Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 20)

20 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 1 Drive Configuration
Modulation mode is default at space vector only because 2-phase modulation will
degrade the filter’s performance.
Application Considerations
Whatever the device the user wants to connect to the drive by using the
adjustable voltage feature, that device has some type of rating associated with it.
As a minimum it needs to have a current rating and voltage rating. Drive selection
is based on those ratings.
Sizing
First, consider the voltage rating of the drive. Determine what the available line
voltage is and select a drive voltage rating to match. Next, select a drive that
supplies the current necessary for the device’s rating.
Single Phase Output
Consult Rockwell Automation before configuring a drive for single phase
adjustable voltage output. Derating of the drive is necessary because of stress on
the DC bus capacitor or the IGBT switching losses. When PWM is applied to a
resistor, the current changes state following the voltage. For each PWM voltage
pulse the current is pulsing the same way. This rapid change in current is not
designed into the IGBT selection for the drive. Therefore, some sort of derating
needs to be applied. Somewhere around 67% derating. When in this mode, actual
losses must be measured to determine a derating percentage. Adding a reactor in
series with the resistor can help by adding inductance and rounding off the
corners of the current pulses. Depending on how much inductance is added, the
waveform can look like a sine wave.
60 Start Acc Boost 0 Set if there are DC offset voltages at load
transformer input windings.
61 Run Boost 0
62 Break Voltage 0
63 Break Frequency 0
420 Drive OL Mode 1 “Reduce CLmt” Drive OL mode is set for reduce current limit, and
not the PWM frequency as it must remain fixed.
1154 DC Offset Ctrl 1 “Enable” This turns off any offset control programmed in the
firmware.
IMPORTANT Do not autotune.
Parameter No. Parameter Name Setting Description