JP2677697B2 - Module element - Google Patents

Description

The present invention relates to a power semiconductor control element, and more particularly to a module element having improved explosion-proof characteristics.

(Prior Art) As shown in FIG. 3, a power semiconductor control element includes a bipolar transistor, a MOSFET, and an IGBT (Iisulated Gate Bipolar Transistor) as switching elements 61 to 66 of an inverter bridge 4.
ransistor) various things are used.

FIG. 3 is a general configuration example of a transistor inverter for driving an AC motor.

In FIG. 3, a power supply composed of a DC power supply 1 and a filter capacitor 2 is supplied to a transistor bridge 4 via a high-speed fuse 3, and its AC output causes the motor 5 to move.
Is driven.

The transistor bridge 4 includes transistors 61, 62, 63, 6
It forms a three-phase inverter bridge consisting of 4,65,66.

The transistors currently used for this are mainly of modular type, the main electrode and the cooling surface are electrically insulated, and the main electrode is connected to the transistor chip via a bonding wire.

Fig. 4 shows an example of the structure of a module type transistor. An insulating ceramics 81 with good thermal conductivity is adhered on a copper base 80 that radiates heat to a cooling fin, and copper materials 82, 83, 84 are placed on it. The collector of the transistor pellet 85 is bonded to the copper material 82 with the emitter terminal facing upward, the emitter terminal is bonded to the emitter electrode 89 with a bonding wire 87, and the collector side is bonded to the collector electrode 88 with a bonding wire 86. It is connected.

In fact, in addition to this, the base signal terminal is also connected, and as shown in Fig. 5, the emitter E and collector are connected outside the module.
The terminals of C and base B are pulled out, and the outer wall is covered with an insulating molding material.

In the inverter circuit configured as a bridge as shown in Fig. 3, if one of the upper and lower transistors blows out, the DC power supply is short-circuited and an overcurrent flows through the transistor. An overcurrent protection circuit (not shown) detects this and turns off all the transistors. By doing so, overcurrent protection is provided. But,
If the DC voltage is high or the control circuit is abnormal, protection cannot be performed within the safe operating area of the transistor, the other transistor will also puncture and the short-circuit current will increase, the bonding wire will melt and an arc will occur, and the module type transistor Since the outer wall is scattered and dangerous, the fault current is cut off by the high-speed fuse 3.

When the capacity of the inverter becomes large, it is necessary to use a large number of module elements in parallel. In this case, in order to prevent the outer wall of the module element from bursting, connect a high-speed fuse to the collector side of each transistor module as shown in FIG. doing. This is because, assuming the common fuse 3 on the DC side as shown in FIG. 3, there is no fuse that is suitable for protection of all module elements connected in parallel.

Further, in FIG. 6, a fuse is inserted in the collector side of each transistor, but since the base driving signal of the transistor is applied as a common reference potential to the emitter side of each transistor, there is no potential fluctuation on the emitter side. It is necessary to do so.

FIG. 6 shows one phase of a transistor bridge. The emitters and bases of a plurality of transistors 61-1 to 61-n are connected in parallel, and high-speed fuses 31-1 to 31-are connected to the respective transistors. n is inserted.

Similarly, the bases and emitters of the transistors 62-1 to 62-n are connected in parallel, and the high-speed fuses 32-1 to 32-n are inserted in the respective transistors.

Further, the capacitor 8 is arranged as close as possible to the element in order to absorb the surge of the DC bus.

(Problems to be Solved by the Invention) However, when a fuse is connected to the collector side of each transistor as shown in FIG. 6, the wiring length for that is increased and the inductance L is increased, so that the surge voltage (L There is a problem that the di / dt) becomes high and the reliability of the device is lowered.

In particular, recently developed IGBTs and MCTs (MOS Controlled
Thyristor) has a switching speed several times faster than bipolar transistors, so di / dt is several times faster (5 to 5 times).
6 times higher), and the surge voltage rises accordingly, and the conventional circuit system cannot be used.

Therefore, a surge voltage absorbing circuit as shown in FIG. 7 has been used.

That is, when the wiring inductances La, Lb, Lc, Ld exist in the main circuits of the respective IGBTs 71, 72, the capacitor 9
And the diode 10 clamp the surge energy between the collector and the emitter of the IGBT71 and discharge it to the capacitor 2 via the resistor 16 and also the diode 72 for the IGBT72.
1. The surge energy is discharged by the capacitor 12 to the capacitor 2 through the clamp resistor 15.

However, this circuit has drawbacks such as the number of components used becomes complicated, it is necessary to provide a surge clamp circuit for each element, and energy loss occurs in the resistors 15 and 16, resulting in reduced efficiency. There is.

