Setpoint channel and closed-loop control
7.4 Vector speed/torque control with/without encoder
Drive converter cabinet units
278
Operating Instructions, 07/07, A5E00288214A
If vibrations occur with these settings, the speed controller gain (Kp) will need to be reduced
manually. Actual-speed-value smoothing can also be increased (standard procedure for
gearless or high-frequency torsion vibrations) and the controller calculation performed again
because this value is also used to calculate Kp and Tn.
The following relationships apply for optimization:
●
Increasing Kp will speed up the controller and reduce overshoot. However, signal ripples
and vibrations in the speed control loop will increase.
●
Although reducing Tn will also speed up the controller, it will increase overshoot.
When setting speed control manually, you are advised to define the dynamic response via
Kp (and actual-speed-value smoothing) first, so that the integral time can subsequently be
reduced as much as possible. Please remember that closed-loop control must also remain
stable in the field-weakening range.
To suppress any vibrations that occur in the speed controller, it is usually only necessary to
increase the smoothing time in p1452 for operation without an encoder or p1442 for
operation with an encoder, or reduce the controller gain.
The integral output of the speed controller can be monitored via r1482 and the limited
controller output via r1508 (torque setpoint).
Note
In comparison with speed control with an encoder, the dynamic response of drives without
an encoder is significantly reduced. The actual speed is derived by means of a model
calculation based on the converter output variables for current and voltage that have a
corresponding interference level. To this end, the actual speed must be adjusted by means
of filter algorithms in the software.
Function diagram
FP 6040
Speed controller
Parameters
•
r0062
CO: Speed setpoint after the filter
•
r0063
CO: Actual speed value smoothed
•
p0340
Automatic calculation, control parameters
•
r0345
CO: Rated motor startup time
•
p1442
Speed-actual-value smoothing time (VC)
•
p1452
Speed-actual-value smoothing time (encoderless VC)
•
p1460
Speed controller P gain with encoder
•
p1462
Speed controller integral time with encoder
•
p1470
Speed controller encoderless operation P gain
•
p1472
Speed controller encoderless operation integral time
•
r1482
CO: Torque output I speed controller
•
r1508
CO: Torque setpoint before supplementary torque
•
p1960
Speed controller optimization selection
