JP6399848B2 - Switch - Google Patents

Description

  The present invention relates to a switch having a bidirectional current interruption function applied to a DC power distribution circuit and the like.

    In recent years, with the widespread use of photovoltaic power generation systems, power supply systems using storage batteries, etc., research and development of DC switches applied to the power distribution circuits of these systems is progressing.

  By the way, a conventional DC switch (a mechanical switch (reed switch) such as a circuit breaker (MCCB), an earth leakage circuit breaker (ELB), an electromagnetic switch (MAG), etc.) is provided with a switching operation. Due to the influence of the DC arc generated between the contacts, there is a problem that the contacts are damaged and consumed at an early stage, causing malfunction of the switch.

  For this purpose, various arc extinguishing countermeasures have been proposed in the past. As an example, a solid state switch such as an IGBT (Insulated Gate Bipolar Transistor), a MOS-FET, or a GTO thyristor is used as a circuit contact of a mechanical switch. ) In parallel, the main circuit current that was flowing to the circuit contact of the mechanical switch when the mechanical switch was opened is commutated to the semiconductor switch, and the arc generated between the circuit contacts of the mechanical switch is immediately generated. There is known a DC switch in which the circuit current is interrupted by turning off the semiconductor switch after that and the circuit current is cut off (see, for example, Patent Document 1).

  However, the switch disclosed in Patent Document 1 requires a drive power supply independent of the gate drive circuit of the semiconductor switch and its control. Therefore, the inventors omit the independent drive power supply of the gate drive circuit, and instead apply the arc voltage generated between the circuit contacts during the opening operation of the mechanical switch to the gate of the semiconductor switch (IGBT). Therefore, a switch has been proposed previously (see Patent Document 2) in which the semiconductor switch is controlled to be turned on and off in synchronization with the opening operation of the mechanical switch (see Patent Document 2). The details of the operation from opening to current interruption are described in detail.

  In the switch disclosed in Patent Document 2, the IGBT of the semiconductor switch is controlled to be turned on and off using the arc voltage between the circuit contacts generated during the opening operation of the mechanical switch, and the main circuit current is controlled from the mechanical switch. The semiconductor switch is commutated to be cut off, which eliminates the need for an independent gate drive power supply like the switch disclosed in Patent Document 1 described above, thereby simplifying the control of the semiconductor switch.

  By the way, a circuit in which the circuit current is reversed in the forward and reverse directions by charging and discharging the storage battery, such as a power supply device equipped with a storage battery, or a direct current that performs reverse power flow between distributed DC power sources such as a photovoltaic power generation system For a DC switch applied to a system linkage circuit or the like, a bidirectional current cut-off function is required for a semiconductor switch connected in parallel to a circuit contact of the mechanical switch. In the DC switch, the IGBT of the semiconductor switch is a unidirectional element, so if the energization direction of the main circuit current is reversed in the forward and reverse directions, the circuit current cannot be commutated from the mechanical switch to the semiconductor switch. .

  Therefore, the inventors have established a mechanical switch as a semiconductor switch connected in parallel to the circuit contact of the mechanical switch by combining two IGBTs connected in reverse series and a diode connected in reverse parallel to each IGBT. The main circuit current is energized by controlling ON / OFF of the IGBT of the bidirectional switch by using the arc voltage between the circuit contacts generated during the opening operation of the mechanical switch after being connected in parallel to the circuit contact of the switch. Japanese Patent Application No. 2013-89453 (2013) has devised a DC switch having a bidirectional cutoff function that allows a circuit current to be commutated from a mechanical switch to a semiconductor switch even when the direction is forward and reverse. (Applied on April 22), the circuit configuration and the main circuit current cutoff operation will be described below with reference to FIGS. That.

  That is, in FIG. 10, the circuit contact (for one pole) of the mechanical switch 2 connected to the DC main circuit 1 is composed of a pair of fixed contacts 2a and 2b and a bridge movable contact 2c. A bidirectional semiconductor switch 3 having the following configuration is connected to the contact in parallel. Here, the semiconductor switch 3 is connected in reverse parallel to two IGBTs 4 (hereinafter referred to as IGBT-1 and IGBT-2) connected in reverse series as shown in the figure, and to each of the IGBT-1 and IGBT-2. The diodes D-1 and D-2 constitute a bidirectional switch. Reference numerals 11 and 12 are main circuit terminals.

