Switch device

Abstract

To provide a switch device capable of suppressing occurence of failure on a switch element.SOLUTION: A switch device 1 includes: a first semiconductor switch 10 provides between a first terminal T1 and a second terminal T2; an electromagnetic relay 40 connected to the first semiconductor switch 10 in series; a second semiconductor switch 20 connected to the first semiconductor switch 10 and the electromagnetic relay 40 in parallel; and a protection circuit 60 electrically connected to the first semiconductor switch 10 through a first rectifying element 31 and a second rectifying element 32. The first rectifying element 31 has an anode connected to one end of the first semiconductor switch 10 and a cathode connected to the protection circuit 60. The second rectifying element 32 has an anode connected to the other end of the first semiconductor switch 10 and a cathode connected to the protection circuit 60. The protection circuit 60 drives the second semiconductor switch 20 when a voltage equal to or more than a first threshold value th1 is applied to the first semiconductor switch 10.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a switching device for controlling a load. [Background technology]

[0002] Conventionally, devices for controlling a load have been known. As an example of this type of device, Patent Document 1 discloses a device including a semiconductor switch provided in a power supply path connecting a power source and a load, and an electromagnetic relay provided between the semiconductor switch and the load in the power supply path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-77447 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, if power is applied to a switch device with the contacts of an electromagnetic relay erroneously closed, a high voltage may be applied to a switch element such as a field effect transistor, causing a malfunction of the switch element.

[0005] The present invention provides a switch device capable of suppressing malfunctions in a switch element. [Means for solving the problem]

[0006] One aspect of a switch device of the present invention includes a first terminal and a second terminal provided in a power supply path connecting an AC power source and a load, a first semiconductor switch provided in the power supply path between the first terminal and the second terminal, an electromagnetic relay provided in the power supply path between the first terminal and the second terminal and connected in series to the first semiconductor switch, a second semiconductor switch connected in parallel to the first semiconductor switch and the electromagnetic relay, and a protection circuit electrically connected to the first semiconductor switch via a first rectifier element and a second rectifier element, wherein the first rectifier element has an anode connected to one end of the first semiconductor switch and a cathode connected to the protection circuit, and the second rectifier element has an anode connected to the other end of the first semiconductor switch and a cathode connected to the protection circuit, and the protection circuit drives the second semiconductor switch when a voltage equal to or greater than a first threshold is applied to the first semiconductor switch. Effect of the Invention

[0007] The switch device of the present invention can suppress the occurrence of malfunctions in the switch elements. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is a circuit diagram of a switch device and a load control system of a comparative example. [Diagram 2] 6 is a timing chart showing an operation of a switch device of a comparative example when the switch device is powered on. [Diagram 3] 1 is a circuit diagram of a switch device and a load control system according to an embodiment. [Figure 4] 4 is a timing chart showing an operation during normal operation of the switch device according to the embodiment. [Diagram 5] 5 is a timing chart showing an operation of the switch device according to the embodiment when the switch device is turned on. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Background to the Invention) The process leading to the present invention will be described with reference to comparative examples. Note that the comparative examples shown here are examples presented to facilitate understanding of the present invention and are not publicly known techniques.

[0010] FIG. 1 is a circuit diagram of a switch device 1Z and a load control system 2Z of a comparative example.

[0011] 1, a load control system 2Z of the comparative example includes an AC power source AC, a load L, and a switch device 1Z. The switch device 1Z is provided in a power supply path SL that connects the AC power source AC and the load L. The load L is, for example, a lighting device such as a ceiling light or a downlight.

[0012] The switch device 1Z includes a first semiconductor switch 10 such as a field effect transistor, a second semiconductor switch 20 such as a thyristor, an electromagnetic relay 40, a power supply circuit section 30, a voltage detection section 58, a control section 50, and the like.

[0013] In the switch device 1Z, a high voltage is applied across the first semiconductor switch 10 due to various reasons. For example, when the contacts of the electromagnetic relay 40 malfunction due to vibration or impact caused by opening or closing a door, a high voltage is applied across the first semiconductor switch 10.

[0014] In response to this, the switch device 1Z is configured to place the second semiconductor switch 20 in a conductive state when a high voltage is applied to the first semiconductor switch 10, and further to open the contacts of the electromagnetic relay 40, thereby preventing an overvoltage from being applied to the first semiconductor switch 10.

[0015] FIG. 2 is a timing chart showing the operation of the switch device 1Z of the comparative example when the switch device 1Z is powered on.

[0016] In the figure, the open / closed state of the contacts of the electromagnetic relay 40, the voltage across the first semiconductor switch 10, the drive voltage for driving the control unit 50, and the voltage detected by the voltage detection unit 58 are shown.

[0017] For example, in electromagnetic relay 40, external vibrations such as opening and closing a door may move the movable piece that opens and closes the contacts, causing the contacts to erroneously become closed (see FIG. 2(a)). For example, if a high voltage is applied across first semiconductor switch 10 with the contacts of electromagnetic relay 40 in a closed state, during normal operation, the voltage detection unit 58 detects the voltage and places second semiconductor switch 20 in a conductive state, thereby preventing overvoltage from being applied to first semiconductor switch 10.

