Wireless rotary torque transducers from
Sensor Technology Ltd are at the heart of a test rig to develop next generation
technologies for electric and hybrid vehicle powertrains. With unique expertise
in the electric motors and electronics used across the key powertrain
technologies, AVID Technology relies on the innovative torque transducers as
part of an automated approach to motor characterization.
Climate
change, urban air quality and the rising cost of energy have become the
defining issues of the 21st century. With energy consumption and
exhaust emissions from vehicles and transport being significant contributors to
these issues, governments across the world are driving moves to secure a future
where the air is safe to breathe and transport is more sustainable.
In the UK
this has seen the introduction of the government’s draft clean air policy,
along with the announcement that sales of petrol-only and diesel-only vehicles
will be banned from 2040, bringing the role of hybrid and electric vehicles to
the fore. In evolutionary terms, these technologies are still in their infancy,
and this is where AVID Technology comes in.
Based in
the North-East of England, which is now a world-recognized center for
automotive development, AVID Technology is a renowned leader in the design and
manufacture of electrified powertrain and advanced thermal management systems
for heavy-duty and high-performance electric and hybrid vehicles. Its technology
also improves conventional internal combustion engine efficiency through
parasitic loss reduction, efficient thermal management, lubrication,
electrified ancillary systems and waste heat recovery.
The
company develops powertrain improvement solutions for a wide range of electric
and hybrid vehicle applications, including high performance passenger cars,
heavy duty buses and trucks, as well as motorsport vehicles and off highway
machinery. Its high efficiency electric motor and power electronics technology
delivers class-leading electrified powertrains and propulsion systems.
In order
to test and characterize the high performance electric motors used in electric
and hybrid powertrains, AVID Technology designed and built a special purpose
test rig. Central to the design of the test rig is an innovative wireless
rotary torque measurement device from Sensor Technology. These non-contact
surface wave acoustic (SAW) transducers offer significant advantages compared
with strain gauges, magnetic torque sensors and optical devices that might be
fitted to a conventional dynamometer for motor characterization.
Sensor
Technology SAW-based devices are non-contact, robust and highly accurate.
TorqSense torque sensors use two tiny SAW devices made of ceramic piezoelectric
material containing frequency resonating combs. These are glued onto the drive
shaft at 90 degrees to one another. As the torque increases the combs expand or
contract proportionally to the torque being applied. In effect the combs act
similarly to strain gauges but measure changes in resonant frequency.
The adjacent RF pickup emits radio waves towards the SAWs, which are then reflected back. The change in frequency of the reflected waves identifies the current torque. This arrangement means there is no need to supply power to the SAWs, so the sensor is non-contact and wireless.
These
characteristics make the TorqSense transducers ideal for use in the stepper
drive test rig. AVID Technology sales director Jordan Taylor explains: “The
TorqSense transducer was chosen as it allowed us to use a fixed pedestal load
motor and eliminate frictional losses and parallax errors from the load
installation in the measurements. This allows AVID to produce very accurate
performance characterization results compared to a conventional motor
dynamometer.”
Not only
has the sensor delivered superior and more accurate characterization results,
it also enabled AVID to design a simpler test rig.
Reporting
that the device has performed flawlessly in the application to date, AVID
Technology is confident that its test rig will be key in enabling it to provide
even smarter powertrain electrification, delivering on its vision of a cleaner,
greener world.
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