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phytron
43 MA 2107-A005 EN
A4 Current Shaping CS
Current Shaping (CS) is a circuitry method for delivering a true phase current which
corresponds for a wide range of frequencies to a selected current shape (CS= 4 quadrant
current regulation).
If the stepper motor is driven without CS, the true current differs from the specified current,
even in the lower speed frequencies.
The 1/20 sine wave mode results in a current deviation as shown in fig. 23, for average
speed:
Fig. 24: Current Shaping CS
These typical deformations can be observed for all types of curves. They are caused by
the stepper motor inductance and the generator feedback which increases with the motor
speed.
The resulting ‚current queue’ makes precise current regulation possible Current Shaping
(CS= 4 quadrant current regulation), only. The amplitude of the ‚current queue’ varies
strongly during one revolution and may provoke a motor resonance effect which causes
step losses or desynchronization of the motor.
If the CS function is activated, the ‚current queue’ disappears and the resulting current is
close to the ideal shape.