[0018] However, in this switch device 1Z, when the load control system 2Z is ​​powered on, there are cases where the control unit 50 and the like cannot be driven immediately. For example, the power supply circuit unit 30 of the switch device 1Z generates a drive voltage for driving the control unit 50 using an AC power supply AC, but the power supply circuit unit 30 has a capacitance element such as an electrolytic capacitor, and it takes several tens of ms to ensure a drive voltage of 3.3 V. Therefore, the drive voltage cannot be ensured for several tens of ms after the power supply is turned on (see (c) of FIG. 2), and the voltage cannot be detected using the voltage detection unit 58 (see (d) of FIG. 2). In addition, in the switch device 1Z, the second semiconductor switch 20 and the electromagnetic relay 40 cannot be controlled using the control unit 50 for several tens of ms after the power supply is turned on.

[0019] In this way, if the contacts of the electromagnetic relay 40 are erroneously closed when power is applied, in the switch device 1Z of the comparative example, an overvoltage is applied across the first semiconductor switch 10, which may cause a malfunction in the first semiconductor switch 10 (see FIG. 2(b)). The switch device of the present invention has the following configuration to prevent a malfunction in the semiconductor switch even if the contacts of the electromagnetic relay are erroneously closed when power is applied.

[0020] Hereinafter, the embodiments will be described with reference to the drawings. Note that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims showing the highest concept of the present invention will be described as optional components.

[0021] In addition, each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, the same reference numerals are used for substantially the same configuration, and duplicated explanations are omitted or simplified.

[0022] (Embodiment) The switch device according to the embodiment will be described with reference to FIGS.

[0023] FIG. 3 is a circuit diagram of the switch device 1 and the load control system 2 according to the embodiment.

[0024] As shown in FIG. 3, the load control system 2 includes an AC power source AC, a load L, and a switch device 1.

[0025] The AC power source AC is, for example, a commercial power source of 100V AC or 200V AC. The AC power source AC outputs a sinusoidal AC current (or AC voltage) having a constant period. Fig. 3 shows a single-phase two-wire power supply path SL connecting the AC power source AC and a load L. Note that the power supply path SL is provided with a breaker (not shown) for turning on and off the power supply to the load control system 2.

[0026] The load L is, for example, a lighting device or an air conditioning device. The load L is installed, for example, on a ceiling, which is an example of a building construction material. Although one load L is shown in the figure, the present invention is not limited to this, and the load L may be composed of a plurality of devices connected in parallel to each other. The operation of the load L is controlled by the AC waveform of the AC power source AC and the switch device 1.

[0027] The switch device 1 switches between supplying and not supplying power output from an AC power source AC, thereby controlling the operation of a load L. The switch device 1 is installed, for example, on a wall, which is an example of a construction material of a building.

[0028] As shown in FIG. 3, the switch device 1 includes a first terminal T1, a second terminal T2, a first semiconductor switch 10, a second semiconductor switch 20, an electromagnetic relay 40, a power supply circuit unit 30, a control unit 50, and a voltage detection unit 58.

[0029] The first terminal T1 and the second terminal T2 are provided on a power supply path SL that connects an AC power source AC and a load L. In this example, the first terminal T1 is located closer to the AC power source AC than the second terminal T2, and the second terminal T2 is located closer to the load L than the first terminal T1. In other words, the first terminal T1 is located closer to the AC power source AC than the first semiconductor switch 10, and the second terminal T2 is located closer to the load L than the first semiconductor switch 10.

[0030] The first semiconductor switch 10 is provided between a first terminal T1 and a second terminal T2 in a power supply path SL. The first semiconductor switch 10 is composed of two field effect transistors 11 and 12 connected in series to each other. The field effect transistors are, for example, N-type MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

[0031] Of the two field effect transistors, one field effect transistor 11 has a gate connected to the control unit 50, a drain connected to the first terminal T1, and a source connected to the source of the other field effect transistor 12. The other field effect transistor 12 has a gate connected to the control unit 50, a drain connected to the electromagnetic relay 40, and a source connected to the source of the one field effect transistor 11.

[0032] The first semiconductor switch 10 switches between a conductive state and a non-conductive state in response to a first gate signal s1 output from the control unit 50. For example, the field effect transistors 11 and 12 of the first semiconductor switch 10 are instantly turned on by an ON command of the first gate signal s1, and are instantly turned off by an OFF command of the first gate signal s1. After being turned off, the first semiconductor switch 10 maintains the non-conductive state until the next ON command is received.

