Moog SmartMotor, Руководство разработчика

Страница: 891 / 909

A
ppend
ix
Moog Animatics SmartMotor™ Developer's Guide, Rev. L
Page 891 of 909
2. The load is very close to the operating limit. The motor will run quite warm as compared
to Point 1.
3. The load exceeds the advertised level and e10% expected range of possible
torque capabilities. In this case, the motor will most likely either overheat quickly and
fault out or immediately generate a position error because it simply does not have
enough power to support the load demand.
WARNING: Using an undersized motor can cause unpredictable machine
performance and is a potential safety hazard (see Motor Sizing on page 31).
4. The load exceeds the advertised operating limit of the motor. However, due to data
scatter and derating, there may be some motors that will work and others that do not.
This is because it falls within the range of ±10% variation for motors for a given size.
This can result in major problems for the machine builder.
For example, imagine designing a machine that operates in this range. Then you
replicate that machine with many of them running on a production floor. One day, a
motor at the lower end of the ±10% expected variation is placed on a new machine and
that motor generates spurious drive faults. It appears as though the motor is
malfunctioning because "all the other motors work just fine." This is unfortunate
because, in reality, all motors were undersized in the machine design and are now
operating outside of their advertised limits.
That is why it is important to properly calculate load torque to ensure the correct motor is
designed into the application (refer to the next section). Never assume that testing of one
motor means all motors of that size will work — it is simply not the case. You should never
proceed without performing proper load calculation and motor sizing. The goal is to have all
motors operating below the advertised limits, which will ensure reliable operation and long
motor life.
Proper Sizing and Loading of the SmartMotor
It is important to properly calculate load torque to ensure the correct SmartMotor is selected
and designed into the application. Consider the following sample figure. If properly
sized/loaded, the motor can run at or under the Continuous Torque limit continuously,
assuming 25°C ambient temperature. Further, the motor can tolerate intermittent operation
above the Continuous Torque limit up to the Peak Torque limit for brief periods. However, that
additional capacity may reduce as a function of time when operating above the Continuous
Torque limit.
In order to protect the motor, Moog Animatics has designed in safeguards to limit current that
may engage when the motor is operated for a sustained or accumulated brief periods above
the continuous ratings (i.e., operating above capacity for torque/time). This could lead to
position error or position error faults.
NOTE: These safeguards DO NOT indicate a defective motor. Rather, they are an
indication that the motor may not be properly sized for the intended application, or
that other design or environmental factors are affecting motor performance, such
as unintended axial or radial forces acting on the load, elevated ambient air
temperature, improper mounting that prevents adequate heat sinking, etc.
Appendix: Proper Sizing and Loading of the SmartMotor