JP7200528B2 - current breaker - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current circuit breaker, and more particularly to a current circuit breaker with a compound semiconductor switch configuration that employs semiconductor switching elements.

As a current breaker that protects a circuit from an abnormality such as a short circuit, a mechanical switch is known as the simplest structure. However, in the case of a mechanical switch, due to the reaction speed of a mechanism such as a spring, arcing may occur when current is interrupted, and a short-circuit current will flow through the arcing. As a countermeasure, a current breaker that employs a configuration in which a semiconductor switch is connected in parallel with a mechanical switch is known (see, for example, Patent Document 1).

In the case of a configuration in which semiconductor switches are connected in parallel, arcing is prevented from occurring in the mechanical switch by commutating the current to the side of the semiconductor switches connected in parallel during the current interruption operation. However, in the case of this configuration, it is necessary to follow the order of turning off the mechanical switch and then turning off the semiconductor switch, so it takes a relatively long time to cut off the current.

Therefore, a configuration is known in which a plurality of semiconductor elements are connected in parallel, and one element is responsible for switching and the other element is responsible for reducing the current conduction loss during normal operation. With respect to this type of configuration, a technique has been proposed in which a semiconductor element with a low withstand voltage but capable of high-speed switching is arranged, and the current conduction path is switched to one element or the other element by turning the semiconductor element on or off. (for example, Patent Document 2). In addition, thyristors and triacs, which have relatively large current capacities and relatively small current conduction losses, are adopted as elements that play a role in reducing current conduction losses during steady-state operation. There have also been proposals for current applications (see, for example, Patent Documents 3 to 6).

Japanese Patent No. 5628184 JP 2011-135758 A JP 2005-192354 A JP-A-2006-50697 JP-A-2008-54468 Japanese Patent Application Laid-Open No. 2009-81969

Regarding the configuration employing a plurality of semiconductor switching elements, for example, in the configuration described in Patent Document 6, the current flows through the two semiconductor switching elements, the IGBT and the MOSFET, so the current conduction loss is equivalent to that of the two semiconductor switching elements. Furthermore, there has been a desire to reduce current conduction loss. As a general characteristic of semiconductor switching elements, there is a trade-off relationship between switching speed and on-resistance. Therefore, if a semiconductor switching element having a high switching speed is used, for example, the switching loss can be reduced, but the on-resistance is increased, so the current conduction loss is increased. In other words, in the prior art, it was difficult to achieve both high-speed current interruption and reduction in current conduction loss.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a current breaker capable of interrupting current at high speed and reducing current conduction loss.

In order to achieve the above object, a current circuit breaker according to one aspect of the present invention is a current circuit breaker comprising a main conducting section which is a current conducting section and an auxiliary conducting section connected in parallel to the main conducting section. wherein the main conduction portion is connected in series with a first semiconductor switching element having no self arc-extinguishing function, and the first semiconductor switching element, and provides conduction for switching the conduction portion by ON/OFF operation. a section switching element, wherein the auxiliary conduction section is formed by a second semiconductor switching element, the first semiconductor switching element, the conduction section switching element, and the second semiconductor switching element; and a control circuit for respectively controlling the on and off operations of the.

Further, in order to achieve the above object, a current circuit breaker according to another aspect of the present invention is a current circuit breaker comprising a main conduction section which is a current conduction section and an auxiliary conduction section connected in parallel to the main conduction section. A circuit breaker, wherein the main conducting section includes a series circuit including a first semiconductor switching element having no self-extinguishing function and a conducting section switching element connected in anti-parallel to each other; A parallel circuit in which a diode is connected in anti-parallel to two semiconductor switching elements is connected in anti-series to each other to form a bidirectional conduction path, wherein the first semiconductor switching element, the conducting part switching element, and the and a control circuit for controlling ON and OFF operations of the second semiconductor switching element.

In the above configuration, for example, the first semiconductor switching element has a larger current capacity and higher conductivity than the second semiconductor switching element, and the second semiconductor switching element has a higher current capacity than the first semiconductor switching element. High-speed switching operation is also possible. Since the current mainly flows through the first semiconductor switching element, conduction loss can be reduced. When the current is cut off, the conduction portion switching element is turned off first, thereby facilitating the turn-off operation of the first semiconductor switching element, and the main conduction portion quickly becomes non-conducting. In this case, the current flows through the auxiliary conductive portion formed by the second semiconductor switching element, but since the second semiconductor switching element is also a switching element that can be turned off at a relatively high speed, the current breaker as a whole can be turned off at high speed. Current can be interrupted. Further, according to the connection relationship and operation of each semiconductor element as described above, the switching loss due to the conductive portion switching element and the second semiconductor switching element capable of high-speed switching operation is relatively small, so that the switching loss can be reduced.

According to the technique of the present disclosure, it is possible to provide a current circuit breaker that can interrupt current at high speed and reduce current conduction loss.

