Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 23)

Overview of Drive 1-7
7000 “A” Frame 7000A-RM001A-EN-P – January 2011
SGCT Features and Benefits An SGCT is a thyristor with an integrated gate drive. Positioning the
gate drive close to the SGCT as shown in Figure 1.4, creates a low
inductance path that provides more efficient and uniform gating of
the device. As a result, the device is better suited to handle the
fluctuating levels of voltage and current while it is switching on and
off during gating.
An SGCT has low conduction and switching losses, low failure rate,
and double sided cooling for low thermal stress. The SGCT achieves
voltage blocking capability in both forward and reverse directions up
to 6500 volts by a NPT (Non-Punch-Through) structure and nearly
symmetrical pnp transistor in the wafer, while the current is
unidirectional.
Implementing SGCTs in the PowerFlex 7000 results in significant
advantages including:
1.
Simplification of the snubber design and a reduction in the size
of the snubber capacitor by a factor of 10
2.
Operation at a higher switching frequency (420-540 Hz), hence
reducing the size of passive components (DC link inductor and
motor filter cap) by 50%
3.
Improving performance of the drive
4.
Reduction of component count, hence improving reliability, cost,
and size of the drive
5.
Ease of service
6.
Non-rupture power device to contain any device failure within
the device, eliminating a cascade failure mode.
Figure 1.4 – SGCT with integrated gate drive (left) and unit cell structure (right)