[0033] The electromagnetic relay 40 is provided between the first semiconductor switch 10 and the second terminal T2 in the power supply path SL, and is connected in series to the first semiconductor switch 10. The electromagnetic relay 40 is, for example, a contact relay that switches between open and closed contacts by a pulse signal output from the control unit 50. The electromagnetic relay 40 is, for example, a self-holding latching relay that can maintain a closed or open state after switching. By using a latching relay as the electromagnetic relay 40, it is possible to reduce power consumption compared to using a self-resetting relay. In addition, in this switch device 1, since the electromagnetic relay 40 is connected in series to the first semiconductor switch 10, it is possible to lower the voltage applied to the first semiconductor switch 10 and to employ low-voltage field effect transistors 11 and 12 as the first semiconductor switch 10.

[0034] The second semiconductor switch 20 is a semiconductor element that has a higher withstand voltage and is capable of passing a large current than the first semiconductor switch 10. The second semiconductor switch 20 is connected in parallel to the first semiconductor switch 10 and the electromagnetic relay 40. Specifically, one end of the second semiconductor switch 20 is connected to a node n1 between the first terminal T1 and the first semiconductor switch 10, and the other end of the second semiconductor switch 20 is connected to a node n2 between the electromagnetic relay 40 and the second terminal T2. In this example, the first terminal T1 and the node n1 are at the same potential, and the second terminal T2 and the node n2 are at the same potential.

[0035] The second semiconductor switch 20 is a silicon controlled rectifier (SCR) such as a thyristor or a bidirectional thyristor (e.g., a triac). The second semiconductor switch 20 switches between a conductive state and a non-conductive state based on the second gate signal s2 output from the control unit 50 and the current flowing through the second semiconductor switch 20 itself. For example, the second semiconductor switch 20 becomes conductive by receiving an ON command of the second gate signal s2. On the other hand, when the second semiconductor switch 20 receives the release of the ON command of the second gate signal s2, the second semiconductor switch 20 does not immediately become non-conductive but maintains the conductive state while a current flows through it, and becomes non-conductive when the current flowing through it becomes equal to or less than a certain value (e.g., zero). After becoming non-conductive, the second semiconductor switch 20 maintains the non-conductive state until the next ON command is received.

[0036] The power supply circuit unit 30 is a circuit that generates a drive voltage (control voltage) for driving the control unit 50. The power supply circuit unit 30 is electrically connected to a first terminal T1 (or node n1) via a first rectifier element 31, and is electrically connected to a node n1a via a second rectifier element 32. Specifically, the anode of the first rectifier element 31 is connected to the first terminal T1 (or node n1), and the cathode is connected to the power supply circuit unit 30 via a node n3 located between the first rectifier element 31 and the power supply circuit unit 30. The anode of the second rectifier element 32 is connected to the node n1a, and the cathode is connected to the power supply circuit unit 30 via the node n3.

[0037] The power supply circuit unit 30 may be connected to a second terminal T2 (or node n2) in addition to the node n1a. That is, the power supply circuit unit 30 may be connected to the first terminal T1 via the first rectifying element 31, and to the node n1a via the second rectifying element 32, and may also be connected to the second terminal T2 (or node n2) via another rectifying element different from the second rectifying element 32.

[0038] The power supply circuit unit 30 obtains power from the first terminal T1 and the node n1a (or the second terminal T2) using the AC power supply AC as a power source. The power supply circuit unit 30 converts the obtained power into a predetermined DC voltage and outputs it to the control unit 50 as a drive voltage. The power supply circuit unit 30 of this embodiment generates a drive voltage using the AC power supply AC, but has a capacitive element such as an electrolytic capacitor, and requires several tens of ms (for example, 40 ms to 70 ms) to ensure a drive voltage of 3.3 V.

[0039] 3, the control unit 50 is composed of a first gate circuit 51, a second gate circuit 52, and an MCU (Micro Controller Unit) 55. Each of the first gate circuit 51 and the second gate circuit 52 is composed of a logic circuit.

[0040] The first gate circuit 51 is connected to the gate of the first semiconductor switch 10. Specifically, the first gate circuit 51 is connected to the gate of one field effect transistor 11 and the gate of the other field effect transistor 12. The first gate circuit 51 outputs a first gate signal s1 to the gates of the two field effect transistors 11 and 12, thereby switching the first semiconductor switch 10 between conductive and non-conductive states.

[0041] The second gate circuit 52 is connected to the gate of the second semiconductor switch 20. The second gate circuit 52 outputs a second gate signal s2 to the gate of the second semiconductor switch 20, thereby providing an on command and a release of the on command to the second semiconductor switch 20.

[0042] The MCU 55 uses the first gate circuit 51 and the second gate circuit 52 to control switching of the first semiconductor switch 10 between conductive and non-conductive states and switching of the output of an ON command and a release of the ON command to the second semiconductor switch 20 at every predetermined period. The predetermined period is, for example, half the period appearing in the AC waveform of the AC power source AC. Note that the predetermined period may be the same as the period appearing in the AC waveform of the AC power source AC, or may be a multiple of the half period appearing in the AC waveform.

[0043] 4 is a timing chart showing the normal operation of the switch device 1. Note that the normal operation refers to the period from at least one second after power-on when periodic operation is performed based on the alternating current power source AC.

