Adjustable Flux Demand
Note
This feature is currently not implemented in NXGPro+
Some motors require less ux at startup to prevent saturation, some applications require
increased torque at start or low speed and hence a higher than rated ux to start. Another
possibility is increasing ux below base speed of a motor to allow higher torque up to rated
speed with the motor achieving full voltage at less than rated speed – essentially changing the
Volts/Hz slope of the ux.
By utilizing xed speed points that are distributed with a higher concentration in the lower speed
regions, a ux table can be created to address all these needs. The user sets the ux at each
speed setpoint to create the desired starting curve.
Each of 12 speed setpoints are identied in the menu as "Flux @ xx% spd" in PU ux demand. The
range is from 0.0% (0.0) to 40% (0.4) with the default ux set to 1.0 at each setpoint. The 13th
speed setpoint is at 50% and is set by the original parameter "Flux Demand" (3150). Refer to
table Flux Table Menu (3131) Parameters.
When enabled by the parameter "Flux Table Enable" (3132), the ux demand it set by the ux
demand at each speed setpoint and linear interpolation is used to address points in between.
'On use' is for reduced ux on startup. The table will extend in the lower speed regions up to 50%
speed. There are no additional ux table entries above this point. See gure Flux Reduction.
0
0.2
0.4
0.6
0.8
1
1.2
0 7 14 21 28 35 42 49 56 63 70 77 84 91 98
Figure 6-3 Flux Reductiom
For some applications, a ux boost rather than ux weakening is desired. See gure Flux Boost.
Parameter Assignment/Addressing
6.8 Options for Stability Menu (3) - rst half
NXGPro+ Control Manual
Operating Manual, A5E50491925A 131
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