Rockwell Automation 20P PowerFlex Digital DC Drive - Manual (Page 302)

302 Rockwell Automation Publication 20P-UM001I-EN-P - February 2013
Appendix C Application Notes
Manually Adjusting the Current Regulator Tune Settings
While the drive is operating, the value of Par 587 [I Reg Error] is updated in
response to changes in the current output to the motor. By manually applying
current steps to the motor, this parameter can be used as an indication whether
the current regulator in the drive is correctly tuned. Ideally, the value should be as
near to zero as possible, but values between -40 and +40 are acceptable during
normal operation (because the drive is responding to changing current demands).
Manually tuning the Current Regulator will attempt to have Par 587 [I Reg
Error] reach its lowest value in response to applied steps in current to the motor.
Adjustments to Par 587 [I Reg Error] are made by changing Par 454 [Arm
Inductance] and stepping the current to the motor. Par 587 [I Reg Error] values
are only valid when the drive is operating under at least a 30% current load. The
manual tuning procedure will progress through larger current steps up to 100%.
Par 454 [Arm Inductance] and Par 453 [Arm Resistance] are the current
regulator tuning parameters and typically will not match motor data sheets
values.
Manual Current Loop Tuning
When attempting to manually tune the current loop, the current reference will be
stepped to values that may cause the motor to rotate even while the field is
disabled (residual flux). If possible, the motor armature shaft should be locked to
prevent rotation or decrease the maximum amplitude of current applied per step
to minimize armature movement. Not locking the armature is optional only
when external speed measurement is in use (i.e., encoder or tachometer).
Armature rotation will interfere with getting acceptable tuning values. Be sure to
record all original parameter values that are changed as part of configuration for
this test.
1. Disable the field regulator by setting Par 497 [Field Reg Enable] to 0
“Disabled”.
Note: For firmware version 3.001 and later: Set Par 469 [Field Mode Sel]
to 2 “External” and Par 414 [Fdbk Device Type] to 1 “Encoder” (a Type 2
alarm will be generated if Par 414 is set to 3 “Armature”).
2. Verify that Par 351 [Field Current] is set to zero (0 or < 0.05 A).
3. Disable the speed regulator by setting Par 242 [Speed Reg En] to 0
"Disabled".
4. Set/verify that Parameters 7 [Current Limit], 8 [Current Lim Pos] and 9
[Current Lim Neg] are at 100%.
5. Set Par 453 [Arm Resistance], calculated as:
(Par 175 [Rated Motor Volt] / Par 179 [Nom Mtr Arm Amps]) x 0.04
6. Set Par 454 [Arm Inductance] to the minimum value (based on drive size).
7. Set Par 39 [Torque Ref ] to 30%. (this is a percentage relative to Par 179
[Nom Mtr Arm Amps]).