Switching device

Abstract

To provide a switch device capable of suppressing the generation of failure in a switch element.SOLUTION: A switch device 1 comprises: a first semiconductor switch 10 that is provided to a power supply path SL connecting an AC power supply AC and a load L; a second semiconductor switch 20 that is parallely connected to the first semiconductor switch 10; and a control part 50 that performs a switch of a conduction and a non-conduction of the first semiconductor switch 10 in a predetermined period and a switch of an on instruction again to the second semiconductor switch 20 and an output of a cancel of the on instruction. The control part 50 sets the second semiconductor switch 20 to be a conductive state by outputting the on instruction to the second semiconductor switch 20 before the first semiconductor switch 10 is switched from the conduction to the non-conduction, and the first semiconductor switch 10 is switched to the non-conduction, and the cancellation of the on instruction is output to the second semiconductor switch 20 before a current of the AC power supply becomes zero.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a switch device for controlling a load.

Background Art

[0002] Conventionally, devices for controlling loads such as lighting fixtures have been known. As an example of this type of device, Patent Document 1 discloses a dimming device including a first switch element provided between an AC power supply and a load, a second switch element connected in parallel with the first switch element, and a zero-cross detection circuit that detects the zero-cross of the waveform output from the AC power supply. In this dimming device, conduction and non-conduction of one of the two switch elements are controlled based on the timing of the zero-cross detected by the zero-cross detection circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the device disclosed in Patent Document 1, for example, a back electromotive force caused by the load may occur when the switch element is turned off, and a problem may occur in the switch element.

[0005] The present invention provides a switch device that can suppress problems from occurring in the switch element.

Means for Solving the Problems

[0006] One embodiment of the switch device of the present invention comprises: 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 between the first terminal and the second terminal in the power supply path; a second semiconductor switch connected in parallel to the first semiconductor switch; and a control unit that switches the conduction and non-conductivity of the first semiconductor switch, and outputs an ON command and a release of the ON command to the second semiconductor switch, at each half-cycle or multiplier of the half-cycle that appears in the AC waveform of the AC power source, wherein the control unit outputs an ON command to the second semiconductor switch to make the second semiconductor switch conduction before switching the first semiconductor switch from conduction to non-conductivity, and then switches the first semiconductor switch to non-conductivity before the AC power source The flow to the aforementioned load is caused by Before the current becomes zero, at the same timing during the half-cycle or multiplication of the half-cycle, an ON command cancellation is output to the second semiconductor switch. [Effects of the Invention]

[0007] The switch device of the present invention can suppress malfunctions in the switch element. [Brief explanation of the drawing]

[0008] [Figure 1] This is a circuit diagram of a comparative example switch device and load control system. [Figure 2] This is a timing chart showing the operation of the switch device in the comparative example. [Figure 3] This is a circuit diagram of a switch device and load control system according to Embodiment 1. [Figure 4] This is a timing chart showing the operation of the switch device according to Embodiment 1. [Figure 5] This is a circuit diagram of a switch device and load control system according to Embodiment 2. [Figure 6] This is a circuit diagram of a switch device and load control system according to a modified example of Embodiment 2. [Figure 7]This is a circuit diagram of a switch device and load control system according to Embodiment 3. [Figure 8] This is a circuit diagram of a switch device and load control system according to a modified example of Embodiment 3. [Modes for carrying out the invention]

[0009] (Background to the present invention) The background leading to the present invention will be explained with reference to comparative examples.

[0010] Figure 1 is a circuit diagram of a comparative example switch device 101 and load control system 102.

[0011] As shown in Figure 1, the comparative example load control system 102 comprises an AC power supply, a load L, and a switch device 101. The switch device 101 is installed in the power supply path SL that connects the AC power supply and the load L.

[0012] The load L is, for example, a lighting device such as a ceiling light or a downlight. The switching device 101 is composed of semiconductor switches 110 such as field-effect transistors.

[0013] Figure 2 is a timing chart showing the operation of the comparative example switch device 101.

[0014] The figure shows the switching between conduction and non-conductivity of the semiconductor switch 110, the inter-switch voltage which is the voltage across the semiconductor switch 110, and the load current supplied to the load L.

[0015] In the load control system 102, the control unit 150 generates a load current of a predetermined waveform by switching the conduction and non-conductivity of the semiconductor switch 110 at each half-cycle that appears in the AC waveform of the AC power supply, thereby controlling the operation of the load L.

[0016] For example, when the load L is an inductive device such as a lighting device, a back electromotive force is generated when the semiconductor switch 110 is turned off (t = t2). When a back electromotive force caused by the load L occurs, an overvoltage is applied to the semiconductor switch 110, which may have an adverse effect on the semiconductor switch 110.

