TW202207593A - Load control device - Google Patents

Abstract

The purpose of the present disclosure is to provide a low-loss load control device that can reduce noise. In the present invention, a first switch (SW1) is connected between a pair of connecting terminals (TA1, TA2), and switches to one of an off state in which the supply of electric power from an AC power source (2) to a load (3) is shut down and an on state in which electric power is supplied from the AC power source (2) to the load (3). A second switch (SW2) is inserted into current paths (RT1, RT2) through which current flows from the AC power source (2) to a capacitive element (12) via at least one of the pair of connecting terminals (TA1, TA2). In each half cycle of an AC voltage (Vac) of the AC power source (2), a control unit (11) controls the first switch (SW1) to the on state during a conduction period determined according to the electric power supplied to the load (3), and controls the first switch (SW1) to the off state during a shutdown period other than the conduction period. The control unit (11) controls the second switch (SW2) to the on state at a switching timing at which the first switch (SW1) is switched on/off partway through each half cycle of the AC voltage (Vac).

Description

load control device

The present invention relates to a load control device. Specifically, the present invention relates to a load control device for controlling electric power supplied to a load.

The dimming device disclosed in Patent Document 1 includes a switch unit connected in series to a load with respect to an AC power source, and a control unit. The control unit controls the phase of the AC voltage supplied to the load by controlling on/off of the switch unit.

In the dimming device of Patent Document 1, so-called reverse phase control is performed, and the switching unit is turned on at the time of the zero-crossing of the AC voltage, and the switching unit is turned on in the middle of each half cycle of the AC voltage. Disconnect to interrupt the power supply to the load.

In the above-mentioned Patent Document 1, when the switch part is turned off, the inductance (hereinafter, referred to as system inductance) of the wire connecting the AC power supply and the load and the switch part may cause a reverse voltage. If the turn-off speed of the switch portion is reduced, the reverse voltage generated during turn-off can be reduced, but there is a problem that the switching loss increases. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2013-149498

An object of the present invention is to provide a low-loss load control device capable of reducing noise.

A load control device according to an aspect of the present invention includes: a pair of connection terminals; a first switch; a capacitive element; a second switch; and a control unit. A series circuit of an AC power source and a load is connected to the pair of connection terminals. The first switch is connected between the pair of connection terminals, and is switched to either an OFF state for blocking the power supplied from the AC power source to the load, and an ON state for supplying power from the AC power source to the load By. The aforementioned second switch is inserted into the current path. The current path is a path through which current flows from the AC power source to the capacitive element via at least one of the pair of connection terminals. The control unit controls the first switch to be in an ON state during each half cycle of the AC voltage of the AC power supply during an ON period determined in accordance with the power supplied to the load, and during an OFF period other than the ON period , the first switch is controlled to be in an off state, and the control unit controls the second switch to be in the middle of each half cycle of the AC voltage at the switching time point of the on/off switching of the first switch. On state.

(implementation type 1) (1) Overview Hereinafter, the outline of the load control device 1 according to the first embodiment will be described with reference to FIG. 1 .

As shown in FIG. 1 , the load control device 1 of the present embodiment includes a pair of connection terminals TA1 and TA2 ; a first switch SW1 ; a capacitive element 12 ; a second switch SW2 ; and a control unit 11 .

A series circuit of the AC power source 2 and the load 3 is connected to the pair of connection terminals TA1 and TA2.

The first switch SW1 is connected between the pair of connection terminals TA1 and TA2. The first switch SW1 is switched to either an OFF state in which the power supplied from the AC power source 2 to the load 3 is interrupted, and an ON state in which the power supplied from the AC power source 2 to the load 3 is turned on.

The second switch SW2 is inserted into the current paths RT1 and RT2. The current paths RT1 and RT2 are paths through which current flows from the AC power source 2 to the capacitive element 12 via at least one of the pair of connection terminals TA1 and TA2 .

The control unit 11 controls the first switch SW1 to be in the ON state during each half cycle of the AC voltage Vac of the AC power source 2 during the ON period determined according to the power supplied to the load 3, and during the OFF period other than the ON period, The first switch SW1 is controlled to be turned off. The control unit 11 controls the second switch SW2 to be in the ON state at the switching timing of the ON/OFF switching of the first switch SW1 in the middle of each half cycle of the AC voltage Vac.

Among them, the first switch SW1 is realized by, for example, a semiconductor switch such as a transformer or a bidirectional thyristor. In the present embodiment, the load control device 1 is a so-called electronic switch, and by electronically controlling the first switch SW1, conduction/non-conduction between the AC power source 2 and the load 3 is electronically switched. The load control device 1 includes a pair of connection terminals TA1 and TA2, and the first switch SW1 is electrically connected between the pair of connection terminals TA1 and TA2. In other words, inside the load control device 1, the connection terminal TA1 and the connection terminal TA2 are electrically connected via the first switch SW1. One connection terminal TA1 is connected to the AC power source 2 , and the other connection terminal TA2 is connected to the load 3 , whereby the first switch SW1 is connected between the AC power source 2 and the load 3 .

In addition, the second switch SW2 is realized by, for example, a semiconductor switch such as a transformer or a bidirectional thyristor. The second switch SW2 is inserted into the above-described current paths RT1 and RT2. The load control device 1 is a so-called electronic switch, and by electronically controlling the second switch SW2, the state in which the current flows to the capacitive element 12 via the current paths RT1 and RT2 is electronically switched, and the current paths RT1 and RT2 are blocked. status. When the second switch SW2 is controlled to be in the ON state, current flows to the capacitive element 12 via the current paths RT1 and RT2, and when the second switch SW2 is controlled to be OFF, the current flows to the current paths RT1, RT2 of the capacitive element 12. RT2 will be blocked.

The capacitive element 12 is a chargeable and dischargeable element, and in this embodiment, is, for example, a capacitor. In addition, the capacitive element 12 is not limited to a capacitor, and may be an electric double layer capacitor or a secondary battery or the like.

