JP3350562B2 - "Switching circuit with on / off detection function and main current detection function", "switching circuit with on / off detection function, self-holding function and self-turn-off function", "on / off detection function and main current detection function Switching circuit with on / off detection function, self-holding function and self-turn-off function " - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The first invention relates to a "switching circuit having an on / off detection function and a main current detection function". Function to detect whether it is greater than. The first invention has the first effect that "the ON voltage of the switching circuit and the energy loss due to the ON voltage can be reduced" and that the "current for ON / OFF detection does not affect the detection of the main current of the switching circuit". There is a second effect. The second effect is that it is not necessary to limit the magnitude of the on / off detection current, so that the current value is increased to a value that is not affected by the leakage current when the switching means, which is a component, is turned off, and the "erroneous ON / OFF detection can be prevented. " The second effect is that even if the capacitance between the two main terminals of the switching means is as large as the capacitance between the drain and the source of the MOS-FET, the large set on / off detection current causes the turn-around. -When turned off, the capacitance is quickly charged, which leads to the effect that "the delay from the actual turn-off to the off-detection can be reduced".

The second invention relates to a “switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function (= self-extinguishing function) using the switching circuit of the first invention. The second invention has an effect that "there is no need to pay attention to latch-up (on and off) due to the on / off detection current".

The third invention relates to a "switching circuit having an on / off detecting function and a main current detecting function", "a function for detecting on / off of the switching circuit", and "a main current of the switching circuit is a predetermined value. Function to detect whether it is greater than. The third invention has an effect that "the on / off detection current does not affect the detection of the main current." This effect is similar to the second effect of the first invention, in that "erroneous ON / OFF detection can be prevented" and "Even if the capacitance between the two main terminals of the switching means as a constituent element is large, its actual The delay from turn-off to off-detection can be reduced. "

A fourth invention relates to a "switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function" using the switching circuit of the third invention. In the fourth invention, "Latching by the on / off detection current"
You do not have to pay attention to up (leave it on). "

[0005]

2. Description of the Related Art First, twelve conventional on / off detection circuits are shown in FIGS. References: a) Japanese Patent Publication No. 45-15088 b) Japanese Patent Publication No. 54-44489 c) Japanese Patent Publication No. 57-56307 (parts of the thyristor 51, the transistor 5i and the diode 5d in FIG. 1) d) Japanese Patent Laid-Open No. 50 E) Japanese Patent Application Laid-Open No. 58-81332 f) Japanese Patent Application Laid-Open No. Sho 62-5019 g) Japanese Utility Model Application Laid-Open No. 60-93331 h) Japanese Patent Application No. 62-500831 (WO 87/04575) i) Japanese Patent Application No. Sho 62-504708 (WO 88/01804)

In the on / off detection circuit shown in FIG.
Current supply means formed by DC power supply 1, 2, 13 etc. "
When the switch 16 is ON, the ON / OFF detection current flows to the switch 16 without passing through the diode 10. And
The transistor 3 and the resistor 13 serving as current detecting means detect the presence or absence of the on / off detecting current. As a result, the transistor 3 is also turned on in accordance with the on / off of the switch 16,
Since the transistor is turned off, the switch 16
Can be seen. In each of the on / off detection circuits of FIGS. 3 and 4, a PNP transistor 4 is used as a current detection means.
3 are used, and these are convenient when drawing their output current. Since the switch 16 is further connected to the negative side of the DC power supply 1 in the on / off detection circuit of FIG. 4, when a controllable switch is used instead of the switch 16 and positive drive power or the like is supplied to this switch, The circuit of FIG. 4 is convenient.

On the other hand, in the on / off detection circuit of FIG. 5, "the diode 11 connected in anti-parallel to the series circuit of the switch 16 and the diode 10", the resistors 12, 13 and the like and the current supply means formed by the DC power supply 1 " When the switch 16 is turned on, an on / off detection current flows through the switch 16 without passing through the diode 10. Then, the transistor 3 and the resistor 13 serving as current detecting means detect the presence or absence of the on / off detecting current. As a result, the transistor 3 is turned on and off in accordance with the on and off of the switch 16, so that the on / off state of the switch 16 can be known from the output of the transistor 3. In each of the on / off detection circuits of FIGS. 6 and 7, a PNP transistor 43 is used as a current detection means, and these are convenient when extracting the output current. In the on / off detection circuit of FIG.
Since the switch 6 is connected to the negative side of the DC power supply 1, a controllable switch is used instead of the switch 16, and when the switch is supplied with positive drive power or the like, the circuit of FIG. 7 is convenient.

In each of the on / off detection circuits shown in FIGS. 8 to 11, the transistor 3 or 43 in each of the on / off detection circuits shown in FIGS.
This is an on / off detection circuit replaced by a channel type MOSFET. In each of the on / off detection circuits of FIGS. 12 and 13, the on / off of the switch 16 and the on / off of the transistor 3 are opposite to each other. An on / off detection circuit in which the emitter junction of each transistor 3 is replaced by the emitter junction of a PNP transistor is also possible.

In the on / off detection circuit of FIG. 5, a circuit or the like (not shown) connected between both terminals t45 and t46 applies a reverse voltage to the diode 11 while the switch 16 is on. Is kept off, the on / off detection current flows not through the diode 11 but through the circuit or the like.
This applies to the on / off detection circuits of FIGS. 6, 7, 10, 11, and 13. A circuit or the like (not shown) connected between the terminals t43 and t44 in the on / off detection circuit of FIG. 2 causes a current to flow backward from the terminal 43 via the DC power supply 1, the resistors 13 and 12, and the diode 10. If it is not convenient to supply the current to the terminal t44, the diode 7 (6) shown in the on / off detection circuit of FIG. 2 is required. This is the same in each of the on / off detection circuits shown in FIGS. 3, 4, 8, and 9. In such a case, FIGS.
Each of the on / off detection circuits in FIGS. 11 and 13 has an advantage that “the number of components is smaller” than each of the on / off detection circuits in FIGS. 2 to 4, 8, 9, and 12. Further, FIG.
In each of the circuits shown in FIGS. 13 to 13, a constant current means including a constant current diode can be used instead of the resistor 12.

