Rare earth free motor designs - ReFreeDrive project

13 May 2020 1
This project has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 770143
1
13 May 2020
Rare earth free e-drives
featuring low
manufacturing cost
European Copper Institute
IFP Energies Nouvelles
Webinar #1: Rare earth-free motor designs
for e-mobility
Motor Design Limited
University of Aquila

13 May 2020 2
ReFreeDrive Project Overview
• Horizon 2020 is the EU Framework Programme for Research and
Innovation with nearly €80 billion of funding available over 7 years (2014 to
2020).
• The general objective of Horizon 2020 is to help to build a society and an
economy based on knowledge and innovation, to provide funding for
research, development and innovation, and to contribute towards
sustainable growth and competitiveness in Europe.
• ReFreeDrive has been selected in the GV-04 call looking at societal
challenges for Smart, Green and Integrated Transport and receives H2020
funding
• Goal: avoid the use of rare earth magnets through the development of
a next generation of scalable electric drivetrains
EU Project in Horizon2020
ReFreeDrive project runtime: Oct 2017 – Sep 2020*
*(…will ask for extension)

13 May 2020 3
13 partners, 6 European countries
OEM
Validation
Project
coordination
Power
electronics
Vehicle
integration &
testing
Copper
Steel
Motor Design &
Manufacturing

13 May 2020 4
Why rare earth elements free solutions?
Environment & LCA
CostSupply risk
Market uncertainties

13 May 2020 5
Why rare earth elements free?
SUPPLY RISK
U.S. Department Of Energy - Critical materials strategy - December 2011
https://www.energy.gov/sites/prod/files/DOE_CMS2011_FINAL_Full.pdf

13 May 2020 6
COST
J.D. Widmer, et al., Electric vehicle traction motors without rare earth magnets, (2015),
https://www.sciencedirect.com/science/article/pii/S2214993715000032?via%3Dihub

13 May 2020 7
MARKET
UNCERTAINTIES
https://www.statista.com/statistics/450152/global-reo-neodymium-oxide-price-forecast/

13 May 2020 8
ENVIRONMENT
&
LCA
J.D. Widmer, et al., Electric vehicle traction motors without rare earth magnets, (2015),
https://www.sciencedirect.com/science/article/pii/S2214993715000032?via%3Dihub

13 May 2020 9
Meeting future copper demand: https://sustainablecopper.org/meeting-future-copper-demand/
The World Copper Factbook 2018: https://www.icsg.org/index.php/component/jdownloads/finish/170/2876
Dynamic Analysis of Global Copper Flows. https://pubs.acs.org/doi/10.1021/es400069b
US Geological Survey (USGS), 2019: https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/atoms/files/mcs-2019-coppe.pdf
Total resources
5000 Mtonnes
(250 years)
Reserves
830 Mtonnes
(40 years)
Annual production
21 Mtonnes
Deep sea deposits excluded
Primary route: mining (~70% of demand)
Identified resources
2100 Mtonnes
(100 years)
Secondary route: recycling (~30% of demand)
400 Mtonnes available
in the “urban mine”
(20 years)
Most of copper
alloying elements can
be recovered
Copper can be
recycled repeatedly
without downgrading
What about copper? Not a critical raw material
Diversified geographic
availability
9

13 May 2020 10
• The main aim of this project is to develop rare earth‐free traction
technologies
Project Objectives
INDUSTRIAL
FEASIBILITY
MASS
PRODUCTION
LOWER
COSTS
• Material selection
• Manufacturing
processes
• Design optimisation
• Scalability

13 May 2020 11
Project Technologies: we will design & manufacture
8 different e-motors for electrical powertrains
Induction machines
with copper rotor
Fabricated
Die Cast
Synchronous
reluctance machines
PMassisted
Without PM
75kW and 200kW
8
motors

13 May 2020 12
Target figures
30% INCREASE
SPECIFIC TORQUE
50% MOTOR
LOSSES REDUCTION
15% COST
REDUCTION
50% INCREASE
OF POWER DENSITY IN
POWER ELECTRONICS
Benchmark
Tesla S60

