Baumuller b maXX BM5800, Parameter Manual

Page: 713 / 816

Description of the Software Modules and Parameters
Parameter manual b maXX BM5800
Document No.: 5.16029.03
713
of 814
3
If the output value of the I
2
t-sub-model (PU-I
2
t-actual value) reaches 105% of
Z
175.8
–
the warning 206 is set and the total current is limited to the maximum PU continuous cur-
rent
Z
175.7
–
.
If the PU-I
2
t actual value reaches 95%, the current limit is canceled on the part of the I
2
t-
sub-model.
If a current limit is additionally activated by the power electronics sub-model, the warning
206 remains. The warning and the limit is disabled not before the current limit is canceled
from both sub-models.
Power electronics sub-model:
The temperature of power electronics is emulated and is standardized using the tempera-
ture threshold

Sem pu
(temperature actual value =

Sem pu
corresponds to 105% load),
which was defined in the characteristics of the device. Thus, the load value is compatible
to the I
2
t-sub-model.
If the value reaches 105%, warning 206 is set and the total current is limited to the max-
imum PU continuous current
Z
175.7
–
.
The power electronics sub-model cancels the current limit after

Sem pu
falls below the
value 105% within 30 s. The 30 s time slice is an empirical value, which is great enough
so that all devices can recover thermally.
However, the current limit still can be activated by I
2
t-sub-model.
Protective function PWM reduction
In order to avoid current limiting, the switching frequency can be automatically reduced
(i.e. PWM frequency
Z
130.15
–
is halved). Thereby, the switching losses in the IGBTs are
reduced.
If the temperature of the power electronics exceeds the temperature threshold

Sem LimRed
, the PWM frequency is halved and warning 216 is triggered. The tempera-
ture threshold

Sem LimRed
is lower than the threshold

Sem pu
, which triggers the cur-
rent limit.
The PWM reduction doesn't change the value of the PWM frequency
Z
130.15
–
, which
was set.
NOTE!
m
As long as the safety function current limit is active and the output frequency is
Z
47.49
–
< 15 Hz (current derating dependent of the output frequency is effec-
tive), the total current is limited to the smallest existing value of the maximum PU
continuous current
Z
175.7
–
and will remain on this value. This means, that during
this time
Z
175.7
–
and the active current limit can decrease, if the output frequency
drops. The active current limit however cannot get larger, if the output frequency
Z
175.7
–
increases. The active current limit remains on the smallest existing value.
m
At the protective function current limit the "Max. drive current available"
Z
19.5
–
is
reduced, whereat the settable limit of the total current "Max. drive current"
Z
19.6
–
isn't changed. The reduction of the total current takes place via the current torque,
i. e. via the "Max. available torque current"
Z
19.8
–
.