JP2017191764A - Silence arc current connection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switch which is connected and opened by a silence arc of a DC current system and a connection device.SOLUTION: In a DC switch circuit breaker and a connection device, a semiconductor switch having an insulation gate such as a MOSFET is connected through a mechanical contact S1 parallel with S3 as the mechanical contact of a main circuit. Further, in the semiconductor switch, a gate and a drain are connected at a high resistance R1, and are usually set to an ON state. When an electric current turns off the S3, the electric current is commutated to the semiconductor switch with a silence arc. After that, a gate voltage of the semiconductor switch is set to at a contact point S2, and a semiconductor electric current is cut-off. Thereafter, the semiconductor switch is completely released by opening S1 for safety.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a connection device such as a switch, a plug, and an outlet used in a DC power system.

    The present invention relates to a connecting device such as a DC current switch, plug and outlet, and belongs to a connecting / switching device required for a DC power system, solar power generation, electric railway, electric vehicle, indoor wiring, etc. The present invention relates to a direct current connection device composed of a semiconductor switch and a metal contact switch with low conduction loss so that it can be interrupted without generating an arc when it is energized.

    In recent years, with the advancement of semiconductor switches, high voltage and large current can be cut off at high speed with power MOSFETs and IGBTs with insulated gates, but semiconductor devices are still more resistant to electrical resistance than metal contacts. Is large, heat is generated, and some kind of cooling mechanism is required. On the other hand, when the direct current is interrupted by opening the metal contact, the current is not interrupted and arc discharge occurs and the current continues. The contact metal is melted and consumed by the high-temperature arc generated during the opening, and the current cannot be interrupted unless the arc is extinguished. In order to extinguish the arc, the arc length is increased by magnetism or the like to extinguish the arc, but the electrode is consumed and the life of the contact is shortened. Furthermore, there has been a problem that the DC connection device (connector), plug, and outlet cannot be stopped or disconnected while power is being supplied.

  In recent years, silicon carbide semiconductors have been put into practical use, and high-withstand-voltage semiconductor switches of several kV are being put into practical use in MOSFETs (Metal Oxide Field Effect Effect Transistors). Using this high withstand voltage semiconductor switch, it has become possible to provide an open / close switch for a high voltage DC power system, which has been difficult with metal contacts. However, the energization loss of the semiconductor switch is still larger than that of the metal contact, and the continuous energization requires a cooling device for the semiconductor switch, resulting in a large size. Therefore, by combining both advantages, there is a demand for an arc-free switch and a circuit breaker that are energized by a metal contact and energized and interrupted by a semiconductor switch only at the time of interruption.

  The present invention relates to an improvement in which the effect is further increased and the application range is expanded, except for the disadvantages of the arc-free switch formed by parallel connection of metal contacts and semiconductor switches described in Japanese Patent No. 5864006. Further, in the prior patent document 2, it is stated that “when a switch is configured for electric power use, a circuit that completely cuts off only with a metal contact may be required” and “a mechanical switch is inserted in series with the IGBT. It means that it is necessary. " The switch also needs to be added to the present invention. When it is S1, when conducting, S1 is turned on first, and when shut off, S1 is turned off last.

Patent 5864006 Japanese Patent Application No. 2011-53965 Japanese Patent Application No. 2016-13814

By the way, in the DC current interruption support circuit shown in FIG. 7 of the above-mentioned Patent Document 1, the semiconductor switch is always connected, and the parallel semiconductor circuits are always connected in parallel at the time of opening. In addition to the problem of reliability, there is a drawback that a slight current leaks through the gate circuit. Also, the main circuit current flows through the a contact of the metal contact, but it is used for the timing to turn off the semiconductor switch by using the time delay that the b contact turns on late, but the b contact uses a large current like the a contact. Without being handled, it is a weak current of several mA at several volts simply by short-circuiting the potential of the insulated gate. It is more reasonable to use a weak current switch with few incomplete contact problems and chattering problems.
In the double throw switch described in the prior art document 1, the time that flows in the semiconductor is the inversion time from the electrodes a to b, which is several ms, which is quite short and has a sufficient effect with the current carrying capacity of the semiconductor. Since the current capacity of the semiconductor in time is sufficient, it may not be as short as several tens of milliseconds, and the energizing contact and the gate control switch S2 need only be operated and interlocked between the switches S1 and S3. is there.