[0017] The switch device of the present invention has the following configuration in order to suppress the generation of a back electromotive force caused by the load L when the semiconductor switch is turned off. Further, the switch device of the present invention has the following configuration in order to suppress a malfunction in the semiconductor switch due to the generated back electromotive force even when a back electromotive force caused by the load L occurs.

[0018] Hereinafter, 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, numerical values, shapes, materials, components, arrangement positions of components, connection forms, etc. 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 not described in the independent claims indicating the most general concept of the present invention are described as arbitrary components.

[0019] Each figure is a schematic diagram and is not necessarily drawn precisely. Also, in each figure, the same reference numerals are assigned to substantially the same configurations, and duplicate explanations are omitted or simplified.

[0020] (Embodiment 1) The switch device according to Embodiment 1 will be described with reference to FIGS. 3 and 4.

[0021] FIG. 3 is a circuit diagram of the switch device 1 and the load control system 2 according to Embodiment 1.

[0022] As shown in FIG. 3, the load control system 2 includes an AC power supply AC, a load L, and a switch device 1.

[0023] AC power is, for example, a commercial power supply of 100V or 200V AC. AC power outputs a sinusoidal alternating current (or AC voltage) with a constant period. Figure 3 shows a single-phase two-wire power supply path SL connecting the AC power supply and the load L.

[0024] The load L is, for example, a lighting device or an air conditioning device. The load control system 2 has an inductive component that exhibits inductive properties as a whole system. The load L is installed, for example, on the ceiling, which is an example of building material. Although one load L is shown in the figure, it is not limited to this, and the load L may consist of multiple devices connected in parallel to each other. The load L is operated and controlled by the AC waveform of the AC power supply AC and the switch device 1.

[0025] Switch device 1 controls the operation of load L by switching the supply of power output from AC power source on or off. Switch device 1 is installed, for example, on a wall, which is an example of building material.

[0026] The switch device 1 has an information acquisition unit 70 that acquires operation information for operating a load L. The information acquisition unit 70 acquires operation information related to dimming the lighting fixture, for example, when the load L is a lighting fixture. The information acquisition unit 70 is, for example, a touch panel and button switches that accept user operation input, or an environmental sensor that detects temperature and humidity. The information acquisition unit 70 may also be a communication module that acquires operation information by wireless and infrared communication.

[0027] The switch device 1 controls the operation of the load L based on the operation information acquired by the information acquisition unit 70.

[0028] As shown in Figure 3, the switch device 1 includes a first terminal T1, a second terminal T2, a first semiconductor switch 10, a second semiconductor switch 20, a power supply circuit 30, and a control unit 50. The control unit 50 of the switch device 1 controls the conduction and deconduction of the first semiconductor switch 10, as well as the ON command and release of the ON command for the second semiconductor switch 20, based on the above operation information.

[0029] The first terminal T1 and the second terminal T2 are located in the power supply path SL connecting the AC power source and the load L. In this example, the first terminal T1 is located on the AC power source side of the second terminal T2, and the second terminal T2 is located on the load L side of the first terminal T1. In other words, the first terminal T1 is located on the AC power source side of the first semiconductor switch 10, and the second terminal T2 is located on the load L side of the first semiconductor switch 10.

[0030] The first semiconductor switch 10 is provided between the first terminal T1 and the second terminal T2 in the power supply path SL. The first semiconductor switch 10 is composed of two field-effect transistors 11 and 12 connected in series with 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, the gate of one field-effect transistor 11 is connected to the control unit 50, the drain is connected to the first terminal T1, and the source is connected to the other field-effect transistor. It is connected to the source of the other field-effect transistor 12. The gate of the other field-effect transistor 12 is connected to the control unit 50, the drain is connected to the second terminal T2, and the source is connected to the other field-effect transistor 11 It is connected to the source.

[0032] The first semiconductor switch 10 switches between a conduction state and a non-conduction 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 instantly become conduction in response to an ON command from the first gate signal s1, and instantly become non-conduction in response to an OFF command from the first gate signal s1. The first semiconductor switch 10 remains non-conduction after becoming non-conduction until the next ON command is received.

[0033] The second semiconductor switch 20 is connected in parallel to the first semiconductor switch 10. Specifically, one end of the second semiconductor switch 20 is connected to 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 node n2 between the first semiconductor switch 10 and the second terminal T2. In this example, the first terminal T1 and node n1 are at the same potential, and the second terminal T2 and node n2 are at the same potential.

[0034] 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 conduction state and a non-conduction 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 conduction when it receives an ON command from the second gate signal s2. On the other hand, when the second semiconductor switch 20 receives the release of the ON command from the second gate signal s2, it does not immediately become non-conduction, but maintains a conduction state as long as current is flowing through it, and becomes non-conduction when the current flowing through it becomes zero. The second semiconductor switch 20 remains non-conduction after becoming non-conduction until the next ON command is received.

