Rockwell Automation 20P PowerFlex Digital DC Drive - Manual (Page 311)

Rockwell Automation Publication 20P-UM001I-EN-P - February 2013 311
Application Notes Appendix C
Tuning the Field Current Curve
The function of the field current curve is to control the actual motor flux and,
subsequently, motor torque if the field goes into an overvoltage condition.
Figure 94 illustrates the relationship between flux and flux current when the field
current curve is defined versus not defined.
Complete the procedures in the order listed below when tuning the field current
curve:
• Field current regulator. See Fine Tuning the Field Current Regulator on
page
304 .
• Field current curve tuning (Flux / if curve)
• Voltage regulator in the field converter. See Fine Tuning the Voltage
Regulator in the Field Converter on page
309 .
Figure 94 - Curve Conversion Flux/Current
Examples:
• Curve A - If the default settings of the drive are retained, the flux current
to flux reference will remain linear when the value of Par 500 [Flux Ref
Pct] changes. For example:
• If Par 467 [Max Fld Curr Pct] / Par 500 [Flux Ref Pct] = 100%,
then Par 234 [Fld Current Pct] / Par 500 [Flux Ref Pct] = Par 280
[Nom Mtr Fld Amps]
• If Par 467 [Max Fld Curr Pct] / Par 500 [Flux Ref Pct] = 50%, then Par
234 [Fld Current Pct] / Par 500 [Flux Ref Pct] = 50% of Par 280 [Nom
Mtr Fld Amps]
Par 234 [Fld Current Pct]
Par 280 [Nom Mtr Fld Amps] @ 100%
Par 916 [Fld Const 90 Pct]
Par 280 [Nom Mtr Fld Amps] @ 50%
Par 918 [Fld Const 40 Pct]
Par 917 [Fld Const 70 Pct]
40% 50% 70% 90% 100%
Curve A
Curve B
Par 500 [Field Ref Pct]