Workshop on high efficiency and low-cost drivetrains for electric vehicles

Workshop on high
efficiency and
low-cost
drivetrains for
electric vehicles
19 March 2019

2
INCREASE
SPECIFIC
TORQUE BY
30%
REDUCE
MOTOR
ENERGY
LOSSES BY 50%
INCREASE POWER
DENSITY IN POWER
ELECTRONICS BY 50%
Terms of the call
H2020-GV-2016-2017
Incremental reduction in total motor and
power electronics system costs through
optimised design for manufacture

3
13h15 Introduction
Michal Klima, European Commission
13:30 ModulED project
Project overview - Jonas Hemsen, IKA
Integration challenges - Patrick Debal, Punch
Powertrain
14:15 ReFreeDrive project
Project overview - Javier Romo, Cidaut
Motor designs and manufacturing technologies -
Multiple speakers
15:00 Coffee break
15:30 DRIVEMODE project
Project overview - Alexander Smirnov, VTT
Inverter development - Jens Müller, Semikron
Key innovations - Michael Burghardt, AVL
16:15 Wrap-up
Lucie Beaumel, EGVIA
16:30 Adjourn
Today’s agenda

4
#GV04
#H2020Energy
https://www.linkedin.com/company/
electric-drivetrain-innovation-cluster/

Jonas HEMSEN
Institute for Automotive
Engineering – RWTH Aachen
Patrick DEBAL
Punch Powertrain
19 March 2019

Context
1. Take up of e-mobility at larger scale in the
coming years
2. Need to have powertrain solutions ready for
mass-market within the next 5 years
3. Critical material is of concern for Europe:
reduce dependence on rare earth materials
4. Modular solutions allows addressing
different markets
5. Optimisation at component and vehicle level
6. Emerging power electronics devices
7. New manufacturing techniques for motor
production
20190319 ModulED 2

Context
1. Take up of e-mobility at larger scale in the
coming years
2. Need to have powertrain solutions ready for
mass-market within the next 5 years
3. Critical material is of concern for Europe:
reduce dependence on rare earth materials
4. Modular solutions allows addressing
different markets
5. Optimisation at component and vehicle level
6. Emerging power electronics devices
7. New manufacturing techniques for motor
production
20190319 ModulED 3

Partners and main contributions
• Coordinator, GaN based inverter, Injected
magnets
• Motor
• Regenerative braking
• Design and optimization of electrified
vehicle propulsion systems
• Simulation tool
• Cooling
• Transmission, vehicle integration
• Motor control
• Dissemination & Exploitation
20190319 ModulED 4

Concept & Specification
• New gen. of modular electric powertrain for BEV and HEV
• Full scale demonstration integrated in a BEV platform.
• C-segment (medium car) is the priority target
• Expected to be one the most sold vehicle segment in the near future
with market shares over 25 % in europe1
1: EUROPEAN VEHICLE MARKET STATISTICS - Pocketbook 2018/19, ICCT 2018
20190319 ModulED 6
Electric motor Inverter Transmission
Integrated Cooling System
Integrated Regenerative
Braking
Modular Powertrain
Assessmenttool

Specifications
• R&D on innovative components and technologies:
• A novel 6 phase, high-speed EM using less rare-earth magnets
• A novel inverter using latest generation of GaN semiconductors
• A transmission design with a two-stage speed reduction
• An regenerative braking with extended range of energy recuperation
• An integrated thermal system using phase change materials (PCM)
• R&D on assessment tool in order to be able to virtually design, simulate,
optimize and select the right components depending on vehicle
specifications
20190319 ModulED 7

Holistic Design Tool
20190319 ModulED 8

Motor
• High speed Permanent Magnet assisted Synchronous Reluctance
Motor – 6 phases
• Targeted: 150Nm but initial at 90Nm (current limit of inverter)
• Work carried out:
• Extensive electromagnetic and mechanical simulations for dozens of
configurations: efficiency map, phase current, and voltage, torque ripple,
winding configuration, mechanical stress
• Investigation: Hair-pin wire vs formed litz wire
20190319 ModulED 9
Overspeed: 27000 U/min

Motor
• Simulated efficiency of over 97%
20190319 ModulED 10

Injected magnets
• Idea: Replace sintered magnets in rotor by plastic bonded
magnets which are injection moulded into the rotor iron.
• Reduction of rare earth content compared to sintered magnet design
• Skip machining steps thus reducing waste
• More degrees of freedom for rotor geometry design
• Work done:
• Impact of pressure of injection, mechanical simulation
• Magnetising simulation
• Injection moulding tool for direct injection of
magnets in the rotor
20190319 ModulED 11

Inverter topology
• 6 phases of 2 windings each, powered by a full-bridge
• Series switches allow winding reconfiguration (series- or
independent connection of the windings)
• Isolation failure disconnected and motor running with reduced
number of phases
20190319 ModulED 12
Inverter topology (two windings of one phase represented)

