JPS6336205B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention applies to thyristors, transistors, GTO
Semiconductor devices composed of semiconductors such as thyristors,
In particular, the present invention relates to a semiconductor device with an improved snubber circuit connected in parallel with a semiconductor.

It is well known that when the maximum rated voltage of a semiconductor is equal to or smaller than the circuit voltage, a plurality of semiconductors are connected in series. When a plurality of semiconductor elements are connected in series, a snubber circuit is connected in parallel to the semiconductors in order to balance voltage sharing within an allowable range.

In addition, in semiconductors that perform high-speed switching operations, an abnormal surge voltage occurs across the semiconductor when the current is turned off, and if the maximum rated voltage of the semiconductor is exceeded, the semiconductor will be destroyed. A snubber circuit is also provided in parallel to the semiconductor.

FIG. 1 shows a conventional semiconductor device.
In the figure, two semiconductors, namely diodes 1
and 2 are connected in series, and resistors 3,
A snubber circuit consisting of 4, 5 and 6 and capacitors 7 and 8 is shown connected in parallel with diodes 1 and 2. Resistors 3 and 4 are provided for the purpose of voltage sharing during steady state, and resistors 5 and 6 and capacitors 7 and 8 are provided for the purpose of voltage sharing during transient times and surge voltage suppression.

In particular, it is necessary to minimize the inductance of the series circuit of capacitor 7 (or 8) and resistor 5 (or 6) connected to both the anode and cathode electrodes of diode 1 (or 2) in order to suppress surge voltage. Therefore, consideration is given to reducing the inductance by using resistor and capacitor parts that have a non-inductive structure, and by arranging the resistor and capacitor parts near the semiconductor and shortening the wiring. There is.

Furthermore, in order to reduce the wiring inductance, as shown in FIG. 2, electric wires wired at both ends of each component are twisted together to reduce the wiring inductance.

However, there is a limit to how snubber circuit components consisting of the resistors and capacitors described above can be installed near semiconductors, and even if the wires are twisted together as shown in Figure 2, it is difficult to install them in the vicinity of the semiconductor. There have been many cases in which the wiring inductance cannot be reduced to a predetermined value or less because the proportion of matched components is small.

FIGS. 3 and 4 are for explaining the above drawbacks in more detail, and show a semiconductor unit in which a semiconductor and a snubber component are assembled on a single insulating plate 10. A stack 1 is formed by stacking semiconductors 1 and 2 and cooling fins 12 on one side of the insulating plate 10 and assembling them using a tightening device (not shown).
1 and resistors 5, 6, 3 and 4 are shown attached, and capacitors 7 and 8 are shown attached to the other side of the insulating plate 10. Each of resistors 5 and 6 is composed of two resistors connected in parallel.

The wiring of the snubber circuit consists of a conductor 13a that is wired from a terminal 12a provided on the anode side fin of the semiconductor 1 through the insulating plate 10 to one terminal of the capacitor 7, and a conductive wire 13a that is wired from the other terminal of the capacitor 7 to the insulating plate 1.
0 and wires 13b and 13d to connect the two resistors 5 in parallel, the other terminal of the resistor 5 and the cathode side fin of the semiconductor 1. Terminal 1 provided in
The conductor 13e connects the conductor 2b. The snubber circuit of semiconductor 2 is also connected in the same way. Wiring for resistors 3 and 4 is not shown.

As can be seen from FIGS. 3 and 4, in the configuration of such a semiconductor unit, semiconductor 1 or 2
It is difficult to twist or twist the wiring between the resistor 5 or 6 for the snubber circuit, and the capacitor 7 or 8 as shown in FIG. Third
Although the wirings 13e and 13a are twisted in the figures and FIG. 4, the twisted range is small compared to the total wiring length and the effect of reducing wiring inductance is extremely small. In the freewheeling diode snubber circuit used in the chopper device of electric cars, when the capacitance of capacitors 7 and 8 is 1 μF, two resistors with a rated power of 300 W are used in parallel as resistor 5 or 6. The size of this single resistor is the diameter
If the length is 40mm and the length is 450mm, and you try to twist the conductor connected to both terminals of the resistor, the wiring will become longer and the wiring inductance will increase.

The semiconductor units in Figures 3 and 4 show the case where the semiconductor, snubber resistor, and capacitor are installed as close as possible, but there are various forms depending on the configuration of the semiconductor device and the cooling method. When semiconductors are cooled using the boiling cooling method, where the semiconductor is stored in a cooling tank and the resistors and capacitors are installed outside the cooling tank, the semiconductor and resistors and capacitors cannot be placed close to each other. Therefore, the snubber circuit becomes longer, the wiring inductance increases, and the surge absorption effect decreases. For this reason, the capacitance of the capacitor increases and improves the surge absorption effect, but when the capacitance of the capacitor increases, the amount of heat generated by the resistor also increases in proportion to the capacitance, and the efficiency of the semiconductor device decreases. There was a tendency for equipment to become larger.

The present invention has been made in order to improve the drawbacks of the above-mentioned conventional devices, and provides a semiconductor device that effectively suppresses the wiring inductance of a snubber circuit and increases the surge absorption effect.

FIG. 5 shows an embodiment of the snubber circuit wiring method of the present invention. In Figure 5, resistor 3
The steady-state snubber circuit consisting of 4 and 4 is the same as the conventional one, but the capacitor 7 (or 8) and resistor 5 are particularly problematic due to wiring inductance.
(or 6) shows a novel connection that is effective for reducing wiring inductance regarding a series-connected snubber circuit for transient use.

