Rockwell Automation 7000 PowerFlex Medium Voltage (B Frame) Commissioning - ForGe (PanelView 550) - Manual (Page 110)

106 Rockwell Automation Publication 7000-IN006B-EN-P - May 2013
Chapter 5 Commissioning the Drive
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 indicates 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 value. For a very high inertia load such as a large fan, this may be a
valid result and parameter Total Inertia should be manually set equal to
Autotune Inertia. However, a high inertia measurement could also be
produced by a value of Autotune Trq Stp which is too low.