PRODUCT NEWS
DESIGN CHALLENGES
REO
OVERCOMING POOR POWER QUALITY IN SMALL SPACES
to supress EMI. EVs, much like petrol
ICE vehicles, feature an inverter and a
DC-DC converter, using high frequency
switching, to manage power conversion.
By using high frequency components like
REO’s transformers, filters and choppers,
engineers can protect any sensitive
semiconductor power electronics in the
vehicle.
Despite being invented around the same
time as the production automobile,
electric vehicles (EVs) have only become
commercially viable in the last decade. So,
while internal combustion technology has
undergone a century and a half of design
refinement, engineers now face several
design challenges while developing the
next generation of EVs, as Steve Hughes,
managing director of electric vehicle power
quality specialist REO UK, explains.
Soon, all cars will need to be capable of
zero-emission driving. Battery-electric
and hybrid cars are leading the way to
more efficient and sustainable driving,
but automotive manufacturers are under
significant pressure to design components
as robust as those designed for internal
combustion vehicles.
Internal combustion engines (ICEs) as we’ve
known them for the past hundred years
have been chosen over alternatives like the
steam engine because they’re relatively
well-suited to powering automobiles.
Now that the environmental cost is
clear, however, the UK Government has
announced plans to stop sales of pure ICE
vehicles from 2030, with The Road to Zero
Strategy.
While sales of electric vehicles are
rising, manufacturers are profiting
and governments are considering the
burgeoning EV market, there are still
various challenges that could hamper
innovation and development in the market.
According to Toyota, the average car is
made up of 30,000 components. In EVs, the
number of components is a great deal less,
especially when considering the number of
moving parts.
To explain more clearly, for an internal-
combustion engine (ICE), there is typically
the crankshaft, fuel pumps and fuel
injectors. In addition to this, there will be
two valves per cylinder, or at least four
valves per cylinder in the latest more
economic engine designs. Outside of the
engine, there are even more moving parts
including a multiple-speed manual or an
automatic transmission.
In comparison, EVs have been created to
have the simplest architecture possible.
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Take the Nissan Leaf for example, which
has been manufactured with no clutch or
torque converter, but features a simple
reduction gearbox, with a single gear ratio
and the motor itself has just one moving
part.
While the number of components may
differ, the design principles for these
components are virtually identical. For
example, each of these parts must be
able to withstand repeated bouts of
acceleration and braking, as well as low
and high-speed driving over smooth and
rough areas. The same parts must be
able to perform in a variety of extreme
environmental conditions, from hot and
humid to cold and wet.
At REO UK, we’ve identified one of the
key constraints for EV components to be
poor power quality because of issues like
electromagnetic interference (EMI). While
electrical and electronic components
provide a much more efficient transfer of
energy, having so many parts operating
in close proximity makes the vehicle
susceptible to electrical noise.
EMI, if unaddressed can result in
overheating, efficiency losses and even
interference with the vehicle’s data
communication systems. When looking to
integrate features that can mitigate issues
like EMI, design engineers are also faced
with the problem of having the limited
space of fitting more electrical components
into a vehicle that already has high
component density.
Automotive manufacturers, as we explain
in our latest electric vehicle power
whitepaper, should look to integrate
inductive and resistive components
For example, our chokes have been
designed to eliminate electrical noise
in the inverter and can effectively store
and discharge magnetic energy from
the core. This is regardless of whether its
core is made from a ferrite, amorphous or
nanocrystalline material.
According to the Department of Energy,
petrol or diesel cars can only convert
between 14 to 26 per cent of the battery’s
energy. EVs, however, can convert up to
80 per cent of the battery’s energy. This is
because vehicles traditionally use friction
to convert mechanical braking energy into
heat and wear on the brake pads. In an
EV, braking choppers are responsible for
converting any energy created as a result
of high speed changes.
Components like inverters are also at risk
of overheating. As we’ve discussed, design
engineers are already limited on space
and so traditional air-cooling methods,
that involve using a fan to dispel any
heat generated, are not viable. Instead
manufacturers must integrate liquid-
cooling systems to manage the thermal
properties of the electrical components
while allowing them to meet the space
constraints in the vehicle.
As EVs become increasingly mainstream,
it’s important that design engineers and
automotive companies keep pace with
consumer demand and not at the cost
of reducing efficiency, by using poor
quality or the wrong components. Instead,
automotive manufacturers should look
to assemble their future models with the
latest components that address prominent
issues for EVs, like poor power quality.
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