JP7555048B2 - Load Control Device - Google Patents

Description

The present disclosure relates generally to a load control device, and more specifically to a load control device having a switch unit that is inserted between a power source and a load.

Patent Document 1 discloses a dimmer device (load control device) that includes a switch unit connected in series with a load to an AC power source, a control unit, and a control power source unit. The control unit controls the on/off state of the switch unit to switch between a state in which the load is turned on (a power supply state in which power is supplied to the load) and a state in which the load is turned off (a state in which power supply to the load is cut off). The control power source unit converts the AC power source into a specified control power source. The control power source unit has a capacitive element (power storage unit) that accumulates the control power source. The control unit receives control power (internal circuit) from the control power source unit via the capacitive element.

When this dimmer turns on the load, the switch unit is turned off midway through each half cycle of the AC voltage to cut off electrical continuity to the load, and while the switch unit is off, the control power supply unit generates control power from the AC power supply.

JP 2013-149498 A

In the light control device of Patent Document 1, if a large current flows through the power storage unit when switching from a power supply state in which power is supplied to the load to a cut-off state in which power supply to the load is cut off, the load may momentarily malfunction, and the operation of the load may become unstable.

The objective of the present disclosure is to provide a load control device that can prevent the operation of a load from becoming unstable when switching from a power supply state in which power is supplied to the load to a cut-off state in which the power supply to the load is cut off.

A load control device according to an aspect of the present disclosure includes a pair of connection terminals, a switch unit, an internal circuit, a power storage unit for supplying power to the internal circuit, a first power supply unit, a second power supply unit, and a third power supply unit. The pair of connection terminals are connected to a series circuit of an AC power source and a load. The switch unit is connected between the pair of connection terminals. The internal circuit includes at least a control unit that controls on/off of the switch unit. The first power supply unit includes a DC/DC converter connected between the pair of connection terminals and the power storage unit. The first power supply unit charges the power storage unit by applying an output voltage of the DC/DC converter to the power storage unit in a cut-off state in which power supply from the AC power source to the load is cut off. The second power supply unit charges the power storage unit by forming a charging path with a lower impedance than that of the first power supply unit between the pair of connection terminals and the power storage unit in a power supply state in which power is supplied from the AC power source to the load. The third power supply unit converts the voltage across the power storage unit to generate power for operating the internal circuit. A current limiting unit that limits a current value to a predetermined value or less is connected between the power storage unit and the third power supply unit. The power storage unit is a first power storage unit. A second power storage unit is connected between the third power supply unit and the current limiting unit. The load control device includes a series circuit of a Zener diode and a switch element connected between both ends of the second power storage unit. The control unit controls the switch element to a conductive state when the switch unit is in a conductive state.

According to the present disclosure, it is possible to prevent the operation of a load from becoming unstable when switching from a power supply state in which power is supplied to a load to a cut-off state in which the power supply to the load is cut off.

FIG. 1 is a schematic circuit diagram of a load control device according to one embodiment of the present disclosure. FIG. 2 is a timing chart showing the operation of the load control device.

(Embodiment)
(1) Overview Hereinafter, an overview of a load control device 1 according to an embodiment will be described with reference to FIG.

As shown in FIG. 1, the load control device 1 according to this embodiment includes a switch unit 11 that is inserted between the AC power source 2 and the load 3. In this disclosure, "insertion" means insertion between two electrically connected entities, and the switch unit 11 is electrically connected between the AC power source 2 and the load 3 in a circuit made up of the AC power source 2 and the load 3. In other words, the load 3 is electrically connected to the AC power source 2 via the switch unit 11.

The switch unit 11 is realized by a semiconductor switch such as a transistor or a bidirectional thyristor. In this embodiment, the load control device 1 is a so-called electronic switch that electronically switches between conduction and non-conduction between the AC power source 2 and the load 3 by electronically controlling the switch unit 11. The load control device 1 has a pair of connection terminals TA1 and TA2 to which the series circuit of the AC power source 2 and the load 3 is connected, and the switch unit 11 is electrically connected between the pair of connection terminals TA1 and TA2. In other words, inside the load control device 1, the connection terminals TA1 and TA2 are electrically connected via the switch unit 11. One connection terminal TA1 is connected to the AC power source 2, and the other connection terminal TA2 is connected to the load 3, so that the switch unit 11 is inserted between the AC power source 2 and the load 3.

According to this configuration, the load control device 1 can control the energization state (power supply state) from the AC power source 2 to the load 3 by the switch unit 11. Basically, when the operation state of the switch unit 11 is in a conductive state, the connection terminal TA1 and the connection terminal TA2 are conductive via the switch unit 11, and when the operation state of the switch unit 11 is in a cut-off state, the connection terminal TA1 and the connection terminal TA2 are not conductive. In other words, when the switch unit 11 is in a conductive state, the load control device 1 is in a power supply state in which power is supplied from the AC power source 2 to the load 3. Also, when the switch unit 11 is in a cut-off state, the load control device 1 is in a cut-off state in which the supply of power from the AC power source 2 to the load 3 is cut off. In other words, the load control device 1 of this embodiment functions as a switch that switches between a power supply state in which power is supplied to the load 3 and a cut-off state in which the supply of power to the load 3 is cut off. The load control device 1 may have a dimming function that adjusts the brightness of the load 3, which is a lighting load, by controlling the timing at which the switch unit 11 turns on or off depending on the dimming level, but it is not essential that the load control device 1 has a dimming function.

The load control device 1 according to this embodiment further includes an internal circuit 12, a power storage unit (first power storage unit) C1 for supplying power to the internal circuit 12, a first power supply unit 13, and a second power supply unit 14. The internal circuit 12 includes a control unit 121 that controls the switch unit 11, etc.

The first power supply unit 13 includes a DC/DC converter 132 connected between a pair of connection terminals TA1, TA2 and the power storage unit C1. In a cut-off state in which the power supply from the AC power source 2 to the load 3 is cut off, the first power supply unit 13 charges the power storage unit C1 by applying the output voltage of the DC/DC converter 132 to the power storage unit C1. In the drawings, the DC/DC converter 132 is simply referred to as "DC/DC".

In a power supply state in which the second power supply unit 14 supplies power from the AC power source 2 to the load 3, the second power supply unit 14 forms a charging path with a lower impedance than the first power supply unit 13 between the pair of connection terminals TA1, TA2 and the power storage unit C1, and charges the power storage unit C1.

In this embodiment, the power storage unit C1 for supplying power to the internal circuit 12 is charged by the first power supply unit 13 in the cutoff state, and is charged by the second power supply unit 14 in the power supply state.

In the power supply state, the power storage unit C1 is charged by the second power supply unit 14, so it is possible to prevent a large current from flowing to the first power supply unit 13 to charge the power storage unit C1, compared to when no charge has accumulated in the power storage unit C1 at the time of switching from the power supply state to the cutoff state. This prevents a large current from flowing to the load 3, reducing the possibility of the load 3 temporarily malfunctioning and preventing the operation of the load 2 from becoming unstable. For example, if the load 3 is a lighting load, it is possible to reduce the possibility of the load 3 temporarily erroneously lighting up when the load 3 is switched from a lit state to an off state.

