Zonal E/E will transform automotive architectures Page 12
AUGUST 2023
The future of autonomy for on-highway vehicles Page 15
What is a traction motor and when should you use one? Page 27
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Contents
Automotive & Transportation Electronics Handbook
06
18
Smarter, safer, cheaper: how Ethernet will
enable the car of the future
The implementation of Ethernet as a universal standard
throughout the automotive industry can optimize vehicle
performance by reducing the number of electronic
control units (ECUs) and associated wiring, thus enabling
a smarter, cheaper, and safer future car.
10
22
27
32
The future of autonomy for on-highway
vehicles
DESIGN WORLD — EE NETWORK
What is a traction motor and when should
you use one?
Traction motors are optimized for locomotives, EVs,
elevators, and other situations where high torque at
start-up and low speed is needed.
Zonal E/E will transform automotive
architectures
The road to fully autonomous commercial vehicles
is paved with unique challenges but accelerated
technologies to smooth the way.
2
Advancing automotive networks: robust ESD
protection for Ethernet applications
ESD protection devices act in synergy with the rest
of the circuitry resulting in a robust system against
destructive ESD and EMC.
The transition from numerous ECUs to zones will occur
over several years from roughly 2025 to 2030. Each OEM
will use its own architecture.
15
Depending on the system architecture and functions
included, IVIs can be implemented with highperformance MCUs or with SoCs.
Multiple-channel power monitors for
automotive applications
MCPMs can simplify system design and contribute to
the overall performance and reliability of the electronic
system.
12
How do MCUs support automotive
infotainment systems?
08 • 2023
Testing batteries for an evolving world
Battery testing enables vehicle manufactures, owners,
and researchers to make informed decision, optimize
vehicle performance, and enhance overall user
experience.
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Smarter, safer, cheaper:
how Ethernet will enable
the car of the future
The implementation of
Ethernet as a universal
standard throughout
the automotive industry
can optimize vehicle
performance by
reducing the number of
electronic control units
(ECUs) and associated
wiring, thus enabling a
smarter, cheaper, and
safer future car.
Ramin Shirani, Ethernovia
CEO and Co-Founder
IT
has become a common refrain among buyers of new cars to say, “It feels like
I’m driving a spaceship.” In some regards, that feeling is valid — beneath the
hood, modern vehicles, like spaceships, run akin to supercomputers. Thus, OEMs are
feeling increased pressure to simultaneously increase the ability for vehicles to quickly
process ever-growing amounts of data while simultaneously decreasing vehicle network
architecture.
As vehicles continue to evolve and offer everything from more immersive
entertainment features to safer, more precise autonomy, this problem will worsen.
One solution, however, has the potential to enable the next evolution of automobiles:
Ethernet.
Implementing in-vehicle Ethernet
Robert Metcalfe and his colleagues at the Xerox Palo Alto Research Center invented
Ethernet in the 1970s to, in Metcalfe's words, solve the problem of connecting a building
full of personal computers without creating a centralized “rat’s nest” of wires. Ethernet,
simply, is the single-cable solution that Robert and his team ultimately created.
In an automotive capacity, Ethernet acts largely the same: when combined with
sufficiently advanced chipsets, it significantly reduces the complexity of a typical vehicle’s
networking system. In automotive terms, that equates to domain vehicle architecture
(Figure 1) versus Ethernet-based centralized vehicle architecture (Figure 2). Automotive
Ethernet, however, is built to withstand more difficult conditions than faced by a typical
data center — automotive Ethernet is built to operate in environments of varying climates
and terrains of varying toughness.
Vehicle architectures today are evolving away from domain-centric controllers and thus,
vehicular networking capacity must be able to process the higher data rates necessitated
by advanced applications like Advanced DriverAssisted Systems (ADAS), autonomous driving
(AD), and a wide range of software updates
delivered over the air (OTA). Challengingly,
the future vehicle must meet these demands
while simultaneously delivering improved
reliability and security.
Ethernovia’s Ethernet-based architecture
is designed to enable a seamless, holistic,
Figure 1. Domain architecture diagram
of current generation mid-tier
automobile model.
6
DESIGN WORLD — EE NETWORK
08 • 2023
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IN-VEHICLE ETHERNET
Figure 2. Example of car
manufacturer’s upcoming
centralized architecture diagram
incorporating Ethernovia’s Ethernetbased chip solution.
and streamlined hardware and software
system that meets this demand through the
integration of advanced networking features
targeting the future of software-defined
vehicles.
So, why the shift to Ethernet now?
Ethernet actually began to appear in
mainstream automotive implementations a
decade ago. BMW were the first to introduce
Ethernet in consumer vehicles back in 2008;
since then, more than 90 percent of car
manufacturers have incorporated Ethernet in
their vehicles.
Several features then laid the path
for Ethernet’s wider automotive adoption.
Ethernet ‘T1’ transceivers were designed to
meet the stringent OEM EMI/RFI requirements
for the automotive market as well as reducing
75 percent of the copper cable, by operating
over a single pair as opposed to the four pairs
used for Enterprise Ethernet. This reduction
had a significant impact on the weight and
cost of the wiring harness. Additionally,
Ethernet’s open standard environment meant
there were several suppliers creating solutions
as opposed to the single vendor solution for
some of the legacy automotive technologies
— driving innovation and providing secondsource options, which are key for automotive
OEMs.
Finally, enhancing network protocols took
traditional ‘best-effort’ Ethernet and provided
time-bound, guaranteed delivery of in-vehicle
data.
In the last decade, and with the
continuous forward momentum in features
and speeds available, we have seen Ethernet
move from deployment in diagnostics and
infotainment to deployment throughout all
domains in the vehicle.
Enabling a Smarter Vehicle
As shown in Figure 1, many different
networks exist in cars today to connect
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ECUs in the vehicle. With the advent of new
features making cars ever smarter, there is a
perpetually increasing amount of bandwidth
in the car to support these applications. OEMs
need increasing compute resources to deal
with this data while simultaneously simplifying
the vehicles with the consolidation of ECUs.
The result? A huge demand for
high bandwidth, low latency, and secure
networking technology to efficiently move
data around the vehicle.
In 2022, Forbes solicited predictions
from technology experts on the features
they expected to see in future vehicles. The
predictions were wide-ranging: autonomy,
of course; cars serving as fully functioning
office spaces with 5G connectivity;
advanced artificial intelligence and machine
learning capabilities; enhanced privacy and
cybersecurity; augmented reality navigation;
and more.
Future vehicles with these capabilities
can never be built on the networking
infrastructure most automakers have in
place today given the requisite increase in
processing demand. An Ethernet-based,
in-vehicle, end-to-end networking solution as
the backbone, auto engineers and designers
will be empowered to realize the smart ‘future
cars’ the technology industry and automotive
evangelists prognosticate about today.
Enabling a safer vehicle
A subset of the smart(er) vehicles is ADAS and
AU, which have evolved significantly over the
past decade. The two exist across six levels of
complexity:
Level 0: Manual driving
Level 1: Driver assistance
Level 2: Partial automation (“feet off”)
Level 3: Conditional automation (“hands off”)
Level 4: High automation (“eyes off”)
Level 5: Full automation (“mind off”)
The majority of cars today actually exist at
08 • 2023
level zero — fully manual — with newer
vehicles implementing level one and level
two. Progressing beyond those levels requires
an exponentiating amount of bandwidth
which can be seen in Figure 3.
Such progression, however, is necessary
to ultimately improve safety on the road.
A 2017 report from the U.S. Department
of Transportation National Highway Traffic
Safety Administration found human error to
be the “major factor” in 94 percent of all
fatal crashes. A 2018 report from Automotive
Management stated:
The growing penetration of ADAS, such
as automated emergency braking, blind spot
monitoring, and lane assist will result in a
15% reduction in the number of accidents
in the four main European markets (France,
Germany, Italy, and the UK) by 2030.
Sufficiently advancing ADAS and AU
technology begins with a capable vehicle
network — and that begins with an Ethernet
and silicon-based solution.
Enabling a cheaper vehicle
Moving forward, OEMs are trying to further
consolidate ECUs and functions. Ethernet
aggregates traffic into a single backbone,
reducing the need for a complex wiring
harness, associated connectors, and myriad
required legacy transceivers. This aggregation
provides a significant cost saving to the OEMs
with the added benefit of security, simplicity,
and — very importantly — weight reduction
using the ‘T1’ single-pair automotive
transceivers.
For consumers, lighter vehicles equate to
greater fuel economy. According to the U.S.
Department of Energy, “a 10 percent reduction
in vehicle weight can result in a 6 percent-8
percent fuel economy improvement.” The
Department of Energy also underscores the
importance of weight reduction in enabling
longer-range electric vehicles:
DESIGN WORLD — EE NETWORK
7
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Figure 3. The five levels of ADAS systems and corresponding total bandwidth requirements.
While any vehicle can use lightweight materials, they are
especially important for hybrid electric, plug-in hybrid electric, and
electric vehicles. Using lightweight materials in these vehicles can
offset the weight of power systems such as batteries and electric
motors, improving the efficiency and increasing their all-electric
range. Alternatively, the use of lightweight materials could result
in needing a smaller and lower-cost battery while keeping the allelectric range of plug-in vehicles constant.
Range anxiety represents one of the top concerns hindering
the broader purchasing of electric vehicles, with the World
Economic Forum, citing a 2022 study by EY, noting about onethird of drivers worldwide express concerns about driving long
distances in these vehicles.
So, by making vehicles lighter, OEMs benefit in
manufacturing costs, consumers benefit in extended fuel range,
and the planet, by extension, benefits from the wider adoption of
non-carbon-emitting vehicles.
8
DESIGN WORLD — EE NETWORK
08 • 2023
Looking to the future
A major proof point in the market’s belief in the further
complexification of vehicles is the forecasted segment growth
over the next decade. Future Market Insights estimates the global
automotive connectivity market to grow from $33.42 billion today
to $190.29 billion by 2033.
