Parameter and variable descriptions 6-15 – Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE User Manual
Page 71
PARAMETER AND VARIABLE DESCRIPTIONS
6-15
1557-UM050F-EN-P – June 2013
7 Flux Control Parameters
Flux Regulator Bandwidth [Flxreg bandwidth]
Linear number:
97
Minimum value:
1 r/s
Maximum value:
30 r/s
Default value:
10 r/s
This parameter specifies the small signal bandwidth of the flux control loop. It is used in the calculation of the
flux regulator gain. The maximum bandwidth possible for stable flux control tends to decrease as motor size
increases.
Base Speed [Base speed]
Linear number:
98
Minimum value:
30.0 Hz
Maximum value:
100.0 Hz
Default value:
60.0 Hz
This parameter specifies the frequency at which field weakening begins. Base Speed is normally set equal to
the rated frequency of the motor. It can be set to a lower value only if the motor is specially designed to
operate at a higher than normal flux level without saturating.
Flux Command Base Speed [Flx cmd base spd]
Linear number:
100
Minimum value:
0.300 pu
Maximum value:
1.500 pu
Default value:
0.900 pu
This parameter specifies the value of the flux command at base speed and rated load. The flux command will
never be greater than this parameter, which can be set manually or by autotuning.
Flux Reference Step [Flx ref step]
Linear number:
102
Minimum value:
0.000 pu
Maximum value:
0.100 pu
Default value:
0.000 pu
This parameter specifies the magnitude of the step that is added to the flux reference to demonstrate the step
response of the flux loop. It is not saved and is initialized to zero at power-up.
Flux Command No Load [Flx Cmd no load]
Linear number:
103
Minimum value:
0.300 pu.
Maximum value:
1.500 pu
Default value:
0.700 pu
This parameter specifies the value of the flux command at no load. The flux command will change linearly from
Flux Command No Load to Flux Command Base Speed as Torque Reference changes from 0.00 to 1.00.
Reducing the motor flux improves efficiency when running for extended periods at less than full load. The
maximum torque capability of the drive is reduced in proportion to the reduction in flux. If the load increases
suddenly when the drive is running with reduced flux, there may be a large drop in speed until the flux can be
restored to its normal level. If Flux Command No Load is set higher than Flux Command Base Speed, the flux
command will not vary with load.
Note: For Bulletin 1557M drives, this parameter is internally limited to 0.600 pu maximum.