Lenze 8400 - Manual (Page 238)

5 Motor control (MCTRL)
5.9 Servo control (SC)
238
Lenze · 8400 protec HighLine · Reference manual · DMS 3.0 EN · 03/2013 · TD05
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5.9.4.7 Optimising the behaviour in the field weakening range
The behaviour in the field weakening range is influenced by:
• the field controller
• the field weakening controller
• the field feedforward control unit
• adaptive adaptation of the P component of the field and speed controllers
• An additional limitation of the I component of the controller when the voltage limit is reached
Field controller
The field controller is designed as a PI controller.
The gain Vp ( C00077 ) of the field controller can be calculated using the motor rotor time constant
and the equivalent time constant of the current-controlled motor:
If the rated data of the motor and the mass inertia of the drive system are known, we recommend
the following setting:
[5-23] Recommendation for the setting of the gain and the time constant of the field controller

Tip!
The motor rotor time constant depends on the motor rotor resistance, the magnetising
inductance, and the leakage inductance.
• For an optimal calculation, we recommend to select the motor from the motor catalogue
of the »Engineer« first if a Lenze motor is used.  Selecting a motor from the motor
catalogue in the »Engineer« ( 132)
• If a third party manufacturer's motor is used, motor parameter identification must be
carried out previously.  Automatic motor data identification ( 134)

Note!
In general, these settings are pre-optimised so that further optimisation is not required.
Optimisation for special motors (e.g. mid-frequency motors) or for motors whose power
is not adapted can be carried out according to the algorithms shown in the following
sections.
Parameter Info Lenze setting
Value Unit
C00077 SC: Vp field controller 12.80
C00078 SC: Tn field controller 256.0 ms
V
PField
: Gain of the field controller ( C00077 )
T
R
: Motor rotor time constant ( C00083 )
T
Equivalent
: Motor equivalent time constant (approx. 2.5 ms)
a: Measure for damping (z. B. a = 2)
V
PField
: Gain of the field controller ( C00077 )
T
R
: Motor rotor time constant ( C00083 )
T
Equi
: Motor equivalent time constant
T
NField
: Time constant of the field controller ( C00078 )
V
PFeld
T
R
s [ ]
a
2
T
Replacement
ms [ ] ⋅
------------------------------------------------------ % [ ] =
V
PFeld
T
R
s [ ]
4 T
Replacement
ms [ ] ⋅
---------------------------------------------------
T
R
s [ ]
0.01 s [ ]
------------------- = ≈
T
NFeld
ms [ ] T
R
ms [ ] =