[0044] 2 shows a first gate signal s1 received by the first semiconductor switch 10, a second gate signal s2 received by the second semiconductor switch 20, the inter-terminal voltages between the first terminal T1 and the second terminal T2, and a load current supplied to the load L. A sinusoidal load current is supplied to the load L.

[0045] The figure also shows a timing chart regarding the completion of securing the drive voltage for driving the control unit 50. The power supply circuit unit 30 generates a drive voltage when the current of the AC power supply AC rises after crossing zero at time t=t0, but it takes a certain amount of time to generate the drive voltage. Therefore, when the power supply circuit unit 30 has generated a sufficient drive voltage, it outputs a drive voltage securing completion signal to the control unit 50, indicating that securing of the drive voltage has been completed.

[0046] The control unit 50 controls the semiconductor switch via the gate circuit by receiving the drive voltage securing completion signal. First, the control unit 50 controls the conduction and non-conduction of the first semiconductor switch 10 via the first gate circuit 51. The conduction time of the first semiconductor switch 10 is preset by a timer.

[0047] For example, the control unit 50 outputs an ON command and a release of the ON command to the second semiconductor switch 20 so as to straddle the falling edge from conductive to non-conductive (t=t2) after making the first semiconductor switch 10 conductive (t=t1). Specifically, before switching the first semiconductor switch 10 from conductive to non-conductive, the control unit 50 outputs an ON command to the second semiconductor switch 20 to make the second semiconductor switch 20 conductive. In addition, the control unit 50 outputs a release of the ON command to the second semiconductor switch 20 before the current of the AC power source AC becomes zero after switching the first semiconductor switch 10 to non-conductive.

[0048] The voltage detection unit 58 shown in FIG. 3 is a circuit that detects the voltage applied to the first semiconductor switch 10.

[0049] One end of the voltage detection unit 58 is connected to the node n1, and the other end is connected to a node n1a between the first semiconductor switch 10 and the electromagnetic relay 40. The voltage detection unit 58 is configured to detect the potential of either end of the first semiconductor switch 10 (node ​​n1 or n1a). Specifically, the voltage detection unit 58 is connected to the first terminal T1 (or node n1) via the first rectifier element 31, and detects the potential at the first terminal T1. The voltage detection unit 58 is also connected to the node n1a via the second rectifier element 32, and detects the potential at the node n1a.

[0050] The voltage detection unit 58 is connected to the second gate circuit 52 , and controls the operation of the second gate circuit 52 .

[0051] When the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, the voltage detection unit 58 activates the second gate circuit 52 and outputs an ON command to the second semiconductor switch 20. The predetermined voltage is set to a voltage lower than the withstand voltage of the first semiconductor switch 10. The threshold voltage detected by the voltage detection unit 58 is a second threshold th2, which will be described later. For example, when the withstand voltage (allowable voltage) of the first semiconductor switch 10 is 60V, the second threshold th2 is set to 25V.

[0052] 4, during normal operation, when the control unit 50 detects, using the voltage detection unit 58, that the voltage applied to the first semiconductor switch 10 is higher than the second threshold value th2, the control unit 50 outputs an ON command to the second semiconductor switch 20 to make the second semiconductor switch 20 conductive. Furthermore, when the voltage detected by the voltage detection unit 58 is equal to or higher than the second threshold value th2, the control unit 50 makes the electromagnetic relay 40, which is in a conductive state, non-conductive (cut-off) state.

[0053] As described above, in the electromagnetic relay 40, the movable piece that opens and closes the contacts may move due to external vibrations, such as when a door is opened and closed, causing the contacts to be erroneously closed. In addition, in the switch device 1, the drive voltage cannot be secured for several tens of milliseconds after the power is turned on, and the voltage cannot be detected using the voltage detection unit 58, or the second semiconductor switch 20 and the electromagnetic relay 40 cannot be controlled using the control unit 50.

[0054] The switch device 1 of the present embodiment is provided with a protection circuit 60 described below in order to prevent malfunction of the first semiconductor switch 10 even if the contacts of the electromagnetic relay 40 are erroneously closed when the power is turned on.

[0055] The protection circuit 60 is a circuit that drives the second semiconductor switch 20 when a voltage equal to or greater than a first threshold th1 is applied to the first semiconductor switch 10, thereby preventing an overvoltage from being applied to the first semiconductor switch 10.

[0056] The protection circuit 60 is electrically connected to the first semiconductor switch 10 via the first rectifying element 31 and the second rectifying element 32. In the example shown in Fig. 3, the first rectifying element 31 has an anode connected to one end of the first semiconductor switch 10 and a cathode connected to one end of the protection circuit 60. The second rectifying element 32 has an anode connected to the other end of the first semiconductor switch 10 and a cathode connected to one end of the protection circuit 60.

[0057] The protection circuit 60 includes a constant voltage diode 61 and a third rectifier element 63 connected in series to the constant voltage diode 61 .

