A 6KV/5KA REVERSE CONDUCTING GCT
Y. Yamaguchi*, K. Oota**, K. Kurachi*, F. Tokunoh**, H. Yamaguchi**,
H. Iwamoto**, J. Donlon***, E. Motto***
*Fukuryo Semicon Engineering Corporation, Fukuoka, Japan
** Power Device Division, Mitsubishi Electric Corporation, Fukuoka, Japan
*** Powerex Incorporation, Youngwood, Pennsylvania, US
Abstract- A Reverse Conducting Gate Commutated
Thyristor (RCGCT) rated at 6000 Volts and 5000
Amperes has been developed. Low loss, snubberless turn
off, and high reliability have been achieved using the same
advanced technology that produced the 6000 Volt, 6000
Ampere asymmetric GCT. That is, the GCT part is
realized using MEPLT (Multi Energy Proton Lifetime
control Technology). Now a monolithic low loss Free
Wheel Diode is included on the same wafer. Integration
of the Free Wheel Diode with the GCT on the same wafer
in the same package allows considerable reduction in size,
weight, and assembly complexity. This new device will
contribute to further miniaturization and improved
performance and reliability of high power electronic
systems.
I. INTRODUCTION
The Gate Commutated Thyristor (GCT) developed as an
extension of the Gate Turn-Off Thyristor (GTO) in 1996
when the first device of this type, called a “hard-driven GTO”
at that time, began customer operation in a 100MVA railway
intertie in Bremen [1]. Since then, these devices have proven
to have excellent reliability [10], technological innovations
have boosted the performance of GCT converters, and new
devices have opened the door to a wide range of applications.
Today, GCTs are fabricated from 34mm pole face diameter
(4.5kV 340A reverse conducting) to 130mm pole face
diameter (6kV, 6kA asymmetric), and reverse blocking
devices have become available.
To accommodate their need for a special low inductance
gate drive, GCTs were introduced from the beginning as a
module with its appropriate gate drive unit (GDU) included,
creating a new powerful and easy to use building block [2].
The space in a stack close to the GCT is valuable. While
small GCTs could be joined with complete GDUs, GDUs for
high power GCTs became rather bulky. Circuits for on-state
gate current and GDU power supplies often had to receive a
separate housing and location close to the stack not only
consuming space but also releasing significant heat into that
sensitive area.
Building on recent advances in wafer technology, a new
generation of high power GCT has been developed. 6000V x
5000A = 30MVA has become the rating of a single reverse
conducting GCT; a 166% increase in power density over
existing maximum 6000V x 6000A packaged in a GCT with
separate diode. By introduction of the most advanced high
efficiency MOSFET circuitry, a compact low loss GDU has
been developed which can control the new RCGCT without
the need for separate housing or special GDU air cooling.
The technology, design, and characteristics of this new high
power GCT building block are described in the sections
which follow.
II. TECHNOLOGY AND DESIGN
Figure 1 shows a photograph of the new 6kV/5kA
RCGCT wafer. The outer annulus is the GCT part, the inner
diameter is the diode part. The basic configuration and
design of the GCT part is the same as for the 6kV/6kA
asymmetric GCT [11]. The GCT and diode parts are
separated by an isolating depletion region. In addition, a
shallow, high resistivity p+ diffusion is used at the surface to
ensure high reliability. The GCT part achieves a turn-off
current, ITQRM, of 5kA without a snubber and with low loss
by applying MEPLT (Multi energy Proton Life-time control
Fig. 1 Wafer of 6kV/5kA RCGCT
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Technology). The diode part achieved a reduction in loss of
approximately 70% by applying a p+ structure on the n+ side
of a conventional PIN structure. Details of the this diode
design can be found in the ISPSD2000 paper by our coworkers [13]. Figure 2 shows the cross-section of the GCT
unit cell, diode, and separation region. Figure 3 shows the
effect of the MEPLT process on the different structure levels
of the GCT.
Gate Al
Cathode Al
Cathode Al
NE
PB
P
III. CHARACTERISTICS
Figure 4 shows the snubberless turn-off waveforms of
the new RCGCT at anode current IT = 5kA, bus voltage VD =
3.0kV, and junction temperature TJ = 25°C. Figure 5 shows a
typical snubberless turn-off of the integrated diode at load
current IT = 2800A, dIT/dt = 500 A/µs, bus voltage VD =
3000V, and TJ = 125°C. Figures 6 and 7 show typical Eoff
and Erec losses as a function of anode current IT and bus
voltage VD. Table 1 summarizes the main characteristics of
the new RCGCT: Small GCT loss in on-state and switching,
small diode loss especially at reverse recovery, and low
thermal resistance. Additionally, the peak off-state current is
reduced considerably in comparison to a GCT diode
combination, making the new device a good choice for series
connection.