The control unit 11 controls the first switch SW1 to be in the ON state during the ON period determined according to the power supplied to the load 3 in each half cycle of the AC voltage Vac, so that the supply power corresponding to the ON period can be supplied to the load 3 . However, at the switching timing in the middle of each half cycle of the AC voltage Vac, when the first switch SW1 is switched on/off, the circuit to which the first switch SW1 is connected (the AC power source 2 and the load 3 and the load control device are connected) 1 circuit, etc.) inductance (hereinafter, referred to as system inductance), etc., may cause reverse voltage to be generated. In the load control device 1 of the present embodiment, by turning on the second switch SW2 at the above-mentioned switching timing, the reverse voltage generated by the on/off switching of the first switch SW1 can be caused by the capacitive element 12 absorbs and reduces the noise generated by the load control device 1 . Therefore, in the load control device 1 of the present embodiment, in order to reduce noise, it is not necessary to set the turn-off speed or turn-on speed of the first switch SW1 to a low speed, the loss in the first switch SW1 can be reduced, and the first switch SW1 can be suppressed. 1 Heat of switch SW1. Furthermore, when the second switch SW2 is turned off, the current paths RT1 and RT2 through which the current flows from the AC power source 2 to the capacitive element 12 are blocked, so that unnecessary current can be suppressed from flowing to the load 3 .

(2) Details (2.1) Premise In this embodiment, the load control apparatus 1 is fixed to the installation object of a building. The "installation object" referred to in the present invention is an object to which the load control device 1 is fixed, and includes, for example, architectural facilities such as walls, ceilings, or floors of buildings, or daily utensils (including doors and windows) such as desks, shelves, or counters. The building in which the load control device 1 is installed is, for example, a residential facility such as a single-family house or an apartment complex, or a non-residential facility such as an office, a shop, a school, a factory, a hospital, or a long-term care facility.

In the present embodiment, as an example, the load control device 1 is assumed to be a built-in wiring device to be attached to an installation object constituted by a wall of a house. In addition, the AC power supply 2 is assumed to be, for example, a single-phase 100 [V], 60 [Hz] commercial AC power supply (system power supply). Further, the load 3 includes, for example, a dimmable lighting load. In the present embodiment, the load 3 is assumed to be a lighting device (lighting fixture) including a light source composed of LEDs (Light Emitting Diode) and a lighting circuit for lighting the light source. In the load 3 , when power is supplied from the AC power source 2 , the light source is turned on, and the light output changes according to the magnitude of the power supplied from the AC power source 2 .

In addition, the load control device 1 includes connection terminals TA1 and TA2 for connecting electric wires. For example, an electric wire wound in a wall portion (an installation object) is connected to the connection terminals TA1 and TA2, thereby being electrically connected to the AC via the electric wire. Power 2 and Load 3. The electric wire may be directly connected to the AC power supply 2 (system power supply, etc.), or may be indirectly connected via a distribution board or the like.

In addition, "terminals" such as connection terminals TA1 and TA2 in the present invention may not be components for connecting wires or the like, but may be, for example, reeds of electronic components or part of conductors included in a circuit board.

In addition, in the present invention, when comparing two values, the term "above" includes both the case where the two values are equal and the case where one of the two values exceeds the other. However, it is not limited to this, and "above" here may be equivalent to "greater than" when one of only two values exceeds the other. In other words, whether or not the two values are equal can be arbitrarily changed according to the setting of the reference value, etc., so there is no technical difference between "above" or "greater than". Likewise, "not up to" can also be equated with "below."

(2.2) Overall configuration of the load control device Hereinafter, the overall configuration of the load control device 1 of the present embodiment will be described with reference to FIG. 1 .

As shown in FIG. 1 , the load control device 1 of the present embodiment includes the pair of connection terminals TA1 and TA2 described above; a first switch SW1 ; a capacitive element 12 ; a second switch SW2 ; and a control unit 11 . In addition, the load control device 1 of the present embodiment further includes: zero-cross (indicated as "ZC" in the figure) detection units 15 and 16; a first drive circuit 17; a second drive circuit 18; a power supply unit 19; Section 20. These components of the load control device 1 are accommodated in one housing.

Each of the pair of connection terminals TA1 and TA2 is a component that is electrically and mechanically connected by electric wires. Each of the pair of connection terminals TA1 and TA2 is, as an example, a so-called quick-connect terminal of a wire differential type to which the wire is connected by inserting the wire from the terminal hole.

The first switch SW1 is inserted between the AC power source 2 and the load 3 , and switches between the ON state and the OFF state between the AC power source 2 and the load 3 . The term "insertion" in the present invention refers to being inserted between the two electrically connected, and the first switch SW1 is electrically connected between the AC power source 2 and the load 3 in the circuit formed by 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 first switch SW1.

In this embodiment, as an example, the first switch SW1 has two MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistor/Metal-Oxide-Semiconductor Field Effect Transistor) electrically connected in series between the pair of connection terminals TA1 and TA2. Q11, Q12. Each of the two MOSFETs Q11 and Q12 is an enhancement-type n-channel MOSFET. The two MOSFETs Q11 and Q12 are connected to each other through source terminals, that is, so-called inverse series connection, and switch on/off for current in both directions.

The gate terminals of the MOSFETs Q11 and Q12 are electrically connected to the first drive circuit 17 . The first drive circuit 17 outputs the control signals Sa1 and Sa2 to the gate terminals of the MOSFETs Q11 and Q12 by inputting the control signal from the control unit 11 , and drives the MOSFETs Q11 and Q12 .

In addition, as described above, the first switch SW1 includes the ON state and the OFF state as operating states. Among them, the ON state includes the ON state in the ON period determined by the control unit 11 in each half cycle of the AC voltage Vac, that is, the intermittent ON state. That is, in the present embodiment, the ON state of the first switch SW1 refers to a state in which power is supplied from the AC power supply 2 to the load 3 , and the OFF state of the first switch SW1 means that the supply of power from the AC power supply 2 to the load 3 is blocked. The state of power supply.

Here, it is assumed that the first switch SW1 is in a non-conductive state (off state), and the AC voltage Vac is applied from the AC power supply 2 between both ends of the first switch SW1 . That is, when the first switch SW1 is turned off, the voltage applied between both ends of the first switch SW1 (hereinafter, also referred to as “inter-switch voltage”) is approximately equal to the AC voltage from the AC power supply 2 Vac. Hereinafter, the polarity of the voltage between switches at which the connection terminal TA1 becomes a high potential is referred to as “positive polarity”, and the polarity of the voltage between switches at which the connection terminal TA2 becomes a high potential is referred to as “negative polarity”.

The zero-cross detection units 15 and 16 are configured to detect the zero-cross point of the voltage between the switches by detecting the magnitude of the voltage between the switches.