In addition, the time required to charge the power storage unit C1 can be shortened compared to when no charge has accumulated in the power storage unit C1 at the time of switching from the power supply state to the cut-off state. Therefore, in the cut-off state, it is possible to quickly supply operating power to the internal circuit 12 using the power storage unit C1 as a power source, and a smooth transition from the power supply state to the cut-off state can be achieved.

In addition, in the cutoff state, the power storage unit C1 is charged by the first power supply unit 13, so the time required to charge the power storage unit C1 can be shortened compared to when no charge has accumulated in the power storage unit C1 at the time of switching from the cutoff state to the power supply state. Therefore, in the power supply state, it is possible to quickly supply operating power to the internal circuit 12 using the power storage unit C1 as a power source, and a smooth transition from the cutoff state to the power supply state can be achieved.

In addition, in the load control device 1 of this embodiment, power for operating the internal circuit 12 is secured from a pair of connection terminals TA1, TA2 for inserting the switch unit 11 between the AC power source 2 and the load 3. In other words, the load control device 1 is a so-called two-wire load control device that can secure power for operating the internal circuit 12 with two electric wires connected to the pair of connection terminals TA1, TA2. In such a two-wire load control device 1, there is no need to provide a power supply terminal for supplying power for operating the internal circuit 12 separately from the pair of connection terminals TA1, TA2, and wiring work when installing the load control device 1 is also simplified.

(2) Details (2.1) Premise In this embodiment, the load control device 1 is fixed to a mounting object of a building. The "mounting object" in this disclosure is an object to which the load control device 1 is fixed, and includes, for example, a structure such as a wall, ceiling, or floor of a building, or fixtures (including fittings) such as a desk, shelf, or counter. The building in which the load control device 1 is installed is, for example, a residential facility such as a detached house or an apartment building, or a non-residential facility such as an office, store, school, factory, hospital, or nursing home.

As an example, in this embodiment, it is assumed that the load control device 1 is a built-in wiring device that is attached to an attachment object, which is a wall of a house. It is also assumed that the AC power source 2 is, for example, a single-phase 100 [V], 60 [Hz] commercial AC power source (system power source). It is also assumed that the load 3 is, for example, a lighting load (lighting fixture) that includes a light source consisting of an LED (Light Emitting Diode) and a lighting circuit that lights the light source. In this load 3, the light source lights up when power is supplied from the AC power source 2.

The load control device 1 also has connection terminals TA1 and TA2 for connecting electric wires. For example, an electric wire routed inside a wall (object to be mounted) is connected to the connection terminals TA1 and TA2, thereby electrically connecting the load control device 1 to the AC power source 2 and the load 3 via the electric wire. The electric wire may be directly connected to the AC power source 2 (system power source, etc.) or indirectly connected via a distribution board, etc.

In addition, the "terminals" of the connection terminals TA1, TA2, etc., referred to in this disclosure do not have to be components for connecting electric wires, etc., and may be, for example, leads of electronic components or parts of conductors included in a circuit board.

In addition, in this disclosure, when comparing two values, "greater than or equal to" includes both the cases where the two values are equal and where one of the two values exceeds the other. However, without being limited to this, "greater than or equal to" here may be synonymous with "greater than," which includes only the cases where one of the two values exceeds the other. In other words, whether or not the cases where the two values are equal can be included can be arbitrarily changed depending on the setting of the reference value, etc., so there is no technical difference between "greater than or equal to" and "greater than." Similarly, "less than" may be synonymous with "less than or equal to."

(2.2) Overall Configuration of the Load Control Device The overall configuration of the load control device 1 according to this embodiment will be described below with reference to FIG.

The load control device 1 includes a pair of connection terminals TA1 and TA2, a switch unit 11, an internal circuit 12 including a control unit 121, a power storage unit C1, a first power supply unit 13, and a second power supply unit 14. In this embodiment, the load control device 1 further includes a third power supply unit 15, a current limiting unit 16, a charge detection unit 17, a level shift circuit 18, and zero cross (denoted as "ZC" in the figure) detection units 191 and 192. Here, the first power supply unit 13, the second power supply unit 14, the third power supply unit 15, the current limiting unit 16, and the power storage unit C1 constitute a power supply circuit 20 that generates power for operating the internal circuit 12 in each of the power supply state and the cut-off state. These components of the load control device 1 are housed in a single housing. In this embodiment, the power supply circuit 20 includes the third power supply unit 15, but the third power supply unit 15 is not an essential component of the load control device 1 and can be omitted as appropriate.

Each of the pair of connection terminals TA1, TA2 is a component to which the electric wire is electrically and mechanically connected. As an example, each of the pair of connection terminals TA1, TA2 is a so-called quick-connect terminal of the wire insertion type in which the electric wire is connected by inserting the electric wire into the terminal hole.

The switch unit 11 is inserted between the AC power supply 2 and the load 3, and switches between conduction and cutoff between the AC power supply 2 and the load 3. In this embodiment, as an example, the switch unit 11 has two MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) Q1 and Q2 electrically connected in series between a pair of connection terminals TA1 and TA2. Each of these two MOSFETs Q1 and Q2 is an enhancement type n-channel MOSFET. The two MOSFETs Q1 and Q2 have their source terminals connected to each other, that is, are connected in what is called an anti-series configuration, and thereby switch between conduction and cutoff for bidirectional current.

The gate terminals of each of the MOSFETs Q1 and Q2 are electrically connected to a level shift circuit 18. The level shift circuit 18 receives a control signal S1 from the control unit 121 (described later) and outputs a control signal S2 to the gate terminals of each of the MOSFETs Q1 and Q2 to drive each of the MOSFETs Q1 and Q2.

As described above, the switch unit 11 has an operating state including a cutoff state and a conductive state. The conductive state includes not only a state in which the switch unit 11 is continuously conductive, but also a state in which the switch unit 11 is intermittently conductive. In other words, in this disclosure, the cutoff state of the switch unit 11 is a state in which the supply of power from the AC power source 2 to the load 3 is cut off, and the conductive state of the switch unit 11 is a state in which power is supplied from the AC power source 2 to the load 3.

Here, it is assumed that the switch unit 11 is in a non-conductive state and an AC voltage is applied to the switch unit 11 from the AC power supply 2. In other words, when the switch unit 11 is non-conductive, the voltage applied across both ends of the switch unit 11 (hereinafter also referred to as the "switch voltage") is approximately equal to the AC voltage Vac from the AC power supply 2. In addition, hereinafter, the polarity of the switch voltage when the connection terminal TA1 is at a high potential is referred to as the "positive polarity," and the polarity of the switch voltage when the connection terminal TA2 is at a high potential is referred to as the "negative polarity."

The zero-cross detection units 191 and 192 are configured to detect the zero-cross points of the voltage between the switches by detecting the magnitude of the voltage between the switches.