13 May 2020 13
• Accomplished the design optimization phase, we have
started to manufacture 8 physical prototypes of the
ReFreeDrive motors to be tested in 2020.
• All 8 prototypes (IM and SynRel, 75kw and 200kW) will be
extensively tested on motor test benches.
• At later stage, min two of the 75kW motors will also be
integrated into a LCV and tested in the vehicle under
driving cycle conditions at Perrugia circuit.
Outlook
Test Results in Q4 – 2020 (expected – tbc)

13 May 2020 14
Please visit:
www.refreedrive.eu
and
ElectricDrivetrainInnovationCluster
in LinkedIn

13 May 2020 15
Webinar series
1. Motor design
2. Power electronics
3. Manufacturing of prototypes
4. Test bench results
5. Techno-economic analysis
6. Life Cycle Assessment

16 Grant Agreement Nº 77014324 September 2018 Grant Agreement Nº 77014316 16 Grant Agreement Nº 77014316
Induction Motor Design
Motor Design Ltd.
Mircea Popescu, Nicolas Rivière

17 Grant Agreement Nº 77014324 September 2018 Grant Agreement Nº 77014317
Overview
1. Introduction
2. Specifications
3. Design Workflow
4. E-Mag Design
5. Thermal Design
6. Prototype
7. Conclusion
17

Introduction
18
• 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

Specifications
Boundary Conditions
19
• Target vehicle: Jaguar XJMY21
Requirement Value Unit
Peak torque @ Low speed 370 Nm
Peak power @ Base speed 200 kW
Cont. torque @ Low speed 152 Nm
Cont. power @ Max. speed 70 kW
Efficiency over WLTP3 cycle ≥ 94.5 %
Operating speed ≤ 20000 rpm
Stator cooling system Water Jacket -
Rotor cooling system Spiral
Coolant flow rate ≤ 10 l/min
Cooling fluid type EGW 50/50
Coolant temperature ≤ 90 °C
Pressure drop (jacket only) ≤ 20 kPa
Stator winding temperature ≤ 180 °C
Rotor cage temperature ≤ 180 °C
Inverter current ≤ 500 Arms
DC Link Voltage 650-720 Vdc
Package size envelope ≤ Φ250 x L325 mm
PerformancesCoolingPE

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 %

Design Workflow
21
• Motor-CAD & optiSLang
coupled for a comprehensive
analysis:
Fast and effective optimization
over the full machine’s operating
speed range with good accuracy.
Multi-physics analysis can be
carried out.
Rigorous and traceable
decisions for the design
parameters.
• A meta-model based 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

Design Workflow
Sensitivity Analysis1
3Optimization
4 Validation
Optimization Workflow in optiSLang
Meta-model of Optimal
Prognosis (MOP)2
22

Design Workflow
23
• 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.
• Each candidate solution takes
approx. 10minutes to be
computed in Motor-CAD
software.
Performance Evaluation in Motor-CAD
IM Analytical Magnetic Circuit
Lumped Parameter Thermal Network

Design Workflow
24
• 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

E-Mag 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
25
Radial GeometryWinding pattern
BH curves Specific Losses

E-Mag Design
Variable Parameters & Design Space
26
Parameter Range Unit
Active length [140; 175] mm
Mechanical airgap [0.8; 1.5] mm
Split ratio1 [0.5; 0.7] -
Slot depth ratio2 [0.3; 0.6] -
Slot width ratio3 [0.4; 0.7] -
Bar opening depth [0.5; 1.2] mm
Bar depth ratio4 [0.5; 2.0] -
Bottom bar width
ratio5
[0.2; 0.9] -
Top bar width ratio6 [0.3; 0.6] -
Bar Opening
Depth
Airgap
Bottom
Bar Width
Top Bar
Width
Bar
Depth
Slot
Depth
Stator
Back Iron
1 Stator Inner Diameter / Stator Outer Diameter
2 Slot Depth / (Slot Depth + Stator Back Iron Thickness)
3 Slot Width / (Average Slot Width + Stator Tooth Width)
4 Bar Depth / (Bar Depth + Rotor Back Iron Thickness)
5 Bottom Bar Width / (Bottom Bar Width + Rotor Tooth Width)
6 Top Bar Width / (Top Bar Width + Rotor Tooth Width)

E-Mag Design
• Peak performance are met and the
efficiency over the WLTP3 drive
cycle is about 95.05% (motoring).
Validation in Motor-CAD
27

Variable Parameters & Design Space
28
Parameter Range Unit
Housing thickness [12; 25] mm
WJ1 wall thickness [2; 5] mm
WJ channel width [5; 40] mm
SG2 channel height [2; 5] mm
SG wall thickness [1.5; 3] -
Flow rate ratio3 [0.1; 0.9] mm
1 Water Jacket
2 Spiral Groove
3 Shared between housing WJ and shaft SG
Housing thickness
WJ wall thickness
WJ channel width
SG channel
height
WJ wall
thickness
Thermal Design

Thermal Design
Validation in Motor-CAD
29
• Continuous performance (torque
at low speed, power at high
speed) requirements are met.