The zero-cross detection unit 15 is electrically connected to the connection terminal TA1. The zero-cross detection unit 15 compares the absolute value of the voltage between the connection terminal TA1 and the ground (reference potential point) with a reference value (for example, 10 [V]) to detect when the voltage between the switches is switched from negative polarity to positive polarity. zero crossing point. That is, when the zero-cross detection unit 15 detects that the positive-polarity inter-switch voltage has moved from a state of not reaching the reference value to a state of not exceeding the reference value, the zero-cross point is determined.

The zero-cross detection unit 16 is electrically connected to the connection terminal TA2. The zero-cross detection unit 16 detects zero when the voltage between the switches is switched from positive to negative by comparing the absolute value of the voltage between the terminal TA2 and the ground (reference potential point) with a reference value (for example, 10 [V]). intersection. That is, when the zero-cross detection unit 16 detects that the negative-polarity inter-switch voltage has moved from a state of not reaching a reference value to a state of being greater than or equal to the reference value, it is determined as a zero-cross point.

Therefore, the detection timing of the zero-cross point detected by the zero-cross detection units 15 and 16 is slightly delayed from the zero-cross point (0[V]), strictly speaking.

The power supply unit 19 generates electric power for operating circuits such as the control unit 11 from the voltage applied to both ends of the first switch SW1. The power supply unit 19 is electrically connected to the connection terminal TA1 via the diode D1, and is electrically connected to the connection terminal TA2 via the diode D2. Among them, a rectifier circuit DB1 is formed by the diodes D1, D2, and the body diodes D11, D12 of the MOSFETs Q11, Q12, and the AC voltage Vac from the AC power source 2 is full-wave rectified by the rectifier circuit DB1. The DC voltage is input to the Power supply unit 19 . The power supply unit 19 includes a voltage conversion circuit such as a series regulator, a buck chopper circuit, a buck-boost chopper circuit, or a booster chopper circuit, and smoothes the output voltage from the rectifier circuit DB1, thereby converting the constant voltage to a constant voltage. The DC voltage is supplied to circuits such as the control unit 11 .

Moreover, in the present embodiment, the capacitive element 12 and the second switch SW2 are connected in series between the connection terminal TA1 and the connection terminal TA2. In other words, a series circuit of the second switch SW2 and the capacitive element 12 is connected in parallel with the first switch SW1.

The capacitive element 12 is connected between the connection terminal TA1 and the second switch SW2. In the present embodiment, the capacitive element 12 is, for example, a single capacitor, but may be a plurality of capacitors connected in series or in parallel.

In the present embodiment, as an example, the second switch SW2 has two MOSFETs Q21 and Q22 electrically connected in series between the capacitive element 12 and the connection terminal TA2. Each of the two MOSFETs Q21 and Q22 is an enhancement-type n-channel MOSFET. The two MOSFETs Q21 and Q22 are connected to each other through source terminals, that is, so-called inverse series connection, and currents in both directions are switched on/off.

The gate terminals of the MOSFETs Q21 and Q22 are electrically connected to the second drive circuit 18 . The second drive circuit 18 outputs the control signals Sb1 and Sb2 to the gate terminals of the MOSFETs Q21 and Q22 by inputting the control signal from the control unit 11, and drives the MOSFETs Q21 and Q22.

The operation accepting unit 20 is, for example, a touch panel having a display function and a touch sensor function. Such a touch panel functions as a user interface. For example, the touch panel can remind the user by displaying information such as the operation status of the load control device 1, or accept the touch operation of the user for changing the operation of the load control device 1, and then output the operation signal to the control unit 11. In the present embodiment, the operation accepting unit 20 accepts, for example, an operation of switching the lighting and extinguishing of the load 3 or an operation of switching the dimming level of the load 3 , and outputs an operation signal to the control unit 11 . The control unit 11 controls the first switch SW1 based on the operation signal input from the operation accepting unit 20 . In addition, the operation accepting unit 20 is not limited to those having a touch panel, and may be a mechanical switch for accepting an operation by a user, or a device such as a variable resistor with a switch.

In addition, the operation accepting unit 20 can receive the control command from a transmitter that transmits a wireless signal including a control command of the load 3 in accordance with the user's operation, and output the control command as an operation signal to the control unit 11 . Such wireless communication is, for example, a specific low-power radio station with a bandwidth of 920 MHz (a radio station that does not require a license), Wi-Fi (registered trademark), or wireless communication based on communication standards such as Bluetooth (registered trademark). The operation accepting unit 20 having the wireless communication unit can receive wireless communication from the transmitter by performing wireless communication with the transmitter, and the control unit 11 can control the first switch SW1 based on the wireless signal from the transmitter.

The control unit 11 includes, for example, a microcontroller having one or more processors and one or more memories as a main configuration. The microcontroller implements a function as the control unit 11 by executing a program recorded in one or more memories by one or more processors. The program may be pre-recorded in the memory, or may be recorded in a temporary recording medium such as a memory card and then provided, or provided via a telecommunication line. In other words, the above-mentioned program is a program for making one or more processors function as the control unit 11 .

The control unit 11 performs ON/OFF control of at least the first switch SW1 and the second switch SW2. Specifically, as shown in FIG. 2 , the control unit 11 acquires detection signals ZC1 and ZC2 respectively indicating the detection results from the zero-cross detection units 15 and 16 . Moreover, the control part 11 acquires the operation signal which the operation reception part 20 outputs in accordance with the operation of the user. Further, the control unit 11 outputs a control signal for controlling the first switch SW1 to the first driving circuit 17 , and outputs a control signal for controlling the second switch SW2 to the second driving circuit 18 . Further, the control unit 11 can adjust the power supply (that is, the amount of power) supplied from the AC power source 2 to the load 3 per unit time by phase control or PWM (Pulse Width Modulation) control, so as to The first switch SW1 is controlled in this way (hereinafter, referred to as "load control"). In the present embodiment, the control unit 11 performs phase control (so-called reverse phase control), that is, controls the first switch SW1 to be in an on state from the start point of the half cycle of the AC voltage Vac to the on-period, and the on-period elapses After that, the first switch SW1 is controlled to be turned off. The first switch SW1 is switched from the OFF state to the ON state at the start point of the half cycle of the AC voltage Vac, so that noise generated when switching to the ON state can be reduced. In addition, the first switch SW1 is switched from the OFF state to the ON state at the start point of the half cycle of the AC voltage Vac, but is not limited to being switched from the OFF state to the ON state at the zero-cross point of the AC voltage Vac. It switches from the OFF state to the ON state at the time when the zero-cross is detected.

