Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control - Manual (Page 296)

Commissioning 4-91
7000 “C” Frame 7000L-UM300I-EN-P – Juen 2013
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 magnetizing current
reference and the flux feedback and parameter "Autotune Lm" 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 command stabilize. If a position encoder is fitted to the
motor, the angle between the measured flux and the encoder zero is
measured and parameter “Encoder offset” is adjusted to align the
encoder with the motor flux.
4. 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. When the measurement is complete, the drive
performs a normal stop.
Parameter "Autotune Lm" is set to the measured magnetizing
inductance and parameter "Autotune Select" is set to Off. Parameter
"Flux Command Base Speed" in "Flux Command" 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 autotuning is successful, then parameter "L
magnetizing" in "Motor Model" is set equal to "Autotune Lm",
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”. If the flux regulator autotuning fails then parameters
"L magnetizing", “Lmd”, and "T rotor" are not changed and a warning
is issued indicating the cause of the failure.
L magn low – indicates that the measured value of magnetizing
inductance is less then 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 magn 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.