Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 228)

9-28 COMMISSIONING
1557-UM050F-EN-P – June 2013
COMMUTATION INDUCTANCE TUNED CORRECTLY COMMUTATION INDUCTANCE INCORRECTLY TUNED
10.
Set parameter "Idc command test" to 0.800 pu. The dc current will increase and the commutation
notches will become much larger.
11.
Repeat steps 6 to 9. The higher current will produce a more accurate measurement of the commutation
inductance.
12.
Confirm that the commutation inductance is set to the correct value by increasing the horizontal and
vertical magnification and observing the zero crossing of reconstructed voltage F12. Because the line
converter firing angle is about 90 degrees, the commutation notch occurs near the zero crossing of the
reconstructed voltage. The signal should be a straight line through the zero crossing with almost no
visible distortion. Either increasing or decreasing parameter “ L Commutation“ should cause the distortion
to increase.
13.
Stop the drive. Set parameters “Test mode” and "Idc command test" to zero.
2. Current Regulator
The tuning of the current regulator is controlled by three parameters in the “P Current Control" group:
1. “Curreg bandwidth”
2. "L dc link”
3. "T dc link"
Of these three parameters, inductance “L dc link“ is calculated from its nameplate rating, the current regulator
bandwidth should be set to its default value of 200 rad/sec, and only “T dc link” is unknown and must be
measured. Although the current regulator was tuned during factory test, it should be retuned during
commissioning because the dc link time constant is affected by the impedance of the drive input transformer.
Current Regulator Autotuning
The current regulator can be tuned automatically using the following procedure:
1.
Ensure that the parameters in the "P Nameplate" group have been set to the correct values, otherwise the
calculated value of parameter "L dc link" in "P Current Control" will not be correct.
2.
Set parameter "Autotune select" in "P Autotune" to 2. The drive will go into dc current test mode. The
current re
gulator bandwidth is temporarily set to the value specified by parameter "Autotune Idc BW”. The
dc current command is set to the value specified by parameter "Autotune Idc cmd". The dc current step is
set to the value specified by parameter "Autotune Idc stp".