JPH0628952A - Direct current circuit breaker - Google Patents

Abstract

PURPOSE:To break a circuit by changing a flow of a load current even when an electric current is flowed in both directions to a load in a direct current circuit breaker used to protect direct current electric power supply such as electric power supply for nuclear fusion or electric power supply for a superconducting electromagnet. CONSTITUTION:A direct current circuit breaker is composed of a breaking switch 4 situated between direct current electric power supply 1 and a load 2 so as to be connected in parallel to the load 2 and a flow changing circuit 6 connected in parallel to the breaking switch, and the flow changing circuit is composed of a capacitor 7 and a reactor 8 connected at least in series to each other. In the direct current circuit breaker constituted so as to negate an electric current flowing to the breaking switch 4 by a resonance current caused by these capacitor and reactor, switch means 13-16 are provided to switch a connecting direction of the breaking switch 4 and the flow changing circuit 6 to the positive or the negative to the load 2 according to a direction of the electric current flowing to the load 2 from the direct current electric power supply 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC circuit breaker for protecting a DC power source such as a nuclear power source or a superconducting electromagnet power source.

[0002]

2. Description of the Related Art FIG. 13 shows a circuit configuration of a conventional DC circuit breaker disclosed in Japanese Patent Application No. 60-171796. In FIG. 13, 1 is a variable voltage type DC power source (hereinafter abbreviated as “DC power source”), 2 is a load such as an electromagnet coil (hereinafter referred to as “load coil”) supplied with current from the DC power source 1,
Reference numeral 3 is a first switch such as an ignitron switch connected to the DC power supply 1. 4 is a cutoff switch connected to the load coil 2 side of the first switch, 5 is a cutoff switch 4
A rectifying device such as a diode connected between the load 1 and the load 1, and a commutation circuit 6 connected in parallel to the cutoff switch 4 and the rectifying device 5.

Reference numeral 7 is a capacitor which constitutes the commutation circuit 6, and 8
Is an inductor connected in series to the capacitor 7, and 9 is a second switch for connecting a commutation circuit connected in series to the inductor 8. 10 is a breaking resistance that absorbs energy of the load coil 2 at the time of DC cutoff, 11 is a crowbar diode connected between the connection point between the switch 3 and the breaking switch 4 and one end of the DC power supply 1, and 12 is parallel to the breaker 4. Is a voltage detection circuit connected to.

The operation of the circuit will be described with reference to the waveform diagram of FIG. First, in order to energize the load coil 2, the first
Switch 3 is closed. As a result, a current is supplied to the load coil 2 from the DC power supply 1, and the load coil 2 is excited. When the voltage of the DC power supply 1 is lowered after the current flowing through the load coil 2 reaches a certain constant value I ₁ , the action of the crowbar diode 11 causes a constant current within the range of the time constant set for the circuit to be energized. And the DC power supply 1 is disconnected from the load coil 2.

Next, when a failure or the like occurs at time t ₃ in FIG. 14, the cutoff switch 4 is opened, and at the same time, the second switch 9 is closed. In general, jitter often occurs when the cutoff switch 4 is opened. Therefore, as an actual operation, the cutoff switch 4
The voltage detection circuit 12 detects the voltage increase at both ends when the switch is opened, and the second switch 9 is closed by this detection output.

By closing the second switch 9 in this manner, a reverse current I ₂ flows from the capacitor 7 transiently, and the current flowing through the cutoff switch 4 is rapidly attenuated at this time. It becomes zero at t ₄ . At this time t
_In the time zone from ₃ to time t ₄ , arc plasma is generated between the electrodes of the cutoff switch 4.

After the time point t ₄ , until the predetermined time point t ₅ , the current flowing through the breaking switch 4 is maintained at zero by the action of the rectifying element 5. Then, in the time period from the time point t ₄ to the time point t ₅ , the arc plasma generated between the electrodes of the cutoff switch 4 is sufficiently attenuated and finally disappears.

After the time point t _5, the current from the capacitor 7 tries to flow into the cutoff switch 4, but at this time, the cutoff switch 4 cannot be flown because it is already completely opened, and the desired cutoff operation is performed. Upon completion, the current flowing through the load coil 2 flows through the breaking resistor 10 and is attenuated here. When the rectifying element 5 in FIG. 13 is removed, when the cutoff fails, the current shown by the dashed line in FIG. 14 flows.