The zero-cross detection unit 191 is electrically connected to the connection terminal TA1. The zero-cross detection unit 191 detects the zero-cross point when the switch voltage switches from negative to positive polarity by comparing the absolute value of the voltage between the connection terminal TA1 and ground (reference potential point) with a reference value (e.g., 10 V). In other words, when the zero-cross detection unit 191 detects that the positive switch voltage has transitioned from a state below the reference value to a state equal to or greater than the reference value, it determines that a zero-cross point has occurred.

The zero-cross detection unit 192 is electrically connected to the connection terminal TA2. The zero-cross detection unit 192 detects the zero-cross point when the switch voltage switches from positive to negative polarity by comparing the absolute value of the voltage between the connection terminal TA2 and ground (reference potential point) with a reference value (e.g., 10 V). In other words, when the zero-cross detection unit 192 detects that the negative switch voltage has transitioned from a state below the reference value to a state equal to or greater than the reference value, it determines that a zero-cross point has occurred.

Therefore, the detection timing of the zero-crossing points detected by the zero-crossing detection units 191 and 192 is slightly delayed from the zero-crossing point (0 [V]) in the strict sense.

In this embodiment, a diode D3 is connected between the connection terminal TA1 and the first and second power supply units 13 and 14, and a diode D4 is connected between the connection terminal TA2 and the first and second power supply units 13 and 14. Here, the body diodes D1 and D2 of the MOSFETs Q1 and Q2 and the diodes D3 and D4 form a rectifier DB1. A DC voltage generated by full-wave rectifying the voltage applied to both ends of the switch unit 11 is input to the first and second power supply units 13 and 14.

In this embodiment, the power supply circuit 20, which includes the first power supply unit 13, the second power supply unit 14, and the third power supply unit 15, generates power for operating the internal circuit 12 from the voltage applied to both ends of the switch unit 11. That is, the power supply circuit 20 generates power for operating the internal circuit 12 using the switch voltage as an input. The output voltage V2 of the power supply circuit 20 (specifically, the output voltage of the third power supply unit 15) is applied to the internal circuit 12, whereby power is supplied from the power supply circuit 20 to the internal circuit 12.

Here, the input terminal of the first power supply unit 13 is electrically connected to a pair of connection terminals TA1 and TA2 via diodes D3 and D4, respectively. Similarly, the input terminal of the second power supply unit 14 is electrically connected to a pair of connection terminals TA1 and TA2 via diodes D3 and D4, respectively. The output terminal of the first power supply unit 13 is electrically connected to the storage unit C1. The output terminal of the second power supply unit 14 is electrically connected to the storage unit C1 via diode D5. A current limiting unit 16 is connected between the storage unit C1 and the third power supply unit 15, and a capacitor (second storage unit) C2 is connected between the third power supply unit 15 and the current limiting unit 16. As a result, the capacitor C2 is charged by the voltage VC1 across the storage unit C1, and the third power supply unit 15 converts the voltage VC2 across the capacitor C2 into an output voltage V2, which is a DC voltage of a predetermined voltage value. As a result, the third power supply unit 15 supplies operating power to the internal circuit 12 using the power storage unit C1, which is charged by either the first power supply unit 13 or the second power supply unit 14, as a power source.

In this embodiment, the power supply unit that charges the power storage unit C1 is switched depending on the operating state of the switch unit 11. As described above, the operating state of the switch unit 11 includes a cutoff state in which the supply of power from the AC power source 2 to the load 3 is cut off, and a conduction state in which power is supplied from the AC power source 2 to the load 3. In the cutoff state, the power storage unit C1 is charged by the first power supply unit 13, and in the conduction state, the power storage unit C1 is charged by the second power supply unit 14. In other words, the first power supply unit 13 is a power supply circuit for cutoff time that supplies power to the internal circuit 12 in the cutoff state. The second power supply unit 14 is a power supply circuit for conduction time that supplies power to the internal circuit 12 in the conduction state.

In this manner, in this embodiment, the source of power for the internal circuit 12, i.e., the power supply unit that charges the power storage unit C1, switches between the first power supply unit 13 and the second power supply unit 14 depending on whether the operating state of the switch unit 11 is in the cut-off state or the conductive state. In short, the power supply circuit 20 includes the first power supply unit 13 and the second power supply unit 14 as power supplies that charge the power storage unit C1, and these two power supplies are used depending on whether the switch unit 11 is in the cut-off state or the conductive state.

There is a difference in the characteristics required for the first power supply unit 13 when cut off and the second power supply unit 14 when conduction. In other words, in the first power supply unit 13 when cut off, since the switch unit 11 is in a cut-off state, a relatively high impedance is required to reduce the leakage current flowing between the pair of connection terminals TA1, TA2 through the power supply circuit 20. On the other hand, in the second power supply unit 14 when conduction, since the switch unit 11 is in a conductive state, a relatively low impedance is required to efficiently generate power in the power supply circuit 20. In other words, the second power supply unit 14 is configured to form a charging path with a lower impedance than the first power supply unit 13 in a conductive state.

The components that make up the power supply circuit 20 are described in detail below.

The first power supply unit 13 charges the storage unit C1 in a cut-off state in which the power supply from the AC power supply 2 to the load 3 is cut off. The first power supply unit 13 includes a dropper power supply circuit 131, a capacitor C0, and a DC/DC converter 132.

The dropper power supply circuit 131 steps down the rectified voltage applied to both ends of the switch unit 11. The dropper power supply circuit 131 is composed of a power supply circuit such as a series regulator. A capacitor C0 is connected to the output terminal of the dropper power supply circuit 131, and the capacitor C0 is charged by the output of the dropper power supply circuit 131.

The DC/DC converter 132 includes a switching power supply circuit such as a step-down chopper. The DC/DC converter 132 generates a direct current voltage of a predetermined voltage value (for example, DC 11V) by stepping down the voltage across the capacitor C0. The power storage unit C1 is connected to the output terminal of the DC/DC converter 132, and the power storage unit C1 is charged by the output of the DC/DC converter 132. Here, the capacitor C0 on the primary side of the DC/DC converter 132 is charged at a higher voltage than the power storage unit C1 on the secondary side, and is a small-capacity capacitor. In other words, the voltage VC0 across the capacitor C0 becomes higher than the voltage VC1 across the power storage unit C1, and the current flowing through the primary side of the DC/DC converter 132 decreases. Therefore, the first power supply unit 13 of the load control device 1 generates power for the operation of the internal circuit 12, thereby reducing the current flowing through the load 3, which is a lighting load, and reducing the possibility of the load 3 being erroneously turned on by reducing the current (leak current) flowing through the load 3, which is a lighting load, in the cut-off state.

The second power supply unit 14 charges the power storage unit C1 in a power supply state in which power is supplied from the AC power source 2 to the load 3. The second power supply unit 14 includes a low impedance circuit 141.