1 is a circuit diagram showing a main configuration of a composite semiconductor switch according to a first embodiment of the invention; FIG. 1 is a circuit diagram showing the overall configuration of a composite semiconductor switch according to a first embodiment of the invention; FIG. FIG. 4 is a waveform diagram for explaining the operation of the composite semiconductor switch according to the first embodiment of the invention; FIG. 4 is a schematic diagram for explaining the operation of the composite semiconductor switch according to the first embodiment of the invention; FIG. 10 is a circuit diagram showing a main configuration of a composite semiconductor switch according to a second embodiment of the invention; FIG. 10 is a waveform diagram for explaining the operation of the composite semiconductor switch according to the second embodiment of the invention; FIG. 9 is a schematic diagram for explaining the operation of the composite semiconductor switch according to the second embodiment of the invention; FIG. 10 is a circuit diagram showing a main configuration of a composite semiconductor switch according to a third embodiment of the invention; FIG. 11 is a drive voltage waveform diagram for explaining the operation of the composite semiconductor switch according to the third embodiment of the invention; FIG. 10 is a waveform diagram for explaining the operation of the composite semiconductor switch according to the third embodiment of the invention;

Hereinafter, current circuit breakers according to embodiments of the present invention will be described in detail with reference to the drawings. One of the features of the present invention is that it employs a circuit configuration that enables high-speed current interruption and reduction of current conduction loss.

(First embodiment)
First, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4. FIG. The configuration according to this embodiment will be described with reference to FIGS. 1 and 2, and the operation according to this embodiment will be described with reference to FIGS. 3 and 4. FIG.

(Constitution)
As shown in FIGS. 1 and 2, the current circuit breaker according to the present embodiment is, for example, a composite semiconductor switch 10 applied to a switchboard in a factory or the like, and includes a first semiconductor switching element 1 and a conducting part switching It comprises an element 2 , a second semiconductor switching element 3 and a control circuit 4 .

The first semiconductor switching element 1 is a semiconductor switching element having a relatively low on-resistance and a relatively small current conduction loss, and in this embodiment, it is composed of a separately-excited thyristor. Hereinafter, the first semiconductor switching element 1 is referred to as a thyristor 1 for convenience of explanation. Further, the conducting portion switching element 2 is appropriately referred to as MOSFET 2 . The thyristor 1 has an anode connected to the input terminal IN of the composite semiconductor switch 10 , a cathode connected to the drain of the MOSFET 2 , and a gate connected to the control circuit 4 .

The conducting portion switching element 2 is a semiconductor switching element having a higher switching speed than the first and second semiconductor switching elements. In the present embodiment, the conduction part switching element 2 is, for example, a low-voltage MOSFET with an on-resistance of several milliohms when the withstand voltage is several tens of volts, and has a built-in body diode or a diode connected in anti-parallel. . The MOSFET 2 has a source connected to the output terminal OUT of the composite semiconductor switch 10 and a gate connected to the control circuit 4 . That is, the MOSFET 2 is arranged and connected to the cathode side of the thyristor 1 . A series circuit is formed by the thyristor 1 and the MOSFET 2 , and this series circuit forms the main conducting portion 11 in the composite semiconductor switch 10 . The MOSFET 2 is an element for switching current paths in the composite semiconductor switch 10, and details of its operation will be described later.

The second semiconductor switching element 3 is a semiconductor switching element whose switching speed is higher than that of the thyristor 1 . Since high-speed switching operation is possible, the second semiconductor switching element 3 can be composed of a semiconductor switching element with relatively low switching loss, and is composed of an IGBT in this embodiment. Hereinafter, the 2nd semiconductor switching element 3 is called IGBT3 for convenience of explanation. The IGBT 3 has a collector connected to the input terminal IN of the composite semiconductor switch 10 and an emitter connected to the output terminal OUT of the composite semiconductor switch 10 . That is, the IGBT 3 is connected in parallel with the series circuit of the thyristor 1 and the MOSFET 2 to form the auxiliary conducting portion 12 in the composite semiconductor switch 10 . The gate of IGBT 3 is also connected to control circuit 4 . The IGBT 3 is an element for finally interrupting current by high-speed switching operation, and the details of its operation will be described later.

To summarize the relationship between the thyristor 1 and the IGBT 3 with respect to switching speed and on-resistance, the thyristor 1, which has a low on-resistance, a small current conduction loss, and a large current capacity, plays a role in steady-state conduction. On the other hand, as for the switching operation, the IGBT 3, which is capable of high-speed switching operation and has small switching loss, plays a role. The MOSFET 2, which is the fastest among these elements, plays the role of switching the current path, that is, switching of the division of roles.

Next, the control circuit 4 will be explained. The control circuit 4 is a circuit for controlling the timing of applying a voltage to the gate of each semiconductor element (thyristor 1, MOSFET 2, IGBT 3) in the composite semiconductor switch 10. In this embodiment, the protection circuit 41 and gate pulse distribution A circuit 42 and a drive circuit 43 are provided.

The protection circuit 41 receives a control signal (ON/OFF control signal) from the external control device 5 via the control terminal CTL of the composite semiconductor switch 10 . The protection circuit 41 detects the current on the input terminal IN side of the composite semiconductor switch 10, and supplies a control signal to the next-stage gate pulse distribution circuit 42 when the value of this current is equal to or greater than a predetermined overcurrent set value lim. to stop.