[0035] The power supply circuit 30 is a circuit that generates a drive voltage (operating voltage) to drive the control unit 50. The power supply circuit 30 is electrically connected to the first terminal T1 via the first rectifier element 31 and to the second terminal T2 via the second rectifier element 32. The anode of the first rectifier element 31 is connected to the first terminal T1, and its cathode is connected to the power supply circuit 30 via node n3 located between the first rectifier element 31 and the power supply circuit 30. The anode of the second rectifier element 32 is connected to the second terminal T2, and its cathode is connected to the power supply circuit 30 via node n3. The power supply circuit 30 obtains power from either the first terminal T1 or the second terminal T2 using an AC power supply as its power source. The power supply circuit 30 converts the power obtained from either the first terminal T1 or the second terminal T2 into a predetermined DC voltage and outputs it to the control unit 50 as a drive voltage.

[0036] As shown in Figure 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.

[0037] 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 conduction and non-conductivity of the first semiconductor switch 10.

[0038] 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 an ON command release to the second semiconductor switch 20.

[0039] The MCU55 controls the switching of the first semiconductor switch 10 between conduction and non-conductivity, and the switching of the output for the second semiconductor switch 20 to an ON command and an ON command release, at predetermined intervals. The predetermined interval is, for example, half the interval of the AC waveform of the AC power supply. The predetermined interval may be the same as the interval of the AC waveform of the AC power supply, or it may be a multiple of half the interval of the AC waveform.

[0040] For example, during a half-cycle, the MCU 55 activates the first gate circuit 51 to output a first gate signal s1, switching the conduction and non-conduction of the first semiconductor switch 10. Also during a half-cycle, the MCU 55 activates the second gate circuit 52 to output a second gate signal s2, switching the output of an ON command and a release of the ON command for the second semiconductor switch 20. The reason for releasing the ON command is to prevent the second semiconductor switch 20 from becoming conductive at the start of the next half-cycle. In this way, the MCU 55 controls the operation of the load L by activating the first gate circuit 51 and the second gate circuit 52 and controlling the opening and closing of the first semiconductor switch 10 and the second semiconductor switch 20.

[0041] Figure 4 is a timing chart showing the operation of the switch device 1.

[0042] The figure shows the first gate signal s1 received by the first semiconductor switch 10, the second gate signal s2 received by the second semiconductor switch 20, the terminal voltages between the first terminal T1 and the second terminal T2, and the load current supplied to the load L. When the terminal voltage is 0, load current is supplied to the load L.

[0043] The figure also shows a timing chart related to the completion of securing the drive voltage for driving the control unit 50. The power supply circuit 30 generates the drive voltage when the AC current of the AC power supply 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 30 has been able to generate a sufficient drive voltage, it outputs a drive voltage securing completion signal to the control unit 50 to indicate that the drive voltage has been secured.

[0044] The control unit 50 controls the semiconductor switch via a gate circuit upon receiving a signal indicating that the drive voltage has been secured. 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.

[0045] In the switch device 1 of this embodiment, the following control is performed to suppress the generation of back electromotive force due to the load L when the first semiconductor switch 10 is turned off.

[0046] For example, after the control unit 50 turns the first semiconductor switch 10 on (t=t1), it outputs an ON command and a release command to the second semiconductor switch 20 so as to span the falling edge from on to off (t=t2). Specifically, the control unit 50 turns the second semiconductor switch 20 on by outputting an ON command before switching the first semiconductor switch 10 from on to off. With this control, when the first semiconductor switch 10 becomes off, the current from the AC power supply 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, current is supplied to the load L, and the generation of back electromotive force by the load L can be suppressed. This suppresses malfunctions in the first semiconductor switch 10.

[0047] Furthermore, the control unit 50 outputs a release of the ON command to the second semiconductor switch 20 after switching the first semiconductor switch 10 to non-conductive mode and before the current of the AC power supply becomes zero. After receiving the release of the ON command, the second semiconductor switch 20 does not immediately become non-conductive, but maintains a conductive state as long as current is flowing through it, and changes from a conductive state to a non-conductive state when the current flowing through it becomes zero (t=t0). Therefore, even after the second semiconductor switch 20 receives the release of the ON command, current continues to be supplied to the load L in accordance with the AC waveform until the current becomes zero, thereby suppressing the generation of back electromotive force due to the load L. This suppresses malfunctions in the first semiconductor switch 10.