Consumers have seen the promise of vehicular innovation
and the promises they hold for smarter, safer, and cheaper driving
options. That future will be realized, but only if networks can
process increasing demand. Ethernet is the best solution to meet
that demand.
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Multiple-channel
power monitors for
automotive applications
MCPMs can simplify system design and contribute to the
overall performance and reliability of the electronic system.
Mitch Polonsky,
Microchip Technology
and power monitoring are
CURRENT sensing
essential design aspects of several
automotive systems. Moreover, some kinds of automotive modules
may need more than one of these sensing/monitoring operations.
Multi-channel power management (MCPM) ICs can help in this
regard. They can incorporate up to four energy monitoring
channels, including bus voltage monitors and current sense
amplifiers. Thanks to their recent Automotive Electronics Council
(AEC) AEC-Q100 stress test qualification for packaged integrated
circuits (ICs), these MCPM devices can serve in several automotive
applications.
The measurement, monitoring, and control of power is
increasingly important for all kinds of electronic systems. Power
management can promote power efficiency, optimize the remaining
battery life or enhance other power-related system functions. At
its most basic level, power monitoring circuitry usually consists
of a sense amplifier circuit operating across a sense resistor. This
basic configuration can monitor current, voltage, and power data
through an analog output. The sense amp is typically energized
continuously and lacks more advanced functions such as the ability
to poll the circuitry and interrupt circuit operation to reduce power
consumption.
Contrast this basic current sensing with the actions of a digital
power monitor or precision power monitor. This scheme is also
called a high-side current sensor and can have other monikers as
well. An IC capable of making and digitally communicating more
than a single current sensor measurement is more accurately
described as an MCPM.
An MCPM can connect to a higher voltage rail without the
need for additional protection devices. The newest family members
(PAC194X/5X) can measure 0 to 32 V. Measured values go
digitally over a two-wire I2C/SMBus to a host computer. The power
monitor calculates power consumption on-chip independently of
the host controller and makes this value available in a register.
This approach saves software overhead, development time, and
reduces code complexity associated with monitoring one or more
current sensors.
With the appropriate data, the host can proactively disconnect
loads to save power and reconnect them as needed. This process
also saves time in the awake state while the sensor accumulates
data. Additionally, power monitoring activities managed by the
host processor can be put to sleep, leaving more of the remaining
10
DESIGN WORLD — EE NETWORK
Figure 1. The simplest form of current sensing has a single analog output.
processing power for the other activities.
The PAC194X/5X is a family of MCPM ICs with up to four
bidirectional, high-side/low-side current-sensing channels. Also
included are precision voltage measurement capabilities, an
integrated power calculation, and a power accumulator. PAC194X
devices are specifically designed for lower voltage applications.
With 16 bits of resolution, the voltage rail spans 0 to 9 V without
requiring additional circuitry. Such qualities make the chips good
candidates for dual-cell Li-Ion battery applications. A configuration
Figure 2. In an MCPM application, data communicated by the I2C/SMBus
as well as alerts/interrupts allow a host computer to efficiently provide
power control.
08 • 2023
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MCPMS FOR AUTOMOTIVE
Figure 3. A fourchannel dc power
monitor with
accumulator — two
16-bit ADCs provide
accuracy and high
resolution to I2C/
SMBuscommunicated data.
of 0-to-4.5-V single-cell Li-Ion applications
can be realized with the same 16 bits of
precision. This allows the ICs to be used
for accelerator cards, field-programmable
gate arrays (FPGAs), graphics, telematics,
computing, and more.
Two flexible alert outputs can help
define, capture, warn, and report to the host,
alerting it to take the appropriate actions.
Thanks to two digital outputs, a spurious
current event can be captured separately
from a spurious voltage event; consequently,
the ICs can respond distinctively differently to
the two kinds of anomalies. Another option
would be to measure or mask over-voltage
(OV), over-current (OC), and over-power (OP)
as well as under-current (UC) and undervoltage (UV) occurrences. Such options
greatly simplify and improve the system’s
response to different power situations.
MCPMs can measure the voltage
and current simultaneously with a 16-bits
resolution for each. The measurement
limits of the two flexible alerts can easily be
adjusted by configuring a 16-bit limit register
for desired current-voltage events and a
wider register for power events.
Power savings
One challenge in power monitoring is
the amount of current consumed when
measuring power. A single power monitor
can draw up to 360 µA or more. In contrast,
an MCPM can use at least 31% less current
than a single-channel device that makes
two measurements. In this case, the twochannel system only pulls 495 µA compared
to 720 µA for two single devices.
The difference in current consumption
is even greater with more channels; it is
54% lower with a three-channel system and
66% with a four-channel system. The need
to draw less current with multiple devices
also saves printed circuit board (PCB) space
and simplifies layout.
MCPMs are also suitable for use in
vehicles. It is interesting to note that in
a typical automotive telematics or radio
head module, there can easily be three or
more current/voltage nodes to monitor.
The PAC194X/5X MCPMs have passed
AEC-Q100. The Automotive Electronics
Council established AEC-Q100 as a failuremechanism-based stress test qualification
for packaged ICs employed
in automotive applications.
AEC-Q100 basically extends
IEC and Jedec specifications
for automotive uses. An AECQ100-qualified device has
passed specified stress tests
that guarantee a certain level of
quality/reliability. For example,
AEC-Q100 for grade-two
semiconductor components
requires high-temperature
operating life (HTOL) testing of
1,000 hours at 125°C. Typical
automotive application examples
include graphics cards, dc-dc
converters, power inverters, fan
control, and more.
Figure 4. A multi-channel power monitor reduces current
dissipation over a single channel from 31% to 66%.
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08 • 2023
Electrostatic discharge also plays a
significant role in automotive quality. The
PAC194X/5X devices tolerate 7,500-V HBM
(human-body model) and 4,000V CDM
(charged-device model). HBM simulates
ESD caused by discharge from human
beings. CDM simulates the discharge
of a charged device when it touches a
conductive material.
There are two versions of the PAC195X.
PAC195X-1 devices are for high-side current
sensing; PAC195X-2 devices are for lowside current sensing or floating Vbus
applications. The high impedance input of the
PAC194X/5X design allows for longer traces
on the PCB (up to 1 kΩ) associated with the
sense resistors. Thus, sense resistors can be
physically separated as is often necessary for
quantifying multiple (up to four) current flows
from disparate sources.
The PAC194X provides a unique 16-bit
resolution on lower Vbus measurements
supporting 4.5 and 9 V, while the PAC195X
supports 16 and 32 V (with 40 V being the
absolute maximum for both families). For
applications up to 60 V, a floating voltage
node with a resistor divider can be used to
keep the voltage under 40 V.
The PAC194X/5X family features a
wide dynamic measurement range that
enables low-power events — such as trickle
charging — and high power-consumption
events — such as battery charging — to
use the same voltage rail. This feature
eliminates the need for separate coding
specific to each of these events. It is the 16bit resolution in the PAC194X/5X family that
makes this simplification possible.
In addition, extensive driver support,
including MPLAB Code Configurator,
MPLAB Harmony, Python code, and
Windows 10/11 drivers, is available with
Linux drivers coming soon to simplify
software development.
For prototyping, a burst mode
measurement allows increasing the
measurement speed or sampling rate
for one rail and using it for better singlechannel characterization and prototyping.
Power accumulation registers additionally
help the designer to better understand the
system over time.
References
Microchip Technology, www.microchip.com
DESIGN WORLD — EE NETWORK
11
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Zonal E/E will transform
automotive architectures
Image: Adobe Stock
12
DESIGN WORLD — EE NETWORK
08 • 2023
08 • 2023
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ZONAL E/E
The transition from numerous ECUs to zones will occur
over several years from roughly 2025 to 2030. Each OEM
will use its own architecture.
Ray Notarantonio, Jeff Kelley,
and Seongman Jeong, Infineon Technologies
LONG
before the smartphone, the
number of interconnected
electronics and electrical equipment on
automobiles, especially high-end vehicles,
led pundits to describe a car as a computer
on wheels or digital car. More recently, with
IoT terminology attached to any wired or
wireless electronic product connected to the
Internet, cars have now become the IoT on
wheels. To continue the progress yesterday’s
interconnected vehicle into the future, the
electrical/electronics (E/E) architecture must
evolve to address increasing complexity,
speed of getting to production, ongoing
updates during the life of the vehicle, and
network/vehicle-wide security, all while
offsetting computing cost increases by
reducing system integration costs.
Evolving vehicle networks
Today, automotive experts are proud to
cite the presence of 60 to 100 traditional
electronic control units (ECUs) on an average
vehicle, each with a computing core —
microcontroller (MCU) — to provide the
various features and functions that car buyers
want. This number should shrink as the
vehicle architecture changes from distributed
to zonal designs with central computer
systems (CCS). With all the legacy hardware
and software that currently provides the
desired functions and proven reliability, the
transition will not occur without intermediate
steps. Besides timing considerations, safety
and security must be paramount to obtain the
full benefits of the transition.
From roughly 2025 to 2030, computing
could be based on using two or more
central computer systems with several zone
controllers that aggregate functions from
previous ECUs. Figure 1 shows Infineon’s
vision of how this could occur. In addition to
the various zone modules, power distribution
systems (PDS) will also be a critical element
of new vehicles.
In today’s vehicle architecture, an ECU
typically controls an entire domain such as
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08 • 2023
a powertrain or chassis. It’s cumbersome to
control and difficult to update the software
because the ECU has no direct connection to
the outside world. In the new zonal approach,
the geographic arrangement aggregates
hardware and software independent of the
domain, which means fewer, easily softwareupdateable ECUs. Several CCSs perform
high-level processing. One CCS could address
cockpit domain control (CDC) and networking
functions — typical body electronics systems.
