22P165-P
Fabrication of power supply with IEGT for TFC of a small fusion device
IEGTを用いた小型核融合装置のTFC電源の製作
Masaharu Soya, Shoich Hatakeyama, Kohei Shibata, Takashi Miyaura,Takanori Isobe, Hiroaki Tsutsui, Shunji Tsuji-Iio, and Ryuichi Shimada
征矢正治, 畠山昭一，柴田浩平，宮浦 崇，磯部高範，筒井広明，飯尾俊二，嶋田隆一
Tokyo Institute of Technology
2-12-1, Oookayama, Meguro-ku, Tokyo 152-8550, Japan
東京工業大学 〒152-8550 東京都目黒区大岡山2-12-1

Our laboratory are making a small fusion tokamak device. This devise need stable toroidal magnetic
field for stady of controll disruption. I achieve stable field using capacitor bank and IEGT. In thissession, the ways and means to this power supply and the result of power sistribution.

1. Introduction
Our laboratory are making a small fusion
tokamak device. This devise need stable toroidal
magnetic field for stady of controll disruption.
Many somall fusion device have problem forflat-top current. Especially, our device is desirable togenerate flat-top current of toroidal magnetic field coil
to confine nearly steady state plasma.

2. Method
The purpose of this study achieves flattop
current with longer than existing capacitor
discharge by using IEGT which is switching
device of high-power.
IEGT developed by TOSHIBA stands forInjection Enhanced Gate Transistor. IEGT has
higher operation voltage and current than
IGBT and higher switching frequency thanGTO. Chart 1 is performance of ST1500GXH21
that is we using IEGT.

with TFC.
In the state ON of IEGT, the capacitor isdischarge through the IEGT, and current isflowing the TFC. On the other hand, in thestate of OFF of IEGT, inductance of TFC drives
the current through a diode. In the state ON ofIEGT, the current follows eq1.In the state OFF,the current follows eq2. i means a current ofTFC. VC means capacitor voltage. L isinductance of TFC. R is resistance of TFC. I0 is
initial value of current of TFC. This circuit
makes flat-top current repeating two states.
The timing of IEGT turn ON/OFF iscalculated in advance on PC, after that calculated
timing is programmed to a micro controller. The
micro controller control IEGT.
We can control the current of TFC by feedback with monitoring the current of TFC. But I
adopt programming in advance because this issimpler control than feed back.

Chart 1 performance of ST1500GXH21VCES
ICPVGESVGE(off)
VCE(sat)CiestONtOFF

4500V
3000A
±20V
Min:3.7V,Max:5.7V
5.0V
200nF
1.3μs
11.5μsFig 1 is circuit figure. The circuit is addedin IEGT with existing method of discharge ofcapacitor, and added in reflux diode in parallel

Fig1 circuit of power supply

ON/OFF make difference flat-top current.
4. Test circuit
In the poster, we’ll show the result of power
supply with IEGT. Before that, we check up
planned system with test circuit. Test circuit isusing IGBT instead of IEGT, and capacitor voltage
is 20V.
Fig4 is result of test circuit. Red curve iscurrent of experiment. Blue curve is current of
numerical simulation. You can see that both
waveforms are similar. This shows that the way isenough to control.

Fig2 Photo IEGT

3. Computer simulation
We simulated by PC this circuit withparameter of a capacitor capacity, a resistance andinductance of TFC that is planned to make. Theseparameters are chart2, and the result of simulation
is fig 3.

Chart2 parameter of simulation
C4mF
VC
4000V
RTFC
1.1orm
LTFC
42.7mHFig4 Result of test circuit

5. Features of this power supply
We wrote in computer simulation, thissystem is possible changing flat-top time withchanging timing of IEGT ON/OFF. This feature
make a various operate patterns.
And this system can apply to many coils tocalculate timing following these equations. But
this can’t apply with a small inductance of coils.
Because of current down and up quickly.
References[1] TOSIBA Revew Vol.63 No.11 (2008)

Fig3 Result of simulation
Blue curve is usually capacitor discharge.
Red curve is large current and short flat-top. Greenis small current and long flat-top. This circuit
makes longer flat-top than usually capacitor
discharge. In addition, changing timing of IEGT