JPH0435410A - Semiconductor switch device - Google Patents

Abstract

PURPOSE:To shorten the interruption time of a main circuit current as a semiconductor switch by providing the semiconductor switch consisting of a first semiconductor element and a second semiconductor element connected to a part of the first semiconductor element in parallel, and a driving signal generation circuit. CONSTITUTION:The semiconductor switch 3A consisting of the first semiconduc tor element inserted into a main current path and the second semiconductor element 2 connected to a part of the first semiconductor element 1 in parallel is given. When the second semiconductor element 2 is turned off because a driving signal from the driving signal generation circuit 9 is eliminated, a base current is supplied to the first semiconductor element 1 and the first semiconduc tor element 1 is turned off. When the second semiconductor element 2 is turned off by the driving signal from the signal generation circuit 9 on the other hand, the base current of the first semiconductor element 1 is bypassed by the second semiconductor element 2 and the first semiconductor element 1 is turned off. Thus, the interruption time of the main circuit current as the semiconductor switch becomes short.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a semiconductor switch including a first semiconductor element and a second semiconductor element connected in parallel, and a semiconductor switch including a drive signal generation circuit for the semiconductor switch. It is related to the device.

1 Prior Art] FIG. 6 shows, for example, an INTERNATIONAL RECTIFIE.
HEXFET DATABOOK published by R) in 1982.
) is a circuit diagram showing a partial block diagram of an example of a conventional semiconductor switch device published in pages A-III to A-122;

In FIG. 6, (1) is a first semiconductor element such as a bipolar transistor (hereinafter simply referred to as a transistor);
(2) is a second semiconductor element, for example a MOSFET;
The transistor (1) and the MOSFET (2) constitute a semiconductor switch (3) by connecting the emitter E of the transistor (1) and the drain D of the MOSFET (2) in series. (4) constitutes a protection circuit (hereinafter referred to as a snubber) for the semiconductor switch (3), in which a constant voltage tie-out (hereinafter referred to as a zener diode) and a capacitor are connected in parallel. This snubber (4) has one end connected to the base terminal B of the semiconductor switch (3) for the base B of the transistor (1), and the other end connected to the base terminal B of the semiconductor switch (3) for the source S of the MOSFET (2). 3) Source terminal S
are connected to each. (5) is a current transformer, whose primary winding (5a) or collector C of transistor (1)
It is connected between the collector terminal C and the terminal P of the semiconductor switch (3) for use, and one end of its secondary winding (5b) or the source terminal S of the semiconductor switch (3) is connected to the other end or the diode ( 6) to terminal B of the semiconductor switch (3). (7) and (8) are a load and a DC power supply connected in series between the terminal P and the terminal N connected to the sos terminal S, respectively. (9) is a semiconductor switch (
Base terminal B of 3), gate G of MOSFET (2)
This is a drive signal generation circuit that is connected to the gate terminal G of the semiconductor switch (3) and the source terminal S of the semiconductor switch (3) for supplying a drive signal, which will be described later, to make the semiconductor switch (3) function.

Next, the operation of the conventional semiconductor switch device shown in FIG. 6 will be explained with reference to FIG. 7 as well.

First, before time t1, as shown in FIG. 7(F), a voltage V equal to the voltage 6 of the DC power supply (8) is applied between the terminals P and N.
It's PN. Since the gate voltage of MOSFET (2) is ~76 or zero, MOSFET (2) is in an off state, and transistor (1) is also in an off state.

Next, at time t, the gate voltage V of MOSFET (2)
As shown in FIG. 7(A), raise cs from zero to a certain positive value (for example, about 15 V) to turn on MOSFET (2), and at the same time turn on transistor (1), as shown in FIG. 7(B). ) When the base current IB of one initial drive pulse shown in FIG. Current ■. Or the flow stops.

At this time, if the turns ratio of the current transformer (5) is n, then
The secondary winding (5b) has an IC7 shown in FIG. 7(D).
A current of 0-Ic/n flows through the diode (6), transistor (1), and MOSFET (2).
flows through. Therefore, this current I C70 flows into the seventh transistor (1) due to the positive feedback action of the current transformer (5).
It is supplied as a base current 8 shown in FIG.

