Automotive Engineering - August 2021 - 6

TECHNOLOGY REPORT
Inside the scalable EDM
The four dedicated BEV platforms, optimized around width
and length, " will unlock new facets of our brands, taking their
efficiency and performances to the next level, " promised chief
engineering officer Harald Wester. The three STLA unibody
platforms (pronounced " stella " ) are sized small (A/B segment),
medium (C), and large (C/D and D; 4.7 to 5.4 m long).
STLA Frame is the sole body-on-frame architecture to serve
Ram pickups and commercial vehicles - but not definitively
Jeep Wrangler. Projected operating ranges are up to 500
km/300 mi (small); 700 km/440 mi (medium); 800 km/500
mi (large), and 800 km/500 mi for STLA Frame, Wester said.
Powertrain strategy is " centered around flexibility and modularity, "
explained Micky Bly, VP and head of Stellantis' Global
Propulsion Systems. The latest EV drive technology, the company's
third generation, is " aimed at producing a scalable design that's
compact and has a high level of reuse. " The integrated 3-in-1 electric
drive module (EDM) assembly is scalable from 70 kW to 330 kW.
An important part of the propulsion strategy is developing one
power inverter for all three EDMs. The inverter features a common
microprocessor and in-house-developed proprietary controls and
software. It's designed to reduce cost and complexity for fast-tomarket,
Bly noted. " The inverter will run at 400V and 800V and has
phase-current capability from 350A to 750A to deliver up to 350
kW of power. " Its " heart " is a selectable power device that is either
silicon-based or silicon-carbide based, depending on application.
Bly claimed the new inverter will have " the most advanced
wide-band semiconductors that are optimized to handle the
electric loads, switching rates and other performance capabilities
to best control energy consumption on the vehicle.
This flexibility allows us to go from very cost-effective to extreme
high-performance vehicles. "
Battery chemistry logic
Stellantis' two-lithium-chemistries battery strategy - one ironmanganese-based,
the other a cobalt-free nickel manganese
- is " based on two operating points with a high level of synergies
in between, " explained Personnaz. The latter offers 20%
lower cost at the pack level, with energy densities between
400-500 Wh/L. The other delivers high energy density, between
600 and 700 Wh/L. " We have one unique modulebased
design for all our battery platforms, " Personnaz noted.
Pack installations are similar, and both are upgradable.
Stellantis' battery partners include Automotive Cells Co.
(ACC), a joint venture with Total Energies-Saft; BYD Co.;
Contemporary Amperex Technology Co. Ltd. (CATL); LG
Energy Solution; Samsung SDI and SVolt.
Battery packs are designed as " a very simple one-layer
concept to be deployed on all platforms by 2024, " Personnaz
noted. He added that advanced battery management design
" enables us to push the depth-of-discharge limits and enhancing
the voltage measurement accuracy. For a given embedded
energy we increase the usable energy by 4 percent.
We expect to be ahead of the [battery] race by 2024. "
Lindsay Brooke
6 July/August 2021
TESTING
Radiated emissions testing gathers
bandwidth
Test chambers include semi-anechoic enclosures with RF-absorbing ironferrite
cores and ferrite-impregnated foam. When the door is closed, there
is a 100:1 dB separation factor.
In a non-descript business park in Auburn Hills, Michigan,
Bureau Veritas (BV) is conducting tests to help prevent electronic
havoc. With today's vehicles chock full of wired and
wireless devices - and tomorrow's more automated machines
destined to expand the complement - ensuring this burgeoning
technology isn't radiating disruptive frequencies will be
crucial to expanding functions and features. For the coming
electric/autonomous age, radiated frequencies will become
the new emissions challenge.
Often summarized as electro-magnetic compatibility (EMC)
testing, the BV facility (which sits in sight of the re-christened
Stellantis North American HQ) provides a host of testing, inspection
and certification services designed to simplify and
speed vehicle development. The Motown BV crew does this
by helping to ensure electronic components don't radiate
spurious electromagnetic interference known as radiated and
conducted emissions, and that they remain functioning even
when subjected to such fields.
Netting GM approval
In May 2021, BV announced its Detroit-area automotive lab
had gained official approval from General Motors in respect
to automotive EMC specification GM W3097:2019. What does
this equate to in practical terms? " What that means is we're
doing EMC testing - radiated immunity, radiated emissions,
bulk current injection, transient immunity, and electrostatic
AUTOMOTIVE ENGINEERING
SAE
Automotive Engineering - August 2021

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