Siemens SINAMICS DCM Manual page 319

Commissioning
8.8 Manual optimization
8.8.1 Optimization of closed-loop armature current control
Determining the armature circuit parameters (3 options)
1. Determining the armature-circuit parameters according to the motor list
Take the armature circuit resistance (p50110) and armature circuit inductance
(p50111) from the motor manufacturers data.
Disadvantage: The data is very imprecise and/or the actual values deviate significant-
ly.
Feeder cable resistances are not taken in the armature-circuit resistance. Additional
smoothing reactors and feeder cable inductances are not taken into account in the
armature-circuit inductance.
2. Roughly estimating the armature-circuit parameters from the rated data for the motor
and line supply
The basis of this formula is that for the rated armature current, there is a drop of 10%
of the rated armature voltage across the armature circuit resistance Ra.
This formula is based on the empirical value: The transition point from discontinuous to
continuous current is approximately 30% of the rated motor armature current.
3. Determining the armature circuit parameters by measuring the current/voltage
• Establish closed-loop current controlled operation
• Calculate the armature circuit resistance p50110 from the armature current and
320
p50110 =
p50101 =
p50100 =
p50111 =
r50071 =
p50100 =
- p50084=2: Select closed-loop current controlled operation
- p50153=0: Precontrol disabled
- p50082=0: Switch-off the field to prevent motor from moving and, where nec-
essary, lock the rotor of the DC motor if retentiveness is too high.
- p50354=5 %: Threshold for overspeed protection
- Enter 0 for the main setpoint.
- If "OPERATION ENABLE" has been applied and the "SHUTDOWN" com-
mand is entered, an armature current of approximately 0% will now flow.
armature voltage
- Gradually increase the main setpoint (shown at r52011) until the actual arma-
ture current value (r50019 as a % of the unit's rated armature current) reaches
approximately 70% of the motor's rated armature current.
- Calculate the armature circuit resistance:
Ra[Ω] = r50038 / (r50019 × p50100) = armature voltage [V] / armature current
[A]
ac.maher.co.ir
Armature-circuit resistance [Ω]
Rated motor armature voltage [V]
Rated motor armature current [A]
Armature circuit inductance [mH]
Rated unit supply voltage, armature [V]
Rated motor armature current [A]
SINAMICS DCM DC Converter
Operating Instructions, 02.2015, A5E34763375/RS-AA/001