Topology – Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C-Frame) - ForGe Control User Manual
Page 17
Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
17
Overview of Drive
Chapter 1
–
Common modular design for rectifier / inverter
–
Same concept as air-cooled drive for front access, easy component
replacement, and no special tools
–
5...10 minutes to replace main power devices
–
No need to remove any cooling lines for device replacement
–
Reduced manufacturing time for faster delivery and lower cost
• Keyed mechanical interlock
–
Interlocked with main disconnect means to prevent unsafe access to
medium voltage section
Topology
The PowerFlex 7000L utilizes a Pulse Width Modulated (PWM) – Current
Source Inverter (CSI) for the machine side converter as shown in
. 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. Semiconductor fuses are not
required for the power structure due to the current limiting DC link inductor.
With 6500VPIV 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 7000L has the additional benefit of inherent regenerative braking
for applications where the load is overhauling the motor (i.e. downhill conveyors,
etc.), or where high inertia loads (i.e. fans, etc.) need to be slowed down quickly.
Symmetrical Gate Commutated Thyristors (SGCTs) are used for machine
converter switches. Silicon-controlled rectifiers (SCRs) (for 18 Pulse) or SGCTs
(for AFE rectifiers) are used for the line converter switches. An AFE
configuration is shown in
.
The PowerFlex 7000L provides a selectable option for enhanced torque control
capabilities and increased dynamic control performance. This High Performance
Torque Control (HPTC) feature delivers 100% torque at zero speed and
provides torque control through zero speed with smooth direction transition.
Figure 1 - AFE Rectifier (4160 Volt)
2U (X1)
2V (X2)
2W (X3)
SGCT’s
LINE CONVERTER
DC LINK
L+
M+
SGCT’s
MACHINE CONVERTER
U (T1)
V (T2)
W (T3)
L-
M-
1U
1V
1W
LR