  For the gates of the IGBT-1 and IGBT-2, voltage dividing resistors 5, 6-1, 6-2, overvoltage suppressing elements 7-1, 7-2 such as varistors and Zener diodes, A gate drive circuit configured by combining capacitors 8-1 and 8-2 as shown in the figure is connected between the gate terminal and emitter terminal of each IGBT and the bridging movable contact 2c of the mechanical switch 2, and the mechanical switch The arc voltage generated between the fixed / movable contacts during the opening operation is applied to the gate terminals of the IGBT-1 and IGBT-2 for turn-on and turn-off control.

  With the above circuit configuration, in the energized state where the circuit contact of the mechanical switch 2 is closed, the main circuit current of the DC main circuit 1 is the main circuit as shown by the solid arrows in FIGS. 11 (a) and 11 (b). It flows through the circuit contact of the mechanical switch 2 corresponding to the polarity of the terminals 11 and 12. In this energized state, the circuit contact of the mechanical switch 2 is closed, the potential difference between the contacts is 0V, and both the IGBT-1 and IGBT-2 of the semiconductor switch 3 are in the OFF state.

  When the mechanical switch 2 is opened from this energized state, an arc arc is generated between the fixed contacts 2a, 2b and the bridge movable contact 2c as shown in FIGS. 12 (a) and 12 (b). Due to (voltage drop), a control current as shown by a dotted arrow in FIG. 12 flows through the gate drive circuit of the semiconductor switch 3. As a result, similar to the operation described in the switch of Patent Document 2 above, the capacitor 8- connected to the gates of IGBT-1 and IGBT-2 corresponding to the flow direction of the main circuit current (solid arrow). 1 and 8-2 are charged in the forward direction via the voltage dividing resistor 5. When the charging voltage of the capacitors 8-1 and 8-2 rises and the voltage (forward bias voltage) applied to the gate of the IGBT exceeds a predetermined threshold value (gate-emitter threshold voltage), the IGBT− 1 or IGBT-2 is turned on and turned on.

  In the state in which an arc voltage is generated between the circuit contacts in accordance with the opening operation of the mechanical switch 2, although not shown, the capacitor 8-2 in FIG. 12A and the capacitor 8- in FIG. 1 is charged by receiving the arc voltage between the contacts of the mechanical switch 2, but the charging potential of the capacitor corresponding to the IGBT-2 in FIG. 12A and the gate of the IGBT-1 in FIG. Therefore, this IGBT remains in the OFF state.

  As a result, the main circuit current that has been flowing through the circuit contact of the mechanical switch 2 until now is commutated to the circuit of the semiconductor switch (bidirectional switch) 3 as shown by the solid arrows in FIGS. 13 (a) and 13 (b). To do. In this case, in FIG. 13A, the main circuit current flows through the diode D-2 and IGBT-1 (ON state), and in FIG. Conversely flows through the diode D-1 and IGBT-2 (ON state), and the arc generated between the circuit contacts with the opening operation of the mechanical switch 2 until now is immediately extinguished. Become.

  Then, when the arc generated between the contacts of the mechanical switch 2 disappears, the current that has been flowing to the gate drive circuits of the IGBT-1 and IGBT-2 through the bridge movable contact 2c until then disappears. The charged charges stored in −1 and 8-2 are discharged through the voltage dividing resistors 6-1 and 6-2 as indicated by dotted arrows in the drawing. Then, when the discharge of the capacitors 8-1 and 8-2 progresses and the gate voltages of the IGBT-1 and IGBT-2 decrease below a predetermined threshold value, the IGBT is turned off and turned off, and as shown in FIG. The circuit current flowing in the DC main circuit 1 is completely cut off.

  As can be seen from the above description, two IGBT-1 and IGBT-2 in which the semiconductor switch 3 connected in parallel to the circuit contact of the mechanical switch 2 is connected in reverse series, and reversely parallel to the IGBT-1 and IGBT-2. By forming a bidirectional switch with the connected diodes D-1 and D-2, the bidirectional circuit current is transferred from the mechanical switch 2 to the semiconductor switch 3 without being restricted by the energization direction of the DC circuit 1. It can be blocked by flowing.