A second CCS would handle advanced driver
assistance systems (ADAS) including image
processing.
The transition process
In the 1990s, OEM efforts to develop a
standard approach to vehicle network
communications led to SAE J1850 with unique
versions for Chrysler, Ford, and GM. Other
OEMs are also taking their own unique paths
for zonal architectures.
In this approach, the central computers
do the high-level processing with actions
carried out by the zone control units (ZCUs).
These ZCUs interface with satellite sensors
and actuator modules at the edge of the
vehicle’s platform. The ZCU middleware
enables a future with flexible softwaredefined vehicle (SDV) features, constantly
updated by the OEMs.
Another variation of this architecture
for the 2028-30 timeframe is the layered
approach. This architecture consists of:
• An upper, high-performance central
computing layer consisting of modules
for real-time control and for Adaptive
AUTOSAR (AA) or POSIX;
• A layer with as many as 5 to 10 zones
that are ASIL D capable and include
chassis, body, and safety ECUs;
• The lowest layer that has intelligent
edge devices including a mix of smart
sensors and small ECUs, PDS elements,
and other miscellaneous legacy
hardware.
DESIGN WORLD — EE NETWORK
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Figure 1. E/E architectures from 2025 to 2030 will consist of CCS, zones, PDS, and legacy components.
Issues in developing/adapting a new
architecture
OEMs are initially pulling body systems
into zones. In this transition phase, the
powertrain in battery electric vehicles (BEVs)
could be among the last to have a zone.
Some possible implementations mix body
and safety domains into a zone. Others
doing zone controllers try to avoid ASIL A
and ASIL B overlap because if they co-exist,
then both require ASIL-B qualification and
work products. That means higher costs and
greater system complexity.
Another system aspect is how OEMs
deal with wake-up considerations. Today,
many inputs can wake-up a car: door
handles, remote keyless entry (RKE), the
liftgate, smartphones, and more. Since these
wake-up inputs can go into different ECUs,
coordinating and managing the wake-up
at the vehicle level is challenging. When
to wake-up and how to wake-up a vehicle
will become much more decentralized and
software dependent in future vehicles.
One of the design goals of these new
architectures will be over-the-air (OTA)
updatability, to provide unprecedented
flexibility in new features, updates, and
services. OTA introduces greater security
risks and offers solutions to resolve
them. The new ISO21434: Road vehicles
— Cybersecurity engineering, outlines
processes and methods to support security
in these new automotive architectures.
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DESIGN WORLD — EE NETWORK
Coexisting vehicle architectures
Because the complete ramifications of any
new architecture are not fully understood at
this point, OEMs could react quite differently
based on their design considerations
and strategies. ZCUs tend to be body
applications, but at some OEMs, they could
be body and safety or safety and powertrain
applications, or even vehicle motion,
chassis, and propulsion in one. Those are
different implementations that could be put
into zones. The zone concept itself is the
common theme with the CCS on top and
legacy systems below that do not have to
significantly change. For example, in the
legacy portion, a fuel pump does not need
to change very much because its function
— innovation is not required. It is probably
not going to be incorporated into a zone
controller because the electronics could
even be embedded in the fuel pump itself
and it just needs network connectivity.
Automotive electronics advancements
New E/E architectures will ultimately change
the way engineers design and implement
vehicle electronics. These changes, however,
will take several years to implement because
they will not replace legacy ECUs all at
once. While existing vehicle models will not
be redesigned to fit a new or transitional
architecture, the need to have OTA
updateable software and software-based
services could accelerate the timing.
08 • 2023
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AUTONOMOUS COMMERCIAL VEHICLES
Image: Adobe Stock
The future of autonomy
for on-highway vehicles
The road to fully autonomous
commercial vehicles is paved with
unique challenges but accelerated
technologies to smooth the way.
Lisa Viazanko, Vice President, and
CTO of Industrial, Commercial
Transportation, TE Connectivity
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THE
The promise of fully autonomous on-highway vehicles
has enthralled manufacturers, consumers, and media
alike. The world awaits a future where trucks, buses, and emergency
vehicles can be operated entirely by automation and respond to
ever-changing environmental and traffic conditions. The automated
trucks and buses market is expected to grow to 1.2 million vehicles
by 2032, or 19% of the total market. China will lead the way in the
adoption of autonomous commercial vehicles, with 38.5% share,
followed by Europe and North America with 29% and 26% share,
respectively.
In this brave new world, fully autonomous commercial vehicles
will operate on a 24/7 basis: overcoming driver shortages and
fatigue, smoothing out traffic, and reducing gridlock and accidents.
Fleet operators will be able to handle more cargo, driving more
revenues while reducing the total cost of ownership of trucks by 45%.
Commercial vehicles can sense and respond instantly and
seamlessly to traffic light changes, road congestion, heavy rain and
snowfall, pedestrians, and more. In addition, automated trucks,
08 • 2023
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
buses, and emergency vehicles won’t be prey
to unsafe drivers who take unnecessary risks,
such as failing to signal, making unexpected
lane changes, weaving in and out of traffic,
and suddenly stopping. Since 94% of vehicle
accidents are due to driver distraction
or error, traffic injuries and fatalities will
ultimately plummet.
So, where are we headed, and what
can commercial vehicle makers and logistics
operators expect from their original
equipment manufacturer (OEM) and
component manufacturer partners? After all,
investors have invested more than $330 billion
in automation, connectivity, electrification, and
smart mobility (ACES) companies since 2010,
with more than a third going to autonomous
vehicle technologies. Why haven’t
manufacturers deployed fully autonomous
commercial vehicles on the road yet?
Progress toward reaching
Level 5 automation
Automated vehicles are rated on a scale of
Level 0, or no automation, to Level 5, or full
automation. The on-highway vehicle industry
is currently at Level 2, or partial automation.
Drivers benefit from technology such as
advanced driver assistance systems (ADAS),
which help them maneuver and park oversized
commercial vehicles.
Commercial vehicle manufacturers are
also borrowing best practices from auto
manufacturers, which are leading in innovation
thanks to significant funding in the space.
Auto manufacturers such as Tesla and General
Motors offer automated driving functionality
classified as Society of Automotive Engineers
(SAE) Level 2 in the U.S. At the same time,
Mercedes-Benz has achieved approval in
Germany in 2022 for Level 3 automated driving
and is the first carmaker to achieve approval
in Nevada USA to deploy cars with Level 3
automated driving. Pony.ai has launched robotaxis in China with a safety driver monitoring
service, while Waymo and Cruise are about to
do the same in San Francisco.
With so much investment and innovation,
Level 5 automation for both on-highway and
passenger vehicles will likely be achieved
this decade. Industry watchers believe that
fully autonomous trucks will lead the way, as
highway driving is easier to master than the
unpredictable urban and suburban driving
conditions experienced by route vehicles such
as buses and passenger vehicles. In addition,
the expected 45% reduction in the total cost
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DESIGN WORLD — EE NETWORK
of ownership
for autonomous
trucks more
than justifies the
investment in
the higher level
of computing,
AI, and sensor
performance,
removing cost
as a barrier to
adoption.
Addressing
technical
obstacles to
deploying
automation at
scale
Figure 1. Levels of
autonomy in
on-highway vehicles.
Numerous technical obstacles must be
overcome before manufacturers can gain
regulatory approval for fully automated
commercial vehicles produce and deploy
them at scale.
These challenges include:
Aligning electrification and
automation objectives:
Commercial vehicles are electrifying at a fast
pace. Vehicle manufacturers want to futureproof their businesses, while fleet operators
want to pivot away from using fossil fuels and
reduce energy costs. There are multiple paths
to electrifying commercial vehicles, including
developing conventional hybrids, plugin
hybrids, battery electric vehicles, and hydrogen
fuel electric vehicles.
This means that more technology,
including high-voltage equipment, is now
going under the hood of vehicles, which is why
component manufacturers are miniaturizing
systems where possible. One strategy is
to co-locate power and data transmissions
using electromagnetic shielding in a hybrid
connector. By doing so, commercial vehicle
manufacturers can minimize space while
enabling the side-by-side location and
transmission of electrical current and highspeed data signals.
Ensuring pervasive communications:
Each autonomous vehicle will be packed with
technology, including sensors, connectivity,
and artificial intelligence. Trucks, buses,
and emergency vehicles collect data from
multiple devices, including RADAR/LiDAR,
cameras, antennas, displays, and telematics.
08 • 2023
This technology will ultimately capture vast
amounts of data at more than 25 gigabits
per second. The industry will evolve from
powering in-vehicle communications
governing systems like ADAS to enabling
vehicle-to-vehicle (V2V) and vehicle-toeverything communications (V2X). Achieving
this vision is some years ahead. Automation
and artificial intelligence need to process
data in real time, enabling vehicles to react to
changing road conditions and the actions of
other vehicles. That’s much more challenging
for commercial vehicles, which can’t react
as quickly as smaller passenger vehicles. So,
suppliers of connectivity and sensor solutions
must consider the physics of key processes,
such as unexpected braking, and recalibrate
commercial solutions to react faster to enable
preventative actions.
Currently, many commercial vehicles use
CAN networks that transmit data at slower
speeds. As a result, automobile, OEM, and
component manufacturers are working on
developing new Ethernet standards that will
enable ultra-fast communications in harsh
environments. The 100 BASE-T1 and 1000
BASE-T1 Ethernet protocols can transmit
high amounts of data using an unshielded
twisted pair, compared to only 400 kB with
CAN and 1 MB with CAN-FD. Meanwhile, the
automotive ethernet is at 25 Gbps and will
reach 100 Gbps soon. Commercial vehicles
typically require 1000BASE-T1bp Type B,
which provides a longer channel length
that accommodates the longer distances
between systems like cameras and displays
in commercial vehicles. Next-generation
architectures will use a mix of CAN and
Ethernet protocols, aligning them to the
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AUTONOMOUS COMMERCIAL VEHICLES
functionality they support.