[0009]

Since the conventional DC circuit breaker is constructed as described above, the current can flow only in one direction. Moreover, since the commutation circuit 6 is fully charged regardless of the magnitude of the interrupted current, there is a problem that it cannot cope with a load that changes the current value. Further, there is no protection against the failure of breaking by the breaking switch 4, and there is a problem that the load may be damaged when the breaking fails.

The present invention has been made to solve the above problems, and provides a DC circuit breaker capable of commutating and breaking the load current even when the current is passed in both positive and negative directions with respect to the load. The purpose is to Another object of the present invention is to obtain a DC circuit breaker that can be interrupted even when the value of the current flowing through the load is changed to a triangular wave or the like. Another object of the present invention is to obtain a DC circuit breaker that can surely interrupt the current by diverting the current to the protective fuse side even when the interruption by the interruption switch fails.

[0011]

SUMMARY OF THE INVENTION A first DC circuit breaker according to the present invention comprises a switch means for switching the connection direction of a breaking switch and a commutation circuit to the load depending on the direction of a current flowing from a DC power supply to the load. It is configured by being provided.

The second DC circuit breaker according to the present invention is configured by providing a changeover switch for switching the connection direction of the commutation circuit to the load according to the direction of the current flowing from the DC power supply to the load. .

A third DC circuit breaker according to the present invention is constructed by providing a charge / discharge control means for controlling the charging voltage of the capacitor of the commutation circuit in accordance with the load current.

A fourth DC circuit breaker according to the present invention is constructed by providing a protective fuse and a protective fuse closing switch for connecting and closing the protective fuse in parallel with the breaking switch.

[0015]

According to the first DC circuit breaker of the present invention, the connection direction of the breaking switch and the commutation circuit is switched between positive and negative depending on the direction of the current flowing from the DC power source to the load, and the current is independent of the direction of the main circuit current. Shut off.

The second DC circuit breaker according to the present invention switches the direction of connection of the commutation circuit to the load according to the direction of the current flowing from the DC power supply to the load, and the current is irrespective of the direction of the main circuit current. Shut off.

The third DC circuit breaker according to the present invention controls by charging or discharging the charging voltage of the capacitor of the commutation circuit according to the load current so that the load current is changed even if the load current changes. The reverse current of the matched current value is passed through the cutoff switch to cut off the current.

In the fourth DC circuit breaker according to the present invention, the protective fuse is connected in parallel with the breaking switch so that when the current is flowing through the breaking switch, the protective fuse is diverted to the protective fuse so that the protective fuse is The current is cut off by fusing.

[0019]

【Example】

[First Embodiment] FIG. 1 shows a first embodiment of a DC circuit breaker according to the present invention. In FIG. 1, 1 is a bipolar DC power supply, 2 is a load coil, 3 is a first switch, 4 is a breaking switch, 5 is a rectifying element connected in series with the breaking switch 4, 6 is a breaking switch 4 and a rectifier A commutation circuit 10 connected in parallel with the element 5 is a breaking resistance.

Reference numeral 13 denotes A in the main circuit and the rectifying element 5 side of the DC cutoff portion including the breaking switch 4, the rectifying element 5, and the commutation circuit 6.
, 14 is a changeover switch connected between the breaker switch 4 side of the DC cutoff unit and the main circuit B side, and 15 is a cutoff switch 4 side of the DC cutoff unit and the main circuit B. A changeover switch connected to the A side, 16 a changeover switch connected between the rectifying element 5 side of the DC cutoff section and the B side of the main circuit, and 17 a current for detecting the current from the DC power supply 1. The detector, 18 is a changeover switch selection unit that determines the energization direction based on the detection signal of the current detector 17 and selects the switch to be turned on.

The operation of the circuit shown in FIG. 1 will be described. First, when a current is flowing from the bipolar DC power source 1 to the load coil 2 in the direction A, when a quench or the like occurs in the load coil 2, the changeover switch selection unit 18 causes the changeover switch selection unit 18 to output a detection signal from the current detection unit 17. The switch to be turned on is selected, and the changeover switch 15 and the changeover switch 16 are turned on.

When the change-over switch 15 and the change-over switch 16 are turned on, the DC power source 1 shifts to the operation of inverting the output current, and the current that continues to flow in the load coil 2 is cut off from the cutoff switch 4, the rectifying element 5, and the commutation circuit 6. Return to the load coil 2 through the DC cutoff unit. After that, the DC power supply 1 is disconnected from the circuit by the switch 3, and the DC cutoff unit including the cutoff switch 4, the rectifying element 5, and the commutation circuit 6 performs the cutoff operation.

