Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) Commissioning - ForGe Control - Manual (Page 94)

94 Rockwell Automation Publication 7000-IN012B-EN-P - June 2014
Chapter 4 Commissioning the Drive
Rectifier
The Rectifier tuning function calculates parameter Input Impedance (P#140)
and T DC Link (P#115) in Current Control group.
Input Impedance
Input Impedance is used in the software reconstruction of the line voltage to
compensate for the drop in the line impedance. It is also used in the calculation of
the line converter retard limit (for SCR rectifiers) to ensure proper operation
under all conditions of line voltage and load current. If the Input Impedance
parameter is not correctly adjusted, the resulting error in the reconstructed line
voltage may cause line synchronization faults and incorrect reading of the
incoming line voltage.
The Input Impedance parameter is tuned with the drive operating in the dc
current test mode. Although the Input Impedance was tuned during factory test,
it must be retuned during commissioning because its value is determined by the
impedance of the input transformer and harmonic filter (if present).
T DC Link
Three parameters control current regulator tuning – two in the Current Control
group, and one in the Drive Hardware group:
• Current regulator bandwidth CurReg Bandwidth
• DC Link time constant T DC Link
• DC Link inductance in per unit DCLnk Induct pu
Inductance DCLnk Induct pu is calculated from its nameplate rating, the current
regulator bandwidth should be set to its default value of 200 rad/s, 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.
The following auto-tune procedure is used to complete the rectifier side tuning:
1. Ensure that the parameters in the Drive Hardware and Motor Ratings
groups have been set to the correct values.
2. Set parameter Autotune Select in the Autotuning parameter group to
Rectifier. The drive will go into DC Current test mode. The current
regulator bandwidth is set to Autotune Idc BW (P#212).