The low impedance circuit 141 is inserted between the output terminals (cathodes) of the diodes D3 and D4 and the storage unit C1. The low impedance circuit 141 is composed of a dropper power supply including a bipolar transistor inserted between the output terminals of the diodes D3 and D4 and the storage unit C1. The low impedance circuit 141 forms a charging path for flowing a current flowing through the storage unit C1, that is, a charging current for the storage unit C1, by conducting the bipolar transistor in response to a control signal S3 input from the control unit 131. In a power supply state in which power is supplied from the AC power source 2 to the load 3, the control unit 121 controls the switch unit 11 to be in an on state intermittently. When the bipolar transistor of the low impedance circuit 141 is conducted during a period in which the switch unit 11 is in an off state in the power supply state of the load 3, a charging path for the storage unit C1 is formed. For example, when the zero-cross detectors 191 and 192 detect a zero cross in each half cycle of the AC voltage Vac, the control unit 121 controls the bipolar transistor of the low impedance circuit 141 to a conductive state, and causes a charging current to flow to the power storage unit C1 via the low impedance circuit 141. Here, during the period in which the charging current flows to the power storage unit C1 via the low impedance circuit 141, it is assumed that the voltage applied across the switch unit 11 is lower than the peak voltage of the AC voltage Vac. Therefore, the low impedance circuit 141 is formed to have a lower impedance than the first power supply unit 13 so that the power storage unit C1 can be charged even when the voltage applied across the switch unit 11 is relatively small, and the power storage unit C1 can be charged in a short time via the low impedance circuit 141.

The charge detection unit 17 detects the charging state of the storage unit C1 by the second power supply unit 14. Specifically, the charge detection unit 17 is electrically connected to a series circuit of a Zener diode ZD2 and a resistor R1 connected to the output terminal of the low impedance circuit 141. The charge detection unit 17 is connected to the connection point between the Zener diode ZD2 and the resistor R1, and when the voltage VC1 across the storage unit C1 becomes equal to or higher than a threshold value (e.g., DC 10 V), the charge detection unit 17 detects that charging of the storage unit C1 is complete and outputs a detection signal S4 indicating completion of charging to the control unit 121. When the detection signal S4 indicating completion of charging is input from the charge detection unit 17, the control unit 12 controls the bipolar transistor of the low impedance circuit 141 to a cut-off state to cut off the charging path through which the charging current flows to the storage unit C1. When charging of the power storage unit C1 by the second power supply unit 14 is completed, the control unit 121 controls the switch unit 11 to a conductive state, and when, for example, a half cycle of the AC voltage is completed, the control unit 121 controls the switch unit 11 to a cut-off state.

The third power supply unit 15 generates power for operating the internal circuit 12 using the power storage unit C1 as a power source.

As described above, in this embodiment, in the cut-off state, the first power supply unit 13 charges the power storage unit C1, and in the power supply state, the second power supply unit 14 charges the power storage unit C1, and the charging voltage of the power storage unit C1 in the cut-off state is lower than the charging voltage of the power storage unit C1 in the power supply state. This makes it possible to prevent a large charging current from flowing into the power storage unit C1 via the first power supply unit 13 when switching from the power supply state to the cut-off state. Therefore, it is possible to suppress the leakage current flowing through the power supply circuit 20 when switching from the power supply state to the cut-off state, and to reduce the possibility of the load 3 (lighting load) switching from the on state to the off state temporarily erroneously lighting up.

It is preferable that the difference between the charging voltage of the storage unit C1 in the power supplying state and the charging voltage of the storage unit C1 in the cut-off state is 50% or less of the charging voltage of the storage unit C1 in the power supplying state, and this can prevent a large charging current from flowing into the storage unit C1 when the switch unit 11 is switched to the power supplying state or the cut-off state, and can prevent the operation of the load 3 from becoming unstable. It is more preferable that the difference between the charging voltage of the storage unit C1 in the power supplying state and the charging voltage of the storage unit C1 in the cut-off state is 30% or less of the charging voltage of the storage unit C1 in the power supplying state. This can further prevent a large charging current from flowing into the storage unit C1 when the switch unit 11 is switched to the power supplying state or the cut-off state. Furthermore, it is preferable that the charging voltage of the storage unit C1 in the power supplying state is equal to the charging voltage of the storage unit C1 in the cut-off state, so that a large charging current can be prevented from flowing into the storage unit C1 when the switch unit 11 is switched to the power supplying state or the cut-off state, and the operation of the load 3 can be prevented from becoming unstable. Here, the charging voltage of the storage unit C1 in the power supplying state and the charging voltage of the storage unit C1 in the cut-off state being equal does not necessarily mean that the two are exactly the same voltage, but may include a difference between the two being 5% or less of the charging voltage of the storage unit C1 in the power supplying state.

In this embodiment, a current limiting unit 16 that limits the current value of the current to a predetermined value or less is connected between the power storage unit C1 and the third power supply unit 15. The power storage unit C1 is connected to the primary side of the current limiting unit 16, and the capacitor C2 is connected to the secondary side of the current limiting unit 16. The current limiting unit 16 forms a charging path for the current flowing to the capacitor C2, that is, the charging current to the capacitor C2. Since the current limiting unit 16 limits the current flowing from the power storage unit C1 to the capacitor C2 to a predetermined value or less, even if the power consumption of the internal circuit 12 fluctuates, the change in the discharge current from the power storage unit C1 can be suppressed, and the change in the current flowing to the load 3 can be suppressed. The capacitor C2 on the secondary side functions as a buffer that absorbs the fluctuation in power consumption in the internal circuit 12. The voltage VC2 across the capacitor C2 is applied to the third power supply unit 15. In this embodiment, the current limiting unit 16 includes a constant current circuit 161, which controls the current to a constant value, thereby limiting the current to a predetermined value or less. However, the current limiting unit 16 is not limited to one that includes a constant current circuit 161, and may also include a current limiter circuit, etc.

A series circuit of a Zener diode ZD1 and a switch element Q3 is connected across the capacitor C2. The switch element Q3 is turned on/off by a control signal S5 input from the control unit 121. When the switch unit 11 is in a conductive state, the control unit 121 controls the switch element Q3 to an on state, and the Zener diode ZD1 is connected across the capacitor C2. When the switch element Q3 is controlled to an on state, a current flows through the Zener diode ZD1, so that the constant current control by the constant current circuit 161 is constantly operating.

The third power supply unit 15 includes a DC/DC converter 151, such as a step-down chopper. In the figure, the DC/DC converter 151 is simply denoted as "DC/DC". The DC/DC converter 151 converts the voltage across the capacitor C2 into an output voltage V2, which is a DC voltage of a predetermined voltage value (e.g., 3.3 V), and applies this output voltage V2 to the internal circuit 12. As a result, the third power supply unit 15 supplies power to the internal circuit 12 using the power storage unit C1, which is charged by either the first power supply unit 13 or the second power supply unit 14, as a power source.