In addition, the control unit 11 controls the second switch SW2 to be in the ON state at the switching timing of the ON/OFF switching of the first switch SW1 in the middle of each half cycle of the AC voltage Vac. In the case of reverse phase control, the control unit 11 controls the second switch SW2 to be on at the switching timing when the first switch SW1 is switched from on to off in the middle of each half cycle of the AC voltage Vac. When the second switch SW2 is turned on, a current path RT1 or RT2 is formed through which the current flows from the AC power source 2 to the capacitive element 12 . At the switching time point, the capacitor element 12 is connected in parallel with the first switch SW1 between the pair of connection terminals TA1 and TA2, so that the reverse voltage generated when the first switch SW1 is turned off can be converted from the capacitor The element 12 absorbs and reduces the noise superimposed on the AC voltage Vac.

(2.3) Operation of the load control device Next, the operation of the load control device 1 of the present embodiment will be described with reference to FIGS. 1 and 2 .

(2.3.1) Start Action First, the start-up operation at the start of energization of the load control device 1 of the present embodiment will be described.

Immediately after the start of the load control device 1, that is, shortly after the power supply is started, the first switch SW1 and the second switch SW2 are turned off, and the DC voltage obtained by full-wave rectification of the AC voltage Vac by the rectifier circuit DB1 is supplied to the power supply. Section 19. The power supply unit 19 converts the DC voltage input from the rectifier circuit DB1 into a DC voltage having a predetermined voltage value and supplies it to the control unit 11, and the control unit 11 starts to operate.

The control unit 11 controls the ON/OFF of the first switch SW1 in accordance with the operation signal input from the operation reception unit 20 . When a signal to turn off the load 3 is input from the operation accepting unit 20 , the control unit 11 controls the first drive circuit 17 to control the first switch SW1 (ie, the MOSFETs Q11 and Q12 ) to be in an off state, thereby cutting off the load from the AC power source 2 . 3 power supply. When the control unit 11 controls the first switch SW1 to be in an off state, it controls the second drive circuit 18 to control the second switch SW2 (that is, the MOSFETs Q21 and Q22 ) to be in an off state.

(2.3.2) Dimming action Next, the dimming operation of the load control device 1 of the present embodiment will be described with reference to FIG. 2 . 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 sections 15 and 16, the control signals Sa1 and Sa2 input to the gate terminals of the MOSFETs Q11 and Q12, and the input Control signals Sb1 and Sb2 to the gate terminals of MOSFETs Q21 and Q22. The detection signal ZC1 is a detection signal obtained by the zero-cross detection unit 15 , and the detection signal ZC2 is a detection signal obtained by the zero-cross detection unit 16 . Moreover, the detection signals ZC1 and ZC2 are changed from the "H" level to the "L" level, and it is regarded that the detection signals ZC1 and ZC2 have been generated. That is, the detection signals ZC1 and ZC2 are signals that change from the "H" level to the "L" level when the zero-cross point is detected.

First, the operation of the load control device 1 in the half cycle of the positive polarity of the AC voltage Vac will be described. The load control device 1 detects the zero-crossing point of the AC voltage Vac serving as the reference of the phase control by the zero-crossing detecting unit 15 . When the AC voltage Vac moves from the negative half cycle to the positive half cycle, and the AC voltage Vac reaches the positive polarity predetermined value "Vzc", the zero-cross detection unit 15 outputs a detection signal ZC1. In this embodiment, the generation time of the detection signal ZC1 is the first time t1, and the period from the start point (zero-cross point) t0 of the half cycle to the first time t1 is the first period T1.

However, in the first period T1 from the start point t0 of the half cycle to the first time point t1 , the control unit 11 outputs to the first drive circuit 17 a control signal for setting the first switch SW1 in an off state. The first driving circuit 17 outputs an "off" signal as the control signals Sa1 and Sa2 in accordance with the control signal. Thereby, in the first period T1, both of the two MOSFETs Q11 and Q12 are turned off, and the first switch SW1 is turned off. Moreover, at the first time point t1, the control unit 11 outputs a control signal to the first drive circuit 17, and outputs an "ON" signal from the first drive circuit 17 as the control signals Sa1 and Sa2. Thereby, at the first time point t1, the first switch SW1 is switched from the OFF state to the ON state, and electric power is supplied from the AC power supply 2 to the load 3.

The control unit 11 outputs a control signal for setting the MOSFET Q11 in the OFF state to the first drive circuit 17 at the third time t3 after the ON period (second period) T2 has passed from the first time t1 . The first drive circuit 17 outputs an "off" signal as the control signal Sa1 when outputting the "on" signal as the control signal Sa2 in accordance with the control signal. The control unit 11 determines the length of the ON period T2 in accordance with the dimming level (that is, the power supplied to the load 3 ) input from the operation accepting unit 20 . Thereby, in the conduction period T2 from the first time point t1 to the third time point t3 , the first switch SW1 is maintained in the ON state, and power is supplied from the AC power supply 2 to the load 3 . Then, at the third time t3, the first switch SW1 is switched from the ON state to the OFF state, and the electric power supplied from the AC power supply 2 to the load 3 is blocked.

However, at the second time point t2 before the third time point t3, the control unit 11 outputs to the second drive circuit 18 a control signal for setting the second switch SW2 in the ON state. The second driving circuit 18 outputs the "on" signal as the control signals Sb1 and Sb2 in accordance with the control signal. Thereby, both of the two MOSFETs Q21 and Q22 are turned on, and the second switch SW2 is turned on. That is, the control unit 11 controls the second switch SW2 to the on state at the switching time point (the third time point t3 ) when the first switch SW1 is switched from the ON state to the OFF state, and the second switch SW2 When the state is turned on, the first switch SW1 is switched from the on state to the off state. Therefore, at the switching time point (the third time point t3 ), the reverse voltage generated by the inductance of the system can be absorbed by the capacitive element 12 . In addition, by absorbing the reverse voltage in the capacitive element 12, high-speed switching of the first switch SW1 becomes possible, and switching loss in the first switch SW1 can be reduced.

