WO2017150079A1

WO2017150079A1 - Direct current circuit breaker

Info

Publication number: WO2017150079A1
Application number: PCT/JP2017/004200
Authority: WO
Inventors: 康一安岡; 希竹内; 祥紀坪井; 早川　達也
Original assignee: 国立大学法人東京工業大学
Priority date: 2016-03-02
Filing date: 2017-02-06
Publication date: 2017-09-08
Also published as: JPWO2017150079A1

Abstract

This direct current circuit breaker 2 comprises a main circuit breaker 4 and a semiconductor switch 8. The main circuit breaker 4 is provided on a main path 6, and the semiconductor switch 8 is provided on an alternative path 10 parallel to the main path 6. This direct current circuit breaker 2 is configured in such a manner that, at opening time of the contact poles from the main circuit breaker 4, the semiconductor switch 8 is turned ON before the inter-contact voltage Vc arising between the two ends of the main circuit breaker 4 reaches a boiling voltage Vb.

Description

DC circuit breaker

The present invention relates to a DC circuit breaker.

DC transmission is not so popular in theory, although it is more efficient than AC transmission. At present, except for railways, direct current power transmission is used only for photovoltaic power generation facilities and other relatively small systems.

遮断 Blocking is one of the factors that hinder the spread of DC power transmission. When an electrical contact on a path through which a large current flows is opened (turned off), an arc discharge occurs between the contacts. In the case of alternating current, since there is a zero point, the arc discharge is extinguished within a few cycles. On the other hand, in the case of direct current, since a high voltage is continuously applied between the contacts, arc discharge continues, it is difficult to interrupt the current, and a direct current circuit breaker is required.

As a DC circuit breaker, a structure in which a main circuit breaker (electrical contact) and a semiconductor element are connected in parallel has been proposed (see Patent Document 1, Non-Patent Documents 1 and 2). Such a DC circuit breaker is also referred to as a hybrid DC circuit breaker.

JP 2013-196895 A

1 (a) to 1 (e) are diagrams for explaining the operation of a conventional hybrid DC circuit breaker. FIG. 1A shows a state where the main circuit breaker 900 is on and a current flows between the fixed contact 902 and the movable contact 904. When any accident or failure occurs, the movable contact 904 is separated from the fixed contact 902 based on the opening command, and the resistance between the contacts increases. Even if the movable contact 904 and the fixed contact 902 are in a non-contact state, the current i continues to flow in the gap between them, and the voltage (voltage drop) Vc between the contacts increases.

As shown in FIG. 1B, when the contact voltage Vc, which increases with the contact opening of the main circuit breaker 900, becomes the melting voltage Vm, a melting bridge 910 is generated. Further, when the inter-contact voltage Vc exceeds the boiling voltage Vb, as shown in FIG. When transitioning to arc discharge, the potential difference between the contacts increases to about 10-20V. The hybrid DC circuit breaker uses a high voltage of about 10 to 20 V (referred to as arc voltage Va) generated during arc discharge to conduct a semiconductor switch in parallel with the main circuit breaker 900 and includes a semiconductor switch. Dissipates energy while diverting current to the secondary path. Eventually, as shown in FIG. 1D, the arc is extinguished and the metal particles 914 are diffused. Thereafter, as shown in FIG. 1E, the interruption is completed, and the insulation is restored.

Here, as shown in FIG. 1 (d), the metal particles 914 forming the

contacts

902 and 904 are scattered by arc discharge, so the contact is inevitably consumed. For this reason, it has been difficult to use the DC circuit breaker for a long time with no maintenance. In addition, a shield 922 may be necessary to prevent the scattered metal particles 914 from adhering to the vacuum vessel 920 or the like. The shield 922 prevents the main circuit breaker 900 from being downsized.

The present invention has been made in such a situation, and one of exemplary purposes of an aspect thereof is to provide a DC circuit breaker capable of reducing contact wear.