[0058] The constant voltage diode 61 is, for example, a Zener diode. The above-mentioned first threshold th1 is the Zener voltage of the constant voltage diode 61. The first threshold th1 is a voltage value that triggers driving the second semiconductor switch 20, and is set to a value lower than the withstand voltage of the first semiconductor switch 10. The first threshold th1 is, for example, a voltage value that is 0.5 to 0.8 times the withstand voltage (allowable voltage) of the first semiconductor switch 10. In this example, the withstand voltage of the first semiconductor switch 10 is 60V, and the first threshold th1 of the constant voltage diode 61, i.e., the Zener voltage, is 35V.

[0059] The first threshold value th1 is set to a value larger than the second threshold value th2. The reason why the second threshold value th2 is set to a value smaller than the first threshold value th1 is that during normal operation, it is desirable to protect the first semiconductor switch 10 based on the second threshold value th2 and to manage the presence or absence of an abnormality in the switch device 1 using the control unit 50 including the voltage detection unit 58.

[0060] 3 is connected to a node n1 of the first semiconductor switch 10 via a node n3a located between the node n3 and the power supply circuit unit 30, the node n3, and the first rectifier element 31, and is also connected to a node n1a of the first semiconductor switch 10 via the node n3a, the node n3, and the second rectifier element 32. That is, the cathode of the constant voltage diode 61 is connected to one end and the other end, which are both ends of the first semiconductor switch 10. On the other hand, the anode of the constant voltage diode 61 is electrically connected to the second gate circuit 52 via the third rectifier element 63. The nodes n3 and n3a are at the same potential.

[0061] The third rectifier element 63 is an element for preventing a signal output from the second gate circuit 52 from being output to both ends of the first semiconductor switch 10 or to a circuit other than the first semiconductor switch 10, such as the voltage detection unit 58. The anode of the third rectifier element 63 is connected to the anode of the voltage constant diode 61, and the cathode of the third rectifier element 63 is directly connected to the second gate circuit 52. Note that the positions of the third rectifier element 63 and the voltage constant diode 61 may be reversed, and the third rectifier element 63 may be connected to the second gate circuit 52 via the voltage constant diode 61. That is, the anode of the third rectifier element 63 may be electrically connected to both ends of the first semiconductor switch 10, the cathode of the third rectifier element 63 may be connected to the cathode of the voltage constant diode 61, and the anode of the voltage constant diode 61 may be connected to the second gate circuit 52.

[0062] In this manner, the protection circuit 60 is disposed on a path connecting the first semiconductor switch 10 and the second gate circuit 52. The protection circuit 60 drives the second semiconductor switch 20 via the second gate circuit 52.

[0063] The second gate circuit 52 includes a phototriac, which is an example of a coupling element. The phototriac is composed of a light-emitting element connected to two input terminals and a light-receiving element connected to two output terminals. A signal voltage output from the protection circuit 60 is input to one of the two input terminals. A gate of the second semiconductor switch 20 to be driven is connected to one of the two output terminals. The two ends of the output side are connected to the first terminal T1 and the second terminal T2, respectively, via resistor elements. For example, when the voltage of one end or the other end of the first semiconductor switch 10 exceeds the first threshold th1, the signal voltage output from the protection circuit 60 is input to the second gate circuit 52, the phototriac is turned on based on this signal voltage, and an ON command signal is output to the gate of the second semiconductor switch 20.

[0064] This switch device 1 is configured such that, when the voltage applied to the first semiconductor switch 10 is higher than a first threshold value th1, the protection circuit 60 places the second semiconductor switch 20 in a conductive state.

[0065] FIG. 5 is a timing chart showing the operation of the switch device 1 when the switch device 1 is powered on.

[0066] The figure shows the open / closed state of the contacts of the electromagnetic relay 40, the voltage across the first semiconductor switch 10, the drive voltage for driving the control unit 50, the voltage detected by the voltage detection unit 58, the pulse signal for opening the contacts of the electromagnetic relay 40, the signal voltage output by the protection circuit 60, and the conductive state of the second semiconductor switch 20.

[0067] When power is turned on, the contacts of the electromagnetic relay 40 should be open so that AC voltage is not applied to the first semiconductor switch 10. However, if the contacts of the electromagnetic relay 40 are mistakenly closed, as shown in FIG. 5(a), the voltage across the first semiconductor switch 10 will rise rapidly, as shown in (b).

[0068] In contrast, in this example, when the voltage across the first semiconductor switch 10 becomes equal to or greater than the first threshold th1, the protection circuit 60 outputs a signal voltage as shown in FIG. 5(f), and the second semiconductor switch 20 becomes conductive as shown in FIG. 5(g). That is, the protection circuit 60 maintains the second semiconductor switch 20 in a conductive state before the drive voltage for driving the control unit 50 is secured and when the voltage applied to the first semiconductor switch 10 is higher than the first threshold th1. In this way, even if the contacts of the electromagnetic relay 40 are closed, for example, the second semiconductor switch 20 is brought into a conductive state, thereby preventing an overvoltage from being applied to the first semiconductor switch 10. This makes it possible to prevent malfunctions in the first semiconductor switch 10.

