JPS61185064A - Drive circuit of static induction type self-extinguishing element - Google Patents

Abstract

PURPOSE:To prevent a static induction type self-extinguishing element from deteriorating by providing a voltage regulator for regulating a gate voltage in response to the collector voltage of the element. CONSTITUTION:A voltage of a gate power source 4 is applied to the gate of a static induction self-extinguishing element 3 through transistors 6, 7 complimentarily connected with a base common connecting point through a resistor 10 with a drive signal Vs. The collector of an NPN transistor 14 is connected with the base common connecting point of the transistors 6, 7, the emitter of the transistor 14 is connected through a resistor 13 with the negative electrode of the power source 4, and the base is connected through a resistor 11 with the collector of the element 3. The gate voltage of the element 3 is regulated in response to the collector voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a drive circuit that safely drives an electrostatic induction type self-extinguishing element, and is particularly used in a power supply device.

[Technical background of the invention]

2. Description of the Related Art Devices using electrostatic induction type self-extinguishing elements are known as DC-AC or DC-AC power exchange devices. This electrostatic induction type self-extinguishing element is GE's IGT.
(In5ula-ted Gate Transist
or ) is known, for example “＾pplicati
on of In5ufated Gate Tra
nsis-tors” (Fa member 0ryElfliC
trOnics 1983). Typical GE product number 094FQ described in the document
1 (18A, 400V) and FRI (18A, 400V).

500V) Gate voltage GE' Collector voltage V
According to Figure 8, which shows the correlation of the CE1 collector current IC, in the range where the gate voltage VGE is low, the transistor exhibits constant current characteristics similar to that of a transistor, but as the gate voltage VGE increases, it exhibits a low voltage drop similar to that of a thyristor. It can be seen that it has characteristics intermediate to that of a thyristor.

Moreover, FIG. 9 shows the safe operating area (SOA) of the electrostatic induction type self-extinguishing element shown in FIG. 8. For example, if the gate-emitter resistance R6E is 5Ω,
This shows that safe operation is always possible if the collector current is limited to the following.

However, if you try to turn off a current higher than the rated maximum current, so-called latch-up will occur, and the gate voltage VG
Even if E is set to 0, the collector current IC cannot be set to 0, and the current density within the device increases, causing deterioration of the device. Therefore, when driving the electrostatic induction type self-extinguishing element, it is necessary to avoid using it beyond the safe operating range.

FIG. 10 shows a gate drive circuit for a conventional electrostatic induction type self-extinguishing element. According to this, the collector of the electrostatic induction type self-extinguishing element 3 is connected to the positive electrode of the DC power supply 1 via the load 2, the emitter is connected to the negative electrode, and the DC power supply 1 and the negative electrode are connected in common to each other. The positive terminal of the power supply 4 is connected to the collector of an NPN transistor 6 via a resistor 5. NPN transistor 6 and PN for amplification
It is complementary connected to the P transistor 7, and the drive signal VS is input to the base common connection point.
A gate of an electrostatic induction type self-extinguishing element 3 is connected to a common connection point of the emitters of the transistors 6 and 7 via a resistor 8 and a diode 9 connected in parallel.

In this circuit, when the drive signal VS is turned on, the voltage of the power supply 4 is applied to the transistor 6 and the diode 9.
When the drive signal Vs is turned off, the gate is applied to the emitter of the electrostatic induction self-turning element 3 through the resistor 8 and the transistor 7. It is short-circuited and the gate potential drops. At this time, the resistor 8 is R6 in FIG. The maximum collector current may be limited depending on the magnitude of this resistance value.

[Problems with background technology]

However, in such a drive circuit, the gate voltage of the electrostatic induction type self-extinguishing element is determined by the gate N source 4 with a fixed potential, so there is little variation, and the characteristics of the electrostatic induction type self-extinguishing element cannot be effectively exhibited. There is a problem.