When the control unit 11 turns off the MOSFETQ11 of the first switch SW1 at the third time t3, at the fourth time t4 after a predetermined surge absorption period has elapsed from the third time t3, only the MOSFETQ22 is turned on. The ON control signal is output to the second driving circuit 18 . When the second driving circuit 18 outputs the "on" signal as the control signal Sb2 in accordance with the control signal, the "off" signal is output as the control signal Sb1. Thereby, from the third time point t3 to the end of the half cycle of the positive polarity of the AC voltage Vac, the MOSFET Q21 is controlled to be in an off state, and the second switch SW2 is turned off. That is, the control unit 11 switches the second switch SW2 from the ON state to the OFF state when a predetermined time (surge absorption period) elapses from the switching time point (third time point t3 ). The surge absorption period is preferably set to a period longer than the period assumed to be generated by the inductance or the like of the system at the switching time point (the third time point t3 ). Therefore, after the surge absorption period has elapsed, by blocking the current path RT1 through which the current flows from the AC power source 2 to the capacitive element 12, the current flowing to the load 3 via the capacitive element 12 when the first switch SW1 is turned off can be suppressed. , and the dimming characteristics of the load 3 can be improved. Furthermore, at the fourth time point t4, the MOSFETQ22 is maintained in the ON state and the MOSFETQ21 is controlled to be in the OFF state, the charge accumulated in the capacitor element 12 is discharged to the AC power supply 2 via the body diode D21 and the MOSFETQ22 of the MOSFETQ21.

After that, the control unit 11 outputs a control signal to the second drive circuit 18 to turn off the MOSFET Q22 at the fifth time point t5 after the predetermined discharge period T10 has passed from the third time point t3. The second driving circuit 18 outputs the “off” signal as the control signals Sb1 and Sb2 in accordance with the control signal, and sets the MOSFETs Q21 and Q22 to the off state, thereby blocking the discharge path from the capacitive element 12 . Among them, the discharge period T10 is preferably set to a period longer than the time required to discharge the electric charge accumulated in the capacitive element 12 .

Furthermore, the control unit 11 turns off the MOSFET Q12 at the sixth time point t6 just before a predetermined time (for example, 300 [μs]) from the end point (zero-cross point) t7 of the half cycle of the positive polarity of the AC voltage Vac The control signal is output to the first driving circuit 17 . The first driving circuit 17 outputs an "OFF" signal as the control signals Sa1 and Sa2 in accordance with the control signal. Among them, the period from the third time point t3 to the sixth time point t6 is called the third period T3, and the period from the sixth time point t6 to the end point (zero-cross point) t7 of the positive polarity half cycle is called the period is the fourth period T4. In the fourth period T4, both of the two MOSFETs Q11 and Q12 are turned off, and the first switch SW1 is turned off.

In addition, the operation of the load control device 1 when the AC voltage Vac is in the half cycle of the negative polarity is basically the same as that of the half cycle of the positive polarity.

In the negative half cycle, when the AC voltage Vac reaches the predetermined value "-Vzc" of the negative polarity, the zero-cross detection unit 16 outputs a detection signal ZC2. In the present embodiment, the period from the start point t0 ( t7 ) of the negative half cycle to the first time point t1 when the detection signal ZC2 is generated is referred to as the first period T1 . In addition, the third time point t3 is the time point that elapses from the first time point t1 to the ON period that matches the length of the dimming level, and the sixth time point t6 is only a predetermined time away from the end point t7 (t0) of the negative polarity half cycle. (eg 300[μs]). Even in the half cycle of negative polarity, the second switch SW2 is turned on at the second time t2 before the switching time (third time t3) when the first switch SW1 is switched from the on state to the off state. A current path RT2 is formed through which current flows from the AC power source 2 to the capacitive element 12 . Therefore, at the switching time point (the third time point t3 ), the reverse voltage generated by the inductance or the like of the system can be absorbed by the capacitive element 12 . In addition, the second switch SW2 is in the period from the start point of the half cycle of the negative polarity of the AC voltage Vac to the second time t2 and the period from the fourth time t4 to the end point t7 of the half cycle of the negative polarity , it is turned off, and the current path from the AC power source 2 to the capacitive element 12 is blocked. Therefore, when the first switch SW1 is turned off, the current flowing to the load 3 via the capacitive element 12 can be suppressed, and the load 3 can be suppressed from being turned on, compared to the case where the second switch SW2 is kept on during the negative half cycle. Deterioration of dimming performance.

The load control device 1 of the present embodiment dims the load 3 by alternately switching the operation of the positive half cycle and the half cycle of the negative polarity described above, ie, every half cycle of the AC voltage Vac. Furthermore, if the predetermined value of positive polarity "Vzc" and the predetermined value of negative polarity "-Vzc" are fixed values, from the start point t0 of the half cycle to the first time point (the time point when the detection signal ZC1 or ZC2 is generated) ) The time until t1 is a substantially constant length of time.

Therefore, the time from the starting point t0 of the half cycle to the switching time point (the third time point t3 ), that is to say, the total time of the first period T1 and the second period T2, that is, the “on period” is matched with dimming The level causes the length to vary. In other words, the ON period is a variable length of time, and the phase relative to the switching time point (the third time point t3 ) of the AC voltage Vac changes according to the dimming level. That is, when the light output of the load 3 is decreased, a shorter conduction period is set, and when the light output of the load 3 is increased, a longer conduction period is set. Therefore, the load control device 1 can change the magnitude of the light output of the load 3 according to the dimming level received by the operation accepting part 20 .

(3) Modifications Embodiment 1 is only one of various embodiments of the present invention. Embodiment 1 can be variously changed in accordance with the design or the like as long as the object of the present invention is achieved. For example, the specific circuit shown in FIG. 1 is only an example of the load control device 1 of the present invention, and various changes can be made according to the design and the like. Each drawing described in the present invention is a schematic drawing, and each ratio of the size and thickness of each constituent element in each drawing does not necessarily reflect the actual size ratio. In addition, the same functions as those of the control unit 11 of the load control device 1 of the first embodiment can be realized by a control method, a (computer) program, or a temporary recording medium in which the program is recorded.

Hereinafter, a modification of Embodiment 1 will be described. The modified examples described below can be appropriately combined and used.

(3.1) Modification 1 FIG. 3 shows a schematic circuit diagram of the load control device 1 according to Modification 1 of the first embodiment. The load control device 1 of the modified example 1 connects the connection point P2 of the MOSFETs Q21 and Q22 to the reference potential of the power supply unit 19, and the capacitive element 12 is different from the above-described embodiment in that the first capacitive element 121 and the second capacitive element 122 are included. 1. The first capacitive element 121 is connected between the connection terminal TA1 and the MOSFETQ21, and the second capacitive element 122 is connected between the connection terminal TA2 and the MOSFETQ22. In Modification 1, the connection point P1 of the MOSFETs Q11 and Q12 and the connection point P2 of the MOSFETs Q21 and Q22 are electrically connected. Hereinafter, about the same structure as Embodiment 1, the common code|symbol is attached|subjected and description is abbreviate|omitted suitably.