Systems and devices are
interconnected via onboard networks,
enabling high speeds of data
transmissions. Data is then processed
via one or more electronic control units
to create a real-time view of vehicle
performance, conditions, and the
surrounding environment. Ethernet
connectors help enable data connectivity
by providing wire-to-wire connections
supporting digital services and operations,
such as multifunction displays, telematics,
telemetry units, infotainment modules, and
media access controllers. They are sealed
to ensure flawless performance with heavyduty usage and have secondary locking to
ensure contact retention.
Operating in harsh environments:
Commercial vehicles must withstand
punishing operational and environmental
conditions. They may operate around the
clock for years on end, must withstand
vibration and shock, and often operate in
environments characterized by extreme
temperatures ranging from -40°C to 125°C,
dust and gravel, moisture, and corrosive
fluids. Finally, tractors and trailers may be
connected and unconnected frequently,
which is hard on connector solutions.
Component manufacturers are developing
solutions, such as rugged connectors that can
withstand these operating and environmental
conditions and can be serviced in the field to
get
vehicles up and running again. Connectors
with low insertion force can handle more wear
and tear, such as trailers being connected and
disconnected constantly while still preserving
data connectivity.
Gaining regulatory approval
to deploy new functionality:
Commercial vehicle manufacturers and
technology providers are testing new
functionality, such as automated lane
changing in controlled environments, to test
and learn how vehicles perform and solve
issues before seeking regulatory approval.
They’re learning from passenger vehicle
trials which are now happening globally.
Commercial vehicle manufacturers want
to know that technology is safe and works
effectively before deploying automated
capabilities at scale. They need to ensure
regulatory and public acceptance of new
systems, while technology providers want to
avoid the liability of accidents occurring due
to unproven systems.
OEM and component manufacturers
who develop products according to the
latest standards and best practices can
help commercial vehicle manufacturers
meet exacting regulatory requirements.
Selecting the right partners for
the journey ahead
Commercial vehicle manufacturers have
invested hundreds of millions of dollars
researching new technology, developing
next-generation architectures, and testing
solutions. Teams at these leading
companies want to work
with partners with
the demonstrated
expertise, breadth
of solutions,
and global
manufacturing
expertise to
help them close
the last mile of
autonomous
driving.
Leading
component
manufacturers
can provide the full breadth of sensors,
antennas, connectors, cable assemblies,
and data connectivity required for
autonomous capabilities. They offer both
standardized and customized solutions
to meet customer needs. Component
manufacturers can use 3D printing and
injection molds to fabricate customized
connectors and provide wire harnesses
for customer testing if customization
is required. Doing so at pace enables
commercial vehicle manufacturers to
maintain their desired rate of innovation.
Component manufacturers must meet
customer requirements for:
• Increasing safety: Providing
solutions that offer extreme reliability
and responsiveness amidst changing
conditions.
• Enabling greater productivity:
Delivering the full range of solutions
that will allow greater automation of
commercial vehicles so that operators
can run them 24/7 to increase delivery
throughput.
• Improving sustainability: Providing
solutions that support vehicle
electrification; reduce componentry
weight; and use sustainable, affordable
resins, materials, and processes.
• Creating a connected world: Those
component manufacturers that run
diversified businesses can bring
insights, best practices, and solutions
from other divisions, such as energy,
engines, infrastructure, and passenger
vehicles, to bear on innovating solutions
for commercial vehicle manufacturers.
Commercial vehicle manufacturers
and their partners have created a solid
foundation for developing autonomous
vehicles. They’re solving challenges around
electrification, component miniaturization,
data connectivity, and performance in
harsh environments that will unlock faster
innovation in the future.
Commercial transportation will
increasingly become autonomous within
the next decade, unlocking new business
gains for manufacturers and operators
while contributing to a safer, more
sustainable world.
Figure 2. TE's heavy-duty sealed
connector series is ideal for making
powerr and data connections in
rugged applications.
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08 • 2023
DESIGN WORLD — EE NETWORK
17
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
How do MCUs support
automotive infotainment
systems?
Depending on the system
architecture and functions
included, IVIs can be implemented
with high-performance MCUs or
with SoCs.
Jeff Shepard
IN
vehicle infotainment (IVI) systems are increasingly important
and complex. What’s needed from a microcontroller (MCU)
in an IVI? A lot, but exactly what depends on the sophistication
and mix of info and ‘tainment. Multiple cores are often needed,
and so are hardware accelerators for compute-intensive functions.
Considerations include connectivity, human-machine interfaces
(HMIs) beyond simple flat panel displays, memory management,
and more. Software-defined functionality and over-the-air (OTA)
updates are also important.
This article begins with a brief overview of IVI functions
including emerging advanced functions like driver attention
monitoring and gesture recognition, looks at the growing demand
on IVIs for expanded connectivity, presents a typical IVI system
architecture, typical IVI MCU functionalities, and a typical IVI system
on chip (SoC) and closes with a brief review of security and safety
standards related to IVIs and other automotive systems.
IVIs provide the command center for vehicle operations
and support for essential services. The cockpit domain controller
coordinates driver information and control functions using touch
Figure 1. IVI systems provide a wide
range of information and entertainment
functions and connectivity (Infineon).
Image: Adobe Stock
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DESIGN WORLD — EE NETWORK
08 • 2023
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AUTOMOTIVE INFOTAINMENT
are the five levels of vehicle connectivity?”
Smartphone connectivity is growing in
importance in IVI systems. It includes Wi-Fi
networking and wireless charging. Bring-yourown-device (BYOD) connectivity is supported
by several IVI SoCs that tightly integrate users’
smartphones with the IVI system. And the IVI
connects to the car’s CAN bus, Ethernet, USB,
PCIe, and other wired networks.
5G is replacing 4G as the standard for
IVI systems. Its higher speeds can support
higher definition maps, updated in real-time
with weather and traffic information, and new
services ranging from vehicle diagnostics to
interactive entertainment. IVIs are beginning
to incorporate graphic processing units
(GPUs) to support gaming and subscriptionbased services.
OTA updates are becoming important
for IVI systems. OTA improves system
operation over time by allowing car makers
to update existing features and fix bugs.
5G cloud connectivity is becoming a key
element supporting OTA for IVIs and for the
overall vehicle.
IVI system architecture
monitoring systems are beginning to appear
and are expected to be mandated by safety
regulatory bodies. These systems will require
an IVI that can identify the driver and monitor
facial features to determine driver attention.
Gesture control is being developed
for IVI systems. Technologies for gesture
recognition include mmwave radar and
ultrasonics. Vertical-cavity surface-emitting
laser (VCSEL) technology is also being
considered for gesture recognition. IVI SoCs
will incorporate machine learning accelerators
to support improved accuracy.
IVI control units support a wide range of
functions like (Figure 2):
• Wired connectivity including CAN-FD,
Ethernet, USB, display connectivity, and
others.
• Sensors including cameras, MEMS
microphones, gesture recognition
subsystems, inertial measurement units
(IMUs), and so on.
• Audio including a mix of class AB and
class D amplifiers, surround systems, and
adaptive audio.
• Positioning including MEMS IMUs and
GNSS receivers.
• Wireless connectivity for broadcast
signals, Bluetooth, near-field connectivity,
and Wi-Fi.
More connections
IVI processor
A connected vehicle has been defined as
one equipped with Internet connectivity and
able to send and receive data. Today, that’s
only the beginning. IVI MCUs are required
to manage connections to Wi-Fi (including
the creation of local networks), smartphones,
wireless sensors, GPS, and other devices.
Various levels of connectivity are emerging
that support value-added services for drivers
and passengers. For a deeper dive into these
developments, check out the FAQ on “What
A typical IVI MCU, like the one illustrated
in the Control Unit in the center of Figure 2
above, includes a 32-bit RISC processor with
enhanced security features, cryptographic
accelerators, and improved flash memory
capability up to 500 kcycles with 15 years
of data retention. To improve performance,
it uses the Thumb-2 instruction set that’s an
enhancement to the 16-bit Thumb instruction
set. Thumb 2 adds 32-bit instructions that can
be freely intermixed with 16-bit instructions
Figure 2. The functions of an IVI system can be monitored and
coordinated with a centralized control unit (STMicroelectronics).
screens, software-defined controls, and
voice commands. In advanced designs, the
domain controller can also monitor the driver’s
attention and focus on driving. A variety of
MCUs will be required to support audio and
video interfaces for drivers and passengers
and to add new comfort and entertainment
applications as well as advanced driver
assistance capabilities. The trend is toward
personalization and flexibility through
software-defined functions that are replacing
centralized architectures with distributed
computing capabilities, more memory, and
faster connectivity (Figure 1).
Cars are becoming independently aware
of passengers. Advanced systems have been
proposed using millimeter wave (mmwave)
radar to detect and categorize passengers
versus packages and other objects in the cabin,
enabling the IVI to be more proactive and
interactive. IVI systems are also available that
support biometric authentication, like facial
recognition or fingerprint scanning, to provide
a more secure and personalized experience.
Biometrics can also be used to limit access
to specific features and prevent theft. Driver
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08 • 2023
DESIGN WORLD — EE NETWORK
19
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
in a program and enables an MCU with
Thumb-2 to cover the full functionality of
the ARM instruction set.
The use of two CPUs in lockstep mode
plus error detection in sensitive memories
and hardware logic provides strong and
multiple protection mechanisms for high
detection coverage and supports the
development of highly secure software.
Two series communication slave
interfaces are compatible with ISO/IEC
7816-3 and a single wire protocol (SWP)
that supports near-field communications
with smart cards and similar devices in
secure applications. Other communications
interfaces include a master/slave serial
peripheral interface (SPI) and I2C. The slave
SPI operates up to 48 MHz, and the master
is rated up to 15 MHz. The I2C interface
operates at up to 1 Mbit/s.