Next, time 1. The gate voltage Vc of MOSFET (2) at
5 from about 15V mentioned above to zero, MOSFET (
Although the transistor (2) is turned off, the transistor (1) collector E i'jt l (does not immediately become zero and continues until time t3 when the blocking ability between the collector of the transistor (]) and the hearth 8 is restored. At time 13, the transistor (1) turns off and the collector current I is about to be cut off, but at that time, a voltage due to the back electromotive force is generated between the collector C of the transistor (1) and the Hess 3. Therefore, the current J -C-dV/dt, that is, the change in voltage between collector C and base 8
In between, the base current IB flows in the opposite direction through the pantance into the snubber (4). Next, at time t4, when the voltage change due to the reverse power generated between the collector (C) and the base (B) disappears, the collector current 1c is finally completely cut off, and the transistor (1), MOSFET
(2) and the current transformer (5) in series, the voltage VPN rises to the level of the power supply voltage VF, and finally the F run/meta (]) and MO3FET (2) are turned off. I will do it.

Figure 8 shows, for example, the ``MITSUBISHI SEM'' published by Mitsubishi Electric Corporation in 1986.
FIG. 3 is a circuit diagram showing another example of the conventional semiconductor switch device published in No. 1-14 Beno of ICONDUCTOR3) +986-BOWER MODULE.

In FIG. 8, (]), (7) and technique (8) are exactly the same as those shown in FIG. 6. (9A) is a drive signal generation circuit that supplies a drive signal to the transistor (1),
A transistor (91) that supplies a base current to turn on the transistor (1) (hereinafter simply referred to as an on-base current supply transistor) (91), a collector of this on/base current supply transistor (91) and a transistor (
1) a limiting resistor (92) connected between the base B of
a transistor whose emitter is connected to the base B of the transistor (1) and supplies a base current and voltage in the opposite direction to turn off the transistor (1) (hereinafter simply referred to as an off-bias transistor) (93); A photocoupler (94) consisting of a light emitting diode that converts the drive signal input to the drive signal generation circuit (9A) into an optical signal and a phototransistor that converts the optical signal into an electrical signal.
, the input side is connected to the collector of the phototransistor in this photocoupler (94) (95)
and an inverting buffer (96), a limiting resistor (97) connected between the output side of the buffer (95) and the base of the on-base current supplying transistor (91), and an inverter (
96) and the on-buffer transistor (93)
), a limiting resistor (99) connected between the collector of the phototransistor and the emitter of the on-base current supplying transistor (91); It has a limiting resistor (100) connected between the emitter and the collector of the off-biasing transistor (93). (101
) and (102) are DC power supplies (hereinafter simply referred to as drive circuit DC power supplies) that supply DC voltage to the drive signal generation circuit (9A).

Next, the operation of the conventional semiconductor switch device shown in FIG. 8 will be explained with reference to FIG. 9 as well.

First, before time t, a voltage V equal to the voltage VE of the DC power supply (8) is applied between the terminals P and N as shown in FIG. 9(D).
PN is on. Since no drive signal is input to the primary side of the photocoupler (94), the phototransistor on the input side is in an off state. Therefore, the voltage of the DC power supply (101) is directly applied to the input sides of the buffer (95) and the reversing buffer (96), so the potential is at a high level, and the outputs of the buffer (95) and the reversing buffer (6) The sides are at high and low potentials, respectively. Therefore, the on-base current supply transistor (91) is in the off state and
Since the bias transistor (93) is in the on state, the transistor (1) is in the off state.

Next, at time t, when the drive signal shown in FIG. 9(A) is input to the primary side of the photocoupler (94), the phototransistor on the secondary side is turned on, so that the buffer ( The primary sides of the buffer (5) and the inversion buffer (96) are at a low level, and the secondary sides of the buffer (5) and the inversion buffer (6) are at a low level and a high level, respectively. Therefore, the off-bias transistor (93) is in the off state, or the on-base current supply transistor (91) is in the on state. current J
B is supplied and transistor (1) turns on immediately.

As a result, the collector current I shown in FIG. 9(C). But the flow stops. As long as the drive signal is input, the on-base current supply transistor (91) maintains the on state and continues to supply the base current IB to the transistor (1), so the on state of the transistor (1) is maintained. be done.

