Closed-loop thyristor current control
5-12
System- and communication configuring D7-SYS - SIMADYN D
Edition 06.2002
FB–PA6 operates with the pre-set frequency PA6.FNT until the line
supply is connected to the Sitor set.
The pre-synchronization, which starts when the line supply is detected,
over NEP periods, harmonizes the interrupt frequency to the continuously
measured line supply frequency (XFN).
If the deviation is <10% of the line supply periods for PA6.NEP times
consecutively, the firing angle actual value (PA6.XAS) is enabled for the
closed-loop control (FB-PC6) (PA6.RDY).
The signal is output as a function of PA6.NEP, but at the earliest after two
line supply periods.
The current conduction duration PA6.YIT in the discontinuous range is
determined from the zero current signal from the Sitor.
Value 1 designates the limit of the non-discontinuous range.
5.2.1.3 Synchronization and pulse generation
The firing pulses for the thyristors for the specified firing angle are
generated by the firing angle controller FB–PC6.
The firing angle to be set is available at the firing angle controller input
PC6.WAS (= CPI.Y, output of the current controller) in the ASG format
and at the control input PA6.AQL in degrees.
The gating unit synchronizes the phase position of the pulses to the line
supply once every line supply period. Differences which occur are
corrected in the following periods.
Connections PA6.NCM, .FAM are especially used when the drive is
operated from weak line supplies.
FAM should be set to 0 for operation from “stable” line supplies.
The switch-over logic changes-over from closed-loop controlled operation
to open-loop control SOL.ISE. and also selects a torque direction.
Frequency
adaptation
Current conduction
duration