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B-6 Control System
MN1901
B.2.2 Speed controller
The speed controller, shown in Figure 59, is also a PID controller. Gains are set using the Mint
keywords
KVPROP
,
KVINT
and
KVDERIV
. The speed is compared with the measured speed
and the error is fed into the PID control calculation. The result forms the torque demand for
the torque controller. To improve the performance of the derivative term, an optional filter is
included. The time constant of this filter can be set using keyword
KVDERIVTCONST
.
By default the filter is turned off, with
KVDERIVTCONST
set to zero.
When the MintDrive
II
is set to positioning mode (
CONFIG
is
_cfSERVO
), the profiler
acceleration is fed forward by gain
KACCEL
to give a contribution to the final torque demand.
The speed control calculation is performed every 250
μ
s. As with the position controller, the
gain values
KVPROP
,
KVINT
,
KVDERIV
and
KACCEL
must be tuned for each application.
This can either be performed automatically within the Commissioning Wizard, or manually
using the Fine-tuning tool of Mint WorkBench.
KACCEL
KVPROP
KVINT
KVDERIV
dt
d
dt
Velocity
error
Proportional gain term
Integral gain term
Derivative gain term
Measured speed
(VEL)
Torque demand
Acceleration feedforward term
(CONFIG _cfSERVO only)
Profiler acceleration
Speed demand
+
+
+
+
+
+
-
(KVDERIVTCONST)
Filter
Figure 59 - Speed control system
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