Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 228)

4-74 Commissioning
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
• Speed Regulator
Refer details given for Induction motor section.
Note: If a position encoder is fitted to the motor, the FluxSpeed
regulator auto-tuning is performed with the encoder feedback turned
off because it is assumed that the encoder has not been aligned with
the rotor axis yet. Since less starting torque is produced with the
encoder feedback off, this test should be performed with reduced
load. The encoder offset measurement is also most accurate with no
load on the motor.
FluxSpeed regulator Auto-tuning [Synchronous Motor]
The FluxSpeed regulator is tuned with the motor running at constant
speed using the following procedure:
1. Ensure that the analog reference for the field current has been set
up as described previously, and that parameter L Total Leakage has
been set to the correct value.
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 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.
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.
Tuning Procedure (cont.)