The internal circuit 12 has a control unit 121, a wireless communication unit 122, and an operation reception unit 123. That is, in addition to the control unit 121, the internal circuit 12 further includes a wireless communication unit 122 that performs wireless communication. The power for operating the internal circuit 12 including the control unit 121, the wireless communication unit 122, and the operation reception unit 123 is generated by the third power supply unit 15. In other words, each of the control unit 121, the wireless communication unit 122, and the operation reception unit 123 included in the internal circuit 12 operates by receiving power supply from the third power supply unit 15.

The control unit 121 mainly comprises, for example, a microcontroller having one or more processors and one or more memories. The microcontroller realizes the function of the control unit 121 by executing a program recorded in one or more memories with one or more processors. The program may be recorded in the memory in advance, or may be provided recorded on a non-transitory recording medium such as a memory card, or provided through a telecommunications line. In other words, the above program is a program for causing one or more processors to function as the control unit 121.

The control unit 121 controls at least the switch unit 11 to be turned on and off. Furthermore, the control unit 121 may control the switch unit 11 (hereinafter also referred to as "load control") so as to adjust the amount of power supplied from the AC power source 2 to the load 3 per unit time by phase control (including reverse phase control) or PWM (Pulse Width Modulation) control. The control unit 121 also controls each component of the power supply circuit 20.

Specifically, as shown in FIG. 2, the control unit 121 acquires detection signals ZC1 and ZC2 representing the detection results from the zero-cross detection units 191 and 192, respectively. Similarly, the control unit 121 acquires a detection signal S4 representing the detection result from the charge detection unit 17. The control unit 121 also outputs a control signal S1 for controlling the switch unit 11 to the level shift circuit 18. The control unit 121 outputs a control signal S3 for controlling the low impedance circuit 141 to the low impedance circuit 141. The control unit 121 also outputs a control signal S5 for turning the switch element Q3 on and off to the switch element Q3. In this way, the control unit 121 appropriately acquires the detection signals ZC1, ZC2, and S4, and outputs the control signals S1, S3, and S5 to control the switch unit 11 and the power supply circuit 20.

The wireless communication unit 122 performs wireless communication using radio waves as a medium with other communication devices, either directly or indirectly via a repeater or the like. The communication between the wireless communication unit 122 and the communication devices is wireless communication conforming to a communication standard such as a specific low-power radio station (a radio station not requiring a license) in the 920 MHz band, Wi-Fi (registered trademark), or Bluetooth (registered trademark). Examples of other communication devices include a sensor terminal such as a human presence sensor, or a remote controller that accepts human operations. The wireless communication unit 122 communicates bidirectionally with these communication devices, enabling the control unit 121 to control the switch unit 11 based on a wireless signal from the communication device.

The operation reception unit 123 has a user interface such as a touch panel. The touch panel has a display function and a touch sensor function. This type of operation reception unit 123 can, for example, display information such as the operating status of the load control device 1 to present to a person, or output a signal in response to a human touch operation. The presence of such an operation reception unit 123 enables the control unit 121 to control the switch unit 11 based on a human operation on the operation reception unit 123.

(2.3) Operation of the Load Control Device First, immediately after the load control device 1 is started, that is, immediately after the power supply starts, the switch unit 11 is in an interrupted state, that is, the load 3 is in an off state, and the low impedance circuit 141 of the second power supply unit 14 is controlled to a state in which no current flows. As a result, in the power supply circuit 20, the first power supply unit 13 charges the storage unit C1. That is, the voltage applied to both ends of the switch unit 11 charges the capacitor C0 via the dropper power supply circuit 131, and the DC/DC converter 132 drops the voltage across the capacitor C0 to charge the storage unit C1. At this time, the constant current circuit 161 uses the storage unit C1 as a power source to pass a charging current to the capacitor C2, and the DC/DC converter 151 drops the voltage VC2 across the capacitor C2 to generate an output voltage V2 to be output to the internal circuit 12. As a result, the internal circuit 12 starts operating by receiving power from the power supply circuit 20.

After that, when the operation receiving unit 123 receives an operation input to turn on the load 3, the load control device 1 performs a lighting operation to turn on the load 3.

The lighting operation of the load control device 1 of this embodiment will now be described with reference to FIG. 2. FIG. 2 shows the AC voltage Vac, the load voltage V1 applied to the load 3, the detection signals ZC1 and ZC2 of the zero-cross detection units 191 and 192, and the control signal S2 input to the gate terminals of the MOSFETs Q1 and Q2. Here, the detection signal ZC1 is a detection signal by the zero-cross detection unit 191, and the detection signal ZC2 is a detection signal by the zero-cross detection unit 192. Note that here, it is assumed that the detection signals ZC1 and ZC2 are generated when the detection signals ZC1 and ZC2 change from the "H" level to the "L" level. In other words, the detection signals ZC1 and ZC2 are signals that change from the "H" level to the "L" level when a zero-cross point is detected.

First, the operation of the load control device 1 during a half cycle in which the AC voltage Vac is positive will be described. The load control device 1 detects the zero-crossing point of the AC voltage Vac using the zero-crossing detection unit 191. When the AC voltage Vac transitions from a negative half cycle to a positive half cycle, the zero-crossing detection unit 191 outputs a detection signal ZC1 when the AC voltage Vac reaches the positive specified value "Vzc". In this embodiment, the time point at which the detection signal ZC1 is generated is defined as the first time point t1, and the period from the start point (zero-crossing point) t0 of the half cycle to the first time point t1 is defined as the first period T1.

Here, during the first period T1 from the start point t0 of the half cycle to the first time point t1, the control unit 121 outputs a control signal S1 to the level shift circuit 18 to turn off the switch unit 11 (cut-off state). In response to this control signal S1, the level shift circuit 18 outputs an "OFF" signal as the control signal S2. As a result, during the first period T1, both of the two MOSFETs Q1 and Q2 are turned off, and the switch unit 11 is turned off.

When the detection signal ZC1 is input to the control unit 121 at the first time point t1, the control unit 121 outputs a control signal S3 to the low impedance circuit 141 to turn on the bipolar transistor of the low impedance circuit 141. As a result, the second power supply unit 14 charges the storage unit C1, and a charging current flows from the storage unit C1 to the capacitor C2 via the constant current circuit 161, charging the capacitor C2. Then, the DC/DC converter 151 reduces the voltage across the capacitor C2 to generate an output voltage V2 to be output to the internal circuit 12. Here, when the charge detection unit 17 detects the completion of charging the storage unit C1 and outputs a detection signal S4 to the control unit 121, the control unit 121 outputs a control signal S3 to the low impedance circuit 141 to turn off the bipolar transistor of the low impedance circuit 141, and stops charging the storage unit C1 by the second power supply unit 14. Then, the control unit 121 outputs a control signal S1 to turn on the switch unit 11. In response to this control signal S1, the level shift circuit 18 outputs an "ON" signal as the control signal S2. This switches the switch unit 11 from OFF to ON, and power is supplied from the AC power source 2 to the load 3.