The control unit 11 performs reverse phase control on the first switch SW1, and controls the second switch SW2 to be on at the switching timing of the switching of the first switch SW1 from the on state to the off state in each half cycle of the AC voltage Vac. condition. Thereby, the reverse voltage generated by the inductance of the system and the like can be absorbed by the first capacitive element 121 and the second capacitive element 122 at the switching timing. When a predetermined time elapses from the switching time point, the control unit 11 controls both of the MOSFETs Q21 and Q22 to be in an off state, and the electric charges accumulated in the first capacitive element 121 or the second capacitive element 122 pass through the body diodes D21 of the MOSFETs Q21 and Q22 , D22 , are discharged via the reference potential of the power supply unit 19 .

Furthermore, in Modification 1, the first capacitive element 121 and the second capacitive element 122 are constituted by capacitors, but they may be an electric double layer capacitor, a secondary battery, or the like. In addition, each of the first capacitive element 121 and the second capacitive element 122 is not limited to being composed of a single capacitor, and may be composed of a plurality of capacitors connected in series or in parallel.

(3.2) Other modifications The load control device 1 of the present invention includes a computer system in the control unit 11 and the like. A computer system mainly includes a processor and a memory as hardware. The function of the load control device 1 of the present invention is realized by executing the program recorded in the memory of the computer system by the processor. The program can be pre-recorded in the memory of the computer system, or provided through an electrical communication line, or recorded on a temporary recording medium such as a memory card, CD-ROM, hard disk drive, etc., which can be read by the computer system. The processor of a computer system consists of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large integrated circuit (LSI). So-called integrated circuits such as IC or LSI are called differently depending on the degree of integration, including system LSI, VLSI (Very Large Scale Integration/very large integrated circuit), or ULSI (Ultra Large Scale Integration/ very large integrated circuits). Furthermore, FPGAs (Field-Programmable Gate Array/Field Programmable Gate Array), which are programmed after the manufacture of the LSI, or the reconfiguration of the coupling relationship in the LSI, or the reconfiguration of the circuit partitions in the LSI, are possible logics. The device can also be employed as a processor. A plurality of electronic circuits may be integrated into one wafer, or may be distributed over a plurality of wafers. A plurality of wafers may be collected in one device, or may be distributed in a plurality of devices. The so-called computer system includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller can also be composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

In addition, it is not a necessary configuration of the load control device 1 that at least a part of the functions of the load control device 1 are integrated into one housing, and the components of the load control device 1 may be distributed and provided in a plurality of housings. For example, the touch panel included in the operation accepting unit 20 may be provided in a casing different from that of the control unit 11 . In addition, at least a part of the functions of the control unit 11 and the like can be realized by, for example, a server, a cloud (cloud computing), or the like.

In the first embodiment, the control unit 11 controls the second switch SW2 from the OFF state to the ON state before the switching time point (third time point t3 ). The OFF state is controlled to the ON state. That is, the control unit 11 may control the second switch SW2 from the off state to the on state at the same timing as when the first switch SW1 is controlled from the off state to the on state, or may control the first switch SW2 from the off state to the on state. The reverse voltage generated when the switch SW1 is turned off is suppressed by the capacitive element 12 .

In Embodiment 1, the control unit 11 performs reverse phase control on the first switch SW1, but may perform positive phase control on the first switch SW1. That is, the control unit 11 may control the first switch SW1 to be in the OFF state from the start point of the half cycle of the AC voltage Vac until the interruption period elapses, and then control the first switch SW1 to be in the OFF state after the interruption period has elapsed. On state. In the positive phase control, the control unit 11 controls the second switch SW2 to be in an on state at the switching timing of the first switch SW1, so that the reverse voltage generated at the switching timing can be reduced. During the positive phase control, the control unit 11 may control the second switch SW2 to be on at the switching timing when the first switch SW1 is switched from off to on in the middle of each half cycle of the AC voltage Vac.

Moreover, in Embodiment 1, although the AC power supply 2 is a single-phase 100 [V], 60 [Hz] commercial power supply, it may be a single-phase 100 [V], 50 [Hz] commercial power supply. In addition, the voltage value of the AC power supply 2 is not limited to 100 [V].

In addition, in Embodiment 1, although the load control apparatus 1 is a one-shot switch, other structures may be sufficient. For example, the load control device 1 may be a so-called three-way switch capable of connecting three wires. In addition, the load control device 1 may be a so-called four-way switch capable of connecting four wires. When the load control device 1 constitutes a three-way switch, by combining two load control devices 1, the energization state of the load 3 can be switched, for example, at two places of the upper part and the lower part of the stairs of a building. Furthermore, in the first embodiment, the load control device 1 is a 2-wire switch in which two wires of the L-phase and the N-phase are connected, but the load control device 1 may be three of the N-phase shared by the L-phase, the load, the power supply, and the load. 3-wire switch to which wires are connected.

In Embodiment 1, the zero-cross detection unit 15 is configured to detect zero-cross when the voltage between the switches is switched from negative to positive when the voltage between the connection terminal TA1 and the ground becomes equal to or greater than the reference value, and the reverse operation is also possible. That is, the zero-cross detection unit 15 may be configured to detect a zero-cross when the voltage between the switches is switched from positive to negative when the voltage between the connection terminal TA1 and the ground does not reach the reference value. Similarly, the zero-cross detection unit 16 is configured to detect the zero-cross when the voltage between the switches is switched from positive to negative when the voltage between the terminal TA2 and the ground becomes equal to or higher than the reference value, and can also operate in the reverse direction. That is, the zero-cross detection unit 16 is configured to detect a zero-cross when the voltage between the terminals TA2 and the ground does not reach the reference value and the voltage between the switches is switched from negative to positive.

In addition, the load 3 is not limited to the illuminating device containing the light source which consists of LEDs, and may be the illuminating device containing the light source other than LED. Further, the load 3 is not limited to the lighting device, and may be, for example, a ventilation fan, a display device, an electric circuit breaker, an air conditioner or an anti-theft device (including devices, systems, and equipment). In addition, the load 3 is not limited to one device, and may be a plurality of devices electrically connected in series or in parallel.

