Operation With Field Weakening - BONFIGLIOLI ACTIVE CUBE Applications Manual

•
5.1.1.4

Operation with field weakening

The amount of the induced voltage and thus the stator voltage to be applied by the frequency inverter
will increase in PMSM with the torsional frequency. The maximum torsional frequency of the PMSM is
limited initially by the maximum output voltage of the frequency inverter.
The torsional frequency of the PMSM can be increased further if the effective field is weakened by
superposition (field weakening). To that end, the modulation controller impresses a negative Isd cur-
rent in the machine, once the frequency inverter reaches the modulation limit.
If the speed is increased beyond the rated speed as the result of field weakening, the
open-circuit voltage of the machine will also increase with the speed.
NOTE
When the frequency inverter is stopped in the field weakening process, the frequency inverter or
other connected parts may be damaged, when no further measures are taken.
• For operation of a PMSM in the field weakening range, a sufficiently dimensioned brake chopper
must be connected to the frequency inverter, also refer to Chapter 5.1.3 "Brake chopper moni-
toring".
To activate operation in the field weakening range, Parameter
suitable negative value. This value depends on the characteristics of the machine and the desired field
weakening factor. The negative
NOTE
If the value is set too high, the magnets might be demagnetized and the machine might be dam-
aged.
Parameter
No. Identifier
744
Ref. Isd lower limit
5.1.2 Operation with encoder
In the speed sensor mode can be evaluated different systems.
Encoder system
Resolver
Incremental encoder
SinCos encoder
Reference pulse encoder
30
371 of the machine would be a practicable setting.
Rated Current
Unit
A
Evaluation unit
EM-RESxx
EM-ENCxx
EM-ABS-01
Digital input S6IND
ACU
Spindle Applications
Ref. Isd Lower Limit
Setting range
-o·I .. o·I
FIN FIN
Assigned speed sensor
744 is set to a
Default settings
0.0
2
2
2
1
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