  The present invention has been made in view of the above points, and its purpose is not to require a gate drive power supply, a timer, etc., and with a simple circuit configuration, when interrupting a conducting current, it is bypassed with a semiconductor switch, It has a function to cut off the current by the semiconductor switch after being commutated to the semiconductor switch for a short time without generating the arc of the metal contact, and there is a mechanical contact S3 that bypasses when conducting, further preventing leakage current. Therefore, it is an object of the present invention to provide a connection device such as a switch, a plug, or a connector constituted by a mechanical contact S1 that completely disconnects the electrodes after the current is interrupted.

Means to solve the problem

In order to achieve the above object, according to the present invention, a procedure for connecting and releasing a load to a DC power supply will be described with reference to FIG.
To connect (1) When S1 is first turned on, the semiconductor circuit is connected. However, the gate of the semiconductor switch is connected to the S2b contact, the gate control voltage is zero, and the semiconductor switch remains off. .
(2) When the contact of S2 starts to operate, the gate voltage is increased by the resistance R1 of the semiconductor switch, and the semiconductor switch MOSFET becomes conductive at the self-bias voltage Vth (shreshhold voltage). The semiconductor device becomes conductive and current flows to the load.
(3) Finally, S3 is turned on. By short-circuiting between the power supply and the load at S3, which is a metal contact with low on-resistance, the current flows mainly through S3. Even if it flows slightly in the semiconductor, it generates little heat and the switch connection is completed. To do.

To release
(4) First, the connection device of S3 is released, but until the S2b contact is turned on, the semiconductor is in a conductive state by a self-gate trigger. Therefore, all current flows through the semiconductor and an arc is generated between the contacts. The voltage does not exceed about 10 V, and S3 is opened without arc.
(5) Next, when the S2b contact is turned on, the gate control voltage becomes zero, the semiconductor switch is turned off, and the current to the load is cut off. At this time, if an inductive load is cut off, a surge voltage is generated, so overvoltage protection is necessary.
(6) In order to remove a minute leakage current and to prevent an electric shock accident, S1 due to the mechanical metal contact is released without arc because the current is minute, and the complete opening operation is completed.
By opening and closing the switch and connecting / disconnecting the plug / connector through a series of operations of the three contacts S1, S2, and S3, it is possible to disconnect and release the connection without arc.

Effect of the invention

According to the above procedure, the metal contact can be conducted, disconnected and released without an arc.
That is, energization is performed by the operation of the S1 contact, and then the operation of the S2 contact, and then the contact S3 shorts this current and the semiconductor device current is commutated to the conducting contact of S3. Arcing, release is the opposite.

  As a result, AC contacts are fully open, that is, switches, outlets, plugs, etc. that have been insulated and turned off by an air layer are fully open according to the safety standards that have been used so far, even if they are direct current. It is thought that. In the release operation, the current flowing from the power source through the connecting device to the load side is commutated to the contact S1 because the semiconductor switch is turned on when the energizing contact S3 is opened, and the DC arc is turned on when the b contact of S2 is turned on. However, this can be done after the contact S3 has a sufficient opening distance. After being cut off by the semiconductor switch, the leakage current caused by the resistor R1 is cut off by opening the contact S1, but no arc is generated because the current is 1 mA or less. Eventually, the direct current is interrupted without generating any arc. (Claim 1) Even if the S2 contact is an a contact, it is possible if the semiconductor gate voltage can be controlled. The contact a needs to withstand the voltage of the main circuit, and since a high voltage may be applied to the semiconductor gate due to poor contact of the S1 contact, some kind of protection circuit is necessary. If the semiconductor is controlled using the b contact of S2, a high voltage is not generated here, so there is an advantage that a switch for weak current can be used. (Claim 1)

  For this reason, the electrode opening operation can be interrupted even if it takes time or even manually. Therefore, it is possible to connect the DC connection devices, plugs and outlets, etc. Can provide outlets. (Claims 2, 3, and 4)

  If the energization time of the semiconductor device becomes a problem when a large current is applied, the energization time can be reduced to a minimum of several ms if the inversion time of 2,3 mS is adopted for S2 of the arc-free double throw switch of the prior patent document 1. Can do.

