Switchgear

Abstract

The present invention provides a switch device. In a DC circuit breaker that mechanically shuts off a vacuum circuit breaker and a gas circuit breaker when an overcurrent occurs and then shuts off an IGBT, since the period until the vacuum circuit breaker and the gas circuit breaker are mechanically shut off is long, the current flowing through the IGBT increases, so the current capacity of the IGBT must be increased to a level that is not saturated when an overcurrent occurs, resulting in increased costs and larger devices. The switch device that connects or disconnects an input terminal and an output terminal comprises: a mechanical switch unit and a first semiconductor switch unit, which are connected in series between the input terminal and the output terminal; a second semiconductor switch unit, which is connected in parallel with the mechanical switch unit and the first semiconductor switch unit between the input terminal and the output terminal; and a switch control unit, which controls the timing of turning on and off the first semiconductor switch unit and the second semiconductor switch unit, and the timing of opening and closing the mechanical switch unit.

Description

Technical Field

[0001] The invention relates to a switch device. Background Art

[0002] The following technology is known: in a switch having a mechanical switch and a semiconductor switch connected in parallel with each other, the mechanical switch and the semiconductor switch are usually turned on to make the current flow to the mechanical switch side, and when the current is cut off, the semiconductor switch is turned off after the mechanical switch is turned off (for example, refer to Patent Documents 1 and 2). In addition, the following technology is known: a DC circuit breaker is provided with: a mechanical switch including a gas circuit breaker and a vacuum circuit breaker; a forced commutation circuit connected in parallel with the vacuum circuit breaker; a semiconductor switch such as an IGBT connected in parallel with the mechanical switch, in which the current is usually made to flow to the mechanical switch, and when the current is cut off, a current in the opposite direction to the direction of the DC current flowing through the vacuum circuit breaker is flowed from the forced commutation circuit, thereby generating a current zero point in the vacuum circuit breaker and putting the vacuum circuit breaker in a non-conducting state, thereby commutating the current from the mechanical switch to the IGBT, and after the current flowing through the gas circuit breaker disappears, the gas circuit breaker is turned off and the IGBT is put in a non-conducting state (for example, refer to Patent Document 3).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. WO2011 / 034140

[0006] Patent Document 2: Japanese Patent Application Publication No. 2017-191764

[0007] Patent Document 3: International Publication No. WO2016 / 047209 Summary of the invention

[0008] Technical issues

[0009] According to the above-mentioned DC circuit breaker, although arcing in the gas circuit breaker can be basically avoided when an overcurrent occurs, the IGBT is turned off after the vacuum circuit breaker and the gas circuit breaker are mechanically turned off. During the shutdown period of the DC circuit breaker, which includes the period until the vacuum circuit breaker and the gas circuit breaker are mechanically turned off, the current flowing through the IGBT increases because the period until the vacuum circuit breaker and the gas circuit breaker are mechanically turned off is long. As a result, the collector current of the IGBT is saturated when it is less than five times the rated current, and its forward voltage drop is the largest and rises to the equivalent of the power supply voltage. Therefore, in the above-mentioned DC circuit breaker, in order to make the IGBT have the ability to cut off overcurrent, the current capacity of the IGBT must be increased to a level that is not saturated even when an overcurrent occurs, resulting in increased costs and large-scale devices.

[0010] Technical Solution

[0011] The switch device for connecting or disconnecting the input terminal and the output terminal may include a mechanical switch unit, a first semiconductor switch unit, a second semiconductor switch unit, and a switch control unit. The mechanical switch unit and the first semiconductor switch unit may be connected in series between the input terminal and the output terminal. The second semiconductor switch unit may be connected in parallel with the mechanical switch unit and the first semiconductor switch unit between the input terminal and the output terminal. The switch control unit may control the on / off timing of each of the first semiconductor switch unit and the second semiconductor switch unit, and the timing of opening and closing the mechanical switch unit.

[0012] The switch device may also include a current detection unit arranged between the input terminal and the output terminal. The switch control unit may include a protection circuit, a pulse distribution circuit, and a drive circuit. The protection circuit may output a shutdown command when an overcurrent is detected based on a signal from the current detection unit. The pulse distribution circuit may open and close the mechanical switch unit based on a signal from the outside, and output a pulse signal pre-set to respectively turn on and off the first semiconductor switch unit and the second semiconductor switch unit. When a shutdown command is received from the protection circuit, the mechanical switch unit is closed regardless of the signal from the outside, and a pulse signal pre-set to respectively turn off the first semiconductor switch unit and the second semiconductor switch unit is output. The drive circuit may output a signal for opening and closing the mechanical switch unit and a gate voltage for respectively turning on and off the first semiconductor switch unit and the second semiconductor switch unit based on the pulse signal received from the pulse distribution circuit.

[0013] The first semiconductor switch portion may have a withstand voltage higher than an on-state voltage of the second semiconductor switch portion.

[0014] The first semiconductor switch unit may include a plurality of first semiconductor switches connected in parallel between an input terminal and an output terminal. The second semiconductor switch unit may include a plurality of second semiconductor switches connected in series between an input terminal and an output terminal. The withstand voltage of each of the plurality of first semiconductor switches is higher than the sum of the on-state voltages of the plurality of second semiconductor switches.

[0015] When the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit are all in the on state, when the input terminal and the output terminal are switched from a connected state to a disconnected state, the switch control unit can shut down the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit in that order.

[0016] When switching the connection state between the input terminal and the output terminal to the disconnection state, the switch control unit may turn off the mechanical switch unit after turning off the first semiconductor switch unit and then when the current of the first semiconductor switch unit becomes less than a predetermined value.

[0017] When the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit are all in the off state, when switching the input terminal and the output terminal from the disconnected state to the connected state, the switch control unit can be turned on in the order of the second semiconductor switch unit, the mechanical switch unit, and the first semiconductor switch unit.

[0018] The switch control unit may turn on the mechanical switch unit after turning on the second semiconductor switch unit and then, when the potential difference between the input terminal and the output terminal becomes equal to or smaller than a reference.

[0019] The switch device may include a mechanical switching switch, a first semiconductor switch unit, a second semiconductor switch unit, a third semiconductor switch unit, and a switch control unit. The mechanical switching switch may switch the connection state between the first input terminal and the output terminal, and the connection state between the second input terminal and the output terminal. The first semiconductor switch unit may be connected in series with the mechanical switching switch between the first input terminal and the output terminal, and between the second input terminal and the output terminal. The second semiconductor switch unit may be connected in parallel with the mechanical switching switch and the first semiconductor switch unit between the first input terminal and the output terminal. The third semiconductor switch unit may be connected in parallel with the mechanical switching switch and the first semiconductor switch unit between the second input terminal and the output terminal. The switch control unit may control the on-off moment of each of the first semiconductor switch unit, the second semiconductor switch unit, and the third semiconductor switch unit, and the moment of opening and closing the mechanical switching switch.

[0020] When the first semiconductor switch unit and the second semiconductor switch unit are in a conductive state and the mechanical switching switch is in a state connecting the first input terminal and the first semiconductor switch unit, when the first input terminal and the output terminal are switched from a connected state to a disconnected state and the second input terminal and the output terminal are switched from a disconnected state to a connected state, the switch control unit may turn off the first semiconductor switch unit, then switch the mechanical switching switch to a state connecting the second input terminal and the first semiconductor switch unit, then turn off the second semiconductor switch unit and turn on the third semiconductor switch unit, and then turn on the first semiconductor switch unit.

[0021] When the first semiconductor switch unit and the second semiconductor switch unit are in an on state and the mechanical switching switch is in a state connecting the first input terminal and the first semiconductor switch unit, when the first input terminal and the output terminal are switched from a connected state to a disconnected state and the second input terminal and the output terminal are switched from a disconnected state to a connected state, the switch control unit may turn off the first semiconductor switch unit, then switch the mechanical switching switch to a state in which neither the first input terminal nor the first semiconductor switch unit is connected, then turn off the second semiconductor switch unit and turn on the third semiconductor switch unit, then switch the mechanical switching switch to a state in which the second input terminal and the first semiconductor switch unit are connected, and then turn on the first semiconductor switch unit.

[0022] After turning on the third semiconductor switch unit, the switch control unit may switch the mechanical switch to a state connecting the second input terminal and the first semiconductor switch unit when the potential difference between the second input terminal and the output terminal becomes equal to or smaller than a reference.