GaN-based inverter
• Theoretical simulation of up to 99,6% of efficiency
at 22500rpm
• For 1 leg, put 2 GaN HEMT 650V/120A in parallel
20190319 ModulED 13
Wafer costs comparison for Ga2O3 and SiC wafers
(Green Car Congress)
Series Switch + Diode
Half Bridge

GaN-based inverter
• Unrivalled switching performance (switching time less than
10ns)
• 5 (2) times faster than Si (SiC)
• Low on-state resistance
• Frequency increase possible
• Compact device
• Cost GaN wafer <<< SiC wafer
• Work done:
• 2 GaN in parallel successfully operated in the project
• First prototypes tested
20190319 ModulED 14
Wafer costs comparison
for Ga2O3 and SiC wafers
(Green Car Congress)

Regenerative braking system
• Efficient and safe brake blending control of the high speed
drive module
• The integrated regenerative braking control:
• maximizes energy recuperation with dynamic brake blending of the
electric motor and brake system
• maintains vehicle drivability and stability
• considers constraints and restrictions from the electric powertrain
(battery, motor).
20190319 ModulED 15
• The high speed drive
module poses several
control challenges
because of fast dynamics
and large transmission
ratio

Transmission and cooling
• Choice of dual ratio (12.2; 21.7)
• Efficiency gain, cost saving (motor
and electronics)
• Better launch- and high speed
performance
• Increased losses, extra cost of
gear
• From more than 20 topologies,
the ones with best performance
at 1-gear and 2-gear ratios have
been identified
• Cooling for inverter, e-machine
and gearbox losses
20190319 ModulED 16

A Reference in EV Powertrains
2010 Nissan Leaf
• World's best-selling plug-in electric car
> 400k vehicles sold.
• Separate units for power delivery
module, inverter, motor and
transmission
• Separate packaging for different units
• Electric connections between units
“hidden”
Consequences:
• A lot of different housings, covers and
other parts
• Space taken in the vehicle
Power
delivery
module
Inverter
Motor Trans-
mission
20190319 ModulED - Electric Powertrain Integration 18

EV Powertrain Integration Drivers
• Compact unit, more space in motor bay available or use as
electric rear axle
• Simplification in vehicle assembly line, less connections to
make
• Cost reduction due to part integration/reduced part count and
less interfacing
• Improved efficiency
20190319 ModulED 19
W
L
H

Current Status of Development
20190319 ModulED 20

Integration of the motor and GaN inverter
20190319 ModulED 21
Sectional view (left) and 3D integration of the GaN based inverter (right)
MOTOR
INVERTER
TRANSMISSION

ModulED Powertrain
• Compact unit
L 513 x W 405 x H 275
• 2-speed
• Improved efficiency
• Gear configuration
• Bearing selection
• No oil pump
• Low back pressure integrated cooling
• Cost reduction:
• Reduced part count
• Less interfacing
• Further possibilities when GaN matures
• Will be demonstrated in a vehicle at the ModulED closing event
20190319 ModulED 22

Contacts and website
Coordinator
Charley Lanneluc Charley.LANNELUC@cea.fr
Presenters
Jonas Hemsen jonas.hemsen@ika.rwth-aachen.de
Patrick Debal Patrick.Debal@punchpowertrain.com
http://www.moduled-project.eu/
20190319 ModulED 23

Introduction to
ReFreeDrive
Project
Javier Romo
Cidaut Foundation
19 March 2019

2
General figures
Title: Rare earth free e-Drives featuring low cost manufacturing
Acronym: ReFreeDrive
Grant Agreement No: 770143
Topic: GV-04-2017
Project Total Costs: 5,999,131.25€
Total EU Contribution: 5,999,131.25€

3
Project partners and locations

4
Why rare earth elements free?
SUPPLY RISK COST
MARKET UNCERTAINTIES ENVIRONMENT & LCA

5
Project objectives
• The main aim of this project is to develop rare earth‐free traction
technologies
INDUSTRIAL
FEASIBILITY
MASS PRODUCTION LOWER COSTS

6
Target figures
30% INCREASE
SPECIFIC TORQUE
50% MOTOR
LOSSES
REDUCTION
15% COST
REDUCTION
50% INCREASE
OF POWER
DENSITY IN POWER
ELECTRONICS
Benchmark
Tesla S60

7
Machines to be designed,
prototyped and tested
PM assisted
Without PM
Induction machines with copper rotor
Fabricated
Die Cast
75kW 200kW
Synchronous reluctance machines

9
Our consortium partners
OEM Validation
Project
coordination
Power
electronics
Vehicle integration
& testing
Copper
Steel
Motor Design &
Manufacturing