The gate pulse distribution circuit 42 gives predetermined delay times td _on , td _off and a time difference ΔT to the control signal given via the protection circuit 41, thereby shifting the ON/OFF operation timing of each semiconductor switching element. . The delay times td _on and td _off and the time difference ΔT will be described later.

The drive circuit 43 applies a voltage to the gate of each semiconductor element at a timing corresponding to the delay time td- _on or the like given to the control signal in the gate pulse distribution circuit 42 .

Regarding the details of the configuration of the protection circuit 41, the gate pulse distribution circuit 42, and the drive circuit 43, any configuration can be used as long as the operation described with reference to FIG. 3 can be realized. A circuit configuration can be adopted.

In this embodiment, the thyristor 1, the MOSFET 2, the IGBT 3, and the control circuit 4 are packaged as one power module and arranged on a switchboard or the like. It operates by being supplied to the control terminal CTL, but is not limited to this.

(motion)
Next, the current interrupting operation of the composite semiconductor switch 10 employing the above configuration will be described in detail with reference to FIGS. 3 and 4. FIG.

As shown in (I) of FIGS. 3 and 4, first, with the thyristor 1, the MOSFET 2 and the IGBT 3 turned off, a voltage is applied from the control circuit 4 to the gate of the IGBT 3, and only the IGBT 3 is turned on at timing t1. . Since the IGBT 3 is a semiconductor switching element capable of switching operation at a relatively high speed, it can quickly turn on. Turning on the IGBT 3 capable of high-speed switching operation first contributes to speeding up the start-up operation of the composite semiconductor switch 10 as a whole. In this case, since only the IGBT 3 is on, only the auxiliary conducting portion 12 is conducting, and therefore the current flows through the auxiliary conducting portion 12 .

Next, as shown in FIGS. 3 and 4(II), a voltage is applied from the control circuit 4 to the gates of the thyristor 1 and the MOSFET 2 after a delay time td _on after the voltage is applied to the gate of the IGBT 3. thyristor 1 and MOSFET 2 are turned on at timing t2. In this case, since the thyristor 1 has a lower on-resistance and a higher conductivity than the IGBT 3, most of the current from the input terminal IN of the composite semiconductor switch 10 is the thyristor 1 on the side with higher conductivity, that is, , to flow through the main conduction portion 11 . It should be noted that the delay time td-on only needs to secure the time required for turning _on the IGBT 3, that is, the time from the completion of the turn-on operation until the steady-state current is supplied. Specifically, it is about 1 μs to 2 μs, but it is not limited to this. By turning on the IGBT 3 first in this manner, the turn-on loss of the thyristor 1 does not occur.

In FIG. 3, the control circuit 4 simultaneously applies to both gates the gate drive voltage for turning on the thyristor 1 and the MOSFET 2 at the timing t2 after the delay time td _on . It is not necessary to apply to both gates. For example, as shown in (I) of FIG. 9 for explaining the operation of the embodiment described later, the control circuit 4 applies a gate drive voltage to turn on the MOSFET 2 at timing t2 after the delay time td _on , and then , a gate drive voltage for turning on the thyristor 1 may be applied. In this embodiment, the turn-on speed of MOSFET 2 is faster than that of thyristor 1. Therefore, the turn-on loss of thyristor 1 can be suppressed as compared with the case where thyristor 1 is turned on after the delay time td _on and then MOSFET 2 is turned on. can. Note that FIG. 9 will be described later.

Here, the inventors performed a simulation on the ratio of the currents flowing through the main conductive portion 11 and the auxiliary conductive portion 12 . For example, when semiconductor switching elements are compared under conditions of a rated voltage of 1200 V and 50 A, the thyristor 1 has an ON voltage of 1.4 V and an ON resistance of approximately 28 milliohms. On the other hand, the IGBT 3 has an ON voltage of 1.8 V and an ON resistance of approximately 36 milliohms. The adopted MOSFET 2 has an on-resistance of 1 milliohm or less, and since the on-resistance of the main conducting portion 11 is lower than that of the auxiliary conducting portion 12, current tends to flow to the on-resistance side (main conducting portion 11 side). That is, since the ratio of the currents flowing through the main conductive portion 11 and the auxiliary conductive portion 12 is obtained according to the ratio of the on-resistance, this ratio can be set to a suitable value by appropriately selecting the number of parallel elements. It is possible. For example, it is possible to set the on-resistance ratio to a desired and appropriate value with respect to the auxiliary conducting portion 12 by arranging appropriately selected elements in parallel on the main conducting portion 11 side. Alternatively, for example, on the side of the auxiliary conducting portion 12, it is conceivable to use the trade-off relationship between the switching speed and the on-resistance to select an element to which the switching speed is preferentially applied, thereby intentionally increasing the on-resistance. .

Returning to the description of the current interruption operation. Subsequently, as shown in (III) of FIGS. 3 and 4, application of voltage from the control circuit 4 to the gate of the MOSFET 2 is stopped (that is, the gate is turned off) to turn it off at timing t3. Since the MOSFET 2 can be turned off in, for example, several tens of ns as described above, it quickly becomes non-conducting after the voltage application to the gate is stopped.