Prototype
Stator Assembly with Hairpin Winding
30

Prototype
Die-cast Copper Rotor and Shaft
Components
31

Prototype
Inverter Box and Motor Assembly
32

Conclusions
• 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 Motor-CAD and Ansys suite software.
• Solution with:
‒ Hairpin windings,
‒ Die-cast and fabricated copper rotor cage
‒ Series cooling fluid circuit (shaft, stator, inverter box)
• The optimized motor is currently being prototyped and will be tested later this year.
• A scaled version (75kW, 12krpm) will be then integrated on a vehicle powertrain for real
performance testing.
33

34 Grant Agreement Nº 77014324 September 2018 Grant Agreement Nº 77014334 34 Grant Agreement Nº 77014334
Thank you!

35
13 May 2020
Pure Synchronous Reluctance Motor
Design
University of L’Aquila
Andrea Credo, Giuseppe Fabri, Marco Villani

36
13 May 2020
Overview
• Introduction to the Pure Synchronous Reluctance Motor
(SynRel)
• Requirements
• Design Workflow
• Preliminary design
• Optimized design
• Results
• Prototype
• Conclusions

37
13 May 2020
Introduction to the SynRel
Radial rib
Tangential rib
Electrical steel
Flux barrier (usually air)
• Distributed stator windings
• Brushless AC control (Vector control)
• Magnetically salient rotor
View of the rotor core

38
13 May 2020
The SynRel could be a valid alternative for electric and hybrid
vehicles due to its simple and rugged construction. It has been
selected as Rare Earth Free motor solution for the next-gen of
electric powertrains.
Advantages:
• Very low losses in the
rotor also at high-speeds
• Less requirements for
cooling ("cold" rotor)
• Low inertia and mass
• Attractive from an economic
point of view
• Simple manufacturing
Drawbacks:
• Weak rotor structural
integrity at high-speeds
• Low flux-weakening region
for very high-speeds
• Low power factor
• Lower power-to-weight ratio
• Accurate design
• Complexity in control
Introduction to the SynRel

39
13 May 2020
Design Workflow
1)
Requirements
2) Preliminary
Designs
3) Performance
4) Choice of the
best candidate
5) Design
Refinement
6)
Electrom./Mech.
Optimization
7) Final Design
8) Performance
9) Prototyping

40
13 May 2020
Requirements
Parameter Unit Reference Goals
Motor Induction Motor SynRM
Cooling Liquid Liquid
Specific Peak Power (*) kW/kg 3.3 ≥ 4.3
Specific Peak Torque (*) Nm/kg 6.32 ≥ 8.2
Maximum speed rpm 14500 16000 ÷ 20000
Peak efficiency % 92 ≥ 96
Active parts weight kg 68 ≤ 47
Reference vehicle Tesla
Model S
(*) active parts only

41
13 May 2020
Requirements
Target vehicle: Jaguar XJMY21
Requirement Unit Value
Peak Power @ base speed kW ≥ 200
Continuous Power @ max speed kW ≥ 70
Peak efficiency % ≥ 96
DC Voltage V 650 ÷ 720
Inverter current Amax ≤ 700
Encumbrance (ODxL) mm 250x310
Cooling Liquid

42
13 May 2020
Preliminary Designs
4 poles 6 poles 8 poles
Fluid shaped rotors

43
13 May 2020
Comparison
Performance Unit Requir. 4 poles 6 poles 8 poles
Peak torque @ Base speed Nm 370 430 430 430
Peak power @ Base speed kW 200 260 280 270
Cont. power @ Max. speed kW 70 94 110 78
Maximum speed rpm ≤ 20000 18000 18000 18000
Peak Efficiency % ≥ 96.0 97.8 97.6 97.4
Maximum phase current A <700 700 700 700

44
13 May 2020
Design refinement
A new solution with radial ribs has been analyzed in
order to guarantee the structural integrity of the rotor at
high speed.
The tangential and radial ribs have been designed
through a Topology Optimization in order to minimize
the material in the rotor core.
A further design refinement has been carried out through
a Magneto-Structural Optimization.
A. Credo, G. Fabri, M. Villani and M. Popescu, "High Speed Synchronous Reluctance Motors for
Electric Vehicles: a Focus on Rotor Mechanical Design", IEEE International Electric Machines &
Drives Conference (IEMDC), 2019.