[0023] The first semiconductor switch unit may include a plurality of first semiconductor switches. The plurality of first semiconductor switches may be connected in reverse series between the input terminal and the output terminal, and each of the plurality of first semiconductor switches may include a group of semiconductor switch elements and diodes connected in reverse parallel between the input terminal and the output terminal. The switch device may also include a diode bridge. The diode bridge may be connected in parallel with the second semiconductor switch unit between the input terminal and the output terminal.

[0024] The first semiconductor switch unit may include a plurality of first semiconductor switches. The plurality of first semiconductor switches are connected in reverse series between the first input terminal and the output terminal, and each of the plurality of first semiconductor switches includes a group of semiconductor switch elements and diodes connected in reverse parallel between the first input terminal and the output terminal. The switch device may also include a first diode bridge and a second diode bridge. The first diode bridge may be connected in parallel with the second semiconductor switch unit between the first input terminal and the output terminal. The second diode bridge may be connected in parallel with the third semiconductor switch unit between the second input terminal and the output terminal.

[0025] The first semiconductor switch part may include a MOSFET, and the second semiconductor switch part may include at least any one of an IGBT, a GTO thyristor, and a WBG semiconductor.

[0026] The first semiconductor switch part may include a MOSFET, and at least any one of the second semiconductor switch part and the third semiconductor switch part may include at least any one of an IGBT, a GTO thyristor, and a WBG semiconductor.

[0027] It should be noted that the above summary of the invention does not list all the features of the present invention. In addition, sub-combinations of these features will also constitute inventions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is a schematic circuit diagram of the switch device 10 according to the first embodiment.

[0029] Figure 2 1 is a timing chart showing the operation of the switch unit 100 according to the first embodiment.

[0030] Figure 3 2 is a schematic circuit diagram of a switch unit 200 according to the second embodiment.

[0031] Figure 4 2 is a schematic circuit diagram of a switch unit 300 according to the third embodiment.

[0032] Figure 5 It is a timing chart showing the operation of the switch unit 300 according to the third embodiment.

[0033] Explanation of symbols

[0034] 5 control device, 10 switch device, 21 first terminal, 22 second terminal, 23 third terminal, 25 control terminal, 30 current detection unit, 40 control circuit, 41 protection circuit, 42 pulse distribution circuit, 43 drive circuit, 100, 200, 300 switch unit, 110, 310 mechanical switch unit, 120, 220 first semiconductor switch unit, 130, 230 second semiconductor switch unit, 221, 222 first semiconductor switch, 231 second semiconductor switch, 232 capacitor, 240, 340 diode bridge, 241, 242, 243, 244, 341, 342, 343, 344 diode, 330 third semiconductor switch unit, 331 third semiconductor switch, 332 capacitor. DETAILED DESCRIPTION

[0035] Although the present invention is described below by the embodiments of the invention, the following embodiments do not limit the invention involved in the claims. In addition, all combinations of the features described in the embodiments are not necessarily required for the technical solution of the invention. It should be noted that there are cases where the same or similar parts are marked with the same figure mark in the drawings and repeated descriptions are omitted.

[0036] Figure 1 1 is a schematic circuit diagram of the switch device 10 according to the first embodiment. In the figure, arrows with black front ends indicate the input and output directions of control signals, and arrows with blank front ends indicate the flow direction of power. The same setting is applied to the following figures.

[0037] The switch device 10 includes a first terminal 21, a second terminal 22, a control terminal 25, a switch unit 100, a current detection unit 30, and a control circuit 40. The first terminal 21 is an example of an input terminal, and the second terminal 22 is an example of an output terminal. The switch device 10 connects or disconnects the first terminal 21 and the second terminal 22, thereby conducting or disconnecting a DC current that is intended to flow from the first terminal 21 to the second terminal 22. The switch device 10 can be applied to a distribution board that handles DC current, and is controlled by an external control device 5 via the control terminal 25. In the case of commercial use, the switch device 10 is applied with a high DC voltage of 400V or 800V, for example.

[0038] The switch unit 100 includes a mechanical switch unit 110 , a first semiconductor switch unit 120 , and a second semiconductor switch unit 130 .

[0039] The mechanical switch unit 110 is connected between the first terminal 21 and the second terminal 22. The mechanical switch unit 110 includes a mechanical relay as an example, and has a metal contact. The mechanical switch unit 110 may not have an arc-eliminating structure. Since the mechanical switch unit 110 makes the metal conductors contact or separate, the on-resistance is greatly reduced compared to both the first semiconductor switch unit 120 and the second semiconductor switch unit 130, and there is almost no current conduction loss even when a large current is conducted. Therefore, the mechanical switch unit 110 does not require a cooling heat sink or the like for cooling the heat generated by power loss. In the following description, the opening and closing of the mechanical switch unit 110 is referred to as turning the mechanical switch unit 110 on and off.

[0040] The first semiconductor switch unit 120 is connected in series with the mechanical switch unit 110 between the first terminal 21 and the second terminal 22. The switching speed is faster than that of the mechanical switch unit 110 and the second semiconductor switch unit 130. As an example, the first semiconductor switch unit 120 includes a low-voltage MOSFET with a very low on-resistance of several microΩ when the switching speed is tens of ns and the withstand voltage is tens of V. The low-voltage MOSFET includes a built-in parasitic diode or a reverse-parallel diode. The drain of the low-voltage MOSFET of the first semiconductor switch unit 120 is connected to the mechanical switch unit 110, the source is connected to the second terminal 22, and the gate is connected to the control circuit 40.

[0041] The second semiconductor switch unit 130 is connected between the first terminal 21 and the second terminal 22 in parallel with the mechanical switch unit 110 and the first semiconductor switch unit 120. Compared with the mechanical switch unit 110, the second semiconductor switch unit 130 can cut off the current at a high speed.

[0042] The withstand voltage of the first semiconductor switch unit 120 is lower than the withstand voltage of the second semiconductor switch unit 130, and higher than the on-voltage of the second semiconductor switch unit 130. The on-voltage of the second semiconductor switch unit 130 is a voltage generated between the main terminals of the second semiconductor switch unit 130 when the second semiconductor switch unit 130 is turned on in the on state.

[0043] In addition, the on-state voltage of the second semiconductor switch unit 130 is higher than the sum of the on-state voltages of the mechanical switch unit 110 and the first semiconductor switch unit 120. As an example, the second semiconductor switch unit 130 includes an IGBT. The second semiconductor switch unit 130 may include a GTO thyristor, a WBG semiconductor, and the like. The collector of the IGBT of the second semiconductor switch unit 130 is connected to the first terminal 21, the emitter is connected to the second terminal 22, and the gate is connected to the control circuit 40.

[0044] The current detection unit 30 is provided between the first terminal 21 and the second terminal 22, and as an example, is provided on the first terminal 21 side, that is, provided on the input side of the direct current, detects the current flowing between the first terminal 21 and the second terminal 22, and outputs a signal indicating the current value to the control circuit 40. The current detection unit 30 may be an ammeter connected in series with the switch unit 100 between the first terminal 21 and the second terminal 22. In addition, the current detection unit 30 may be a current mutual inductance type current sensor that detects the current flowing between the first terminal 21 and the second terminal 22 in a non-contact manner.

[0045] The control circuit 40 includes a protection circuit 41, a pulse distribution circuit 42, and a drive circuit 43. The control circuit 40 controls the timing of turning on and off the first semiconductor switch unit 120 and the second semiconductor switch unit 130 of the switch unit 100, and the timing of opening and closing the mechanical switch unit 110, based on the control signal sent from the control device 5. The control circuit 40 is an example of a switch control unit. The control circuit 40, as a control computer including a CPU such as a microcontroller, can function as the following parts by executing a switch program. Alternatively, the control circuit 40 can also be implemented by a dedicated circuit or a programmable circuit.

[0046] Regarding the mechanical switch section 110, when the DC current is conducted in the switch section 100, that is, in a normal state, the control circuit 40 controls the mechanical switch section 110 to be closed and the DC current is conducted. In addition, when the DC current is cut off in the switch section 100, the control circuit 40 controls the mechanical switch section 110 to be turned off after the DC current that has been conducted in the mechanical switch section 110 is commutated to the second semiconductor switch section 130. Since the control circuit 40 controls the mechanical switch section 110 in this way, no arc is generated in the mechanical switch section 110. In addition, in the state where the mechanical switch section 110 is already closed, since the voltage between the first terminal 21 and the second terminal 22 is only about several volts to several tens of volts during the period when the first semiconductor switch section 120 and the second semiconductor switch section 130 are in the conducting state, the control circuit 40 can instead cut off the current by using the mechanical switch section 110 by turning off the mechanical switch section 110 without performing the above-mentioned commutation. In this case, the switch unit 100 may additionally include a structure for protecting the mechanical switch unit 110 from an arc generated in the mechanical switch unit 110 .

