Lenze i950 Series, Manual

Page: 275 / 500

13.7.1 Correction of the stator leakage inductance (Lss)...
...and the current controller parameters by means of the saturation characteristic
For the most part, the electrical characteristics of the motor are the relevant factors for an
optimal current controller setting (Vp, Ti), especially the stator resistance and the stator leak-
age inductance (Lss). However, modern motors have their stator leakage inductance changed
along with the current level so that it is impossible to have an optimal current controller set-
ting for all working points at all times.
For applications with operating phases that involve very different current and torque require-
ments and, at the same time, high requirements on dynamic drive behaviour, the i700 servo
inverter provides the possibility of the correction of the stator leakage inductance and the cur-
rent controller settings by means of the adjustable saturation characteristic.
The saturation characteristic is a typical characteristic of motors of one type/size. It does not
depend on the maximum process current of the motor in the prevailing application. Thus the
defined values should be based on the key data of the motors. These are rated motor current,
peak motor current for a limited time and the ultimate motor current.
NOTICE
Impact of the saturation characteristic on the current controller feedforward control
▶
The saturation characteristic is not only used to correct the current controller, but it also
influences the current controller feedforward control (can be activated via parameter
0x2941 ).
The following picture shows a typical saturation characteristic of an MCS motor:
0 % 10 % 20 % 30 % 40 % 50 % 60 % 70 % 80 % 90 % 100 %
0 %
20 %
40 %
60 %
80 %
100 %
120 %
I/I
max
L/L
n
The saturation characteristic represents the change in inductance (L/Ln) as a function of the
motor current (I/Imax). The variables of both axes which were scaled to a reference value are
represented as percentages.
•
When a Lenze motor is selected, the saturation characteristic is already filled with values
typical of the series.
Configuring the motor control
Fine adjustment of the motor model
Correction of the stator leakage inductance (Lss)...
275