[0048] (Embodiment 2) The switch device 1A according to Embodiment 2 will be described with reference to Figure 5. Embodiment 2 describes an example in which the switch device 1A is equipped with a voltage detection unit 58.

[0049] Figure 5 is a circuit diagram of the switch device 1A and load control system 2A according to Embodiment 2.

[0050] The load control system 2A of Embodiment 2 comprises an AC power supply AC, a load L, and a switch device 1A. The AC power supply AC and the load L are the same as in Embodiment 1. The information acquisition unit 70 of the switch device 1A is also the same as in Embodiment 1.

[0051] The switch device 1A of Embodiment 2 includes a first terminal T1, a second terminal T2, a first semiconductor switch 10, a second semiconductor switch 20, a power supply circuit unit 30, and a control unit 50A. The first semiconductor switch 10, the second semiconductor switch 20, and the power supply circuit unit 30 are the same as those in Embodiment 1.

[0052] As shown in Figure 5, the control unit 50A of Embodiment 2 includes a first gate circuit 51, a second gate circuit 52, and an MCU 55, and further includes a voltage detection unit 58.

[0053] The first gate circuit 51 is the same as in Embodiment 1. During half a cycle, the MCU 55 activates the first gate circuit 51 to output a first gate signal s1, which switches the first semiconductor switch 10 between conducting and not conducting. In other words, the MCU 55 controls the operation of the load L by activating the first gate circuit 51 and controlling the opening and closing of the first semiconductor switch 10.

[0054] The voltage detection unit 58 is a circuit that detects the voltage applied to the first semiconductor switch 10. The voltage detection unit 58 is electrically connected to the first terminal T1 and the second terminal T2, respectively. Specifically, the voltage detection unit 58 is connected to the first terminal T1 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 second terminal T2 via the second rectifier element 32 and detects the potential at the second terminal T2.

[0055] In the switch device 1A of Embodiment 2, the voltage detection unit 58 and the second gate circuit 52 are connected, and the voltage detection unit 58 controls the operation of the second gate circuit 52.

[0056] The voltage detection unit 58 activates the second gate circuit 52 and outputs an ON command to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage. The predetermined voltage is set to a voltage less than or equal to the allowable voltage of the first semiconductor switch 10.

[0057] In other words, the control unit 50A of Embodiment 2 uses the voltage detection unit 58 to detect that the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, and outputs an ON command to the second semiconductor switch 20. To put it another way, the control unit 50A outputs an ON command to the second semiconductor switch 20 and causes the second semiconductor switch 20 to conduct when the potential at the first terminal T1 or the second terminal T2 is higher than a predetermined potential.

[0058] In the switch device 1A of Embodiment 2, an ON command is output to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage. By making the second semiconductor switch 20 conduct when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, it is possible to suppress the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0059] (Modified version of Embodiment 2) A modified switch device 1B of Embodiment 2 will be described with reference to Figure 6. In the modified embodiment of Embodiment 2, an example will be described in which the second semiconductor switch 20 is controlled by the MCU 55 and the voltage detection unit 58, respectively.

[0060] Figure 6 is a circuit diagram of a switch device 1B and a load control system 2B according to a modified example of Embodiment 2.

[0061] The modified load control system 2B comprises an AC power supply, a load L, and a switch device 1B. The AC power supply and load L are the same as in Embodiment 1. The information acquisition unit 70 of the switch device 1B is also the same as in Embodiment 1.

[0062] The modified switch device 1B includes a first terminal T1, a second terminal T2, a first semiconductor switch 10, a second semiconductor switch 20, a power supply circuit 30, and a control unit 50B. The first semiconductor switch 10, the second semiconductor switch 20, and the power supply circuit 30 are the same as in Embodiment 1.

[0063] The modified control unit 50B includes a first gate circuit 51, a second gate circuit 52, an MCU 55, and a voltage detection unit 58.

[0064] The first gate circuit 51, MCU 55, and voltage detection unit 58 are in the embodiment 2 It is similar to that.

[0065] In the modified configuration, the MCU 55 and the voltage detection unit 58 are each connected to the second gate circuit 52, and control the operation of the second gate circuit 52.

[0066] The MCU 55 controls the operation of the load L by activating the first gate circuit 51 and the second gate circuit 52, thereby controlling the opening and closing of the first semiconductor switch 10 and the second semiconductor switch 20. The voltage detection unit 58 activates the second gate circuit 52 and outputs an ON command to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage.

[0067] The switch device 1B, a modified version of Embodiment 2, has the effects of both Embodiment 1 and Embodiment 2. In other words, the switch device 1B can suppress the generation of back electromotive force due to the load L when the first semiconductor switch 10 is turned off. Furthermore, even if back electromotive force due to the load L is generated, it can suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0068] (Embodiment 3) The switch device 1C according to Embodiment 3 will be described with reference to Figure 7. Embodiment 3 describes an example in which the switch device 1C is equipped with an electromagnetic relay 40.

