Koichi Matsumoto

Miki Kitajima

Shigeyuki Minami

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Development of High Performance DC Fuse for Electric Vehicle and Its Features
Miki Kitajima 1, Shigeyuki Minami 2, and Koichi Matsumoto 3
 1 Department of Electrical Engineering, Osaka City University, kitajima@em.elec.eng.osaka-cu.ac.jp
2 Department of Electrical Engineering, Osaka City University, minami@ elec.eng.osaka-cu.ac.jp
3 Osaka Fuse Co.,Ltd., koichi@fuse.co.jp
Abstract
The voltage of power circuits used in electric vehicles has increased to 500 V or more.  This shift to higher voltages
is done to reduce current, harness weight and improve motor-controller’s efficiency.  The fuses that protect these
circuits must shut out DC arcs, yet their performance needs improving.  This paper reports the development of a
formidable fuse that coats a thin film of hydrogen strage Titanium on copper foil, and its features.  This new fuse
has shown great potential in protecting high voltage circuits of future electric vehicles, and other high voltage DC
electric devices.
Keywords
electric vehicle fuse, arc discharge, titanium, thermal
spray
1.  INTRODUCTION
It is hard to break high voltage DC arcs.  Because of
this, fuses made with conventional SiO2 powder are un-
reliable for the 500V or more than 1000 V used for elec-
tric vehicles, etc.  To protect electric vehicle harnesses
and electronic circuits such as inverters, a trip time of
about 1 ms is required and development is now an ur-
gent issue.  We already developed a new type of fuse
using hydrogen strage alloy knowing that hydrogen is
effective in breaking arcs [Minami et al., 2003].  Be-
cause it uses a low temperature acting hydrogen storage
alloy, safety and productivity are difficult issues.
Titanium releases hydrogen at about 600℃ and can be
stably impregnated with it, therefore the idea of the new
fuse applied these principles.  By coating the hydroge-
nated Titanium on copper or other fuse, it is hoped that
the hydrogen will cover the arc and thus break it.  Tita-
nium has a high electrical resistance and is unsuited as a
fuse itself.  The fuse body requires a material of high
conductivity such as copper.
It is thought to heat Titanium powder at high voltage
and high current, accelerate it by electromagnetic force
in a hydrogen atmosphere and directly coat the copper
when an appropriate newly plasma gun can be devel-
oped.  It is expected that the hydrogen storage Titanium
could be coated on the surface without melting the cop-
per.  A method for accelerated and melted powder using
electromagnetic force to create a thin film was devel-
oped some time ago by Usuba et al [2002].  Under the
Patent 3331375, the powder itself is ionized and accel-
erated by the electromagnetic force.  Therefore, only
conductive powders can be used.  Also by this method,
the powder must be set in a device each time to dis-
charge, which is not only expensive to make but it also
has not considered Titanium occlusion in hydrogen.
2.  EXPERIMENT METHOD
As a method of fabrication of new-type fuse, it is thought
to place the powder in a vacuum tube and a plume of
gas is injected through a valve by pulsed current, then a
pulsed high  voltage is applied between the two elec-
trodes as shown in Figure 1.  The powder is accelerated
by electromagnetic force based on the gas discharge.
The melted Titanium powder is hit by the cupper coated
ceramics and formed a thin film structure.
A fuse of high speed breaking performance can be made
using Hydrogen storage Titanium powder coated on the
fuse body.  With this film forming method, discharging
occurs because of the injected hydrogen gas.  The pow-
der is then accelerated between the electrodes using the
electromagnetic force generated at that time.  Accord-
Fig. 1  An illustration of the powder injector
ingly, even nonconductive powders can be accelerated
and formed into films.  The method patented by Usuba
et al. [2003] can not use gas.  Moreover, it requires te-
dious operation via a valve or other means to inject the
powder just prior to impressing the discharge power
supply.
We have already developed the idea of using hydrogen
storage alloy working at the temperature of about 100
deg.C which shows successful performance for break-
ing DC arching [Minami et al, 2003].  To fabricate this
