5.3.5. Control loops configuration
5.3.5.1. Control mode configuration
The DM2020 manages up to three control loops depending on the operating mode of the drive: The torque, velocity and position loop,
each inside the other, with the torque loop innermost, the velocity loop intermediate and position loop outermost, so that the output of
each loop is the reference for the next internal loop.
The following figure illustrates the general block diagram of the control structure
Feedforward
FF
Position
+
+
Velocity
Microinterpolator
FSM
references
Position
controller
Feedback
(Position and Velocity)
Velocity
controller
Torque
controller
Depending on the structure chosen, the user will have to provide the reference torque, speed or position.
INFORMATION
The control loops must be calibrated by quali
�
ed personnel.
5.3.5.2. Torque loops parameters configuration
The torque loop (or current, given the direct proportionality) is the innermost. The parameters are set automatically from the motor
data, which in turn is set via the
Motor Parameters
menu.
The user can configure the bandwidth passing through the closed torque loop via the Terminal window, setting the “
bandPass
” variable;
the possible values are 3000 (default), 2000.1000, 600.400 in Hz.
The standard network corrector (PI) is recognised, characterised by two parameters. Subsequently, there is a sequence of
�
lters and one
�
lter on the feedback chain; this allows for the use of more complex control structures, as well as
�
ltering of
known disorders (notc
��
lter).
INFORMATION
Changing the bandwidth with regard to the default value may result in reduced motor performance.
5.3.5.3. Speed loops and filters parameters configuration
The speed control must ensure that the motor speed follows the speed reference as closely as possible, both in static and dynamic
conditions. The quality of response from the system depends on the loop parameter settings.
Basic velocity control is PI (proportional-integral) with an additional Feedforward (ff_calc) command, torque compensation and variable
saturation (SAT_VARIABLE).
The proportional term produces an action; this is stronger the bigger the error, while the integral term (velocity error) corrects small errors
that remain in time, due to constant disturbance and enables required targets to be reached.
The Feedforward block is used to minimise the velocity error in the case of disturbance known beforehand, directly contributing to the
velocity reference processed by the PI regulation, with the linear combination of velocity, acceleration, jerk and delayed velocity in n
samples references, calculated downstream the microinterpolator and makes it possible to minimise errors during transients.
The variable saturation block prevents the formation of fixed axis position instability (zero velocity reference, acting as a “low pass”
filter with an extremely limited band.
To set the parameters, select
Velocity loop
from the
Navigation area
: A window will open showing the block diagram of the loop in question.
The standard network corrector (PI) is recognised, characterised by two parameters. Subsequently, there is a sequence of filters and one
filter on the feedback chain; this allows for the use of more complex control structures, as well as filtering of known disorders (notch filter).
MAR2-E-191
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