  Here, if S1 is a mechanical contact having a DC blocking capability, for example, a DC circuit breaker with a blow-off effect by a magnetic field, various synergistic effects can be expected by series blocking with a semiconductor switch. One is that when the reliability of the mechanical contact is required, S1 may be considered as a safety switch, or as a backup when the semiconductor switch fails. Although the DC current interruption by the metal contact is a problem of electrode consumption due to the arc and the durability of the contact is significantly lower than that of the AC, the problem can be solved by series connection with the semiconductor switch. That is, a semiconductor switch is used to open and close the load current with a large number of switching times, and in the case of an accident current with a large current but a low frequency, S2 is not operated and is shut off at the mechanical contact S1. (Claim 5)

  Further, the method capable of interrupting without arc regardless of the direction of current even in direct current (Claims 6 and 7) is applicable to alternating current of high voltage and large current. AC current can be interrupted because it has a zero point, but when an arc is generated, electrode wear and noise problems occur. The use of the arc-free opening / closing of the present invention has an advantage that it can withstand frequent opening / closing and that noise caused by an arc does not occur at the time of interruption.

It is a circuit block diagram of Example 1 of this invention. FIG. 2 is a diagram for explaining a load current, a semiconductor current, and an ON / OFF sequence of each switch of S2, S1, and S3 when connected and released in the circuit configuration of FIG. It is a figure explaining the state of the switch by the block diagram of the DC plug of Example 1 of this invention, and insertion / extraction of a plug. It is a figure explaining the state of the switch by the block diagram of the connection apparatus to the direct current bus for large currents of Example 2 of the present invention, and plugging / unplugging. 1 is a circuit configuration diagram of a regenerative voltage adjusting circuit and a reverse current blocking type according to the present invention. FIG. 3 is a circuit configuration diagram for changing the current direction of the present invention or for alternating current. It is a circuit diagram when not using the diode bridge of the circuit for changing the current direction of the present invention or alternating current. It is a figure of structure and operation | movement description of the plug for DC of this invention, and an outlet socket. It is a circuit diagram of the arc-free switch by the double throw switch currently disclosed by patent document 1. FIG. For verification of the principle of the first embodiment, a DC high-voltage plug prototype photograph and a waveform of the voltage between electrodes at the time of interruption are shown.

  Hereinafter, embodiments of the present invention will be described based on Example 1 shown in FIGS. 1 to 3 and Examples shown in FIGS.

  First, FIG. 1 shows a circuit configuration of a DC power plug / outlet according to a first embodiment of the present invention. There are three switches and the connection sequence is S1 on → S2 on (b contact off) → S3 on. The sequence at the time of release is S3 off → S2 off (b contact on) → S1 off.

  FIG. 2 is a diagram showing the relationship between the switch and the current. FIG. 2 shows an outline of the sequence and current during the connection operation. At the time of connection, even if S1 is turned on by inserting an electrode, no current flows if the semiconductor switch is off. After the contact of S1 is turned on, the contact is further inserted, the contact b of S2 is opened by pressure, the contact b is opened, the gate voltage becomes Vth (Shreshold voltage), and the semiconductor switch is turned on. Finally, S3 connected to the DC power supply is turned on, and most of the semiconductor current flows through S3 having a small resistance. The plug turns on S1, then turns off S2b, and finally turns on S3.

  FIG. 2 shows an outline of the sequence and current during the release operation. In the connected state, S1 and S3 are in the ON state, S2 is in the OFF state, and the load current flows mainly in S3. When the plug is pulled out for release, S3 is opened first, but S1 is opened without arc because the semiconductor switch is ON. Subsequently, when the plug is pulled out and S2b, which has become free, turns on the b contact, the gate voltage becomes zero, the semiconductor switch is turned off, and the load current is interrupted without arcing. Finally, the current of 1 mA or less flowing through R1 remaining due to the opening of S1 is interrupted to completely release the current.

FIG. 3 is a configuration diagram of a coaxial DC plug which is one embodiment of the circuit configuration of FIG. 1 and an operation explanatory diagram in which the switches S1, S2 and S3 are made into a coaxial plug and a receptacle on the receiving side by plugging / unplugging. Show. The plug in FIG. 3 is a plug and a jack for connecting the power source and the load, and the current return is connected separately. (Claim 2)
(1) State before connection (2) Insertion of the plug starts and the DC plug S1 becomes conductive, but no current flows because the gate voltage is short-circuited.
(3) When the insertion proceeds, S2b is turned off and the MOSFET becomes conductive.
(4) Further plugs are inserted and S3 is turned on to complete conduction.
(5) Start of blocking. Conducted at S3.
(6) Even if S3 is turned off, since the current is conducted by the MOSFET, it commutates without arc.
(7) When S2b is turned on, the gate voltage becomes zero and the current is cut off by the MOSFET.
(8) S1 also leaves and completes the shut-off operation.
(9) The plug release is complete.

