Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) Commissioning - ForGe Control User Manual
Page 97
Rockwell Automation Publication 7000-IN012B-EN-P - June 2014
97
Commissioning the Drive Chapter 4
T DC Link (P#115) Manual Tuning
Determine an appropriate value for the T DC Link parameter from the current
regulator step response while operating in DC Current test mode. Use the
following procedure:
1.
Ensure you set all parameters in the Drive Hardware and Motor Ratings
groups to the correct values. Otherwise, the calculated value of parameter
T DC Link in Current Control will be incorrect.
2.
Set parameter Operating Mode in the Feature Select to DC Current to
enter the test mode.
3.
Set parameter Idc Test Command in Current Control to 0.225 pu for
AFE rectifier drives and 0.400 pu for SCR drives.
4.
Set parameter CurReg Bandwidth in Current Control to 100 rad/s. A
lower than the normal bandwidth makes the step response easier to
measure.
5.
Set parameter T DC Link in Current Control to 0.020 sec, which is at the
low end of the normal range of values and should produce an under-
damped response.
6.
Assign parameters Idc Reference and Idc Feedback in the Current Control
group to 2 DPM test points e.g. RTP1 and RTP2. This process is similar to
the meter assignments described earlier. Use an oscilloscope to view the
results.
7.
Start the drive. Set parameter Idc Ref Step in Current Control to 0.075 pu
for AFE rectifier drive and 0.200 pu for SCR drives. The dc link current
will step up and down by this amount at regular intervals.
8.
Adjust the scope to trigger on the rising edge of the dc current reference
and observe the dc current feedback on the other channel. The step
response may have noticeable overshoot, indicating that the dc link time
constant is too low.
9.
Adjust the T DC Link parameter until the current feedback rises to ~63%
of its final value in 10 ms as shown in
. The
overshoot should reasonably small. Increasing T DC Link causes the rise
time to increase. Since the desired step response is slightly under-damped,
do not increase the T DC Link beyond the value at which the overshoot
disappears.