Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C-Frame) - ForGe Control - Manual (Page 252)

252 Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
Chapter 4 Commissioning
The field current reference is then held constant and the response of the flux to
changes in stator magnetizing current is measured by stepping “Ix command” up
and down at regular intervals. The size of the step in the stator current is specified
by parameter
Autotune Isd Step. The step response measurement takes about 3
minutes. During this step parameter Lmd, T Rotor, Lm Rated will be calculated.
When the motor speed has settled at the commanded value, a sinusoidal
perturbation specified by parameter
Autotune Trq Stp is added to the torque
command, causing the speed to vary. After the initial transient has decayed (this
usually takes a few seconds), the variation in torque and speed are measured and
used to calculate the total inertia. The torque perturbation is then removed and
the drive performs a normal stop.
Parameter FlxCmd RatedLoad in Flux Control is set to a value calculated to
produce rated voltage at rated speed and load. The value of parameters Autotune
T Rotor and Autotune Lmd are calculated from the step response data.
If the flux regulator auto-tuning is successful, then parameter Lm Rated in Motor
Model is set equal to Autotune L Magn, parameter T Rotor in Motor Model is set
equal to
Autotune T Rotor, and parameter Lmd in Motor Model is set equal to
Autotune Lmd. Parameter Total Inertia(63) in Speed Control is set equal to
Autotune Inertia. If the flux regulator auto-tuning fails a warning is issued
indicating the cause of the failure.
L Magnetize Low – indicates that the measured value of magnetizing inductance
is less than 1.0 pu. This warning is intended to draw attention to an unusually low
value of magnetizing inductance. The most likely cause is incorrect scaling of the
analog field current reference.
L Magnetize High – indicates that the measured value of magnetizing
inductance is greater then 15.0 pu. This warning is intended to draw attention to
an unusually high value of magnetizing inductance. The most likely cause is
incorrect scaling of the analog field current reference.
T Rotor Low – indicates that the calculated value of rotor time constant is less
than 0.2 seconds
T Rotor High – indicates that the calculated value of rotor time constant is
greater than 5.0 seconds.
Regulator Limit - indicates that the torque command was greater than
Trq Lmt Motoring or Trq Lmt Braking. The measured inertia value is invalid.
Parameter
Autotune Trq Stp or parameter Autotune Spd Cmd must be set to a
lower value and the test repeated.
Tuning Abort - indicates that the deviation in motor speed was greater than
10 Hz. The measured inertia value is invalid. Parameter Autotune Trq Stp must be
set to a lower value and the test repeated.
Inertia High - indicates that the measured total inertia is greater than 20.0
seconds. This warning is intended to draw attention to an unusually high inertia