After that, when the AC voltage Vac falls below the positive polarity specified value "Vzc" and the zero-cross detection unit 191 stops outputting the detection signal ZC1, the control unit 121 outputs a control signal S1 to the level shift circuit 18 to turn off the switch unit 11 (cut-off state). In response to this control signal S1, the level shift circuit 18 outputs an "OFF" signal as the control signal S2. As a result, both of the two MOSFETs Q1 and Q2 are turned off, and the switch unit 11 is turned off. Therefore, in the positive polarity half cycle of the AC voltage Vac, during the period T2 from the first time point t1 to the timing when the AC voltage Vac becomes less than the specified value Vzc, the switch unit 11 is turned on, power is supplied from the AC power source 2 to the load 3, and the load 3 is turned on.

In addition, the operation of the load control device 1 during a half cycle in which the AC voltage Vac is negative is basically the same as during a half cycle in which the AC voltage Vac is positive.

In the negative half cycle, when the AC voltage Vac reaches the negative specified value "-Vzc", the zero-cross detection unit 192 outputs the detection signal ZC2. In this embodiment, the period from the start point t0 (t2) of the negative half cycle to the first time point t1, which is the time point when the detection signal ZC2 is generated, is defined as the first period T1. When the detection signal ZC2 is input to the control unit 121 at the first time point t1, the control unit 121 outputs a control signal S3 to the low impedance circuit 141 to turn on the bipolar transistor of the low impedance circuit 141. As a result, the second power supply unit 14 charges the storage unit C1, and a charging current flows from the storage unit C1 to the capacitor C2 via the constant current circuit 161, charging the capacitor C2. Then, the DC/DC converter 151 steps down the voltage across the capacitor C2 to generate the output voltage V2 to be output to the internal circuit 12. Here, when the charge detection unit 17 detects the completion of charging of the power storage unit C1 and outputs a detection signal S4 to the control unit 121, the control unit 121 outputs a control signal S3 to the low impedance circuit 141 to turn off the bipolar transistor of the low impedance circuit 141, and stops charging the power storage unit C1 by the second power supply unit 14. Then, the control unit 121 outputs a control signal S1 to turn on the switch unit 11. The level shift circuit 18 outputs an "ON" signal as the control signal S2 in response to this control signal S1. This switches the switch unit 11 from off to on, and power is supplied from the AC power source 2 to the load 3.

After that, when the AC voltage Vac exceeds the negative polarity specified value "-Vzc" and the zero-cross detection unit 192 stops outputting the detection signal ZC2, the control unit 121 outputs a control signal S1 to the level shift circuit 18 to turn off the switch unit 11 (cut-off state). The level shift circuit 18 outputs an "OFF" signal as the control signal S2 in response to this control signal S1. As a result, both of the two MOSFETs Q1 and Q2 are turned off, and the switch unit 11 is turned off. Therefore, in the negative polarity half cycle of the AC voltage Vac, during the period T2 from the first time point t1 to the timing when the AC voltage Vac exceeds the specified value (-Vzc), the switch unit 11 is turned on, power is supplied from the AC power source 2 to the load 3, and the load 3 is turned on.

The load control device 1 of this embodiment lights up the load 3 by alternately repeating the above-described positive half-cycle operation and negative half-cycle operation every half cycle of the AC voltage Vac. Note that if the positive polarity specified value "Vzc" and the negative polarity specified value "-Vzc" are fixed values, the time from the start point t0 of the half cycle to the first point in time (the point in time when the detection signal ZC1 or ZC2 is generated) t1 will be a time of approximately fixed length.

After that, when the operation reception unit 123 receives an operation to turn off the load 3, the control unit 121 controls the switch unit 11 to the cut-off state. When the switch unit 11 is in the cut-off state, the charging path via the low impedance circuit 141 is cut off and the storage unit C1 is charged by the first power supply unit 13. In this embodiment, the charging voltage of the storage unit C1 in the cut-off state is lower than the charging voltage of the storage unit C1 in the power supply state. This prevents a large charging current from flowing through the storage unit C1 via the first power supply unit 13 when switching from the power supply state to the cut-off state, so that a large current does not flow through the load 3 in the off state, and the possibility of the load 3 in the off state being erroneously turned on can be reduced.

When the operation receiving unit 123 receives an operation input for turning on the load 3 at a desired dimming level, the load control device 1 may perform dimming control to adjust the brightness of the load 3, which is a lighting load, by controlling the conduction period of the switch unit 11 according to the dimming level.

First, we will explain the operation of the load control device 1 during a half cycle in which the AC voltage Vac is positive.

During a first period T1 from the start point t0 of the positive polarity half cycle to a first time point t1 at which the zero-cross detection unit 191 generates a detection signal ZC1, the control unit 121 controls the switch unit 11 to be turned off. When the detection signal ZC1 is input to the control unit 121 at the first time point t1, the control unit 121 switches the switch unit 11 from off to on to supply power from the AC power source 2 to the load 3. In addition, at a second time point at which a conduction period (second period) of a length corresponding to the dimming level has elapsed from the timing at which the switch unit 11 was switched on, the control unit 121 switches the switch unit 11 from on to off to cut off the supply of power from the AC power source 2 to the load 3. When the control unit 121 controls the switch unit 11 to be turned off at the second time point, the switch unit 11 is maintained in a cut-off state until the zero-cross detection unit 192 detects the start point of a negative polarity half cycle of the AC voltage Vac.

In addition, the operation of the load control device 1 during a half cycle in which the AC voltage Vac is negative is basically the same as during a half cycle in which the AC voltage Vac is positive.

During a first period T1 from the start point t0 of the negative half cycle to the first time point t1 at which the zero-cross detection unit 192 generates the detection signal ZC2, the control unit 121 controls the switch unit 11 to be turned off. When the detection signal ZC2 is input to the control unit 121 at the first time point t1, the control unit 121 switches the switch unit 11 from off to on to supply power from the AC power source 2 to the load 3. In addition, at a second time point at which a conduction period of a length corresponding to the dimming level has elapsed since the timing at which the switch unit 11 was switched on, the control unit 121 switches the switch unit 11 from on to off to cut off the supply of power from the AC power source 2 to the load 3. When the control unit 121 controls the switch unit 11 to be turned off at the second time point, the switch unit 11 is maintained in a cut-off state until the zero-cross detection unit 191 detects the start point of the positive half cycle of the AC voltage Vac.

The load control device 1 alternates between a positive half-cycle operation of the AC voltage Vac and a negative half-cycle operation, thereby turning on the switch unit 11 for a conduction period corresponding to the dimming level during each half-cycle of the AC voltage Vac, thereby dimming the load 3.

