Automotive Engineering - March 2024 - 18

EV energy
management
POWERS-UP
Batteries get all the attention,
but power-electronics developers
lean into the cost equation as EV
affordability concerns persist.
by Sebastian Blanco
F
uture electric vehicles will be more efficient,
more powerful and will be able to hold more
energy in their batteries than today's EVs. Those
big " mores " require countless small improvements
beyond the headline component - batteries.
One of the richest target areas is power-electronics
technology and components used throughout the EV
ecosystem. A new generation of power electronics will
be found in tomorrow's EVs, charging stations and
related infrastructure components.
Burak Ozpineci has a front-row seat to how better
power electronics revolutionize the automotive industry.
Now the section head of the Vehicle and Mobility
Systems Research Section at Oak Ridge National
Laboratory, Ozpineci has seen how technologies such
as silicon insulated gate bipolar transistors (IGBT) were
fundamental to both the GM EV1 and the Toyota Prius.
" [Those vehicles] happened because of the silicon
IGBT, " Ozpineci told SAE Media. " Then people used
IGBTs because IGBTs became a household name for
power electronics in many applications. Then, in the
early 2000s, we started looking at silicon carbide, and
in the early 2010s, everybody started looking into silicon
carbide devices. "
Tesla famously used a silicon carbide (SiC) drivetrain
inverter in the Model 3 when it came out in 2017, and
Ozpineci said it's expected in the industry that, after
2030, most EVs will use SiC devices. So-called widebandgap
materials, specifically SiC and gallium nitride
(GaN) offer marked efficiency improvements compared
with silicon semiconductors.
18 March 2024
A chief power-electronics
component, the motor
inverter, is integrated with
the traction motor and gearbox
in Schaeffler's " 3-in-1 " e-axle.
" When we first started in 2001, there were just a few devices available, "
Ozpineci said. " They were brand new, they were expensive.
But with the introduction of the silicon-carbide MOSFET, maybe
close to 10 years ago, people started looking at those devices more
seriously. " The race to improve continues. Tesla announced in 2023
that it is developing a SiC inverter that will use 75% fewer siliconcarbide
(SiC) MOSFETs.
SiC is today's state-of-the-art
Vishnu Medisetty, director of power electronics for Bosch in North
America, confirms that SiC devices are the mainstay of the company's
power-electronics portfolio. Bosch began developing SiC semiconductors
in 2001 and the first MOSFET prototype was available in
2011, he said in an interview with SAE Media, adding that the trajectory
continues strongly upward.
" We are already on our second generation [of SiC], " Medisetty acknowledged.
" We are working towards our third generation and there
are generational improvements in the efficiency of the devices. So
the device efficiency improves - but also, there's a huge cost driver
behind EV applications. What we look at is trying to reduce the cost
of the power-electronic device, be it a charger converter or be it an
inverter that is driving the motor. We try to reduce the size of the die,
the chip, extract more current out of it, need less cooling for it. "
While Tesla hasn't specified just how it will reduce SiC devices in
future powertrains, the industry also is working on replacing SiC
AUTOMOTIVE ENGINEERING
SCHAEFFLER
Automotive Engineering - March 2024

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