Next, when a current or the like is applied to the load coil 2 in the B direction and a quench or the like occurs in the load coil 2, the changeover switches 13 and 14 are turned on. Thereafter, the same operation as in the case where the current is flowing in the A direction is performed, and the interruption operation is performed by the DC interruption section including the interruption switch 4, the rectifying element 5, and the commutation circuit 6.

As described above, by selecting to turn on the changeover switches 15 and 16 or the changeover switches 13 and 14 in the direction of the current flowing through the load coil 2, the cutoff switch 4, the rectifying element 5, and the commutation circuit 6 are selected. Since the direction of the current flowing through the DC cut-off section is always one direction, the current can be cut off by one DC cut-off section against the load current in both directions.

In the first embodiment described above, the case where the breaking switch 4 and the rectifying element 5 are connected in series has been described. However, as shown in FIG. However, the same effect as described above can be obtained. Further, as shown in FIG. 5, the changeover signal of the changeover switch may be inputted from the outside.

[Second Embodiment] FIG. 2 shows a second embodiment of the DC circuit breaker according to the present invention. In the first embodiment, by selectively turning on the changeover switches 15 and 16 or the changeover switches 13 and 14, regardless of the direction of the load current,
Although a current in a fixed direction is made to flow through a direct current cutoff portion composed of the cutoff switch 4, the rectifying element 5, and the commutation circuit 6 to cut off the current, as shown in FIG. The switches 19 to 22 are provided, and the switches 19 to 22
The same effect can be obtained by selectively switching. In the case of the second embodiment, as in the case of the first embodiment, the direct current can be cut off regardless of the direction of the load current, and the changeover switch section can be downsized.

The operation of the circuit shown in FIG. 2 will be described. In the case of the second embodiment, the rectifying element 5 provided in the DC cutoff section
Is not a complete unidirectional rectifying element such as a diode, but an element such as a saturable reactor that has bidirectional current carrying capability and maintains a rectifying function for a certain period (a period corresponding to V / S of the reactor). Is.

When current is flowing in the load coil 2 in the direction A, when a quench or the like occurs, the cutoff switch 4 of the DC cutoff unit is turned on, and at the same time, the changeover switch selection unit is generated by the detection signal from the current detection unit 17. 18 selects the switch to be turned on and turns on the changeover switches 21 and 22.
After that, the DC power supply 1 shifts to the operation of inverting the output voltage, and the load current is returned to the load through the DC cutoff unit including the cutoff switch 4, the rectifying element 5, and the commutation circuit 6. After the load current is commutated to the DC cutoff unit, the DC power supply 1 is disconnected as in the first embodiment.

Next, in order to cut off the current flowing through the breaking switch 4, a current flows from the capacitor 7 of the commutation circuit 6 in a direction opposite to the current flowing through the breaking switch 4, and the current of the breaking switch 4 is kept for a certain period. The cutoff switch 4 is opened as zero.

When a current or the like flows in the load coil 2 in the direction B, when a quench or the like occurs, the changeover switch selection unit 18 selects the switch to be turned on by the detection signal from the current detection unit 17, and the DC cutoff unit is activated. At the same time as the breaking switch 4 is turned on, the changeover switches 19 and 20 are turned on.
The subsequent operation is the same as when the changeover switches 21 and 22 are turned on, but the direction of the current flowing through the DC cutoff portion is opposite to that when the changeover switches 21 and 22 are turned on.

When a supersaturated reactor is used as the rectifying element 5, since the supersaturated reactor can be energized in both directions in the steady energized state, it is possible to pass a current in both directions through the cutoff switch 4. Therefore, by changing the energizing direction of the current from the commutation circuit 6 with the change-over switches 19 to 22, it is possible to make the breaker switch 4 have a period in which the current becomes zero regardless of the direction of the current.

In the second embodiment described above, the breaking switch 4 is opened without arcing when the direct current is cut off. However, as shown in FIG. Although an arc is generated, the same effect can be achieved. Further, in FIG. 2, the cutoff switch 4, the rectifying element 5,
A direct current cut-off portion composed of a commutation circuit 6 and a cut-off resistance 10;
Although the DC power supply 1 and the load coil 2 are connected in parallel, the same effect can be obtained when they are connected in series. Further, as shown in FIG. 7, a changeover signal of the changeover switch may be inputted from the outside.