[0069] Furthermore, in the switch device 1, when the predetermined drive voltage of 3.3V has been secured after several tens of milliseconds (see FIG. 5(c)), the voltage applied to the first semiconductor switch 10 is detected by the voltage detection unit 58 (see FIG. 5(d)). If the voltage detected by the voltage detection unit 58 is equal to or greater than the second threshold value th2, the control unit 50 outputs a pulse signal for opening the contacts of the electromagnetic relay 40 (see FIG. 5(e)). As a result, the closed contacts of the electromagnetic relay 40 are opened (see FIG. 5(a)).

[0070] Furthermore, the control unit 50 notifies the outside of the abnormality occurrence information indicating that the contact of the electromagnetic relay 40 was closed when the power was turned on. For example, the control unit 50 may notify the outside of the abnormality occurrence information using an LED lamp, or may notify a communication terminal such as a smartphone via a wireless communication module. This makes it possible to notify the abnormality occurrence information in the switch device 1 and to manage the occurrence state of the abnormality.

[0071] (summary) The switch device of the present disclosure will be exemplified below.

[0072] The switch device 1 of Example 1 includes a first terminal T1 and a second terminal T2 provided in a power supply path SL connecting an AC power source AC and a load L, a first semiconductor switch 10 provided between the first terminal T1 and the second terminal T2 in the power supply path SL, an electromagnetic relay 40 provided between the first terminal T1 and the second terminal T2 in the power supply path SL and connected in series to the first semiconductor switch 10, a second semiconductor switch 20 connected in parallel to the first semiconductor switch 10 and the electromagnetic relay 40, and a protection circuit 60 electrically connected to the first semiconductor switch 10 via a first rectifier element 31 and a second rectifier element 32. The first rectifier element 31 has an anode connected to one end of the first semiconductor switch 10 and a cathode connected to the protection circuit 60. The second rectifier element 32 has an anode connected to the other end of the first semiconductor switch 10 and a cathode connected to the protection circuit 60. The protection circuit 60 drives the second semiconductor switch 20 when a voltage equal to or greater than a first threshold th1 is applied to the first semiconductor switch 10.

[0073] In this manner, by driving the second semiconductor switch 20 when a voltage equal to or greater than the first threshold th1 is applied to the first semiconductor switch 10, it is possible to prevent an overvoltage from being applied to the first semiconductor switch 10. This makes it possible to prevent a malfunction of the first semiconductor switch 10.

[0074] Furthermore, by connecting the first semiconductor switch 10 and the electromagnetic relay 40 in series, it is possible to employ the first semiconductor switch 10 with low voltage resistance as a component of the switch device 1. This makes it possible to reduce the on-resistance of the first semiconductor switch 10.

[0075] The switch device 1 of Example 2 may be the switch device described in Example 1, in which the protection circuit 60 includes a constant voltage diode 61 and a third rectifier element 63 connected in series to the constant voltage diode 61.

[0076] According to this, when a voltage equal to or greater than the first threshold th1 is applied to the constant voltage diode 61, the second semiconductor switch 20 can be driven. This makes it possible to prevent an overvoltage from being applied to the first semiconductor switch 10. This makes it possible to prevent a malfunction of the first semiconductor switch 10.

[0077] The switch device 1 of Example 3 is the switch device described in Example 2, in which the first semiconductor switch 10 is connected to a first gate circuit 51 that outputs a signal for switching the first semiconductor switch 10 between conductive and non-conductive states. The protection circuit 60 may be connected to a second gate circuit 52 that outputs an on command signal or an on command release signal to the second semiconductor switch 20, and drive the second semiconductor switch 20 via the second gate circuit 52.

[0078] In this manner, the protection circuit 60 drives the second semiconductor switch 20 via the second gate circuit 52, so that the second semiconductor switch 20 can be driven using the second gate circuit 52 that was originally provided for driving the second semiconductor switch 20. This makes it possible to suppress the occurrence of malfunctions in the first semiconductor switch 10 with a simple structure.

[0079] The switch device 1 of Example 4 is the switch device described in Example 3, in which the cathode of the constant voltage diode 61 is connected to one end of the first semiconductor switch 10 via the first rectifier element 31 and to the other end of the first semiconductor switch 10 via the second rectifier element 32. The anode of the constant voltage diode 61 may be electrically connected to the second gate circuit 52.

[0080] According to this, when a voltage equal to or greater than the first threshold th1 is applied to the constant voltage diode 61 via the first rectifier element 31 or the second rectifier element 32, the second semiconductor switch 20 can be driven. This makes it possible to prevent an overvoltage from being applied to the first semiconductor switch 10. This makes it possible to prevent a malfunction of the first semiconductor switch 10.

[0081] The switch device 1 of Example 5 is the switch device described in Example 4, and the cathode of the third rectifier element 63 may be directly connected to the second gate circuit 52 or may be connected to the second gate circuit 52 via a constant voltage diode 61.