  FIG. 10 demonstrates that the DC plug described in FIG. The waveform of the DC plug and jack appearance and the re-emergence voltage between the electrodes is shown. The re-emergence voltage is about 180 V at maximum, and it can be seen from this waveform that no arc has occurred. This is because when an arc is generated, an irregular voltage due to plasma fluctuation is seen in the voltage waveform as shown in the figure.

FIG. 4 is a structural diagram of a DC large current connection device according to Embodiment 3 of the present invention. (Claim 3)
In Example 3, S1 is the central conductor of the movable contact that contacts the DC bus. S3 is an outer conductive conductor of the movable contact that contacts the DC bus in a wide area. The center conductor is always pushed from below by a spring and protrudes from the conductive conductor, so that S1 first contacts the bus. It is arranged so that S2 is turned off by the operation when the central conductor is pressed in contact with the bus bar. The central conductor is directly connected to the drain of the MOSFET, and the external conductive conductor is directly connected to the load. S2b is connected to the gate and the source of the MOSFET to be a normally closed contact. With this structure, S1 is turned on, then S2 is turned off, and finally S3 comes into contact to complete the connection with the bus, and the release is reversed.

  In FIG. 5, a C-R2 circuit using a Miller integration effect for reducing the noise by controlling the rate of increase of the regenerative voltage is added. Furthermore, an application example is shown in which a diode for preventing reverse current conduction by the body diode of the MOSFET is inserted in the drain of the MOSFET. Furthermore, a protection diode is added between the source and gate to protect the gate reverse voltage. If this is a constant voltage diode of about 15 V, it is further effective for protecting forward voltage. Further, when S2 is a double throw switch or a micro switch, since there is an a contact of S2, if it is used in series with S1, the energization time of the semiconductor device becomes only the inversion time of the double throw switch, so that the energization of the semiconductor There is an effect of increasing the capacity.

FIG. 6 shows a circuit configuration in which the circuit configuration of the first embodiment can be applied to both direct current and alternating current. A diode bridge is connected between S1 and S3 to make a direct current, and the MOSFET is used as a semiconductor switch to make current bidirectional. The gate is equipped with a Miller integral effect CR and a protection diode. In this case, S2 needs to be insulated from the S1 and S2 circuits. This S2b contact can be a weak voltage switch.

  FIG. 7 shows a modification for the alternating current of FIG. 6 or the direct current whose current direction changes. The MOSFET becomes a current bidirectional switch in reverse series. There are fewer parts than FIG.

  FIG. 8 shows an embodiment of a DC plug and an outlet. In S1 and S3, the metal contacts are sequentially contacted according to the insertion. S2b is placed at the inserted intermediate position. When S1 is turned on, the b contact is turned off, the b contact is turned off, the semiconductor device is turned on, and a current flows, and then S3 is turned on. Bypassing the semiconductor circuit. On the contrary, when S3 is turned off and S2b is turned on, the current is cut off by the semiconductor device, and finally S1 is released to complete the opening. This circuit diagram is dedicated to one direction of direct current with the simplest configuration, but it is also possible to control the regenerative voltage by making the semiconductor circuit as shown in FIG. 5, and it can also be applied to alternating current using FIG. 6 or FIG. Is possible.

(Other embodiments)
(1) Although the MOSFET is used as the semiconductor device in the above embodiment, a voltage control device having an insulated gate such as an IGBT (insulated gate bipolar transistor) may be used.
(2) In the above embodiment, the case where the present invention is applied to the connection device has been described. However, since S1, S2, and S3 need only be turned on and off in order, a manual rotary switch, a slide switch, It can be applied not only to AC circuit breakers and magnetic contactors. If there is no arc even if the opening speed is slow, there is no problem with the service life, so a metal contact with low contact resistance can be selected, and the drive mechanism changes greatly.
(3) If the arc-free connection mechanism of the present invention is adopted for an AC high-speed arc breaker for AC distribution and a switch, it has been conventionally opened to minimize the arc time or rapidly increase the arc voltage. Although a mechanism to increase the speed of the machine was necessary, this is no longer necessary, and quietness, long life, and miniaturization are possible.
(4) In an on-load tap switching device in an AC power transmission system, if the contact can be switched on and off without arcing, tap switching can be expected to be faster, more frequent, and longer.