[0069] Figure 7 is a circuit diagram of the switch device 1C and load control system 2C according to Embodiment 3.

[0070] The load control system 2C of Embodiment 3 comprises an AC power supply AC, a load L, and a switch device 1C. The AC power supply AC and the load L are the same as in Embodiment 2. The information acquisition unit 70 of the switch device 1C is also the same as in Embodiment 2.

[0071] The switch device 1C of Embodiment 3 includes a first terminal T1, a second terminal T2, a first semiconductor switch 10, a second semiconductor switch 20, a power supply circuit unit 30, a control unit 50C, and a voltage detection unit 58. The first semiconductor switch 10, the second semiconductor switch 20, the power supply circuit unit 30, and the voltage detection unit 58 are the same as those in Embodiment 2. The voltage detection information from the voltage detection unit 58 is output not only to the second gate circuit 52 but also to the MCU 55.

[0072] The switch device 1C shown in Figure 7 includes an electromagnetic relay 40. The electromagnetic relay 40 is, for example, a normally open type contact relay. The electromagnetic relay 40 is provided between the first semiconductor switch 10 and the second terminal T2 in the power supply path SL. The electromagnetic relay 40 is connected in series with the first semiconductor switch 10. In the figure, the electromagnetic relay 40 is located on the load L side when viewed from the first semiconductor switch 10, but it is not limited to this, and may be located on the AC side when viewed from the first semiconductor switch 10. That is, the electromagnetic relay 40 may be provided between the first semiconductor switch 10 and the first terminal T1 in the power supply path SL.

[0073] 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 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 node n2 between the electromagnetic relay 40 and the second terminal T2.

[0074] In Embodiment 3, one end of the voltage detection unit 58 is connected to node n1, while the other end is connected to node n1a between the first semiconductor switch 10 and the electromagnetic relay 40. The voltage detection unit 58 is configured to detect the potential at either end of the first semiconductor switch 10 (node ​​n1 or n1a).

[0075] The control unit 50C keeps the electromagnetic relay 40 in a conductive state during normal operation, and deconducts (shuts off) the electromagnetic relay when an overvoltage occurs. For example, the control unit 50C uses the voltage detection unit 58 to detect that the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, and then deconducts the electromagnetic relay 40, which is currently in a conductive state.

[0076] In the switch device 1C of Embodiment 3, the electromagnetic relay 40 is de-conducted when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage. Therefore, it is possible to suppress the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0077] Furthermore, in the switch device 1C of Embodiment 3, the field-effect transistors 11 and 12 and the electromagnetic relay 40 are connected in series, so low-voltage field-effect transistors 11 and 12 can be used. This makes it possible to reduce the on-resistance of the first semiconductor switch 10.

[0078] Furthermore, even if the electromagnetic relay 40 cannot be intentionally de-conducted due to contact welding or other reasons, the voltage detection unit 58 can be used to detect when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, and an ON command can be output to the second semiconductor switch 20, thereby causing the second semiconductor switch 20 to conduct. This prevents overvoltage from being applied to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to prevent malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0079] (Modified example of Embodiment 3) A modified example of the third embodiment, the switch device 1D, will be described with reference to Figure 8. In the modified example of the third embodiment, an example will be described in which the second semiconductor switch 20 is controlled by the MCU 55 and the voltage detection unit 58, respectively.

[0080] Figure 8 is a circuit diagram of a switch device 1D and a load control system 2D according to a modified example of Embodiment 3.

[0081] This modified load control system 2D comprises an AC power supply AC, a load L, and a switch device 1D. The AC power supply AC and the load L are the same as in the modified embodiment 2. The information acquisition unit 70 of the switch device 1D is also the same as in the modified embodiment 2.

[0082] This modified switch device 1D includes a first terminal T1, a second terminal T2, a first semiconductor switch 10, a second semiconductor switch 20, a power supply circuit 30, and a control unit 50D. The first semiconductor switch 10, the second semiconductor switch 20, and the power supply circuit 30 are the same as those in the modified embodiment 2.

[0083] The modified control unit 50D includes a first gate circuit 51, a second gate circuit 52, an MCU 55, and a voltage detection unit 58.

[0084] The first gate circuit 51, MCU 55, and voltage detection unit 58 are the same as those in the modified example of Embodiment 2.

[0085] In this modified version, the voltage detection unit 58 and the MCU 55 are each connected to the second gate circuit 52, and control the operation of the second gate circuit 52.