11
ReFreeDrive in the Electric
Drivetrain Innovation Cluster

2
Copper Rotor Induction Motor
Requirement Unit Value
Peak power kW 200
Peak torque Nm 371
Maximum speed rpm 22000
Nominal torque Nm 152
Nominal power kW 70
Peak specific power kW/kg 4.3*
Peak specific torque Nm/kg 8.2*
Peak power density kW/l 8*
Efficiency % ≥ 94
Maximum DC bus voltage V 720
Maximum phase current Arms 500
Maximum dimensions mm 250 × 250 X 310
EV Traction Motor Specifications*
*) Jaguar XJMY21

3
Parameter Unit Value
Stator Slots - 36
Poles - 4
Rotor Bars - 50
Max speed rpm 20,000
Stator Slots - 36
Poles - 6
Rotor Bars - 50
Max speed rpm 15,000
Optimised Inner Rotor IM Optimised Outer Rotor IM
Hairpin Winding

4
Electric Steel
Inner Rotor
Property Unit M235-35A M290-50JKE NO30-15 NO20-HS
Magnetizing
Current@50Hz
Arms 162 160 169 168
Magnetizing
Current@400Hz
Arms 157 152 156 155
Maximum
Torque@50Hz/400Hz
N.m 370/350 370/350 370/350 370/350
Maximum Core Loss/
Total Loss
W 980/31500 1600/31500 750/31500 840/31500
Property Unit M235-35A M290-50JKE NO30-15 NO20-HS
Magnetizing
Current@50Hz
Arms 162 160 169 168
Magnetizing
Current@400Hz
Arms 157 152 156 155
Maximum
Torque@50Hz/400Hz
N.m 370/350 370/350 370/350 370/350
Maximum Core Loss/
Total Loss
W 980/31500 1600/31500 750/31500 840/31500
Electric Steel
Outer Rotor

5
Characteristic Unit
Bars and
end-rings
Filler
Soldered Welded
Material type - CuAg0.04 SAC305 Bercoweld K5
Tensile
strength
MPa 338 29.7 220
Shear
strength
MPa - 27@20°C 17@20°C
Electrical
resistivity
Ω.m (×10-6) 1.702 10.4 5 - 6.67
Electrical
conductivity
%IACS 101.3 16.6 25.8 - 34.4
Thermal
conductivity
W/(m.K) 388 58.7 120 - 145
Copper cage type Material Referred rotor resistance @
120°C [Ω]
Die-cast Cu ETP 0.01973
Fabricated/ soldered end-ring CuAg 0.04 0.0205
Fabricated/ welded end-ring CuAg 0.04 0.01902
Copper Rotor
Materials

6
Efficiency Map
Inner Rotor IM
Efficiency Map
Outer Rotor IM

7
Cooling systems:
• Fluid EGW 50/50
o Stator Water jacket
o Rotor hollow shaft cooling
• Fluid ATF
o Stator Water jacket
o Rotor and end-winding oil spray and splash
• Common cooling with PE block

2
Scalability approach: one
stator/rotor geometry for a large
range of output power applications
Use of low cost ferrites to replace
Neodymium based permanent
magnets for high power applications
Design of Permanent Magnet Assisted Synchronous
Reluctance Motors Without Rare earths
Main ReFreeDrive project challenges for PMa SynRel motor design
PMa SynRel motor technology is nowadays one of the best solutions to
reduce the rare earth content of electric traction motors
Rotor flux barriers design optimization
for improved EM performances and
high efficiency over a large region of
the torque/speed map
High maximum motor speed to
increase torque and power density

3
Design of Permanent Magnet Assisted Synchronous
Reluctance Motors Without Rare earths
200 kW Motor IFPEN Design – Main Results
Robust design
against demagnetization
High peak and
average efficiency
(up to 95.5%)
Torque envelop fulfilling
high performance
vehicle requirements
Optimized flux barriers design to
withstand mechanical stress constraints
at high speed (18000 rpm)
-Id=
-I Max

Marco Villani
University of L’Aquila
19 March 2019
Pure SynRel Motor
Design

2
Requirements and KPI
Requirement Unit Value
DC Voltage V 800
Base speed rpm 4800
Peak Power @ base speed (30 sec.) kW 200
Max speed rpm 18000
Rated Power @ max speed Nm 70
Cooling liquid
Specific Peak Power kW/kg > 4.3
Peak Power Density kW/lit > 8.0
Specific Peak Torque Nm /kg > 8.2
Peak Torque Density Nm/lit > 15.4
Maximum speed rpm 15000 ÷ 18000
Peak efficiency % > 96
Active parts weight kg < 47
Motor dimensions (ODxL) mm 250 x 310

3
Why the Pure Synchronous Reluctance motor ?
the rotor is potentially less expensive than both PM and
Induction machines due to cancelling cage, winding, and
magnets from its structure;
simple to manufacture;
no losses in the rotor (“cold rotor”);
no BEMF;
the control system is simpler than that of the field oriented IM
drives.
Drawbacks:
 low power factor (→ oversizing of the drive);
 torque ripple;
 mechanical stress on the rotor ribs at high speed.
accurate motor design !

