Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 227)

COMMISSIONING 9-27
1557-UM050F-EN-P – June 2013
Commutation Inductance Manual Tuning
1.
Set parameter "Test mode" in “P Feature Select“ to 2 to enter dc current test mode.
Current Control Parameter Screen
2.
Set parameter "Idc command test" in “P Current Control” to 0.400 pu.
3.
Set parameter "L commutation" i n “P Current Control” to an initial value of 0.05 pu.
4.
Connect an oscilloscope to the test points labeled V12 and F12 on the line converter control board. Two
sine waves of approximately equal amplitude should be seen, with the reconstructed line voltage F12
lagging the unfiltered voltage V12 by 90 degrees. Adjust the triggering and time base to display the
positive half cycle of V12 with a scale of 20 degrees per major division.
5.
Start the drive. The dc link current will rise to 0.4 pu. Commutation notches will appear in the unfiltered
line voltage V12 as shown in the figure. Some distortion will appear in the reconstructed voltage F12
around the zero crossings.
6.
Measure the average width in degrees of the commutation notch nearest the peak of the V12 waveform
as seen in the following figures.
7.
Record the values of the variables "V line", and "Idc reference” in “V Current control”
8.
Calculate the commutation inductance using the following formula:
L commutation = V line x sin (notch width) / Idc reference
9.
Set parameter "L commutation" to the calculated value. If there was visible distortion in the reconstructed
voltage F12, the distortion should decrease. If the distortion increases, it is possible that the polarity of
the line current feedback is backwards.