At this stage, the thyristor 1 is still conducting between the anode and the cathode and is not turned off (extinguishing the arc). Once the separately excited thyristor 1 is ignited (conducted), it cannot be extinguished simply by stopping the application of voltage to the gate. However, in this embodiment, MOSFET 2 is turned off first, so the potential difference between the terminals of MOSFET 2 causes a reverse bias between the anode and cathode of thyristor 1 . That is, the MOSFET 2 becomes non-conductive first, so that a voltage (reverse bias) is applied between the anode and the cathode of the thyristor 1 so that the potential on the cathode side is higher than that on the anode side. This reverse bias allows the charge of the thyristor 1 to be drawn from the anode. Then, in the state where the charge of the thyristor 1 is pulled out from the anode, the voltage application to the gate of the thyristor 1 is stopped after a time difference ΔT after the voltage application to the gate of the MOSFET 2 is stopped (that is, the gate is turned off). do). As a result, the thyristor 1 is extinguished at timing t4 to be in a non-conducting state.

At timing t4, the thyristor 1 and the MOSFET 2 are in a non-conducting state, so the main conducting portion 11 is completely cut off and current flows through the auxiliary conducting portion 12. FIG. In the auxiliary conducting section 12, the IGBT 3 is on, and in order to cut off the current, the application of voltage from the control circuit 4 to the gate of the IGBT 3 is stopped after a delay time td _off after turning off the low-voltage MOSFET 2 at timing t3. It is stopped and turned off at timing t5. Since the IGBT 3 is a semiconductor switching element capable of switching at a relatively high speed, it quickly becomes non-conducting. As a result, the auxiliary conductive portion 12 is also cut off, and thus the operation of cutting off the current in the entire composite semiconductor switch 10 is completed.

(Action)
As described above, according to the configuration according to the present embodiment, it is possible to reduce the current conduction loss. Specifically, the MOSFET 2 has an on-resistance of several milliohms in the case of a rating of several tens of volts, and the IGBT 3 is capable of switching at high speed, and the auxiliary conductive portion 12 becomes non-conductive in an extremely short time. Therefore, the current conduction loss can be considered as one thyristor 1 (first semiconductor switching element) in the main conducting portion 11 without substantially considering the current conduction loss in the MOSFET 2 and the IGBT 3 . Therefore, the current conduction loss in the entire composite semiconductor switch 10 is small compared to, for example, the prior art in which a plurality of semiconductor switching elements form a series circuit.

Further, according to the configuration according to the present embodiment, it is possible to cut off the current at high speed. Specifically, in the above example, the MOSFET 2 can be turned off in several 10 ns, and for the thyristor 1, the reverse bias is applied by the non-conducting MOSFET 2, and the timing of applying the voltage to the gate from the control circuit 4 can be set appropriately, the arc can be quickly extinguished. Since the IGBT 3 is a semiconductor switching element capable of relatively high-speed switching operation, by appropriately setting the timing of stopping the application of the voltage to the gate of the IGBT 3 after extinguishing the thyristor 1, It can be in a conducting state. Therefore, the composite semiconductor switch 10 as a whole can interrupt the current at high speed.

In the current interrupting operation, the auxiliary conducting portion 12 side needs only a short time for the current to be conducted. For example, considering the switching speed described in the data sheet under the above simulation conditions, the delay time td _on from turning on the IGBT 3 to turning on the thyristor 1 (and the low-voltage MOSFET 2) is from 1 μs to It is about 2 microseconds. As for the IGBT 3, it is sufficient to consider only short-time conduction, so that the size and cost of the device can be reduced.

Furthermore, according to the configuration of the present embodiment, it is possible to prevent the erroneous turn-on phenomenon due to the influence of the residual electric charges in the thyristor 1, which does not have a self-extinguishing function.

This point will be described in detail. In principle, in a thyristor without a self-extinguishing function, once a voltage is applied to the gate to cause ignition (conduction), even if the voltage application to the gate is stopped, the ignition (conduction) state remains. is maintained. Regarding this point, the present inventors conducted various verifications in relation to the above configuration. Even if the thyristor in the ignition state (the thyristor 1 in the above configuration) is not conducting current, the voltage at the turn-off of the parallel-connected IGBTs 3 is An event applied to one cycle of the anode of the thyristor 1-cathode-low voltage MOSFET 2 was found. It has been found that when this event occurs, the thyristor 1 may begin conducting current again. Hereinafter, such a phenomenon of the thyristor 1 is referred to as an erroneous turn-on phenomenon in this specification.