That is, in the circuit of FIG. 10, ■. If E=20V, the voltage drop will be low, but if an accident occurs on the load side, the collector current will exceed 100A, which is outside the safe operating area shown in FIG. 9, and the element will deteriorate. Also,
In order to always keep the maximum collector current below 20A to prevent element deterioration, it is necessary to limit ■GE to 8■ from Figure 8, but when the electrostatic induction type self-extinguishing element is turned on. If the collector current at that time is 10A, the voltage drop between the gate and collector is 30% compared to when VQE is -20V.
%, and at a collector voltage of 15 A, it becomes about five times as large, resulting in a significant increase in loss.

[Purpose of the invention]

The present invention was made to solve these problems, and it is an object of the present invention to provide a drive circuit for an electrostatic induction type self-extinguishing element that can maintain the maximum collector current within a safe operating area and reduce loss. With the goal.

[Summary of the invention]

In order to achieve the above object, the present invention detects the collector voltage of the electrostatic induction type self-extinguishing element, and provides a voltage that lowers the gate voltage of the electrostatic induction type self-extinguishing element according to the detected voltage. Equipped with an adjustment circuit, it is possible to prevent element deterioration.

[Embodiments of the invention]

Some embodiments of the present invention will be described in detail below with reference to the drawings. Note that the same components as in the prior art will be given the same numbers and detailed explanations thereof will be omitted.

FIG. 1 is a circuit diagram showing an embodiment of a drive circuit for an electrostatic induction type self-extinguishing element according to the present invention, and as in the case of FIG. 10, the voltage of the gate m source 4 is The signal VS is applied to the gate of the static R-inductive self-extinguishing element 3 through complementary connected transistors 6 and 7, which are applied to the base common connection point through a resistor 10, but the transistors 6 and 7 NP is at the base common connection point of
The collector of an N-type transistor 14 is connected, the emitter of this transistor 14 is connected to the negative electrode of the gate power supply via a resistor 13, and the base is connected to the collector of the electrostatic induction type self-extinguishing element 3 via a resistor 11. has been done. Furthermore, a Zener diode 15 and a resistor 12 are connected in parallel between this base and the negative electrode of the gate power source 4.

Next, the operation of this circuit will be explained with reference to FIGS. 2 and 3.

Resistors 11 and 12 are collector voltages of electrostatic induction type self-extinguishing elements. E@: Resistor divided, collector voltage ■ across both ends of resistor 12. A voltage proportional to E appears. on the other hand,
The transistor 14 and the resistor 13 constitute an emitter follower, and the collector current of the transistor 14 is connected to the resistor 12.
It is approximately proportional to the voltage drop.

When the transistor 14 is in the off state, the drive signal ■
The power of S is directly amplified by transistors 6 and 7, and voltage V is applied to the gate of electrostatic induction type self-extinguishing element 3. E
is applied as . In order for the transistor 14 to be in the off state, it is necessary that the voltage drop between the emitter and the base of the transistor 14 be larger than the voltage drop across the resistor 12. Voltage ■. E is less than or equal to the voltage 1 which causes a voltage drop across the resistor 12 to exceed the voltage drop between the emitter and base of the transistor 14. When VGE exceeds this voltage (1), the transistor 14 begins to flow a collector current, and the current value is approximately proportional to the voltage drop across the resistor R12, as described above.

Therefore, this collector current causes a voltage drop in the resistor 10, the value of the drive signal VS drops, and the gate voltage VGE of the electrostatic induction type self-extinguishing element 3 drops accordingly. This drop will continue until the collector voltage VcE drops to a voltage (1) at which the collector current of the emitter follower no longer flows. In addition, the collector voltage of the electrostatic induction type self-extinguishing element 3 is ■. If the voltage E continues to rise, and the voltage across the resistor 12 exceeds the predetermined voltage ■2, the Zener diode 15 acts to suppress any further voltage rise, so the drive signal S does not fall below a certain value. Therefore, VGE is maintained at a predetermined lower limit value.

