DFSET, digital frequency, phase synchronisation, multi-axis synchronisation

Question:
Can the quality of phase synchronisation with master frequency coupling be improved by using multi-axis synchronisation with function block SYNC1?

Answer:
Yes. The master frequency pulses are read via the DFIN master frequency input, and the further master frequency processing is effected at specific points of time in 1 ms control cycle in the drive controller. For particularly high requirements to the phase synchronisation quality of master and slave of an electronic shaft (master frequency coupling) the relationship and synchronisation of the 1 ms control cycle starts must be considered. Due to the minimum frequency tolerances of the clocking quartz oscillators the start instants permanently change.

Estimation of the effects:
The effect on the individual controllers is not perceptible. The quality of the phase synchronisation in the master frequency interconnection, however, can be affected noticeably.
For constant master frequency the dynamic angular displacements will be less, and in case of significant modifications of the master frequency (acceleration/deceleration) they will increase. The effect is the most noticeable when operation is clocking (start-stop). Reason: A determined ramp is processed by the drives in correspondence to the different start instants.

Remedy:
Thanks to the activated multi-axis synchronisation (SYNC1) using CAN sync message the 1 ms control cycles of the controllers always have a determined relationship to each other (fix time relationship to each other).  Consequently, oscillations of the master frequency as well as ramps are processed simultaneously, which leads to an optimum phase synchronisation.

Together with the speed-dependent phase trimming under C0253 (see article 20037270) the optimum phase synchronisation between drives is achieved.

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