[0010] Then, in each ON / OFF detection circuit, any type of switch including a controllable switch can be used in place of the mechanical switch 16, but a "switch having a self-holding function like a thyristor" is used. When used, it is necessary to set the magnitude of the ON / OFF detection current to be equal to or less than the holding current value so that the ON / OFF detection current does not remain. Then, in each of the on / off detection circuits of FIGS.
FET, MOS-FET, IGBT, SI irrespective of normally-on type or normally-off type instead of 3.
A T, GTO thyristor, SI thyristor, or the like may be used. In addition, it is not always necessary that the transistor 3 and the like be completely turned on and off in response to the on and off of the switch 16, and the output state of the on-resistance, the collector current, or the drain current, etc.
It only has to change according to the off. Therefore, for example, the transistor 3 or 43 may be biased in advance in each of the on / off detection circuits of FIGS. In short, each resistor 12 has a predetermined ON
It is only necessary to be able to detect whether or not the off detection current is flowing.

Next, FIGS. 14 to 19 show six conventional current detection circuits for detecting whether the detected current is larger than a predetermined value. Reference: a) JP-A-3-179815 (FIG. 7) b) JP-A-4-11725 c) JP-A-4-58083 d) JP-A-4-68492 Both terminals t47 in the current detection circuit of FIG. If the current to be detected does not flow during t48, “DC power supply 2 and resistor 14
The ON-direction driving means formed by the transistor 4 drives the transistor 4 in the ON direction by forward biasing the base of the transistor 4 to keep the transistor 4 in the first state (including the ON state). However, the "circuit or the like (not shown) connected between the two terminals t47 and t48" causes a detected current of a predetermined value or more to flow between the two terminals t47 and t48, and the voltage drops to the diode 17 as the constant voltage means. When a forward voltage is generated (in this case, a forward drive signal), the “driving signal in the OFF direction based on this voltage drop” is supplied directly (or via the diode 8) to the transistor 4, so that the transistor 4 State (including the off state)
Is moved to.

The above-mentioned predetermined value is determined by the base current of the transistor 4, the forward voltage characteristic of the emitter junction thereof, the forward voltage characteristic of the diode 17, and the like. In some cases, the diode 8 may be omitted, or in some cases, a resistor may be connected instead of the diode 8, but the diode 8 is better. If the internal resistance of a circuit or the like connected between the terminals t47 and t48 is small, the diode 8 lowers the base potential of the transistor 4 and turns off the transistor 4 by the forward voltage of the diode 8 by the forward voltage. This is because the base potential is raised and blocked. In addition, an overcurrent flowing from the terminal t48 to the terminal t47 via the emitter junction of the transistor 4 is applied to the diode 8
Is to prevent. Then, since the diode 17 is used not as an uncontrollable switch but as a constant voltage means, as long as the constant voltage means does not prevent "the transistor 4 operates based on the magnitude of the detected current", The constant voltage means may be bidirectional.

In the current detection circuit of FIG. 15, a PNP transistor 44 is used as a detection switching means, and this circuit is convenient when its output is taken out in the form of a source (discharge) current. In each of the current detection circuits shown in FIGS. 16 and 17, a normally-on MOS FET is used, and two Zener diodes 2 are used as constant voltage means.
1 are connected in series in the opposite direction. In the current detection circuit of FIG. 16, the resistor 14 may or may not be provided. FIG.
In each current detection circuit of FIG.
Alternatively, since it is an on-direction driving means for driving the 44 in the on-direction, there is an advantage that a DC power supply is not required for the base forward bias. Therefore, when the current to be detected is larger than the predetermined value and the transistor 4 or 44 is off, the (off) output resistance of the current detection circuit becomes the value of the resistor 46. On the other hand, when it is on, its (on) output resistance is the value obtained by dividing the value of the resistor 46 by the current amplification factor of the transistor.

The circuit of FIG. 20 is a "switching circuit having a self-holding function and a self-turn-off function (= self-extinguishing function) like a GTO thyristor" using the current detection circuit of FIG. The main current (current between both main terminals t3 and t4)
Is smaller than a predetermined value (corresponding to a holding current value), the transistor 4 keeps the transistor 5 off. However, if the main current is equal to or greater than the predetermined value, the main current
The transistor 5 keeps on because the voltage drop (forward voltage) that occurs in the transistor 4 keeps off, and the switching circuit is in a self-holding state. In the switching circuit of FIG. 21, a normally-on type transistor 19 (S
IT), 20 is used, the gate reverse bias voltage of the transistor 19 is supplied from the DC power supply 18 and the like, and the gate reverse bias voltage of the transistor 20 is the sum of the forward voltage of one of the two Zener diodes 21 and the other Zener voltage. Supplied from If the polarity of the forward / reverse bias voltage of the control terminal is the same as that of each gate terminal of the transistors 19 and 20, any kind of transistor having the self-turn-off function regardless of the normally-on type and the normally-off type instead of the transistor 19 or 20 can be used. Can also be used with control switches. When a normally-off type transistor is used instead of the transistor 20, the diode 17 may be used instead of the two zener diodes 21 as in the current detection circuit of FIG.

[0015] However, the "ON / OFF switch shown in Figs.
Combining any one of the off-detection circuits "and any one of the current detection circuits in FIGS.
A switching circuit having an off detection function and a main current detection function "is configured as shown in FIGS. 22 to 25, and the switching circuit is turned on and off (that is, the switch 16 is turned on and off).
And main current (example: current between both terminals t49 and t50 in FIG. 22)
There are the following two problems when detecting. First, switching means (eg, switch 16), non-controllable switches (eg, diode 10), and constant voltage means (eg, diode 17, two zener diodes 21 connected in series in reverse). Since they are connected in series, the ON voltage of the switching circuit (eg, both terminals t49 and t in FIG. 22)
(Voltage drop between 50) and the energy loss due to this. Therefore, there is a first problem that it is desired to reduce the ON voltage of the switching circuit and the energy loss due to the ON voltage. (First problem)

Second, when the switching means (for example, the switch 16) is on, the on / off detection current (the current of the resistor 12) is supplied to the constant voltage means (for example, the diode 17, two reverse-connected series-connected elements). Since the current flows through the Zener diode 21), the ON / OFF detection current affects the detection of the main current of the switching circuit. Therefore, there is a second problem that it is desired that the on / off detection current does not affect the detection of the main current of the switching circuit. (Second problem)

