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8.1.8.3 D-component
Table 18: D-component
Parameter
P-0-2969
P-0-2970
P-0-2971
P-0-2978
The D-component scales the change of the actual value signal and ensures
a damped transient response of the pressure or swivel angle controller.
Differentiation results in a very high sensitivity, which responds also to
undesirable signals such as interference and can make the system unstable. In
the case of a constant actual value, the D-component does not respond, since the
change rate is zero.
The higher the D-component, the slower is the system's response. However, values
that are too small cause instability due to the gain of disturbances in the actual
pressure value signal.
8.1.8.4 Set the pressure controller PD-gain
The PD-gain corresponds to the summation of the P-gain and D-components
mentioned before, as described in chapter 5.3.1 "Structure of the control" on page
21.
The values of the PD parameters to be set (P-0-2963, P-0-2964, P-0-2969, P-0-
2970) vary depending on the application at hand. In general, it is valid that higher
values lead to a faster responding control. However, an excessive increase leads
to unstable characteristics, since the actual value that is fed back is continuously
increasing or decreasing (oscillation). The optimum value of the entire control gain
is a compromise between balancing characteristics and stability.
Notes on the setting of the individual parameters are given in the following:
Example 1
Fig. 29: Damped oscillation
Table 19: Setting of damped oscillation
Step
1
2
Commissioning | SYDFED-2X, SYDFED-3X, SYHDFED-1X
Designation
Pressure controller time constant D-component positive
Pressure controller time constant D-component negative
Pressure controller time constant swivel angle feedback
Swivel angle controller time constant D-component
command value
Damped oscillation
Time
Behavior/result
Overshoots (damped oscillation)
Actual pressure value still overshooting
Pressure
Action
Increase D-component
Reduce P-gain
RE 30017-B, Edition 11.2021, Bosch Rexroth AG
67/96
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