Multiple timers are integrated
including a permanent timer (PMT) with
a count capability in low-power mode,
three general-purpose 16-bit timers, and a
watchdog timer.
Security is a primary concern and
includes hardware accelerators and
advanced cryptographic functions like:
• Platform and flash memory loader
security certification target under
a Common Criteria framework that
enables designers to specify security
functional requirements (SFRs) and
security assurance requirements (SARs).
• The 3-key triple DES accelerator
(EDES+) peripheral supports a data
encryption standard (DES) hardware
security-enhanced accelerator.
• A NESCRYPT (NExt Step CRYPToprocessor) light low power (LLP)
cryptoprocessor efficiently supports the
public key algorithm.
• The advanced encryption standard
(AES) and SM4 security-enhanced
accelerators ensure secure and fast AES
and SM4 implementations.
• 16- and 32-bit cyclic redundancy
check (CRC) calculation blocks that
support standards like ISO 13239 and
IEEE 802.3.
• An active shield that protects
against faults caused by probing or
manipulating signals and adding or
removing features from the MCU.
• A true random number generator
(TRNG) for producing random numbers
instead of a pseudo-random number
generator, which uses deterministic
algorithms to produce a sequence of
numbers that appear random but are not.
IVI SoC
To support IVI systems, SoCs have been
developed with multiple cores like a 32-bit
ARM multicore processor with an out-oforder superscalar pipeline running at up
to 2.5 GHz that can support concurrent
applications. Additional lower power
cores are included to support real-time
interrupt-intensive activities, and GPUs are
included for high-performance HMIs. Some
IVI SoCs also include a high-performance
DSP for applications like voice recognition,
surround-view stitched video, and various
software-defined functions.
Entertainment is an important aspect
of IVI systems, and it's common for the
display subsystem to simultaneously
support multiple 1080p screens with
higher resolutions and larger displays in
advanced systems. IVI SoCs also include
hardware accelerators that can support
high-def video decoding and encoding.
Audio processing is an important aspect of
the info and ‘tainment functions including
speech processing, voice recognition,
active noise canceling and multi-zone
audio (Figure 3).
Safe and secure
With increasing connectivity and OTA
updates, security is critical to IVI system
implementations. The SOC needs
to address cybersecurity threats and
vulnerabilities. Several standards have
been developed to ensure the safety and
security of IVIs including:
ISO 21434 is specific to cybersecurity
in the automotive industry. Coverage
includes the design and development of
secure systems in vehicles. It addresses
management of software updates and
the use and management of open-source
software.
ISO 21448 focuses on the safety
of the intended functionality (SOTIF) in
automotive systems. Coverage includes
Figure 3. An IVI SoC can combine many
diverse functions into a single device
(Texas Instruments).
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DESIGN WORLD — EE NETWORK
08 • 2023
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AUTOMOTIVE INFOTAINMENT
the safety of advanced driver assistance
systems (ADAS) and autonomous driving
systems (ADS). It also addresses the need
to identify and mitigate cybersecurity
threats and vulnerabilities.
ISO 26262 includes guidelines related
to functional safety in vehicles and the
development of safe systems, including
the identification of hazards and the
implementation of measures to mitigate
them. Management of software updates is
also covered.
KOA_ConceptCarAd_EE_7_23.qxp_Layout 1 6/28/23 2:27 PM Page 1
Summary
IVIs are important systems in modern
vehicles providing drivers with information,
passengers with entertainment plus
information, and are beginning to monitor
driver attention and awareness.
References
Automotive and Infotainment
Technologies, Mistral
https://www.mistralsolutions.com/blog/
automotive-infotainment-overview/
Designing In-Vehicle Infotainment Systems
in 2023, Tremend
https://tremend.com/blog/automotive/
designing-in-vehicle-infotainmentsystems-2023/
From
Concept to Reality
Bring Your Designs to Life
with our Passive Components
How do MCUs support automotive
infotainment systems, Infineon
https://www.infineon.com/cms/en/
applications/automotive/infotainment/
Infotainment Head Unit,
STMicroelectronics
https://www.st.com/en/applications/
in-vehicle-infotainment-ivi/infotainmenthead-unit.html
Today’s high-end infotainment soon
becoming mainstream, Texas Instruments
https://www.ti.com/lit/wp/spry261/
spry261.pdf
Thin Film Resistor
for Automotive
RN73H
• Improved moisture
resistance by special
protective coating
• High precision
tolerances
±0.05% ~ ± 1%
• High performance
TCR ±5 ~ ±100ppm/°C
Surge & Pulse
Precision Resistors
SG73P/S
• Pulse withstanding;
down to
±0.5% tolerance
• Endures the ESD
limiting voltage
• Resistance range:
1 ~ 10MΩ
High Voltage Resistor
for Automotive
HV73V
• Maximum working
voltages from
350V ~ 800V
• Resistance range:
10K ~ 51MΩ
• Tolerances:
±0.5% ~ ±5%
Anti-Sulfur
Resistors - RT
• Broad family of
resistors with
excellent anti-sulfur
characteristics
• Passes ASTM-809
anti-sulfuration testing
• Excellent heat
resistance and
environmental
resistance
To make your design a reality, check out our products!
www.KOASpeer.com
DESIGN WORLD — EE NETWORK
21
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Advancing automotive networks:
robust ESD protection for
Ethernet applications
ESD protection devices act in synergy with the rest of the circuitry
resulting in a robust system against destructive ESD and EMC.
Andreas Hardock, Nexperia
ETHERNET
technology
has
emerged as a robust and reliable solution for
data communication in various industrial and
computing applications. While its adoption
in the automotive sector has been relatively
limited, automotive Ethernet is gaining
momentum due to its ability to deliver fast
and resilient data transfer. With its high
bandwidth, flexibility in bus topologies,
and support for multiple electronic control
units (ECUs), Ethernet technologies are
strong contenders for advancing automotive
networks from domain-based to zonal
architectures. This article delves into the
requirements and properties of modern
semiconductor electrostatic discharge (ESD)
protection devices, specifically in connection
with the 100BASE-T1 and 1000BASE-T1
standards, and explores how these devices,
when synergistically integrated with the rest
of the circuitry, contribute to the creation
of a robust system that defends against
destructive ESD events and electromagnetic
compatibility (EMC) issues.
Standards and testing
Ethernet solutions have a long-standing
presence in industrial and computing
applications. However, the automotive
industry has traditionally been less inclined
to embrace this technology. Nevertheless,
recognizing the immense potential of
automotive Ethernet, the One Pair
Ethernet Network (OPEN) Alliance
committees, along with the Institute of
Electrical and Electronic Engineers (IEEE),
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DESIGN WORLD — EE NETWORK
Figure 1: Typical
configuration of Ethernet
nodes in a modern vehicle.
have collaborated to develop standards
specifically tailored to meet the unique
demands of the automotive sector. In 2016,
the 100BASE-T1 and 1000BASE-T1 standards
were drafted, and in more recent years, the
OPEN Alliance has been actively working
on developing two additional standards,
namely 10BASE-T1s and MGB-T1. The
OPEN Alliance, comprising multiple technical
committees, strives to standardize Ethernetbased technologies in the automotive
market. At the same time, the IEEE has taken
charge of the 100BASE-T1 and 1000BASE-T1
standards, addressing automotive
requirements, particularly those related to
EMC. This collaborative effort ensures that
Ethernet technology in the automotive
domain aligns with industry-wide standards
and undergoes rigorous testing to ensure
compliance and performance.
ESD protection requirements for
100BASE-T1 and 1000BASE-T1
Automotive applications greatly benefit
from the flexibility offered by Ethernet
connections. Star topologies can employ
these connections, where a switch serves
as a central point, interconnecting multiple
domains such as Advanced Driver Assistance
Systems (ADAS), infotainment, and more.
Alternatively, Ethernet can be utilized in a bus
topology, similar to the traditional CAN and
FlexRay applications (Figure 1).
Notably, the standardization of
Figure 2: Two Ethernet nodes are connected using an unshielded twisted pair (UTP)
08 • 2023
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ESD PROTECTION REQUIREMENTS
Figure 3: Circuitry of the 100BASE-T1 and
1000BASE-T and the ESD performance of the
ESD device.
applications, these specific requirements
create a unique set of criteria, as shown in
Table 1.
Additional ESD testing for OPEN
Alliance ESD protections
100BASE-T1 and 1000BASE-T1 employs
unshielded twisted pair (UTP) cables (Fig. 2),
commonly used in the automotive industry
due to their widespread availability and
cost-effectiveness. However, UTP cables
present challenges related to EMC behavior,
particularly regarding electromagnetic
interference (EMI) in bundled cable
configurations.
In a modern vehicle, numerous electrical
units are interconnected by hundreds of
meters of cables, ranging from simple climate
control units to powerful generators. These
cables are often bundled together, increasing
the risk of electromagnetic interference (EMI)
between them. Extensive investigations have
revealed that, in worst-case scenarios, this
EMI can induce peak voltage amplitudes of
up to 100V in unshielded twisted pair (UTP)
cables. This poses a challenge as stable data
transfer is required during normal operation,
highlighting the need for robust Ethernet
circuitry to withstand these EMC issues.
The circuitry of each node in the
Ethernet system, standardized by the
OPEN Alliance, includes a common
mode choke (CMC) to filter out unwanted
common mode noise that couples in the
UTP. In conjunction with common mode
termination, the CMC addresses these EMC
concerns. The properties of the CMC for
100BASE-T1 and 1000BASE-T1 are defined
in the CMC Test Specifications specific to
these standards. Apart from its filtering and
EMC characteristics, the CMC also plays a
crucial role in electrostatic discharge (ESD)
protection, which will be discussed in the
following section.
