Determination Of The Flux Direction At Startup - BONFIGLIOLI ACTIVE CUBE Applications Manual

5.1.1.3

Determination of the flux direction at startup

If the frequency inverter were started in sensor-less operation, there would be an alignment process
of the PMSM at the impressed starting current, unless further measures are taken. Depending on iner-
tia and attenuation, decreasing torsional vibrations would result from such an alignment process. To
avoid this, the starting current is impressed in exactly the same direction as the flux when the fre-
quency inverter is turned off. The angle is saved permanently to ensure it is not lost when mains
power fails (Parameter
If it is not guaranteed that the machine has the same orientation during startup as during shutdown,
the flux direction must be identified upon startup (Parameter
"20-Only Fluxdirection identification"). The process will take approx. 35 ms.
If it is not guaranteed that the machine stands still upon startup,
must be set to "10 .... 15-Quick Synchronisation...". Here, it must be noted that only torsional fre-
quencies up to approx. 200 Hz can be identified reliably.
Due to the search run (
startup of the standing machine will be delayed additionally by approx. 150 ms.
Parameter
No. Identifier
645
Operation Mode Search Run
Operation Modes of Parameter 645
0 - off
10 - Quick Synchronisation
11 - Quick Synch. acc. to Preset Value
14 - Quick Sync., Clockwise Only
15 - Quick Sync., Anti-clockwise Only
20 - Only Fluxdirection identification
30 - Operation above Frequency Limit
11/13
Operation Mode Search Run
Operation Mode Search Run
ACU
Spindle Applications
645 to "0-Off").
Operation Mode Search Run
Operation Mode Search Run
645 to "10 .... 15-Quick Synchronisation..."),
Unit Setting range
A Selection
The synchronization to a rotating drive mechanism is
deactivated.
An attempt is made to synchronize to the drive in
positive direction (clockwise field of rotation) and in
negative direction (anticlockwise field of rotation).
The search direction is defined by the sign of the set
point. If a positive set point (clockwise field of rota-
tion) is entered, the search is in a positive direction
(clockwise field of rotation), with a negative set point,
the search is in a negative direction (anticlockwise
field of rotation).
Synchronization to the drive is only done in positive
direction (clockwise field of rotation).
Synchronization to the drive is only done in negative
direction (anticlockwise field of rotation).
Only the flux direction is identified for a synchronous
motor ( 30 = 806). The drive must be
Configuration
at a standstill. Synchronization to a turning drive is not
possible.
Search run is carried out for a synchronous motor
( 30 = 806). The search is continued
Configuration
until a torsional frequency is identified which is higher
than the
Frequency Limit
drops below the frequency limit, the search run is
continued. This Operation Mode can be used for oper-
ation of synchronous motor in torque-controlled
drives. Use in wind turbines is also possible.
645 to
Default settings
0 - off
624. If the stator frequency
645
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