Here, the influence of the main current detection of the second problem will be described in detail. For example, in the circuit of FIG. 22, when the switch 16 is on and the current between the two terminals t49 and t50 is zero, the original main current of the switching circuit excluding the current of the resistor 12 is zero. The current value of the resistor 12 must be as small as possible as compared with the "predetermined main current value serving as a reference for comparing whether the main current of the switch 16 is large" so as not to drive in the OFF direction. Otherwise, a detection error occurs. But,
If the current value of the resistor 12 is too small, the transistor 3 or the like erroneously detects a leakage current (eg, a drain cut-off current, a collector cut-off current, etc.) when the switch 16 is off, and outputs an erroneous on when the switch 16 is off. There is a risk of detection. In particular, a bipolar transistor or I
In the case of using a GBT or the like, the leakage current at the time of off increases sharply with the temperature rise. As a result, correct on / off detection cannot be performed at all with an increase in the leakage current.

Here, if the value of the resistor 12 is reduced without affecting the main current detecting operation of the transistor 4 or the like, the "current of the resistor 12 flowing when the switch 16 is on (on / off detecting current)" Can be increased to such an extent as not to be affected by the "leakage current when the switch 16 is turned off", the ON / OFF detection operation is not affected at all.

For example, in the circuit shown in FIG.
If the capacitance between both main terminals of the switch 16 is large like the capacitance between the drain and source of T, and the “current of the resistor 12 flowing when the switch 16 is on” is small,
At the time of turn-off, the current of the resistor 12 takes a long time to charge the capacitance between the two main terminals, and the detection of the turn-off is delayed from the actual turn-off.

Here, if the value of the resistor 12 is reduced without affecting the main current detecting operation of the transistor 4 or the like, the "current of the resistor 12 flowing when the switch 16 is on (current for on / off detection)". If the capacitance between the two main terminals can be quickly increased by increasing the distance between the two main terminals, the delay from the actual turn-off to the off-state detection can be reduced.

The above is not only the circuit of FIG.
The same applies to each circuit of FIG. For that reason, it is desirable that the on / off detection current does not affect the detection of the main current of the switching circuit so that the magnitude of the on / off detection current does not have to be limited. There are two problems. (Second problem)

The above two problems are caused by replacing the switch 16 in each of the on / off detection circuits of FIGS.
FIG. 26 and FIG. 27 show a “switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function” using the “switching circuit having a self-holding function and a self-turn-off function” in FIG. The same applies to the case of the configuration as described above. In the case of each of the switching circuits shown in FIGS. 26 and 27, it is necessary to limit the on / off detection current (the current of the resistor 12) to less than the holding current value so that it does not remain on. Yes "there is a problem.

[0023]

[0024]

SUMMARY OF THE INVENTION Accordingly, the first invention is directed to "the ON voltage of the switching circuit and the energy loss due to the ON voltage can be reduced, and the ON / OFF detection current affects the detection of the main current of the switching circuit. It is intended to provide a switching circuit having an ON / OFF detection function and a main current detection function.

[0025]

Another object of the present invention is to provide an on / off detection function and a self-existence function that use the switching circuit of the first invention so that "there is no need to pay attention to the on / off detection by the on / off detection current". It is intended to provide a switching circuit having a holding function and a self-turn-off function.

[0026]

The third invention further provides a switching circuit having an on / off detection function and a main current detection function that "the on / off detection current does not affect the detection of the main current of the switching circuit." It is intended to provide.

[0027]

The fourth object of the present invention is to provide an on / off detection function and a self-existence function that "uses no on-off detection by the on / off detection current" using the switching circuit of the third invention. It is intended to provide a switching circuit having a holding function and a self-turn-off function.

[0028]

That is, the first invention comprises a first switching means driven on and off, and a first switching means connected in series with the first switching means in accordance with its controllable switching direction. Non-controllable switching means, and current supply means for flowing an on / off detection current to the first switching means without passing through the first non-controllable switching means when the first switching means is on, A current detection means for detecting the on / off detection current; a forward bias direction between a control terminal and a main terminal forming a pair for inputting a drive signal thereof; and a forward direction of the first non-controllable switching means. A second switching means connected in series between the control terminal and the main terminal thereof with the first non-controllable switching means, and a main current of the first switching means is controlled by the first non-controllable switching means. A second non-controllable switching means for guiding the voltage drop between the control terminal and the main terminal in a reverse bias direction to drive the second switching means in an off direction when a voltage drop flows through the switching means; A switching circuit having an ON / OFF detection function and a main current detection function, the ON circuit driving means driving the second switching means in the ON direction when the voltage drop does not occur.

By this, "on / off of the first switching means", that is, "on / off of the switching circuit" can be known from the output of the current detecting means, and the output state of the second switching means can be determined from the output state of the second switching means. It can be determined whether the main current of the switching circuit is larger than a predetermined value.
The predetermined value is an input characteristic of the second switching means,
It is determined by the forward voltage characteristics of the first and second non-controllable switching means, the output current of the on-direction driving means, and the like.

Since the first non-controllable switching means (for example, a diode or the like) also serves as the non-controllable switching means of the on / off detection unit and the constant voltage means of the main current detection unit, The constant voltage means connected in series with the first switching means and the non-controllable switch is no longer necessary, and the voltage drop in the constant voltage means "the ON voltage of the switching circuit can be reduced, thereby resulting in energy loss Can also be reduced. 』
(First effect)

Then, "when the first switching means is on", that is, "when the present switching circuit is on", the on / off detection current is the first non-current which is also a component of the main current detection section. Since the current does not flow through the controllable switching means, the "current for on / off detection does not affect the detection of the main current of the present switching circuit. 』
(Second Effect) For this reason, it is not necessary to limit the magnitude of the on / off detection current, so that the second switching means is driven in the off direction no matter how large the on / off detection current is. You won't be left alone.

