Power density, efficiency, eco-nomy,
smooth operation and ro-bustness
are essential considera-tions
in the development of electric
drives. Until now, it has been dif-ficult
to measure smooth opera-tion
with its influence on lifetime
and driving comfort. To tackle this
challenge, at AVL we have develo-ped
a new, highly dynamic torque
sensor with a high bandwidth that
enables the measurement of dyna-mic
torque, like torque ripples and
lateral forces over the entire speed
range of the electric drive.
HANDLING TOXIC TORQUE
Toxic torque has a negative im-pact
on the quality of the elec-tric
drive. Among other things, it
causes unsteady driving behavior
due to torque ripples and cogging
torque, and acoustic emissions
(NVH). This ultimately leads to a
reduction in efficiency and lifetime.
Getting a better handle on these
physical phenomena is the focus
of a great deal of interest in electric
motor development and validation.
However, it is in this area that con-ventional
measurement technology
has reached its limits. While abso-lute
torque can be measured with
high accuracy using strain
gauge-based sensors, these
have their weaknesses in
the resolution of dy-namic
effects. This is
due, in part, to the
sensor technology
itself (DMS), which
detects the torque via
a defined twist. And
it is also because of
its integration in the
shaft train, which acts
as a kind of mecha-nical
low-pass fil-ter
due to its reso-nant
frequency (100
to 200 Hz). Compared to our in-novative
solution, these sensors are
very soft and slow in their dynamic
measurement resolution.
AVL Dynamic Torque Transducer
1 8 e-mobility
Illuminating
the E-Motor
PIEZOELECTRIC SENSOR
TECHNOLOGY
This is exactly where our Dynamic
Torque Transducer (DTT) comes
in. Instead of using strain gauges,
we employ piezoelectric sensor ele-ments
which offer enormous stiff-ness
and dynamics (>150 Nm/ms
and frequencies up to 25 kHz). Due
to the mounting location between
the electric motor and the mounting
bracket of the test rig, the DTT is at
the closest possible position to the
air gap torque. This means that it
doesn’t impose a limit on the speed,
and high-frequency torque ripples
are not absorbed by the soft shaft.
In addition, the installation of the
sensor does not influence or change
the mechanical setup. Torque ripp-les,
cogging torque, and stator-ro-tor
interactions on a certain rotor
angle can all be analyzed for motor
development, durability or end-of-line
tests. Additionally the sensor
is not limited to e-motor develop-ment
tasks, but also offers a great
deal of potential for many more
tasks where dynamics is required,
space is limited, and stiffness is an
essential factor.
Fast sensor technology of course
requires powerful measurement
equipment. This is why we re-commend
the AVL X-ion™, a mo-dular
data acquisition tool which
is fully compatible with the Dy-namic
Torque Transducer. X-ion
combines everything you need,
from the electrical power, to NVH
and dynamic torque measurement
tasks (multi physics), and more. All
raw signals are recorded in the ac-companying
IndiCom™ software
at a high resolution (up to 2 MS/s)
and synchronously in real-time.
Together with the AVL IndiCom
Dynamic Torque Toolbox, the full
potential of the sensor can be rea-lized.
Dynamic torque data can be
recorded with electrical values like
currents, voltage and NVH measu-rements.
All of these measurements
are contained within one dataset
and synchronized for convenient
and reliable data analysis.
AVL Dynamic Torque Analysis