4
Several solutions have been optimized and compared
 Rotor with symmetric flux barrers
 Rotor with asymmetric flux barriers
 Rotor cores without radial ribs (and adhesive resin in the flux barriers)
Pure SynRel motor design
2-pole
GO el_steel
4, 6, 8 pole
NGO el_steel

5
Final design – Performance and Efficiency maps
Peak Power Continuous
Power
Phase current Amax 700 231
Phase voltage Vmax 346 346
Speed rpm 4800 18000
Average_Torque Nm 400 37
Output Power kW 201 69.7
Joule losses W 22810 2480
Iron losses W 903 1350
Power factor 0.61 0.57
Torque ripple (*) % 12 15
(*) No-skewed rotor

6
WLTP_Class3
Tcu_Hotspot
Tcu_Avg
1800 sec
°C
91°C
Continuos Power
Thermal analysis
Peak Power

7
3D Fluid dynamic analysis (liquid-cooled motor)
Water jacket

8
Mechanical stress analysis @ high speed
Rotor core

9
Comments
The SynRel motor fully satisfies the imposed requirements with a
limited volume and good performances at rated and peak power.
The proposed design exhibits a higher T/A ratio, lower
temperature rise at full load, and a good mechanical robustness of
the rotor structure in high speed operations.
The Synchronous Reluctance motors can be considered a strong
competitor to the Induction and PM machines and allow good
efficiency, manufacturing simplicity, reliability, and price reduction.

IM Rotor
• Alloys
• Portfolio
• Production
Process/Costs
Aurubis R&D
Peter Walmsley
19 March 2019

2
Alloys – Working Temperature

3
Portfolio
Standard Dimensional Range

2
WHY HAIRPIN
Automotive Industry players look at the hairpin winding
Technology as a viable solution among:
HAIRPIN WINDING TECHNOLOGY
www. tecnomatic.it © 2019 Tecnomatic intellectual property.
www. tecnomatic.it © 2019 Tecnomatic intellectual property
• Suitability for mass production
• Vehicle traction highly demanding requirements

3
HAIRPIN WINDING MASS PRODUCTION SYSTEM
Twisting at
welding side
Slot liner
insertion
Hairpin
forming
Winding assembly &
Winding insertion
Welding
Epoxy and
coating

4
2) Facilitated heat dissipation:
3) Higher peak torque at low speed:
• Reduced DC resistance.
• Reduced airgaps in the slot
1) Higher slot filling factor*:
Pros
4) AC Additional losses caused by:
TM process enables improvements
of motor efficiency performance
VSFilling factor (~65%-75%) Filling factor (~35%-45%)
TECHNOLOGY COMPARISON
• Larger eddy currents due to larger wire cross section,
at high frequency
Cons
Pros
Pros 𝑭𝑭𝑭𝑭 ≈
𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵 𝑵𝑵 𝑵𝑵𝑵𝑵 𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝒂𝒂
𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼 𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼𝑼 ⋅ 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑺𝑺𝑺𝑺𝑺𝑺
*
• The teeth width of stator can be increase  reduction of the iron losses
• Compact winding heads
• (~65%-75%) compared to random wound winding (~35%-45%)

5
b). Increasing the numbers
of conductors in the slot
a) Choosing the proper
dimensions of the wire
N.4 flat wires per slot
N. 8 flat wires per slot
From 4 to 6 layers*
From 6 to 8 layers*
From 2 to 4 layers*
@ constant current
densityWinding Losses Vs N. of layers
Nonlinear dependence requires
proper winding design.
* Not generalizable results
IMPROVEMENTS REDUCING AC ADDITIONAL LOSSES
www. tecnomatic.it © 2019 Tecnomaticintellectual property

6
c) Improving transposition of conductors in the
slots in case of multiple paths winding
Improved
transposition
way 2way 1
IMPROVEMENTS REDUCING AC ADDITIONAL LOSSES
www. tecnomatic.it © 2019 Tecnomaticintellectual property www. tecnomatic.it © 2019 Tecnomaticintellectual property

7
TECNOMATIC is one of the players who are driving
the development of the hairpin technology, by
means of an effective IP portfolio, aimed at:
• Enhancing the motor performances.
• Protecting customers.
WORLDWIDE PATENT PORTFOLIO ON HAIRPIN TECHNOLOGY

Manufacturing of high performance rotors
Packaging
• Stacking and locking of single laminations
onto a madrel to form a lamination stack
Preaheating
• Preheating the lamiation stack to reach the
desired temperature
Casting
• Rotor casting
Removing
mandrel
• Removal of mandrel from cast rotor
Lamination delivery
Rotor
Casting
• Melting temperature
• Tool temperature
• Melt treatment
• Gating system
• Piston velocity
• Vent

