Magnetics Business & Technology - January/February 2023 - 12

FEATURE ARTICLE
Innovations by hofer powertrain: New Motor Winding Technology and GaN Power Electronics
Tests with VisIC
fers scope for automation, reports the company. The new winding
technology is suitable for electric and hybrid powertrains from
passenger cars and formula-class sports vehicles to trucks and
commercial vehicles. Besides technology licenses, hofer powertrain
offers ready-made solutions and supports its customers
as a development and manufacturing partner from conception to
production and beyond.
hofer powertrain of Germany has developed a new magnet wire
winding technology for the motors in e-powertrains to make them
smaller and lighter yet just as powerful as with previous techniques.
On the electronics side, it is developing new inverter systems
based on Gallium Nitride semiconductors from VisIC Technologies
of Israel.
The new patented Form Litz Wire winding technology provides the
same high performance as its predecessors, both pull-in and hairpin
windings, yet brings a significant cost reduction of the complete
powertrain system, the company says. The technology consists of
parallel wires packed into a highly compact form, ensuring a high
filling factor. It enables effective integration with various cooling
systems, thus reducing energy losses to a minimum. Numerous
tests confirm that electric motor energy losses are reduced by up
to 25%, positively affecting the entire system and resulting in continuous
high output for a more extended driving range.
Combining the best of two winding technologies (pull-in and hairpin)
in one innovative Litz wire system for minimal power losses. New
heights in efficiency and a significant increase of power density for a
wide range of motor types are reached with the new Litz wire technology.
The potentials and benefits of today's state-of-the-art hairpin
winding, and the commonly used pull-in winding system have been
combined in a new wire winding. The smaller wires from the pull-in
winding have been compressed to achieve the same filling factor and
copper density as the hairpins and at the same time allow the highfrequency
behavior of the standard pull-in wiring, therefore pushing
the boundaries for high-speed electric drive units.
Cross-section of Form Litz Wire winding technology compared with
Pull-In and Hairpin windings
To develop its innovative powertrain solutions, hofer has focused
on reducing materials in its stator, rotor and housing designs so
that the quantity of copper, iron and rare earth metals in its permanent
synchronous motor is substantially lower.
Form Litz Wire is also cost-efficient. In the near-term, manufacturing
can use conventional hairpin winding tools to achieve
production with minimal industrialization effort. In addition, the
design lends itself to consistent production quality control and ofAlso,
hofer says it is evaluating the
integration into its power electronics
the latest Gallium Nitride chip technology
D3GaN (Direct DriveD-Mode),
provided by VisIC Technologies Ltd.,
to achieve new efficiency and power
density. Gallium Nitride semiconductors
are key to efficiency improvements,
says hofer, increasing the
driving range and lifetime of electrified
vehicles. hofer powertrain and VisIC
aim to develop Gallium Nitride-based
power inverters for electric vehicles to
support 800V battery systems.
" We are proud to have reached the
next step in developing efficient GaNbased,
high-frequency inverters for
800V automotive applications, " says
Lukasz Roslaniec, Electronics Expert at hofer. Based on the guiding
principle " develop fast and learn fast, " the company focuses
on reality-based development secured by successful customer
" Achieving multiple efficiency
and sustainability
goals in powertrains with
our technology makes
us particularly proud, "
Johann Paul Hofer, CEO.
12 Magnetics Business & Technology * January/February 2023
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Magnetics Business & Technology - January/February 2023

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