Lenze EDS4900U-REG - Manual (Page 107)

Configuration
7-16 48XX/49XXSHB0399
Rating to detect I
Fmin
With the parameter I
Fmin
(C231), the speed setting range is limited so that operation
at impermissible speed is avoided.
The following diagram is based on the standard excitation characteristic. The value
really required for I
Fmin
(C231) is however dependent on the excitation
characteristic of the machine used. The following indications can therefore only
serve the orientation.
4900Str032
1 , 0
0 , 5
1 2 % 1 9 % 3 2 % 3 9 % 4 7 % 5 7 % 7 1 % 1 0 0 %
I F
F r I
n r
m a x n
FIG 7-5 Detection of the min. field current in relation to the speed ratio
Example: n
rated
= 1500 rpm, n
max
= 3000 rpm, i.e. n
rated
/ n
max
= 0.5
The value to be set under C231 is to be calculated.
Result: For this speed ratio, the diagram indicates approx.
32% for C231.
If necessary, adapt the gain and the integral action time of the field controller under
C077, C078 to different field time constants of the motors. Set C077 and C078
that the field current does not oscillate in field weakening operation.
( V
ab
limitation
The integrated field controller enables the speed adjustment by field current
weakening. The field current operation is automatically derived from the control
level of the armature current controller. With the armature voltage limitation, the
max. motor voltage is limited to static V
Amax
= 1.05
ô V
Arated
(C090) (short-term
overswinging of the armature voltage possible).
Show/Hide Bookmarks