Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 221)

Commissioning 4-67
7000 “A” Frame 7000A-RM001A-EN-P – January 2011
The other aspect of flux control is the variation of motor flux with
speed. This is determined by two parameters:
1. Base Speed in Flux Control
2. FlxCmd RatedLoad in Flux Control
In most applications, the motor runs at constant flux below rated speed
and constant voltage above rated speed. The motor flux is normally set
to a level that provides rated voltage at rated speed and full load. The
flux level required to achieve this is a function of the motor parameters.
The flux regulator auto-tuning determines a value of rotor flux that
should provide rated motor voltage at full load and rated speed, and sets
the flux command parameter to this value.
• Speed Regulator
The tuning of the speed regulator is determined by two parameters in
the Speed Control group:
1. SpdReg Bandwidth
2. Total Inertia
Parameter
SpdReg Bandwidth is set to a value determined by the
requirements of the application, but parameter Total Inertia is usually
unknown and must be measured. The auto-tuning determines the
total inertia by measuring the change in speed that occurs when a
low frequency sinusoidal torque perturbation is applied to the motor.
The inertia measurement is not affected by the load torque as long as
the drive does not hit torque limit. Do not disconnect the driven load
from the motor, as it is the total inertia of motor and load that is
being measured.
The following procedure should be used to perform FluxSpeed Reg
auto-tuning:
FluxSpeed Reg Auto-tuning [Induction Motor]
1. Ensure that parameters Rated Motor RPM in Motor Ratings and L
Total Leakage in Motor Model are set to the correct value. Ensure
that parameters Autotune Spd Cmd and Autotune Trq Stp in
Autotune are set to default values.
2. Set parameter Autotune Select in Autotuning to FluxSpeed Reg.
3. Start the drive. The motor accelerates normally up to the speed
specified by parameter Autotune Spd Cmd. The motor magnetizing
inductance is calculated from the measured current and flux
feedback and parameter Autotune L Magn is set to this value. The
flux command is then set to a value that should produce rated
voltage at rated speed and load. The resulting change in the flux
level may cause the magnetizing inductance to change. This
process is repeated until the magnetizing inductance and flux
commands stabilise.