In the load control device 1 of this embodiment, the internal circuit 12 includes a wireless communication unit 122, which consumes a large amount of power when transmitting or receiving a wireless signal, so that the power consumption of the internal circuit 12 may increase temporarily. Here, since the second buffer storage unit C2 is connected to the front stage of the third power supply unit 15, the discharge current of the second storage unit C2 can compensate for the temporary increase in power consumption in the internal circuit 12, and the input current from the connection terminals TA1 and TA2 to the power supply circuit 20 can be suppressed from increasing. Therefore, even if the power consumption of the internal circuit 12 increases temporarily, the fluctuation of the current flowing through the load 3 can be suppressed, and the possibility of the operation of the load 3 becoming unstable can be reduced. Note that, when the internal circuit 12 includes a circuit with a relatively large power consumption, such as the wireless communication unit 122, it is preferable to use a relatively large-capacity capacitor as the second buffer storage unit C2 in the front stage of the third power supply unit 15.

The load 3 of the load control device 1 of this embodiment includes a dimmable lighting load. When dimming the load 3, the control unit 121 controls the switch unit 11 to be on (conductive state) during a conduction period determined according to the dimming level of the lighting load during each half cycle of the AC voltage Vac of the AC power source 2, and controls the switch unit 11 to be off (cut-off state) during a cut-off period other than the conduction period. This allows the load control device 1 to adjust the power supplied to the load 3 according to the dimming level of the load 3, and to dim the load 3.

The control unit 121 controls the switch unit 11 to the on state (conducting state) from the start of a half cycle of the AC voltage Vac until the conduction period has elapsed, and controls the switch unit 11 to the off state (blocking state) after the conduction period has elapsed. The control unit 121 switches the switch unit 11 from the blocking state to the conducting state when the voltage value of the AC voltage Vac is relatively low, thereby reducing the possibility of a surge voltage occurring when the switch unit 11 switches from the blocking state to the conducting state.

(3) Modifications The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. For example, the specific circuit shown in FIG. 1 is merely one example of the load control device 1 of the present disclosure, and various modifications can be made depending on the design, etc. Each figure described in the present disclosure is a schematic diagram, and the ratio of the size and thickness of each component in each figure does not necessarily reflect the actual dimensional ratio. In addition, the function equivalent to the control unit 121 of the load control device 1 according to the above embodiment may be embodied in a control method, a (computer) program, or a non-transitory recording medium on which a program is recorded, etc.

The load control device 1 in the present disclosure also includes a computer system in the control unit 121, etc. The computer system is mainly composed of a processor and a memory as hardware. The function of the load control device 1 in the present disclosure is realized by the processor executing a program recorded in the memory of the computer system. The program may be pre-recorded in the memory of the computer system, may be provided through an electric communication line, or may be recorded and provided in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits such as IC or LSI referred to here are called differently depending on the degree of integration, and include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, a field-programmable gate array (FPGA) that is programmed after the manufacture of the LSI, or a logic device that can reconfigure the connection relationship inside the LSI or reconfigure the circuit partition inside the LSI, can also be adopted as a processor. The multiple electronic circuits may be integrated into one chip, or may be distributed across multiple chips. The multiple chips may be integrated into one device, or may be distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

In addition, it is not essential for the load control device 1 that at least some of the functions of the load control device 1 are concentrated in one housing, and the components of the load control device 1 may be distributed across multiple housings. For example, the operation reception unit 123 may be provided in a housing separate from the control unit 121. In addition, at least some of the functions of the control unit 121, etc. may be realized, for example, by a server or a cloud (cloud computing), etc.

In addition, for example, a switching power supply circuit may be used instead of the dropper power supply circuit 131, or the dropper power supply circuit 131 may be omitted, and other appropriate changes to the circuit design are possible.

In the above embodiment, the control unit 121 controls switching between a power supply state in which power is supplied to the load 3 and a cut-off state in which power supply to the load 3 is cut off, but the power supplied to the load 3 may be adjusted by phase controlling the switch unit 11. In the above embodiment, when the control unit 121 controls the phase of the switch unit 11, the control unit 121 controls the switch unit 11 in reverse phase, but the control unit 121 may also control the switch unit 11 in forward phase. In other words, the control unit 121 may control the switch unit 11 to the off state from the start of a half cycle of the AC voltage Vac until the cut-off period has elapsed, and control the switch unit 11 to the on state after the cut-off period has elapsed.

In the above embodiment, the AC power source 2 is a single-phase 100 V, 60 Hz commercial power source, but it may be a single-phase 100 V, 50 Hz commercial power source. The voltage value of the AC power source 2 is not limited to 100 V.

In the above embodiment, the load control device 1 is a single-pole switch, but other configurations are also possible. For example, the load control device 1 may be a so-called three-way switch that can connect three wires. The load control device 1 may be a so-called four-way switch that can connect four wires. When the load control device 1 constitutes a three-way switch, by combining two load control devices 1, it is possible to switch the power supply state to the load 3 at two locations, for example, the upper and lower parts of a staircase in a building.

In the above embodiment, the zero-cross detection unit 191 is configured to detect a zero cross when the switch voltage switches from negative to positive when the voltage between the connection terminal TA1 and ground becomes equal to or greater than a reference value, but the opposite is also possible. In other words, the zero-cross detection unit 191 may be configured to detect a zero cross when the switch voltage switches from positive to negative when the voltage between the connection terminal TA1 and ground becomes less than a reference value. Similarly, the zero-cross detection unit 192 is configured to detect a zero cross when the switch voltage switches from positive to negative when the voltage between the connection terminal TA2 and ground becomes equal to or greater than a reference value, but the opposite is also possible. In other words, the zero-cross detection unit 192 may be configured to detect a zero cross when the switch voltage switches from negative to positive when the voltage between the connection terminal TA2 and ground becomes less than a reference value.

The load 3 is not limited to a lighting device having a light source made of an LED, but may be a lighting device having a light source other than an LED. Furthermore, the load 3 is not limited to a lighting load, but may be, for example, a device (including a device, system, and equipment) such as a ventilation fan, a display device, an electric shutter, an air conditioner, or a security device. The load 3 is not limited to a single device, but may be multiple devices electrically connected in series or parallel.

The load control device 1 may further include an operation terminal for connecting a child device. The child device includes a contact portion such as a push button switch, and the on/off of the contact portion is detected by the load control device 1. In this case, the load control device 1 controls the switch portion 11 so as to switch the operating state of the switch portion 11 according to the operation of the child device (on/off of the contact portion). That is, the load control device 1 operates so that the switch portion 11 switches between a cut-off state and a conductive state every time the push button switch is pressed in the child device to turn on the contact portion. In short, in the load control device 1, the control of the switch portion 11 may be performed not only according to the output of the wireless communication portion 122 and the operation reception portion 123, but also according to the operation of the child device. Therefore, the load control device 1 and the child device are installed separately in two places, for example, the upper floor and lower floor of a staircase in a building, so that the power supply state to the load 3 can be switched at two places.

The internal circuit 12 may also include a sensor circuit, a timer circuit, or the like, in addition to or instead of the wireless communication unit 122 and the operation reception unit 123. As an example, the sensor circuit includes a human presence sensor and/or a brightness sensor that detects whether or not a person is present. The load control device 1 can control the switch unit 11 based on the output of these sensor circuits or timer circuits.