[0047] Regarding the first semiconductor switch unit 120, under normal circumstances, the control circuit 40 controls the first semiconductor switch unit 120 to be in an on state and conduct the direct current. In addition, when the direct current is cut off in the switch unit 100, the control circuit 40 controls the first semiconductor switch unit 120 to be turned off before the mechanical switch unit 110 and the second semiconductor switch unit 130, thereby commutating the direct current flowing to the first semiconductor switch unit 120 side to the second semiconductor switch unit 130 side.

[0048] Regarding the second semiconductor switch section 130, under normal circumstances, the control circuit 40 controls the second semiconductor switch section 130 so as to be in the on state. Moreover, since the on-voltage of the second semiconductor switch section 130 is higher than the sum of the on-voltages of the mechanical switch section 110 and the first semiconductor switch section 120, almost no direct current flows to the second semiconductor switch section 130. In addition, when the direct current is cut off in the switch section 100, the control circuit 40 controls the second semiconductor switch section 130 so as to turn off the direct current flowing through the first semiconductor switch section 120 after the direct current is commutated to the second semiconductor switch section 130 and flows through the second semiconductor switch section 130. It should be noted that, under normal circumstances, the control circuit 40 can keep the second semiconductor switch unit 130 in an off state while a direct current is flowing through the first semiconductor switch unit 120 side, and when the direct current is cut off in the switch unit 100, the control circuit 40 can control the commutation and cutting of the direct current in the same manner as described above by turning off the first semiconductor switch unit 120 after turning on the second semiconductor switch unit 130.

[0049] The protection circuit 41 receives a control signal for conducting a normal direct current in the switch unit 100 from the external control device 5 via the control terminal 25, and outputs the control signal to the pulse distribution circuit 42. The protection circuit 41 receives a signal from the current detection unit 30 at any time, and detects an overcurrent based on the signal from the current detection unit 30. As an example, the protection circuit 41 detects an overcurrent by judging whether the current value indicated by the signal from the current detection unit 30 is greater than a preset overcurrent setting value lim. When an overcurrent is detected, the protection circuit 41 outputs a shutdown command to the pulse distribution circuit 42. It should be noted that when the switch device 10 does not include the current detection unit 30, the protection circuit 41 may detect the current value on the first terminal 21 side of the switch device 10, that is, the input side of the direct current. In this case, the protection circuit 41 may include a magnetic sensor as an example to detect the current value. It should be noted that the protection circuit 41 may stop supplying the control signal to the pulse distribution circuit 42 instead of outputting the shutdown signal.

[0050] The pulse distribution circuit 42 opens and closes the mechanical switch section 110 based on the control signal from the external control device 5 inputted via the protection circuit 41, and outputs a pulse signal preset for turning on and off the first semiconductor switch section 120 and the second semiconductor switch section 130 to the drive circuit 43. When the pulse distribution circuit 42 receives a turn-off instruction from the protection circuit 41, it closes the mechanical switch section 110 and outputs a pulse signal preset for turning off the first semiconductor switch section 120 and the second semiconductor switch section 130 to the drive circuit 43, regardless of the control signal from the external control device 5. The pulse distribution circuit 42 outputs a pulse signal to the drive circuit 43, to which a predetermined delay time or time difference is added to the control signal from the external control device 5 inputted from the protection circuit 41. As a result, the opening and closing operation of the mechanical switch section 110 and the timing of the turning on and off operation of the first semiconductor switch section 120 and the second semiconductor switch section 130 are mutually staggered.

[0051] The drive circuit 43 outputs a signal for opening and closing the mechanical switch unit 110 and a gate voltage for turning on and off the first semiconductor switch unit 120 and the second semiconductor switch unit 130 respectively based on the pulse signal received from the pulse distribution circuit 42, that is, at a time according to the delay time added to the above-mentioned control signal.

[0052] Figure 2 It is a timing chart showing the operation of the switch unit 100 according to the first embodiment. Figure 2 The horizontal direction is the passage of time, and the vertical direction is in order from the top to show the overall current, the current on the second semiconductor switch unit 130 side, the current on the first semiconductor switch unit 120 side, the on / off state of the second semiconductor switch unit 130, the on / off state of the mechanical switch unit 110, and the on / off state of the first semiconductor switch unit 120. In addition, Figure 2 The passage of time is mainly divided into three periods: period (I), period (II), and period (III) from the left.

[0053] Period (I) is a period during which the switch unit 100 transitions from a state in which the DC current is cut off to a state in which the DC current is conducted. Period (II) is a period during which the DC current is normally conducted in the switch unit 100. Period (III) is a period during which the switch unit 100 transitions from a state in which the DC current is conducted to a state in which the DC current is cut off. Figure 2 In the example, the period (II) is shortened only for the sake of clarity. Figure 2In the timing sequence shown, the period before the period (I) and the period after the period (III) are periods in which the switch unit 100 cuts off the DC current, and the period not shown may arbitrarily include the period (I), the period (II) and the period (III).

[0054] At the time t1 at the beginning of the period (I), the control circuit 40 controls the gate voltage of the IGBT of the second semiconductor switch unit 130, which are all in the off state, for the mechanical switch unit 110, the first semiconductor switch unit 120, and the second semiconductor switch unit 130, and only the second semiconductor switch unit 130 is turned on. Since the IGBT is a semiconductor switch element that can perform a switching operation at a relatively high speed, it can quickly become a conducting state, and the overall conduction operation of the switch device 10 can be accelerated. If only the second semiconductor switch unit 130 becomes a conducting state, the DC current starts to flow only to the second semiconductor switch unit 130 side.

[0055] The next moment t2 of the period (I) has a time difference Δt1 relative to the moment t1. The time difference Δt1 only needs to be ensured to be the time required for the IGBT of the second semiconductor switch unit 130 to be turned on, that is, it only needs to be ensured to be the time until the turn-on action is completed and the steady-state DC current is connected to the IGBT. As an example, the time difference Δt1 is about 1μ second to 2μ second. At the moment t2, the mechanical switch unit 110 is turned on by the control circuit 40. At this time, because the first semiconductor switch unit 120 connected in series with the mechanical switch unit 110 is still in the off state, even if the mechanical switch unit 110 is turned on, there is still no DC current flowing on the first semiconductor switch unit 120 side, and the DC current only flows to the second semiconductor switch unit 130 side. Therefore, no arc is generated in the mechanical switch unit 110. Furthermore, by setting the time difference Δt1, even if the mechanical switch unit 110 is turned on, the DC voltage applied to the first semiconductor switch unit 120 is the on-state voltage of the IGBT of the second semiconductor switch unit 130 and is only about tens of volts, so a low-voltage MOSFET can be used in the first semiconductor switch unit 120.

[0056] The first time t3 of period (II) is delayed by a time td relative to time t1. on At time t3, the control circuit 40 controls the gate voltage of the low withstand voltage MOSFET of the first semiconductor switch unit 120, and turns on the first semiconductor switch unit 120. Because the sum of the on-voltage of the mechanical switch unit 110 and the first semiconductor switch unit 120 is lower than the on-voltage of the second semiconductor switch unit 130, at time t3, the DC current flowing on the second semiconductor switch unit 130 side is commutated to the first semiconductor switch unit 120 side, and the DC current hardly flows to the second semiconductor switch unit 130 side. Delay time td onThe difference from the time difference Δt1 only needs to be ensured to be the time required for closing the mechanical switch unit 110. Although if the first semiconductor switch unit 120 is turned on before the mechanical switch unit 110 is closed, an arc will be generated when the mechanical switch unit 110 is closed, the above control can reliably avoid the arc from being generated in the mechanical switch unit 110.