In addition, the load control device 1 may further include an operation terminal for connecting a sub-unit. The slave unit includes, for example, a contact portion such as a snap switch, and the load control device 1 detects whether the contact portion is on/off. At this time, the load control device 1 controls the first switch SW1 to switch the operation state of the first switch SW1 in accordance with the operation of the slave unit (on/off of the contact portion). That is, in the slave unit, for example, whenever the press switch is pressed to turn on the contact portion, the load control device 1 operates so as to switch between the ON state and the OFF state of the first switch SW1. In short, in the load control device 1, the control of the first switch SW1 can be performed not only in accordance with the output of the operation accepting unit 20, but also in accordance with the operation of the sub-machine. Therefore, the load control device 1 and the sub-machine can be switched between the two places where the load 3 is energized by, for example, being provided separately in two places at the upper end part and the lower end part of the stairs of the building.

In addition, the load control device 1 may be provided with a sensor circuit, a timer circuit, or the like in addition to or in place of the operation accepting unit 20 . As an example, the sensor circuit includes a human sensor and/or a brightness sensor that detects whether there is a human body. The load control device 1 can control the first switch SW1 based on the outputs of these sensor circuits, timer circuits, and the like.

Furthermore, in the above-described embodiment, the first switch SW1 has two MOSFETs Q11 and Q12, but it is not limited to MOSFETs, and other semiconductor switches may be used. For example, the first switch SW1 may be realized by a 3-terminal bidirectional thyristor (bidirectional switch), or may be realized by a semiconductor element having a dual gate (separated gate) structure using a semiconductor material with a wide band gap such as GaN (gallium nitride). accomplish.

(implementation type 2) The load control device 1A of this embodiment differs from the load control device 1 of the first embodiment in that a series circuit of the second switch SW21 and the capacitive element 12 is connected between the output terminals of the rectifier circuit DB1 as shown in FIG. 4 . That is, the load control device 1A of the second embodiment includes a rectifier circuit DB1 that rectifies the AC voltage Vac input via the pair of connection terminals TA1 and TA2. Then, a series circuit of the second switch SW21 and the capacitive element 12 is connected between the output terminals of the rectifier circuit DB1. Hereinafter, about the same structure as Embodiment 1, the common code|symbol is attached|subjected and description is abbreviate|omitted suitably.

In the load control device 1A of the second embodiment, the second switch SW21 is electrically connected to the connection terminal TA1 via the diode D1, and is electrically connected to the connection terminal TA2 via the diode D2. That is, the second switch SW21 is inserted into the current path RT3 through which the current flows from the AC power source 2 to the capacitive element 12 via the connection terminal TA1 or TA2. When the second switch SW21 is turned on, the current flows from the AC power source 2 to the capacitor element 12, and when the second switch SW21 is turned off, the current from the AC power source 2 to the capacitor element 12 is blocked. .

Furthermore, the load control device 1A of the second embodiment further includes a series circuit of a resistor R1 (impedance element) connected in parallel with the capacitive element 12 and a third switch SW3 . Then, the control unit 11 controls the third switch SW3 to the on state while the second switch SW21 is controlled to the off state. In addition, the control part 11 controls the 3rd switch SW3 to an OFF state while controlling the 2nd switch SW21 to an ON state.

In the present embodiment, the third switch SW3 is, for example, a MOSFET, but may be realized by a semiconductor switch such as a transformer or a thyristor, or may be realized by a contact of a mechanical repeater or the like. In addition, in the present embodiment, the impedance element is realized by the resistor R1, but the impedance element is not limited to the control unit 11 and can be appropriately changed. In addition, the electric charge accumulated in the capacitive element 12 can be supplied to a power supply circuit such as a series regulator, and can also be used for electric power supplied to a circuit such as the control unit 11 .

In the load control device 1A according to the second embodiment, for example, the first switch SW1 is controlled in reverse phase, and the second switch SW21 is controlled to be on at the switching timing when the first switch SW1 is switched from the on state to the off state. condition. Accordingly, at the switching time point, the reverse voltage generated by the inductance of the system can be absorbed by the capacitive element 12 , and the noise generated in the load control device 1A can be reduced. The control unit 11 switches the second switch SW21 from the ON state to the OFF state when a predetermined time elapses from the switching time point. Then, the control unit 11 controls the third switch SW3 to be turned on when the second switch SW21 is turned off, so that the electric charge accumulated in the capacitive element 12 can be discharged through the resistor R1.

(Summarize) As described above, the load control device ( 1 , 1A) of the first aspect includes: a pair of connection terminals ( TA1 , TA2 ); a first switch ( SW1 ); a capacitive element ( 12 ); and a second switch ( SW2 , SW21 ) ); and the control section (11). A series circuit of an AC power source (2) and a load (3) is connected to a pair of connection terminals (TA1, TA2). The first switch (SW1) is connected between a pair of connection terminals (TA1, TA2), and switches between the disconnected state that blocks the power supplied from the AC power source (2) to the load (3), and the switch from the AC power source (2) to the disconnected state. Either of the ON states in which power is supplied to the load (3). The second switches (SW2, SW21) are inserted into the current paths (RT1 to RT3). The current paths ( RT1 to RT3 ) are paths through which current flows from the AC power source ( 2 ) to the capacitive element ( 12 ) via at least one of the pair of connection terminals ( TA1 , TA2 ). The control unit (11) controls the first switch (SW1) to be in the ON state during each half cycle of the AC voltage (Vac) of the AC power supply (2) during the conduction period determined according to the power supplied to the load (3), The first switch ( SW1 ) is controlled to be turned off during the off period other than the on period. The control unit (11) controls the second switch (SW2, SW21) to be in the ON state at the switching timing of the ON/OFF switching of the first switch (SW1) in the middle of each half cycle of the AC voltage (Vac). .

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

In the load control device ( 1 , 1A) of the second aspect, in the first aspect, the series circuit of the second switch ( SW2 ) and the capacitive element ( 12 ) is connected in parallel with the first switch ( SW1 ). According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

The load control device ( 1A) of the third aspect further includes a rectifier circuit ( DB1 ) that rectifies the AC voltage (Vac) input via the pair of connection terminals ( TA1 , TA2 ), as in the first aspect. A series circuit of a second switch ( SW21 ) and a capacitive element ( 12 ) is connected between the output terminals of the rectifier circuit ( DB1 ).

According to this aspect, a low-loss load control device (1A) capable of reducing noise can be provided.

The load control device ( 1A) of the fourth aspect further includes a series circuit of an impedance element ( R1 ) and a third switch ( SW3 ) connected in parallel with the capacitive element ( 12 ) as in the third aspect. The control unit ( 11 ) controls the third switch ( SW3 ) to be in the ON state while the second switch ( SW21 ) is controlled to be in the OFF state.