Japanese Patent Laid-Open No. 8-106839 JP 2013-41882 A

  In the conventional switch described in FIGS. 10 to 14 described above, the conventional IGBT is used as the switching element (IGBT-1, IGBT-2) of the semiconductor switch 3 connected in parallel to the circuit contact of the mechanical switch 2. Is used.

  By the way, since the conventional IGBT does not have a withstand voltage (reverse withstand voltage) with respect to the reverse applied voltage, in the switch of the conventional proposal (see FIG. 10) described above, each of the IGBT-1 and IGBT-2 connected in reverse series is provided. The diodes D-1 and D-2 are connected in reverse parallel to bear the reverse blocking voltage of the bidirectional switch.

  For this reason, in the energized state in which the main circuit current is commutated to the semiconductor switch 3 with the opening operation of the mechanical switch 2 (see FIGS. 13A and 13B), the circuit current is equal to that of the IGBT and the diode. As a result, a voltage drop corresponding to (ON voltage of the IGBT) + (forward voltage of the diode) is generated in the circuit of the semiconductor switch 3, and this voltage is the IGBT or a single diode. It is twice as much as the element. For this reason, in a state where the main circuit current is commutated from the mechanical switch 2 to the circuit of the semiconductor switch 3, the conduction loss generated in each element of the IGBT and the diode is added and the power loss of the semiconductor switch 3 increases.

  In addition, the switching loss when the circuit current is commutated from the mechanical switch 2 to the semiconductor switch 3 is also added to the switching loss between the IGBT and the diode, so that the circuit current is transferred from the mechanical switch 2 to the semiconductor switch 3. The switching time to flow becomes longer, and the longer the switching time, the longer the time until the arc generated between the circuit contacts of the mechanical switch 2 disappears. It will be shortened. For example, the product specifications of electromagnetic switches applied to mechanical switches usually require guaranteeing switching operations of several hundred thousand times or more. However, if the circuit contact life is shortened, the required number of switching times is guaranteed. Difficult to do.

  In addition, as the loss of the semiconductor switch 3 increases, the heat load for cooling the semiconductor element also increases, so that the cooling section becomes larger and the weight and cost also increase.

  The present invention has been made in view of the above points, and a bidirectional semiconductor switch is connected in parallel to a mechanical switch as in the above-described conventional proposal, and is generated between circuit contacts when the mechanical switch is opened. A semiconductor that commutates the circuit current when the mechanical switch is open for a switch with a bidirectional current interrupt function that controls the semiconductor switch ON / OFF using the arc voltage as the gate control signal. Reduces and shortens switch conduction loss and switching time to further extend the life of contact points of mechanical switches. At the same time, it reduces the number of elements of semiconductor switches to reduce size, weight, and cost. An object of the present invention is to provide an improved switch which can be improved.

In order to achieve the above object, according to the present invention, a switch is applied to a circuit in which a current direction is reversed in both forward and reverse directions, and a bidirectional semiconductor switch is connected in parallel to a circuit contact of a mechanical switch connected to the circuit. When the mechanical switch is opened, the circuit current is commutated to the semiconductor switch to extinguish the arc generated between the contacts of the mechanical switch, and then the semiconductor switch is turned off to cut off the current. In the switch
As the semiconductor switch, a bidirectional switch formed by reverse-parallel connection of two reverse blocking IGBTs (RB-IGBT: Reverse Blocking Insulated Gate Bipolar Transistors) having reverse breakdown voltage performance is connected in parallel to the mechanical switch. Above, when opening the mechanical switch, the arc voltage generated between the circuit contacts is applied to the gate of the reverse blocking IGBT to commutate the main circuit current to the semiconductor switch, and then the semiconductor switch is turned off. The circuit current is controlled to be cut off , and a three-pole type switch having three sets of circuit contacts is used as the mechanical switch, and the bidirectional switch is connected in parallel to the circuit contact with one pole as a main contact. The remaining two pole circuit contacts are inserted and connected to the forward and return paths of the main circuit as disconnecting contacts .

  According to the switch configured as described above, the following effects can be obtained.