In the above embodiment, the switch unit 11 has two MOSFETs Q1 and Q2, but it is not limited to MOSFETs and may be other semiconductor switches. For example, the switch unit 11 may be realized by a three-terminal bidirectional thyristor (triac), or may be realized by a semiconductor element with a double gate (dual gate) structure using a wide band gap semiconductor material such as GaN (gallium nitride).

(summary)
As described above, the load control device (1) of the first aspect includes a pair of connection terminals (TA1, TA2), a switch unit (11), an internal circuit (12), a power storage unit (C1) for supplying power to the internal circuit (12), a first power supply unit (13), and a second power supply unit (14). The pair of connection terminals (TA1, TA2) are connected to a series circuit of an AC power source (2) and a load (3). The switch unit (11) is connected between the pair of connection terminals (TA1, TA2). The internal circuit (12) includes at least a control unit (121) that controls the on/off of the switch unit (11). The first power supply unit (13) includes a DC/DC converter (132) connected between the pair of connection terminals (TA1, TA2) and the power storage unit (C1). The first power supply unit (13) charges the power storage unit (C1) by applying the output voltage of the DC/DC converter (132) to the power storage unit (C1) in a cut-off state in which power supply from the AC power source (2) to the load (3) is cut off. The second power supply unit (14) charges the power storage unit (C1) by forming a charging path with lower impedance than that of the first power supply unit (13) between a pair of connection terminals (TA1, TA2) and the power storage unit (C1) in a power supply state in which power is supplied from the AC power source (2) to the load (3).

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the load control device (1) of the second embodiment, the charging voltage of the storage unit (C1) in the cut-off state is lower than the charging voltage of the storage unit (C1) in the power supply state in the first embodiment.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the load control device (1) of the third aspect, in the first aspect, the difference between the charging voltage of the storage unit (C1) in the power supply state and the charging voltage of the storage unit (C1) in the cut-off state is 50% or less of the charging voltage of the storage unit (C1) in the power supply state.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the load control device (1) of the fourth aspect, in the first aspect, the charging voltage of the storage unit (C1) in the power supply state is equal to the charging voltage of the storage unit (C1) in the cut-off state.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

The load control device (1) of the fifth aspect, in any one of the first to fourth aspects, further includes a third power supply unit (15) that converts the voltage across the storage unit (C1) to generate power for operating the internal circuit (12).

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the sixth embodiment of the load control device (1), a current limiting unit (16) that limits the current value to a predetermined value or less is connected between the power storage unit (C1) and the third power supply unit (15) in the fifth embodiment.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the seventh aspect of the load control device (1), the current limiting unit (16) in the sixth aspect includes a constant current circuit (161).

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the eighth aspect of the load control device (1), in the sixth or seventh aspect, the storage unit (C1) is the first storage unit (C1). The second storage unit (C2) is connected between the third power supply unit (15) and the current limiting unit (16).

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the load control device (1) of the ninth aspect, in any one of the first to eighth aspects, the internal circuit (12) further includes a wireless communication unit (122) that performs wireless communication.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the load control device (1) of the tenth aspect, in any one of the first to ninth aspects, the load (3) includes a dimmable lighting load (3). The control unit (121) controls the switch unit (11) to be on during a conduction period determined according to the dimming level of the lighting load (3) during each half cycle of the AC voltage (Vac) of the AC power source (2), and controls the switch unit (11) to be off during a cut-off period other than the conduction period.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

In the load control device (1) of the eleventh aspect, in the tenth aspect, the control unit (121) controls the switch unit (11) to be in the on state from the start of a half cycle of the AC voltage (Vac) until the conduction period has elapsed, and controls the switch unit (11) to be in the off state after the conduction period has elapsed.

According to this embodiment, it is possible to prevent the operation of the load (3) from becoming unstable when switching from a power supply state to a power cut-off state.

Not limited to the above aspects, various configurations (including modified examples) of the load control device (1) according to the above embodiment can be embodied as a control method for the load control device (1), a (computer) program, or a non-transitory recording medium on which a program is recorded, etc.

The configurations according to the second to eleventh aspects are not essential for the load control device (1) and may be omitted as appropriate.

1 Load control device 2 AC power supply 3 Load (lighting load)
REFERENCE SIGNS LIST 11 Switch section 12 Internal circuit 13 First power supply section 14 Second power supply section 15 Third power supply section 16 Current limiting section 132 DC/DC converter 161 Constant current circuit C1 Power storage section (first power storage section)
C2 Second storage unit TA1, TA2 Connection terminal Vac AC voltage

Claims (8)

A pair of connection terminals to which a series circuit of an AC power source and a load is connected;
a switch portion connected between the pair of connection terminals;
an internal circuit including at least a control unit for controlling the on/off of the switch unit;
a power storage unit for supplying power to the internal circuit;
a first power supply unit including a DC/DC converter connected between the pair of connection terminals and the power storage unit, the first power supply unit applying an output voltage of the DC/DC converter to the power storage unit in a cut-off state in which power supply from the AC power source to the load is cut off, thereby charging the power storage unit;
a second power supply unit that, in a power supply state in which power is supplied from the AC power source to the load, forms a charging path having a lower impedance than that of the first power supply unit between the pair of connection terminals and the power storage unit, and charges the power storage unit;
a third power supply unit that converts a voltage between both ends of the power storage unit to generate power for operating the internal circuit,
a current limiting unit that limits a current value to a predetermined value or less is connected between the power storage unit and the third power supply unit,
the power storage unit is a first power storage unit,
a second power storage unit is connected between the third power supply unit and the current limiting unit,
a series circuit including a Zener diode and a switch element connected between both ends of the second power storage unit,
The control unit controls the switch element to be in a conductive state when the switch unit is in a conductive state.
Load control device. a charging voltage of the power storage unit in the power supplying state is lower than a charging voltage of the power storage unit in the power interrupted state;
The load control device according to claim 1 . a difference between a charging voltage of the power storage unit in the power supplying state and a charging voltage of the power storage unit in the power cut-off state is 50% or less of the charging voltage of the power storage unit in the power supplying state;
The load control device according to claim 1 . A charging voltage of the power storage unit in the power supplying state is equal to a charging voltage of the power storage unit in the power cut-off state.
The load control device according to claim 1 . The current limiting unit includes a constant current circuit.
The load control device according to any one of claims 1 to 4. The internal circuit further includes a wireless communication unit for performing wireless communication.
The load control device according to any one of claims 1 to 5. the load comprises a dimmable lighting load;
The control unit controls the switch unit to be on during a conduction period determined according to a dimming level of the lighting load during each half cycle of the AC voltage of the AC power supply, and controls the switch unit to be off during a cut-off period other than the conduction period.
The load control device according to any one of claims 1 to 6. the control unit controls the switch unit to an on state from a start point of a half cycle of the AC voltage until the conduction period has elapsed, and controls the switch unit to an off state after the conduction period has elapsed.
The load control device according to claim 7.

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