Baumuller b maXX BM2500, Operating Manual

Page: 112 / 822

Configuration
Parameter manual b maXX BM3000
Document no.: 5.12001.07 Baumüller Nürnberg GmbH
112
of 820
4.4
The maximum cross current I
sq max
is calculated from the "Max. drive current actual val-
ue"
Z
19.5
–
I
max act
and by reduction the field current. The "Max. drive current actual val-
ue"
Z
19.5
–
in general is the same as the maximum drive current
Z
19.6
–
. However, this
current and the actual maximum torque can be reduced by the power unit overload mon-
itoring (refer to "Bit mask of external drive current limit"
Z
138.6
–
).
Additionally, in the field weakening range the torque is limited by the maximum power.
Therefore, the maximum available torque
Z
138.20
–
is constant in the base speed range.
In the field weakening range it decreases inversely proportional to the speed (see
Z
Fig.
66
–
on page 112).
Symmetric torque limit
The symmetric torque limit M
limit
(
Z
138.22
–
) influences the set value of the cross current
controller, which controls the torque-generating current. The correspondent limit for the
torque-generating current I
sq limit M
must be fit as follows.
with
Flux
setl
Magnetic flux set value in %
Z
146.13
–
Kt Kt = Kt
corr
· Kt factor, in Nm/A
Kt
corr
Kt correction factor,
Z
138.23
–
Kt factor Motor Kt in Nm/A
Z
107.44
–
Torque limits / torque current limits
Figure 66: a) Asynchronous motor: Torque limit above
Z
138.22
– 
b) Asynchronous motor: Overlap of several limits
If there are several torque limits
Z
138.22
–
, that result from the torque current limits
Z
138.2
–
,
Z
138.3
–
,
Z
138.14
–
,
Z
138.15
–
or from the breakdown torque-current limit op-
erating simultaneously then the smallest limit is decisive (compare
Z
Fig. 66
–
(b)). Note:
I
sq limit M
M
limit
Kt
Flux
set
100
-----------------

---------------------------- =
n [min ]
N
107.7
N
-1
N
max mech
107.26
max
M
m
[Nm]
(138.20)
M
n [min ]
N
107.7
N
-1
N
max mech
107.26
max
M
m
[Nm]
(138.20) M
a) b)
5000_0235_rev02_int
Lim
= (Iq ) =
f
Lim
(138.22)
Lim
min
(138.2,138.3,138.14,138.15)
Lim
(138.22) M
| | | |
f
(138.18)
base speed
range
field weakening
base speed
range
field weakening
effective
limits
=
M
Lim bd