This means that the value of the on / off detection current is set to be larger than the leakage current when the first switching means is off, and it is determined whether the on / off detection current is flowing properly. If the current detecting means detects the current, the on / off detection operation does not need to be affected by the leakage current at the time of the off state, which leads to the effect that "erroneous on / off detection can be prevented". There is no erroneous detection of ON even though the first switching means is OFF, that is, even though the present switching circuit is OFF.

This means that even if the capacitance between the two main terminals of the first switching means is large, such as the capacitance between the drain and the source of the MOS-FET, the on / off detection current is reduced. If it is set to a large value, the on / off detection current rapidly charges the capacitance between the two main terminals when the first switching means is turned off, so that “from the actual turn-off to off detection”. Can reduce the delay. "

[0034]

That is, the second invention operates in accordance with the output of the second switching means in the aforementioned "switching circuit having an on / off detection function and a main current detection function" of the first invention. And an on / off driving means for driving the first switching means on when the second switching means is driven in the off direction, and for driving the first switching means off otherwise. A switching circuit having an OFF detection function, a self-holding function, and a self-turn-off function. "

As a result, the first switching means is driven on and off based on the magnitude of the main current of the present switching circuit, so that the present switching circuit has a self-holding function and a self-turn-off function. Also, the first
Since the on / off detection current does not affect the detection of the main current of the present switching circuit as described in the invention, there is no problem even if the on / off detection current is larger than the holding current value. The switching circuit according to the second aspect of the present invention has the effect that "there is no need to pay attention to the on-off state caused by the on / off detection current".
(effect)

[0036]

In other words, the third invention is a first switching means which is driven on and off, and a non-controllable serially connected to the first switching means in accordance with its controllable switching direction. A switching unit, a constant voltage unit connected outside the series connection thereof, and a main current of the first switching unit flowing to cause a voltage drop in the constant voltage direction; and when the first switching unit is on. Current supply means for supplying an on / off detection current to the first switching means without any intervention of the non-controllable switching means and the constant voltage means, and current detection means for detecting the on / off detection current A second switching means for supplying a drive signal in the OFF direction based on the voltage drop between a control terminal and a main terminal forming a pair for inputting the drive signal; Signal is a "switching circuit with on-off detection function and a main current detecting function" having, on direction driving means for driving to the on direction the second switching means when is not supplied.

With this, "on / off of the first switching means", that is, "on / off of the present switching circuit" can be known from the output of the current detecting means, and the output state of the second switching means can be determined from the output state of the second switching means. It can be determined whether the main current of the switching circuit is larger than a predetermined value.
The predetermined value is an input characteristic of the second switching means,
It is determined by the constant voltage characteristics of the constant voltage means, the output current of the ON direction driving means, and the like.

"When the first switching means is on", that is, "when the present switching circuit is on", the on / off detection current is the first non-current which is also a component of the main current detection section. Since the current does not flow through the controllable switching means, the "current for on / off detection does not affect the detection of the main current of the present switching circuit. 』
(Effects) For this reason, it is not necessary to limit the magnitude of the on / off detection current, so that the second switching means is driven in the off direction regardless of how large the on / off detection current is. It will not be.

This means that the value of the on / off detection current is set to be larger than the off-state leakage current of the first switching means, and whether the on / off detection current is flowing properly or not is determined. If the current detecting means detects the current, the on / off detection operation does not need to be affected by the leakage current at the time of the off state, which leads to the effect that "erroneous on / off detection can be prevented". There is no erroneous detection of ON even though the first switching means is OFF, that is, even though the present switching circuit is OFF.

This means that even if the capacitance between the two main terminals of the first switching means is large, such as the capacitance between the drain and source of the MOS-FET, the on / off detection current is reduced. If it is set to a large value, the on / off detection current rapidly charges the capacitance between the two main terminals when the first switching means is turned off, so that “from the actual turn-off to off detection”. Can reduce the delay. "

[0041]

That is, the fourth invention operates in accordance with the output of the second switching means in the aforementioned "switching circuit having an on / off detection function and a main current detection function" of the third invention. And an on / off driving means for driving the first switching means on when the second switching means is driven in the off direction, and for driving the first switching means off otherwise. A switching circuit having an OFF detection function, a self-holding function, and a self-turn-off function. "

As a result, the first switching means is driven on and off based on the magnitude of the main current of the present switching circuit, so that the present switching circuit has a self-holding function and a self-turn-off function. Also, the third
Since the on / off detection current does not affect the detection of the main current of the present switching circuit as described in the invention, there is no problem even if the on / off detection current is larger than the holding current value. The switching circuit according to the fourth aspect of the present invention has the effect that "there is no need to pay attention to the on-off state caused by the on / off detection current".
(effect)

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION In order to explain each invention in more detail, each invention will be described below with reference to the accompanying drawings. In the embodiment of the first invention shown in FIG. 1, each corresponds to each of the above-described components as follows. a) The switch 16 is the first switching means described above. b) The diode 10 is the first non-controllable switching means described above. c) "Resistors 12, 13 connected to both ends of switch 16"
The series circuit of the DC power supply 1 and the like "is the current supply means described above. d) "Connected body of transistor 3 and resistor 13" is the current detecting means described above. e) The transistor 4 is the second switching means described above. f) The base terminal and the emitter terminal of the transistor 4 are the control terminal and the main terminal described above. g) The diode 8 is the second non-controllable switching means described above. h) "The series circuit of the DC power supply 2 and the resistor 14 connected between the emitter and the base of the transistor 4" is the ON-direction driving means described above.

FIG. 1 shows “DC power supply 1, switch 16, diodes 8, 10, resistors 12, 13 and transistor 3”.
The on / off detection unit of the embodiment of FIG.
"ON / OFF of the switch 16", that is, "ON / OFF of the embodiment of FIG. On the other hand, a DC power supply 2, a resistor 14, a transistor 4, a diode 8,
0 constitutes the main current detector of the embodiment of FIG. 1, and it can be seen from the ON / OFF of the transistor 4 whether the main current of the embodiment of FIG. 1, that is, the current between the two terminals t41 and t42 is larger than a predetermined value. The predetermined value is determined by the base current of the transistor 4, the forward voltage characteristics of the emitter junction of the transistor 4, the forward voltage characteristics of the diodes 8, 10, and the like.