  First, as a semiconductor switch connected in parallel to the circuit contact of the mechanical switch, a bidirectional switch in which two reverse blocking IGBTs are connected in reverse parallel is used, and the opening of the mechanical switch is further opened with respect to this bidirectional switch. The arc voltage generated between the circuit contacts during operation is added to the gate of the reverse blocking IGBT to control ON / OFF, so that the opening operation of the mechanical switch can be performed without requiring an independent gate drive power supply. In synchronism with this, it is possible to provide a bidirectional cutoff function in which the main circuit current is commutated to and cut off from the semiconductor switch.

  Further, compared with a conventional bidirectional switch (see FIG. 10) configured by combining a conventional IGBT with a diode, contact wear due to an arc generated by the mechanical switch can be reduced, and the life of the switch can be extended.

  Further, by omitting the diode connected to the conventional IGBT, the number of elements constituting the bidirectional semiconductor switch is reduced, and the semiconductor switch mounted on the switch can be reduced in size, weight, and cost. .

  As an embodiment of the present invention, a three-pole switch is used as the mechanical switch, the one-pole contact is used as a main contact, the bidirectional switch is connected in parallel to the circuit contact, and the remaining two-pole contact Is used as an auxiliary contact for disconnection in the forward and return paths of the main circuit, so that the load can be completely disconnected from the power supply by opening the mechanical switch so that load maintenance and inspection can be performed safely without fear of electric shock. In addition, the semiconductor switch connected in parallel with the mechanical switch can be completely disconnected from the power source in the same manner, and unnecessary malfunction can be prevented.

It is a schematic circuit diagram of the switch concerning Example 1 of the present invention. It is a figure showing the energization path | route of the main circuit current at the time of closing of the mechanical switch of FIG. 1, Comprising: (a), (b) is a figure corresponding to the forward and reverse direction of a circuit current, respectively. It is a figure showing the energization state immediately after opening a mechanical switch from the state of FIG. 2, Comprising: (a), (b) is a figure corresponding to the forward and reverse direction of a circuit current, respectively. FIG. 4 is a diagram illustrating an energization path in a state where a circuit current is commutated from the state of FIG. 3 to a bidirectional switch, and (a) and (b) are diagrams corresponding to forward and reverse directions of the electric circuit current, respectively. FIG. 5 is a diagram illustrating a state in which the semiconductor switch is turned off from the states of FIGS. 4A and 4B to cut off the circuit current. It is a schematic circuit diagram of the switch corresponding to Example 2 of the present invention. It is a schematic circuit diagram of the switch corresponding to Example 3 of the present invention. FIG. 8 is a structural diagram of a three-pole electromagnetic switch used in the mechanical switch of FIG. 7, wherein (a) is a longitudinal sectional view showing the internal mechanism, and (b) is a plan view of (a). It is a schematic circuit diagram of the switch corresponding to Example 4 of the present invention. A bidirectional switch that combines a diode with a conventional IGBT is connected in parallel to the circuit contact of the mechanical switch, and the semiconductor switch is turned ON / OFF using the arc voltage generated between the circuit contacts when the mechanical switch is opened. It is a schematic circuit diagram showing the conventional DC switch to be controlled. It is a figure showing the energization path | route of the main circuit current at the time of closing of the mechanical switch of FIG. 10, Comprising: (a), (b) is a figure corresponding to the order and reverse direction of a circuit current, respectively. FIG. 12 is a diagram illustrating an energized state immediately after opening the mechanical switch from the state of FIG. 11, and (a) and (b) are diagrams corresponding to the forward and reverse directions of the circuit current, respectively. It is a figure showing the energization path | route in the state where the circuit current commutated from the state of FIG. 12 to the bidirectional | two-way switch, Comprising: (a), (b) is a figure corresponding to the order of a circuit current, and a reverse direction, respectively. It is a figure showing the state which cut off the circuit current by carrying out OFF control of the semiconductor switch from the state of Fig.13 (a), (b).

  Hereinafter, the configuration of the switch and the current interruption operation according to the present invention will be described based on the illustrated embodiments. In the drawings of the respective embodiments, the same reference numerals are given to circuit components corresponding to FIGS.

First, a circuit configuration of a switch according to the present invention and a current interruption operation thereof will be described with reference to FIGS.

