Rockwell Automation 7000 PowerFlex Medium Voltage (B Frame) Commissioning - ForGe (PanelView 550) - Manual (Page 104)

100 Rockwell Automation Publication 7000-IN006B-EN-P - May 2013
Chapter 5 Commissioning the Drive
3. Start the drive. The motor accelerates normally up to the speed specified
by parameter Autotune Spd Cmd. Calculate the motor magnetizing
inductance from the measured current and flux feedback. Set the Autotune
L Magn parameter to this value. Set the flux command 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. Repeat
the process until the magnetizing inductance and flux commands stabilise.
4. After completing the flux regulator tuning, the drive waits for a few
seconds and adds a sinusoidal perturbation specified by parameter
Autotune Trq Stp to the torque command, causing the speed to vary. After
the initial transient has decayed (this usually takes a few seconds), measure
the variation in torque and speed and calculate the Total Inertia. Remove
the torque perturbation, and the drive performs a normal stop.
Set the Autotune L Magn (221) parameter to measure magnetizing inductance.
Set the FlxCmd RatedLoad parameter in the Flux Control Group to a value that
produces rated voltage at rated speed and load. Calculate the value of parameter
Autotune T Rotor from parameters Lm Rated and Rated Motor RPM (which
gives the rated slip).
If the auto-tuning is successful:
• set Lm Rated (131) in Motor Model equal to the Autotune L Magn,
• set T Rotor (P132) in Motor Model equal to Autotune T Rotor and
recalculate the flux regulator gains. and
• set Total Inertia (82) in Speed Control equal to Autotune Inertia and
calculate regulator gains
If the auto-tuning fails then a warning is issued indicating the cause of the failure.
Following are the list of possible warnings:
• L Magnetize Low - indicates that the measured value of magnetizing
inductance is less than 1.0 pu. This warning indicates an unusually low
value of magnetizing inductance. This may occur if the motor is much
larger than the drive and the nameplate parameters do not correspond to
the actual motor ratings.
• L Magnetize High - indicates that the measured value of magnetizing
inductance is greater than 10.0 pu. This warning indicates an unusually
high value of magnetizing inductance. This may occur if the motor is much
smaller than the drive, and the nameplate parameters do not correspond to
the actual motor ratings. Tune the flux regulator using the manual method
described below.
• T Rotor Low - indicates that the calculated value of rotor time constant is
less than 0.2 seconds. This is caused by a value of Lm Rated or Rated
Motor RPM which is too low.
• T Rotor High - indicates that the calculated value of rotor time constant is
greater than 5.0 seconds. This is caused by a value of Lm Rated or Rated
Motor RPM which is too high.