises stress for outer rotor CR-IM, with (a) rotor core
M235-35A steel and (b) copper bar (units in Pa)
(a)
(b)
Mechanical Design
27
Organised by

28. Conclusions on Optimized Induction Machine Design
• The design of a 200kW, 20krpm copper rotor induction motor for a traction
application has been presented.
• The machine was optimized electromagnetically, mechanically and thermally using
Ansys suite software.
• Solution with:
• Hairpin windings,
• Die-cast and fabricated copper rotor cage
• Series cooling fluid circuit (shaft, stator, inverter box)
28
Organised by

29. Organised by
Innovations in manufacturing
29

30. 30
Industry Standard vs. ZPR®
Status Comparison of Casting Technologies
Area [mm²] 262.5746
Porosity [%] 0.01
Tol (max) [%] 5.0000
Area [mm²] 381.366
Porosity [%] 10.1323
Tol (max) [%] 5.0000
Industry Standard Zero Porosity Rotor – ZPR®

31. Organised by
31
Industry Standard vs. ZPR®
Cu & Al Die-Cast Zero Porosity Rotors (ZPR®) for
induction motors
Porosity: 0.01 %
 Superior mechanical characteristics
due to high performance alloys
 Cutting edge quality compared to
industry standard
 Free of rare earths
 Economical high-volume production
due to casting process
 Maximum process stability
 Unique casting process (Laminar Squeeze Casting) leads to zero porosity
and maximum design flexibility
 Freedom in slot design
 High electrical conductivity
 Sustainable product (100% recyclable)
Benefits
Performance

32. 32
Industry Standard vs. ZPR®
Electrical Conductivity
Area [mm²] 262.5746
Porosity [%] 0.01
Tol (max) [%] 5.0000
Area [mm²] 381.366
Porosity [%] 10.1323
Tol (max) [%] 5.0000
Conductivity
AL 35 MS/m
Cu >57.5 MS/m
Conductivity
AL 25 - 28 MS/m
Cu < 50 MS/m
Industry Standard Zero Porosity Rotor – ZPR®
Organised by

33. Organised by
33
Industry Standard vs. ZPR®
Process Stability
Electric Motor Production
Production-
progress
Expected
Quality
Automotive understanding of Quality
Production-
progress
Expected
Quality
Industry Standard Zero Porosity Rotor – ZPR®

34. CONFIDENTIAL
34
200kW Induction Electric Motor -Product Features
Property of Denis Ferranti Meters Limited. No rights to use or disclose any information except for the Permitted
Purpose are granted in respect of this document
• High power 200kW (268 BHP) continuous
• High speed up to 20,000rpm
• Mass 60kg (40kg with mass optimisation)
• No rare earth materials
• Protections
• Speed sensor
• Winding temperature sensors
• Bearing temperature sensors
• Sealed unit, design for IP67
• No sparks or arcs, robust insulation
• Customisable interfaces
• Novel shaft cooling

35. CONFIDENTIAL
35
200kW Induction Electric Motor -Product Features
Property of Denis Ferranti Meters Limited. No rights to use or disclose any information except for the Permitted
Purpose are granted in respect of this document
• Motor-CAD analysis of the E-Mag aspect
highlighted the need for additional cooling
of the rotor.
• The cooling allows sustained high speed
and power operation of the rotor.
• Without cooling the heat would permeate
into the shaft and bearings.
• Forced cooling reduced the losses in the
rotor.

36. CONFIDENTIAL
36
200kW Induction Electric Motor –Shaft Cooling
Property of Denis Ferranti Meters Limited. No rights to use or disclose any information except for the Permitted
Purpose are granted in respect of this document
• Shaft cooling circuit can be in series or
parallel with the rest of the system.
• Through-shaft cooling allows the rotor to
achieve higher speed and more performance.
• Paired with custom seals it provides high
speed and high pressure cooling capability
for modern motor demands.

