Automotive Engineering - March 2025 - 20

TECHNOLOGY REPORT
THERMAL MANAGEMENT
Enhancing E-motor design, thermal efficiency with advanced cooling
e-motor gearbox and inverter systems.
ATF can be applied to the stator in
several ways, including cooling the exterior
components and end windings.
Polymer circular stator oil guide rings,
which direct the ATF to the end-windings
from various angles, are also becoming
popular. These rings provide
design flexibility and optimized thermal
management.
Injection molding of stator rings alAutomotive
coolant lines, integrated exhaust pipes and ventilation tubes are among the most
complex and challenging components of modern vehicles.
Syensqo's coolant line polymers, such as Ryton
PPS, address the demanding needs of thermal
management in vehicles to maximize the
performance capabilities of coolant lines.
The acceleration of 800V permanent
magnet radial flux e-motors marks a
significant leap in the automotive industry.
This motor architecture offers
increased power density through
smaller, lighter designs that spin at
higher rpm. However, this advancement
brings with it the challenge of
efficient thermal management, especially
in dissipating heat from the magnet
wire within the stator.
Effective thermal management is
crucial for improving e-motor efficiency.
The primary heat sources are the copper-insulated
magnet wires, with heat
spreading to the slot liners. Engineers
have explored various cooling methods,
including traditional water jackets using
20 March 2025
ethylene glycol and water. However, the
trend is shifting towards using automatic
transmission fluid (ATF) or oilbased
fluids for direct cooling, driven
by its integration convenience with the
lows for unique cooling channels, facilitating
efficient heat removal from the
copper magnet wire and slot liners. This
method offers significant advantages
over traditional materials like die-cast
aluminum, including 25% weight savings,
faster manufacturing cycles and
reduced need for secondary operations
like machining or welding.
Selecting materials for stator oil
guide rings and cooling tubes involves
considering their performance under
high temperatures and exposure to ATF.
Syensqo, formerly known as Solvay
Specialty Polymers, produces Amodel
PPA and Ryton PPS, which could be
considered because of their mechanical
properties retention at temperatures
from 150 to 180°C (302 to 356°F),
chemical resistance, and dimensional
stability. These materials have been
used for over 15 years in gearbox components
and maintain performance under
harsh conditions.
Sustainability also plays a role in the
material decision criteria. Producers
work to reduce the global warming potential
(GWP) and carbon footprint, and
using renewable electricity while reducing
water usage and industrial waste
helps decrease this number.
In summary, thermal management
solutions for electric motors should
consider chemical resistance and dimensional
stability as part of their overall
performance. With the right material,
engineers can reduce weight, functionally
integrate multiple components and
improve durability.
Brian Baleno is head of Marketing
Automotive at Syensqo.
AUTOMOTIVE ENGINEERING
BOTH IMAGES: SYENSQO
Automotive Engineering - March 2025

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