Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 22)

1-6 Overview of Drive
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
Motor Compatibility The PowerFlex 7000 achieves near sinusoidal current and voltage
waveforms to the motor, resulting in no significant additional heating
or insulation stress. Temperature rise in the motor connected to the
VFD is typically 3 °C (5.4 °F) higher compared to across-the-line
operation. Voltage waveform has dv/dt of less than 10 volts per
microsecond. Reflected wave and dv/dt issues often associated with
VSI (voltage source inverter) drives do not exist with the PowerFlex
7000. Typical motor waveforms are shown in Figure 1.3. These
motor friendly waveforms are achieved by utilizing a selective
harmonic elimination (SHE) pattern in the inverter to eliminate
major order harmonics, in conjunction with a small output capacitor
(integral to the drive) to eliminate harmonics at higher speeds.
Standard motors are compatible without de-rating, even on retrofit
applications.
Motor cable distance is virtually unlimited. This technology is capable
of controlling motors up to 15 km (9.3 miles) away from the drive.
300.00
200.00
100.00
0.00
-100.00
-200.00
-300.00
10.00K
7.50K
5.00K
2.50K
0.00K
-2.50K
-5.00K
-7.50K
-10.00K
100.00 110.00 120.00 130.00
TIME (ms)
140.00 150.00
Arms
Vrms
Figure 1.3 – Motor waveforms @ full load, full speed
Motor current
Motor voltage