  That is, the switch 3 in the illustrated embodiment is similar to the previously proposed switch (see FIG. 10) described above, and is a mechanical switch 2 (wiring circuit breaker, earth leakage circuit breaker) connected to the main circuit 1 of the DC system. , Electromagnetic switch, etc.) and a bidirectional semiconductor switch 3 connected in parallel to the circuit contact 21 of the mechanical switch 2. The mechanical switch 2 includes fixed contacts 2a and 2b and a bridge movable contact 2c.

  Here, the semiconductor switch 3 shown in the figure is configured by connecting two reverse blocking IGBTs (Reverse Blocking Insulated Gate Bipolar Transistors) 4-1 and 4-2 having reverse breakdown voltage performance in reverse parallel connection. The bidirectional switch is connected in parallel to the mechanical switch 2, and the diode D1 and D2 shown in FIG.

  In FIG. 1, voltage dividing resistors 5-1, 5-2, 6-1, 6-2, varistors, Zener diodes, etc. are used as gate drive circuits for the reverse blocking IGBTs 4-1, 4-2. The overvoltage suppression elements 7-1 and 7-2 and the capacitors 8-1 and 8-2 are connected as shown in the figure, and the bridge movable contact 2c of the circuit contact 21 of the mechanical switch 2 and both terminals of the main circuit 1 are connected. 11 and 12 is formed, and capacitors 8-1 and 8-2 of the gate drive circuit 9 are connected in parallel between the gates / emitters of the reverse blocking IGBTs 4-1 and 4-2, respectively. It is connected.

  Next, the circuit current cutoff operation by the switch of FIG. 1 will be described. First, FIGS. 2A and 2B show an energized state in which the current of the DC main circuit 1 flows in the forward direction and the reverse direction. In this energized state, the circuit current flows through the circuit contact 21 of the mechanical switch 2 that is closed, and the reverse blocking IGBTs 4-1 and 4-2 of the semiconductor switch 3 are both in the OFF state. Then, there is no conduction loss or heat generation in the semiconductor switch 3. This energization state is the same as that of the conventional proposal shown in FIG.

  Then, when a mechanical switch 2 is opened by giving a contact opening command to the switch 3 from the energized state of FIGS. 2 (a) and 2 (b), the mechanical type as shown in FIGS. 3 (a) and 3 (b). Immediately after the switch 2 is opened, an arc arc is generated at the circuit contact 21, and a control current represented by the dotted arrow shown in the figure flows through the gate drive circuit 9 due to the arc voltage (voltage drop).

  As a result, in the same manner as the control operation described in the conventionally proposed switch (see FIGS. 12A and 12B), the reverse blocking IGBT 4-1 corresponds to the flow direction of the main circuit current (solid arrow). , 4-2 are connected to the gate terminals of capacitors 8-1 and 8-2 in the forward direction through voltage dividing resistors 5-1 and 5-2. At this time, the voltage dividing resistors 5-1 and 5-2 function as limiting resistors for charging current. When the charging voltage of the capacitors 8-1 and 8-2 rises and the voltage applied to the gate of the IGBT (gate forward bias voltage) exceeds a predetermined threshold (gate-emitter threshold voltage), the reverse occurs. The blocking IGBT 4-1 or 4-2 is turned on, and the circuit current of the main circuit 1 starts to commutate from the mechanical switch 2 to the bidirectional semiconductor switch 3. 4A and 4B show a state where the circuit current is commutated to the semiconductor switch 3. FIG.

  The capacitors 8-1 and 8-2 may use the parasitic capacitance between the gates and emitters of the reverse blocking IGBTs 4-1 and 4-2. In this case, the capacitors 8-1 and 8-1 shown in FIG. 8-2 can be omitted.

      When the commutation of the circuit current is completed, the arc generated between the circuit contacts in accordance with the opening operation of the mechanical switch 2 is immediately performed as described in the conventional switch operation (see FIG. 13). The control current that has flowed to the gate drive circuit 9 through the bridge movable contact 2c until now disappears. In this state, the voltage applied to the voltage dividing circuit of the gate drive circuit 9 is only the ON voltage (about 4V) of the bidirectional semiconductor switch 3, and is stored in the Image capacitors 8-1 and 8-2. The charged charge is discharged through the voltage dividing resistors 6-1 and 6-2 as indicated by the dotted arrows shown in the figure. When the discharge of the capacitors 8-1 and 8-2 progresses and the gate voltage of the reverse blocking IGBTs 4-1 and 4-2 falls below a predetermined threshold value, the reverse blocking IGBT is turned off and turned off. As a result, as shown in FIG. 5, the main circuit current flowing in the DC main circuit 1 is completely cut off.

