JPH02214162A - Gate turn-off thyristor - Google Patents

Abstract

PURPOSE:To enhance a maximum turn-off current by a method wherein a snubber diode of a snubber circuit is formed to be a ring shape at an outer periphery of a GTO thyristor substrate and a side face of the GTO thyristor substrate and a side face of the snubber diode are formed as positive bevels facing opposite directions. CONSTITUTION:A periphery of a circular gate turn-off(GTO) thyristor substrate composed of a p-emitter layer 1, an n-base layer, a p-base layer 3 and a segment-shaped p-emitter layer 4 is surrounded, via an insulating layer 7, by a ring-shaped snubber diode raw body 30 whose inside and outside have been shaped as positive bevels; a junction direction of a positive-bevel face shaped with reference to the two intermediate (p) and (n) layers 2, 3 is opposite to that of a positive-bevel face of the ring-shaped snubber diode raw body 30 surrounding an outer periphery. As a result, the diode raw body 30 can be approached to a GTO thyristor raw body 10; an inductance of a wiring part is made small. Thereby, a maximum turn-off current can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gate turn-off (GTO) risk including a reverse conduction type integrated diode of a snubber circuit.

[Conventional technology]

When a GTO thyristor is mounted in a converter such as an inverter or a chipper, a snubber circuit is required to reduce the load on the device at turn-off. This snubber circuit for GTO consists of two GTO thyristors, as shown in the equivalent circuit of FIG.
Snubber diode 22 in parallel with 1 and capacitor 23 in series with the diode and snubber diode 22
It consists of a snubber resistor 24 in parallel with
The inductance 25 in FIG. 1, which is designed to avoid the inductance 25, is the equivalent inductance of the entire snubber circuit, and includes the wiring of the snubber circuit, the inductance inside the snubber capacitor 23, etc.

Now, when the GTO thyristor 21 performs turn-off operation,
When the GTO thyristor is turned off, the current flowing through the GTO thyristor is diverted to the snubber circuit and charges the capacitor 23 of the snubber circuit.

At this time, the current flowing into the snubber circuit has a steep current change (
di/dt), so if the size of the inductance 25 included in the snubber circuit is , then a spike voltage of VIP-LmXdi/dt is generated due to the inductance.

Generally, in GTO thyristors, there is a close relationship between the magnitude of this spike voltage ■□ and the maximum turn-off current as shown in Figure 3 with L3 as a parameter. .

That is, for the maximum turn-off current of the GTO thyristor, the equivalent inductance of the snubber circuit is.

It can be seen that the smaller the value, the better.

For the above reasons, many efforts have been made to reduce the inductance of snubber circuits. For example, to reduce the inductance of the wiring, the wiring should be made as short as possible, and a printed bar should be used. , using a capacitor with low internal inductance, and using a snubber diode with low transient on-voltage.

[Problems to be Solved by the Invention] However, even with these methods, it is not possible to prevent an increase in inductance due to the packaging of the snubber diode, the size of the cooling body, and the complexity of wiring for external connection of the snubber diode. First, it was not possible to solve the volumetric problem of the snubber circuit.

An object of the present invention is to eliminate the above-mentioned drawbacks, improve the maximum turn-off current of the GTO thyristor, and provide a GTO thyristor in which a protective snubber circuit can be integrated in a volumetrically compact manner.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a circular GTO thyristor substrate having four pnpn layers, in which an annular snubber diode element body formed with a positive bevel on both the inner and outer sides is surrounded via an insulating layer. The side surfaces of the 912 layer in the middle are positively beveled in the opposite direction with a bevel angle approximately equal to the diode bevel angle.

[Effect]

912 layers in the middle of the GTO Cyrisk board (base layer)
The positive bevel surface formed on the periphery and the positive bevel surface of the annular snubber diode element surrounding the outer periphery are almost parallel because their bonding directions are opposite, so the diode element and the GTO thyristor element should be placed close to each other. The inductance of the wiring between the GTO thyristor and the snubber diode becomes extremely small. In addition, the GTO thyristor substrate and the snubber diode element surrounding it can be placed in one container and heat can be radiated through a common cooling body, and a cooling body for the snubber diode is not required, resulting in a compact design. Therefore, the inductance caused by connection with peripheral circuits is also reduced, and the gap in FIG. 3 is reduced, so that the maximum turn-off current of the GTO thyristor is greatly improved.

