JP2012248093A - Two-wire type load control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-wire type load control device capable of preventing a load from malfunctioning due to noise even when a light load such as an LED bulb is connected.SOLUTION: The two-wire type load control device includes an auxiliary opening/closing part 17 which is first conducted when energizing a load 3, a main opening/closing part 11 which supplies power more stably at a side closer to the load 3 than the auxiliary opening/closing part 17 after the conduction, the two opening/closing parts connected in series between a commercial power source 2 and the load 3, power supply parts 14, 15, 16 for securing its own operation power, and a noise filter 19 of a DC system provided at a side closer to the commercial power source 2 and the load 3 than the main opening/closing part 11 for removing noise superposed on the commercial power source 2. The noise filter 19 has a diode bridge 191, a capacitor 192 and a Zener diode 193.

Description

  The present invention relates to a two-wire load control device, and more particularly to a load switching circuit thereof.

  Conventionally, in order to control the on / off of loads such as lighting devices and ventilation fans, load control devices using non-contact switch elements such as triacs instead of 2-wire switches whose contacts are mechanically opened and closed (electronic Switch) has been put into practical use (see Patent Document 1). Such a load control device generally has a two-wire connection from the viewpoint of wiring saving, and is connected in series between a commercial power supply (AC power supply) and a load.

  FIG. 4 shows a circuit configuration of a conventional two-wire load control device 50 connected in series between a commercial power source 2 and a load 3 described in Patent Document 1. The load control device 50 includes a main opening / closing unit 51 and an auxiliary opening / closing unit 57 that control on / off of the load 3, a control unit 53 that controls conduction of the main opening / closing unit 51 and the auxiliary opening / closing unit 57, and a control unit 53. It consists of a power supply circuit for supplying drive power.

  The load control device 50 includes two load switching circuits in order to control on and off of a load 3 such as a lighting device. The auxiliary opening / closing part 57 is configured by using a thyristor 57a as a switch element, and when the load 3 is energized, the auxiliary opening / closing part 57 is first conducted to provide an energization path. The main opening / closing part 51 is configured by using a triac 51a as a main switching element, and provides a more stable energization path on the side closer to the load 3 than the auxiliary opening / closing part 57 after the auxiliary opening / closing part 57 is conducted.

  When the operation handle (SW) 4 for activating the load 3 is operated, the control unit 53 outputs a control signal, whereby the switch element 56c of the third power supply unit 56 is turned on, and the switch element 56b is turned on. To do. As a result, the current output from the rectifying unit 52 flows through the switch element 56b and charges the buffer capacitor 58. When the buffer capacitor 58 is charged, current flows through the Zener diode 56a to the gate of the thyristor 57a of the auxiliary opening / closing part 57, whereby the thyristor 57a becomes conductive. Since the thyristor 57a is connected between the output terminals of the rectifier unit 52, the current rectified by the rectifier unit 52 flows to the load 3 due to the conduction of the thyristor 57a. Since this current also flows through the gate of the triac 51a of the main switching unit 51, when the voltage becomes higher than the trigger voltage of the triac 51a, the triac 51a, that is, the main switching unit 51 becomes conductive. Once the main opening / closing part 51 becomes conductive (closed state), the current continues to flow. However, when the commercial current reaches the zero cross point, the triac 51a self-extinguishes and the main opening / closing part 51 becomes non-conductive (open state). Become. When the main opening / closing part 51 becomes non-conductive (open state), a current flows from the rectifying part 52 through the third power supply part 56 to the first power supply part 54, and an operation for securing the self-circuit power supply of the load control device 50 is performed. In other words, the self-circuit power supply securing of the load control device 50, the conduction of the auxiliary opening / closing part 57, and the conduction operation of the main opening / closing part 51 are repeated every half cycle of the alternating current.

JP 2008-97535 A

  By the way, various noise sources exist in an environment where the load control device is used. It is known that when burst noise is superimposed on the commercial power supply, the thyristor or triac becomes conductive due to the rise in the critical off voltage even though the trigger signal is not input. In order to prevent such a malfunction, noise filters 51b and 57b each composed of a resistor and a capacitor are connected to the triac 51a and the thyristor 57a.

  On the other hand, loads with low power consumption, such as LED bulbs, are increasing as control targets of this load control device in recent years. The triac 51a and its noise filter 51b are provided closer to the commercial power source 2 and the load 3 than the rectifying unit 52, that is, on the AC system. Since the capacitor constituting the noise filter 51b passes an alternating current, a leakage current corresponding to the capacitance of the capacitor flows to the load, and if the power consumption of the load is small, the load may malfunction such as erroneous lighting of the LED. There is a risk that.

