Baumuller b maXX BM5800 - A) Asynchronous Motor: Torque Limit above B) Asynchronous Motor: Overlap of Several Limits

Configuration
Parameter manual b maXX BM5800
Document No.: 5.16029.03 Baumüller Nürnberg GmbH
82
of 814
3.4
Additionally, in the field weakening range the torque is limited by the maximum power.
Therefore, the maximum available torque
Z138.20– is constant in the base speed range.
In the field weakening range it decreases inversely proportional to the speed (see ZFig.
33– on page 82).
Symmetric torque limit
The symmetric torque limit M
limit
(Z138.22–) influences the set value of the torque current
controller, which controls the torque-generating current. The correspondent limit for the
torque-generating current I
sq limit M
will be fit as follows.
with
Flux
setl
Magnetic flux set value in % Z146.13–
Kt
upd
Kt updated Z155.24–, in Nm/A
Torque limits / torque current limits
Figure 33: a) Asynchronous motor: Torque limit above Z138.22– 
b) Asynchronous motor: Overlap of several limits
If there are several torque limits Z138.22–, that result from the torque current limits
Z138.2–, Z138.3–, Z138.14–, Z138.15– or from the breakdown torque-current limit op-
erating simultaneously then the smallest limit is decisive (compare ZFig. 33– (b)). Note:
In ZFig. 33– (b) the "Current mode" is assumed (Z138.1– bit 3 = 1) with regard to the
parameters Z138.2–, Z138.3–, Z138.14–, Z138.15–.
Particular case synchronous motor with interior permanent magnet (IPMSM)
The torque is calculated from the characteristic map of the IPMSM and from the currents
according to the following formula:
I
sq limit M
M
limit
Kt
upd
Flux
set
[%]
--------------------------------------------=
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