[0057] During period (II), the ratio of the DC current flowing through the first semiconductor switch unit 120 side to the DC current flowing through the second semiconductor switch unit 130 side corresponds to the ratio of the sum of the on-voltages of the mechanical switch unit 110 and the first semiconductor switch unit 120 to the on-voltage of the second semiconductor switch unit 130. Therefore, by, for example, changing the number of semiconductor switch elements connected in parallel, the above-mentioned DC current ratio can be adjusted. For example, by connecting a plurality of low-voltage MOSFETs in parallel as the first semiconductor switch unit 120 to reduce the on-resistance of the first semiconductor switch unit 120, the DC current flowing through the second semiconductor switch unit 130 side can be reduced. In addition, in the second semiconductor switch unit 130, by utilizing the trade-off relationship between the switching speed and the on-resistance, a semiconductor switch element with a priority on the switching speed is selected, and the on-resistance is intentionally increased, thereby reducing the DC current flowing through the second semiconductor switch unit 130 side.

[0058] At the beginning time t4 of the period (III), for the mechanical switch section 110, the first semiconductor switch section 120, and the second semiconductor switch section 130, which are all in the on state, the gate voltage of the low withstand voltage MOSFET of the first semiconductor switch section 120 is controlled by the control circuit 40, and only the first semiconductor switch section 120 is turned off. The low withstand voltage MOSFET can be quickly turned off because the switching speed is several tens of ns. By turning the first semiconductor switch section 120 into the off state, the first semiconductor switch section 120 side is completely cut off, and the DC current flowing on the first semiconductor switch section 120 side is commutated to the second semiconductor switch section 130 side. By keeping the mechanical switch section 110 and the second semiconductor switch section 130 in the on state and turning off the first semiconductor switch section 120, the DC voltage applied to the first semiconductor switch section 120 is the on voltage of the IGBT of the second semiconductor switch section 130, which is only about several tens of V, so the low withstand voltage MOSFET can still be used in the first semiconductor switch section 120.

[0059] The next moment t5 of period (III) has a time difference Δt2 relative to the moment t4. The time difference Δt2 only needs to be ensured to be the time required to turn off the low-voltage MOSFET of the first semiconductor switch unit 120, that is, it only needs to be ensured to be the time until the shutdown action is completed and the DC current flowing through the first semiconductor switch unit 120 side is commutated to the second semiconductor switch unit 130 side. As an example, the time difference Δt2 is about 1μ second to 2μ second. At the moment t5, the mechanical switch unit 110 is turned off by the control circuit 40. At this time, because no DC current has already flowed on the first semiconductor switch unit 120 side, no arc is generated in the mechanical switch unit 110.

[0060] The next time t6 of period (III) is delayed by time td relative to time t4. off At time t6, the control circuit 40 controls the gate voltage of the IGBT of the second semiconductor switch unit 130, and turns off the second semiconductor switch unit 130, thereby completely cutting off the DC current flowing through the switch unit 100. Since the IGBT is a semiconductor switch element capable of relatively high-speed switching, it can quickly become an off state, and when an overcurrent occurs, the overall turn-off operation of the switch device 10 can be accelerated.

[0061] Delay time td off The difference from the time difference Δt2 only needs to be ensured to be the time required for the mechanical switch unit 110 to turn off. If the semiconductor switch unit 130 is turned off before the mechanical switch unit 110 turns off, although the high voltage of the system is applied to the low withstand voltage MOSFET of the first semiconductor switch unit 120 via the first terminal 21, which may cause overvoltage damage, the above control can reliably avoid overvoltage damage to the low withstand voltage MOSFET.

[0062] According to the switch device 10 of the first embodiment described above, when the first semiconductor switch unit 120, the mechanical switch unit 110, and the second semiconductor switch unit 130 are in the off state and the connection between the first terminal 21 and the second terminal 22 is switched from the disconnected state to the connected state, the second semiconductor switch unit 130, the mechanical switch unit 110, and the first semiconductor switch unit 120 are turned on in this order. In addition, according to the switch device 10, when the first semiconductor switch unit 120, the mechanical switch unit 110, and the second semiconductor switch unit 130 are in the on state and the connection between the first terminal 21 and the second terminal 22 is switched from the connected state to the disconnected state, the first semiconductor switch unit 120, the mechanical switch unit 110, and the second semiconductor switch unit 130 are turned off in this order.

[0063] Thus, the switch device 10 can use a low-voltage MOSFET with a fast switching speed and extremely low on-resistance in the first semiconductor switch unit 120. Generally, since the direct current flows between the mechanical switch unit 110 and the first semiconductor switch unit 120, the current conduction loss can be suppressed. In addition, since the mechanical switch unit 110 does not need a structure to remove the arc, it can be miniaturized and cost-effective. In addition, since there is no loss on the metal contact caused by the arc in the mechanical switch unit 110, the service life can be extended. In addition, by configuring so that the mechanical switch unit 110 does not generate an arc, the disconnection time can be shortened compared with the case where the direct current is cut off by the cooling effect of hydrogen and the arc extension effect of the magnetic field in the mechanical relay. Thus, when the switch device 10 cuts off a large current, the period from the first semiconductor switch unit 120 being turned off to the second semiconductor switch unit 130 being turned off after the mechanical switch unit 110 is turned off is shortened, and the current rise in the second semiconductor switch unit 130 is suppressed. Therefore, the switch device 10 can reduce the current capacity of the second semiconductor switch unit 130 , and can be miniaturized and reduced in cost.

[0064] In the first embodiment described above, the switch device 10 is described as being controlled by the external control device 5. Alternatively, the switch device 10 may be integrated so as to include the control device 5 internally. The same applies to the following embodiments.

[0065] In the above first embodiment, the case where the first semiconductor switch unit 120 and the second semiconductor switch unit 130 of the switch device 10 each include a separate semiconductor switch element is described. Alternatively, the first semiconductor switch unit 120 may also include a plurality of first semiconductor switches connected in parallel between the first terminal 21 and the second terminal 22. Thus, as the first semiconductor switch unit 120, a first semiconductor switch with a smaller rated current can be used, and it can be miniaturized and cost-effective, and redundancy can be improved. In addition, the second semiconductor switch unit 130 may also include a plurality of second semiconductor switches connected in series between the first terminal 21 and the second terminal 22. Thus, as the second semiconductor switch unit 130, a second semiconductor switch with a smaller withstand voltage can be used, and it can be miniaturized and cost-effective. In addition, in this case, the withstand voltage of each of the plurality of first semiconductor switches can be lower than the withstand voltage of each of the plurality of second semiconductor switches, and can be higher than the sum of the on-state voltages of the plurality of second semiconductor switches. In addition, a margin can also be set between these contrasting voltages. Thus, the on-off action can be controlled in the same manner as the switch device 10 of the first embodiment. The same is true for the following embodiments.

[0066] In the first embodiment above, the switch device 10 has been described as shifting the timing by the time difference Δt1 after turning on the second semiconductor switch unit 130 when switching the first terminal 21 and the second terminal 22 from the disconnected state to the connected state, and turning on the mechanical switch unit 110 by the control circuit 40. Alternatively or additionally, the switch device 10 may include a voltmeter for detecting the potential difference between the first terminal 21 as the input side of the second semiconductor switch unit 130 and the second terminal 22 as the output side, and when switching the first terminal 21 and the second terminal 22 from the disconnected state to the connected state, after turning on the second semiconductor switch unit 130, the mechanical switch unit 110 is turned on when the potential difference between the first terminal 21 and the second terminal 22 detected by the voltmeter becomes less than a reference. Thus, by setting the reference to the on-voltage of the IGBT of the second semiconductor switch unit 130, for example, when the mechanical switch unit 110 is turned on, it is possible to ensure that the DC voltage applied to the first semiconductor switch unit 120 is lower than the on-voltage, and it is possible to reliably prevent overvoltage damage from occurring in the first semiconductor switch unit 120. The same applies to the following embodiments.

[0067] In the first embodiment above, the switch device 10 has been described as shifting the timing by the time difference Δt2 after turning off the first semiconductor switch unit 120 when switching the first terminal 21 and the second terminal 22 from the connection state to the disconnection state, and turning off the mechanical switch unit 110 by the control circuit 40. Alternatively or additionally, the switch device 10 may include an ammeter for detecting the current flowing through the first semiconductor switch unit 120, and when switching the first terminal 21 and the second terminal 22 from the connection state to the disconnection state, after turning off the first semiconductor switch unit 120, the mechanical switch unit 110 is turned off based on the current of the first semiconductor switch unit 120 detected by the ammeter becoming less than a predetermined value.