N-
PE
P
N+
Anode Al
N+
+
Diode Part
(Inner Side)
Separation Part
GCT Part
(Outer Side)
Fig. 2 Cross-section of GCT unit cell, diode, and separation
region
NE
PB
PB
Proton Energy Small
1
2
Proton Energy large
N-
PE
3
N+
Proton Energy Small
Relative Comparison of Proton Dose
Section
Note:
Recovery characteristic
Loss
Snap
1
+
+
2
+
3
/
‘ + ’ has a beneficial good effect
‘ - ‘ has a detrimental effect
‘ / ’ has no effect
Turn-off characteristic
Loss
/
+
+
The p+ structure improves
these.
Fig. 3 MEPLT Process effects
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ts=2µs
IT=5000A
VD=3000V
Fig. 4 Snubberless Turn-off Waveform
Fig. 5 Snubberless Diode Turn-off
Waveform
Eof f vs IT, VD
Ere c vs IF,VR
Typical
Typic a l
25
5
Condition:
Condit ion:
Tj =125deg
20
Cc =6uF
VD3000V
Tj =125de g
4
Lc =0. 4uH
Cc =6uF
Lc =0.4uH
3
VD 2000V
Erec [J]
Eoff [J]
15
VD 1000V
10
VR 3000V
AL =5.7uH
VR 2000V
2
1
5
VR 1000V
0
0
0
0
1000
2000
3000
4000
1000
2000
Fig. 8 New GDU with GC GCT
4000
IF [ A]
IT [A]
Fig. 6 Eoff vs. IT, VD
3000
5000
Fig. 7 Erec vs. IT, VD
Fig. 9: Total power consumption (dashed lines) and power
loss (solid lines) of the new GDU in 2-level operation.
Curves are shown for switching frequency fs =100Hz,
200Hz and 500Hz at duty = 50%.
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Table 1 Main Characteristics
Item
Characteristics
Condition
Controllable
VD=3000V
5000A
turn-off current
diGQ/dt=10000A/µs
Peak off-state
>6000V
VGR=-2V
voltage
Peak off-state
100mA
VDM=6000V, Tj=125°C
current
Peak reverse
10mA
VRG=21V, Tj=125°C
current
Eon
0.4J/P
IT=2800A, VD=3000V
Eoff
12J/P
IT=2800A, VD=3000V
Erec
2.5J/P
IT=2800A, VD=3000V
On-state voltage
3.0V
IT=2800A,Tj=125°C
Forward voltage
4.5V
IF=2800A,Tj=125°C
Rth GCT part
0.0075°C/W
―
Diode part
0.0082°C/W
Table 2 Features of Selected High Power Devices
Peak off-state voltage
Controllable turn-off current
DC voltage for 100 FIT
Peak off-state current
GCT on-state voltage @ IT
Diode forward voltage @ IT
Eon @ IT, VD
Eoff @ IT
Erec @ IF
Rthj-c GCT/IGBT part
Rthj-c Diode part
Rthc-heatsink GCT/IGBT part
Rthc-heatsink Diode
Rth heatsink GCT/IGBT
Rth heatsink Diode
6” RCGCT
6000V
5000A
3600V
100mA
3.0 V @ 2800A
4.5 V @ 2800A
0.4 J/P @ 2800A, 3kV
12 J/P @ 2800A, 3kV
2.5 J/P @ 2800A, 3kV
7.5 K/kW
8.2 K/kW
2 K/kW
2 K/kW
7 K/kW
6.5 K/kW
4” GCT
6000V
4000A
3600V
3.8V @ 4000A
15 J/P @ 4000A, 3kV
10 K/kW
3 K/kW
8 K/kW
IGBT module
4500V
1800A (2*900A)
2800V
90mA
4.2V @ 1500A
4.8V @ 1500A
2.2 J/P @ 500A, 2250V
1.8 J/P @ 500A, 2250V
0.66 J/P @ 500A, 2250V
10 K/kW
20 K/kW
10.5 K/kW
21 K/kW
8 K/kW
16 K/kW
3-phase 2-level Inverter Operation
VDC-link, 500Hz
Irms, cos Φ = 1
Pout, cos Φ = 1
Irms, cos Φ = -1
Pout, cos Φ = -1
3600V
1900A
9.2MW
1740A
8.25MW
* Pole piece diameter of 6” RCGCT is 130mm
3600V
1760A
8.46MW
2250V
860A
2.58MW
810A
2.43MW
** Mitsubishi IGBT module CM900HB-90H footprint is 190mm x 140mm.
A new low loss Gate Drive Unit was developed for the
RCGCT [14]. Figure 8 shows the Turn-on/Turn-off part of
the new GDU with the RCGCT. The IGon, low pulse,
control, and power supply section is mounted on top of the
Turn-on/Turn-off circuit creating a very compact GDU.
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The new GDU achieves low power consumption as
shown in Figure 9. A large fraction of this power is
transferred to the GCT and a total loss of less than 12W is
expected.
Table 2 presents a comparative overview of the main
features various actual high power devices. The output
capability of a 3-phase 2-level inverter using each of these
devices is shown in the lower part of the table. The inverter
operation is based on assumptions of inlet water temperature
TW = 40°C, operating junction temperature of TJ=125°C, and
all devices cooled using a very efficient all copper heat sink.