3
Current Status of the Industry
Area
Porosity
Tol (max)
381.3662
10.1323
5.0000
[mm²]
[%]
[%]
Area
Porosity
Tol (max)
154.2760
8.5741
5.0000
[mm²]
[%]
[%]

4
Laminar Squeeze Casting - Results
Area
Porosity
Tol (max)
262.5746
0.0000
5.0000
[mm²]
[%]
[%]
Area
Porosity
Tol (max)
162.1874
0.000
5.0000
[mm²]
[%]
[%]

5
Laminar Squeeze Casting - Results
Side A
0%
Porosity
Side B
< 0,5%
Porosity

1Brussels 15/03/2019
Rina-CSM
contribution to
REFREEDRIVE
Project
Stefano Cicalè
Rina consulting-CSM
19 March 2019

2Brussels 15/03/2019 2
RINA/CSM is part of
the REFREEDRIVE
consortium due to
its experience in
non grain oriented
FeSi, the material
used as magnetic
core in rotating
electric machines
Rina CSM experoience in the
project

Rina Consulting
Centro Sviluppo Materiali
Introduction
CSM was started in 1963, as CORPORATE research centre of
FINSIDER (nationalized steelmaking corporation).
CSM experience on Electrical Steel started at beginning of 70’s
of last century, in cooperation with Finsider’s Terni Plant,
Nationalized steelmaking industry was privatized in 1994, so it
was CSM.
CSM nowadays is a fully private innovation center with
extensive experiences for the development of materials and
relative production processes. WITH A WIDE EXPERIENCE IN
ELECTRICAL STEEL. It is part of RINA Group (in its branch RINA-
CONSULTING), which is a global provider of classification,
certification, testing, inspection, training, advisory and
research services.

4Brussels 15/03/2019 4
RC- CSM Magnetic Measurement
Laboratory
EPSTEIN Frame (10-1000 Hz)
Single Sheet Tester (SST 500x500 mm - IEC 60404-3)
Small Single Sheet Tester (SST 30x280 mm – 10÷150
Hz)
Polarization range: J=0.1÷2.0 T

Characteristic curve measured after laser
cutting at 400 Hz

Core losses in Synchronous Reluctance motor 6pole-
54slots 200kW (peak)
W W
M253-35A NO 30 NO 20

%
Percentage of Power Utilization

8Brussels 15/03/2019 8
Gain of overall efficiency of 6pole-54slots
200kW reluctance motor realized with NO30
and NO20 respect M235
Δη
%
NO 30 NO 20

Selected material
The material which was considered by
the consortium as the best compromise
beetween characteristics and cost was
M235-35A, which was selected for the
realization of the prototypes

10Brussels 15/03/2019
Thank you very
much
10

DRIVEMODE Project
Integrated Modular
Distributed Drivetrain
for Electric & Hybrid
Vehicles
Alexander Smirnov
VTT
19 March 2019

Consortium
Brussels 19 Mar
2019
• HORIZON 2020
• 3 year project
• 2017 – 2020
• 12 Partners
• 6 countries
• Budget ~9,5 mil
€
Finland:
Danfoss Editron
VTT
Germany:
AVL
SEMIKRON
Technical University Ilmenau
Sweden:
BorgWarner
Chalmers University
NEVS
Italy:
ICONS
S.C.I.R.E
Austria:
Thien eDrives
Slovenia:
University of Ljubljana

Objectives
Developing efficient and cost-effective drivetrain
modules for distributed drive concept
Brussels
Integrated module
Distributed drive
Mass production
I
M G
19 Mar
2019

Motivation
19 Mar
2019
Brussels
Integrated module
• Simplifies installation for OEM
• Reduces material usage
• Optimal synergy between
components
• Open possibilities for SME
Distributed drivetrain
• Single design for large variety of
vehicles
• More flexibility in layout
• Better control and more
functionality

Target Values
19 Mar
2019
Brussels
50% increase in
e-motor speed
30% increase in
specific torque & power
50% reduction
in losses
800V voltage for material
reduction and fast
charging

Project Structure
WP5 Cooling circuit
WP1 Coordination
WP3 Motor
WP4 Converter
WP6 Gearbox
WP7
Assembly, testing, demostration
WP2
System design
WP8 Dissemination
and exploitation
TechnicalManagementTeam
Project Coordination Committee
Brussels 19 Mar
2019

Task Distribution
Brussels 19 Mar
2019
Cooling CircuitInverter
Gearbox
IDM
Motor

Project Roadmap
July 2018
November2017
February 2019
Brussels 19 Mar
2019

Project Roadmap
October2020
March 2020
Assembly
8
Component testing
7
On-board testing
9
September 2019
Brussels 19 Mar
2019

Design Approach
Brussels 19 Mar
2019
Reflection
&
evaluationRequirements
&
specifications

Design Approach
• As an outcome of design procedure a
number of concepts were generated
• The final decision tree has 6 possible
variations
• The IDM has been selected
according to the score in the decision
matrix
Brussels 19 Mar
2019
2
1
3
4
5
6
14:1
16:1
Concept 1
Concept 4
Concept 4
AS 1b
PM 2a
PM 2a
AS 1b
PM 2a
AS 1b
Gear ratio Gearbox E-motor IDM

Outcomes
Brussels 19 Mar
2019
SiC Inverter
20kHz switching
140 A rms current
High-speed permanent magnet
synchronous machine
75kW, 100Nm, >20,000 rpm
Three stage high-speed gearbox
97% efficiency around nominal points

Thank you very
much
15
Alexander.Smirnov@vtt.fi

This project has received funding from the European Union's Horizon 2020 research
and innovation programme under grant agreement No 769989
WP4 - Converter
Dr. Jens Müller - SEMIKRON

WP2 converter specifications
Brussels 19 Mar 2019
Power
Electronics
Cooling
System
12 V DC
Bus
VCU
Electrical
Machine
HV
battery
bus
65°C at 10l/min
nom. Voltage
800 V
Converter
optimization
Max phase
current 140 A
• Half bridge topology for
simple control
• cost reduction by thermal
optimization aiming for a
smaller total chip area
 Only 3 parallel SiC
MOSFET (1200V) per
phase

Thermal optimization I
• MOSFET and packaging technology
require max temperature: of 150°C
• Increased distance of MOSFETs
reduces temperature
 allows higher currents
142°C
129°C
105 A
105 A

Thermal optimization II
Final design with:
• Optimzed MOSFET distance, SiN
ceramic substrate and high
performance thermal paste
• Al heat sink with Cu plate as well as
pin fins beneath hot spots
uniform temperature < 150°C at 140A
with 3 instead of 4 SiC MOSFET Al
Cu
Capacitor
cooling

Power density
• DRIVEMODE converter
Inverter type/
Parameter
series product DRIVEMODE
Chip technology 600 V Si IGBT 1200 V SiC MOSFET
DC-Link voltage [V] 350 Up to 920
Switching frequency
[kHz]
6 20
Volume [l] 12 2,8
Output power [kW]
(cosϕ = 0.85)
109 117
detailed power loss
investigation during
testing of demonstrator
9 kW/l 41 kW/l  +350%
power density

design for manufacture
Inverter cost reduction by use of
• Standardized internal screw layout
• Direct AC motor interface (no cables)
• VDA Standard connectors for cooling
• Fast mounting HV battery connector (no tools
required)
• Reduced component count for control and gate
drive (improved FIT rate)
Outlook: Plastic interface between motor and
converter possible?

Jens Müller, jens.Mueller@semikron.com

E-Machine
Michael Burghardt
AVL
19th March 2019

2
Content
Design challenges of the electrical machine:
• Performance requirements
• Major design issues due to high-speed application
• Choice of technology: PMSM vs. IM
Simulation results for the final design:
• Torque-Speed- and Power-Speed-Characteristics
• Loss analysis
• Thermal analysis
• Mechanical analysis
Conclusion

3
Design challenges of the electrical
machine:
Performance requirements
Unit Requirement Comment
E-Motor max.
fundamental
frequency
Hz 1400 Depending on maximum speed
and pole number of E-Motor
Inverter max.
PWM frequency
kHz 20
Max. Line2Line
voltage
Vrms 424 at minimal DC link voltage (600
VDC)
485 at minimal DC link voltage for
full performance (720 VDC)
509 at nominal DC link voltage (720
VDC)
562 at maximal DC link voltage
(796 VDC)
E-Motor phase
current,
maximum
Arms 140 For 30 sec
E-Motor phase
current.
continuous
Arms 70
dV/dt kV/
µs
12
(40 optional)
Voltage switching speed,
insulation quality have to
withstand
(with higher frequency losses
in inverter can be reduced)
Unit Requirem
ent
Comment
Max. speed for
full
performance
rpm 20170
(nmax)
Full operation, no deformations
allowed, failure not allowed
Spinning speed rpm (nmax ∙
1.2)
No permanent deformations
and influence on performance
allowed between max. speed
and spinning speed
Burst speed rpm (nmax ∙
1.4)
Permanent deformation
possible, but failure not allowed
between spinning speed and
burst speed
Opera-
ting
points
E-Motor
speed
(rpm)
E-Motor
torque
(Nm)
Opera-
ting
points
E-Motor
speed
(rpm)
E-Motor
torque
(Nm)
1 762 5 6 6058 11
2 2402 12 7 6237 21
3 2768 24 8 9525 6
4 3279 36 9 10529 14
5 5570 4 10 13320 21

4
7427; 45
7036; 95
9400; 71
13500; 36,64
20170; 16,60
0
10
20
30
40
50
60
70
80
90
100
0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000
ShaftTorque[Nm]
Shaft Speed [rpm]
Performance Requirements
cont. torque req. peak torque req. (shall) peak torque req. (should) peak torque req. (may)
machine:

5
machine:
7427; 35000
13500; 51800
60900
9400; 70000
0
10000
20000
30000
40000
50000
60000
70000
80000
0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000
ShaftPower[W]
Shaft Speed [rpm]
Performance Requirements
cont. power req. peak power req. (should) peak power req. (may)
peak power mean peak power req. (shall)

6
machine:
Major design issues due to high-speed application
To high-speed traction E-Motors additional requirements occur in the design process and have to be consider
in all phases of the project.
High Speed
• Sustainable materials on all parts to withstand the mechanical forces
High driving frequencies
• Regarding to the planed DC link of 800V and SiC switch Technology, an additional challenge will occur.
• Partial discharge of the E-Motor winding insulation
• Over time completely breakthrough of insulation
• Electrical potential of the rotor
High frequency losses
• Increase of iron and copper losses
• Rotor and stator must be produced with high permeability and low electromagnetic losses
• Iron lamination must be chosen as thin as possible but still within justified industrial production range
• Winding must counteract the increased copper losses due to slot magnetic flux leakage

7
Design challenges of the
electrical machine:
Choice of technology: PMSM vs. IM
In the DRIVEMODE project the WP3 evaluated two technologies
• Induction motor (IM), squirrel cage asynchronous motor
• Efficiency improve at high speed and partial load
• Lower efficiency because of the rotor losses
• Efficiency increases at high speed and partial load
• Permanent magnet synchronous machine (PMSM)
• Best peak efficiency
• In field weakening mode, lower efficiency
After comparing IM and PMSM from various sides the WP3 team decided to improve the
topology and enhance the design of the PMSM to reach the goal.

8
Content
• Loss analysis
Conclusion

9
Simulation results for the
final design
Torque-Speed- and Power-Speed-Characteristics
Continuous Operation Time: no Limit
Current: 140A
Voltage: 720Vmin
DCDC Link: 800Vmax Batt
Peak Operation Time: 60sek
0
10000
20000
30000
40000
50000
60000
70000
80000
0 5000 10000 15000 20000 25000
Power[W]
Speed [rpm]
Mechanical peak power

10
final design
0,00
20,00
40,00
60,00
80,00
100,00
120,00
0 5000 10000 15000 20000 25000
Torque[Nm]
Speed [rpm]
Shaft peak torque
Continuous Operation Time: no Limit
Current:140A
Voltage: 720Vmin
DCDC Link:800Vmax Batt
Peak Operation Time: 60sek

11
final design
Loss analysis
Efficiency map at
Winding temp 20°C
PM Temp 20°C

12
final design
Loss analysis
Efficiency map at
Winding temp 150°C
PM Temp 120°C

13
final design
Thermal analysis
• Thermal analysis of relevant operation points for
continuous and peak operation
• Comparison of two different cooling jacket designs
regarding their cooling efficiency. The used coolant is
water/glycol 50%/50%.
• Consideration of the operation points at corner and
maximum speed for maximum continuous torque and
peak torque at defined cooling conditions
• Check of permissible limit component temperatures
for:
• Winding max. 180°C (insulation class H)
• Magnet  max. 160°C (N42UH material)
• The transient considerations for peak operation are
performed with an initial machine temperature of 40 °C
(cold start) and 100 °C (warmed up machine).
Item Value
CONTINUOUS operation @:
• corner speed
• max. continuous torque
7000 rpm / 54,8 Nm
PEAK operation @:
• corner speed
• peak torque
7000 rpm / 108,9 Nm
CONTINUOUS / PEAK operation @:
• max. speed
• max. continuous/peak torque
20000 rpm / 25,7 Nm
Coolant inlet temperature 65 °C
Volume flow rate 10 l/min
Ambient temperature 40 °C
Spiral
jacket
Axial
parallel
jacket
Channel height: 5mm
Channel width: 30mm
Flow paths: 1 (serial)
Channel height: 5mm
Channel width: 30mm
Flow paths: 17 (parallel)

14
final design
Thermal analysis
Operation point
Jacket Cooling – Spiral Jacket Cooling – Axial parallel
Steady state
temperature
[°C]
Continuous
operation
possible ?
Limited
operating
time
60s PEAK
operation
possible ?
Steady state
temperature
[°C]
Continuous
operation
possible ?
Limited
operating
time
60s PEAK
operation
possible ?
CONTINUOUS 1
7000 rpm / 54,8 Nm
Total losses: 1316 W
Winding
119,7
Yes /
Winding
131,1
Yes /
Magnet
119,5
Magnet
130,7
PEAK2
7000 rpm / 108,9 Nm
Total losses: 3894 W
Winding
246,1
Yes
Winding
279,9
Yes
Magnet
214,2
Magnet
247,6
CONTINUOUS / PEAK 3
20000 rpm / 25,7 Nm
Total losses: 2658W
Winding
148,3
No 19,1 min Yes
Winding
172,4
No 16,6 Yes
Magnet
190,1
Magnet
213,9
Schematic
Example
 The resulting limited operation times for continuous operation are
based on an initial e-machine temperature of 40°C (maximum ambient
temperature).

15
final design
Thermal analysis
No. Remark
1 The spiral water jacket shows a better cooling behavior than the axial parallel water jacket.
Although the channel cross section is equal in both cases the flow velocity inside the spiral jacket is
much higher as the axial jacket includes 17 parallel flow paths.
2 The considered continuous operation point at corner speed shows an uncritical thermal behavior
with a sufficient thermal reserve for both components, the magnets and the winding.
3 The considered peak operation points at corner speed and at maximum speed show a sufficient
thermal behavior after 60s for both initial e-machine temperature levels (40°C  ambient
temperature and 100°C  warmed up e-machine).
4 The considered continuous operation point at maximum speed can just be hold for a limited time.
It has to be checked if the available operation time is sufficient for the usage in the real application.
This issue is based on the high iron losses (eddy current losses) inside the electric sheet which
occur at high rotational speeds.
For a better assessment a thermal duty cycle analysis of the machine is suggested.

16
final design
Mechanical analysis

17
final design
Mechanical analysis
BackTop

18
final design
Mechanical analysis

19
final design
Mechanical analysis
Item Unit REQ Value
Housing outer diameter mm 215 (260) 204/220
Housing total length mm 180 (270) 220
Stator outer diameter mm 174
Stack length mm 120
Total stator length mm 207
Stator copper weight kg ̴6
Stator iron weight kg 9.2
Rotor copper weight kg -
Rotor iron weight kg 5.4
Magnet weight (total) kg 0.76
Total active weight kg 21.4
Rotor inertia kg m² 0.01
Bore volume *** l 0.98
Housing weight incl. Cooling jacket kg ~5.4
Total weight e-motor kg 20 (52) ~30
Part Material
Stator stack NO20-1200
Stator Winding Copper
Rotor stack NO20-1200
Magnets BMN-42UH/ST
Balancing Ring Stainless Steel V2A
Shaft 42CrMo4
Bearings Stainless Steel V2A
Bearing Shields EN-AW-6082
Cooling Jacket EN-AW-6082
Housing EN-AW-6082
Resolver cap EN-AW-6082

20
final design
Mechanical analysis / Bearing concept
To keep cost and complexity low it was decided to forego a
cumbersome design to oil grease the non drive end bearing and to try
it with a sealed bearing instead.
• Only three bearings for motor and pinion gear shaft in total
• Connection of motor pinion gear shaft via spline
• Spine connection is sealed with O-ring and is grease
lubricated to keep wear low
• Axial and radial forces from pinion gear are supported by bearings
in gearbox
• Oil lubricated bearings
• Motor bearing is grease lubricated and only has to take internal
loads from eccentricity and magnetic reluctance forces

21
final design
Mechanical analysis
Step voltage surges from inverter switching can
introduce bearing currents which lead to wear and
finally failure of the bearing.
A possibility to reduce the risk of bearing currents is
the grounding of the motor shaft via some sort of
conductive connectors
• To reduce the risk of unwanted bearing currents
the option for one or two grounding rings for the
rotor shaft is provided
• E-motor non drive end side
• E-motor drive end side
• The necessity of the grounding rings will be
evaluated on the test bench
• Ground rings from AEGIS are used for this purpose

22
final design
Mechanical analysis
• Contact pressure in press fit connection reduces
with increased speed and temperature
• Contact pressure after manufacturing has to be
chosen to guarantee torque transmission over
whole speed and temperature range
Press fit
• Traction drives have to be operated in
subcritical speed range to avoid resonance
due to eccentricity
• Simulation leads to resonance frequencies
high above operation range
Critical Speed resonance
Rotor sheet mech. strength

23
Content
• Loss analysis
Conclusion

24
Conclusion
Mass and performance at 7000 [rpm] at permanent magnet temperature 90 0C and UDC=720V.
1,40
1,10
1,60
2,50
1,70
1,10
3,80
4,27
0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50
2012 LEAF (80KW)
2011 SONATA (30KW)
2010 PRIUS (60KW)
2008 LEXUS (110KW)
2007 CAMRY (70KW)
2004 PRIUS (50KW)
2016 BMW (125KW)
DRIVEMODE
Power density (kW/ kg)
Manufacturer
Marked comparison

25
Conclusion
0,00
20,00
40,00
60,00
80,00
100,00
120,00
0 5000 10000 15000 20000 25000
Torque[Nm]
Speed [rpm]
Shaft peak torque
Drivemode
Specification:
Max Torque
Cont. Torque

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