37. CONFIDENTIAL
37
200kW Induction Electric Motor –Shaft Cooling
Property of Denis Ferranti Meters Limited. No rights to use or disclose any information except for the Permitted
Purpose are granted in respect of this document

38. CONFIDENTIAL
38
200kW Induction Electric Motor –Shaft Cooling
Property of Denis Ferranti Meters Limited. No rights to use or disclose any information except for the Permitted
Purpose are granted in respect of this document
• Novel three piece shaft
• Through-cooling to cool rotor
• Integration with system cooling
• Allows high speed operation
• Integrated shear section for safety
• 110% torque rating
• Cost effective manufacturing processes

39. CONFIDENTIAL
39
Optimisation
Property of Denis Ferranti Meters Limited. No rights to use or disclose any information except for the Permitted
Purpose are granted in respect of this document
• The machine mass can be further optimised
• Reduce amount of back iron on stator
• Increase rotor lamination ID through use of
lightweight spacer
• Reduce stack length through use of higher
performance lamination material
• Increase power density through raising
temperature rating of insulation and use of active
cooling

40. Organised by
Innovations in materials
and applications
40

41. Organised by
Operational Boundaries – ‘High Speed’
 What is high speed?
 Machines above use ‘conventional’ high spec materials
m/s and rpm√kW
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
41

42. Electrical Steels
 Vast menu which includes
many recent developments
commercially available
 Losses reduced to lowest levels at
high frequencies with 0.1mm
6.5%SiFe and 0.05mm CoFe
 Several technical considerations to
take into account re low-loss SiFe,
CoFe, in light of kW/L , kW/kg
 New high strength
laminations have
over 200% more
strength compared to
normal laminations
42

43. Copper Alloys
 High Strength Cu Alloys which
retain mechanical strength
(400MPa) at elevated
temperatures (>400°C) developed,
ex. CuAl2O3
 High Strength, more
environmentally friendly Cu alloys
developed and commercially
available, ex. CuNiSiCr
 Research on future alloys :
>800MPa >70% IACS
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
43

44. Pushing the Boundaries – Methodology
Closely coupled sciences necessitate the development and use of multi-domain design environments
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
44
Organised by

45. Case Study (I) – Electrically Assisted Turbocharger
Electrical machine to recover
excess energy from exhaust
(generator mode) and reduce
turbo-lag (motor mode)
High level of integration in an
aggressive environment
rpm√kW =3x105
Machine Technology rpm√kW m/s
Solid rotor IM 1x106 400
Surface PM with sleeve
(no rotor laminations)
8x105 300
Switched reluctance 2.5x105 185
Laminated rotor IM 2.5x105 185
Power rating 10kW
Coolant temperature 110ºC
Power density 30kW/L
Speed 50-120 krpm
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
45
Organised by

46. Organised by
Case Study (I) – Electrically Assisted Turbocharger
SPM IM
Electrical Drive Cost (ratio) 1.6 1
Surface
Permanent
Magnet
SPM
Induction
Motor
IM
46

47. Case Study (I) – Electrically Assisted Turbocharger
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
 CuAl2O3 used for rotor cage. Low-loss
laminations.
 Machine tested on dynamometer up to
120krpm

48. Organised by
power rating 120kW
speed 50krpm
coolant temperature 110ºC
 rpm√kW typically
associated with PM
Machines
Existing PM machine
solution
Aim to push
boundaries of
laminated rotor
Induction Machine to
reduce drive cost
rpm√kW=6x105
Case Study (II) – High Horse Power Engine Waste Heat Recovery
8%
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
48

49. Organised by
120kW, 50krpm
rpm√kW 6x105
With novel materials, material characterisation and multi-domain design, power-
speed capability of laminated rotor IMs can match that typically associated with
Surface PM Machines, at a fraction of the cost (-45%)
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
49
Case Study (II) – High Horse Power Engine Waste Heat Recovery

50. Summary - Key points
 Exciting menu of new, better, materials
• electrical steels (ultra-thin, low losses, high Bsat, high strength)
• copper alloys (improved mechanical properties, good conductivity, high temperature
withstand)
 Importance of understanding the materials with appropriate
characterisation
 High temperature Cu alloys for very aggressive operational environments
(withstand capability, equalizing capability)
 Laminated rotor Induction Machines can be operated to higher power-speed
capabilities
Copyright © – The University of Nottingham. The use of content is only permitted with our express approval in writing.
50
Organised by

51. Organised by
Bob Austin, Denis Ferranti Group:
Bob.Austin@dfm-ltd.co.uk
Mircea Popescu, Ansys:
mircea.popescu@ansys.com
THANK YOU!
Fernando Nuño, ICA:
fernando.nuno@copperalliance.org
David Gerada, University of Nottingham
D.Gerada@nottingham.ac.uk