[0068] Figure 3 : is a schematic circuit diagram of the switch unit 200 of the second embodiment. The switch device 10 of this embodiment can be applied to a distribution board that processes AC current, for example, an AC voltage of 100V or 200V is applied in commercial use, and an AC voltage of 3.3kV or 6.6kV is applied when connected to a high-voltage line. The switch device 10 of this embodiment connects or disconnects the first terminal 21 and the second terminal 22, thereby conducting or disconnecting the AC current flowing from the first terminal 21 to the second terminal 22.

[0069] The switch device 10 of this embodiment is different from the switch device 10 of the first embodiment in that it has a switch unit 200 instead of the switch unit 100, and has the same components as those of the switch device 10 of the first embodiment. In this embodiment, the same reference numerals are used for the same components as those of the switch device 10 of the first embodiment, and repeated descriptions are omitted. The same is also true for the following embodiments.

[0070] The switch unit 200 includes a mechanical switch unit 110 , a first semiconductor switch unit 220 , a diode bridge 240 , and a second semiconductor switch unit 230 .

[0071] The first semiconductor switch unit 220 is connected in series with the mechanical switch unit 110 between the first terminal 21 and the second terminal 22. The first semiconductor switch unit 220 includes a first semiconductor switch 221 and a first semiconductor switch 222 connected in reverse series between the first terminal 21 and the second terminal 22. The first semiconductor switch 221 and the first semiconductor switch 222 each include a group of semiconductor switch elements and diodes connected in reverse parallel between the first terminal 21 and the second terminal 22. As an example, the group of semiconductor switch elements and diodes includes a low withstand voltage MOSFET and a group of parasitic diodes built into the low withstand voltage MOSFET or a diode connected in reverse parallel with the low withstand voltage MOSFET, similar to the first semiconductor switch unit 120 of the first embodiment. The drain of the low withstand voltage MOSFET of the first semiconductor switch 221 is connected to the mechanical switch unit 110, the source is connected to the source of the low withstand voltage MOSFET of the first semiconductor switch 222, and the drain of the low withstand voltage MOSFET of the first semiconductor switch 222 is connected to the second terminal 22. In addition, the gates of the first semiconductor switch 221 and the first semiconductor switch 222 are also connected to the control circuit 40.

[0072] The diode bridge 240 is connected in parallel with the mechanical switch unit 110 and the first semiconductor switch unit 220 between the first terminal 21 and the second terminal 22. The diode bridge 240 includes a diode 241, a diode 242, a diode 243, and a diode 244. The diode bridge 240 performs full-wave rectification using the four diodes 241, etc., thereby forming a rectification circuit that allows AC current to flow in only one direction.

[0073] Between the first terminal 21 and the second terminal 22, the second semiconductor switch unit 230 is connected in parallel with the diode bridge 240 on the rectifier side of the diode bridge 240. The second semiconductor switch unit 230 includes a second semiconductor switch 231 and a capacitor 232 connected in parallel between the first terminal 21 and the second terminal 22. The capacitor 232 is a capacitor for soft switching, forming a so-called buffer circuit. The second semiconductor switch 231 has a group of semiconductor switch elements and diodes connected in reverse parallel between the first terminal 21 and the second terminal 22. As an example, the group of semiconductor switch elements and diodes includes an IGBT and a group of diodes connected in reverse parallel to the IGBT. The collector of the IGBT of the second semiconductor switch unit 230 is connected to the second terminal 22, the emitter is connected to the first terminal 21, and the gate is connected to the control circuit 40.

[0074] Since the IGBT is connected via the diode bridge 240, it can be applied to either positive or negative current, that is, only one IGBT can be used to switch the AC current. This avoids increasing the number of expensive IGBTs, and enables miniaturization and cost reduction. In addition, in the case where the switch device 10 is a circuit breaker or the like and a relatively large current is connected, if the switch unit 200 is not formed via the diode bridge 240, two IGBTs are required. Therefore, since two IGBTs with saturation characteristics corresponding to large currents are required, the cost increases. In this regard, according to the present embodiment, Figure 3 As shown in FIG. 1 , by configuring the switch unit 200 to be connected via the diode bridge 240 , the cost can be significantly reduced.

[0075] Regarding the first semiconductor switch unit 220, the control circuit 40 outputs a common control signal to the first semiconductor switch 221 and the first semiconductor switch 222, that is, the control is performed in such a manner that the on and off operations of the first semiconductor switch 221 and the first semiconductor switch 222 are linked. More specifically, under normal circumstances, the control circuit 40 controls the first semiconductor switch 221 and the first semiconductor switch 222 in such a manner that both are in the on state, thereby allowing the alternating current to flow through each low withstand voltage MOSFET side by so-called synchronous rectification not only when the alternating current flows from the drain to the source, but also when the alternating current flows from the source to the drain. Therefore, the current conduction loss of the first semiconductor switch unit 220 is still small. When the switch unit 200 cuts off the alternating current, the control circuit 40 controls the first semiconductor switch 221 and the first semiconductor switch 222 to be turned off together before the mechanical switch unit 110 and the second semiconductor switch unit 230, thereby commutating the alternating current flowing through the first semiconductor switch unit 220 side to the second semiconductor switch unit 230 side.

[0076] Regarding the second semiconductor switch unit 230, under normal circumstances, the control circuit 40 controls the second semiconductor switch unit 230 in an on state. In addition, since the on-voltage of the second semiconductor switch unit 230 is higher than the sum of the on-voltages of the mechanical switch unit 110 and the first semiconductor switch unit 220, the AC current hardly flows to the second semiconductor switch unit 230. In addition, when the switch unit 200 cuts off the AC current, the control circuit 40 controls the second semiconductor switch unit 230 to be turned off after the AC current flowing through the first semiconductor switch unit 220 is commutated to the second semiconductor switch unit 230 and flows through the second semiconductor switch unit 230. It should be noted that, under normal circumstances, the control circuit 40 can keep the second semiconductor switch unit 230 in the off state while the AC current is flowing on the first semiconductor switch unit 220 side, and when the switch unit 200 cuts off the AC current, the control circuit 40 can turn on the second semiconductor switch unit 230 and then turn off the first semiconductor switch unit 220, and control the commutation and cutting of the DC current in the same manner as described above.

[0077] According to the switch device 10 of the second embodiment described above, similarly to the switch device 10 of the first embodiment, when the first semiconductor switch unit 220, the mechanical switch unit 110, and the second semiconductor switch unit 230 are turned off, when the first terminal 21 and the second terminal 22 are switched from the disconnected state to the connected state, the second semiconductor switch unit 230, the mechanical switch unit 110, and the first semiconductor switch unit 220 are turned on in this order. In addition, according to the switch device 10, when the first terminal 21 and the second terminal 22 are switched from the connected state to the disconnected state, the first semiconductor switch unit 220, the mechanical switch unit 110, and the second semiconductor switch unit 230 are turned off in this order. Thus, the switch device 10 has the same effect as the switch device 10 of the first embodiment. Furthermore, since the switch device 10 includes the diode bridge 240 connected in parallel to the second semiconductor switch unit 230 , it can function as an AC bidirectional switch while avoiding an increase in the number of expensive IGBTs, thereby achieving miniaturization and cost reduction.

[0078] In the above second embodiment, the first semiconductor switch section 220 of the switch device 10 includes two first semiconductor switches 221 and a first semiconductor switch 222 connected in reverse series, and the second semiconductor switch section 230 includes a separate semiconductor switch element. Alternatively, the first semiconductor switch section 220 may also include a plurality of first semiconductor switches connected in parallel between the first terminal 21 and the second terminal 22. In addition, the second semiconductor switch section 230 may include a plurality of second semiconductor switches connected in series between the first terminal 21 and the second terminal 22. In addition, in this case, the withstand voltage of each of the plurality of first semiconductor switches may be lower than the withstand voltage of each of the plurality of second semiconductor switches, and may be higher than the sum of the conduction voltages of each of the plurality of second semiconductor switches. In addition, a margin may also be provided between these contrasting voltages. Thus, the switch device 10 has the same effect as the switch device 10 of the first embodiment.