  The discharge timing of the capacitors 8-1 and 8-2 is determined by the time constant of the discharge circuit of the capacitors 8-1 and 8-2 and the voltage dividing resistors 6-1 and 6-2, and this time constant is adjusted. As a result, after the arc generated between the circuit contacts of the mechanical switch 2 disappears, the current commutated to the semiconductor switch 3 is cut off by the OFF control of the reverse blocking IGBTs 4-1 and 4-2. It is possible to adjust the time. Also, since this time constant determines the turn-off time of the reverse blocking IGBT, the current decay time (di / dt) in the reverse blocking IGBT is controlled by selecting an appropriate time constant in the order of ms, for example. Thus, it is possible to effectively suppress the surge voltage generated immediately after the circuit current is cut off.

  Next, FIG. 6 shows a schematic circuit of an application embodiment in which a part of the gate drive circuit 9 in the first embodiment is changed. In the second embodiment, the voltage dividing resistor 5 is connected to the bridging movable contact 2c of the mechanical switch 2 in place of the voltage dividing resistors 5-1 and 5-2 in the gate drive circuit 9 of FIG. The voltage dividing resistors 6-1 and 6-2 are T-connected to the resistor 5 to form a voltage dividing circuit of the gate drive circuit. The gate drive circuit 9 is also a mechanical switch as in the first embodiment. The circuit current can be commutated from the mechanical switch 2 to the semiconductor switch 3 in synchronism with the opening operation of 2 and cut off.

Next, Embodiment 3 according to the present invention will be described with reference to FIGS. In the switch according to the third embodiment, the load connected to the power supply through the switch is completely disconnected from the power supply by opening the mechanical switch, and there is no risk of electric shock in maintenance and inspection of the load. FIG. 7 shows the schematic circuit of the switch, and FIG. 8 shows the structure of this mechanical switch.

  That is, as shown in the schematic circuit diagram of FIG. 7, the mechanical switch 2 connected to the power distribution main circuit 1 connecting the power source 10 and the load 20 is linked to the opening / closing operation of the mechanical switch 2. Thus, a three-pole type switch (for example, an electromagnetic contactor) having three sets of circuit contacts 21-1, 21-2, and 21-3 that perform switching operation is used. Here, one of the three sets of circuit contacts, for example, the center contact circuit contact 21-2 is used as a main contact, and the semiconductor switch 3 (reverse blocking IGBTs 4-1 and 4-2 is connected to the circuit contact 21-2. Bidirectional semiconductor switches connected in reverse parallel) are connected in parallel, and the remaining two-pole circuit contacts 21-1 and 21-3 are connected to the forward and return paths of the main circuit 1 as disconnecting contacts. Yes.

  The terminals 25a to 25f shown in the figure are external terminals (screw terminals) corresponding to the above-mentioned three-pole circuit contacts 21-1, 21-2 and 21-3, and the power supply 10 is connected to the external terminals 25a and 25e. In the meantime, the load 20 is connected between the external terminals 25d and 25f, and the external terminals 25b and 25c are connected by another lead wiring 13.

  FIGS. 8A and 8B are structural diagrams of a three-pole electromagnetic switch in which the mechanical switch 2 and the semiconductor switch 3 of FIG. 7 are combined. In the figure, reference numeral 22 denotes a frame (case) of the electromagnetic switch. ) 23 is an electromagnet for opening / closing operation built in the frame 22, 24 is a movable contact holder connected to the movable iron core of the electromagnet 23, and 21a and 21b are circuit contacts (double contact type contacts) 21-1 for each pole in FIG. , 21-2, 21-3, 21c, 21c are bridged movable contacts mounted on the movable contact holder 24 and opposed to the fixed contacts 21a, 21b. The package of the semiconductor switch 3 is mounted on the top of the frame of the electromagnetic contactor, and is connected in parallel between the external terminals 25c and 25d of the electromagnetic switch via lead wires.