Next, at time t, when the drive signal input to the primary side of the photocoupler (94) disappears, the phototransistor on the secondary side turns off, so the buffer (94)
5) and the primary side 1j11 of the inversion buffer (96) become high level again, and the secondary sides of the buffer (95) and the inversion buffer (96) return to the high level and low level, respectively. Therefore, the on-base current supply transistor (91) returns to the off state, the automatic bias transistor (93) returns to the on state, and the DC type # (102
) is applied, the base voltage aIB supplied to the base B of the transistor (1) switches from the forward direction to the reverse direction, but the collector current I of the transistor (1). It quickly becomes zero and continues until time t3 when the carriers accumulated in the base of the transistor (1) disappear and the blocking ability of the collector C and base B of the transistor () is restored. Then, at time t, transistor (1) is turned off, and the collector current becomes ■. is cut off, and as a result, the terminal voltage between terminals P and N is PN, which is the main circuit DC power supply voltage. rise to the level of

[Problem to be solved by the invention] As described above, the conventional semiconductor switch device is a MOSFE
Since T (2) is connected in series with the emitter E of transistor (1), a snubber (4) is essential as an overvoltage protection when MOSFET (2) is turned off, making its configuration complicated and Since the current corresponding to the collector current of the main circuit must be absorbed, the capacity becomes large, and there is also the problem that the current cutoff time as a semiconductor switch becomes long.

Furthermore, since the conventional semiconductor switch device adopts the base current reverse direction cancellation method as described above, the drive signal generation circuit necessarily includes an off bias supply transistor (93), Reversing buffer (96), limiting resistor (9
8) and (lOO), the off-no-earth supply DC power supply (102), and the above-mentioned circuit components necessary to explain the essential functions and operations described above, in addition to the above-mentioned circuit components, directly or indirectly. required the necessary control circuit components to operate normally.

Therefore, the drive signal generation circuit requires both a forward direction circuit system and a reverse direction bias circuit system, and the number of parts and circuit configuration are double compared to a forward direction circuit system only, making it more complicated. However, there were problems such as the power consumed by the circuit (required power) doubled. Furthermore, in the base current reverse bias method, in order to speed up the cut-off time, the carrier accumulation phenomenon in the Hess layer that is inherent in a transistor, which is a semiconductor switch, and the coordination with the reverse bias circuit system in the drive signal generation circuit are used. The problem is that there is a limit to the cut-off time.

That is, as mentioned above, conventional semiconductor switch devices have disadvantages in terms of economy, quality, function, and reliability.

The present invention was made to solve the above-mentioned problems, and it is possible to simplify the structure of a semiconductor switch device, especially the structure of a semiconductor switch and its drive signal generation circuit, and also to simplify the structure of a semiconductor switch and its drive signal generation circuit. It is an object of the present invention to obtain a semiconductor switch device that can shorten the circuit current cutoff time.

; Means for Solving the Problems] A semiconductor switch device according to the present invention includes a first semiconductor element inserted into a main current path and a second semiconductor connected in parallel with a part of the first semiconductor element. The device is provided with a semiconductor switch consisting of an element, and a drive signal generation circuit connected to the semiconductor switch and supplying a drive signal for driving the semiconductor switch on/off.

Function 2 In this semiconductor switch device, when the semiconductor switch device is turned off due to the loss of the drive signal from the 12 (7) semi-solid element or drive signal generation circuit, the base current is supplied to the first semiconductor element and the first semiconductor element is turned off. turns on. Conversely, when the second semiconductor element is turned on by a drive signal from the signal generation circuit, the base current of the first semiconductor element is bypassed to the second semiconductor element, and the first semiconductor element is turned off.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a partial block diagram of a first embodiment of a semiconductor switch device according to the present invention, and the conventional semiconductor switch device shown in FIG.
) is connected in parallel with MOSFET (2) to form a semiconductor switch (3A).
The emitter E of 1) is electrically directly connected to the source terminal S of the semiconductor switch (3A), and the train D of MOSFET (2) is connected to the hess B of the transistor (1). Remove Yo and snubber (4) and 1 is different here.

Next, the operation of the first embodiment will be explained with reference also to FIG.

First, before time 11, as shown in FIG.
Since a predetermined positive gate voltage V65 (for example, about 15 V) is supplied to MOSFET (2), the MOSFET (2) is turned on. Also, transistor (1) is in an off state.

Further, as shown in FIG. 2(F), a voltage VPN equal to the voltage VE of the DC power supply (8) is applied between the terminals P and N.