[0079] Figure 4 : is a schematic circuit diagram of the switch unit 300 of the third embodiment. The switch device 10 of this embodiment can be applied to a distribution board that processes AC current, etc., as in the second embodiment, and can also be applied to switching between main power and backup power, etc. The switch device 10 of this embodiment is different from the switch device 10 of the second embodiment in that a third terminal 23 is added to the first terminal 21 and the second terminal 22, and the switch unit 300 is provided instead of the switch unit 200, and other components are the same. It should be noted that the third terminal 23 is an example of a second input terminal.

[0080] The switch device 10 of the present embodiment switches the first terminal 21 and the second terminal 22 from a connected state to a disconnected state, and switches the third terminal 23 and the second terminal 22 from a disconnected state to a connected state, or vice versa, switches the third terminal 23 and the second terminal 22 from a connected state to a disconnected state, and switches the first terminal 21 and the second terminal 22 from a disconnected state to a connected state, by connecting or disconnecting the first terminal 21 and the second terminal 22 and the third terminal 23 and the second terminal 22. Thus, the switch device 10 switches the alternating current flowing from the first terminal 21 to the second terminal 22 and the alternating current flowing from the third terminal 23 to the second terminal 22.

[0081] The switch unit 300 includes a mechanical switch unit 310, a first semiconductor switch unit 220, a second semiconductor switch unit 230, a diode bridge 240, a diode bridge 340, and a third semiconductor switch unit 330. The configuration of the mechanical switch unit 310 and the configuration and configuration of the first semiconductor switch unit 220, the second semiconductor switch unit 230, and the diode bridge 240 are the same as the corresponding components of the second embodiment.

[0082] The mechanical switch unit 310 is connected between the first terminal 21 and the second terminal 22 and between the third terminal 23 and the second terminal 22. The mechanical switch unit 310 is different from the mechanical switch unit 110 of the first embodiment and the like in that, like a double-headed mechanical switch, the state of connecting between the first terminal 21 and the first semiconductor switch unit 220 and the state of connecting between the third terminal 23 and the first semiconductor switch unit 220 are switched.

[0083] The first semiconductor switch unit 220 is connected in series with the mechanical switch unit 310 between the first terminal 21 and the third terminal 23 and the second terminal 22. The second semiconductor switch unit 230 is connected in parallel with the mechanical switch unit 310 and the first semiconductor switch unit 220 between the first terminal 21 and the second terminal 22.

[0084] The diode bridge 340 may be of the same configuration as the diode bridge 240, and is connected in parallel with the mechanical switch unit 310 and the first semiconductor switch unit 220 between the third terminal 23 and the second terminal 22. The diode bridge 340 includes a diode 341, a diode 342, a diode 343, and a diode 344, and a rectifying circuit is formed by performing full-wave rectification using the four diodes 341 and the like, so that an AC current flows in only one direction.

[0085] The third semiconductor switch unit 330 may be of the same configuration as the second semiconductor switch unit 230, connected in parallel with the mechanical switch unit 310 and the first semiconductor switch unit 220 between the third terminal 23 and the second terminal 22, and connected in parallel with the diode bridge 340 on the rectifier side of the diode bridge 340. The third semiconductor switch unit 330 includes a third semiconductor switch 331 and a capacitor 332 connected in parallel between the third terminal 23 and the second terminal 22. The third semiconductor switch 331 includes a group of semiconductor switch elements and diodes connected in reverse parallel between the third terminal 23 and the second terminal 22. As an example, the group of semiconductor switch elements and diodes includes an IGBT and a group of diodes connected in reverse parallel to the IGBT. The collector of the IGBT of the third semiconductor switch unit 330 is connected to the second terminal 22, the emitter is connected to the third terminal 23, and the gate is connected to the control circuit 40. The third semiconductor switch unit 330 may include a GTO thyristor, a WBG semiconductor, and the like.

[0086] Regarding the mechanical switch unit 310, when the first terminal 21 and the second terminal 22 are connected and the third terminal 23 and the second terminal 22 are disconnected, the control circuit 40 controls the mechanical switch unit 310 to connect the first terminal 21 and the first semiconductor switch unit 220, thereby allowing an alternating current to flow between the first terminal 21 and the second terminal 22. When the first terminal 21 and the second terminal 22 are disconnected and the third terminal 23 and the second terminal 22 are connected, the control circuit 40 controls the mechanical switch unit 310 to connect the third terminal 23 and the first semiconductor switch unit 220, thereby allowing an alternating current to flow between the third terminal 23 and the second terminal 22. When the mechanical switch unit 310 switches between these two states, the alternating current is switched from the first semiconductor switch unit 220 side to either the second semiconductor switch unit 230 side or the third semiconductor switch unit 330 side under the control of the control circuit 40. In the case of such control, no arc is generated in the mechanical switch unit 310. In addition, during the period when the second semiconductor switch unit 230 and the third semiconductor switch unit 330 are both in the on state, since the voltage between the corresponding first terminal 21 and the second terminal 22 or the voltage between the third terminal 23 and the second terminal 22 is only about several tens of V, instead of the above control, the mechanical switch unit 310 may be opened and closed before the above commutation is performed, thereby cutting off the current by the mechanical switch unit 310. In this case, the switch unit 300 may be additionally provided with a configuration for protecting the mechanical switch unit 310 from the arc generated in the mechanical switch unit 310.

[0087] Figure 5 It is a timing chart showing the operation of the switch unit 300 according to the third embodiment. Figure 5 The passage of time is shown horizontally, and vertically, in order from the top, the current on the second semiconductor switch unit 230 side, the current on the third semiconductor switch unit 330 side, the current on the first semiconductor switch unit 220 side, the on / off state of the second semiconductor switch unit 230, the on / off state of the third semiconductor switch unit 330, the open / closed state of the mechanical switch unit 310, and the time transition of the on / off state of the first semiconductor switch unit 220 are shown. In addition, Figure 5 The passage of time is mainly divided into three periods: period (I), period (II), and period (III) from the left.

[0088] Period (I) is a period during which, in the switch section 300, the mechanical switch section 310 is switched from a state of connecting the first terminal 21 and the first semiconductor switch section 220 to a state of connecting the third terminal 23 and the first semiconductor switch section 220, thereby switching the first terminal 21 and the second terminal 22 from a connected state to a disconnected state, and switching the third terminal 23 and the second terminal 22 from a disconnected state to a connected state. Period (II) is a period during which the alternating current is stably conducted between the third terminal 23 and the second terminal 22 in the switch section 300. Period (III) is a period during which, in the switch section 300, the mechanical switch section 310 is switched from a state of connecting the third terminal 23 and the first semiconductor switch section 220 to a state of connecting the first terminal 21 and the first semiconductor switch section 220, thereby switching the first terminal 21 and the second terminal 22 from a disconnected state to a connected state, and switching the third terminal 23 and the second terminal 22 from a connected state to a disconnected state.

[0089] It should be noted that Figure 5 In the timing shown, the period before period (I) and the period after period (III) are the periods in which the alternating current is stably conducted between the first terminal 21 and the second terminal 22 in the switching unit 300, and the period not shown can arbitrarily include period (I), period (II) and period (III).

[0090] In the stage before entering the period (I), the first semiconductor switch unit 220 and the second semiconductor switch unit 230 are in the on state, and the mechanical switch unit 310 is in the state of connecting the first terminal 21 and the first semiconductor switch unit 220. At the time t1 at the beginning of the period (I), the control circuit 40 is used to control the gate voltage of the low withstand voltage MOSFET of the first semiconductor switch unit 220, and the first semiconductor switch unit 220 is turned off. Since the switching speed of the low withstand voltage MOSFET is several tens of ns, it can be quickly turned off. By turning off the first semiconductor switch unit 220, the first semiconductor switch unit 220 side is completely cut off, and the AC current flowing through the first semiconductor switch unit 220 side is commutated to the second semiconductor switch unit 230 side. By keeping the mechanical switch unit 310 and the second semiconductor switch unit 230 in the on state and turning off the first semiconductor switch unit 220, a low-voltage MOSFET can still be used in the first semiconductor switch unit 220 because the AC voltage applied to the first semiconductor switch unit 220 is the on-state voltage of the IGBT of the second semiconductor switch unit 230, which is only a few V to tens of V.

