Adaptation Of The Armature And Field Current Controller - Siemens SINAMICS DCM Operating Instructions Manual

10.12

Adaptation of the armature and field current controller

The current controller (armature current controller and field current controller) of the
SINAMICS DCM operate with a controlled system that is very non-linear.
Types of non-linearity
There are 2 types of non-linearity:
1. Non-linearity of the gating unit:
In the armature circuit, there is a significant difference in the controlled system gain (= line-
commutated thyristor converter in the B6 bridge connection) between discontinuous and
continuous current.
In the field circuit, the system is essentially always in the discontinuous current range, but
the control characteristic of the B2Z or B2 bridge manifests a significant degree of non-
linearity.
2. Non-linearity of the load inductance (= armature circuit or field circuit of the motor):
At higher currents, both the armature winding as well as the field winding - or also when
there is a smoothing reactor available in the armature circuit, can go into the magnetic
saturation range; as a consequence, they can have a significantly lower inductance than at
low currents.
The inductance as a function of the current is modelled according to the following diagram:
SINAMICS DCM Control Module
Operating Instructions, 06.2010, C98130-A7067-A1-02-7619
10.12 Adaptation of the armature and field current controller
Descriptions of functions
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