Next, time 1. , the gate voltage V of MOSFET (2)
In order to lower os from a positive voltage to zero to turn off MOSFET (2) and turn on transistor (1) at the same time, a drive signal generation circuit generates a base current IB of one initial drive pulse shown in Fig. 2(b). When (9) is supplied to transistor (1), this transistor (1) is turned on immediately. As a result, the flow of the collector current IC shown in FIG. 2(C) is reduced. At this time, the current transformer (
If the turns ratio of 5) is n, then its secondary winding (5b
) is shown in FIG. 2(D). A current of Tp=I c/n flows, and this current flows through the tie-out (6) and the transformer 7 star (1).

However, this current I. 1. is supplied to the transistor (1) as a base current IB shown in FIG. 2(E) due to the positive feedback action of the current transformer (5), thereby maintaining the on state of the transistor (1).

Next, at time t, the gate voltage V of MOSFET (2)
Raise GS from zero to 15V mentioned above and connect MOSFET (
2) is turned on and the base B of transistor (1) is turned on.
When the base current IB supplied to the MOSFET (2) is bypassed, the transistor (1) becomes short of hFE, but the collector current Ic does not immediately become zero and flows between the collector C and base 8 of the transistor (1). It lasts until time t3 when the stopping ability of . Then, at time t, the collector current ■. is cut off, and the voltage VPN across the series body of the transistor (1) and current transformer (5) becomes the DC power supply voltage V
The voltage rises to the level of E, and transistor (1) turns off. At this time, the time until the blocking ability between the collector C and the base 8 of the transistor (1) is recovered (time t3, time t2), the collector current 1c that continues to flow, and the secondary current of the current transformer (5). The difference from the current I C70 flowing from the winding (5b) flows into the MOSFET (2) as a base current IB in the opposite direction.

FIG. 3 is a modification of the first embodiment shown in FIG. 1, in which a bipolar transistor (10) is used instead of the MOSFET (2) as the second semiconductor element, and the second semiconductor element is a bipolar transistor (10). The same operation and effect as in the embodiment is achieved.

FIG. 4 is a circuit diagram showing a second embodiment of the semiconductor switch device according to the present invention, and the conventional semiconductor switch device shown in FIG. 8 has a semiconductor switch (3) instead of the transistor (1). and drive signal generation circuit (9A)
The difference is that a drive signal generation circuit (9B) is used instead. The drive signal generation circuit (9B) includes the on-base current supply trannostar (91), the limiting resistor (92), the photocoupler (94), and the buffer (
95), and limiting resistance (97), (99),
7 stars of gate signal supply transistors whose collectors are connected to the emitters of on-base current supply transistors (9) and whose emitters are connected to gate G of MOSFETs (2) to supply gate signals to gate G of MOSFETs (2); (]
03), and this gate signal supply transistor (10
3) and the output side of the buffer (95). Note that the emitter of the phototransistor in the photocoupler (94) is connected to the source S of the MOSFET (2). This is the only DC power supply for the drive signal generation circuit (9B).

Next, the operation of the second embodiment will be explained with reference also to FIG.

First, before time t, as shown in FIG. 5(A), no drive signal is input to the primary side of the photocoupler (94), so the phototransistor 7 star on the secondary side is in the off state. be. Therefore, since the voltage of the DC power supply (305) is directly applied to the input side of the sofa (95), the potential is at a high level, and the output side is also at a high level. Therefore, the on-base current supply transistor (9
1) is in the off state, or on the other hand, since the base potential of the gate signal supply transistor (103) is at a high level, the gate signal supply transistor (103) is in the on state, so the gate G of MOSFET (2) The fifth
A blank signal is input to the figure (B), and the MOSFET (
2) is in the on state. Moreover, as shown in FIG. 5(E), a voltage V equal to the voltage vE of the DC power supply (8) is applied between the terminals PN.
PN is on.

Next, at time t, when a drive signal is input to the primary side of the photocoupler (94), the buffer (95) becomes low in potential on both its input and output sides, as in the conventional example. level, and the on-base current supply transistor (91
) turns on, and on the other hand, the gate signal supply transistor (103) turns off, so MOSFET (2
) is turned off. Since the base current IB shown in FIG. 5C is supplied to the base B of the transistor (1), the transistor (1) is immediately turned on. As a result, a collector current of 1° begins to flow as shown in FIG. 5(D). As long as the drive signal is input, the on-base current supply transistor (91) maintains the on state and the MOSFET (2) maintains the off state, so that the base B of the transistor (1) base electric i
M I B is continuously supplied to keep the transistor (1) on.