[Third Embodiment] FIG. 3 shows a third embodiment of the DC circuit breaker according to the present invention. In the third embodiment, the voltage of the capacitor 7 of the commutation circuit 6 is charged or discharged in accordance with the current value flowing in the load coil 2, and the reverse of the current value matched with the load current even when the load current changes. The current is passed through the cutoff switch 4 so as to be cut off.

The operation of the circuit shown in FIG. 3 will be described. DC power supply 1
Therefore, it is assumed that the load coil 2 is energized while changing the current value at a certain cycle T. The current detection unit 17 detects the value of the output current or the load current of the DC power supply 1, and sends it to the charge / discharge control unit 23. The charge / discharge control unit 23 uses this detection output and the charging voltage of the capacitor 7 to perform a predetermined calculation. Done,
The voltage of the commutation circuit 6 is controlled by charging and discharging the capacitor 7.

When a quench or the like occurs in the load coil 2, the cutoff switch 4 is turned on. As a result, the load current is commutated to the cutoff switch 4, and the DC power supply 1 is disconnected. In this state, the capacitor 7 of the commutation circuit 6 is
The charging / discharging control unit 23 controls the voltage value corresponding to the load current at the time of occurrence of quench. Therefore, when the commutation circuit 6 is turned on, the current of the cutoff switch 4 becomes zero,
Current interruption is realized.

The third embodiment has shown the example in which the cutoff switch 4 and the commutation circuit 6 are directly connected to the load coil 2.
If the changeover switch is used to switch between positive and negative, it can be applied even when the load current is reversed. Further, as shown in FIG. 9, a rectifying element 5 may be inserted in series in the breaking switch 4, and when the change in the load current is not periodic, the breaking switch 4 in FIG. The same effect can be obtained by connecting the DC cutoff unit composed of 6 in series with the DC power supply 1 and the load coil 2.

[Fourth Embodiment] FIG. 4 shows a fourth embodiment of the DC circuit breaker according to the present invention. In the fourth embodiment, when the breaking switch 4 is opened and current is flowing in the breaking switch 4, the protective fuse 25 is turned on to divert the current to the protective fuse 25 side, and the protective fuse 25 is blown. By doing so, the interruption is performed.

The operation of the circuit shown in FIG. 4 will be described. DC power supply 1
If a quench or the like occurs in the load coil 2 while a current is being applied to the load coil 2, the cutoff switch 4 is turned on. The DC power supply 1 inverts the voltage to transfer the load current to the cutoff switch 4, and then is disconnected by the switch 3. Then, after the load current commutates to the cutoff switch 4,
A current in the direction opposite to the load current is fed from the commutation circuit 6,
The breaker switch 4 is opened by setting the current to zero.

In the above breaking operation, the breaking switch 4
If the breaking switch 4 is opened at this time due to the jitter or operation delay, the breaking switch 4 current will flow again from zero, and the breaking switch 4 will generate an arc and cannot break the current. In this case, the circuit of FIG. 4 detects the current of the breaking switch 4 by the current detecting unit 26, and when the current starts to flow again from zero, the breaking judgment unit 27 judges that the breaking has failed, and the protective fuse closing switch 24 Throw in.

When the protective fuse closing switch 24 is turned on, the current flowing through the breaking switch 4 is commutated to the protective fuse 25 side by the arc voltage generated by the breaking switch 4. As a result, the arc of the breaking switch 4 is extinguished, and the contact opening is completed. After that, the protective fuse 25
Is melted by the commutated current, and the cutoff of the direct current is completed.

In the fourth embodiment, the DC cutoff unit composed of the cutoff switch 4 and the commutation circuit 6 is connected to the DC power supply 1 and the load coil 2.
Although the case where they are connected in parallel is shown, the same effect can be obtained when they are connected in series. Further, as shown in FIG. 10, when the rectifying element 5 is located outside the protective fuse 25 and the rectifying element 5 is inserted in series with the cutoff switch 4, the same effect can be obtained.

As shown in FIG. 11, it is also possible to externally input a closing command of the protective fuse closing switch 24. Further, as shown in FIG.
The voltage detection unit 28 may detect the voltage across the disconnection switch 4 to detect failure of the disconnection.

[0043]

According to the first DC circuit breaker of the present invention, the connection direction of the breaking switch and the commutation circuit is switched between positive and negative depending on the direction of the current flowing from the DC power source to the load. It is possible to break with one breaker regardless of the direction of the current flowing through.