[0082] This makes it possible to prevent, for example, a signal output from the control unit 50 to the second gate circuit 52 from being output to both ends of the first semiconductor switch 10 or to a voltage detection unit 58 or the like which is a circuit other than the first semiconductor switch 10. This makes it possible to prevent malfunctions from occurring in the first semiconductor switch 10 or circuits other than the first semiconductor switch 10.

[0083] The switch device 1 of Example 6 is the switch device described in any one of Examples 1 to 5, and may further include a control unit 50 that switches the first semiconductor switch 10 between conductive and non-conductive states, switches the output of an on command and a release of the on command to the second semiconductor switch 20, and switches the contacts of the electromagnetic relay 40 between open and closed states.

[0084] According to this, for example, during normal operation, by outputting an ON command to the second semiconductor switch 20 before switching the first semiconductor switch 10 from conductive to non-conductive, when the first semiconductor switch 10 becomes non-conductive, the current of the AC power source AC can be output to the load L side via the second semiconductor switch 20. Therefore, even when the first semiconductor switch 10 is turned off, a current is supplied to the load L, and the generation of a counter electromotive force by the load L can be suppressed. This makes it possible to suppress the occurrence of a malfunction in the first semiconductor switch 10.

[0085] The switch device 1 of Example 7 is the switch device described in Example 6, and the protection circuit 60 may maintain the second semiconductor switch 20 in a conductive state when the voltage applied to the first semiconductor switch 10 is higher than a first threshold value th1 before the drive voltage for driving the control unit 50 is secured.

[0086] In this manner, by maintaining the second semiconductor switch 20 in a conductive state when the voltage applied to the first semiconductor switch 10 is higher than the first threshold value th1, it is possible to prevent an overvoltage from being applied to the first semiconductor switch 10 even before a drive voltage for driving the control unit 50 is secured. This makes it possible to prevent a malfunction of the first semiconductor switch 10.

[0087] The switch device 1 of Example 8 may be the switch device according to Example 6 or 7, and further include a power supply circuit unit 30 that generates a drive voltage for driving the control unit 50.

[0088] This allows the control unit 50 to be stably driven and stably controls the first semiconductor switch 10 and the second semiconductor switch 20. This makes it possible to prevent malfunctions in the first semiconductor switch 10.

[0089] The switch device 1 of Example 9 is the switch device described in any one of Examples 6 to 8, and the control unit 50 may have a voltage detection unit 58 that detects a voltage applied to the first semiconductor switch 10, and when the detected voltage detected by the voltage detection unit 58 is a voltage equal to or greater than a second threshold value th2, the control unit 50 may bring the second semiconductor switch 20 into a conductive state and the electromagnetic relay 40 into a non-conductive state.

[0090] According to this, when the voltage applied to the first semiconductor switch 10 is equal to or higher than the second threshold th2, an ON command is output to the second semiconductor switch 20 to bring the second semiconductor switch 20 into a conductive state, thereby making it possible to prevent an overvoltage from being applied to the first semiconductor switch 10. This makes it possible to prevent a malfunction of the first semiconductor switch 10.

[0091] The switch device 1 of Example 10 may be the switch device according to Example 9, in which the first threshold th1 is set to a value higher than the second threshold th2.

[0092] According to this, during normal operation, the second semiconductor switch 20 is made conductive using the second threshold value th2, i.e., using the detection result of the voltage detection unit 58, thereby making it possible to protect the first semiconductor switch 10. Furthermore, when the power is turned on, the second semiconductor switch 20 is made conductive using the protection circuit 60 using the first threshold value th1, i.e., without using the voltage detection unit 58, thereby making it possible to protect the first semiconductor switch 10.

[0093] The switch device 1 of Example 11 may be the switch device according to any one of Examples 1 to 10, and the electromagnetic relay 40 may be a latching relay.

[0094] With this, even if, for example, the movable piece of the latching relay moves and the contacts are held in a closed state, the second semiconductor switch 20 is driven using the protection circuit 60, thereby preventing an overvoltage from being applied to the first semiconductor switch 10. This makes it possible to prevent malfunctions in the first semiconductor switch 10.

[0095] The switch device 1 of Example 12 is the switch device according to any one of Examples 1 to 11, in which the first semiconductor switch 10 is a switch including a field effect transistor, and the second semiconductor switch 20 may be a thyristor or a bidirectional thyristor.

[0096] The first semiconductor switch 10 can instantly switch between conductive and non-conductive states. The second semiconductor switch 20 is conductive when it receives an ON command, and does not immediately switch to a non-conductive state when it receives a release of the ON command, but maintains the conductive state while a current flows through it, and switches to a non-conductive state when the current flowing through it falls below a certain value. The second semiconductor switch 20 can suppress the generation of a counter electromotive force by the load L when the first semiconductor switch 10 is turned off.

[0097] (Other forms) Although the switch device has been described above based on the embodiment, the present invention is not limited to the above embodiment. For example, the present invention also includes forms obtained by applying various modifications to the above embodiment that a person skilled in the art can conceive, and forms realized by arbitrarily combining the components and functions of the embodiment within the scope of the gist of the present invention.