From the perspective of ESD protection
devices, there are several important
considerations. Firstly, considering the
potential electromagnetic noise on the UTP,
the ESD device should remain inactive within a
voltage range of up to 100 V. In terms of ESD
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In addition to the requirements outlined in Table
device parameters, the triggering threshold
1, more tests need to be performed to ensure the
for the ESD device is set above
effectiveness of OPEN Alliance ESD protections.
100 V, as shown in Figure 3 of the Transient
ESD vendors typically conduct these tests, and
Voltage Suppressor (TVS) graph. While
their results can be valuable for hardware design
this voltage threshold may seem high, it is
engineers.
important to note that the specific circuitry
When it comes to 100BASE-T1 and
configuration, including the CMC, provides
1000BASE-T1, the tests are quite similar,
robust protection
for the physical
Table 1. Specification of the ESD protections for 100BASE-T1 and
layer (PHY)
1000BASE-T11
components,
such as highParameter
Target Value
performance
cameras and
Working direction
bi-directional
displays.
Secondly,
Operation voltage (VDCmax)
≥ 24 V
the ESD
protection device
ESD trigger voltage
≥ 100 V
is subjected to
rigorous testing
+/- 15k V contact discharge for
unpowered device using discharge
to ensure its
module according to ISO 10605
robustness, with
(discharge storage capacitor C =
requirements
150 pF and discharge resistor R =
of withstanding
330 Ω
ESD robustness
15kV ESD
discharges for
Minimum number of
a minimum of
discharges
> 1000
1000 cycles.
This stringent
TLP characteristic according
requirement
to [2]
I/V characteristics
underscores
the criticality
Table 2. Additional ESD testing for OPEN Alliance standards
of reliable
operation for
Test
Purpose
Ethernet-based
applications in
S-Parameters
Signal Integrity
the demanding
automotive
Damage from ESD
Signal integrity after ESD events
environment.
Combined
Evaluation of ESD current which
with the 24
ESD Discharge
flows into the PHY during an ESD
V operating
Current
event
voltage, similar
Robustness against external EM
to that of CAN
RF Clamping
08 • 2023
noise
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
but they have different pass criteria. The
first two tests focus on the impact of the
ESD protection device on signal integrity
(SI) in automotive Ethernet applications.
It is important to assess how the device
affects SI by measuring insertion loss
(IL), return loss (RL), and common mode
rejection ratio (CMMR), as shown in
Figure 4. To ensure compliance, specific
limits for these parameters are
provided in the "Specification of the
ESD protection for 100BASE-T1 and
1000BASE-T1" document.
In the automotive domain,
there is a new factor to consider —
the ESD discharge current, which
quantifies the current flowing into
the PHY during an ESD event. It
is crucial to evaluate this current
to ensure proper protection.
Additionally, RF clamping is
employed to simulate the noise on
the UTP, taking into account the >
100 V requirement.
By conducting these additional
tests, engineers can gain a deeper
understanding of how the ESD
protection devices perform in
terms of signal integrity and current
flow, ensuring the robustness and
reliability of the Ethernet system in
automotive applications.
Alliance (OA) approach demonstrates
that having the ESD device close to
the connector results in the lowest
current density at the PHY location.
Consequently, the entire circuitry exhibits
optimal ESD performance for the system.
It's important to grasp the role of
the CMC in reducing ESD stress for the
PHY. To understand this, let's examine
the behavior of the CMC under pulsed
conditions, as depicted in Figure 6. We
utilize the transmission line pulse (TLP)
method to illustrate the blocking and
saturation phases of the CMC. When a
transient pulse, such as an ESD pulse,
heads towards the CMC, it initially blocks
the current for a specific period of time
during the blocking phase (phase II), with
Optimal placements, routing,
and layout techniques
Let's dive into the crucial aspects
of placing, routing, and laying out
the ESD protection devices in an
Ethernet design. It's not just about
the performance of the ESD device
itself; its implementation on the PCB
plays a vital role. Figure 3 gives us
a visual representation, highlighting
the importance of placing the ESD
device at the connector. This strategic
placement ensures that any ESD
pulse is immediately clamped down
to ground right at the connector,
safeguarding the entire circuitry,
including the CMC, CMT, and PHY.
For a tangible demonstration of the
significance of placement, refer to
Figure 5.
In Figure 5, a field scan of the
Ethernet circuitry during an ESD
event reveals areas of high current
density, indicated by red. The OPEN
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DESIGN WORLD — EE NETWORK
Figure 4: S-parameter results for an ESD protection device for
1000BASE-T1, including the limits in yellow.
08 • 2023
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ESD PROTECTION REQUIREMENTS
Table 3. Ranking of the different rounting options with regard to ESD and SI
SOT23
Signal Integrity
A
B
C
A
B
↓
↑
↑
→
↑
↑
ESD
↓
Figure 5: Field scan of the Ethernet circuitry during an ESD event
the peak (in phase I) being a measurement
artifact. The duration of the blocking
phase depends on the voltage level of the
pulse ­­the higher the voltage, the shorter the
blocking phase. After the blocking phase, the
CMC enters the saturation phase (phase III),
acting as an inductor driven into saturation
by the pulse. Once saturation occurs, the
CMC starts conducting the current, leading
to a drop in voltage across it.
This intriguing finding demonstrates
that when an ESD pulse approaches the
100BASE-T1 or 1000BASE-T1 circuit, the
CMC effectively blocks the current for the
first few nanoseconds. Simultaneously, the
voltage across the ESD protection device
increases. When the voltage reaches the
trigger level, typically around 140 V (Figure
3), the ESD device clamps the ESD pulse to
ground. As a result, the voltage across the
entire circuit drops to the clamping voltage
of the ESD device, typically ranging from
30 to 40 V (see TLP plot in Figure 3).
This showcases the synergistic effect of
combining a high-trigger ESD protection
device with a CMC during ESD events.
It's worth noting that a CMC with an
inductance in the range of approximately
100µH exhibits sufficient blocking behavior,
which is already covered by the CMC
specification.
ESD protection devices are typically
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DFN1006BD
available in various packages. One
widely used package is the SOT23, a
common and established
choice in automotive
applications. Another
option is the DFN1006BD
(SOD882BD), a leadless
package. Figure 7
illustrates different
options for routing
the differential lines to
and from the package,
and their rankings are
provided in Table 3.
When routing
the ESD packages, it's
generally advisable to
keep the routes straight,
avoiding any stubs or
bends. Specifically, for
ESD considerations, the
traces of the differential
lines should pass over the
pad of the ESD device,
as depicted in options
[A] and [C] for SOT23, as
well as for DFN1006BD
in option [A]. It's crucial
to avoid stubs and ensure
that the impedance of
the differential lines remains at 100Ω
to maintain signal integrity (SI). This
08 • 2023
↑
↑
↓
can be achieved by keeping the lines
separated. For SOT23, options [B] and
[C] are preferable, while for DFN1006BD,
option [A] is the recommended choice.
As a general rule, try to minimize
unnecessary layer changes to achieve
optimal signal integrity. Layer changes will
inevitably impact SI and electromagnetic
compatibility (EMC). If you must change
layers, route the signal over the pad of the
ESD device, as shown in Figure 8 (left and
right). Avoid routing signals via stubs, as
depicted in Figure 8 (middle).
By following these guidelines for
placement, routing, and layout, you can
effectively enhance the performance,
reliability, and protection of ESD in your
Ethernet design.
Figure 6: Current and voltage response of a typical
CMC for 1000BT1 applications based
on TLP measurements
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Figure 7: Routing
options for SOT23
and DFN1006BD
(SOD882BD)
Final thoughts
The article emphasizes the unique circuitry and ESD protection
requirements in 1000BASE-T1 and 100BASE-T1 applications. It
highlights the strong synergy between ESD protection devices
and the blocking capability of the CMC, resulting in a highly
robust Ethernet system that effectively combats EMC noise
and ESD. The significance of positioning the ESD protection
directly at the connector is underscored through an EMI scanner.
Additionally, it should be noted that discussions within the OPEN
Alliance committees are underway for an additional standard,
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DESIGN WORLD — EE NETWORK
08 • 2023
10BASE-T1S, which is expected to have similar requirements
regarding the high trigger voltage, given the similarity in
topology with 1000BASE-T1 and 100BASE-T1. Further research
and development in this area will contribute to the continuous
improvement of ESD protection solutions and their role in
supporting automotive Ethernet applications.
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TRACTION MOTORS
What is a traction motor
and when should you use one?
Traction motors are optimized for locomotives, EVs, elevators, and other
situations where high torque at start-up and low speed is needed.
Bill Schweber
MOTORS
are essential
components
in several applications, powering
equipment in many industries. In simple
terms, a motor is a device that converts
electrical energy into mechanical energy,
generating motion or providing rotational
force. Different types of motors have
variations in design, each with specific
features such as power, speed, torque,
size, and control precision.
A traction motor is an electric motor
optimized for drive or propulsion, where
high torque and low speed are required.
These motors are often used in electric
vehicles (EVs), locomotives, elevators, and
other equipment.
Traction motors can be designed as
DC or AC motors, including synchronous,
asynchronous (induction), and multiphase
AC motors. Modern motor-control
electronics tend to favor multiphase AC
drives. However, AC induction motors and
permanent-magnet synchronous motors
(PMSM) are most commonly used in EVs.
Each manufacturer has engineering and
market reasons for choosing a specific
motor arrangement.
The type should be carefully
assessed to best fit an application based
on design, performance, reliability, and
cost. Additionally, the motor’s physical
structure should be evaluated, including its
lamination layout, windings arrangement,
and the amount of copper wiring and
iron used. The electrical schematic of a
traction-optimized motor and another
type might be the same on paper, but the
physical details differ.