Figure 3 shows such a gate voltage V. FIG. 3(a) is a graph illustrating the effect of controlling E, and FIG. 3(a) shows the same collector voltage as in FIG. In order to avoid latch-up phenomenon in the graph showing the relationship between [ and collector current IC]
I indicating c-20A! ilA, and the gate voltage ■ and collector voltage V in the graph of Figure 3.
The E obtained by plotting cE is song IIB in Fig. 3(b). On the other hand, the line C is obtained by performing the same linear approximation as in FIG. 2, and the gate voltage V
. The maximum value of E is transistor 1, which becomes an emitter follower.
It can be determined as appropriate by appropriately selecting the characteristics of 4 and the values of resistors 11 and 12 that perform resistance division.
Gate voltage■. The minimum value of E can be appropriately determined by selecting the characteristics of the Zener diode. By controlling the gate voltage VGE of the electrostatic induction type self-extinguishing element within a predetermined range in this manner, the current flowing through the electrostatic induction type self-extinguishing element is always equal to or less than the maximum allowable current.

4 to 7 are circuit diagrams showing some other embodiments of the present invention.

FIG. 4 shows a series resistor 16 added to the zener diode 15 in FIG. 1, and since a voltage drop occurs due to the series resistor, the collector voltage of the electrostatic induction self-extinguishing element is .

Gate voltage ■ when E increases. E has a characteristic like the broken line in the graph of FIG. This makes it possible to more accurately approximate the constant current characteristics of the electrostatic induction type self-extinguishing element.

In Figure 5, Zener diodes 17 and 18 are connected respectively to the collector side and base side of the transistor that becomes the emitter follower for the circuit in Figure 1, and the Zener diode between the base and emitter and the resistor on the emitter side are omitted. This figure shows another example. In this circuit, the gate voltage of the electrostatic induction self-extinguishing element is set by the Zener diode 17.18. , the collector voltage that changes
. The value of E and V2 can be approximated, and the game
Voltage ■. E changes binary. Although the characteristics in this example do not closely approximate the song NIB in FIG. 3(b), they are sufficient for practical use.

Figure 6 shows the zener diode 17 in Figure 5 as a resistor 1.
9 and omitting the zener diode 18, the basic characteristics are the same as in the case of FIG.

FIG. 7 shows the details of a control circuit that supplies the drive signal S to the configuration shown in FIG.

According to this, the control signal VQ is inputted to one side of the AND circuit 20, and its output becomes the drive signal ■S, and the resistor 10
is applied to On the other hand, the current flowing through the transistor 14 is detected by the light emitting diode of the photocoupler 22, and the resistor 2 is used to generate a photocurrent in the phototransistor on the receiving side.
4 is input to the set terminal (S) of the time delay circuit 25, this output is held by the latch circuit 26, and the output is input to the AND circuit 20.
is input to the other side input terminal. In this circuit, when the control signal Va rises, the time delay circuit 25 is reset, but if the collector current detected by the photocoupler 22 continues to flow for longer than a predetermined time determined by the time delay circuit 25, that is, an overcurrent occurs. Therefore, the collector voltage V of the electrostatic induction type self-extinguishing element 3. When it is detected that the accident state in which E does not decrease continues, the accident state is held in the latch circuit 26, so the AND circuit 20
The output ■S is turned off, and the electrostatic induction type self-extinguishing element 3 is turned off, thereby protecting the electrostatic induction type self-extinguishing element 3.

In the above embodiment, the electrostatic induction type self-extinguishing element has an I
In addition to GT, there is FE. In addition, in the embodiment, there is only one electrostatic induction type self-extinguishing element, but in reality, four or six electrostatic induction type self-extinguishing elements are connected with opposite polarity between the collector and emitter of the electrostatic induction type self-extinguishing element. Bridges are often used.

Furthermore, although the voltage adjustment point of the voltage adjustment circuit made of emitter follower transistors is connected to the input side of the amplification transistor of the gate voltage adjustment circuit in each of the above embodiments, it may be connected to the output side. However, in this case, the loss of the entire drive circuit increases slightly.

〔Effect of the invention〕

As described above, according to the drive circuit for an electrostatic induction type self-extinguishing element according to the present invention, the gate of the electrostatic induction type self-extinguishing element is controlled according to the detected collector voltage of the electrostatic induction type self-extinguishing element. Since a voltage adjustment circuit that lowers the voltage is provided, the collector current can be maintained below a predetermined maximum allowable value, and deterioration of the electrostatic induction type self-extinguishing element can be prevented.

