Starting up
7-21
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0
7.3.4 Optimization of dynamic response
Overview
The motor axis driven by the FM 353 is driven by pure, direct control. It features
the following structure:
Stepper mo-
tor control
Current-sourcing
pattern counter
Current
regulator
DriveFM 353
Set
position
I
ph
− phase current setpoints of the n stator windings
Motor and
Machine
M
Phase current control
I
ph
Target
speed
PULSE
Direction
PWM/
BOOST
Fig. 7-10 Structure of the stepper motor axis
The dynamic response of the axis is determined by the design characteristics of
the machinery, such as friction, backlash, torsion, and the like. Being an open-loop
control module, the FM 353 must be subordinated to these factors as they bear on
parameterization. Following completion of basic startup as described in Section
7.3.3, optimization of parameterization should now be carried out geared to these
factors as well as to the technology.
Different requirements are imposed on the axis dynamic response for different
technological applications. Criteria for evaluating the quality of the positioning pro-
cedure may include the following:
Assessment criteria for the quality of the positioning process can include:
S Constant acceleration curve (soft travel behavior)
S Good uniformity of the traversing movement
(mechanical vibrations, stepper motor resonance!)
S Short positioning time
In most applications, several of these criteria will be important, so that most of the
time parameter selection is possible only with some compromise involved.
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