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Figure 1: Electric Motors for Improved Fuel Efficiency
efficiency. In applications where
more dynamic control is needed,
the use of PMSM makes more
sense. Then in some applications,
where the cost is critical and factors
such as weight-to-torque ratio and
robustness are needed, the use
of SRMs has been seen. Another
classic industrial ACIM application
is large HP (>15 HP) compressors.
Here SyncRM motors have started to
appear, as they have a very similar
structure to ACIMs, including the
same stator design with a different
rotor. However, for the same frame
size, you can increase the torque
and efficiency, or reduce the frame
size.
Then there are the applications
where there haven’t been any
motors, such as under the hood of
a car. Here, the electrical motor is
being used to replace the mechanical
serpentine belt, increasing efficiency,
as the load can come and go with
motors, while with the belt it is
always there even though it isn’t
needed. These days, everything
counts when it comes to efficiency
and fuel economy. Here the trend
has been to move from belt to BLDC
motor to PMSM. Another application
in cars that is utilizing electric motors
is drive by wire. Here, for example,
SRMs are being used to drive the
hydraulic pumps in the brakes. The
high-speed capability of the SRM can
build up pressure quickly, to allow
for fast break response.
Another very different application
space where the use of electrically
commutated motors has had a big
impact is battery-operated tools and
appliances. With the improvements
in battery technologies, such as
lithium-ion, we can now have vacuum
cleaners and power tools utilizing the
efficiency of BLDC motors. Initially,
these applications primarily used
brushed DC motors, but there was
a limitation on speed and torque.
The higher power/torque density of
BLDC motors allows for reasonable
weight, longevity and performance
that is close to matching the wired
version.
In home appliances, such as
washing machines, refrigerators,
dishwashers, air conditioners, etc.,
the primary workhorse, just as in
the industrial space, has been the
Figure 2b: SRM Drive Circuit
Figure 2a: Synchronous motor drive circuit
New-Tech Magazine Europe l 37