A certain aspect of the present invention is a DC circuit breaker. The DC circuit breaker includes a main circuit breaker provided on the main path and a semiconductor switch provided on a sub-path parallel to the main path. The DC circuit breaker is configured to commutate to the semiconductor switch before arc discharge starts when the main circuit breaker contacts are opened.

A certain aspect of the present invention also relates to a DC circuit breaker. The DC circuit breaker includes a main circuit breaker provided on the main path and a semiconductor switch provided on a sub path parallel to the main path. The DC circuit breaker is configured such that when the contact of the main circuit breaker is opened, the semiconductor switch is turned on before the contact voltage Vc generated between both ends of the main circuit breaker reaches the boiling voltage Vb.

According to these aspects, until commutation and arc extinction are completed, commutation is possible without causing arc discharge between the contacts of the main circuit breaker (referred to as arcless commutation), and contact consumption can be reduced.

The DC circuit breaker may be configured such that the semiconductor switch is turned on before the contact voltage Vc generated across the main circuit breaker reaches the melting voltage Vm.
As a result, commutation from the previous stage of bridge formation to the semiconductor switch can be started, and the contact voltage Vc can be suppressed to a lower voltage level.

The semiconductor switch may include a plurality of SiC MOSFETs connected in parallel.
SiC MOSFET has small ON resistance _{R ON} as compared to the IGBT, also by paralleling the amount of current flowing through each transistor is reduced. For this reason, the drain-source voltage required to pass a certain current i can be reduced.

When the DC inductance of the main path including the main circuit breaker is L, the DC inductance of the sub path is L _S , the on-resistance of the semiconductor switch is R _ON , and the current flowing through the semiconductor switch is i, the configuration is such that Expression (1) holds May be.
_{(L + L S) · di} / dt + R ON · i <Vb ... (1)
By designing in consideration of the inductance, reliable arcless commutation is possible.

The semiconductor switch may be in close contact with the casing of the main circuit breaker, or may be incorporated in the same module. Thus, the parasitic impedance (inductance L, L _S or DC resistance) can reduce the voltage drop due, therefore a smaller contact voltage, it is possible to turn on the semiconductor switch.

The DC circuit breaker of a certain aspect may further include a snubber capacitor provided in parallel with the main path including the main circuit breaker and the sub path. Since the snubber capacitor can suppress the jump of the inter-contact voltage Vc, it is difficult to transfer from the melting bridge to the arc discharge.

The main circuit breaker may include a plurality of electrical contacts connected in series. As a result, the terminal voltage across the main circuit breaker, in other words, the voltage across the semiconductor switch, is the sum of the voltages across the plurality of electrical contacts. Therefore, the semiconductor switch can be made conductive with the voltage between both ends of each electrical contact being low.

A pair of semiconductor switches connected in reverse series may be provided in the sub route. Thereby, it can be used to cut off a bidirectional DC system or an AC system.

It should be noted that a combination of the above-described components arbitrarily or a conversion of the expression of the present invention between a method, an apparatus, etc. is also effective as an aspect of the present invention.

According to an aspect of the present invention, contact wear can be reduced.

FIGS. 1A to 1E are diagrams for explaining the operation of a conventional hybrid DC circuit breaker. It is an equivalent circuit diagram of the DC circuit breaker according to the embodiment. It is an equivalent circuit diagram of the DC circuit breaker considering the parasitic element. FIG. 4A is a diagram for explaining arc commutation by a conventional hybrid DC circuit breaker, and FIG. 4B is a waveform diagram for explaining arcless commutation by the DC circuit breaker according to the embodiment. . FIGS. 5A to 5E are circuit diagrams of DC circuit breakers according to first to fifth embodiments. It is sectional drawing of the DC circuit breaker which concerns on 4th Example. FIG. 7A is an operation waveform diagram of the DC circuit breaker of FIG. 6 having two contacts, and FIG. 7B is an operation waveform diagram of the DC circuit breaker having one contact. It is a table which shows the softening / melting / boiling voltage of various contact materials. 9A and 9B are a plan view and a cross-sectional view of an electrode structure using C (carbon) as an electrode material. It is an operation | movement waveform diagram of the arcless commutation by a DC circuit breaker provided with the electrode structure of FIG.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