Since the diode 10 in the embodiment of FIG. 1 also serves as both the diodes 17 and 10 in the circuit of FIG. 22, one constant voltage means is not required in the embodiment of FIG. The ON voltage of the first embodiment (= both terminals t41.
along with the on-voltage during t42), it is possible to reduce the energy loss due to this. (First effect)

When the switch 16 is turned on, the on / off detection current (current of the resistor 12) does not flow through the diode 10 which is also a component of the main current detection section. The current has no influence on the detection of the main current (= current between both terminals t41 and t42) in the embodiment of FIG. (Second Effect) These effects exist in the switching circuit of the first invention including the embodiment of FIG.

Accordingly, no matter how much the magnitude of the "current for on / off detection flowing when the switch 16 is on", the transistor 4 will not be left off, so that the magnitude must be limited. There is no. This means that the capacitance between the two terminals of the switch 16 (the capacitance between the two main terminals in the case of a semiconductor switch) is equal to the drain of the MOSFET.
If the on / off detection current is large when the capacitance between the sources is large, the on / off detection current quickly charges the capacitance between both terminals when the switch 16 is turned off. This leads to the effect that “the delay from the actual turn-off to the off-detection can be reduced”.

In addition, this means that the value of the on / off detection current is set to be larger than the leakage current when the switch 16 is off (collector cutoff current or drain cutoff current in the case of a transistor). Since the off detection can be prevented from being affected by the leakage current at the time of the off, it leads to the effect that "erroneous on / off detection can be prevented".

For example, the values of the resistors 12 and 13 are set so that the current of the resistor 12 flowing when the transistor 3 is turned on becomes larger than the leakage current. Even if the leakage current is 1 milliamp,
The value of the resistor 12 is set so that the value of the on / off detection current is 10 mA or 100 mA, and the transistor 3 is turned on even if a current of about 1 mA flows through the resistor 12. The value of the resistor 13 may be set so as not to turn on. In other words, only when a current of several milliamps or more or several tens of milliamps or more flows through the resistor 12, the voltage drop of the resistor 13 causes the base voltage to drop.
What is necessary is just to set the transistor 3 to turn on so as to exceed the on-off threshold voltage between the emitters.

Alternatively, the transistor 3 outputs the first output state (including the off state) by the leakage current, and the transistor 3 outputs the second output state by the sum of the on / off detection current and the leakage current. (Including the ON state), and switches 1
When knowing the on / off state of 6, if the on / off detection current is large, the current difference is also large, and it is easy to distinguish between on and off.

It should be noted that there is a method of using a PNP transistor for the current detection instead of the transistor 3 or the like as shown in each of the circuits of FIGS. 3 and 4, and a normally-on transistor as in each of the circuits of FIGS. 8 and 9. There is also a method using a MOS FET, or a method in which the on / off of the switch 16 and the on / off of the transistor 3 are reversed, as in the circuit of FIG. In short, it is only necessary to be able to detect the presence or absence of the on / off detection current. Also, a controllable switch can be used instead of the mechanical switch 16, and any controllable switch having a self-turn-off function can be used instead of the transistor 4.

The embodiment of the first invention shown in FIG. 36 is different from the embodiment of FIG. 1 in that the present inventor sets the "PNP transistor 44 corresponding to the aforementioned second switching means" as the cathode of the diode 10. The emitter is grounded on the side.

The embodiment of the first invention shown in FIG. 37 is different from the embodiment of FIG. 1 in that the present inventor does not provide the on / off detection circuit of FIG. The embodiment of FIG. 37 has the advantage that the off detection circuit is used and that "only one DC power supply is required".

The embodiment of the first invention shown in FIG.
37 is a "switching circuit having an on / off detection function and a main current detection function" in which the main current detection unit of the embodiment of the present invention is combined with the on / off detection unit of the embodiment of FIG.

The difference between the embodiment of the first invention shown in FIG. 39 and the embodiment of FIG. 1 is that the inventor of the present invention uses the on / off detection circuit of FIG. 5 instead of the on / off detection circuit of FIG. This is because an off detection circuit is used. Therefore, "Switch 16
The series circuit of the DC power supply 1 and the diode 11 such as the resistors 12 and 13 connected to both ends of the power supply corresponds to the above-described current supply means. Also, in the embodiment of FIG.
There is an advantage that "the embodiment of FIG. 39 requires a smaller number of parts" than the case where there are 11 or the like.

The embodiment of the first invention shown in FIG. 40 is different from the embodiment of FIG. 39 in that the present inventor replaces the "PNP transistor 44 corresponding to the above-mentioned second switching means" with the cathode of the diode 10. The emitter is grounded on the side.

The difference between the embodiment of the first invention shown in FIG. 41 and the embodiment of FIG. 39 is that the present inventor does not provide the on / off detection circuit of FIG. The use of the off detection circuit has the advantage that "one DC power supply is required" in the embodiment of FIG.

The embodiment of the first invention shown in FIG.
41 is a "switching circuit having an on / off detection function and a main current detection function" in which the main current detection unit of the embodiment of the present invention is combined with the on / off detection unit of the embodiment of FIG.

The embodiment of the second invention shown in FIG.
This is a “switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function” that combines the switching circuit of FIG. 1 with the embodiment of the first invention shown in FIG. In the embodiment of FIG. 43, each corresponds to each of the above-described components as follows. a) The transistors 5 and 4 serve as the first and second switching means described above. b) The base terminal and the emitter terminal of the transistor 4 are the control terminal and the main terminal described above. c) The diodes 10, 8 serve as the first and second non-controllable switching means described above. d) “The resistors 12, 1 connected to both ends of the transistor 5
3 and the DC power supply 1 in a series circuit ”as the current supply means described above. e) "Connected body of transistor 3 and resistor 13" is the current detecting means described above. f) "The series circuit of the DC power supply 2 and the resistor 14 connected between the emitter and the base of the transistor 4" is the ON-direction driving means. g) "The gate drive circuit formed by the DC power supply 2, the transistor 4 (the Zener diode 9) and the resistor 15 is the on / off drive means described above.