45
13 May 2020
New Rotor shape
The result of the process has
led to a new rotor layout with
asymmetric shape and
multiple ribs that connect the
segments to each other axially
and transversally.
This geometry is quite unusual
compared to those typically
reported in literature.View of the rotor core

46
13 May 2020
Final Design
Electrical steel M235-35A
Cross section of stator and rotor core

47
13 May 2020
Performance
Parameter Unit Reference Goals Final Design
Motor Induction Motor SynRel SynRel
Cooling Liquid Liquid Liquid
Specific Peak Power (*) kW/kg 3.3 ≥ 4.3 5.3
Specific Peak Torque Nm/kg 6.32 ≥ 8.2 8.4
Maximum speed rpm 14500 ≤ 20000 18000
Peak efficiency % 92 ≥ 96 96.4
Active parts weight kg 68 ≤ 47 46
Reference Tesla
Model S
(*) active parts only

48
13 May 2020
Performance
Performance Unit
Peak Power
5 sec.
Continuous Power
S1
Phase Current A 700 171
Phase Voltage V 416 416
Speed rpm 6000 18000
Average Torque Nm 380 35
Output Power kW 240 66
Total Losses W 23370 2860
Power Factor 0.61 0.56
Torque ripple (*) % 4 10
Hp: TCu= 160 °C VDC= 720
V
(*) Skewed rotor

49
13 May 2020
Efficiency maps
Torque vs
speed
The efficiency includes the “mechanical losses”.
Power vs
speed
ηη

50
13 May 2020
Mechanical analysis @18000 rpm
The ribs maintain enough mechanical integrity in the rotor
structure when rotational forces are applied at high speed (18000
rpm) satisfying the mechanical limits of the chosen electrical steel.
MPa

51
13 May 2020
Low Power SynRel 75kW
The lower power machine (75 kW) has been scaled from the
200 kW design only by changing the stator winding and the
stack length (→ same housing).
200 kW
max speed 18000 rpm
VDC=720V
75 kW
max 12000 rpm
VDC=350V
This scaled version will be integrated on a vehicle powertrain for performance
testing.

52
13 May 2020
Prototype manufacturing
Laser cut of the electrical
steel (courtesy of LCD)

53
13 May 2020
Prototyping

54
13 May 2020
Prototyping

55
13 May 2020
Prototyping
Integration of the Motor
with the Power
Electronics.
Liquid Cooled

56
13 May 2020
Conclusions
• The innovative proposed SynRel fully satisfies the requirements
and appears to be a good solution for automotive applications.
• The mechanical FE analysis has pointed out no critical stress at
high speed, with a reasonable deformation with respect to the
airgap dimension. The results confirm that the rotor structure is
able to withstand mechanical stress at high speeds.
• The lower power machine (75 kW) has been scaled from 200 kW
design only by changing the stator winding and the stack length.
• Since the 75 kW motor has a lower operating speed than the 200
kW motor, its design satisfies the mechanical limits, as well.
• The 75 kW and 200 kW SynRels will be tested later this year.

57
13 May 2020
Thank you for your attention
Andrea Credo: andrea.credo@graduate.univaq.it
Giuseppe Fabri: giuseppe.fabri@univaq.it
Marco Villani: marco.villani@univaq.it

58 Grant Agreement Nº 770143May 13th 2019 58 Grant Agreement Nº 77014313th May 2019
Design of a PM SynRel Motor
using ferrites
André Nasr – IFPEN
(andre.nasr@ifpen.fr)

Outline
• Comparison between NdFeB and Ferrite magnets
• Design of a 200 kW and a 75 kW PM SynRel Motor
using ferrites
– Requirements
– Stator and rotor design
– Electromagnetic performances