  According to the above configuration, when the mechanical switch (three-pole electromagnetic switch) 2 connected to the main circuit between the power source 10 and the load 20 is opened, the power source 10 and the load 20 are completely disconnected. In addition, the load 20 can be safely inspected without fear of electric shock. Further, the semiconductor switch 3 connected to the mechanical switch 2 is also disconnected from the power source in the same manner as described above when the electromagnetic switch is opened, so that unnecessary malfunction of the semiconductor switch 3 can be prevented.

  The circuit current commutated from the mechanical switch 2 to the semiconductor switch 3 when the circuit current is cut off is cut off by controlling the reverse blocking IGBTs 4-1 and 4-2 of the semiconductor switch 3 to be turned off. As a switching characteristic, there is some delay due to tail current at turn-off. For this reason, if the circuit contacts 41-1 and 41-3 (contacts for disconnection) in FIGS. 7 and 8 are opened before the interruption of the current commutated to the semiconductor switch 3 is completed, an arc is generated at the circuit contacts. May occur.

  Therefore, in order to prevent arcing of the disconnecting contact, for example, between the circuit contact 21-2 (main contact) and the circuit contacts 21-1, 21-3 (disconnecting contact) in the electromagnetic switch of FIG. Different contact wipe amounts may be set so that the disconnecting contact is opened slightly later than the main contact when the electromagnetic switch is opened.

  Next, as an application example of the present invention, a schematic circuit of a switch according to Example 4 is shown in FIG.

  In the switch according to the first embodiment shown in FIG. 1, the circuit contact 21 of the mechanical switch 2 is composed of fixed contacts 2a and 2b and a bridge movable contact 2c, and the gate movable circuit 9 is connected to the bridge movable contact 2c. A lead wire that leads to the voltage dividing circuit is connected, and the arc voltage generated between the circuit contacts during the opening operation of the mechanical switch 2 is taken out to the gate drive circuit 9. For this reason, the wiring work of the lead wire becomes difficult due to the structural constraints of the mechanical switch 2 (for example, a small electromagnetic contactor), and the lead wire interferes to open and close the bridge movable contact 2c. May interfere with movement.

  On the other hand, in Example 4 of FIG. 9, the circuit contact of the mechanical switch 2 is divided into two poles, and the connection part (point A in the figure) between the contacts is connected to the voltage dividing circuit of the gate drive circuit. The lead wire 91 is connected. Thereby, it is possible to wire-connect the lead wire 91 to an external connection terminal (screw terminal) provided for each pole contact of the mechanical switch 2 (for example, a two-pole electromagnetic contactor). Unnecessary interference with the movable contact of the mechanical switch 2 can be prevented.

DESCRIPTION OF SYMBOLS 1 DC main circuit 2 Mechanical switch 21 Circuit contact 21-1 to 21-3 Circuit contact of 3 pole type electromagnetic switch 3 Semiconductor switch (bidirectional switch)
4-1, 4-2 Reverse blocking IGBT
7-1, 7-2 Overvoltage suppression element 8-1, 8-2 Capacitor 9 Gate drive circuit

Claims (1)

A switch applied to a circuit in which the current direction is reversed in both forward and reverse directions, wherein a bidirectional semiconductor switch is connected in parallel to a circuit contact of a mechanical switch connected to the circuit, and a circuit current is generated when the mechanical switch is opened. In a switch that commutates the current to the semiconductor switch and extinguishes the arc generated between the contacts of the mechanical switch, and then shuts off the current by controlling the semiconductor switch to be OFF,
As the semiconductor switch, a bidirectional switch formed by connecting two reverse blocking IGBTs (RB-IGBT: Reverse Blocking Insulated Gate Bipolar Transistors) having reverse withstand voltage performance in reverse parallel is connected in parallel to the mechanical switch. Then, during the opening operation of the mechanical switch, the arc voltage generated between the circuit contacts is applied to the gate of the reverse blocking IGBT to commutate the main circuit current to the semiconductor switch, and then the semiconductor switch is turned on. The circuit current is cut off by OFF control, and a three-pole switch with three sets of circuit contacts is used as the mechanical switch, and the bidirectional switch is connected in parallel to the circuit contact with one of the main contacts as the main contact. The switch is characterized in that the remaining two-pole circuit contacts are inserted and connected to the forward and return paths of the main circuit as disconnecting contacts .