"DC power supply 2, resistor 14, transistor 4
43 detects the main current of the embodiment of FIG. 43, that is, the current between both terminals t1 and t2, and when the main current is larger than a predetermined value, the main current detector detects the main current. Keep transistor 5 on through the gate drive circuit, otherwise keep transistor 5 off.
The embodiment of FIG. 43 inherits the effect of the first invention of the embodiment of FIG. 1 as it is, and the current (on / off detection current) of the resistor 12 does not affect the detection of the main current. There is no problem even if the current of No. 12 is larger than the holding current value, and it is not necessary to pay attention to turning on and off by the on / off detection current (current of the resistor 12). 』
(Effects) Such effects exist in the switching circuit of the second invention including the embodiment of FIG.

The embodiment of the second invention shown in FIG.
And a switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function, which is a combination of the switching circuit of FIG.

The embodiment of the second invention shown in FIG.
This is a “switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function” that combines the switching circuit of FIG. 1 with the embodiment of the first invention shown in FIG. The embodiment of the second invention shown in FIG. 46 is a combination of the switching circuit of FIG. 21 and the embodiment of the first invention shown in FIG. Circuit ". In either embodiment, normally on transistor 19 (SI
T) and 20 (MOS-FET) correspond to the first and second switching means described above, and the "diode 10 and zener diode 21 connected in series in the opposite direction" correspond to the first non-controllable switching means described above. Equivalent to
"DC power supplies 2 and 18, transistor 20 and resistor 15,
The gate circuit formed by 47 "corresponds to the on / off driving means described above.

As described above, in order to obtain the gate reverse bias voltage of the transistor 20, the forward voltage (= the forward voltage of the diode 10 and the Zener diode 2)
A non-controllable switch having a larger zener voltage (1) may be used. The main current detector similarly drives the transistor 19 through the gate drive circuit.
Instead of the transistor 19 or 20, any type of controllable switch can be used as long as it has the same polarity of the forward / reverse bias voltage of the control terminal and has a self-turn-off function. When a normally-off controllable switch is used in place of the transistor 20, the diode 10 may be used alone, as in the circuits shown in FIGS. 43 and 44, and the zener diode 21 may not be used.

The embodiment of the second invention shown in FIG.
3 is a three-terminal switching circuit to which the embodiment of FIG.
The power supply capacitor 23 and the like constitute the DC power supply 2 of the embodiment of FIG. 43. When the transistor 22 is on, the DC power supply 48 passes through the diode 49, the resistor 50, the power supply capacitor 23, the Zener diode 51, and the diodes 52 and 53, and The charging current flows to 22. In the embodiment of FIG. 47, transistor 3 prevents transistor 22 from turning on as long as transistor 5 is on.
On the other hand, as long as the transistor 22 is on, the transistor 22 itself prevents the transistor 5 from turning on. As a result, the transistors 5 and 22 are not turned on at the same time. (Reference: JP-A-3-1798)
No. 15)

The charging current from the power supply capacitor 23 passes not through the Zener diode 51 and the diodes 52 and 53 but through the diodes 54 and 55 to the transistor 2.
If it is desired to prevent the current from flowing to 2, a Schottky barrier type having a small forward voltage is used for the Zener diode 51 and the diodes 52 and 53, and a normal type having a large forward voltage is used for the diodes 54 and 55. Zener diode 5
1 may be a parallel circuit of a normal Zener diode and a Schottky barrier diode. When the transistor 22 is on, the current of the resistor 14 is
Does not flow to the transistor 22 through the emitter junction and the diodes 54 and 55, but flows to the transistor 22 through the diodes 8 and 55, so that the transistor 4 is turned off. As a result, while transistor 22 is on, transistor 4 cannot keep transistor 5 off, but instead transistor 22 keeps transistor 5 off. Therefore, detection of the main current of the transistor 5 by the transistor 4 and the like is limited to the period during which the transistor 22 is off. Further, the transistor 56
May be removed, and the resistances 57 and 58 may be set to zero.

The embodiment of the first invention shown in FIG. 48 is a three-terminal switching circuit constituted by using two switching circuits of the first invention. Transistors 59 and 60 are IG
BT. Two main current detectors (transistor 44 and the like and transistor 61 and the like) and two ON / OFF detectors (the transistor 43 and the like and transistor 3 and the like) are shown on the transistor 59 side. These may be used one by one or two at a time. As means for driving the transistor 61 in the ON direction, the resistor 4 in the current detection circuit of FIG.
Unlike FIG. 6, a constant current diode 62 is used instead of a resistor.

The embodiment of the first invention shown in FIG. 49 is also a three-terminal switching circuit constituted by using two switching circuits of the first invention. Two types of ON / OFF detection units (the transistor 43 and the like and the transistor 3 and the like) are shown on the transistor 63 side. Transistor 6 such as transistor 44
If the main current detection of 4 is limited to the ON period of the transistor 64, the DC power supply 65 is not required.

In the third embodiment of the present invention shown in FIG. 28, the following correspond to the respective components described above. a) The switch 16 is the first switching means described above. b) Diode 10 is the non-controllable switching means described above. c) The diode 17 serves as the constant voltage means described above. d) “The series circuit of the DC power supply 1 and the resistors 12 and 13 connected to both ends of the switch 16” is the current supply means described above. e) The "connection body of the transistor 43 and the resistor 13" is the current detecting means described above. f) The transistor 4 is the second switching means described above. g) The base terminal and the emitter terminal of the transistor 4 are the control terminal and the main terminal described above. h) "The series circuit of the DC power supply 2 and the resistor 14 connected between the emitter and the base of the transistor 4" is the ON-direction driving means described above.

"DC power supply 2, transistor 43, resistor 1
2, 13, diode 10 (, 6, 7) and switch 1
"6" constitutes the ON / OFF detection section of the embodiment of FIG. 28, and "ON / OFF of the switch 16", that is, "ON / OFF of the embodiment of FIG. 28" can be understood from ON / OFF of the transistor 43. On the other hand, the DC power supply 2, the resistor 14, the transistor 4, and the diode 17 (8) constitute the main current detecting section of the embodiment of FIG.
It can be seen whether the main current of this embodiment, that is, the current between both terminals t60 and t61 is larger than a predetermined value. The predetermined value is determined by the base current of the transistor 4, the forward voltage characteristics of the emitter junction of the transistor 4, the respective forward voltage characteristics of the diodes 17 (8), and the like.

