JP2736069B2 - Semiconductor switching circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor switching circuit that switches a circuit charged to a high voltage by a semiconductor switching element to obtain a high-speed, large-current pulse current.

(Prior Art) A conventional technique will be described with reference to the drawings. In recent years, industrial demand for so-called pulse power technology for exciting a gas laser using a pulsed large current or forming a pulse magnetic field has been increasing. As a method of obtaining a large pulse current, a method of switching a circuit such as a capacitor charged to a high voltage is generally used, and a thyratron or a gas gap filled with a low-pressure hydrogen gas or the like is often used as a switching element. Was. However, thyratrons, gas gaps, and the like have a drawback that the switching involves a discharge, so that the electrodes cannot be prevented from being consumed, and the life of the element is short. In order to solve this drawback, recently, an attempt has been made to perform necessary switching by using a semiconductor element.

FIG. 4 is a configuration diagram of a conventional semiconductor switching circuit. The plurality of semiconductor switching elements S ₁ to S _n radiator R ₁ ~R _{n + 1}
Sandwiched alternately between the top connected in series radiator from R ₁ the bottom of the radiator in towards the plurality of return conductor 10 is one collectively in the lower part of the disposed in a cylindrical shape so as surrounding the entire apparatus As the cathode terminal K, it is juxtaposed with the anode terminal A taken out from the lowermost radiator Rn _{+ 1} .

In addition, a snubber circuit 20 including a capacitor, a diode, and the like is connected in parallel with the switch element between adjacent radiators to suppress an overvoltage generated at the time of switching.

In the conventional semiconductor switch circuit configured in this way, since the elements are connected in series, the withstand voltage can be increased as a whole even if a semiconductor element with a withstand voltage of about several kV is used, and the element and the return circuit are coaxial. , The inductance of the circuit can be reduced, and as a result, a high-speed, large-current pulse current is obtained.

(Problems to be Solved by the Invention) However, the conventional semiconductor switching circuit has the following disadvantages. This will be described with reference to the drawings.
FIG. 5 is a plan view of a switch element portion of the conventional semiconductor switching circuit shown in FIG.
Is a return conductor. However, for the sake of simplicity, the snubber circuit is omitted, and the return circuit is shown as being uniformly spread in a cylindrical shape. By the way, in the case of such a concentric configuration, the current flowing through the inner switch element is not uniform. That is, at a high frequency, the current flows intensively to the outside due to the skin effect. In FIG. 5, the slanted lines represent regions where current flows.

Since the current flows in a concentrated manner in a part, the conduction loss of the element increases. Therefore, the size of the radiator becomes large, and the element itself must have a large capacity. As a result, the size of the switching circuit must be increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the conventional semiconductor switching circuit, and has as its object to obtain a small, low-loss, high-speed semiconductor switching circuit.

(Means for Solving the Problems) In a semiconductor switching circuit in which a plurality of semiconductor switching elements are connected in series and a high-speed large-current pulse current is obtained by switching a circuit charged to a high voltage, a series connection is made. The semiconductor switching element of each stage is constituted by a plurality of semiconductor elements connected in parallel, a plurality of semiconductor elements connected in parallel are arranged in a circle, and a plurality of semiconductor elements connected in series as a whole are arranged in a cylindrical shape,
Further, a return circuit composed of a coaxial cylindrical conductor is provided outside the plurality of semiconductor elements arranged in the cylindrical shape, and a return circuit composed of the coaxial cylindrical conductor adjacent to one end of the plurality of semiconductor elements connected in series is provided. The other end of the plurality of semiconductor elements connected in series is connected to one end of the circuit, and the other end of the return circuit including the coaxial cylindrical conductor is set as the other terminal.