[0086] The MCU 55 controls the operation of the load L by activating the first gate circuit 51 and the second gate circuit 52, thereby controlling the opening and closing of the first semiconductor switch 10 and the second semiconductor switch 20. The voltage detection unit 58 activates the second gate circuit 52 and outputs an ON command to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage.

[0087] The switch device 1D according to a modification of Embodiment 3 has the same effects as Embodiments 1, 2, and 3. In other words, the switch device 1D can suppress the generation of back electromotive force due to the load L when the first semiconductor switch 10 is turned off. Furthermore, even if back electromotive force due to the load L is generated, it can suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0088] (summary) The configuration of the switch device according to this embodiment is illustrated below.

[0089] [Example 1] The switch device 1 according to this embodiment 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, a second semiconductor switch 20 connected in parallel to the first semiconductor switch 10, and a control unit 50 that switches the conduction and non-conduction of the first semiconductor switch 10, and switches the output of an ON command and a release of the ON command to the second semiconductor switch 20 at predetermined intervals. The control unit 50 puts the second semiconductor switch 20 into a conduction state by outputting an ON command to the second semiconductor switch 20 before switching the first semiconductor switch 10 from conduction to non-conduction, and 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-conduction.

[0090] In this way, 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 AC power supply current 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, current is supplied to the load L, and the generation of back electromotive force by the load L can be suppressed. This suppresses malfunctions in the first semiconductor switch 10.

[0091] Furthermore, after switching the first semiconductor switch 10 to a non-conductive state, before the current of the AC power supply becomes zero, the second semiconductor switch 20 outputs a release of the ON command. In response, after receiving the release of the ON command, the second semiconductor switch 20 does not immediately become non-conductive, but maintains a conductive state as long as current is flowing through it, and changes from a conductive state to a non-conductive state when the current flowing through it becomes zero. Therefore, even after the second semiconductor switch 20 receives the release of the ON command, current continues to be supplied to the load L until the current becomes zero, and the generation of back electromotive force due to the load L can be suppressed. This can suppress malfunctions in the first semiconductor switch 10.

[0092] [Example 2] The first semiconductor switch 10 is a switch that includes field-effect transistors 11 and 12. The second semiconductor switch 20 is a thyristor or a bidirectional thyristor.

[0093] The first semiconductor switch 10 allows for instantaneous switching between conduction and non-conductivity. The second semiconductor switch 20 becomes conductive upon receiving an ON command, and upon receiving a cancellation of the ON command, it does not immediately become non-conductive, but maintains the conductive state as long as current is flowing through it, and becomes non-conductive when the current flowing through it becomes zero. The second semiconductor switch 20 can suppress the generation of back electromotive force due to the load L when the first semiconductor switch 10 is turned off. The configuration of Example 2 is applicable to Example 1.

[0094] [Example 3] The second semiconductor switch 20 maintains a conductive state even after receiving the cancellation of the ON command output from the control unit 50, and changes from a conductive state to a non-conductive state when the current of the AC power supply becomes zero.

[0095] This second semiconductor switch 20 becomes conductive upon receiving an ON command, and upon receiving a cancellation of the ON command, it does not immediately become non-conductive but maintains a conductive state as long as current is flowing through it, and becomes non-conductive when the current flowing through it becomes zero. This second semiconductor switch 20 can suppress the generation of back electromotive force due to the load L when the first semiconductor switch 10 is turned off. The configuration of Example 3 is applicable to Example 1 or 2.

[0096] [Example 4] The switch device 1 further includes a power supply circuit 30 that generates a drive voltage for driving the control unit 50. The power supply circuit 30 is electrically connected to the first terminal T1 via a first rectifier element 31 and to the second terminal T2 via a second rectifier element 32.

[0097] According to this, the control unit 50 can be driven stably, and the control of the first semiconductor switch 10 and the second semiconductor switch 20 can be performed stably. This makes it possible to suppress malfunctions in the first semiconductor switch 10. The configuration of Example 4 is applicable to any of Examples 1 to 3.

[0098] [Example 5] The control unit 50A (or 50B) of the switch device 1A (or 1B) has a voltage detection unit 58 that detects the voltage applied to the first semiconductor switch 10, and outputs an ON command to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage.

[0099] According to this, when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, an ON command is output to the second semiconductor switch 20, causing the second semiconductor switch 20 to conduct, thereby suppressing the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force. The configuration of Example 5 is applicable to any of Examples 1 to 4.

[0100] [Example 6] The voltage detection unit 58 is electrically connected to the first terminal T1 and the second terminal T2, respectively. The control unit 50A (or 50B) outputs an ON command to the second semiconductor switch 20 when the potential at the first terminal T1 or the second terminal T2 is higher than a predetermined potential.