When the switch 16 is turned on, the on / off detection current (the current of the resistor 12) does not flow through the diode 17, which is a component of the main current detection unit.
"The on / off detection current does not affect the detection of the main current (= current between both terminals t60 and t61) in the embodiment of FIG. 28 at all. (Effects) Such effects exist in the switching circuit of the third invention including the embodiment of FIG.

Therefore, no matter how large the magnitude of the “on / off detection current that flows when the switch 16 is on”, the transistor 4 will not be kept off, so that the magnitude must be limited. There is no. This is the first
As in the case of the invention, the capacitance between both terminals of the switch 16 (the capacitance between both main terminals in the case of a semiconductor switch) is M
In the case where the capacitance between the drain and the source of the OS / FET is large, the on / off detection current is increased when the switch 16 is turned off. Since the capacity is charged quickly, it leads to the effect that "the delay from the actual turn-off to the off-detection can be reduced".

In addition, this means that the value of the on / off detection current is changed to the leakage current when the switch 16 is turned off (in the case of a transistor, a collector cutoff current, a drain cutoff current, etc.) as in the first invention. By setting a larger value, the ON / OFF detection can be prevented from being affected by the leakage current at the time of OFF, which leads to the effect that "erroneous ON / OFF detection can be prevented".

The embodiment of the third invention shown in FIG. 29 combines the "on / off detection circuit symmetrical with respect to the voltage direction or voltage polarity with the on / off detection circuit of FIG. 5" and the current detection circuit of FIG. "Switching circuit with on / off detection function and main current detection function".

The embodiment of the third invention shown in FIG. 30 is a "switching circuit having an on / off detection function and a main current detection function" in which the on / off detection circuit of FIG. 2 and the current detection circuit of FIG. 14 are combined. .

The embodiment of the third invention shown in FIG. 31 is a "switching circuit having an on / off detection function and a main current detection function" in which the on / off detection circuit of FIG. 5 and the current detection circuit of FIG. 14 are combined. .

The embodiment of the third invention shown in FIG. 32 is a "switching circuit having an on / off detection function and a main current detection function" combining the on / off detection circuit of FIG. 4 and the current detection circuit of FIG. .

The embodiment of the third invention shown in FIG. 33 is a "switching circuit having an on / off detection function and a main current detection function" in which the on / off detection circuit of FIG. 7 and the current detection circuit of FIG. 14 are combined. .

The embodiment of the fourth invention shown in FIG.
And a switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function, which is a combination of the switching circuit of FIG. 28 and the embodiment of the third invention shown in FIG.
In the embodiment of FIG. 34, each corresponds to each of the above-described components as follows. a) The transistors 5 and 4 serve as the first and second switching means described above. b) The base terminal and the emitter terminal of the transistor 4 are the control terminal and the main terminal described above. c) Diode 10 is the non-controllable switching means described above. d) The diode 17 serves as the constant voltage means described above. e) "The series circuit of the DC power supply 1 and the resistors 12 and 13 connected to both ends of the transistor 5" is the current supply means described above. f) "Connector of transistor 43 and resistor 13"
Is the current detecting means described above. g) The "series circuit of the DC power supply 2 and the resistor 14 connected between the emitter and the base of the transistor 4" is the ON-direction driving means. h) "DC power supply 2,
The gate drive circuit formed by the transistor 4 (and the Zener diode 9) and the resistor 15 serves as the on / off drive means described above.

"DC power supply 2, resistor 14, transistor 4
And the main current detecting section constituted by the diode 17 (8) "
Is the main current of the embodiment of FIG. 34, that is, both terminals t62 and t63.
When the main current is larger than a predetermined value, the main current detector keeps the transistor 5 on through the gate drive circuit, and otherwise keeps the transistor 5 off. The embodiment of FIG. 34 is similar to the third embodiment of the embodiment of FIG.
Since the effect of the invention is inherited as it is and the current of the resistor 12 (on / off detection current) does not affect the detection of the main current, there is no problem even if the current of the resistor 12 is larger than the holding current value. "There is no need to pay attention to the on-off state caused by the on / off detection current (current of the resistor 12). 』
(Effects) Such effects exist in the switching circuit of the fourth invention including the embodiment of FIG.

The embodiment of the fourth invention shown in FIG.
This is a “switching circuit having an on / off detection function, a self-holding function, and a self-turn-off function” in which the switching circuit of FIG. 29 and the embodiment of the third invention shown in FIG. 29 are combined.

Finally, the following is supplemented. a) In the embodiment of FIG. 1, the diode 8 is used as a non-controllable switch, and the diode 8 detects that "overcurrent flows from the outside via the terminal t42, the emitter junction of the transistor 4, the switch 16 and the terminal t41". To stop or
This prevents "a current from the outside flowing to the transistor 3 through the terminal t42, the emitter junction of the transistor 4 and the resistor 12, and the current hindering the on / off detection". This is true for all aspects of the first invention. On the other hand, the diode 8 in each of the circuits shown in FIGS. 14, 15, 18 to 20, and the like is not necessarily used as a non-controllable switch, but is used as a voltage drop unit or a constant voltage unit. b) In the switching circuit of FIG. 39, while the switch 16 is on, a circuit (not shown) connected between the two terminals t53 and t54 applies a reverse voltage to the diode 11 and keeps it off. The ON / OFF detection current flows not through the diode 11 but through the circuit or the like. This is shown in FIG.
0, FIG. 41, FIG. 42, FIG. 44, FIG.

C) Both terminals t4 in the switching circuit of FIG.
If it is not convenient for a circuit or the like (not shown) connected between 1 and t42 to reversely flow current from the terminal 41 through the DC power supply 1, the resistors 13, 12 and the diode 10, and to flow to the terminal t42, FIG. Diode 7 shown in the switching circuit of
(6) is required. This is shown in FIGS.
The same applies to each switching circuit shown in FIG. In such a case, each of the switching circuits in FIGS. 39 to 42, 44, and 46 has an advantage that the number of components is smaller than each of the switching circuits in FIGS. 1, 36 to 38, 43, and 45. d) The resistor 12 in each of the embodiments shown in FIGS.
Alternatively, a constant current means including a constant current diode can be used instead of 14. e) Any type of switch can be used in each switching circuit, including a controllable switch instead of the mechanical switch 16.