Comparison between NdFeB and Ferrite
magnets
Magnet charactersistics
NdFeB Ferrite
Most powerful magnets
• Br ~1.2 T
• Hcj ~ 2000 kA/m
Low magnetic properties
• Br ~ 0.4 T
• Hcj ~ 450 kA/m
Surface protection required No coating needed
High cost (volatile costs and
market uncertainty)
Inexpensive (~10 times less)
No particular problems with
manufacturing small magnets
High machining costs when
making small magnets

magnets
• In terms of electromagnetic performances, NdFeB motors are
always superior to ferrite motors.
How to reduce the gap ?
Reducing the gap
Motor
Technology Application

• Motor technology
– In PM assisted SynRel motors, 60 % of the total torque is reluctance
torque. Only 40 % of the torque is generated from magnets.
– Surface-Mounted PM motors is not a good technology for ferrite
magnets (100 % magnet torque).
magnets
Reducing the gap
PMaSynRel Motor SMPM Motor

magnets
• Application (motor size)
– Use more magnets per pole  Is there enough space for standard
ferrite magnets dimensions ?
Reducing the gap
NdFeB Motor Ferrite Motor

magnets
• Application (motor size)
– Use more magnets per pole  Is there enough space for standard
ferrite magnets dimensions ?
– High machining costs if very small magnets (no more price advantage)
Reducing the gap
Source : idealmagnetsolutions.com

magnets
• -15 % for maximum torque
• -17 % for peak power
• -32 % of torque at maximum
speed
NdFeB Motor Vs Ferrite Motor (B segment)

magnets
• -15 % for maximum torque
• -17 % for peak power
• -32 % of torque at maximum
speed
NdFeB Motor Vs Ferrite Motor (B segment)
-25 % of cost per N.m and per kW

Design of a 75 kW and a 200 kW PM SynRel
Motor using ferrites
Requirements
Parameter Unit 75 kW 200 kW
Specific Power kW/kg > 2.52 > 4.3
Specific Torque Nm/kg > 8.2 > 8.2
Active parts weight kg < 30 < 47
Maximum speed rpm 15000 - 18000
Peak efficiency % > 96 %

Designation Material
Lamination M235-35A
Magnet Ferrite
Copper wire G2 H class
• Machaon rotor design
• 5 pole pairs
• SPP = 2
• 7 ferrite magnets per pole
• AG = 0.6 mm
Stator and rotor design – 200 kW motor

• DC Voltage = 800 V
• Max current = 416 Arms
• Max torque = 405 N.m
• Peak Power = 226 kW (5000 rpm)
• Maximum efficiency = 96 %
• Weight = 46.1 kg (Active Part)
• Peak specific torque = 8.8 N.m/kg
(Active parts)
• Peak specific power = 4.9 kW/kg
(Active parts)
Electromagnetics performances – 200 kW motor

• Same housing
• Same rotor and stator geometry
• Same magnets
• Same mechanical parts
• 800 V  350 V
• 200 mm  75 mm
• 13 turns  14 turns
For the 75 kW motor design, scalability has been used
(same stator and rotor geometry as the 200 kW motor)
Stator and rotor design – 75 kW motor (Scalability)

• DC Voltage = 350 V
• Max current = 375 Arms
• Max torque = 148 N.m
• Peak Power = 88 kW (5300 rpm)
• Maximum efficiency = 95 %
• Weight = 19 kg (Active Part)
• Peak specific torque = 7.8 N.m/kg
(Active parts)
• Peak specific power = 4.6 kW/kg
(Active parts)
Electromagnetics performances – 75 kW motor
0 2 4 6 8 10
Speed [krpm]
20
40
60
80
100
120
140
MechanicalTorque[N.m]
Efficiency [%]
75
75
80
80
85
85
90
90
92
92
94
94
94
94
95
95
95
60
65
70
75
80
85
90
95

Prototypes
Source : Mavel
• Prototypes have been
manufactured by Mavel.
• Testing has already begun at
IFPEN facilities in France.

André NASR
andre.nasr@ifpen.fr

Rare earth free motor designs - ReFreeDrive project

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Similar a Rare earth free motor designs - ReFreeDrive project

Similar a Rare earth free motor designs - ReFreeDrive project (20)

Más de Leonardo ENERGY

Más de Leonardo ENERGY (20)

Último

Último (20)

Rare earth free motor designs - ReFreeDrive project