  The present invention has been made to solve the above-described problems of the conventional example, and even when a light load such as an LED bulb is connected, malfunction of a switch element such as a thyristor or a triac due to burst noise is prevented. An object of the present invention is to provide a two-wire load control device capable of preventing malfunctions of these light loads accompanying an increase in leakage current due to the addition of a noise filter.

  The two-wire load control device according to one aspect of the present invention is connected in series between a commercial power source and a load, and when the load is energized, the auxiliary opening / closing portion that is turned on first and the auxiliary opening / closing portion are turned on A main switching unit that supplies more stable power on the side closer to the load than the auxiliary switching unit, and a power supply unit for securing its own operating power, and the commercial power source and the main switching unit A noise filter of a direct current system for removing noise superimposed on the commercial power supply is provided on the side close to the load.

In addition, a two-wire load control device according to another aspect of the present invention includes a main switching unit in which a main electrode of a main switch element is connected in series to a commercial power source and a load, and controls supply of power to the load. A rectifying unit connected between the main electrodes of the main switch element, a control unit for controlling on / off of a load according to an external signal, and for stably supplying power to the control unit A first power supply unit, a second power supply unit that is supplied with power from both ends of the main opening / closing unit via a rectification unit, and supplies power to the first power supply unit when the load is turned off; Power is supplied from both ends of the main switching unit via the rectification unit, and when the load is turned on, a third power supply unit that supplies power to the first power supply unit and an output terminal of the rectification unit When connected and supplied with power to the load, it conducts before the main switching part That an auxiliary opening portion,
The auxiliary switching unit uses a thyristor as a switching element, the main switching unit uses a triac as the main switching element, is provided closer to the commercial power supply and the load than the main switching unit, and is superimposed on the commercial power supply Further, a noise filter of a DC system for removing the noise is further provided.

  The noise filter preferably includes a diode bridge and a capacitor connected to the diode bridge.

  The noise filter preferably includes a Zener diode connected in parallel to the capacitor.

  According to the configuration of the present invention, the noise filter for removing the noise superimposed on the commercial power source is a DC system and is provided closer to the commercial power source and the load than the main switching unit. Even if burst noise is superimposed on the main opening / closing section and the auxiliary opening / closing section, there is no possibility of erroneous conduction. Further, since the noise filter is a DC system, the leakage current flowing through the load is extremely small.

1 is a circuit diagram showing a configuration of a two-wire load control device according to an embodiment of the present invention. The circuit diagram which shows the structure of the conventional 2-wire type load control apparatus.

  A basic concept of a two-wire load control device 1 according to an embodiment of the present invention will be described with reference to FIG. The load control device 1 is connected in series with a commercial power source 2 and a load 3. The load control device 1 includes a main opening / closing part 11 and an auxiliary opening / closing part 17 that control ON / OFF of the load 3 and a control part 13 that controls conduction of the main opening / closing part 11 and the auxiliary opening / closing part 17 in the same manner as the conventional example. And a power supply circuit for supplying drive power to the control unit 13. The power supply circuit includes a rectifying unit 12, a first power supply unit 14 that stabilizes power supply to the control unit 13, a second power supply unit 15 that supplies power to the first power supply unit 14 when power to the load 3 is stopped, and a load 3 includes a third power supply unit 16 that supplies power to the first power supply unit 14 when power is supplied to the power supply 3. The main opening / closing part 11 includes a triac 11a as a main switch element. Moreover, the auxiliary | assistant opening / closing part 17 is provided with the thyristor 17a as a switch element, for example, and the thyristor 17a is connected between the output terminals of the rectification | straightening part 12 comprised by the diode bridge. The first power supply unit 14 is a DC / DC converter that steps down the input direct current so that the output voltage is lower than the input voltage. Note that the configurations and operations of the second power supply unit 15 and the third power supply unit 16 are the same as those in the conventional example, and thus the description thereof is omitted.

  When the operation handle (SW) 4 for activating the load 3 is operated, the control unit 13 outputs a control signal, whereby the switch element 16c of the third power supply unit 16 is turned on, and the switch element 16b is turned on. To do. As a result, the current output from the rectifying unit 12 flows through the switch element 16 b and charges the buffer capacitor 18. When the buffer capacitor 18 is charged, the current flows through the Zener diode 16a to the gate of the thyristor 17a of the auxiliary opening / closing part 17, thereby making the thyristor 17a conductive. Since the thyristor 17a is connected between the output terminals of the rectifier unit 12, the current rectified by the rectifier unit 12 flows to the load 3 due to the conduction of the thyristor 17a. Since this current also flows through the gate of the triac 11a of the main switching unit 11, when the voltage becomes higher than the trigger voltage of the triac 11a, the triac 11a, that is, the main switching unit 11 becomes conductive. Once the main opening / closing part 11 becomes conductive (closed state), the current continues to flow. However, when the commercial current reaches the zero cross point, the triac 11a self-extinguishes and the main opening / closing part 11 becomes non-conductive (open state). Become. When the main opening / closing part 11 becomes non-conductive (open state), a current flows from the rectifying part 12 through the third power supply part 16 to the first power supply part 14, and the operation for securing the self-circuit power supply of the load control device 1 is performed. In other words, the self-circuit power supply securing of the load control device 1, the conduction of the auxiliary switching unit 17, and the conduction operation of the main switching unit 11 are repeated every half cycle of AC.

