Description Of Functions - Siemens Sinamics S120 Function Manual

Function modules
7.9 Master/slave for Active Infeed
Communication using an analog setpoint
The analog setpoint between the CUs with Terminal Module 31 (TM31) can also be used as
an alternative to bus communication. The factory setting for the sampling time of analog
inputs and/or outputs is 4 ms (TM31 inputs/outputs sampling time p4099[1/2]). The sampling
times must be an integer multiple of the basic sampling times (r0110). The lowest common
denominator of the current controller clock cycle for the integrated infeeds must be selected
to implement the "master/slave" function. The sampling time of the analog inputs/outputs
should be the set to the same value as the current controller cycle (e.g. 250 µs). The slave
can then use the analog setpoint every second current controller cycle. with the dead time
corresponding to one clock cycle.
The advantages of this variant is that the communication system can be configured to be
independent of bus and master.
Disadvantages are the additional hardware wiring and the necessity to use one TM31 per
CU. This communication method is also more susceptible to EMC-related problems. It is not
absolutely essential to use a higher-level control (e.g. SIMATIC S7) for this system. Control
functions can also be implemented using DCC charts in individual CUs.
7.9.4

Description of functions

The "Mmaster/slave" function module is not implemented in the higher-level control, but
directly in the firmware of the CUs and infeeds. It is signaled by r0108.19 = 1 (option
"Master/slave" for infeeds selected in STARTER).
The V
Module control are implemented in the function module.
All infeeds must be parameterized in such a way that they are fully functional as both a
master and slave. The infeeds can be switched between master and slave role during
operation. Switchover is handled by a higher-level control according to the setting in
parameter p3513. A master is configured to operate with V
control, while the slaves operate only with current control (p3513 = 1). The setpoint input of
the active current I
links between the Control Units.
If the Active Line Module is used for reactive power compensation with external reactive
current setpoint, then the reactive current setpoint must also be wired for the slave. The
master-to-slave setpoint specifies only the active current.
When Active Line Modules have been deactivated, make sure that the maximum DC link
capacitance C
procedure (danger of overloading the pre-charging resistors).
Parameter p3422 (C
closed-loop control can be directly adjusted via this parameter when the master/slave
configuration changes, instead of changing the proportional gain of the V
(p3560). When parameter p3422 changes, parameter p3560 is recomputed automatically by
the firmware.
394
closed-loop control band and current setpoint via multiplexers of the Active Line
dc
is transferred from the master to the slaves via the communication
active(set)
for the remaining Active Line Modules is not exceeded during the switch-on
ZK
capacitance) can be changed in operation. This means that the
DC link
control (p3513 = 0) and current
dc
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
controller
DC link
Drive functions