[0098] In the above, the electromagnetic relay 40 is disposed on the load L side as viewed from the first semiconductor switch 10, but this is not limiting. For example, the electromagnetic relay 40 may be disposed on the AC power source AC side as viewed from the first semiconductor switch 10. In other words, the electromagnetic relay 40 may be provided between the first semiconductor switch 10 and the first terminal T1 in the power supply path SL.

[0099] In the above, an example has been described in which the voltage detection unit 58 is included in the control unit 50, but this is not limiting. The voltage detection unit 58 may be provided outside the control unit 50 as a separate component different from the control unit 50. In this case, the drive voltage of the voltage detection unit 58 may be supplied from the power supply circuit unit 30. Furthermore, the voltage detection unit 58 may be provided outside the MCU 55 as a separate component different from the MCU 55, or the voltage detection unit 58 may be provided inside the MCU 55. In other words, the MCU 55 may have the function of the voltage detection unit 58.

[0100] In the above, an example in which the voltage detection unit 58 is connected to the second gate circuit 52 has been described, but the present invention is not limited to this. For example, each of the voltage detection unit 58 and the MCU 55 may be connected to the second gate circuit 52 and control the operation of the second gate circuit 52. In other words, the MCU 55 may control the operation of the load L by operating the first gate circuit 51 and the second gate circuit 52 and controlling the on and off of the first semiconductor switch 10 and the second semiconductor switch 20. [Explanation of symbols]

[0101] 1, 1Z Switching device 10 First semiconductor switch 11, 12 Field effect transistor 20 Second semiconductor switch 30 Power supply circuit section 31 First rectifier element 32 Second rectifier element 40 Electromagnetic Relay 50 Control section 51 First gate circuit 52 Second gate circuit 58 Voltage detection section 60 Protection circuit 61 Constant voltage diode 63 Third rectifier element AC alternating current power supply L load SL Power supply route T1 Terminal 1 T2 Second terminal th1 First threshold th2 Second threshold

Claims

1. a first terminal and a second terminal provided on a power supply path connecting an AC power source and a load; a first semiconductor switch provided in the power supply path between the first terminal and the second terminal; an electromagnetic relay provided in the power supply path between the first terminal and the second terminal and connected in series to the first semiconductor switch; a second semiconductor switch connected in parallel to the first semiconductor switch and the electromagnetic relay; a protection circuit electrically connected to the first semiconductor switch via a first rectifier element and a second rectifier element; Equipped with the first rectifying element has an anode connected to one end of the first semiconductor switch and a cathode connected to the protection circuit; the second rectifier element has an anode connected to the other end of the first semiconductor switch and a cathode connected to the protection circuit; The protection circuit drives the second semiconductor switch when a voltage equal to or greater than a first threshold is applied to the first semiconductor switch. Switch device.

2. The protection circuit includes a constant voltage diode and a third rectifier element connected in series to the constant voltage diode. The switch device according to claim 1 .

3. the first semiconductor switch is connected to a first gate circuit that outputs a signal for switching the first semiconductor switch between conductive and non-conductive states; The protection circuit is connected to a second gate circuit that outputs an ON command signal or an ON command release signal to the second semiconductor switch, and drives the second semiconductor switch via the second gate circuit. The switch device according to claim 2 .

4. a cathode of the constant voltage diode is connected to one end of a first semiconductor switch via the first rectifier element, and is connected to the other end of the first semiconductor switch via the second rectifier element; The anode of the constant voltage diode is electrically connected to the second gate circuit. The switch device according to claim 3.

5. The cathode of the third rectifier element is directly connected to the second gate circuit, or is connected to the second gate circuit via the constant voltage diode. The switch device according to claim 4.

6. The control unit further performs switching between conductive and non-conductive states of the first semiconductor switch, switching between output of an ON command and a release of the ON command for the second semiconductor switch, and switching between opening and closing of the contacts of the electromagnetic relay. The switch device according to any one of claims 1 to 5.

7. The protection circuit maintains the second semiconductor switch in a conductive state when a voltage applied to the first semiconductor switch is higher than the first threshold before a drive voltage for driving the control unit is secured. The switch device according to claim 6.

8. The control unit further includes a power supply circuit unit that generates a drive voltage for driving the control unit. The switch device according to claim 6.

9. The control unit has a voltage detection unit that detects a voltage applied to the first semiconductor switch, and when a detected voltage detected by the voltage detection unit is a voltage equal to or higher than a second threshold value, the control unit turns on the second semiconductor switch and turns on the electromagnetic relay. The switch device according to claim 6.

10. The first threshold is set to a value higher than the second threshold. The switch device according to claim 9.

11. The electromagnetic relay is a latching relay. The switch device according to any one of claims 1 to 5.

12. the first semiconductor switch is a switch including a field effect transistor, The second semiconductor switch is a thyristor or a bidirectional thyristor. The switch device according to any one of claims 1 to 5.

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