The inventors of the present invention conducted various tests to further verify the results, and obtained the following findings regarding the avoidance of the erroneous turn-on phenomenon. First, by turning off the MOSFET 2 connected in series before the thyristor 1, the potential difference generated between the terminals of the MOSFET 2 is applied to the thyristor 1 as a reverse bias. However, there are cases where this reverse bias is not large enough to pull out the charge between the anode and cathode of the thyristor 1 . If the voltage application to the gate of the thyristor 1 is not stopped while a reverse bias that is not large enough to pull out the charge between the anode and the cathode of the thyristor 1 is applied, the thyristor 1 is erroneously turned on. The inventors have found that the phenomenon can occur. Therefore, in the present invention, a time difference ΔT is provided from when the MOSFET 2 is turned off, that is, when the voltage application to the gate of the MOSFET 2 is stopped until the voltage application to the gate of the thyristor 1 is stopped. If .DELTA.T is too short, the above-mentioned reverse bias will not be large enough to pull out the thyristor 1 charge. On the other hand, if ΔT is too long, the current cannot be interrupted at high speed. Considering these factors, ΔT should be appropriately set according to various conditions such as specifications in actual use so that a reverse bias sufficient to pull out the charge of the thyristor 1 can be obtained. Therefore, a configuration in which ΔT can be set in the gate pulse distribution circuit 42 from the outside may be adopted. Alternatively, if the various conditions in the actual application can be grasped in advance and the suitable value of ΔT can be grasped in advance, a configuration in which the gate pulse distribution circuit 42 holds the suitable value of ΔT is employed. may

Therefore, according to the configuration of the present embodiment, even in a configuration using the thyristor 1 that does not have a self-extinguishing function, the erroneous turn-on phenomenon of the thyristor 1 during the current interruption operation can be prevented with a relatively simple circuit configuration. As a result, the operation of the composite semiconductor switch 10 can be stabilized.

(Second embodiment)
In the first embodiment, the case where the current cut off by the composite semiconductor switch 10 is a direct current flowing from the input terminal IN to the output terminal OUT has been described. However, in actual applications, there may be a need to apply the composite semiconductor switch 10 of the present invention to switchboards that handle alternating current, for example. In such a case, it is preferable to employ a configuration in which a plurality of main conductive portions 11 are provided so that both positive and negative polarities can be handled. The composite semiconductor switch 10 having such a configuration will be described in detail below. Components similar to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

(Constitution)
As shown in FIG. 5, the composite semiconductor switch 10 according to this embodiment includes thyristors 1 and 1a, MOSFETs 2 and 2a, and IGBTs 3 and 3a. The composite semiconductor switch 10 also includes a control circuit 4 (not shown) as in the first embodiment, and this control circuit 4 is connected to an external control device 5 (not shown). As for the control circuit 4 and the control device 5, similar to the first embodiment, known techniques can be applied, so the description thereof will be omitted below. Further, the composite semiconductor switch 10 has a first terminal A and a second terminal B instead of the input terminal IN and the output terminal OUT of the first embodiment.

A thyristor 1 and a MOSFET 2 are the same as those in the first embodiment, and form a first main conducting portion 11 in this embodiment. The thyristor 1a and the MOSFET 2a form a second main conduction portion 11a, and more specifically, are connected in anti-parallel to the first main conduction portion 11, and the direction of current flow is opposite. A certain second main conductive portion 11a is formed.

In this manner, the main conducting section according to the second embodiment has a pair of series circuits connected in anti-parallel to each other. Of the pair of series circuits, the first series circuit including the structure in which the thyristor 1 and the MOSFET 2 are connected in series forms the first main conducting portion 11, and the thyristor 1a and the MOSFET 2a are connected in series. A second series circuit comprising a configuration forms a second main conducting portion 11a.

The IGBT 3 and the IGBT 3a are connected in series to form an auxiliary conducting portion 12. FIG. The auxiliary conducting portion 12 is connected in parallel to the first main conducting portion 11 and the second main conducting portion 11a. In the present embodiment, since current flows bidirectionally, IGBTs in which diodes are connected in anti-parallel, for example, are employed as the IGBTs 3 and 3a. In this case, the collector of the IGBT 3 and the collector of the IGBT 3a are connected to each other, the emitter of the IGBT 3 is connected to the second terminal B, and the emitter of the IGBT 3a is connected to the first terminal A. Each diode is connected from the emitter of each IGBT 3, 3a toward the collector.

The first terminal A is provided between the end of the first main conducting portion 11 and the second main conducting portion 11a on the side of the thyristor 1 and the MOSFET 2a and the end of the auxiliary conducting portion 12 on the side of the IGBT 3a. The second terminal B is provided between the MOSFET 2 and thyristor 1a side ends of the first main conducting portion 11 and the second main conducting portion 11 a and the IGBT 3 side end of the auxiliary conducting portion 12 . Hereinafter, in order to facilitate understanding of the present invention, the case where the current flows from the first terminal A to the second terminal B is positive, and the current flows from the second terminal B to the first terminal A. The case where the current flows is described as the negative polarity.

(motion)
Next, the current interrupting operation of the composite semiconductor switch 10 employing the above configuration will be described in detail with reference to FIGS. 6 and 7. FIG. In the following description, a representative example of the current interruption operation performed when the current has a positive polarity will be described.

First, as shown in (I) of FIGS. 6 and 7, a voltage is applied to the gate of the IGBT 3 to turn it on at timing t1. In this case, current flows from the first terminal A to the second terminal B through the diode of IGBT 3a and IGBT3.