FIG. 2 is an equivalent circuit diagram of the DC circuit breaker according to the embodiment. The DC circuit breaker 2 includes a main circuit breaker 4, a semiconductor switch 8, and a surge absorber 12. The main circuit breaker 4 is an electrical contact disposed on the main path 6 of the DC system to be interrupted. The semiconductor switch 8 is provided on a sub route 10 parallel to the main route 6 including the main circuit breaker 4. The semiconductor switch 8, MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT may be used (Insulated Gate Bipolar Transistor), a small on-voltage _{V ON} between the drain source as described below, in other words on-resistance _{R ON} having a small, in other words, for the same drain-source voltage V _DS, it is preferable to select a device that can safely more current, from this viewpoint, it is preferable to use a MOSFET of SiC (silicon carbide).

A voltage smaller than the threshold voltage is input between the gate and source of the semiconductor switch 8 while the contact of the main circuit breaker 4 is closed (on), and the threshold is linked with the opening (off) command. A voltage greater than the voltage is input. Alternatively, a voltage larger than the threshold voltage may be constantly applied between the gate and source of the semiconductor switch 8.

The surge absorber 12 is also referred to as an arrester and is connected in parallel to the main route 6 and the sub route 10. The surge absorber 12 is provided to dissipate the current that flows after the main circuit breaker 4 is opened (turned off), and the arrangement location is not particularly limited.

Thus, the basic configuration of the DC circuit breaker 2 is similar to the conventional hybrid DC circuit breaker on the equivalent circuit, but is greatly different in that it does not appear in the equivalent circuit. Hereinafter, differences will be described.

As described above, the conventional DC circuit breaker has a high contact voltage Vc of about 10 to 20 V (hereinafter referred to as arc voltage Va) between both ends of the main circuit breaker due to arc discharge when the contact of the main circuit breaker is opened. ) Occurs. The high arc voltage Va is applied between the drain and source of the semiconductor switch to make the semiconductor switch conductive. Hereinafter, this is referred to as arc commutation.

On the other hand, the DC circuit breaker 2 according to the embodiment is configured such that when the contact of the main circuit breaker 4 is opened, the semiconductor switch 8 is turned on before the arc discharge starts and commutation starts. ing. Hereinafter, this is referred to as arcless commutation.

1C is generated when the voltage Vc between the contacts of the main circuit breaker 4 exceeds a certain threshold voltage (boiling voltage) Vb. Therefore, from another viewpoint, the DC circuit breaker 2 according to the embodiment is configured so that the contact voltage Vc (drain-source voltage) reaches the boiling voltage Vb when the contact of the main circuit breaker 4 is opened. 8 is configured to be turned on.

Here semiconductor switch, in a state where the high level voltage is applied to the gate, the drain-source voltage V _DS is turned exceeds the phrase on voltage V _ON. Note that the ON voltage V _ON in this specification is a convenient numerical value that represents a drain-source voltage necessary for flowing a certain current i, and does not exist as a device parameter. The ON voltage V _ON depends on the flowing current i, and can be expressed as V _ON = R _ON × i. Note that the on-resistance _RON itself is also a function of the current i.