[0091] The next moment t2 of period (I) has a time difference Δt1 relative to the moment t1. The time difference Δt1 only needs to be ensured to be the time required for the low-voltage MOSFET of the first semiconductor switch unit 220 to turn off, that is, it only needs to be ensured to be the time until the turn-off action is completed and the AC current flowing on the first semiconductor switch unit 220 side is commutated to the second semiconductor switch unit 230 side. As an example, the time difference Δt1 is about 1μ second to 2μ second. At the moment t2, the mechanical switch unit 310 is switched to a state of connecting the third terminal 23 and the first semiconductor switch unit 220 by using the control circuit 40. At this time, because the AC current has long stopped flowing on the first semiconductor switch unit 220 side, no arc is generated in the mechanical switch unit 310.

[0092] At the next time t3 of the period (I), the gate voltages of the IGBTs of the second semiconductor switch section 230 and the IGBTs of the third semiconductor switch section 330 are controlled by the control circuit 40, so that the second semiconductor switch section 230 is turned off and the third semiconductor switch section 330 is turned on, thereby completely cutting off the AC current flowing between the first terminal 21 and the second terminal 22 and making the AC current conduct between the third terminal 23 and the second terminal 22. Since the IGBTs of the second semiconductor switch section 230 and the third semiconductor switch section 330 are semiconductor switch elements capable of relatively high-speed switching operations, they can be turned on or off quickly, and when an overcurrent occurs in one system, the overall turning-off operation of the switch device 10 and the turning-on operation of the other system can be accelerated. That is, it is possible to switch from the abnormal system to the normal system on the other side at a high speed. In addition, if an accident occurs in the system passing through the first terminal 21 and there is a time period when both the second semiconductor switch unit 230 and the third semiconductor switch unit 330 are in the on state, although the accident current flows from the first terminal 21 through the second semiconductor switch unit 230 and the third semiconductor switch unit 330, the switch device 10 can prevent the accident current from flowing arbitrarily through the above-mentioned control.

[0093] The time t4 at the beginning of period (II) is delayed by a time td relative to the time t3 of period (I). on . Delay time td on The delay time td may be a time required for the IGBT of the third semiconductor switch unit 330 to be turned on, that is, a time until the turn-on operation is completed and a steady-state DC current flows through the IGBT of the third semiconductor switch unit 330. onIt is about 1μ second to 2μ second. At time t4, the control circuit 40 is used to control the gate voltage of the low withstand voltage MOSFET of the first semiconductor switch unit 220, and the first semiconductor switch unit 220 is turned on. Because the sum of the on-voltage of the mechanical switch unit 310 and the first semiconductor switch unit 220 is lower than the on-voltage of the third semiconductor switch unit 330, at time t4, the AC current flowing through the third semiconductor switch unit 330 side is commutated to the first semiconductor switch unit 220 side, and the AC current hardly flows to the third semiconductor switch unit 330 side. It should be noted that since the high voltage of the system is applied to the first semiconductor switch 221 of the first semiconductor switch unit 220 via the third terminal 23 at least from time t2 to time t3, the first semiconductor switch 221 is preferably a semiconductor switch element with high withstand voltage and capable of high-speed switching.

[0094] During the period (III), the switch device 10 performs control opposite to the above control performed during the period (I). In the stage before entering the period (III), the first semiconductor switch unit 220 and the third semiconductor switch unit 330 are in the on state, and the mechanical switch unit 310 is in the state of connecting the third terminal 23 and the first semiconductor switch unit 220. At the time t5 at the beginning of the period (III), the gate voltage of the low withstand voltage MOSFET of the first semiconductor switch unit 220 is controlled by the control circuit 40, and the first semiconductor switch unit 220 is turned off. By turning off the first semiconductor switch unit 220, the first semiconductor switch unit 220 side is completely cut off, and the AC current flowing through the first semiconductor switch unit 220 side is commutated to the third semiconductor switch unit 330 side. By keeping the mechanical switch unit 310 and the third semiconductor switch unit 330 in the on state and turning off the first semiconductor switch unit 220, the low-voltage MOSFET can still be used in the first semiconductor switch unit 220 because the AC voltage applied to the first semiconductor switch unit 220 is the on-state voltage of the IGBT of the third semiconductor switch unit 330 and is only about tens of V.

[0095] The next moment t6 of period (III) has a time difference Δt1 relative to the moment t1. The time difference Δt1 only needs to be ensured to be the time required for the low withstand voltage MOSFET of the first semiconductor switch unit 220 to turn off, that is, it only needs to be ensured to be the time until the turn-off action is completed and the AC current flowing through the first semiconductor switch unit 220 side is commutated to the third semiconductor switch unit 330 side. At the moment t6, the mechanical switch unit 310 is switched to a state of connecting the first terminal 21 and the first semiconductor switch unit 220 by using the control circuit 40 to open and close the mechanical switch unit 310. At this time, because the AC current has long stopped flowing on the first semiconductor switch unit 220 side, no arc is generated in the mechanical switch unit 310.

[0096] At the next moment t7 of period (III), the control circuit 40 is used to control the gate voltages of the IGBT of the third semiconductor switch unit 330 and the IGBT of the second semiconductor switch unit 230, thereby turning off the third semiconductor switch unit 330 and turning on the second semiconductor switch unit 230. This completely cuts off the AC current flowing between the third terminal 23 and the second terminal 22, and allows the AC current to flow between the first terminal 21 and the second terminal 22.

[0097] The next time t8 of period (III) is delayed by time td relative to time t7. off . Delay time td off The delay time td may be a time required for the IGBT of the second semiconductor switch unit 230 to be turned on, that is, a time until the turn-on operation is completed and a steady-state DC current flows through the IGBT of the second semiconductor switch unit 230. off It is about 1μ second to 2μ second. At time t8, the control circuit 40 is used to control the gate voltage of the low withstand voltage MOSFET of the first semiconductor switch unit 220, and the first semiconductor switch unit 220 is turned on. Because the sum of the on-voltage of the mechanical switch unit 310 and the first semiconductor switch unit 220 is lower than the on-voltage of the second semiconductor switch unit 230, at time t8, the AC current flowing through the second semiconductor switch unit 230 side is commutated to the first semiconductor switch unit 220 side, and the AC current hardly flows to the second semiconductor switch unit 230 side.

[0098] According to the switch device 10 of the third embodiment described above, the same effects as the switch devices 10 of the first and second embodiments are achieved. In addition, according to the switch device 10, the mechanical switch unit 310 and the first semiconductor switch unit 220 connected in series can be shared on the first terminal 21 side and the third terminal 23 side, and can be miniaturized and cost-effective. In addition, according to the switch device 10, when connected to a plurality of different systems, not only can the overall shut-off action of the switch device 10 and the conduction action of the system on the other side be accelerated when an overcurrent occurs in the system on one side, but also the accident current can be prevented from arbitrarily flowing from the system on one side to the system on the other side.

[0099] In the third embodiment, there may be no difference between time t2 and time t3, or time t2 and time t3 may be reversed. In addition, during the period from time t2 to time t3 and time t4, the mechanical switch unit 310 may be in a state where neither the first terminal 21 nor the third terminal 23 is connected to the first semiconductor switch unit 220. More specifically, by controlling the control device 5 via the control circuit 40, when the first semiconductor switch unit 220 and the second semiconductor switch unit 230 are in a conductive state and the mechanical switch unit 310 is in a state of connecting the first terminal 21 and the first semiconductor switch unit 220, the first terminal 21 and the second terminal 22 are switched from a connected state to a disconnected state, and the third terminal 23 and the second terminal 22 are switched from a disconnected state to a connected state, the first semiconductor switch unit 220 is turned off, and then the mechanical switch unit 310 is switched to a state in which neither the first terminal 21 nor the third terminal 23 is connected to the first semiconductor switch unit 220, and then the second semiconductor switch unit 230 is turned off and the third semiconductor switch unit 330 is turned on, and then the mechanical switch unit 310 is switched to a state in which the third terminal 23 is connected to the first semiconductor switch unit 220, and then the first semiconductor switch unit 220 is turned on.

[0100] In the above case, the switch device 10 may also include a voltmeter for detecting the potential difference between the third terminal 23 connected to the third semiconductor switch unit 330 and the second terminal 22. After the third semiconductor switch unit 330 is turned on, the mechanical switch unit 310 is switched to a state of connecting the third terminal 23 and the first semiconductor switch unit 220 according to the condition that the potential difference between the third terminal 23 and the second terminal 22 is below the reference through the control of the control device 5 via the control circuit 40.