[0101] According to this, when the potential at the first terminal T1 or the second terminal T2 is higher than a predetermined potential, an ON command is output to the second semiconductor switch 20, causing the second semiconductor switch 20 to conduct, thereby suppressing the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force. The configuration of Example 6 is applicable to Example 5.

[0102] [Example 7] The switch device 1C (or 1D) further includes an electromagnetic relay 40 provided between the first semiconductor switch 10 and the second terminal T2 in the power supply path SL. The electromagnetic relay 40 is connected in series with the first semiconductor switch 10.

[0103] According to this, for example, if the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, the electromagnetic relay 40 can be made non-conductive, thereby suppressing the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0104] Furthermore, by connecting the first semiconductor switch 10 and the electromagnetic relay 40 in series, a first semiconductor switch 10 with low voltage resistance can be used. This reduces the on-resistance of the first semiconductor switch 10. The configuration of Example 7 is applicable to any of Examples 1 to 6.

[0105] [Example 8] The control unit 50C (or 50D) has a voltage detection unit 58 that detects the voltage applied to the first semiconductor switch 10, and when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, it turns the electromagnetic relay 40, which is in a conductive state, into a non-conductive state.

[0106] In this way, by making the electromagnetic relay 40 non-conductive when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, it is possible to suppress the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force. The configuration of Example 8 is applicable to Example 7.

[0107] [Example 9] The second semiconductor switch 20 is connected in parallel to the first semiconductor switch 10 and the electromagnetic relay 40. The control unit 50C (or 50D) outputs an ON command to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage.

[0108] With this configuration, for example, even if it is not possible to intentionally de-conduct the electromagnetic relay 40, it is possible to detect that the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, output an ON command to the second semiconductor switch 20, and cause the second semiconductor switch 20 to conduct. This prevents overvoltage from being applied to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to prevent malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force. The configuration of Example 9 is applicable to Example 8.

[0109] [Example 10] The switch device 1 further includes an information acquisition unit 70 for acquiring operation information for operating the load L. The control unit 50 controls the conduction and deconduction of the first semiconductor switch 10, as well as the on command and release of the on command for the second semiconductor switch 20, based on the operation information.

[0110] According to this, the load L can be appropriately controlled according to the operation information. The configuration of Example 10 is applicable to any of Examples 1 to 9.

[0111] [Example 11] The switch device 1 further includes an information acquisition unit 70 for acquiring operation information for operating the load L. The control unit 50 controls the conduction and deconduction of the first semiconductor switch 10, the on command and release of the on command for the second semiconductor switch 20, and the conduction and deconduction of the electromagnetic relay 40 based on the operation information.

[0112] According to this, the load L can be appropriately controlled according to the operation information. The configuration of Example 11 is applicable to Example 8 or Example 9.

[0113] Furthermore, the switch device according to this embodiment may have the following configuration.

[0114] [Example 12] The switch device 1A according to this embodiment 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, a second semiconductor switch 20 connected in parallel to the first semiconductor switch 10, and a control unit 50A that switches the conduction and non-conductivity of the first semiconductor switch 10, and switches the output of an ON command and the release of the ON command for the second semiconductor switch 20. The control unit 50A outputs an ON command to the second semiconductor switch 20 when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage.

[0115] In this way, when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, an ON command is output to the second semiconductor switch 20, thereby causing the second semiconductor switch 20 to conduct and preventing an overvoltage from being applied to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to prevent the first semiconductor switch 10 from malfunctioning due to the generated back electromotive force.

[0116] [Example 13] The switch device 1C according to this embodiment 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 semiconductor switch 10 and the second terminal T2 in the power supply path SL, and a control unit 50C that switches the conduction and non-conduction of the first semiconductor switch 10. The control unit 50C sets the electromagnetic relay 40, which is in a conduction state, to a non-conduction state when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage.

[0117] In this way, by making the electromagnetic relay 40 non-conductive when the voltage applied to the first semiconductor switch 10 is higher than a predetermined voltage, it is possible to suppress the application of an overvoltage to the first semiconductor switch 10. As a result, even if a back electromotive force is generated by the load L, it is possible to suppress malfunctions in the first semiconductor switch 10 caused by the generated back electromotive force.

[0118] (Other forms) Although the switch device has been described above based on embodiments, the present invention is not limited to the above embodiments. For example, the present invention also includes forms obtained by applying various modifications to the above embodiments that a person skilled in the art could conceive, and forms realized by arbitrarily combining the components and functions in the embodiments without departing from the spirit of the present invention.

[0119] For example, in Embodiment 1, if the second semiconductor switch 20 does not immediately become conductive after receiving an ON command, that is, if a predetermined transition time is required for the second semiconductor switch 20 to become conductive after receiving an ON command, it is desirable that the timing for outputting the ON command to the second semiconductor switch 20 is at least a predetermined transition time earlier than when the first semiconductor switch 10 is switched to a non-conductive state (t=t2).

