Bosch Rexroth PSI 6 Serie Betriebsanleitung Seite 390

390 / 460 Bosch Rexroth AG PSI 6xxx | 1070080028 / 08
Commissioning
Description of the controller:
The welding current controller in the PSI 6xxx is designed as a PI con­
troller.
The current deviation between the setpoint current and the actual cur­
rent is amplified in the PI controller via the P-factor and the I-factor to the
power unit of the timer. The P-factor in the controller is mainly responsi­
ble for the ratio of control deviation to regulation variable. In order to
achieve a steeper current increase, larger regulation variables are
required. To apply the mainly inductive gun with welding current, so a
larger P-factor is necessary. For small control deviations, the I
component is relevant in order to avoid current oscillation.
For secondary welding cables that are more highly inductive (e.g., large
weld window seam applications) or have higher ohmic secondary wel­
ding cables (e.g., fine point applications with small currents with tungs­
ten electrodes or brass electrodes), the control parameters can be
adjusted for faster current rise.
Current gain adjustment with the factor -10 to +10:
For a faster current increase, can be set first to +5 then to +8 and +10,
until oscillation or critical operation occurs. Afterwards the setting for
safe operation has to be reduced by 2 and this setting must be checked
in the desired current range.
To reduce the current increase, the settings -5, -8 and -10 are to be
selected adequately as above.
Rule parameter setting by P and I share:
If the setting variant over -10 to +10 is not sufficient, the P-factor and the
I-factor can also be set individually. When setting the parameters, the
P-factor should be increased first for a faster current increase.
The P-factor can be increased until the fastest welding current rise is
reached. (If the current increase no longer increases, the P-factor must
not be increased). Furthermore, the current increase form of an e-sha­
ped curve up to a max. 10% overshoot can be set.
To adjust the constant height of the current block, the I-factor can be
changed until the system starts to oscillate. Even after increasing the
P-factor too much, current oscillations can occur. After reaching a oscil­
lation, the P and I factor must be changed by 10 to 20% for safe opera­
tion. Current oscillations can be generated by too high a P-factor and a
low I-factor. The I-factor must be adjusted to the P-factor.
After finding suitable parameters, the operation between the minimum
and maximum welding current with the set parameterization must be
checked in approx. 6 current steps.
A higher transformer output voltage acts as a gain for the controller link
and requires a lower P-factor.
When operating in secondary current regulation, a lower P-share may
be required than in the primary current regulation.
Default values ​ ​ o f the control parameters:
P-factor 5.000 to 8.000 recommended setting range 800 to 50.000
I-factor 8 to 14, recommended setting range 2 to 80.
Depending on the surface, the control parameters can also be set in %
values. Then the 0% value corresponds to the default value of the
selected transformer.