_Next , in order to cause current to flow through the first main conduction portion 11, as shown in (II) of FIGS. is turned on at timing t2 by applying a voltage to the gate of . As a result, the first main conduction portion 11 becomes conductive, and most of the current flows through the first main conduction portion 11 . Here, it is arbitrary whether or not to turn on the thyristor 1a and the low-voltage MOSFET 2a by applying a voltage to the gate. However, the direction of current flow is designed to be opposite between the first main conducting portion 11 and the second main conducting portion 11a. Therefore, when the thyristor 1a and the low-voltage MOSFET 2a are turned on in the same manner as the thyristor 1 and the low-voltage MOSFET 2, for example, when a large reverse current is applied, the low-voltage MOSFET 2a and the thyristor 1a may break down. Therefore, it is preferable to employ control that does not turn on the thyristor 1a and the low-voltage MOSFET 2a.

Next, as shown in (III) of FIGS. 6 and 7, before the thyristor 1 is turned off, the voltage application to the gate of the MOSFET 2 is stopped to turn it off at timing t3. The reason why the MOSFET 2 is turned off before the thyristor 1 is to apply a sufficient reverse bias to draw out the charge of the thyristor 1, as in the first embodiment.

Subsequently, after a time difference ΔT from when the voltage application to the gate of the MOSFET 2 is stopped, the voltage application to the gate of the thyristor 1 is stopped and the arc is extinguished at the timing t4. The thyristor 1 is discharged from the thyristor 1 after the time difference .DELTA.T due to the applied reverse bias, so that the erroneous turn-on phenomenon can be prevented in the same manner as in the first embodiment.

Since the first main conducting portion 11 is rendered non-conducting, current flows through the auxiliary conducting portion 12 as shown in (III) of FIGS. 6 and 7 . Therefore, td _off after stopping the voltage application to the gate of the low withstand voltage MOSFET 2, the voltage application to the gate of the IGBT 3 is stopped and the IGBT 3 is turned off at the timing t5. As a result, even if the current flowing from the first terminal A to the second terminal B passes through the diode connected in antiparallel to the IGBT 3a, the current reaches the second terminal B because the IGBT 3 is off. do not do. Accordingly, the entire composite semiconductor switch 10 completes the operation of interrupting the current.

When the current flows from the second terminal B to the first terminal A, that is, when the current has a negative polarity, the on/off operations of the MOSFET 2a, the thyristor 1a and the IGBT 3a are controlled in the same order as the above control. do it.

(Third Embodiment)
FIG. 8 is a circuit diagram showing the main configuration of composite semiconductor switch 10 according to the third embodiment. The same reference numerals are given to the same components as in the above-described embodiment, and detailed description thereof will be omitted.

A composite semiconductor switch 10 according to the present embodiment includes a thyristor 1, a MOSFET 2, an IGBT 3, and a pulse voltage output source 44. The composite semiconductor switch 10 also includes a control circuit 4 (not shown) as in the first embodiment, and this control circuit 4 is connected to an external control device 5 (not shown). As for the control circuit 4 and the control device 5, similar to the first embodiment, known techniques can be applied, so the description thereof will be omitted below.

A pulse voltage output source 44 is provided in the drive circuit 43 of the control circuit 4 . The output timing of the pulse voltage (hereinafter also referred to as pulse voltage _VAUX ) output from the pulse voltage output source 44 with a predetermined time width is switched according to the control signal from the gate pulse distribution circuit 42 . The pulse voltage output source 44 applies the pulse voltage _VAUX to the cathode K side of the thyristor 1 for a predetermined time at a timing corresponding to the delay time given to the control signal in the gate pulse distribution circuit 42 . In this embodiment, the pulse voltage output source 44 applies to the cathode K side a pulse voltage _VAUX that makes the potential on the cathode K side of the thyristor 1 higher than the potential on the anode A side. For example, the pulse voltage output source 44 applies a pulse voltage VAUX, which is a positive voltage with respect to the source S of the _MOSFET2 , between the source S and the drain D of the MOSFET2.

The control circuit 4 outputs the pulse voltage V _AUX from the pulse voltage output source 44 after turning off the gate of the MOSFET 2 with the IGBT 3 turned on and before turning off the gate of the IGBT 3 . The control circuit 4 generates a reverse bias between the anode and the cathode of the thyristor 1 by causing the pulse voltage V _AUX to be output from the pulse voltage output source 44 while maintaining the conduction of the auxiliary conduction portion 12 by the ON state of the IGBT 3. can be made As a result, the residual carriers in the thyristor 1 can be extracted from the anode A of the thyristor 1 more quickly than when the pulse voltage V _AUX is not applied, so that the erroneous turn-on phenomenon caused by the influence of the residual carriers can be effectively prevented. can. Therefore, it is possible to realize a stable cut-off operation of the thyristor 1 that does not have a self-extinguishing function.