According to this aspect, a low-loss load control device (1A) capable of reducing noise can be provided.

In the load control device ( 1 , 1A) of the fifth aspect, like any one of the first to fourth aspects, the control unit ( 11 ) switches the first switch from the start point of the half cycle of the AC voltage (Vac) to the conduction period. ( SW1 ) is controlled to be in the ON state, and the first switch ( SW1 ) is controlled to be in the OFF state after the ON period has elapsed.

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

In the load control device ( 1 , 1A) of the sixth aspect, as in the fifth aspect, the control unit ( 11 ) switches the second switch ( SW1 ) at the switching timing of switching the first switch ( SW1 ) from the ON state to the OFF state. (SW2, SW21) are controlled to be on.

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

In the load control device ( 1 , 1A) of the seventh aspect, as in the fifth aspect, the control unit ( 11 ) switches the second switch ( SW1 ) to the off state at the switching timing of switching the first switch ( SW1 ) from the ON state to the OFF state. (SW2, SW21) are controlled from the OFF state to the ON state.

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

In the load control device ( 1 , 1A) of the eighth aspect, like any one of the fifth to seventh aspects, the control unit ( 11 ) switches the first switch ( SW1 ) from the ON state to the OFF state during the switching time When the predetermined time elapses, the second switch (SW2, SW21) is switched from the ON state to the OFF state.

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

In the load control device ( 1 , 1A) of the ninth aspect, as in any one of the first to fourth aspects, the control unit ( 11 ) controls the first half cycle of the AC voltage (Vac) until the interruption period elapses from the start point of the half cycle. The switch ( SW1 ) is controlled to be turned off, and the first switch ( SW1 ) is controlled to be turned on after the shut-off period has elapsed.

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

The load control device (1, 1A) of the tenth aspect is like any one of the first to ninth aspects, and the load (3) includes a dimmable lighting load.

According to this aspect, a low-loss load control device (1, 1A) that can reduce noise can be provided.

Not limited to the above, various configurations (including modifications) of the load control device (1, 1A) according to Embodiment 1 or 2 can be implemented by the control method of the load control device (1, 1A), the (computer) program, or the temporary recording of the program. Sexual recording media, etc.

The configurations of the second to tenth aspects are not essential configurations of the load control device (1, 1A), and can be appropriately omitted.

1: Load control device 2: AC power 3: load 11: Control Department 12: Capacitive components 15: ZC detection department 16: ZC detection department 17: The first drive circuit 18: The second drive circuit 19: Power Department 20:Operation Acceptance Department D1, D2: Diodes D11, D12, D21, D22: Body diodes DB1: rectifier circuit Q11, Q12, Q21, Q22: MOSFET R1: Impedance element RT1~RT3: Current path Sa1, Sa2, Sb1, Sb2: control signal SW1: 1st switch SW2, SW21: 2nd switch SW3: 3rd switch TA1, TA2: connection terminal Vac: AC voltage V1: load voltage ZC1: detection signal ZC2: detection signal

[FIG. 1] FIG. 1 is a schematic circuit diagram of a load control device according to Embodiment 1. [FIG. [ Fig. 2] Fig. 2 is a time-point diagram showing the operation of the load control device as described above. 3] FIG. 3 is a circuit diagram showing a schematic configuration of a load control device according to Modification 1 of Embodiment 1. [FIG. [Fig. 4] Fig. 4 is a schematic circuit diagram of a load control device according to Embodiment 2. [Fig.

1: Load control device

2: AC power

3: load

11: Control Department

12: Capacitive components

15: ZC detection department

16: ZC detection department

17: The first drive circuit

18: The second drive circuit

19: Power Department

20:Operation Acceptance Department

D1: Diode

D2: Diode

D11: Body Diode

D12: Body Diode

D21: Body Diode

D22: Body Diode

DB1: rectifier circuit

Q11:MOSFET

Q12:MOSFET

Q21:MOSFET

Q22:MOSFET

RT1: Current Path

RT2: Current Path

Sa1: control signal

Sa2: control signal

Sb1: Control signal

Sb2: Control signal

SW1: 1st switch

SW2: 2nd switch

TA1: Connection terminal

TA2: Connection terminal

Vac: AC voltage

V1: load voltage

ZC1: detection signal

ZC2: detection signal

Claims (10)

A load control device comprising: A pair of connecting terminals are connected to the series circuit of the AC power supply and the load; The first switch is connected between the pair of connection terminals, and can be switched between an OFF state that blocks the supply of power from the AC power source to the load, and a switch that enables power supply from the AC power source to the load. any one of the pass states; Capacitive element; a second switch inserted into a current path through which current flows from the AC power source to the capacitive element via at least one of the pair of connection terminals; and control department; The control unit controls the first switch to be in an ON state during each half cycle of the AC voltage of the AC power supply during an ON period determined according to the power supplied to the load, and during an OFF period other than the ON period, The first switch is controlled to be in an off state, The control unit controls the second switch to be in the ON state at the switching timing of the ON/OFF switching of the first switch in the middle of each half cycle of the AC voltage. The load control device of claim 1, wherein, The series circuit of the second switch and the capacitive element is connected in parallel to the first switch. The load control device of claim 1, further comprising: a rectifier circuit for rectifying the AC voltage input via the pair of connection terminals, A series circuit of the second switch and the capacitive element is connected between the output terminals of the rectifier circuit. The load control device of claim 3, further comprising: A series circuit composed of an impedance element and a third switch connected in parallel with the capacitive element, The control unit controls the third switch to the on state while the second switch is controlled to the off state. The load control device of any one of claims 1 to 4, wherein, The control unit controls the first switch to be in an ON state from the start point of the half cycle of the AC voltage until the conduction period elapses, and controls the first switch to an OFF state after the conduction period has elapsed. The load processing apparatus of claim 5, wherein, The control unit controls the second switch to be in the ON state at the switching time point when the first switch is switched from the ON state to the OFF state. The load processing apparatus of claim 5, wherein, The control unit controls the second switch from the off state to the on state at the switching timing when the first switch is switched from the on state to the off state. The load processing apparatus of claim 5, wherein, The control unit switches the second switch from the on state to the off state when a predetermined time elapses from the switching time point when the first switch is switched from the on state to the off state. The load control device of any one of claims 1 to 4, wherein, The control unit controls the first switch to the OFF state until the interruption period passes from the start point of the half cycle of the AC voltage, and controls the first switch to the ON state after the interruption period. The load control device of any one of claims 1 to 4, wherein, This load contains a dimmable lighting load.

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