Controllers
Parameter manual
b maXX
BM5800
Document No.: 5.16029.03
Baumüller Nürnberg GmbH
490
3.7
example). The controller is not provided enough voltage if
is higher than
. The current cannot be compensated. Furthermore, a wind-up effect occurs in
the current controller (the I-component of the controller steadily increases without the cor-
recting variables increasing). Amongst others this is due to the coupling between d- and
q-current components. If the current deviation is lower an unintentional delay of the cor-
recting variables occurs. This can cause a strong overshoot.
Roughly the voltage at the motor is determined by two variables. On the one side is the
speed via the Back-EMF voltage (in the q-component of the motor voltage), on the other
side the torque via the torque current and the available impedance L
q
*
e
(L
*
e
at the
ASM) in the d-component of the motor voltage.
1
If the value of the Usd voltage
is below the (1/
2)-fold of the available phase
voltage U
ph,Max
it should be checked if the field weakening controller applies the re-
quired field weakening current (and at the ASM - if the magnetic flux weakening is suf-
ficient). If the latter is not the case it could be that the field weakening controller does
not apply the field weakening current quickly enough. However, the field weakening
controller can be adjusted more dynamically or the controller can be supported by the
use of the field weakening characteristic. Another cause of an insufficient field weak-
ening is that the field current reached its limit (field current specification at the SM
). In general, the field current specification value can be set at half the motor-
nominal current (if higher values are required contact the motor manufacturer).
2
If the value of the Usd voltage
is above the (1/
2)-fold U
ph,Max
it is recom-
mended to activate the breakdown torque limit (
bit 2 to 1) by the default set-
ting of the breakdown torque factor
. If the Usd voltage is not limited to the
assumed value U
d,Max
it is recommended to activate the adaption for the breakdown
torque limit (
bit 5 to 1). If the Usd voltage is limited and the issue with the con-
trolled current remains then the field weakening should be controlled as described in
point 1 otherwise carry on with point 3.
3
If the d-,q-currents are now properly controlled the breakdown torque factor at the SM
can be gradually increased to achieve more torque current. However, this leads to a
higher field current amplitude (lower power factor). Thereby, should be checked if the
field weakening controller is operating sufficiently and if the field current amplitude is
adequate (refer to point 1).
Breakdown torque controller (feedback controller)
At the controlled processing the maximum torque current is limited by a PI controller and
provides the maximum possible torque current to the available voltage. Because the max-
imum torque current is adjusted this process is independent to the set motor parameters.
The breakdown torque controller is activated at bit 4 of parameter
and at the
same time deactivates the breakdown torque parameters. The input values are the same
as at the field weakening controller except that there is an own factor (
) for the
breakdown torque control there is an own factor. As soon as the required voltage increas-
es the set voltage the torque current is limited by the PI controller and the controller is
immediately initialized to the present torque current. It is recommended to parameterize
this factor higher than the field weakening limit factor (
), so that the field weak-
ening controller always starts at first. The higher the present field current the lower the
present Uq voltage and due to this a higher torque can is available and a higher torque
can be reached.