  The load control device 1 includes a noise filter 19 for removing burst noise on the side closer to the commercial power supply 2 and the load 3 than the main switching unit 11. The noise filter 19 includes a diode bridge 191 for rectifying the commercial power supply 2, a capacitor 192 connected between the positive electrode and the negative electrode of the output terminal of the diode bridge 191, a zener diode 193 connected in parallel to the capacitor 192, and a resistor It consists of a body 194 and the like. That is, the capacitor 192 constituting the noise filter 19 is provided in a DC system by the diode bridge 191. Even if the critical off voltage rises due to burst noise superimposed on the commercial power source 2, the charge caused by it is charged in the capacitor 192. When the electric charge is accumulated in the capacitor 192, current flows through the resistor 194 via the Zener diode 193 and is gradually consumed. Therefore, the leakage current from the capacitor 192 does not flow through the load 3, and the load 3 does not malfunction due to, for example, LED lighting due to burst noise. Note that in the case where the capacitance of the capacitor 192 can be increased, the Zener diode 193 and the resistor 194 may be omitted. Alternatively, when the internal resistance of the Zener diode 193 is large, the resistor 194 may be omitted. As the burst noise, for example, 1 MHz band noise is assumed, and the capacitance of the capacitor 192 corresponds to that.

  In this way, by providing the noise filter 19 of the DC system for removing burst noise on the side closer to the commercial power source 2 and the load 3 than the main switching unit 11, the current caused by the burst noise superimposed on the commercial power source 2 is the main current. The opening / closing part 11 almost does not flow through the auxiliary opening / closing part 17, and the triac 11a and the thyristor 17a do not conduct by mistake. Further, since the noise filter 19 is a DC system, no leakage current flows through the load 3 and no malfunction of the load 3 due to burst noise occurs.

  In the above embodiment, a full-wave rectifier circuit is used as the rectifier 12, but the present invention is not limited to this, and a half-wave rectifier circuit may be used. When the rectification unit 12 is a half-wave rectification circuit, two sets of the half-wave rectification circuit and the second power supply unit are prepared, the two sets of half-wave rectification circuit and the second power supply unit are connected in parallel, and the currents flowing in the respective circuits The same effect can be obtained even if the phase is shifted by 1/2 period.

DESCRIPTION OF SYMBOLS 1 Load control apparatus 2 Commercial power supply 3 Load 11 Main switching part 11a Triac (main switch element)
12 Rectifier 14 First Power Supply 15 Second Power Supply 16 Third Power Supply 17 Auxiliary Open / Close 17a Thyristor (Switch Element)
19 Noise Filter 191 Diode Bridge 192 Capacitor 193 Zener Diode 194 Resistor

Claims (4)

  Connected in series between the commercial power source and the load, and when the load is energized, after the auxiliary opening and closing part that is conducted first, and the auxiliary opening and closing part is conducted, it is more stable on the side closer to the load than the auxiliary opening and closing part A main switching unit for supplying the power and a power source unit for securing its own operating power, provided closer to the commercial power source and the load than the main switching unit, and superimposed on the commercial power source A two-wire load control device, further comprising a DC system noise filter for removing noise. A main opening and closing section for connecting a main electrode of a main switch element in series with a commercial power source and a load, and controlling supply of electric power to the load;
A rectifier connected between the main electrodes of the main switch element;
A control unit that controls on or off of the load according to an external signal;
A first power supply unit for stably supplying power to the control unit;
A second power supply unit that is supplied with power from both ends of the main opening / closing unit via a rectification unit and supplies power to the first power supply unit when the load is turned off;
A third power supply unit that is supplied with power from both ends of the main opening / closing unit via a rectification unit and supplies power to the first power supply unit when the load is turned on;
An auxiliary opening / closing portion connected between output terminals of the rectifying portion and conducting before the main opening / closing portion when supplying power to the load;
The auxiliary switching unit uses a thyristor as a switching element, the main switching unit uses a triac as the main switching element, is provided closer to the commercial power supply and the load than the main switching unit, and is superimposed on the commercial power supply A two-wire load control apparatus, further comprising a DC system noise filter for removing noise.   The two-wire load control device according to claim 1, wherein the noise filter includes a diode bridge and a capacitor connected to the diode bridge.   The two-wire load control device according to claim 3, wherein the noise filter includes a Zener diode connected in parallel to the capacitor.

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