F) Switching means having a self-turn-off function irrespective of a normally-on type or a normally-off type in place of each transistor 3 or 43 for current detection in each of the switching circuits of FIGS. 1 and 36 to 42. Anything can be used. For example, FET, MOS
FET, IGBT, SIT, GTO thyristor or SI
A thyristor or the like. g) It is not always necessary for the transistor 3 and the like to be completely turned on and off in accordance with the on and off of the switch 16, and the output state such as the on-resistance, the collector current, or the drain current turns the switch 16 on and off. It just needs to change accordingly. Therefore, for example, FIG.
42 to 43 may be biased in advance for the transistor 3 or 43. In short, it is only necessary to be able to detect whether a predetermined current is flowing through each resistor 12.

[0084]

2. Description of the Related Art (1) Technology related to ON / OFF detection circuit: a) JP-B-45-15088 b) JP-B-54-44489 c) JP-B-57-56307 (Thyristor 5l, transistor 5i and D) JP-A-50-99084 e) JP-A-58-81332 f) JP-A-62-5019 g) JP-A-63-302217 h) JP-A-1-117416 i) JP-A-2-1609 j) JP-A-2-146265 k) JP-A-60-93331 l) Japanese Patent Application No. 62-500831 (PCT / JP87 / 00053, WO 87/04575) m) Japanese Patent Application No. 62-504708 (PCT / JP87 / 00575, WO 88/01804) n) Japanese Patent Publication No. 52-50367 o) Japanese Patent Publication No. 54-9690 p) Japanese Patent Publication No. 57-6351 q) Japanese Patent Publication No. 59-44873

(2) Technology relating to a switching circuit having a self-holding function: a) JP-A-2-1609 b) JP-A-2-290326 c) JP-A-3-179815 (FIG. 7) d) JP-A-4 E) Japanese Utility Model Application Laid-Open No. 4-58083 f) Japanese Utility Model Application Laid-open No. 4-68492 g) Japanese Patent Application No. 62-504785 (PCT / JP87 / 00612, WO 88/01805)

(3) Technique relating to the drive circuit of the switching means: a) US Pat. No. 4,125,814 b) JP-A-62-147953 c) JP-A-2-153618 d) JP-A-3-69936 e) JP-A-3-69936 -80691 f) Japanese Utility Model Laid-open No. 3-82931

[0087]

[References related to terms] a) Semiconductor power conversion device (IEEE Technical Terminology No. 9) published by Corona Co. b) Semiconductor power conversion circuit (IEEE Semiconductor Power Conversion Method Research Special Committee Edition) Published by The Institute of Electrical Engineers of Japan

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the first invention.

FIGS. 2 to 13 are circuit diagrams each showing an example of a conventional on / off detection circuit.

FIGS. 14 to 19 are circuit diagrams each showing an example of a conventional current detection circuit.

20 to 21 are circuit diagrams each showing an example of a conventional switching circuit having a self-holding function and a self-turn-off function.

FIGS. 22 to 27 are circuit diagrams each showing an example of a switching circuit having an on / off detection function and a main current detection function, which is obtained by simply combining the conventional techniques.

28 to 33 are circuit diagrams each showing one embodiment of the third invention.

FIGS. 34 and 35 are circuit diagrams showing one embodiment of the fourth invention one by one.

36 to 42 are circuit diagrams showing one embodiment of the first invention one by one.

FIGS. 43 to 47 are circuit diagrams showing one embodiment of the second invention one by one.

FIGS. 48 to 49 are circuit diagrams each showing one embodiment of the first invention.

Continued on the front page (54) [Title of the Invention] "Switching circuit with on / off detection function and main current detection function", "Switching circuit with on / off detection function, self-holding function and self-turn-off function" "," Switching circuit with on / off detection function and main current detection function "and" switching circuit with on / off detection function, self-holding function and self-turn-off function "

Claims (4)

(57) [Claims] A first switching means driven on / off; a first non-controllable switching means connected in series with the first switching means in accordance with the controllable switching direction; Current supply means for supplying an on / off detection current to the first switching means when the first switching means is on without passing through the first non-controllable switching means; and detecting the on / off detection current And a forward bias direction between a control terminal and a main terminal forming a pair for inputting the drive signal and a forward direction of the first non-controllable switching means. A second switching means connected in series with the first non-controllable switching means, and a main current of the first switching means is supplied to the first non-controllable switching means. A second non-controllable switching means for guiding the voltage drop in a reverse bias direction between the control terminal and the main terminal to drive the second switching means in an off direction, A switching circuit having an on / off detection function and a main current detection function, comprising: an on-direction driving means for driving the second switching means in an on direction when no drop occurs. 2. A switching circuit having an on / off detection function and a main current detection function according to claim 1, wherein said switching circuit operates based on an output of said second switching means,
On / off driving means for driving the first switching means on when the second switching means is driven in the off direction, and for driving off the first switching means when not, Switching circuit with on / off detection function, self-hold function, and self-turn-off function. 3. A first switching means driven on and off, a non-controllable switching means connected in series with the first switching means in accordance with its controllable switching direction, An externally connected constant voltage means for generating a voltage drop in a constant voltage direction by flowing a main current of the first switching means; and the non-controllable switching means and the constant voltage when the first switching means is on. Current supply means for supplying an on / off detection current to the first switching means without any intervening voltage means; current detection means for detecting the on / off detection current; and a pair for inputting a drive signal thereof. A second switching means for supplying a drive signal in the OFF direction based on the voltage drop between the control terminal and the main terminal, and the drive signal is not supplied A switching circuit having an on / off detection function and a main current detection function, comprising: an on-direction driving means for driving the second switching means in an on direction. 4. A switching circuit having an on / off detection function and a main current detection function according to claim 3, wherein the switching circuit operates based on an output of the second switching means,
On / off driving means for driving the first switching means on when the second switching means is driven in the off direction, and for driving off the first switching means when not, Switching circuit with on / off detection function, self-hold function, and self-turn-off function.