〔Example〕

FIG. 1 is a sectional view of a reverse conducting GTO thyristor according to an embodiment of the present invention. The GTO thyristor section 10 includes a p emitter layer 1+ an n base layer 2. Consisting of a p base layer 3 and a segmented p emitter layer 4, an n base layer 2 is formed around it.
A freewheeling diode section 20 consisting of an extension of the p-base layer 2 and an extension of the p-base layer 2 is present with a separation strip 40 interposed therebetween. The freewheeling diode is molded with a positive bevel, and is surrounded by a snubber diode section 30 consisting of a p layer 5 and an n layer 6 stacked in the opposite direction to the freewheeling diode. The snubber diode has positive bevel molding on both the inside and outside surfaces, and the beveled surface of the freewheeling diode and the beveled surface of the snubber diode are parallel, and the space between them is filled with a pansy base insulator 7 such as silicone rubber. ing.

Such a passive bass insulator 7 also covers the outer bevel surface of the snubber diode. GTO thyristor section 10. The freewheeling diode section 20 and the snubber diode section 30 are composed of a Mo plate 8 that also serves as the anode electrode of the GTO thyristor, the cathode electrode of the freewheeling diode, and the anode electrode of the snubber diode.
is fixed on top. And in the p base layer 3, GTO
The gate electrode 91 of the thyristor and the anode electrode 93 of the freewheeling diode are connected to the GTO layer in the n emitter layer.
A cathode electrode 9z of the thyristor and a cathode electrode 94 made of M are in contact with the O layer 6 of the snubber diode. Each bevel surface is formed by sandblasting and etching to have the same bevel angle.

Figure 4 is a top view of the element shown in Figure 1, with GT
O thyristor part 10. Separation strip 40. The freewheeling diode section 20 and the snubber diode section 30 are arranged in this order, and between the freewheeling diode section 20 and the snubber diode section 30 there is a bevel surface that is positive for both the freewheeling diode and the snubber diode. A positive bevel surface is formed on the outside of the snubber diode section 30, and both are covered with an insulator 7.

FIG. 5 is a sectional view of the reverse conduction GTO thyristor with a built-in snubber diode according to the present invention housed in a pressurized contact type container. In this container structure, GTO thyristor 10
The Mo plates fixed to the anode of the freewheeling diode 20, the cathode of the freewheeling diode 20, and the anode of the snubber diode 30 are integrally in contact with the copper electrode body 11. On the other hand, the cathode electrode 92 of the GTO thyristor 10 is pressed into contact with the freewheeling upper copper electrode body 13, but the gate lead 14 is connected to the gate electrode 91 of the GTO thyristor 10, and the annular cathode electrode of the snubber diode 30 94 is the GTO thyristor section 10. It maintains insulation from the freewheeling diode section 20 and is brought into pressure contact with the annular surface of the terminal 15 of the snubber diode, and the L terminal 15 is connected to the snubber capacitor and the snubber resistor, and the second
The circuit shown in the figure was formed.

In the above embodiment, a reverse conduction GTO thyristor was described, but a normal GTO thyristor without a freewheeling diode section
A similar implementation is possible for TO thyristors. In that case, GTO
The sides of the thyristor are positively beveled to the junction between the p and n base layers.

〔Effect of the invention〕

According to the present invention, the snubber diode of the snubber circuit provided for reducing the duty at turn-off of the GTO thyristor is formed in an annular shape around the outer periphery of the GTO thyristor substrate, and
The side surface of the O thyristor substrate and the side surface of the snubber diode are made with opposite positive bevels to narrow the gap between them, so that they can be easily accommodated in one container, and the inductance of the wiring between them is reduced. In addition, the GTO thyristor board and snubber diode element, both of which have increased withstand voltage through bevel molding, are compactly assembled, and the inductance of external connection wiring with other snubber circuit components is also reduced, thereby reducing reverse conduction. It is possible to improve the maximum turn-off current of the GTO thyristor, including its shape.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main parts of a snubber diode composite reverse conduction GTO thyristor according to an embodiment of the present invention, Fig. 2 is a circuit diagram of the GTO thyristor and snubber circuit, and Fig. 3 is a GTO thyristor with the snubber circuit equivalent inductance as a parameter. Relationship diagram between thyristor maximum turn-off current and spike voltage, Figure 4 is a top view of the composite element shown in Figure 1, and Figure 5 is a cross-sectional view of the composite element shown in Figure 1 housed in a container. It is. to: c'ro thyristor section, 20: freewheeling diode section, 30: snubber diode section, l: p emitter layer, 2: n base layer, 3: p base layer, 4: n emitter layer. Figure 1 Turn-off electric 2nu ITGOM (A) 3rd
Figure 2 Figure 4

Claims (1)

[Claims] 1) A circular GTO thyristor substrate having four pnpn layers is surrounded by an annular snubber diode body with positive bevel molding on both the inside and outside sides via an insulating layer, and the GT
A gate turn-off thyristor characterized in that the side surface of the O thyristor substrate is positively beveled in the opposite direction to the intermediate pn2 layer with a bevel angle substantially equal to the diode bevel angle.