Dr Yves Burkhardt - Valeo Siemens

Unrestricted © Valeo Siemens 2018 19.06.2018 Page 1Dr. Y. Burkhardt / VSeA R&D Mot&GBX
Challenges for future
e-motor materials
valeo-siemens.com

Two high-tech companies Valeo and Siemens joined forces to create a leading global
provider of innovative and cost-effective high-voltage components and systems for hybrid
and electric vehicles.
Inverter Electric Motor
On-board
Charger
Inverter & DC/DC
Full Drivetrain
Integration
DC/DC Converter On-board Charger
&DC/DC
Generator TechCenters Production
Innovative product portfolio More than 10 sites world wide
Valeo Siemens eAutomotive

Overview
1 Development trends for (H)EV motors
2 Electrification solutions to meet market trends
3 Challenges for e-motors
4 Challenges for insulation materials
5 Challenges for active materials
6 Conclusion

Multiple architectures for Hybrid & Electric Vehicles
P0/P1
P2
P3
P4
Belt Starter
Generator
Motor
Generator on
primary shaft
Motor
Generator on
secondary shaft
Motor Generator on rear axle
(with speed reducer /
transmission)
 Focus of Valeo Siemens
eAutomotive
 Focus of further
considerations in this
presentation

• Increase general power and torque
• Speed increase
• Increase of torque density
• Increase of DC voltage 400 V  800 V class (DC)
• Increase efficiency over driving cycle (e.g. WLTP)
• Shorter time to market
• Easy to integrate components
Development trends for (H)EV motors
Development trends result in new challenges for (H) EV motors
0
50
100
150
0
150
300
0 10000
Power[kW]
Torque[Nm]
Speed [rpm]
T_peak P_peak
0
50
100
150
0
150
300
0 10000
Power[kW]
Torque[Nm]
Speed [rpm]
T_peak P_peak
n_max n_max

Overview
6 Conclusion

Electric motors and integrated systems
Technical specifications
Peak power 26 - 300 kW
Peak torque up to 600 Nm
Rotation speed up to 18.000 rpm
Efficiency up to 96%
Power density up to 6 kW / kg
Features
 Various types of e-machines for axle drives, hybrid applications,
starter generator and range extender
 Easy customer specific adaption for motor designs up to
integrated e-Drive systems (motor + gearbox + inverter)

Overview
6 Conclusion

• Increase general power and torque:
• Higher (magnetic) forces:
• Magnetic forces in stator and rotor electrical steel
• Higher torque on shaft and package interface
• Higher torsion force in housing
• Higher losses
• Higher electromagnetic losses in active parts
• Higher ohmic losses in winding
• Stronger cooling needed
• Higher electrical power
• Higher currents in winding and connecting parts
Challenges for e-motors

• Speed increase
• Speed capabilities of bearings (esp. lubrication)
• Better rotor balancing needed
• Higher stiffness of rotor and housing
• Higher mechanical strength of rotor lamination
• Higher electric frequencies
 higher frequency dependant losses (e.g. from 10 kHz up to 40 kHz)
• Faster inverter switching
 steeper voltage slopes dV/dt (e.g. from 5 V / ns up to 50 V / ns)

• Increase of torque density
• Higher utilization of active parts:
• Higher flux density in electric steel
• Higher magnet flux
• Higher current density in windings
• Higher loss density in stator and rotor
• Direct winding cooling
• Rotor cooling
• Winding potting
• Higher temperature in motor
• Higher mechanical strength of rotor, stator, shaft and housing
Typically saturated
regions
Exemplary magnetic flux
density distribution
Exemplary temperature
distribution
End windings typically
hot spot at high torque

• Increase of DC voltage from 400 V to 800 V class
• Higher electric strength for slot insulation
• Higher electric strength for winding insulation, wire coating
• Increased clearances and creepage distances
Clearance
Creepage distance
Insulation
Potential 2
Potential 1 Distances increase > 60 %
Today: ~ 33 kV/mm
Higher voltage slopes and
over voltage peaks have to
be covered by wire
insulation

0 nmax
0
Mmax
speed n [rpm]
TorqueM[Nm]
0 nmax
0
Mmax
speed n [rpm]
TorqueM[Nm]
Thicker sheet / higher conductivity Thinner sheet / lower conductivity
Iron loss Iron loss
• Increase efficiency
• Losses in active parts:
• In constant torque range, stator
winding losses define thermal limitation
• In field weakening, iron losses define
thermal limitation
• At max. speed, rotor iron loss may define
thermal limitation for PSM
• Iron losses in active parts for different eddy loss coefficient
0 nmax
0
Mmax
speed n [rpm]
TorqueM[Nm]
• For increased speed / frequencies,
low eddy current losses in electric
sheet necessary
• Hysteresis loss less dominant
Stator winding losses
predominant
Iron losses
predominant
Rotor iron losses
relevant
Strong reduction of iron losses
Total loss

• Shorter time to market
• Platform approach
• Common parts which are easy to adapt
• Good long term material availability
• Stable long term material price
• Easy to integrate components
• Standardized interfaces
• Standardized sizes / motor diameters
• Integrated systems:
 Motor, inverter and transmission
in one component
+
Rotor
package
Housing
cooling
Stator core
types
Rotor
position
encoder
Ball
bearing
s
HV
connector
….
Shaft
Standard
parts
Building blocks Products

Overview
6 Conclusion

Derived from market needs results different needs for insulation material improvements:
• For slot insulation and wire coating:
Challenges for insulating material
Increased torque
density
Speed increase Steep dV/dt slopes
Voltage increase
Market demand Challenge for e-motor Challenge for material
High slot fill factor
Direct oil cooled
Increased operating temperature
Good thermal conductivity
DC voltage of 800 V Higher insulation strength (>33 kV/mm)
High demand for improvements in insulation materials
Thin material (< 0,2 mm)
Higher thermal class (> 200°C)
Higher th. conductivity (> 0,2 W/mK)
Withstand oil
Improved sliding ability

Overview
6 Conclusion

Derived from market needs result different needs for electrical steel / sheet improvements:
Challenges for electrical steel / sheet material
Increased torque
density
Speed increase
Higher saturation flux density
High mech. strength (Rm > 500 MPa)
High demand for improvements in electrical steel / sheet material
Higher utilization of e-sheet
Higher forces in e-sheet
Thin material in series (< 0,3 mm)
Lower specific loss at high frequency
Fatique data for e-steel
Higher electric frequencies
Higher rotor speed capabilities

Derived from market needs result different needs for permanent magnet improvements:
Challenges for permanent magnet material
Increased torque
density
Power and torque
increase
High demand for improvements in permanent magnet material
Reduced HRE content
Improved diffusion process
Quality standard
Higher energy density
Higher temperature class
Higher demag. strength (HCJ)
Higher magnet flux
Increased operating temperature
Higher utilization of active parts
Short time to market
Good long term material availability
Stable long term material price

Overview
6 Conclusion

 Strong increase in e-mobility market
 Proceeding e-mobility evokes further improvements in e-motor design
 Typical operation range is enlarged (higher speeds, higher torque density, …)
 To achieve improvements in e-motor design, improvements in motor materials are needed
 Close cooperation between motor suppliers and material suppliers beneficial
Conclusion

Thanks for the attention!

Dr Yves Burkhardt - Valeo Siemens

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