Vacon NX series Applications Manual page 311

PARAMETER DESCRIPTIONS
NOTE!
The actual switching frequency might be reduced down to 1.5kHz by thermal
management functions. This has to be considered when using sine wave filters or
other output filters with a low resonance frequency. See parameters ID1084 and
ID655.
602 FIELD WEAKENING POINT 234567 (2.6.4)
The field weakening point is the output frequency at which the output voltage reaches the
field weakening point voltage.
603 VOLTAGE AT FIELD WEAKENING POINT 234567 (2.6.5)
Above the frequency at the field weakening point, the output voltage stays at the set
maximum value. Below the frequency at the field weakening point, the U/f curve parameters
control the output voltage. See the parameters ID109, ID108, ID604 and ID605.
When you set the parameters ID110 and ID111 (nominal voltage and nominal frequency of the
motor), the parameters ID602 and ID603 automatically receive related values. To have
different values for the field weakening point and the maximum output voltage, change these
parameters only after you set the parameters P3.1.1.1 and P3.1.1.2.
604 U/F CURVE, MIDDLE POINT FREQUENCY 234567 (2.6.6)
If the value of ID108 is programmable, this parameter gives the middle point frequency of the
curve. See Fig. 24 Linear and squared change of the motor voltage and parameter ID605.
605 U/F CURVE, MIDDLE POINT VOLTAGE 234567 (2.6.7)
If the value of ID108 is programmable, this parameter gives the middle point voltage of the
curve. See Chapter 108 U/F ratio selection 234567 (2.6.3).
606 OUTPUT VOLTAGE AT ZERO FREQUENCY 234567 (2.6.8)
This parameter gives the zero frequency voltage of the U/f curve. The default value is
different for different unit sizes.
NOTE!
If the value of parameter ID108 is changed this parameter is set to zero. See Fig. 25
The programmable U/f curve.
607 OVERVOLTAGE CONTROLLER 234567 (2.6.10)
When you enable ID607 or ID608, the controllers start to monitor the changes in the supply
voltage. The controllers change the output frequency if it becomes too high or too low.
To stop the operation of the undervoltage and the overvoltage controllers, disable these 2
parameters. This is useful if the supply voltage changes more than -15% to +10%, and if the
application does not tolerate the operation of the controllers.
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