The control circuit 4 outputs the pulse voltage V _AUX from the pulse voltage output source 44 during the period from when the gate of the MOSFET 2 is turned off with the IGBT 3 turned on and then the gate of the thyristor 1 is turned off until the gate of the IGBT 3 is turned off. You may let The control circuit 4 generates a reverse bias between the anode and the cathode of the thyristor 1 by causing the pulse voltage V _AUX to be output from the pulse voltage output source 44 while maintaining the conduction of the auxiliary conduction portion 12 by the ON state of the IGBT 3. can be made By turning off the gate of the MOSFET 2 before the gate of the thyristor 1 is turned off, the reverse bias applied between the anode and the cathode of the thyristor 1 can be made sufficiently large, so that the residual carriers of the thyristor 1 can be removed from the anode of the thyristor 1 more quickly. can be pulled out. Therefore, the erroneous turn-on phenomenon due to the influence of residual carriers can be prevented more effectively, and the stable cutoff operation of the thyristor 1, which does not have a self-extinguishing function, can be realized.

FIG. 9 is a drive voltage waveform diagram for explaining the operation of the composite semiconductor switch according to the third embodiment of the invention. FIG. 10 is a waveform diagram for explaining the operation of the composite semiconductor switch according to the third embodiment of the invention.

In section (I), first, the control circuit 4 applies a gate drive voltage _VGE between the gate and the emitter E to turn on the gate of the IGBT 3 while the thyristor 1, the MOSFET 2 and the IGBT 3 are turned off. As a result, the current IQ1 flows from the input terminal IN to the output terminal OUT via the collector C of the _IGBT3 . By turning on the IGBT 3, the voltage V _AK between the anode A and the cathode K of the thyristor 1 is lowered.

Next, in intervals (I) and (II), the control circuit 4 applies a gate drive voltage to turn on the thyristor 1 after applying a gate drive voltage to turn on the MOSFET 2 at a timing after the delay time td- _on . Since the turn-on speed of the MOSFET 2 is faster than that of the thyristor 1, the turn-on loss of the thyristor 1 can be suppressed as compared with the case where the thyristor 1 is turned on after the delay time td _on and then the MOSFET 2 is turned on. In the interval (II), the current flowing through the composite semiconductor _switch 10 is divided between the main conducting portion 11 and the auxiliary conducting portion 12, the current _IQ1 flowing through the main conducting portion 11, and the current IQ2 flowing through the auxiliary conducting portion 12. flows.

In the section (III), the control circuit 4 applies a reverse bias to the thyristor 1 by turning off the application of the gate voltage of the MOSFET 2, and then turns off the gate of the thyristor 1, thereby making the main conduction portion 11 conductive. block the As a result, only the current _IQ1 flows again, and the current _IQ2 flowing through the auxiliary conductive portion 12 is cut off.

In the section (IV), the control circuit 4 turns on the pulse voltage output source 44 while maintaining the ON state of the IGBT 3, and applies the pulse voltage V _AUX to the thyristor 1 to apply a reverse bias across the anode and cathode of the thyristor 1. is applied to the cathode side of the for a predetermined time. During the application period of the pulse voltage V _AUX , the drain-source voltage V _DS of the MOSFET 2 increases, and the voltage V _AK between the anode A and the cathode K of the thyristor 1 becomes a negative voltage due to the reverse bias. After applying the pulse voltage V _AUX with a predetermined time width, the control circuit 4 turns off the pulse voltage output source 44 to stop applying the pulse voltage V _AUX .

In the section (V), the control circuit 4 turns off the gate of the IGBT 3 , thereby interrupting the conduction of the auxiliary conduction part 12 and interrupting the entire conduction of the composite semiconductor switch 10 .

As described above, according to the present embodiment, even when the current to be interrupted is alternating current, the same effects and effects as those of the first embodiment can be obtained.

(Other embodiments)
The present invention is not limited to the above embodiments, and various modifications and applications are possible. For example, in the above embodiments, the case where the second semiconductor switching element is an IGBT has been described as an example. However, power MOSFETs may be used instead of IGBTs, for example, in applications requiring faster switching speeds than with IGBTs but with lower breakdown voltages. In this case, by connecting the MOSFET to the auxiliary conductive section 12 so that current flows from the source to the drain of the MOSFET, it is expected that the current conduction loss can be further reduced by the so-called synchronous rectification effect.

In the second embodiment, the second semiconductor switching elements 3 and 3a are respectively IGBTs in which diodes are connected in anti-parallel. IGBT) may be used. In this case, in the second embodiment, the IGBTs 3 and 3a are connected in anti-series, but by connecting the RB-IGBTs in anti-parallel, it is possible to obtain the same action and effect.

Furthermore, by adopting a semiconductor switching element formed of a wide bandgap material such as silicon carbide as the second semiconductor switching element, and adopting a high voltage thyristor or the like as the thyristor 1, comparison with the embodiment can be achieved. As a result, a higher withstand voltage can be obtained, making it possible to handle applications in which a larger current flows.

Furthermore, in the above embodiment, the case where the first semiconductor switching element 1 is a thyristor that does not have a self-extinguishing function has been described as an example, but a GTO thyristor, for example, may be employed. In this case, the GTO thyristor is theoretically capable of firing and extinguishing according to the application of voltage to the gate. By applying a bias, an effect of helping the turn-off operation of the GTO thyristor can be expected.

Although the current circuit breaker has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements such as combination or replacement with part or all of other embodiments are possible within the scope of the present invention.

For example, another element such as a resistor may be connected in series to the thyristor 1 or the MOSFET 2, another element such as a resistor may be connected in series to the thyristor 1a or the MOSFET 2a, and a resistor or the like may be connected to the IGBT 3 or the IGBT 3a. may be connected in series.