Neglecting the influence of the parasitic elements, the drain-source voltage V _DS of the semiconductor switch 8 is equal to the inter-terminal voltage Vc. Therefore, the condition for arcless commutation is expressed by equation (2).
V _ON <Vc (≈V _DS ) <Vb (2)

As shown in FIG. 1B, a melting bridge 910 is formed between the contacts before the arc discharge occurs. The melting bridge 910 is generated when the inter-contact voltage Vc reaches the melting voltage Vm. Therefore, more preferably, the DC circuit breaker 2 according to the embodiment is switched before the bridge formation starts, in other words, before the inter-terminal voltage Vc reaches the melting voltage Vm, when the contact of the main circuit breaker 4 is opened. The flow may be started. The condition in this case is expressed by equation (3).
V _ON <Vc (= V _DS ) <Vm <Vb (3)

The melting voltage Vm varies depending on the material of the contact. Typically, if the melting voltage Vm is 0.5 to 1 V, the _ON voltage V _ON of the semiconductor switch 8 may be designed in the order of 0.5 to 1 V. As an example, the boiling voltage Vb of Au (silver) is 0.77 V, the melting voltage Vm is 0.37 V, and the softening voltage is 0.11 V. The softening voltage is a voltage generated when the contact pressing force is weakened when the contact is opened and the contact resistance between the contacts is increased, and corresponds to 50 to 85 μs in FIG.

In other words, in order to satisfy formula (2) or formula (3),
(I) To reduce the _ON voltage V _ON (ON resistance R _ON ) of the semiconductor switch 8,
(Ii) To increase the inter-terminal voltage Vc,
(Iii) To increase the melting voltage Vm and the boiling voltage Vb,
The DC breaker 2 may be designed. A specific approach for realizing arcless commutation will be described later.

FIG. 3 is an equivalent circuit diagram of the DC circuit breaker 2 in consideration of parasitic elements. The main path 6 includes an inductor L in series with the main circuit breaker 4, and the sub path 10 includes an inductor L _{S in} series with the semiconductor switch 8. When these parasitic elements are taken into consideration, the arcless commutation condition is given by equation (1).
_{(L + L S) · di} / dt + R ON · i <Vb ... (1)
Therefore, the parasitic inductance L, if the parasitic impedances such as L _S can not be ignored, so as to satisfy the equation (1) may be designed to DC circuit breaker 2. If there is a parasitic DC resistance, it should be taken into account.

When the parasitic impedance cannot be ignored, it is more preferable to design so as to satisfy the formula (4) so that commutation starts at the melting voltage Vm.
_{(L + L S) · di} / dt + R ON · i <Vm ... (4)

The above is the basic configuration of the DC circuit breaker 2. Next, the operation will be described. 4A is a diagram for explaining arc commutation by a conventional hybrid DC circuit breaker, and FIG. 4B is a waveform diagram for explaining arcless commutation by the DC circuit breaker 2 according to the embodiment. is there.

First, conventional arc commutation will be described with reference to FIG. A conventional DC circuit breaker is constituted by an IGBT. The contact closed state is before time 0 μs, and a contact current ic of 140 A flows. The contact opens at time 0 μs. The inter-contact voltage Vc increases with time. At t = 50 to 90 μs, the inter-terminal voltage Vc reaches the melting voltage Vm (0.37 V) to form a bridge, and the inter-terminal voltage Vc boils at 90 to 105 μs. When the voltage Vb (0.77 V) is exceeded, transition to arc discharge occurs. With the start of arc discharge, the voltage Vc between terminals, that is, the collector-emitter voltage of the semiconductor switch exceeds the _ON voltage V _ON (0.7 V), the semiconductor switch becomes conductive, the current i _IGBT flowing through the _IGBT increases, and the contact current ic Decreases and commutation takes place.

Next, arcless commutation of the DC breaker 2 according to the embodiment will be described with reference to FIG. The semiconductor switch 8 is composed of a MOSFET, and the on-voltage V _ON is as small as 0.1V to 0.2V.

A contact current of 140 A flows before time t = 0 μs, and the contact opens at time 0 μs. When the contact voltage Vc slightly increases to about 0.1 V to 0.2 V, the current i _DS flows through the semiconductor switch 8 and commutation starts. When the current i _DS flows through the semiconductor switch 8, the contact current i _C decreases, so that an increase in the contact voltage Vc is suppressed. As a result, the contact voltage Vc continues to maintain the range of 0.5 to 1 V during the commutation period, does not reach the boiling voltage Vb, and no arc discharge occurs.