(Operation) Since the current is uniformly distributed to the plurality of semiconductor switching elements connected in parallel and arranged in a circle, the loss of the switching circuit can be reduced. Further, the circuit inductance is reduced by the return circuit, and a large current can flow at a large current change rate.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. First
1 is a side view of a semiconductor switching circuit according to the present invention, and FIG. 2 is a plan view. The plurality of semiconductor switches S are connected in series alternately with the radiator R, and are also formed by connecting a plurality of elements in parallel in each stage connected in series. The arrangement of the multi-stage elements connected in parallel is circumferential as shown in FIG. The concentric cylindrical return conductor 10 is further provided so as to surround the switching element formed in a cylindrical shape as a whole as described above. Also snubber circuit 20
Are wired at equal distances to the switching elements provided in the center and connected in parallel through the radial conductor 11.

In the semiconductor switching circuit of the present invention thus configured, since the switching element S and the return circuit 10 form a coaxial cylinder, not only the circuit inductance is small and high-speed high-current switching is possible, but also the switching element is Since they are arranged on the circumference, the current flows almost uniformly over the entire surface of the element as shown by the hatched portion in FIG. 2 also by the skin effect.

As a result, the conduction loss does not increase unnecessarily, so that the radiator can be reduced in size, and a low-loss, high-speed semiconductor switching circuit can be obtained.

Further, since the snubber circuits are wired at equal distances to all elements, one set of snubber circuits is sufficient for all elements connected in parallel.

FIG. 3 is a block diagram of another embodiment of the present invention. In this embodiment, the return circuit 10 also serves as a storage tank for the switching circuit. The switching circuit is immersed in the liquid refrigerant 30 and housed therein, and the switching circuit is cooled by circulating the refrigerant through inlets and outlets provided at upper and lower portions. The lower end of the switching element is connected to the return circuit at the bottom,
According to this method in which the upper end is drawn out of the tank through the insulating through insulator 40, cooling can be efficiently performed not only from the radiator but also from the surface of the switching element itself, so that the cooling efficiency is improved and the size can be reduced.

In addition, if a material having excellent insulation properties such as insulating oil is used as the cooling medium, the insulation distance can be reduced, so that the size can be further reduced.

In the present invention, the cylindrical return circuit does not necessarily mean a completely closed circular cylinder. If the resulting electromagnetic field is not extremely distorted, an independent conductor may be arranged in a circle.

(Effects of the Invention) According to the semiconductor switching circuit of the present invention, the current flowing through each semiconductor element is well balanced, the size can be reduced with low loss, and the inductance can be reduced by the return circuit. Energization can be performed at a current change rate.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a side view, FIG. 2 is a plan view, FIG. 3 shows another embodiment of the present invention, and FIG. FIG. 5 is a configuration diagram of a conventional circuit, and FIG. 5 is a diagram showing a current distribution of the circuit of FIG. S, S _{1 to} Sn _n switching elements R, R _{1 to} R _{n + 1} radiators, A… anodes K… cathodes, 10… return circuits 20… snubber circuits, 30… refrigerant 40 ...... Insulated through insulator

Claims (2)

(57) [Claims] 1. A semiconductor switching circuit in which a plurality of semiconductor switching elements are connected in series to switch a circuit charged to a high voltage to obtain a high-speed, large-current pulse current. The switching element is composed of a plurality of semiconductor elements connected in parallel, the plurality of semiconductor elements connected in parallel are arranged in a circle, and the plurality of semiconductor elements connected in series as a whole are arranged in a cylindrical shape. A return circuit consisting of a coaxial cylindrical conductor is provided outside of the plurality of semiconductor elements arranged in, and one end of the plurality of semiconductor elements connected in series is connected to one end of a return circuit consisting of the adjacent coaxial cylindrical conductor. The other end of the plurality of semiconductor elements connected in series becomes one terminal, and the return circuit comprising the coaxial cylindrical conductor Semiconductor switching circuit and the other end of the other terminal. 2. The method according to claim 1, wherein the return circuit comprises a tank made of a confidential cylindrical conductor having an insulating refrigerant sealed therein, and circulates the insulating refrigerant to cool the plurality of semiconductor elements. 2. The semiconductor switching circuit according to claim 1, wherein: