JP6919497B2 - DC cutoff device - Google Patents

Description

The present invention relates to a DC cutoff device.

7 and 8 are circuit configuration diagrams showing an example of a conventional DC cutoff device. Unlike alternating current, direct current does not generate a zero, so there is the problem that the arc generated when the mechanical circuit breaker is opened cannot be extinguished. The DC circuit breaker shown in FIGS. 7 and 8 creates a zero point in the current flowing through the mechanical circuit breakers CB1, CB2 and CB by bypassing the current at the time of opening the mechanical circuit breakers CB1, CB2 and CB to the auxiliary circuit. Extinguish the arc.

The DC circuit breaker of FIG. 7 has two mechanical circuit breakers CB1 and CB2, one resonance capacitor C and switching elements T1 and T2, and the DC circuit breaker of FIG. 8 has one mechanical circuit breaker CB and 2 It has a stand of resonant capacitors C1 and C2 and switching elements T1 and T2, both of which have a bidirectional current cutoff function. A gate drive circuit (not shown) is connected to each of the switching elements of FIGS. 7 and 8. The power supply of each gate drive circuit is supplied from the outside.

FIG. 9 is a circuit configuration diagram of the AC cutoff device in Patent Document 1. The AC cutoff device of Patent Document 1 detects the system current with the current transformer 18, and inputs the secondary side current of the current transformer 18 to the gate terminal of the switching element. Patent Document 1 is characterized in that it does not require a power supply for driving a gate of a switching element.

Japanese Unexamined Patent Publication No. 09-274833

As shown in FIGS. 7 and 8, the DC cutoff device separately requires an independent power supply for driving the gate of the switching element. Further, it is necessary to separately input a gate control signal, which is an on / off command signal of the switching element, from an external control device. Therefore, the number of parts and the cost of the DC cutoff device shown in FIGS. 7 and 8 increase.

Since Patent Document 1 is an alternating current blocking device, it cannot cut off a direct current. Further, although the power supply for driving the gate of the switching element can be generated by the current transformer 18, the gate control signal which is the on / off command signal of the switching element needs to be separately input from the external control device 23. If noise is superimposed on this gate control signal, the switching element may malfunction.

From the above, it is a problem that the DC cutoff device does not require an independent power supply for driving the gate of the switching element and a gate control signal from the outside.

The present invention has been devised in view of the above-mentioned conventional problems, and one aspect thereof is a first mechanical breaker connected between the positive electrode of the first direct current system and the positive electrode of the second direct current system. A third diode in which an anode terminal is connected to a common connection point between the positive electrode of the first DC system and the first mechanical breaker, and a first switching element in which a collector terminal is connected to the cathode terminal of the third diode. The LC circuit connected between the common connection point of the first mechanical breaker and the positive electrode of the second DC system and the emitter terminal of the first switching element, the emitter terminal of the first switching element, and the first , A third resistor connected between the negative electrode of the second DC system, a first resistor having one end connected between the positive electrode of the first DC system and the first mechanical breaker, and the first resistor. A first capacitor connected between the other end of the resistor and the negative electrode of the first and second DC systems, a common connection point between the first resistor and the first capacitor, and a positive electrode of the first DC system. When the second resistor and the second diode connected in series with the common connection point of the first mechanical breaker and the primary side detect the passing current of the second resistor, the secondary side is the first switching. A first current converter that outputs a current to the gate terminal of the element, a third capacitor connected between the gate terminal and the emitter terminal of the first switching element, and a fourth capacitor connected in parallel to the third capacitor. It is characterized by having resistance.

Further, as another embodiment, the first mechanical breaker connected between the positive electrode of the first DC system and the positive electrode of the second DC system, and the positive electrode of the first DC system and the first mechanical breaker are common. A third diode with an anode terminal connected to the connection point, a first switching element with a collector terminal connected to the cathode terminal of the third diode, and a common commonality between the first mechanical breaker and the positive electrode of the second DC system. A third LC circuit connected between the connection point and the emitter terminal of the first switching element, and a third connected between the emitter terminal of the first switching element and the negative electrode of the first and second DC systems. A resistor, a first resistor having one end connected between the positive electrode of the second DC system and the first mechanical breaker, the other end of the first resistor, and the negative electrode of the first and second DC systems. In series between the first capacitor connected between the above, the common connection point of the first resistor and the first capacitor, and the common connection point of the positive electrode of the first DC system and the first mechanical breaker. The 5th and 6th resistors connected in series between the connected 2nd resistor and 2nd diode, the common connection point of the 1st resistor and the 1st capacitor, and the negative electrode of the 1st and 2nd DC systems. And the eighth resistor and the first switch connected in series between the common connection point between the positive electrode of the first DC system and the first mechanical breaker and the common connection point of the fifth and sixth resistors. The fourth capacitor connected between the common connection point of the fifth and sixth resistors and the negative electrode of the first and second DC systems, and the seventh resistor and the seventh resistor connected in parallel to the fourth capacitor. The two coils, the first current transformer that outputs a current to the gate terminal of the first switching element when the primary side detects the passing current of the second resistance, and the gate terminal of the first switching element. A third capacitor connected between the and the emitter terminal and a fourth resistor connected in parallel to the third capacitor are provided, and the second coil is an operating coil of the first mechanical breaker. The first mechanical breaker is closed when a predetermined current flows through the second coil.

Further, as another embodiment, a first mechanical circuit breaker and a second mechanical circuit breaker connected between the positive electrode of the first DC system and the positive electrode of the second DC system, the first mechanical circuit breaker and the second mechanical circuit breaker. An LC circuit and a third resistor sequentially connected in series between the mechanical circuit breaker and the negative electrode of the first and second DC systems, and a common connection between the positive electrode of the first DC system and the first mechanical circuit breaker. A first switching element in which a third diode with an anode terminal connected to a point, a collector terminal connected to the cathode terminal of the third diode, and an emitter terminal connected to a common connection point between the LC circuit and the third resistor. A sixth diode having an anode terminal connected to a common connection point between the positive electrode of the second DC system and the second mechanical circuit breaker, and a collector terminal connected to the cathode terminal of the sixth diode, and the LC circuit. A second switching element in which an emitter terminal is connected to a common connection point of the third resistor, and a first resistor in which one end is connected to a common connection point between the positive electrode of the first DC system and the first mechanical circuit breaker. , The first capacitor connected between the other end of the first resistor and the negative electrode of the first and second DC systems, the common connection point between the first resistor and the first capacitor, and the first DC. When the second switch, the second resistor and the second diode connected in series between the positive electrode of the system and the common connection point of the first mechanical circuit breaker, and the primary side detect the passing current of the second resistor. A first circuit breaker whose secondary side outputs a current to the gate terminal of the first switching element, a third capacitor connected between the gate terminal and the emitter terminal of the first switching element, and the third A fourth resistor connected in parallel to the capacitor, a ninth resistor one end connected to a common connection point between the positive electrode of the second DC system and the second mechanical circuit breaker, and the other end of the ninth resistor. A fifth capacitor connected between the first and second DC systems, a common connection point between the ninth resistor and the fifth capacitor, a positive circuit breaker of the second DC system, and the second machine. When the third switch, the tenth resistor and the fifth diode connected in series between the common connection point of the circuit breaker and the passing current of the tenth resistor are detected by the primary side, the secondary side is the second switching. A second circuit breaker that outputs a current to the gate terminal of the element, a sixth capacitor connected between the gate terminal and the emitter terminal of the second switching element, and a sixth capacitor connected in parallel to the sixth capacitor. With an eleventh resistor, a current is flowing from the first DC system to the second DC system. When the time is, the second switch is turned on, the third switch is turned off, and when the current is flowing from the second DC system to the first DC system, the second switch is turned off and the third switch is turned on. It is characterized by doing.

According to the present invention, in the DC cutoff device, it is possible to eliminate the need for an independent power supply for driving the gate of the switching element and a gate control signal from the outside.

The circuit block diagram which shows the DC cutoff device in Embodiment 1. FIG. The figure which shows the steady state of the DC cutoff device in Embodiment 1. FIG. The figure which shows the cut-off state of the DC cut-off device in Embodiment 1. FIG. The figure which shows the state after the mechanical circuit breaker arc extinguishing of the DC circuit breaker in Embodiment 1. FIG. The circuit block diagram of the DC cutoff device in Embodiment 2. The circuit block diagram of the DC cutoff device in Embodiment 3. The circuit block diagram which shows an example of the conventional DC cutoff device. The circuit block diagram which shows the other example of the conventional DC cutoff device. The circuit block diagram which shows the AC cutoff device of Patent Document 1. FIG.

Hereinafter, embodiments 1 to 3 of the DC blocking device according to the present invention will be described in detail with reference to FIGS. 1 to 6.

[Embodiment 1]
FIG. 1 shows a DC cutoff device according to the first embodiment. In the DC circuit breaker of the first embodiment, the first mechanical circuit breaker CB1 is connected between the positive electrode of the first DC system 1 and the positive electrode of the second DC system 2.

One end of the first resistor R1 is connected between the positive electrode of the first DC system 1 and the first mechanical circuit breaker CB1. The first capacitor C1 is connected between the other end of the first resistor R1 and the negative electrode of the first and second DC systems 1 and 2.

The second resistor R2 and the second diode D2 are connected in series between the common connection point of the first resistor R1 and the first capacitor C1 and the common connection point of the positive electrode of the first DC system 1 and the first mechanical circuit breaker CB1. Will be done. The anode terminal of the second diode D2 is connected to the second resistor R2, and the cathode terminal is connected to the common connection point of the positive electrode of the first DC system 1 and the first mechanical circuit breaker CB1.

One end of the first reactor L1 is connected between the first mechanical circuit breaker CB1 and the positive electrode of the second DC system 2. One end of the second capacitor C2 is connected to the other end of the first reactor L1. The LC circuit is composed of the first reactor L1 and the second capacitor C2. A third resistor R3 is connected between the other end of the second capacitor C2 and the negative electrode of the first and second DC systems 1 and 2.

The anode terminal of the third diode D3 is connected between the positive electrode of the first DC system 1 and the first mechanical circuit breaker CB1. The collector terminal of the first switching element T1 is connected to the cathode terminal of the third diode D3. The emitter terminal of the first switching element T1 is connected to a common connection point between the second capacitor C2 and the third resistor R3. In this way, the first switching element T1 is connected in parallel to the first mechanical circuit breaker CB1.

The primary side of the first current transformer CT1 detects the passing current of the second resistor R2. Therefore, the primary side of the first transformer CT1 has a common connection point between the positive electrode of the first DC system 1 and the cathode of the second diode D2 and a common connection point between the first resistor R1 and the first capacitor C1. It is inserted in a path consisting of a series circuit of a second diode D2 and a first resistor R1 connecting between them.

The first Zener diode ZD1 is connected between one end and the other end of the secondary side of the first current transformer CT1. The emitter terminal of the first switching element T1 is connected to one end on the secondary side of the first current transformer CT1. The anode terminal of the fourth diode D4 is connected to the other end of the secondary side of the first current transformer CT1. The cathode terminal of the fourth diode D4 is connected to the gate terminal of the first switching element T1.

A third capacitor C3 is connected between the gate terminal and the emitter terminal of the first switching element T1. The fourth resistor R4 is connected in parallel to the third capacitor C3.

FIG. 2 shows a steady state of the DC cutoff device according to the first embodiment. It is assumed that the first mechanical circuit breaker CB1 is in a closed pole state, and the current flows only in one direction (first DC system 1 → second DC system 2). In the first embodiment, only unidirectional blocking is possible.

At this time, a charging current flows through the first capacitor C1 via the first resistor R1. Further, a charging current flows through the second capacitor C2 via the third resistor R3 and the first reactor L1. The dotted line in FIG. 2 is the charging current path.

The current passes through the first mechanical breaker CB1 and the first resistor R1, the first reactor L1, and the third resistor R3, but when the charging of the first and second capacitors C1 and C2 is completed (that is, the first and first ones). (When the voltage of the two capacitors C1 and C2 becomes the same value as the voltage of the first DC system 1), no current flows through the first resistor R1 and the third resistor R3. Therefore, no power loss occurs in the first resistor R1 and the third resistor R3. Further, the resistance between the two poles when the first mechanical circuit breaker CB1 is closed is very small. Therefore, when the first mechanical circuit breaker CB1 is closed, there is almost no power loss generated in the first mechanical circuit breaker CB1.

FIG. 3 shows the DC cutoff device of the first embodiment when a short circuit accident occurs on the second DC system 2 side. When a short-circuit accident occurs, the voltage of the second DC system 2 drops, so the charge of the first capacitor C1 is discharged to the first and second DC systems 1 and 2 through the second resistor R2 → the second diode D2. NS. This discharge current is detected by the primary side of the first current transformer CT1.

A current is output from the secondary side of the first transformer CT1, and the fourth diode D4 → the gate capacitance of the first switching element T1 (the capacitance between the gate terminal and the emitter terminal of the first switching element T1) and the third capacitor C3. The gate capacitance of the third capacitor C3 and the first switching element T1 (the capacitance between the gate terminal and the emitter terminal of the first switching element T1) is charged, and the gate voltage of the first switching element T1 (that is, the third capacitor) is charged. The C3 applied voltage) becomes the turn ON level, and the first switching element T1 is turned ON.

When the gate voltage rises to the breakdown voltage of the first Zener diode ZD1 after the first switching element T1 is turned on, the output current uses the first Zener diode ZD1 instead of the gate capacitance of the first switching element T1 and the third capacitor C3. It passes through and prevents overcharging of the gate of the first switching element T1.

After the first switching element T1 is turned on, the discharge current from the second capacitor C2 flows through the first reactor L1 → the first mechanical circuit breaker CB1 → the third diode D3 → the first switching element T1. The short-circuit current flowing from the DC system 1 to the first mechanical circuit breaker CB1 is canceled. When this short-circuit current becomes small, the first mechanical circuit breaker CB1 is opened by an opening / closing command signal from the outside. The reduction in the short-circuit current is determined from the output value of the current detector (not shown) connected in series with the first mechanical circuit breaker CB1.

FIG. 4 shows a DC circuit breaker after opening the first mechanical circuit breaker CB1. After opening the first mechanical circuit breaker CB1, a short-circuit current flows through the third diode D3 → the first switching element T1 → the second capacitor C2 → the first reactor L1, and the second capacitor C2 is charged in the opposite polarity. ..

When the charging of the second capacitor C2 is completed (when the voltage of the second capacitor C2 becomes the same value as the voltage of the first DC system 1), the current flowing to the second DC system 2 becomes zero, and the current cutoff is completed.

When the current cutoff is completed and the discharge of the first capacitor C1 is completed, the detection current of the first current transformer CT1 becomes zero, and the output current on the secondary side of the first current transformer CT1 also becomes zero. Therefore, the gate capacitance of the first switching element T1 and the electric charge charged in the third capacitor C3 are discharged through the fourth resistor R4.

As the discharge progresses, the gate voltage of the first switching element T1 (that is, the applied voltage of the first capacitor C1) drops to the turn-off level, and the first switching element T1 turns off. After that, the first capacitor C1 is recharged to the voltage of the first DC system 1 via the first resistor R1 → the first capacitor C1.

When the system is restarted after eliminating the short-circuit factor on the second DC system 2 side by the restoration work after opening the first mechanical circuit breaker CB1, first, the first mechanical circuit breaker CB1 is closed by an open / close command signal from the outside. Extreme. As a result, a current flows from the first DC system 1 side to the second DC system 2 side via the first mechanical circuit breaker CB1.

Further, a charging current flows through the first mechanical circuit breaker CB1 → the first reactor L1 → the second capacitor C2 → the third resistor R3, and the second capacitor C2 charged in the opposite polarity is recharged to the original polarity. .. When charging is completed, the state shown in FIG. 2 is reached and re-loading is completed. The same operation is performed in the third embodiment, which will be described later.

The design precautions for the DC circuit breaker device of the first embodiment will be described.

The capacitance of the first capacitor C1 is sufficient to turn on the gate of the first switching element T1 when a short circuit occurs. The third capacitor C3 is for preventing an erroneous ignition of the gate of the first switching element T1. The first switching element T1 is prevented from being turned ON in response to a system voltage fluctuation within a normal range.

The first Zener diode ZD1 is for preventing gate overcharging. For example, if the first switching element T1 is an IGBT having a rated gate voltage ON voltage = 15V, a Zener diode having a yield voltage of 15V is used.

The first resistor R1 limits the current during charging of the first capacitor C1. The second resistor R2 determines the magnitude and discharge time of the discharge current of the first capacitor C1 when a short-circuit accident occurs. In order to detect this discharge current with the first current transformer CT1, the second resistor R2 must be designed so that a current sufficient to turn on the first switching element T1 flows on the secondary side of the first current transformer CT1. Must be.

It is necessary to pass a sufficient current on the secondary side of the first current transformer CT1 to drive the gate of the first switching element T1. It is necessary to determine the turns ratio of the first current transformer CT1 (that is, the current transformer ratio of the first current transformer CT1) from the value of the passing current of the second resistor R2.

After a short circuit occurs in the second DC system 2 and the first mechanical circuit breaker CB1 is opened, the turn-off speed of the first switching element T1 is the discharge speed of the gate, that is, the third capacitor C3 and the fourth resistor R4. It depends on the time constant. During the shutoff operation of the first mechanical circuit breaker CB1, the first switching element T1 can be kept ON, and after the shutoff of the first mechanical circuit breaker CB1 is completed, the first switching element T1 is turned off with the third capacitor C3. Design the time constant of the 4th resistor R4.

As shown above, unlike the DC cutoff device shown in FIGS. 7 and 8, the present embodiment 1 does not require a power supply for driving the gate of the first switching element T1, so that the DC cutoff device is downsized and low in cost. Can be converted.

Further, unlike Patent Document 1, it is not necessary to input the gate signal for the first switching element T1 from the outside, and the control device 23 shown in FIG. 9 is unnecessary. Since no control device is required, it is possible to reduce the size and cost of the DC cutoff device.

Further, since it is not necessary to input the gate signal for the first switching element T1 from the outside, there is no possibility that noise is superimposed on the signal input from the outside and the first switching element T1 malfunctions. This improves the reliability of the DC cutoff device.

Further, the DC circuit breaker of the first embodiment causes a power loss because the current passes through the first mechanical circuit breaker CB1 having a very small resistance after the charging of the first and second capacitors C1 and C2 is completed in the steady state. It is possible to reduce it.

[Embodiment 2]
FIG. 5 is a circuit configuration diagram showing a DC cutoff device according to the second embodiment. The same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

One end of the first resistor R1 connected to the first DC system 1 side is connected to a common connection point between the first mechanical circuit breaker CB1 and the positive electrode of the second DC system 2. The first capacitor C1 is connected between the other end of the first resistor R1 and the negative electrode of the first and second DC systems 1 and 2.

The anode terminal of the first diode D1 is connected to the common connection point of the first resistor R1 and the first capacitor C1. The fifth and sixth resistors R5 and R6 are connected in series between the cathode terminal of the first diode D1 and the negative electrodes of the first and second DC systems 1 and 2.

One end of the eighth resistor R8 is connected between the positive electrode of the first DC system 1 and the first mechanical circuit breaker CB1. The first switch SW1 is connected between the other end of the eighth resistor R8 and the common connection point of the fifth and sixth resistors R5 and R6. The first switch SW1 is a mechanical switch and is manually switched on and off.

The fourth capacitor C4 is connected between the common connection points of the fifth and sixth resistors R5 and R6 and the negative electrodes of the first and second DC systems 1 and 2. A series circuit of the seventh resistor R7 and the second coil L2 is connected in parallel to the fourth capacitor C4. When a current flows through the second coil L2, the contacts of the first mechanical circuit breaker CB1 are closed. In the second embodiment, a circuit for opening the first mechanical circuit breaker CB1 is added to the first embodiment. Is. Hereinafter, the opening / closing operation of the first mechanical circuit breaker CB1 will be described.

To return to the normal state in which current flows from the first DC system 1 side to the second DC system 2 side from the state in which the first mechanical circuit breaker CB1 is open, manually press the first switch SW1 after the system is turned on. Turn on. By this operation, the fourth capacitor C4 is charged via the eighth resistor R8, a current flows through the second coil L2 of the first mechanical circuit breaker CB1, and the first mechanical circuit breaker CB1 is closed.

Next, after confirming that the first mechanical circuit breaker CB1 is closed, the first switch SW1 is manually turned off. When the first mechanical circuit breaker CB1 is closed, the fourth capacitor C4 is charged from the second DC system 2 side via the first resistor R1 → the first diode D1 → the fifth resistor R5. Therefore, even if the first switch SW1 is turned off, the current flows through the second coil L2 of the first mechanical circuit breaker CB1, so that the closed state of the first mechanical circuit breaker CB1 is maintained.

When a short-circuit accident occurs on the second DC system 2 side, the operation is as follows in parallel with the operation described in the first embodiment.

The voltage of the second DC system 2 drops, the charge of the first capacitor C1 is discharged, the anode of the first diode D1 becomes low potential, and the first diode D1 is cut off. Therefore, the charge of the fourth capacitor C4 Is discharged via the sixth resistor R6. When the discharge of the fourth capacitor C4 is completed and the voltage of the fourth capacitor C4 becomes zero, the current flowing through the second coil L2 becomes zero and the first mechanical circuit breaker CB1 opens.

The time from the occurrence of an accident on the second DC system 2 side to the opening of the first mechanical circuit breaker CB1 is determined by the time constants of the sixth resistor R6 and the fourth capacitor C4. It is necessary to design the time constants of the sixth resistor R6 and the fourth capacitor C4 so that the first mechanical circuit breaker CB1 can be opened when the short-circuit current becomes sufficiently small.

In the second embodiment, the first switch SW1 has been described as a manual switch. This manual switch generates an open / close command signal for the first switch SW1 according to the normal / abnormal state of the DC system and the open / close state of the first mechanical circuit breaker CB1, and opens / closes the first switch SW1 according to the open / close command signal. It may be replaced with an automatic switch to make it.

As shown above, according to the second embodiment, the same effects as those of the first embodiment are obtained. Further, in the second embodiment, as compared with the first embodiment and the third embodiment described later, it is not necessary to input the opening / closing command signal of the first mechanical circuit breaker CB1 from the outside, and the system configuration is simplified.

[Embodiment 3]
FIG. 6 is a circuit diagram showing a DC cutoff device according to the third embodiment. The same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The second switch SW2 is connected between the first and second resistors R1 and R2. The second switch SW2 is a mechanical switch.

The circuit excluding the first reactor L1, the second capacitor C2, and the third resistor R3 from the circuit of FIG. 1 is arranged so as to be line-symmetrical with respect to the first reactor L1, the second capacitor C2, and the third resistor R3. ..

Specifically, the second mechanical circuit breaker CB2 is connected between the common connection point of the first mechanical circuit breaker CB1 and the first reactor L1 and the positive electrode of the second DC system 2. One end of the ninth resistor 9 is connected between the positive electrode of the second DC system 2 and the second mechanical circuit breaker CB2. The fifth capacitor C5 is connected between the other end of the ninth resistor R9 and the negative electrode of the first and second DC systems 1 and 2.

Between the common connection point of the 9th resistor R9 and the 5th capacitor C5 and the common connection point of the positive electrode of the 2nd DC system 2 and the 2nd mechanical circuit breaker CB2, the 3rd switch S3 and the 10th resistor R10 and the 5th The diode D5 is connected in series.

The anode terminal of the sixth diode D6 is connected to the common connection point between the positive electrode of the second DC system 2 and the second mechanical circuit breaker CB2. The collector terminal of the second switching element T2 is connected to the cathode terminal of the sixth diode D6. The emitter terminal of the second switching element T2 is connected to a common connection point between the second capacitor C2 and the third resistor R3.

In the second current transformer CT2, the primary side detects the passing current of the tenth resistor R10, and the secondary side outputs the current to the gate terminal of the second switching element. A second Zener diode ZD2 is connected between one end and the other end of the second current transformer CT2. The emitter terminal of the second switching element T2 is connected to one end on the secondary side of the second current transformer CT2. The anode terminal of the 7th diode D7 is connected to the other end of the secondary side of the second current transformer CT2. The cathode terminal of the seventh diode D7 is connected to the gate terminal of the second switching element T2.

A sixth capacitor C6 is connected between the gate terminal and the emitter terminal of the second switching element T2. The 11th resistor R11 is connected in parallel with the 6th capacitor C6.

The third embodiment is a circuit for dealing with bidirectional current interruption. When the current is flowing from the first DC system 1 to the second DC system 2, the second switch SW2 is turned on and the third switch SW3 is turned off. On the contrary, when a current is flowing from the second DC system 2 to the first DC system 1, the second switch SW2 is turned off and the third switch SW3 is turned on.

The direction of the current is separately detected by a detector, and the first and second switches SW1 and SW2 are turned ON and OFF by an external command according to the direction of the detected current. In the normal state, both the first and second mechanical circuit breakers CB1 and CB2 are closed by an external closing command regardless of the direction of the current.

If a short-circuit accident occurs on the 2nd DC system 2 side while the current is flowing from the 1st DC system 1 to the 2nd DC system 2 (2nd switch SW2 is ON, 3rd switch SW3 is OFF), the 3rd switch Since SW3 is OFF, the fifth capacitor C5 is not discharged and the second switching element T2 is not ON. That is, since the resonance circuit for opening the second mechanical circuit breaker CB2 pole does not function, the operation is the same as that of the first embodiment.

If a short-circuit accident occurs on the 1st DC system 1 side while the current is flowing from the 2nd DC system 2 to the 1st DC system 1, the circuit (2nd switch SW2 is OFF, 3rd switch SW3 is ON) Since it is symmetrical, the operation is the same as in the case of a short-circuit accident on the 2nd DC system 2 side.

Further, when a short-circuit accident occurs and the flow is flowing from the first DC system 1 to the second DC system 2, the first mechanical circuit breaker CB1 is opened by an external first mechanical circuit breaker CB1 opening command. When flowing from the second DC system 2 to the first DC system 1, the second mechanical circuit breaker CB2 is opened by the second mechanical circuit breaker CB2 opening command from the outside. The opening of the first mechanical circuit breaker CB1 (or the second mechanical circuit breaker CB2) is a short-circuit current flowing through the first mechanical circuit breaker CB1 (or the second mechanical circuit breaker CB2) as in the first embodiment. Do this when becomes smaller.

Then, after eliminating the short-circuit factor on the first DC system 1 side or the second DC system 2 side, both the first and second mechanical circuit breakers CB1 and CB2 are closed by an external closing command.

As shown above, according to the third embodiment, the same effects as those of the first embodiment are obtained. Further, in the third embodiment, bidirectional current interruption is possible.

Although the above description has been made in detail only with respect to the specific examples described in the present invention, it is clear to those skilled in the art that various modifications and modifications can be made within the scope of the technical idea of the present invention. It goes without saying that such modifications and modifications fall within the scope of the claims.

CB1, CB2 ... 1st and 2nd mechanical circuit breakers T1, T2 ... 1st and 2nd switching elements CT1, CT2 ... 1st and 2nd current transformers R1 to R11 ... 1st to 11th resistors C1 to C6 ... 1st 1st to 6th capacitors L1, L2 ... 1st and 2nd reactors D1 to D7 ... 1st to 7th diodes ZD1, ZD2 ... 1st and 2nd Zener diodes SW1 to SW3 ... 1st to 3rd switches

Claims (3)

A first mechanical circuit breaker connected between the positive electrode of the first DC system and the positive electrode of the second DC system,
A third diode having an anode terminal connected to a common connection point between the positive electrode of the first DC system and the first mechanical circuit breaker,
A first switching element in which a collector terminal is connected to the cathode terminal of the third diode, and
An LC circuit connected between the common connection point of the first mechanical circuit breaker and the positive electrode of the second DC system and the emitter terminal of the first switching element.
A third resistor connected between the emitter terminal of the first switching element and the negative electrode of the first and second DC systems, and
A first resistor having one end connected between the positive electrode of the first DC system and the first mechanical circuit breaker,
A first capacitor connected between the other end of the first resistor and the negative electrode of the first and second DC systems,
A second resistor and a second diode connected in series between the common connection point of the first resistor and the first capacitor, and the common connection point of the positive electrode of the first DC system and the first mechanical circuit breaker. ,
When the primary side detects the passing current of the second resistor, the secondary side outputs the current to the gate terminal of the first switching element, and the first transformer.
A third capacitor connected between the gate terminal and the emitter terminal of the first switching element,
With the 4th resistor connected in parallel to the 3rd capacitor,
A DC cutoff device characterized by being equipped with. A first mechanical circuit breaker connected between the positive electrode of the first DC system and the positive electrode of the second DC system,
A third diode having an anode terminal connected to a common connection point between the positive electrode of the first DC system and the first mechanical circuit breaker,
A first switching element in which a collector terminal is connected to the cathode terminal of the third diode, and
An LC circuit connected between the common connection point of the first mechanical circuit breaker and the positive electrode of the second DC system and the emitter terminal of the first switching element.
A third resistor connected between the emitter terminal of the first switching element and the negative electrode of the first and second DC systems, and
A first resistor having one end connected between the positive electrode of the second DC system and the first mechanical circuit breaker,
A first capacitor connected between the other end of the first resistor and the negative electrode of the first and second DC systems,
A second resistor and a second diode connected in series between the common connection point of the first resistor and the first capacitor, and the common connection point of the positive electrode of the first DC system and the first mechanical circuit breaker. ,
The fifth and sixth resistors connected in series between the common connection point of the first resistor and the first capacitor and the negative electrode of the first and second DC systems, and
The eighth resistor and the first switch connected in series between the common connection point between the positive electrode of the first DC system and the first mechanical circuit breaker and the common connection point of the fifth and sixth resistors,
A fourth capacitor connected between the common connection point of the fifth and sixth resistors and the negative electrode of the first and second DC systems, and
The 7th resistor and the 2nd coil connected in parallel to the 4th capacitor,
When the primary side detects the passing current of the second resistor, the secondary side outputs the current to the gate terminal of the first switching element, and the first transformer.
A third capacitor connected between the gate terminal and the emitter terminal of the first switching element,
With the 4th resistor connected in parallel to the 3rd capacitor,
With
The second coil is an operating coil of the first mechanical circuit breaker, and is a DC circuit breaker characterized in that the first mechanical circuit breaker is closed when a predetermined current flows through the second coil. The first mechanical circuit breaker and the second mechanical circuit breaker connected between the positive electrode of the first DC system and the positive electrode of the second DC system, and
An LC circuit and a third resistor sequentially connected in series between the first mechanical circuit breaker and the second mechanical circuit breaker and between the negative electrodes of the first and second DC systems.
A third diode having an anode terminal connected to a common connection point between the positive electrode of the first DC system and the first mechanical circuit breaker,
A first switching element in which a collector terminal is connected to the cathode terminal of the third diode and an emitter terminal is connected to a common connection point between the LC circuit and the third resistor.
A sixth diode having an anode terminal connected to a common connection point between the positive electrode of the second DC system and the second mechanical circuit breaker,
A second switching element in which a collector terminal is connected to the cathode terminal of the sixth diode and an emitter terminal is connected to a common connection point between the LC circuit and the third resistor.
A first resistor having one end connected to a common connection point between the positive electrode of the first DC system and the first mechanical circuit breaker.
A first capacitor connected between the other end of the first resistor and the negative electrode of the first and second DC systems,
A second switch and a second resistor connected in series between the common connection point of the first resistor and the first capacitor, and the common connection point of the positive electrode of the first DC system and the first mechanical circuit breaker. With the second diode
When the primary side detects the passing current of the second resistor, the secondary side outputs the current to the gate terminal of the first switching element, and the first transformer.
A third capacitor connected between the gate terminal and the emitter terminal of the first switching element,
With the 4th resistor connected in parallel to the 3rd capacitor,
A ninth resistor having one end connected to a common connection point between the positive electrode of the second DC system and the second mechanical circuit breaker.
A fifth capacitor connected between the other end of the ninth resistor and the negative electrode of the first and second DC systems,
The third switch and the tenth resistor connected in series between the common connection point of the ninth resistor and the fifth capacitor, and the common connection point of the positive electrode of the second DC system and the second mechanical circuit breaker, and With the 5th diode
When the primary side detects the passing current of the 10th resistor, the secondary side outputs a current to the gate terminal of the 2nd switching element, and a second current transformer.
A sixth capacitor connected between the gate terminal and the emitter terminal of the second switching element,
With the 11th resistor connected in parallel to the 6th capacitor,
With
When the current is flowing from the first DC system to the second DC system, the second switch is turned on and the third switch is turned off.
A DC cutoff device characterized in that when a current is flowing from the second DC system to the first DC system, the second switch is turned off and the third switch is turned on.

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