Since the present invention suppresses the increase in inductance due to the insertion of the high speed fuse, the high speed fuse is omitted,
The purpose of interrupting the fault current by a high-speed fuse is to provide a module element for a transistor bridge, which is economical and generates less surge voltage, by utilizing melting of a bonding wire of the module element.

[Configuration of the invention]

(Means for Solving the Invention) The present invention relates to a semiconductor pellet housed in a hermetically sealed container and a power semiconductor control element equipped with an electrode terminal led out of the container. Electrode terminals are connected by wire bonding, and the container is reinforced and an arc extinguishing agent is filled therein to form a module element.

(Function) When an overcurrent flows through the module element, the connecting portion of the bonding wire is blown to generate an arc, but the arc quenching agent cools the arc and extinguishes the accident current. Further, since the bursting of the module element can be prevented, the high-speed fuse for preventing the bursting can be omitted, the inductance component due to the high-speed fuse wiring of the inverter bridge is reduced, and the surge voltage is remarkably reduced.

(Example) FIG. 1 shows an example of a module element according to the present invention. FIG. 1 is a block diagram of the module element, and the same parts as in FIG.

The collector C of the transistor pellet 85 is adhered to the copper material 82, and the copper material 82 is bonded to the collector electrode 88 by the bonding wire 86 and output as the collector terminal 92. The emitter E of the transistor pellet 85 is connected to the emitter electrode 89 by the bonding wire 87 and is output as the emitter terminal 93.

Base B (or gate) of transistor pellet 85
Is connected to the gate electrode 90 by a bonding wire 91 and is output as a gate terminal 94.

The module element is covered with a case including a side cover 95 and a top cover 96, and an arc extinguishing agent 97 is filled inside.

Since the bonding point A is connected to the copper material 82, the cooling effect is good, but the bonding point B is connected to the emitter E of the transistor pellet 85, so the cooling effect is poor and the transistor part is deteriorated. When excessive loss occurs, the fusing always occurs near point B. When fusing occurs at point B and an arc is generated, the arc is extinguished by the arc extinguishing agent 97 around the arc, and the accident current is interrupted. At this time, the internal gas pressure rises, so the case is reinforced so as not to burst.

FIG. 2 shows an example of reinforcing the case of the module element. In a normal case, the side cover may swell and burst due to gas pressure. Therefore, as shown in FIG.
95 is partially provided with a convex portion d to reinforce, and at the same time, protrusions e and f are provided on the upper and lower portions to fit in the upper and lower cases,
Prevent side cover swelling.

Further, in order to prevent the side cover from scattering due to bursting, it is also possible to protect the surrounding area with a rubber cover 98.

Further, in order to increase the strength of the side cover, a mixed material of fibers (glass fiber etc.) can be used.

〔The invention's effect〕

As described above, according to the present invention, the fact that the bonding portion of the transistor / emitter located in the center of the module element is melted first is used to fill the periphery and extinguish the arc with the arc-extinguishing agent. Then, the accident current is cut off, and the rupture due to the gas pressure generated in this process can be prevented by reinforcing the case. As a result, the conventionally used high-speed fuse can be omitted, and an economical and compact inverter bridge can be constructed. In addition, since the inductance associated with the fuse wiring is reduced, the surge voltage (energy) at the time of switching is reduced, which makes it possible to omit or downsize the surge absorption circuit, resulting in high efficiency and at the same time reducing the surge voltage to ensure a safe operating area for the switching element. With respect to the above, it is possible to provide a module element in which a margin is increased and a highly reliable inverter bridge can be configured.

[Brief description of the drawings]

FIG. 1 is an embodiment diagram of the present invention, FIG. 2 is a partial embodiment diagram of the present invention, and FIGS. 3, 6, and 7 are configuration diagrams of an inverter bridge using a conventional module element. FIG. 5 and FIG. 5 are configuration diagrams of a general module element, and FIG. 8 is an embodiment diagram of an inverter bridge using the module element according to the present invention. 1 ... DC power supply, 2,8,12 ... capacitor 3,31,32 ... fuse 4 ... transistor bridge, 5 ... motor 15 ... resistor 71,72 ... module element according to the present invention 80 ... copper Base, 81 …… Insulating ceramics 82,83,84,88,89 …… Copper material 86,87,91 …… Bonding wire 95,96 …… Cover, 97 …… Arc extinguishing agent 92,93,94 …… Terminal

Claims (1)

(57) [Claims] 1. A power semiconductor control device comprising a semiconductor pellet housed in a sealed container and an electrode terminal led out of the container, wherein the semiconductor pellet and the electrode terminal are connected by wire bonding. In addition, the module element is characterized in that the arc-quenching agent is filled in the container.