Rockwell Automation 7000A PowerFlex Medium Voltage Drive (A-Frame) - Classic Control - Manual (Page 21)

Overview of Drive 1-3
7000 “A” Frame 7000A-UM150F-EN-P – June 2013
Topology
The PowerFlex 7000 “A” Frame utilizes a Pulse Width Modulated
(PWM) – Current Source Inverter (CSI) for the machine side
converter as shown in Figure 1.1. This topology offers a simple,
reliable, cost effective power structure that is easy to apply to a wide
voltage and power range. The power semiconductor switches used
are easy-to-series for any medium voltage level. Semi-conductor
fuses are not required for the power structure due to the current
limiting DC link inductor.
With 6500 volt PIV rated power semiconductor devices, the number
of inverter components is kept to a minimum. For example, only six
inverter switching devices are required at 2400V, 12 at 3300-4160V,
and 18 at 6600V.
The PowerFlex 7000 “A” Frame has the additional benefit of
inherent regenerative braking for applications where the load is
overhauling the motor, or where high inertia loads need to be slowed
down quickly. Symmetrical Gate Commutated Thyristors (SGCTs)
are used for machine converter switches. Silicon-controlled
rectifiers (SCRs) (for 6 pulse) or SGCTs (for Active Front End
rectifier) are used for the line converter switches.
CONVERTER
LINE
L- M-
DC LINK
L+ M+
MACHINE
CONVERTER
2U (X1)
2V (X2)
2W (X3)
U (T1)
V (T2)
W (T3)
SCRs SGCTs
CONVERTER
LINE
L- M-
DC LINK
L+ M+
MACHINE
CONVERTER
2U (X1)
2V (X2)
2W (X3)
U (T1)
V (T2)
W (T3)
SCRs SGCTs
Figure 1.1 – PWM-CSI AC Drive