It is seen that the new 6 inch RCGCT provides a well
balanced set of characteristics for the highest output
capability.
The Integration of the Free Wheel Diode with the GCT
on the same wafer in the same package allows considerable
reduction in size, weight, and assembly complexity. This can
be envisioned by examining the three schematic
implementations of one phase of a voltage source inverter
using a reverse blocking GTO, a reverse blocking GCT, and
the new reverse conducting GCT as shown in Figure 10. The
significant reduction in component count is apparent. Figures
11 and 12 then show the actual size and weight reduction
achievable with the new Reverse Conducting GCT.
IV. CONCLUSION
A new power electronic building block – RCGCT and
GDU – has been developed. It combines high turn-off
capability and low loss and is specially dedicated to high
power applications like steel rolling mill drives, SVC, UPFC,
and interties. This new building block will further enhance
compactness, reliability, and modularity of high power
electronic systems.
[5] Data Sheet of Gate Driver GU-C40, Mitsubishi Electric
Corporation, Aug. 1998.
[6] K. Satoh, et al., “6kV/4kA Gate Commutated Turn-Off
Thyristor with Operation DC Voltage at 3.6kV”, ISPSD
1998.
[7] K. Kurachi, et al., “GCT Thyristor – A Novel Approach
to High Power Conversion”, PCIM Inter 1998.
[8] M. Yamamoto, et. al., “GCT Thyristor and Gate Drive
Circuit”, PESC 1998.
[9] J.F. Donlon, E.R. Motto, M. Yamamoto, T. Iida, “A
New Gate Commutated Turn-Off Thyristor and
Companion Diode for High Power Applications”, IEEE
IAS Conference 1998, pp. 873-880.
[10] H. Gruening, D. Leonard, “Leistungshalbleiter und
Schaltungstechnik fuer Bahnstromanwendungen der
Zukunft”, Elektrische Bahnen 97, R. Oldenburg Verlag
1999, Vol. 1-2, pp. 42-48.
[11] K. Satoh, K. Morishita, Y. Yamaguchi, H. Hirano, H.
Iwamoto, A. Kawakami, “New Design Approach For
Ultra High Power GCT Thyristor“, Proceedings of IEEE
ISPSD 1999, pp. 351-354.
[12] M. Mukunoki, K. Takao, H. Yamaguchi, Y. Shimomura,
F. Mizohata, S. Mizoguchi, M. Koyama, “Highefficiency large-capacity three-level GCT Inverter”, IEEJ
Conference Proceedings SPC-00-43, 2000, pp. 35-40.
[13] K. Satoh, K. Morishita, Y. Yamaguchi, N. Hirano, H.
Iwamoto, A. Kawakami, “A Newly Structured High
Voltage Diode Highlighting Oscillation Free Function In
Recovery Process”, Proceedings of the ISPSD 2000, pp.
249-252
[14] H. Gruening, T. Tsuchiya, K. Satoh, Y. Yamaguchi, F.
Mizohata, K. Takao, “6kV 5kA RCGCT with Advanced
Gate Drive Unit”, Proceedings of the ISPSD 2001, pp.
133-136.
REFERENCES
[1] P.K.Steimer, H. Gruening, J. Werninger, D. Schroeder,
“State-of-the-Art Verification of the Hard Driven GTO
Inverter Development for a 100 MVA Intertie”,
Proceedings of IEEE PESC, Baveno, 1996, pp. 14011407
[2] H. Gruening, B. Oedegard, A. Weber, E. Carroll, S.
Eicher, “High Power Hard-Driven GTO Module for 4.5
kV/3kA Snubberless Operation,” in Conf. Rec,
PCIM’96, 1996, pp. 169-183
[3] K. Satoh, et al. , “A New High Power Device GCT (Gate
Commutated Turn-off) Thyristor”, EPE 1997
[4] M. Matsushita, T. Ogura, I. Omura, N. Ninomiya, H.
Ohashi, Realizing High Frequency Operation”, ISPSD
1997, pp. 247-250.
0-7803-7114-3/01/$10.00 (C) 2001
Snubber circuit
C lamp circuit
R DGTO
RDGC T
FR D
RD GTO
RCGCT
RCGCT
Type
(
RD GC T Type
FG6000AU -120DA
FGC 6000AX -120DS
FGC R5000AX -120DS
Fig. 10 Implementations of a Voltage Source Inverter Phase
Device Volum e
1400
1200
Diode + RDGCT type
Volume [cm3]
1000
800
600
400
RCGCT type
200
0
0
5
10
15
Fig. 11
20
M VA
25
Device Volume vs. Power Output
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30
35
40
Device W eight
7
6
Weight [Kg]
5
Diode + RDGCT type
4
3
RCG CT type
2
1
0
0
5
10
15
Fig. 12
20
M VA
25
Device Weight vs. Power Output
0-7803-7114-3/01/$10.00 (C) 2001
30
35
40