A capacitor 7 forming the snubber circuit of the semiconductor 1 and a capacitor 8 forming the snubber circuit of the semiconductor 2 are arranged adjacent to each other, and similarly the resistors 5 and 6 are arranged adjacent to each other. It is shown. Capacitor 7 and Capacitor 8
The terminal on the same side of one of the resistors 5 and the terminal on the same side of one of the resistors 6 are connected to the conductor 14a, respectively.
and 14b. The other terminals of capacitors 7 and 8 are also connected to conductive wires 14c to the anode terminal of semiconductor 1 and the cathode terminal of semiconductor 2, respectively.
and 14d for wiring. The other ends of resistors 5 and 6 are wired to the connection point between semiconductor 1 and semiconductor 2 by conducting wires 14e and 14f, respectively. capacitor 7
and 8 and resistors 5 and 6 are arranged close to each other, so that the conductive wires 14a, 14b, 14c
and 14d, and 14e and 14f can be wired close to each other, and can also be easily twisted or twisted as shown in FIG. Therefore, the ratio of the twist range to the total wiring length can be increased.

Now, if the potential on the cathode side of the semiconductor 2 where the surge voltage has occurred is higher than the potential on the anode side of the semiconductor 1, the current in the snubber circuit of the semiconductor 1 will flow from the cathode of the semiconductor 1 to the resistor 5 to the capacitor 7 to the semiconductor 1. Flows towards the anode. On the other hand, the current in the snubber circuit of the semiconductor 2 flows in the direction of the cathode of the semiconductor 2, the capacitor 8, the resistor 6, and the anode of the semiconductor 2. In this way, the wirings 14d and 14c,
Since currents flow in opposite directions to 14a and 14b, and 14e and 14f, by twisting these wires, the magnetic flux generated around the conductor wires due to the current flow can be canceled out, and the self-inductance of the wiring can be reduced. can.

When an abnormal voltage occurs in the series circuit of semiconductor 1 and semiconductor 2, the abnormal voltage is not necessarily shared equally between semiconductor 1 and semiconductor 2 due to the characteristics of semiconductor 1 and semiconductor 2, and the current flowing through each snubber circuit is also the same. This causes a certain amount of imbalance rather than the current value. However, the current imbalance in this snubber circuit is about 10%, so simply twisting the wiring of different snubber circuits can sufficiently reduce inductance.

Figure 6 shows a case in which only one wire is used between resistors 5 and 6 and the connection line between semiconductor 1 and semiconductor 2. The same effect as in Figure 5 can be obtained, and the manufacturing cost is reduced because there are fewer wires. You can also plan.

FIG. 7 is a circuit diagram showing the wiring method of the present invention shown in FIGS. 5 and 6. Compared to the conventional circuit shown in FIG. 1, only the resistor 6 and capacitor 8 are replaced. In terms of performance, they show exactly the same circuit.

FIG. 8 is a diagram showing another embodiment of the present invention, in which two semiconductors are connected in parallel.
As shown in this figure, semiconductor 20 and semiconductor 21 are connected in parallel via reactors 22 and 23 in order to make the current sharing as equal as possible. The snubber circuit for semiconductor 20 is capacitor 2
4 and a resistor 26, and the snubber circuit of the semiconductor 21 is composed of a capacitor 25 and a resistor 27. Capacitors 24 and 25 and resistors 26 and 27 are arranged close to each other, and the wiring of each snubber circuit is also arranged close to each other or twisted. As shown in FIG. 8, the wiring of the snubber circuit of the semiconductor 20 and the wiring of the snubber circuit of the semiconductor 21 are connected to the semiconductors 20 and 21 so that the current directions are opposite to each other. Therefore, even when semiconductors are connected in parallel, the same effects as in the case of series connection shown in FIGS. 5 and 6 can be obtained.

As described above, according to the present invention, semiconductors are connected in parallel or in series, the wiring of each snubber circuit is twisted or close to each other, and the directions of current flowing through the wiring of each snubber circuit are opposite to each other. By arranging the wires in the same direction, the wiring inductance of the snubber circuit is reduced and the surge voltage applied to the semiconductor is effectively suppressed. Therefore, when the surge voltages are about the same, it is possible to reduce the component ratings of the snubber circuit, and a compact, lightweight, and highly efficient semiconductor device can be obtained.

In particular, the present invention has a simple configuration but has great effects and is highly practical.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing the configuration of a conventional semiconductor and a snubber circuit, Figure 2 is a diagram showing a wiring method for suppressing the wiring inductance of a conventional snubber circuit, and Figure 3 is a diagram showing a conventional semiconductor device. Figure, 4th
The figure is a left side view of FIG. 3, FIGS. 5, 6, and 7 are connection diagrams showing snubber circuit wiring according to one embodiment of the present invention, and FIG. 8 is a diagram according to another embodiment of the present invention. FIG. 3 is a connection diagram showing snubber circuit wiring. In the figure, 1 and 2 are diodes (semiconductor),
5 and 6 are resistors, 7 and 8 are capacitors,
14a to 14f are wirings, 20 and 21 are semiconductors, 22 and 23 are reactors, 24 and 2
5 is a capacitor, and 26 and 27 are resistors.

Claims (1)

[Scope of Claims] 1. In a semiconductor device configured by connecting a snubber circuit in parallel to each of a plurality of semiconductors connected in parallel or in series, the components constituting each of the snubber circuits are arranged close to each other, and the 1. A semiconductor device characterized in that currents flowing through the wires of each snubber circuit are arranged in opposite directions, and the wires are twisted close to each other. 2. The semiconductor device according to claim 1, wherein each snubber circuit is formed of a series connection of a capacitor and a resistor.