type of fuse, however, needs a lot of works and costs not
effective.  This newly designed method to produce hy-
drogen storage Titanium on the surface of the cupper
film seems to be low-cost and needs not much labour.
3.  EXPERIMENTAL RESULT
Figure 1 shows the experimental setup.  When triggered,
the solenoid valve is opened and the acting hydrogen is
injected into the vacuum tube.  Discharging is started
after gas injection using a delayed pulse generator.
The electrodes are coaxial, separated by an insulating
plate and connected to the pulse power supply circuit.
A solenoid valve is attached to the bottom of the insu-
lating plate and injects acting gas between the electrodes.
This swirls the powder up between the electrodes (Fig-
ure 2).
The aforementioned setup starts discharging.  Figure 3
shows the basic configuration of the electrodes in the
vacuum tube and how it operates.  In this experiment,
Titanium powder is used. Before charging the energy
storage capacitor, Titanium powder is placed between
the electrodes of Figure 3, the substrate is positioned a
set distance from the electrodes and a vacuum is drawn.
After a sufficient degree of vacuum is attained, the power
supply capacitor bank (5 kV, 800 µF) can be discharged.
The acting gas is injected by a timing system connected
to the ignitron switch and the Titanium powder swirled
upward as shown in Figure 3.  While the powder is set
between the electrodes, the ignitron tube switch is thrown
to start arc discharge between the electrodes and the
hydrogen is ionized as shown in Figure 4.  Electromag-
netic force, JxB is generated by the magnetic field of
the discharge current, and the plasma is accelerated.  This
electromagnetically accelerated plasma is heated and the
powder is accelerated (Figure 5).  The film is then formed
on the substrate as shown in Figure 6.
Fig. 2  An image of the ignition mechanism of the dis-
charging
Fig. 3  The experimental set up of the experiment
Fig. 4  The mechanism of plasma acceleration due to
JxB force
Fig. 5  The image of the accelerated hydrogen plasma
with the powder
By forming a Hydrogen storage Titanium film on the
copper foil, a high performance fuse of short arc gen-
eration time is made as shown in Figure 7.  The result
shows that a fuse made without hydrogenated Titanium,
whereas Figure 8 shows the fuse without a Titanium film.
Arc breaking time is 50 ms for the fuse of Figure 8, but
it is approximately 1 ms for the fuse shown in Figure 7.
4. DISCUSSION AND CONCLUSION
This newly developed device can accelerate powder elec-
tromagnetically and a thin film of hydrogen coated Tita-
nium on a substrate is made using gas discharge.  When
this thin film is deposited on the surface of a fuse, nega-
tive ions made of Hydrogen discharge that stops main-
taining arcs, hence making a fuse that blows at a high
speed.  In fact, a prototype fuse exhibited a breaking
time of 1 ms.  The production cost of this method seems
to be lower than the previous method using low tem-
perature hydrogen storage metal powder contained in a
cylindrical fuse [Minami et al, 2003].  It is expected that
this fuse will spread on applications with electric ve-
hicles as well as other high voltage power supply.
This result also suggests that even nonconductive pow-
ders can be accelerated by electromagnetic force using
gas plasma discharge and formed as films.  Moreover,
using a hydrogen acting gas, it is possible to hydroge-
nate Titanium powder and deposit on a substrate.  New
material production using this method is expected.
References
Minami S., Y. Kudose, K. Matsumoto, and Y. Takakuwa,
Newly Designed Electric Fuse for High-Power DC
Power Supply , ITE Letters, 6, 256-259, 2003.
Usuba, S., Y. Kakudate, H. Yokoi, S. Fujiwara, J.
Kitamura, and M. Suzuki, Japan Patent 3331375,
2003.
(Received May 21, 2005; accepted June 19, 2005)
Fig. 6  An illustration of the deposited Titanium film
Fig. 7  An example of newly developed fuse character-
istics during the fuse breaking
Fig. 8  An example of non Titan coated fuse characteristics


Development of High Performance DC Fuse for Electric Vehicle and Its Features

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Development of High Performance DC Fuse for Electric Vehicle and Its Features

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