1, 1a thyristor (first semiconductor switching element)
2, 2a MOSFET (conducting part switching element)
3, 3a IGBT (second semiconductor switching element)
4 control circuit 5 control device 10 composite semiconductor switch (current breaker)
11, 11a main conductive portion 12, 12a auxiliary conductive portion 41 protection circuit 42 gate pulse distribution circuit 43 drive circuit A first terminal B second terminal IN input terminal OUT output terminal CTL control terminal

Claims (7)

A current circuit breaker comprising a main conduction part that is a current conduction part and an auxiliary conduction part connected in parallel to the main conduction part,
The main conduction portion includes a first semiconductor switching element having no self arc-extinguishing function, and a conduction portion switching element connected in series with the first semiconductor switching element for switching the conduction portion by an on/off operation. , formed by
the auxiliary conduction part is formed by a second semiconductor switching element,
a control circuit for controlling ON/OFF operations of the first semiconductor switching element, the conducting portion switching element, and the second semiconductor switching element;
with
The control circuit cuts off the main conduction portion by controlling the conduction portion switching element and the first semiconductor switching element in that order, and cuts off the main conduction portion by controlling the second semiconductor switching element. A current breaker that applies a reverse bias to the first semiconductor switching element by turning off the gate of the conduction part switching element in the ON state of . A current circuit breaker comprising a main conduction part that is a current conduction part and an auxiliary conduction part connected in parallel to the main conduction part,
The main conduction section has a pair of series circuits each including a configuration in which a first semiconductor switching element having no self-extinguishing function and a conduction section switching element are connected in series, and the pair of series circuits are connected to each other. connected in anti-parallel,
the auxiliary conducting portion is formed by connecting a pair of parallel circuits in which diodes are connected in antiparallel to the second semiconductor switching element in antiparallel to each other to form a bidirectional conduction path;
a control circuit for controlling ON/OFF operations of the first semiconductor switching element, the conducting portion switching element, and the second semiconductor switching element;
with
The control circuit cuts off the main conduction portion by controlling the conduction portion switching element and the first semiconductor switching element in that order, and cuts off the main conduction portion by controlling the second semiconductor switching element. A current breaker that applies a reverse bias to the first semiconductor switching element by turning off the gate of the conduction part switching element in the ON state of . A current circuit breaker comprising a main conduction part that is a current conduction part and an auxiliary conduction part connected in parallel to the main conduction part,
The main conduction portion includes a first semiconductor switching element having no self arc-extinguishing function, and a conduction portion switching element connected in series with the first semiconductor switching element for switching the conduction portion by an on/off operation. , formed by
the auxiliary conduction part is formed by a second semiconductor switching element,
a control circuit for controlling ON/OFF operations of the first semiconductor switching element, the conducting portion switching element, and the second semiconductor switching element;
with
The control circuit interrupts the main conduction portion by controlling the conduction portion switching element and the first semiconductor switching element in this order, and when interrupting the main conduction portion, the conduction portion switching element, the A current interrupter , wherein a first semiconductor switching element is controlled with a preset time difference ΔT, wherein the time difference ΔT is a time for obtaining a reverse bias sufficient to pull out the charge of the first semiconductor switching element . A current circuit breaker comprising a main conduction part that is a current conduction part and an auxiliary conduction part connected in parallel to the main conduction part,
The main conduction section has a pair of series circuits each including a configuration in which a first semiconductor switching element having no self-extinguishing function and a conduction section switching element are connected in series, and the pair of series circuits are connected to each other. connected in anti-parallel,
the auxiliary conducting portion is formed by connecting a pair of parallel circuits in which diodes are connected in antiparallel to the second semiconductor switching element in antiparallel to each other to form a bidirectional conduction path;
a control circuit for controlling ON/OFF operations of the first semiconductor switching element, the conducting portion switching element, and the second semiconductor switching element;
with
The control circuit interrupts the main conduction portion by controlling the conduction portion switching element and the first semiconductor switching element in this order, and when interrupting the main conduction portion, controls the conduction portion switching element and the first semiconductor switching element. A current interrupter , wherein a first semiconductor switching element is controlled with a preset time difference ΔT, wherein the time difference ΔT is a time for obtaining a reverse bias sufficient to pull out the charge of the first semiconductor switching element . The control circuit turns on the second semiconductor switching element when the first semiconductor switching element, the conducting portion switching element, and the second semiconductor switching element are in an off state, and then turns on the first semiconductor switching element. The current breaker according to any one of claims 1 to 4 , which turns on the switching element. A control signal is externally applied to the control circuit, and the control signal provides a predetermined time difference to the control signal so that the first semiconductor switching element, the conducting portion switching element, 6. The current breaker according to claim 5 , wherein timings of ON and OFF operations of said second semiconductor switching element and said second semiconductor switching element are respectively shifted. 7. The first semiconductor switching element, the conduction switching element and the second semiconductor switching element according to any one of claims 1 to 6 , formed by a thyristor, a MOSFET and an IGBT, respectively. current circuit breaker.

Images