Siemens SINAMICS Series Operating Instructions Manual page 347

Overall optimization of the armature circuit
• Checking the precontrol characteristic
• Checking the step response
SINAMICS DCM DC Converter
Operating Instructions, 12/2018, A5E34763375A
• Calculate the armature circuit resistance p50110 from the armature current and
armature voltage
- Gradually increase the main setpoint (shown at r52011) until the actual armature
current value (r50019 as a % of the unit's rated armature current) reaches approx-
imately 70% of the motor's rated armature current.
- Calculate the armature circuit resistance:
Ra[Ω] = r50038 / (r50019 × p50100) = armature voltage [V] / armature current [A]
• Calculate the armature circuit inductance p50111 from the armature current at the
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 continuous
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 discontinuous
to continuous current [A]
Procedure
- 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.
Procedure
- 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 inductance
and gating unit, the armature current controller adaptation can be activated (see
function chart 6855).
Commissioning
8.9 Manual optimization
345