Pid Current Controller Function Block; Figure 30 Pid Current Controller Function Block - WAGO 750 Product Manual

750-1632/000-100 Functions
Using the DG_RAMP_ON and DG_RAMP_OFF parameters, the ramps can be set as
percentages. Values can be specified in steps of 0.01 % of the nominal current.
Using ramps avoids the problem of overshooting during a hard switch-on of the dither sig-
nal, since an additional DC component is generated at this time. Furthermore, the startup
ramp provides a careful solution to overcome the static friction.
Dither Signal Form (DG_WAVEFORM Parameter)
The DG_WAVEFORM parameter can be used to specify whether the dither generator
generates a square-wave signal or a sinusoidal signal.
Dither – Automatic Amplitude Adjustment (DG_AUTO_AMPL_ADJ Parameter)
When this function is activated with the DG_AUTO_AMPL_ADJ parameter, the dither am-
plitude setting is automatically limited if the resulting signal from the target current and
dither exceeds the specified limitation of the valve adjustment. Thus the dither signal is
not unilaterally limited and remains symmetrical.
Dither – DC Correction (DG_DC_CORRECTION Parameter)
Automatic DC tracking is switched on/off with the DG_DC_CORRECTION parameter.
An applied dither signal can cause asymmetries in the coil current and a shift in the DC
component. As a result, deviations from the parameterized setpoint can occur. The dither
generator can filter out the dither signal applied to the DC signal and compensate for the
deviations by comparing the parameterized setpoint and the measured and filtered actual
current.

4.4.2.7 PID Current Controller Function Block

Figure 30: PID Current Controller Function Block
A fast PID current controller is responsible for precise control of the valve current. The
8 Pa-
control parameters are CC_KP, CC_KI and CC_KD. They can be set directly in
rameter Tables 168 and 169 [} 42].
The teach-in function allows the control parameters to be automatically determined by the
8 Current Controller Teach-in
I/O module; see section [} 66].
Product manual | Version: 1.1.0 51
Proportional Valve Module 2-3-4