Next, at time t, when the drive signal on the primary side of the photocoupler (94) disappears, the phototransistor on the secondary side is turned off again, so that the input and output sides of the buffer (95) are The potential becomes high level again. Then, the on-base current supply transistor (91) is turned off again, while the gate signal supply transistor (1
03) is turned on again and a gate signal is input to the gate G of MOSFET (2), so MOSFET (
2) turns on. Therefore, this MOSFE
By turning on T(2), i.e. transistor(1)
Due to the carrier emission effect due to the short circuit between the base and emitter of
1) Collector current I at time t3 when the blocking ability between collector C and base 3 is completely recovered. becomes zero and transistor (1) is turned off. As a result, terminal PN
The terminal voltage vPN between them is raised to the level of the main circuit DC power supply voltage VE.

In addition, in the above-mentioned second embodiment, the MOSFET (2) is provided for the base-emitter lL'5 u circuit operation when the transistor (1) is turned off.
Even if a normal trans/meta, thyristor, GT○, etc. is used in place of the OSFET (2), the same operation and effect as in the above embodiment can be achieved.

In addition, although the MOSFET (2) in the second embodiment and the transistor, thyristor, GT○, etc. in the modification described above are provided directly between the base and emitter of the transistor (1), it is necessary to drive them. Even if it is installed in the signal generation circuit (9B), the same operation and effect as in the above embodiment can be achieved.

[Effects of the Invention] As described above, the present invention provides a first
a semiconductor switch comprising a semiconductor element and a second semiconductor element connected in parallel with a part of the first semiconductor element; and a drive signal connected to the semiconductor switch to drive the semiconductor switch on/off. Since it is equipped with a drive signal generation circuit to supply the drive signal, there is no need for a snubber, which was essentially necessary in the past, and the configuration of the drive signal generation circuit is simplified and inexpensive, and it can be used as a semiconductor switch. This has the effect of shortening the interruption time of the main circuit current and providing a high switching function.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a partial block diagram of a first embodiment of the present invention, Fig. 2 is a time chart diagram explaining the circuit operation of the first embodiment, and Fig. 3 is a circuit diagram of the first embodiment. 4 is a circuit diagram showing a second embodiment of the present invention, FIG. 5 is a time chart explaining the circuit operation of the second embodiment, and FIG. 6 is a circuit diagram showing a modification of the conventional one. A circuit diagram showing an example of a semiconductor switch device as a partial block diagram, FIG. 7 is a time chart diagram explaining the circuit operation of the conventional device shown in FIG. 6, and FIG. 8 shows another example of the conventional semiconductor switch device. The circuit diagram and FIG. 9 are time charts for explaining the circuit operation of the conventional device shown in FIG. In the figure, (1) and (]0) are transistors, (2)
are MOSFETs, (3A) and (3B) are semiconductor switches, (5) (5a) and (5b) are current transformers, respectively, their j-th winding and their secondary winding, (9) and (9B) are Drive signal generation circuit, (91) is on-base current supply transformer 7
The transistor (103) is a transistor for supplying gate signals. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Michiaki Soga 2 Figure 5 Figure t 2L3 7 Figure L L2 L3 L4 9 Figure Case Display Patent Application No. 2-140021 2゜3゜4゜Name of Invention Case for Person Who Amends Semiconductor Switch Device Relationship with Patent Applicant Address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki

Claims (3)

[Claims] (1) A semiconductor switch consisting of a first semiconductor element inserted into the main current path and a second semiconductor element connected in parallel with a part of the first semiconductor element; A semiconductor switch device comprising: a drive signal generation circuit that supplies a drive signal to turn on/off a semiconductor switch. (2) A feedback current transformer is provided, its primary side is connected to the main current path of the first semiconductor element, and its secondary side is connected to the control current path of the first semiconductor element, and the drive signal is 2. The semiconductor switch device according to claim 1, wherein a single pulse for initial driving is supplied from a generating circuit to said control current path. (3) An on-base current supply transistor that supplies a base current for the drive signal generation circuit to turn on the first semiconductor element, and a control signal supply that supplies a control signal for turning on the second semiconductor element. and a transistor for
2. The semiconductor switch device according to claim 1, wherein only one of the transistors is always turned on.