According to the second DC circuit breaker of the present invention, the connection direction of the commutation circuit to the load is switched between positive and negative in accordance with the direction of the current flowing from the DC power supply to the load. It is possible to break with a single breaker regardless of the direction of.

According to the third DC circuit breaker of the present invention, the charging voltage of the capacitor of the commutation circuit is controlled by charging or discharging according to the load current, and the load is changed even when the load current changes. Since the reverse current of the current value matching the current is made to flow through the cutoff switch, it is possible to cut off even when the current flowing through the load is not only direct current but also varying current such as triangular wave.

According to the fourth DC circuit breaker of the present invention, the protective fuse is connected in parallel to the breaking switch so that when the current is flowing through the breaking switch, the protective fuse is diverted to the protective fuse to protect it. Since the current is cut off when the fuse is blown, even if the cutoff switch fails to cut off, the protection fuse can surely cut off the current.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a sixth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 8 is a circuit diagram showing an eighth embodiment of the present invention.

FIG. 9 is a circuit diagram showing a ninth embodiment of the present invention.

FIG. 10 is a circuit diagram showing a tenth embodiment of the present invention.

FIG. 11 is a circuit diagram showing an eleventh embodiment of the present invention.

FIG. 12 is a circuit diagram showing a twelfth embodiment of the present invention.

FIG. 13 is a circuit diagram showing a conventional DC circuit breaker.

FIG. 14 is an operation waveform diagram of a conventional DC circuit breaker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Load 4 Breaking switch 5 Rectifying element 6 Commutation circuit 7 Capacitor 8 Reactor 13-16 Changeover switch 17 Current detection part 18 Changeover switch selection part 19-22 Changeover switch 23 Charge / discharge control part 24 Protection fuse closing switch 25 Protection Fuse 26 Current detector 27 Break judgment unit

Claims (8)

[Claims] 1. A breaking switch, which is located between a DC power source and a load and is connected in parallel to the load, and a commutation circuit connected in parallel to the breaking switch, wherein the commutation circuit is at least in series. A direct current circuit breaker comprising a connected capacitor and a reactor, in which an LC resonance current generated by the capacitor and the reactor cancels a current flowing through the cutoff switch, wherein a load depending on a direction of a current flowing from the direct current power supply to the load. A DC circuit breaker is provided with switch means for switching the connection direction of the cutoff switch and the commutation circuit between positive and negative. 2. A commutation circuit connected between the DC power source and the load and connected in parallel or in series to the load, and a commutation circuit connected in parallel to the interruption switch, the commutation circuit comprising: An LC including at least a capacitor and a reactor connected in series, the LC including the capacitor and the reactor.
In a DC circuit breaker configured to cancel a current flowing through the breaking switch by a resonance current, a changeover switch is provided to switch the connection direction of the commutation circuit to the load depending on the direction of the current flowing from the DC power source to the load. A DC circuit breaker characterized by the above. 3. A commutation circuit connected between the DC power source and the load and connected in parallel or in series to the load, and a commutation circuit connected in parallel to the interruption switch, the commutation circuit comprising: An LC including at least a capacitor and a reactor connected in series, the LC including the capacitor and the reactor.
A DC circuit breaker configured to cancel a current flowing through the cutoff switch by a resonance current, characterized in that a charging / discharging control means for controlling a charging voltage of a capacitor of the commutation circuit according to a load current is provided. Circuit breaker. 4. A breaking switch which is located between a DC power source and a load and which is connected in parallel or in series to the load, and a commutation circuit which is connected in parallel to the breaking switch. An LC including at least a capacitor and a reactor connected in series, the LC including the capacitor and the reactor.
A DC circuit breaker configured to cancel a current flowing through the breaking switch by a resonance current, characterized in that a protective fuse and a protective fuse closing switch for connecting and closing the protecting fuse in parallel with the breaking switch are provided. DC circuit breaker. 5. The DC circuit breaker according to claim 1, further comprising switch selection means for detecting a direction of a current flowing from the DC power supply to the load and selecting a switching direction of the changeover switch. 6. The DC circuit breaker according to claim 4, further comprising a cutoff judging means for detecting a current flowing through the cutoff switch to judge a cutoff failure, and for instructing a closing timing of the protective fuse closing switch. 7. The DC circuit breaker according to claim 4, further comprising a cutoff determining unit that detects a voltage across the cutoff switch to determine a cutoff failure and indicates a closing timing of the protective fuse closing switch. 8. The DC circuit breaker according to claim 1, further comprising a rectifying element in series with the cutoff switch.