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Figure 1. This family tree is focused primarily on AC motors and shows the many variations
in use (Image: ibiblio.org).
Do your due diligence
Motor design is continually evolving,
driven by demands for increased efficiency,
improved performance, and reduced costs
and environmental impacts. Advances
in motor-related control algorithms and
power-switching devices mean that
previous limitations and conventional
wisdom may no longer apply.
A motor that was once an ideal choice
for an application might be outdated,
so design engineers must do their due
diligence.
For example, the classic brushed motor
08 • 2023
is generally only useful for low-end toys
or products requiring little motion control.
This type of motor is typically avoided in
advanced applications. However, a recent
design of a medical infusion pump shows
that a modern brushed motor is an ideal
choice to meet its performance objectives.
Given today’s advances, it’s no longer
appropriate to associate one type of
motor with a specific application. Motors
come with deceptively simple electrical
schematics that rarely exemplify their full
features and capabilities. Unfortunately,
motor family trees are unreliable as shown
in Figures 1 and 2 because they only focus
DESIGN WORLD — EE NETWORK
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Figure 2. Another family tree shows less detail
but gives comparable attention to both AC- and
DC-powered motors (Image: Monolithic Power
Systems).
on the motor’s design and fail to include its
applications.
Ensuring the ideal choice for an application
means considering the motor’s features
(including its efficiency, capacity, durability, and
control capabilities) and its compatibility with
other system components (such as the size,
weight, and torque requirements). Additional
factors such as maintenance needs, costeffectiveness, and regulatory or environmental
considerations should be evaluated before
deciding on a motor.
Choosing a traction motor
Traction motors differ significantly from
industrial motors, including those with similar
power ratings. Whereas industrial motors
usually power equipment or machinery in
enclosed spaces and within a rated or limited
range of operating conditions, traction motors
are designed for mobile applications.
Traction motors are critical for converting
electrical energy into mechanical energy to
propel an application (such as an electric
vehicle) forward.
For this reason, they require efficient power
conversion, including:
• High torque for start-up acceleration
• Low speed for the general operation
• Low torque for high-speed cruising and
frequent starts/stops
• The capacity and reliability for a range of
operations, particularly in terms of speed
(Figure 3)
Overall, traction motors must
withstand a high rate of acceleration and
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DESIGN WORLD — EE NETWORK
deceleration, with variations in speed and
torque.
In most installations, traction motors
also lead a “hard life” with respect to
shock and vibration, temperature extremes,
exposure to dirt and debris, and start /stop
operation. They can span tens to several
thousand horsepower (roughly ten to several
thousand kilowatts). The lowest value
might be for an electric forklift truck, which
only operates at low speeds and where
acceleration is not an issue.
An EV and full-power railway locomotive
require greater power. A typical electricvehicle traction motor is rated at around 200
kW. Of course, these higher power levels
necessitate heavy electrical conductors,
strong cable portions, and connectors that
can endure.
locomotives, urban light-rail vehicles (LRVs or
trams), and suburban LRVs.
Traction motors are also finding use
as electric drives in heavy construction
equipment. To power such heavy-duty
equipment, these motors are similar to a
diesel-electric locomotive with an onboard
fuel tank and a fixed-speed diesel engine
— driving a generator to power the various
motors (Figure 4).
Most notably, traction motors have
become a popular choice for use in hybrid
and electric vehicles. In terms of EVs, traction
motors offer several advantages. Since they’re
designed for high efficiency, they can optimize
the conversion of electrical energy from a
vehicle’s battery into mechanical energy,
maximizing its range and performance.
This has spurred R&D in mid-range
traction motors and their driver circuits and
components. For instance, traction motors can
integrate with a vehicle’s control system (such
as its sensors, motor controllers, and software
algorithms) to ensure precise speed, torque,
and power output control.
What’s more: traction motors can
incorporate regenerative braking capabilities,
allowing them to act as a generator during
deceleration. This feature lets the motor
recover and convert a portion of a vehicle’s
kinetic energy back to electrical energy, which
can be stored in the battery for later use.
AC versus DC motors
In the early 20th century, when electric
traction was first developed, DC and AC
motors were tried and tested. DC motors were
favored because they provided the necessary
torque characteristic for railway operation and
Common
applications
As traction
motors are
used to provide
propulsion,
they’re
commonly
used in railway
locomotives,
including
diesel-electric
and overhead
catenarypowered
all-electric
Figure 3. Traction motors can deliver high torque at low speeds for start-up
acceleration, along with low torque at high speeds (image: Everything PE).
08 • 2023
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TRACTION MOTORS
the same speed as its stator
rotating magnetic field.
This is not the case with
asynchronous motors, which
operate at a speed slightly
below the synchronous speed.
This speed difference, known as
slip, is necessary for the motor
to generate an induced voltage
and rotor current — creating
the torque required for motor
operation.
An advantage of the
AC motor is that it requires
zero brushes since there’s no
electrical connection between
the armature and the fields. The
Figure 4. Electric-based drivelines using traction motors are now being used in some heavy equipment, with a
armature can also be made of
diesel-driven generator as the primary electrical power source (image: ABB).
steel laminations instead of the
were easier to control then.
up and down from a primary power source,
numerous windings required
For example, the first electric motor was
such as a generator at the power plant to the
in other motors. These features make it more
the brushed DC motor. The brushes (springdesired voltage for the transmission line. But
reliable and cost-effective than a DC-based
loaded contacts) press against an armature
the availability of high-performance solidcommutator motor.
extension called the commutator (Figure
state devices, such as insulated bipolar gate
AC motors can be single or three-phase,
5). As the magnetic fields of the stator and
transistors (IGBTs, which act as fast switching
with three-phase motors used in bulk or higher
commutator fields interact, the commutator
devices) and thyristors, makes it possible to
power-conversion applications. The threerotates, and the brushes “switch” the current
step up and down DC effectively. For some
phase traction motor is controlled by feeding
direction so the field reverses and continues to
applications, such as long-transmission lines,
in three AC currents, which cause a machine
push the rotor.
DC has advantages.
to turn. The three phases are most easily
The high current results in strong
provided by an inverter that supplies the three
Understanding AC-driven motors
magnetic fields and high starting torque
variable-voltage, variable-frequency (VVVF)
There are two types of AC motors:
(turning force), so it’s well-suited for starting a
inputs, with voltage and frequency variations
synchronous and asynchronous (induction)
heavy object like a train. Controlling the speed
electronically controlled and optimized.
motors. The synchronous motor rotates by
and torque over a wide range, however, is
The frequency of its supply determines
alternating the AC current applied to its
difficult and was done by manually switching
the speed of a three-phase AC motor. At
windings. It rotates at
resistors in and out, and in series and parallel,
the same time, the power must be varied to
to match the applied current and current to the
load, speed, and torque objectives.
By the ’80s, power electronics had
significantly progressed, and three-phase AC
motors became a more efficient alternative in
most cases. They’re far simpler to construct,
require no mechanical contacts (brushes) to
wear or fail, and are lighter than DC motors of
the same power output.
Today, AC motors can be processor controlled
with sophisticated algorithms that improve
performance, control adhesion and slippage,
and offer several operational advantages.
They’re also more reliable and easier to
maintain than DC motors. For this reason, most
new systems use AC-driven motors.
Although it should be noted that while
AC became the preferred choice for decades),
advances in electronics provide greater
Figure 5. The classic DC-driven motor requires no electronics, as it self-communicates the current via
the conductive brushes which alternate the current’s direction and thus reverse the magnetic field
freedom of choice. AC was once easier to step
(Image: The Railway Technical Website).
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08 • 2023
DESIGN WORLD — EE NETWORK
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AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
match the load and torque requirements.
Modern electronics, such as the IGBT, make
the asynchronous AC drive practical for
applications, such as EVs (Figure 6).
Adding permanent magnets
Permanent magnet (PM) motors are electric
motors that use magnets in the rotor instead of
electromagnets. The interaction between the
PMs and the electromagnetic field produced
by the stator windings generates the required
torque for motor operation.
The PM motor is a three-phase AC
synchronous motor, where the typical
squirrel cage construction is replaced by
magnets fixed in the motor. It requires a
complex control system, but it can be up
to 25% smaller than conventional threephase motors with the same power rating.
The PM design provides lower operating
temperatures, so cooling requirements are
simplified.
Some traction motors use PMs. For example,
Tesla uses a combination of motors,
including PMs, because the vehicle space is
limited (Figure 7). A few of Europe’s 25 AGV
high-speed train sets and LRV trams also
rely on PM motors, such as those in France
and Prague. The reduced size is particularly
attractive in low-floor LRVs where hub motors
can be combined in a compact bogie.
Figure 6. The modern 3-phase AC motor is controlled by three variable-voltage,
variable-frequency (VVVF) inputs; while complicated, it offers many operational benefits
(Image: The Railway Technical Website).
Mounting the motor
With few exceptions, a traction motor is
mounted on or in part of the wheel axle that
it’s driving. It’s typically a direct-drive system
with minimal or no intervening gearing. This
means a reduced parts count in an application.
A traction motor’s low weight and small size
are also advantages.
In most locomotives, there’s only one
motor per axle on the train bogie (the bogie
or “truck” is the chassis or framework that
carries a wheelset). One of the challenges in
railroad design involves offsetting the weight
of the motor on the un-sprung wheel axles and
placing it on the sprung part of the bogie for
better balancing and handling (Figure 8). For
lighter-service engines, only one axle is
powered.
In other applications, one motor powers
both axles of the bogie, referred to as
a mono-motor bogie. The ideal design
depends on the vehicle size, weight
restrictions, required speed, and other
factors.
At the controls
Controllers or inverters play a critical role
in controlling the operation of a traction
motor, which is responsible for driving
a vehicle’s wheels or propulsion system.
