l
Another criterion for a reliable knowledge of mass inertia is functioning
torque feed forward control (see Section "Pre-control" on page 140). Multiply
the currently configured value of
P 1516[0] - SCD_JSum
by
P 376 - CON_
IP_TFFScale
and set
P 376 - CON_IP_TFFScale
back to 100%.
l
Set
P 350[0] - SEL_ObserverMethod
= OBS1(1) and
P 354[0] - CON_
SCALC_ObsDesignAssi
= DR(2).
l
Start the control.
The setting parameter for the observer is the time constant P 353[0] - Tf. Use twice
the time constant of the previously used speed filter P 351[0] - CON_SCALC_Tf as
an initial value. Configuration is also a compromise between input signal smoothing
and phase shift in the control circuit. However, the observer does not have such a
great effect on phase shift in the speed control circuit as a filter.
7.4.1.2 Reduction of gain at low speeds.
With speed controllers set to be very dynamic, undesirable oscillation of the speed
controller may occur at low speeds or at zero speed. An appropriate setting of P 336
- CON_SCON_KpScaleSpeedZero reduces this tendency to oscillate.
Image 7.23: Reduction of gain at low speeds.
MOOG
ID No.: CB40859-001 Date: 11/2020
MSD Servo Drive - Device Help
134
7 Control
7.4.1.3 Quick stop without sensor
In the event of a wire break on the encoder system the drive is shut down in
sensorless mode on the preset quick-stop ramp (see Section "Error reactions" on
page 325 and Section "Stop ramps" on page 248). Due to the lack of dynamism at
low speeds, the sensorless control is very "imprecise". To enable the drive
nevertheless to be run down smoothly to speed 0, as from the speed threshold
parameterized in P 355[0] - LowSpeedLimit the controller switches to a
current/frequency (IF) control. For stabilization, an additional, cumulative d-current
must be injected that can be set via the P 355[1] - d-current Injection parameter. The
speed controller gain is reduced by the factor P 355[2] - SpeedControlGainScale.
Image 7.24: Quick stop without sensor