Further, in the case where the gate voltage of the electrostatic induction type self-extinguishing element is prevented from dropping below a predetermined value, the occurrence of loss can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a drive circuit for an electrostatic induction type self-extinguishing element according to the present invention, FIG. 2 is a graph showing the operation of FIG. 1, and FIG. 3 is a graph showing the effects of the present invention. , FIGS. 4 to 7 are circuit diagrams showing other embodiments of the present invention, FIGS. 8 and 9 are graphs showing the characteristics of static induction type self-extinguishing elements, and FIG. 10 is a circuit diagram showing other embodiments of the present invention. FIG. 2 is a circuit diagram showing a drive circuit for an electric induction type self-extinguishing element. 1...DC 14ilG! , 2...Load, 3...Static 1! Inductive self-extinguishing element, 4...gate power supply, 5,
8,10°11.12,13.19.24...Resistance,
6,7゜14...transistor, 9...diode, 15゜17.18...zener diode, 20...
・AND circuit, 22... Photocoupler, 25... Time delay circuit, 26... Latch circuit. Figure 1 Figure 2 Core voltage (VCE) Figure 3 (a) Core voltage (VCE) (b) Core voltage (voE) Figure 4 Heat Figure 5 Figure 6 Figure 8 Figure 9 Peak Collector voltage (VcE) Figure 7 Figure 10 Procedural amendment March 14, 1985 1 Indication of case 1985 Patent application No. 23334 2 Title of invention Drive circuit for electrostatic induction type self-extinguishing element 3 Amendment Relationship between the persons who write the information Patent applicant (307) Toshiba Corporation 4th generation Buried person 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Telephone Tokyo (211) 2321 Representative 8 Contents of the amendment (1) Details 1, page 3, line 15 “l n5ula −
Correct ted J to [I n5ulatedJ. (2) Same, page 3, line 17 “TransSiS-to
Correct rsJ to [TransistorsJ. (3) Insert the following sentence between lines 18 and 19 on page 13. ``In addition, in FIG. 7, the photocoupler 22a.

Claims (1)

[Claims] 1. A constant voltage power supply, and a gate voltage input circuit that applies a voltage generated from the constant voltage power supply to the gate of an electrostatic induction type self-extinguishing element in accordance with the magnitude of an input control signal. and detecting the collector voltage of the electrostatic induction type self-extinguishing element, and lowering the voltage of the control signal according to the detected collector voltage to lower the gate voltage of the electrostatic induction type self-extinguishing element. A drive circuit for an electrostatic induction self-extinguishing element, comprising: a voltage adjustment circuit for controlling the voltage; 2. A drive circuit for a static induction type self-extinguishing element according to claim 1, wherein the gate voltage input circuit comprises two complementary-connected transistors. 3. The electrostatic induction type according to claim 1, wherein the voltage adjustment circuit is an emitter follower circuit that flows a collector current according to the voltage between the emitter and the base, and the collector is connected to the input point of the gate voltage input circuit. Drive circuit for self-extinguishing element. 4. A drive circuit for a static induction type self-turn-off element according to claim 3, wherein the voltage between the emitter and the base is obtained by resistive division of the collector voltage of the static induction type self-turn-off element. 5. The electrostatic induction self-extinguishing device according to claim 4, wherein the voltage regulating circuit does not reduce the gate voltage when the gate voltage of the electrostatic induction self-extinguishing element reaches a lower limit value. Arc element drive circuit. 6. A drive circuit for a static induction type self-extinguishing element according to claim 5, comprising a constant voltage diode connected between the emitter and base of the emitter follower circuit. 7. The electrostatic induction type self-extinguishing device according to claim 1, wherein the electrostatic induction type self-extinguishing element is turned off by turning off the control signal when the gate voltage drop operation of the voltage regulating circuit continues for a predetermined time or more. Drive circuit for electric induction type self-extinguishing element. 8. A drive circuit for an electrostatic induction type self-extinguishing element according to claim 7, wherein the gate voltage drop operation is detected by a photocoupler.