Configuration
5.2 Configuring procedure
1FT2 synchronous motors for SINAMICS S120
Configuration Manual, 03/2021, A5E50645584B AA
63
Free duty cycle
A free duty cycle defines the curve of the motor speed and the torque over time.
Figure 5-4 Example of free duty cycle
Procedure
Determine the required motor torque as follows:
1. Define a load torque for each time slice. Also take the average load moment of inertia and
motor moment of inertia into account for acceleration operations. If required, take a
frictional torque into account that opposes the direction of motion.
2. With mounted gearbox:
Determine the load torque and the acceleration torque that must be supplied by the motor.
Take the gear ratio and gear efficiency into account.
A higher gear ratio increases positioning accuracy in terms of encoder resolution. For any
given encoder resolution, as the gear
ratio increases, so does the resolution of the
machine position to be detected.
The following formulas can be used for duty cycles outside the field weakening range.
For the motor torque in a time slice Δt i the following applies:
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