The above is the operation of the DC circuit breaker 2 according to the embodiment.
According to the DC circuit breaker 2, since it is possible to commutate to the semiconductor switch without generating arc discharge, it is possible to reduce contact consumption and extend the life.

In addition, since there are no charged particles or metal vapor generated by the arc between the contacts, there is an advantage that the insulation recovery between the contacts is quick. The DC circuit breaker fails to shut off if the semiconductor switch is turned off before the insulation is recovered. However, since the insulation recovery is fast, the restriction on the turn-off timing of the semiconductor switch is relaxed.

Also, the DC circuit breaker 2 has the further advantage that the distance between the contacts of the main circuit breaker 4 can be shortened because arc discharge does not occur. Thereby, the direct-current circuit breaker 2 can be reduced in size. Further, since the moving distance of the movable contact is short, piezo driving is possible, and in this case, the device can be further downsized.

Moreover, since the metal particles released into the gas or vacuum accompanying the discharge can be significantly reduced, contamination can be prevented. By reducing the scattered metal particles, the shield 922 shown in FIG. 1 (e) can be eliminated, and in this case, the size and cost of the DC breaker 2 can be reduced.

Also, since arc discharge does not occur, interruption in the atmosphere can be taken as an option. In this case, since a vacuum is not required, the cost of the apparatus can be greatly reduced.

Subsequently, an approach for realizing arcless commutation in the DC circuit breaker 2 will be described with reference to some examples.

(First approach)
FIG. 5A is a circuit diagram of the DC circuit breaker 2a according to the first embodiment. The semiconductor switch 8a may include a plurality of transistors (for example, MOSFETs) M1 and M2 connected in parallel. The number of transistors is not particularly limited, and may be selected so as to satisfy the conditions of arcless commutation. However, as a result of studies by the present inventors, arcless commutation is achieved by connecting four MOSFETs in parallel as shown in FIG. An arcless commutation was also confirmed in the parallel connection of two MOSFETs. In FIG. 5A, the body diode (freewheeling diode) is omitted.

By parallel connecting a plurality of transistors, it is possible to reduce the on-resistance R _ON of the semiconductor switch 8a. As a result, the current i can be commutated to the semiconductor switch 8a at a smaller inter-terminal voltage Vc.

(Second approach)
Referring to Equation (3) or (4), by reducing the parasitic inductances L and L _S , the left side can be reduced, and therefore arcless commutation is facilitated. FIG.5 (b) is sectional drawing of the direct-current circuit breaker 2b which concerns on 2nd Example. The main circuit breaker 4b is a general electric contact, and includes a fixed contact 902, a movable contact 904, a bellows 906, and the like. In the DC circuit breaker 2b, a commercially available power module including the semiconductor switch 8b is in close contact with the casing (housing) of the main circuit breaker 4. As a result, the wiring length can be shortened, and the inductance and parasitic resistance can be reduced.

When a plurality of transistors are connected in parallel as shown in FIG. 5A, a plurality of power modules may be attached to the casing of the main circuit breaker 4b.

As described above, since the main circuit breaker 4 can be reduced in size as compared with the prior art, the main circuit breaker 4 and the semiconductor switch 8 may be incorporated in the same package or the same module. As a result, the inductance can be further reduced.

(Third approach)
FIG. 5C is a circuit diagram of the DC circuit breaker 2c according to the third embodiment. The DC circuit breaker 2 c further includes a snubber capacitor 14 provided in parallel with the main path 6 and the sub path 10.

Since the jump of the contact voltage Vc can be suppressed by the snubber capacitor 14, it is difficult to make transition from the melting bridge to the arc discharge.