[0120] Embodiment 2 shows an example in which the voltage detection unit 58 is included in the control unit 50, but it is not limited to that. The voltage detection unit 58 may be provided outside the control unit 50 as a separate component from the control unit 50. In that case, the driving power for the voltage detection unit 58 may be supplied from the power supply circuit unit 30. Also, Embodiment 2 shows an example in which the voltage detection unit 58 is provided outside the MCU 55 as a separate component from the MCU 55, but it is not limited to that. The voltage detection unit 58 may be provided inside the MCU 55. That is, the MCU 55 may have the function of the voltage detection unit 58.

[0121] Embodiment 3 shows an example where the electromagnetic relay 40 is made non-conductive using the MCU 55, but it is not limited to this. For example, the conduction and non-conductivity of the electromagnetic relay 40 may be controlled by an external circuit connected to the voltage detection unit. [Explanation of symbols]

[0122] 1, 1A, 1B, 1C, 1D Switching Device 10. First semiconductor switch 20. Second semiconductor switch 30 Power supply circuit section 31 First rectifier element 32 Second rectifier element 40 Electromagnetic relays 50, 50A, 50B, 50C, 50D Control Unit 58 Voltage detection unit 70 Information acquisition department AC alternating current power supply L load SL power supply route T1 First terminal T2 Second terminal

Claims

1. A first terminal and a second terminal are provided in the power supply path connecting the AC power source and the load, A first semiconductor switch is provided between the first terminal and the second terminal in the power supply path, A second semiconductor switch connected in parallel to the first semiconductor switch, A control unit that, at each half-cycle or multiplier of the half-cycle appearing in the AC waveform of the AC power supply, switches the conduction and non-conduction of the first semiconductor switch, and switches the output of an ON command and an ON command release for the second semiconductor switch, Equipped with, The control unit, before switching the first semiconductor switch from conductive to non-conductive, outputs an ON command to the second semiconductor switch, thereby making the second semiconductor switch conductive. After switching the first semiconductor switch to non-conductive, and before the current flowing to the load by the AC power supply becomes zero, the control unit outputs a release of the ON command to the second semiconductor switch at the same timing during the half-cycle or the half-cycle multiplication. Switching device.

2. The first semiconductor switch is a switch that includes a field-effect transistor, The second semiconductor switch is a thyristor or a bidirectional thyristor. The switch device according to claim 1.

3. The second semiconductor switch maintains a conductive state even after receiving the cancellation of the ON command output from the control unit, and switches from a conductive state to a non-conductive state when the current of the AC power supply becomes zero. The switch device according to claim 1.

4. Furthermore, it includes a power supply circuit that generates a drive voltage for driving the control unit, The power supply circuit is electrically connected to the first terminal via a first rectifier element and to the second terminal via a second rectifier element. The switch device according to claim 1.

5. The control unit includes a voltage detection unit that detects the voltage applied to the first semiconductor switch, and outputs an ON command to the second semiconductor switch when the voltage applied to the first semiconductor switch is higher than a predetermined voltage. The switch device according to claim 1.

6. The voltage detection unit is electrically connected to the first terminal and the second terminal, The control unit outputs an ON command to the second semiconductor switch when the potential at the first terminal or the second terminal is higher than a predetermined potential. The switch device according to claim 5.

7. Furthermore, the power supply path includes an electromagnetic relay provided between the first semiconductor switch and the second terminal, The electromagnetic relay is connected in series with the first semiconductor switch. The switch device according to claim 1.

8. The control unit includes a voltage detection unit that detects the voltage applied to the first semiconductor switch, and when the voltage applied to the first semiconductor switch is higher than a predetermined voltage, it deactivates the electromagnetic relay which is currently in a conductive state. The switch device according to claim 7.

9. The second semiconductor switch is connected in parallel to the first semiconductor switch and the electromagnetic relay. The control unit outputs an ON command to the second semiconductor switch when the voltage applied to the first semiconductor switch is higher than a predetermined voltage. The switch device according to claim 8.

10. Furthermore, it includes an information acquisition unit that acquires operation information for operating the load, The control unit controls the conduction and deconduction of the first semiconductor switch, as well as the on command and release command for the second semiconductor switch, based on the operation information. The switch device according to claim 1.

11. Furthermore, it includes an information acquisition unit that acquires operation information for operating the load, The control unit controls the conduction and deconduction of the first semiconductor switch, the on command and release of the on command for the second semiconductor switch, and the conduction and deconduction of the electromagnetic relay based on the operation information. The switch device according to claim 7.

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