Most are custom designed to meet
application characteristics and ensure
optimal performance. Take an electric
vehicle, for instance, where a percentage
point or two in efficiency is critical due to
cooling needs and range objectives.
However, there are certain standard
power and controller units for traction
motors, depending on the make. CurtissWright recently introduced 100-800 VDC
Figure 7. The choice of traction motor involves balancing many factors and tradeoffs, and a single vehicle may input/420-kW (at 700 VDC) inverters for
single-motor (CWTI-S420) or dual-motor
use different motor types for its front and rear axles (Image: Tesla Motors).
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DESIGN WORLD — EE NETWORK
08 • 2023
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TRACTION MOTORS
(CWTI-D420) applications in electric busses, hybrid vehicles, and dieselelectric off-road vehicles (Figure 9).
For flexibility, both models can feed power to a range of motor
technologies, including AC induction, PM motors, and interior
permanent-magnet (IPM) types. IPMs incorporate permanent magnets
within the rotor core, which creates a magnetic field that interacts with
the stator windings to generate torque for motor operation.
According to Curtiss-Wright, its advanced motor-control software
runs adaptive tuning to get two percent higher levels of efficiency
between the inverter and motor. These traction inverters offer shortcircuit and fault protection, as current and temperature are measured
directly on the IGBTs. The inverters also use vehicle-grade components
certified to AEC Q-100, 101, and 200
standards, adhering to ISO 26262
— an international safety
standard for developing
electrical and electronic
systems in vehicles.
Figure 8. The traction motor
is usually designed to mount
on or immediately adjacent
to the axle it is driving
(image source: The Railway
Technical Website).
Figure 9. This power inverter
(dimensions shown are in
millimeters) can deliver up to
420-kW from 700 VDC inverters
electric busses, hybrid vehicles,
and diesel-electric off-road
vehicles; it embeds advanced
algorithms to optimally drive
different traction-motor types
with high efficiency and safety
(Image: Curtiss-Wright Corp.).
Conclusion
Traction motors are an important class of electric motors optimized for
high torque at start-up and low speed. They can power small movers
such as forklifts and large systems such as all-electric locomotives and
EVs.
With the increased development of consumer electric vehicles,
there are several advances in motor performance and design. Modern
electronics have made the older brushed DC motor less attractive,
replacing them with AC-based motors using IGBTs for power switching
under processor control. The ideal choice depends on the application
space, design, power requirements, and overall project budget.
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Testing batteries
for an evolving world
Battery testing enables vehicle manufactures, owners, and researchers
to make informed decision, optimize vehicle performance, and enhance
overall user experience.
Russ Gaubatz, EA Elektro-Automatic
DEMAND
for electric vehicles is amping
up. Every one of these vehicles
needs large batteries, and the industry is responding by building
plants. Energy.gov forecasts that by 2030 electric vehicle battery
manufacturing capacity in North America will grow 20 times,
eventually supporting 10-13 million electric vehicles per year.
Testing those batteries is a critical part of battery
production. The first reason for testing is for safety. Due
to a chemistry that supports runaway thermal events and
sustains fire, Lithium-ion (Li-ion) batteries are dangerous.
After exposure to vibration and high ambient temperatures,
even small manufacturing anomalies can lead to catastrophic
failure. Recently, Li-ion scooter batteries have been blamed
for devastating building fires, and Jaguar Land Rover issued a
recall of more than 6000 vehicles after eight customer fires were
caused by battery thermal events.
Additionally, buyers want to know exactly how far they can
34
DESIGN WORLD — EE NETWORK
08 • 2023
drive on a charge. Battery testing can simulate the load placed
on a battery during driving conditions and predict a vehicle’s
driving range.
Battery testing is getting harder
While battery volume is rising, testing is becoming more
challenging. As vehicle buyers demand more storage for greater
range, the capacity of batteries is increasing. What’s more, pulse
testing requires exponentially more current than the battery’s
ampere-hour rating. Given all this current, safety becomes
paramount. Fire is a real risk caused by voltage or current
exceeding the limits of the battery cells’ internal structures during
charging or discharging.
For example, if a technician forgets to set a voltage limit
during a constant current discharge, then the temperature
of a battery cell could rise from 23 to 400 degrees Celsius in
milliseconds. Catastrophic explosions are also possible. In fact,
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BATTERY TESTING
Figure 1. An ATE system for battery testing
includes bidirectional power supplies,
a controller, safe connectors, CAN Bus,
an industrial PC, software, a software
environmental chamber, and a chiller.
some manufacturers have built explosion-proof
rooms for their automotive battery testing.
Add to high power the need for
throughput — testing multiple batteries at the
same time — and the battery automated test
equipment (ATE) must be capable of sinking
and sourcing many kWs of power. In some
facilities, there isn’t enough space on the
production floor to add multiple racks of the
power supplies used in the test system.
Higher voltages are another challenge for
testing. To reduce the weight of conductors
in the vehicle and to reduce heat caused
by electrical resistance, vehicle drivetrain
voltages have climbed to 450 V and now
are in the 800 V range. While test engineers
can add more power supplies to increase
the power of their test systems, they cannot
change the maximum voltage rating of their
test systems. Current EV modules require
testing at up to 900 V.
How a battery test system works
Figure 1. An ATE system for battery testing
includes bidirectional power supplies,
a controller, safe connectors, CAN Bus,
an industrial PC, software, a software
environmental chamber, and a chiller.
The main production-line tests for battery
manufacturers include:
• Battery cycle test
• Drive cycle simulations
• Insulation resistance
• DCIR testing
To perform these tests, test systems use
multiple bidirectional power supplies in parallel.
A DC bidirectional power supply operates in
quadrants I and II, meaning it is capable of both
sourcing and sinking DC power.
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a lower voltage. This allows the power supply
to maintain a constant power load across that
load’s full power operating range.
The red line in Figure 2 shows the
output of a true auto-ranging power supply.
Without switching ranges, the power supply
can output from 500 V to 166.6 V while
maintaining 5 kW of constant power. Without
this feature, the wattage of the power supply
must be oversized, or double the number of
power supplies will be required, and therefore
the test system will be more costly.
Figure 2: Output of a true auto-ranging
power supply
As the power levels in batteries rise, one
of the challenges is testing across increasingly
wide ranges of power and voltage. In the plant’s
research lab, technicians may test individual
cells at 2.5 to 4.2 V, test modules at 420 V, and
test complete automotive battery packs at 840
V. True auto-ranging helps engineers test from
system level all the way down to cell level using
one power supply system.
It is not unusual for engineers to be
confused when selecting a power supply
system. Looking at the batteries they expect to
test, they think they need a 30-kW system. But
they forget the formula P=IV, which says at 1500
V the highest current a 30-kW power supply can
output will be 20 A. If the test engineer needs
the power supply to output more current, say 60
A, then they need to lower the voltage or buy a
test system offering 90 kW.
In conventional bidirectional power
supplies, two operating ranges are supplied,
a high and a low. These are shown as
rectangular boxes in Figure 2. As the test
voltage rises or falls, a technician may need
to stop the test and
manually switch ranges
on the power supply.
Some battery
tests require a
supply of constant
power while varying
current or resistance.
A programmable
power supply with
a conventional
rectangular output
will supply maximum
power only at the
point of maximum
current and maximum
voltage. In contrast,
some power supplies
have a feature called
auto-ranging. The
Figure 2: Output of a
power supply will
true auto-ranging power
automatically output
supply.
more current when
the load operates at
08 • 2023
DESIGN WORLD — EE NETWORK
35
AUTOMOTIVE & TRANSPORTATION ELECTRONICS HANDBOOK
Slew rate
Slew rate is an important consideration
for automotive battery drive-cycle or
pulse-test testing, during which the
output voltage or output current changes
frequently. The slew rate is the speed at
which an output changes from its current
state to its programmed state.
The faster the slew rate, the squarer
the pulses in the output, which allows for
more precise testing. The consequence
of this is that power supplies with a slow
slew rate cannot accurately measure the
driving distance of a battery. If the test
system has a fast slew rate, the more
accurate test may result in publishing a
longer driving range, which is supremely
important to consumers.
Data acquisition speed
During production testing, the battery
management system (BMS) reports
measurements to the test system.
Temperature, current, and voltage are
recorded about once a second. The
purpose of production testing is to
validate key parameters, once a second
is sufficient.
Battery research, on the other
hand, requires more complex testing.
Engineers need to verify that the BMS
is reporting accurately, understand the
health of individual cells, and check the
connections between components. On
a vibration table, an intermittent event
resulting from a broken connection
may last only a millisecond. If the data
acquisition speed is too slow, then
testing may miss such events.
Slow data acquisition speed may
also introduce imprecision. This can show
up when testing identical batteries with
a drive profile test. The result for the first
battery may be 400 miles, and the result
for the second battery may be 405 miles.
Actually, the driving ranges are essentially
identical, but a slow data acquisition rate
limits the accuracy of the testing. This
can happen when a company buys a test
system made for production and uses it
in the lab.
Figure 3. Considerations for battery
test systems include how much space is
available on the production floor. Some
systems, like the EA 10300 Series from
EA Elektro-Automatik shown here, use
SiC technology to offer a power-dense
300 kW in a single rack.
The above considerations will help
engineers prepare for a future where
automotive batteries are a dominant
aspect of automotive manufacturing.
According to EYs Mobility Consumer
Index, more than 50% of people
planning to buy a car will choose either
a fully electric, plug-in hybrid, or hybrid
vehicle. Fast, accurate, and economical
battery testing is necessary to anticipate
consumer demand.
Figure 3. Considerations for battery
test systems include how much space is
available on the production floor. Some
systems, like the EA 10300 Series from
EA Elektro-Automatik shown here, use
SiC technology to offer a power-dense
300 kW in a single rack.
36
DESIGN WORLD — EE NETWORK
08 • 2023
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Automation & Transportation Electronics Handbook • August 2023
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