(Fourth approach)
FIG. 5D is a circuit diagram of the DC circuit breaker 2d according to the fourth embodiment. In the DC circuit breaker 2d, the main circuit breaker 4d includes a plurality of electrical contacts 4_1 to 4_2 connected in series. The contact voltage Vc of the entire main circuit breaker 4d is the sum of the contact voltages Vc1 to Vc2 of the individual electrical contacts. Therefore, the semiconductor switch 8 can be turned on while the voltage Vc1 and Vc2 between both ends of each of the electrical contacts 4_1 to 4_2 is low, and arc discharge hardly occurs at the electrical contacts 4_1 and 4_2. The number of electrical contacts is not particularly limited.

FIG. 6 is a cross-sectional view of the DC circuit breaker 2d according to the fourth embodiment. An equivalent circuit diagram of the DC circuit breaker 2d is shown in FIG. The DC circuit breaker 2d includes two fixed electrodes 20_1 and 20_2 and two movable electrodes 22_1 and 22_2. A pair of the fixed electrode 20_1 and the movable electrode 22_1 corresponds to the electrical contact 4_1 in FIG. 5D, and is disposed to face each other with a gap 24 therebetween. Similarly, the pair of the fixed electrode 20_2 and the movable electrode 22_2 corresponds to the electrical contact 4_2 in FIG. 5D, and is disposed to face each other with a gap 24 therebetween. The two movable electrodes 22_1 and 22_2 may be integrally formed.

The two movable electrodes 22_1 and 22_2 are attached to the piezo actuator 26. By driving the piezo actuator 26, the distance of the gap 24 is changed, and the fixed electrode 20 and the movable electrode 22 facing each other can be attached and detached.

7A is an operation waveform diagram of the DC circuit breaker 2d of FIG. 6 having two contacts, and FIG. 7B is an operation waveform diagram of the DC circuit breaker having one contact. FIG. 8 is a table showing the softening / melting / boiling voltage of various contact materials.

The boiling voltage of copper is 0.8V. As shown in FIG. 7B, in the case of a single contact, arc discharge occurs when the contact voltage is less than 1V, and the contact voltage reaches 20V (in FIG. 7B). On the other hand, when the number of contacts is increased to 2, as shown in FIG. 7A, it can be seen that even if the contact voltage exceeds 1.5V, it does not boil and arc discharge does not occur. Thus, arc discharge can be suppressed by increasing the number of contacts.

(Fifth approach)
The fifth approach is to increase the boiling voltage Vb. For this purpose, it is effective to select a high melting point material for the contact of the main circuit breaker 4, and Ag (silver), Ni (nickel), W (Tungsten) or alloys thereof are useful. For example, regarding the melting point, Ag is 961 ° C., Ni is 1455 ° C., and W is 3382 ° C. Their melting voltage Vm is 0.38 to 0.64 V for Ag, 0.55 to 1.1 V for Ni, and 0.6 to 1.0 V for Ag—W alloy (PP Koren, IEEE Parts, Hybrids & Packaging, vol. PHP-11, no.1 pp.4-10 (1975)).

Instead of using a material having a high boiling voltage Vb as the electrode material of the contact, the following approach can be taken.
9A and 9B are a plan view and a cross-sectional view of an electrode structure using C (carbon) as an electrode material. On the surface of the Cu electrode plate 30, a carbon film 32 (thickness: 200 μm) is fixed in close contact using a screw 34. As shown in FIG. 8, since carbon is not a metal, the softening / melting / boiling voltage cannot be defined, but has a sublimation temperature of 3642 ° C.

FIG. 10 is an operation waveform diagram of arcless commutation by a DC circuit breaker having the electrode structure of FIG. As shown in FIG. 10, the commutation is completed after the contact voltage rises to about 7.5V. When the Si-MOSFET was not turned on, arc discharge occurred at a contact voltage of about 9.0 V, and the voltage rose to 30 V. By using carbon as an electrode, a contact voltage higher than that of tungsten can be obtained.

At contact opening time 0 shown in FIG. 10, a contact voltage of about 2V is generated, which is larger than the other waveform diagrams. This is because the normal contact resistance is 1 mΩ or less, whereas the electrode structure of FIG. 9 has a contact resistance of 13 mΩ (2 V / 150 A). The poor adhesion between the plate 30 and the carbon film 32 is one of the factors.

