Siemens SINAMICS DCM Manual page 320

• Calculate the armature circuit inductance p50111 from the armature current at the
Overall optimization of the armature circuit
• Checking the precontrol characteristic
Procedure
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• Checking the step response
Procedure
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SINAMICS DCM DC Converter
Operating Instructions, 02.2015, A5E34763375/RS-AA/001
transition point from discontinuous to continuous current
- Make an oscilloscope trace of the armature current.
- Starting from 0, gradually increase the main setpoint (shown at r52011) until
the armature current reaches the transition point from discontinuous to contin-
uous current.
- Calculate the armature circuit inductance using the following formula:
La[mH] = 0.4 × r50015 / (r50019 × p50100)
= armature voltage [V] / armature current at the transition point from discon-
tinuous to continuous current [A]
Set the function generator to a triangular waveform (0 % to 100 %), period =
10000 ms
Supply point: p50601[4] (see function diagram 6855)
Set p50082 = 0 (field off)
p50153 = 3 (influence of EMF disabled)
Record signals r52121 (output, precontrol) and r52110 (output, armature current
controller)
The parameters of the precontrol (Ra [p50110], La [p50111] and λa [p51591]) are
correctly set if the armature current controller output has the lowest possible value
(e.g. less than 5 %) over the complete setpoint range.
Set the function generator to a squarewave, with
step height = e.g. 5 %
offset = various values, e.g. 80 %
period = 1000 ms
pulse width = 500 ms
Supply point: p50601[4] (see function diagram 6855)
Set p50082 = 0 (field off)
Record signals r52118 (Ia-set) and r52117 (Ia-act)
Change controller parameters Kp (p50155) and Tn (p50156) until the step re-
sponse provides a satisfactory result.
In order to eliminate the influence of non-linearity of the armature circuit induct-
ance and gating unit, the armature current controller adaptation can be activated
(see function chart 6855).
ac.maher.co.ir
Commissioning
8.8 Manual optimization
321