[0101] In the above embodiments, the second semiconductor switch unit 230 or the third semiconductor switch unit 330 includes an IGBT. However, in applications where a switching speed is higher than that of an IGBT and a withstand voltage is lower than that of an IGBT, a power MOSFET may be used instead of the IGBT. In this case, the power MOSFET may be connected so that current flows from the source to the drain, thereby reducing current conduction loss through so-called synchronous rectification.

[0102] In the second and third embodiments above, the second semiconductor switch unit 230 or the third semiconductor switch unit 330 includes an IGBT connected in reverse parallel to a diode. However, a reverse-blocking IGBT (RB-IGBT) may be used instead.

Claims

1. A switch device, characterized in that: To conduct or cut off the current between the input terminal and the output terminal, the switch device comprises: a mechanical switch section and a first semiconductor switch section connected in series between the input terminal and the output terminal; a second semiconductor switch unit connected in parallel with the mechanical switch unit and the first semiconductor switch unit between the input terminal and the output terminal; a switch control unit for controlling the timing of turning on and off the first semiconductor switch unit and the second semiconductor switch unit, and the timing of opening and closing the mechanical switch unit; and a current detection unit provided between the input terminal and the output terminal, The switch control unit has: a protection circuit that outputs a shutdown command when an overcurrent is detected based on a signal from the current detection unit; a pulse distribution circuit that opens and closes the mechanical switch section based on a signal from the outside and outputs a pulse signal that is preset to turn on and off the first semiconductor switch section and the second semiconductor switch section, respectively, and closes the mechanical switch section and outputs a pulse signal that is preset to turn off the first semiconductor switch section and the second semiconductor switch section, respectively, regardless of the signal from the outside when the shutdown command is received from the protection circuit; as well as A drive circuit outputs a signal for opening and closing the mechanical switch section and a gate voltage for turning on and off the first semiconductor switch section and the second semiconductor switch section, respectively, based on the pulse signal received from the pulse distribution circuit.

2. The switch device according to claim 1, characterized in that: The withstand voltage of the first semiconductor switch portion is higher than the on-voltage of the second semiconductor switch portion.

3. The switch device according to claim 2, characterized in that: The first semiconductor switch unit includes a plurality of first semiconductor switches connected in parallel between the input terminal and the output terminal, and the second semiconductor switch unit includes a plurality of second semiconductor switches connected in series between the input terminal and the output terminal. The withstand voltage of each of the plurality of first semiconductor switches is higher than the sum of the on-state voltages of the plurality of second semiconductor switches.

4. The switch device according to any one of claims 1 to 3, characterized in that: When the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit are all in an on state, when the input terminal and the output terminal are switched from a connected state to a disconnected state, the switch control unit shuts down the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit in that order.

5. The switch device according to claim 4, characterized in that: When the input terminal and the output terminal are switched from a connected state to a disconnected state, the switch control unit turns off the mechanical switch unit after turning off the first semiconductor switch unit and then turns off the current of the first semiconductor switch unit to a value below a predetermined value.

6. The switch device according to any one of claims 1 to 3, characterized in that: When the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit are all in the off state, when the input terminal and the output terminal are switched from the disconnected state to the connected state, the switch control unit turns on the second semiconductor switch unit, the mechanical switch unit, and the first semiconductor switch unit in that order.

7. The switch device according to claim 4, characterized in that: When the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit are all in the off state, when the input terminal and the output terminal are switched from the disconnected state to the connected state, the switch control unit turns on the second semiconductor switch unit, the mechanical switch unit, and the first semiconductor switch unit in that order.

8. The switch device according to claim 5, characterized in that: When the first semiconductor switch unit, the mechanical switch unit, and the second semiconductor switch unit are all in the off state, when the input terminal and the output terminal are switched from the disconnected state to the connected state, the switch control unit turns on the second semiconductor switch unit, the mechanical switch unit, and the first semiconductor switch unit in that order.

9. The switch device according to claim 6, characterized in that: After turning on the second semiconductor switch unit, the switch control unit turns on the mechanical switch unit when the potential difference between the input terminal and the output terminal becomes equal to or smaller than a reference.

10. The switch device according to claim 7, characterized in that: After turning on the second semiconductor switch unit, the switch control unit turns on the mechanical switch unit when the potential difference between the input terminal and the output terminal becomes equal to or smaller than a reference.

11. The switch device according to claim 8, characterized in that After turning on the second semiconductor switch unit, the switch control unit turns on the mechanical switch unit when the potential difference between the input terminal and the output terminal becomes equal to or smaller than a reference.

12. The switch device according to any one of claims 1 to 3, characterized in that: The first semiconductor switch unit includes a plurality of first semiconductor switches connected in reverse series between the input terminal and the output terminal, each of the plurality of first semiconductor switches including a group of a semiconductor switch element and a diode connected in reverse parallel between the input terminal and the output terminal. The switching device further includes a diode bridge connected in parallel with the second semiconductor switch unit between the input terminal and the output terminal.

13. The switch device according to any one of claims 1 to 3, characterized in that: The first semiconductor switch unit includes a MOSFET, and the second semiconductor switch unit includes at least any one of an IGBT, a GTO thyristor, and a WBG semiconductor.

14. A switch device, characterized in that: have: A mechanical switch for switching a connection state between the first input terminal and the output terminal, and a connection state between the second input terminal and the output terminal; a first semiconductor switch unit connected in series with the mechanical switch between the first input terminal and the output terminal and between the second input terminal and the output terminal; a second semiconductor switch unit connected in parallel with the mechanical switch and the first semiconductor switch unit between the first input terminal and the output terminal; a third semiconductor switch unit connected in parallel with the mechanical switch and the first semiconductor switch unit between the second input terminal and the output terminal; and The switch control unit controls the timing of turning on and off the first semiconductor switch unit, the second semiconductor switch unit, and the third semiconductor switch unit, and the timing of opening and closing the mechanical switch.

15. The switch device according to claim 14, characterized in that When the first semiconductor switch unit and the second semiconductor switch unit are in the on state and the mechanical switching switch is in the state of connecting the first input terminal and the first semiconductor switch unit, when the first input terminal and the output terminal are switched from the connected state to the disconnected state and the second input terminal and the output terminal are switched from the disconnected state to the connected state, the switch control unit turns off the first semiconductor switch unit, then switches the mechanical switching switch to the state of connecting the second input terminal and the first semiconductor switch unit, then turns off the second semiconductor switch unit and turns on the third semiconductor switch unit, and then turns on the first semiconductor switch unit.

16. The switch device according to claim 14, characterized in that When the first semiconductor switch unit and the second semiconductor switch unit are in the on state and the mechanical switching switch is in the state of connecting the first input terminal and the first semiconductor switch unit, when the first input terminal and the output terminal are switched from the connected state to the disconnected state and the second input terminal and the output terminal are switched from the disconnected state to the connected state, the switch control unit turns off the first semiconductor switch unit, then switches the mechanical switching switch to a state in which neither the first input terminal nor the second input terminal is connected to the first semiconductor switch unit, then turns off the second semiconductor switch unit and turns on the third semiconductor switch unit, then switches the mechanical switching switch to a state in which the second input terminal is connected to the first semiconductor switch unit, and then turns on the first semiconductor switch unit.

17. The switch device according to claim 16, characterized in that After turning on the third semiconductor switch unit, the switch control unit switches the mechanical switch to a state connecting the second input terminal and the first semiconductor switch unit when the potential difference between the second input terminal and the output terminal becomes equal to or smaller than a reference.

18. The switch device according to any one of claims 14 to 17, characterized in that: The first semiconductor switch unit includes a plurality of first semiconductor switches connected in reverse series between the first input terminal and the output terminal, each of the plurality of first semiconductor switches including a group of a semiconductor switch element and a diode connected in reverse parallel between the first input terminal and the output terminal. The switch device also has: a first diode bridge connected in parallel with the second semiconductor switch portion between the first input terminal and the output terminal; and A second diode bridge is connected in parallel with the third semiconductor switch unit between the second input terminal and the output terminal.

19. The switch device according to any one of claims 14 to 17, characterized in that: The first semiconductor switch section includes a MOSFET, and at least any one of the second semiconductor switch section and the third semiconductor switch section includes at least any one of an IGBT, a GTO thyristor, and a WBG semiconductor.

20. The switch device according to claim 18, characterized in that The first semiconductor switch section includes a MOSFET, and at least any one of the second semiconductor switch section and the third semiconductor switch section includes at least any one of an IGBT, a GTO thyristor, and a WBG semiconductor.

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