In other words, if the adhesion between the electrode plate 30 and the carbon film 32 is increased, the contact resistance can be sufficiently reduced. Therefore, a carbon film or a graphene film may be formed on the surface of the electrode plate 30 by a plasma CVD method, or a carbon film or a graphene film may be formed by a hot press molding method. As a result, the adhesion between the electrode plate 30 and the carbon film 32 can be increased, the contact resistance can be reduced, and the contact voltage before contact opening can be reduced.

(Other examples)
After the MOSFET which is the semiconductor switch 8 is turned off and the energy is absorbed by the surge absorber (arrester, varistor), the MOSFET must withstand the circuit voltage. The rated voltage of the MOSFET for large current is 1200 V, 3300 V, etc., and the circuit voltage is required to be lower than the rated voltage of the MOSFET. When it is desired to use for an application with a large circuit voltage, a plurality of MOSFETs may be connected in series.

FIG. 5E is a circuit diagram of the DC circuit breaker 2e according to the fifth embodiment. In the DC circuit breaker 2e, the sub path 10 is provided with a pair of semiconductor switches 8_1 and 8_2 connected in reverse series. This DC circuit breaker 2e can also be used for bidirectional DC system or AC system interruption.

It should be noted that the various circuit configurations shown in FIGS. 5A to 5E and the above-mentioned several approaches can be arbitrarily combined.

Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

2 ... DC circuit breaker, 4 ... main circuit breaker, 6 ... main path, 8 ... semiconductor switch, 10 ... sub-path, 12 ... surge absorber.

The present invention can be used for power transmission.

Claims

A DC circuit breaker,
A main circuit breaker provided on the main path;
A semiconductor switch provided on a sub-path parallel to the main path;
With
The DC circuit breaker is configured to commutate to the semiconductor switch before arc discharge starts when the contact of the main circuit breaker is opened.
A DC circuit breaker,
A main circuit breaker provided on the main path;
A semiconductor switch provided on a sub-path parallel to the main path;
With
The DC circuit breaker is configured such that when the contact of the main circuit breaker is opened, the semiconductor switch is turned on before the contact voltage Vc generated between both ends of the main circuit breaker reaches the boiling voltage Vb. DC breaker characterized by that.
The said DC circuit breaker is comprised so that the said semiconductor switch may be turned on before the voltage Vc between contacts generated between the both ends of the said main circuit breaker reaches the fusion voltage Vm. The DC circuit breaker described.
4. The DC circuit breaker according to claim 1, wherein the semiconductor switch includes a plurality of SiC MOSFETs connected in parallel.
When the DC inductance of the main path including the main circuit breaker is L, the DC inductance of the sub path is L S , the ON resistance of the semiconductor switch is R ON , and the current flowing through the semiconductor switch is I, the formula (1) The DC circuit breaker according to any one of claims 1 to 4, wherein:
(L + L S ) · dI / dt + R ON · I <Vb (1)
The DC circuit breaker according to any one of claims 1 to 5, wherein the semiconductor switch is in close contact with the casing of the main circuit breaker or is built in the same module.
The DC circuit breaker according to any one of claims 1 to 6, further comprising a snubber capacitor provided in parallel to the main circuit breaker and the sub route.
The DC circuit breaker according to any one of claims 1 to 7, wherein the main circuit breaker includes a plurality of electrical contacts connected in series.
The DC circuit breaker according to any one of claims 1 to 8, wherein the sub-path is provided with a pair of semiconductor switches connected in reverse series.
10. The DC circuit breaker according to claim 1, wherein the electrical contact of the main circuit breaker is Ag (silver), Ni (nickel), W (tungsten) or an alloy thereof.
10. The DC circuit breaker according to claim 1, wherein the electrical contact of the main circuit breaker includes a metal and a carbon film provided on the metal.