By utilizing the fact that the on-resistance of the mechanical contact is small and that the semiconductor switch can be interrupted without arcing, it becomes possible to easily remove the direct current that has been difficult to connect and release. Further, even if an alternating current is interrupted without arcing at a mechanical contact, the life of the contact can be extended and the reliability can be improved.

1: DC power supply 2: Load 3: Q1 insulated gate semiconductor switch 4: High resistance R1
5: Switch (S1: Start contact, S2: Gate control SW, S3: Energized contact)
6: Arc-free opening / closing and connection device

Claims (7)

  In a DC power system switching / connecting device, when a mechanical metal contact S3 is opened, a circuit comprising a semiconductor switch having an insulated gate such as a MOSFET is connected in parallel so that no arc is generated at the contact. Since the gate and drain of the semiconductor switch are connected with high resistance R1 so that the arc is not generated, the current of S3 is commutated to the semiconductor switch without arc. After that, when the contact S2b is turned on, the gate voltage of the semiconductor switch is lowered, the semiconductor switch is turned off to cut off the current, and thereafter, S1 is also opened. Connected device.   Using the connection circuit according to claim 1, the center conductor of the DC plug is set to S1, the contact that is opened when the insertion of the plug is detected is set to S2b, and the conductor that the outer conductor of the plug finally contacts is S3. DC plugs and jacks that can be plugged in and out without arc.   The contact that is crimped and connected to the bus bar electrode using the connection circuit according to claim 1 has S1 as a central conductor of the movable contact that contacts the DC bus, and S3 is a movable that contacts the DC bus in a wide area. As the outer conductive conductor of the contact, the center conductor is always pushed from below by a spring and protrudes from the conductive outer conductor. When the center conductor is first pressed against the bus, the S1 is in contact with the bus. The S2 switch is arranged so that S2b is turned on and off by the operation, the central conductor is directly connected to the drain of the MOSFET, the external conductive conductor is directly connected to the load, and S2b is connected to the gate and the source of the MOSFET, respectively. Due to the closed contact structure, it is turned on from S1, then S2b is turned off, and finally S3 comes into contact to complete the connection with the busbar, and the release is the reverse Unconnected to direct current connection device without arc is to be.   In a plug and outlet for DC, the plug has a positive electrode, a negative electrode, and an insulating rod serving as a third electrode. Inside the outlet is a contact that contacts the positive electrode of the main circuit simultaneously with insertion. A circuit according to claim 1, further comprising: a contact element of S1 and S3 that comes into contact with each other as it is inserted into the electrode, and further has a mechanism for turning the S2b contact on and off in the middle of insertion by using the insulating rod as the third electrode of the plug. A DC power outlet that connects components and releases them without arcing.   2. The switching / connecting device according to claim 1, wherein a series of a capacitor C and a resistor R2 is connected between the mechanical contact S1 and the b contact of S2, and the midpoint thereof is connected to the gate of the semiconductor switch so that the regenerative voltage is reduced. A circuit that controls the rise by Miller integration circuit is added, and furthermore, a diode is connected to the drain of the semiconductor switch to prevent reverse current blocking, and a varistor is installed for overvoltage protection of the semiconductor switch. Append.   5. The connection device according to claim 1, wherein a gate of a semiconductor switch having an insulated gate which is connected to a diode bridge between the mechanical contacts S1 and S3 so that a current can flow regardless of a power direction is controlled by the S2b contact. Thus, the configuration of the arc-free interrupting circuit which can commutate and interrupt the current of S3 regardless of the current direction.   5. The connection device according to claim 1, wherein two MOSFETs are connected in reverse series between the mechanical contacts S1 and S3, their gates are connected to their respective drains with a high resistance R1, and both gate voltages are controlled. A configuration of an arc-free interruption circuit that is connected to the S2b contact so that the current of S3 can be commutated and interrupted regardless of the current direction.

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