QSH4218 Manual (V1.03 /13-November-2007)
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Copyright © 2007, TRINAMIC Motion Control GmbH & Co. KG
5 Considerations for Operation
The following chapters try to help you to correctly set the key operation parameters in order to get a
stable system.
5.1 Choosing the best fitting Motor for an Application
For an optimum solution it is important to fit the motor to the application and to choose the best
mode of operation. The key parameters are desired motor torque and velocity. While the motor
holding torque describes the torque at stand-still, and gives a good indication for comparing different
motors, it is not the key parameter for the best fitting motor. The required torque is a result of static
load on the motor, dynamic loads which occur during acceleration / deceleration and loads due to
friction. In most applications the load at maximum desired motor velocity is most critical, because of
the reduction of motor torque at higher velocity. While the required velocity generally is well known,
the required torque often is only roughly known. Generally, a longer motor and a motor with a larger
diameter delivers a higher torque. But, using the same driver voltage for the motor, the larger motor
earlier looses torque when increasing motor velocity. This means, that for a high torque at a high
motor velocity, the smaller motor might be the better fitting solution.
Please refer to the torque vs. velocity diagram to determine the best fitting motor, which delivers
enough torque at all desired velocities.
Hints:
Q: How to determine the maximum torque required by your application?
A:
Just try a motor which should roughly fit. Take into consideration worst case conditions, i.e.
minimum driver supply voltage and minimum driver current, maximum or minimum environment
temperature (whichever is worse) and maximum friction of mechanics. Now, consider that you want
to be on the safe side, and add some 10 percent safety margin to take into account for unknown
degradation of mechanics and motor.
