JP2007174575A - Two-wire electronic switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-wire electronic switch capable of stably ensuring its own operating power supply even when a temperature of a load switching section is remarkably increased. <P>SOLUTION: A gate current of the triac (load switching section) 1 decreases at a high temperature and increases at a low temperature. The resistance of a temperature sensing resistor 8 decreases when the triac 1 reaches the high temperature and increases when the triac 1 gets the low temperature. When a control signal of a control section 3 goes up to a high level, a third power supply section 6 is turned on to supply power to a first power supply section 4. Thereafter, when a cathode level of a Zener diode 72 is higher than a Zener voltage, a thyristor 70 is turned on by a gate current from a thyristor drive section 71 and a load current flows from a rectifier section 2 to the thyristor 70. The temperature sensing resistor 8 establishes a resistance in response to the temperature of the triac 1 thereafter so that a timing of turning on the triac 1 may be constant and brings the triac 1 into an on state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a two-wire electronic switch for turning on and off the power supply from an AC power supply to a load, and it is necessary to secure an operating power supply by itself.

  Conventionally, as a switch to turn on / off the power supply from the AC power supply to the load, a non-contact switching element such as a thyristor or a triac is inserted into the power supply path from the AC power supply to the load as a load switching unit with the digitization of the wiring equipment. However, there is provided a type (first conventional switch) that electrically opens and closes (turns on and off) the contactless switching element using an electronic circuit. The first conventional switch needs to secure its own operating power supply (circuit power supply) because the electronic circuit drives the non-contact switching element when a person operates the operation unit (operation switch). Therefore, the first conventional switch has a configuration in which wiring is performed by three lines or four lines.

  However, from the viewpoint of reduced wiring, when a two-wire wiring is a general wiring device, the first conventional switch cannot individually draw in the power source wire when connected to the AC power source and the load by the two wires. As a result, securing a self-operating power supply became a problem.

  In order to solve the above problem, a two-wire electronic switch (2 wire electronic switch that enables two-wire wiring in a state in which a contactless switching element is used as a load switching unit while being connected in series with an AC power source and a load. A second conventional switch) has been proposed. A configuration almost similar to that of the second conventional switch is disclosed in Patent Document 1.

  The operation of the second conventional switch will be described with reference to FIG. FIG. 3 is a circuit diagram of a second conventional switch. In the second conventional switch 9, a triac 90 as a load switching unit is connected in series with the AC power source AC and the load L. First, when the control signal from the control output terminal 910 of the control unit 91 becomes low level, the third power supply unit 92 is turned off. At this time, the second power supply unit 93 supplies power to the first power supply unit 94. In this state, the gate current (drive signal) of a magnitude necessary to turn on the triac 90 does not flow through the gate (drive signal input terminal) of the triac 90, so the triac 90 is turned off (opened). The power supply from the AC power supply AC to the load L is cut off.

On the other hand, when the control signal from the control output terminal 910 of the control unit 91 becomes a high level, the third power supply unit 92 is turned on. As a result, the third power supply unit 92 supplies power to the first power supply unit 94. At this time, when the charging of the first power supply unit 94 is completed, a current flows from the charging completion detection unit 920 to the auxiliary opening / closing unit 95, and the auxiliary opening / closing unit 95 is turned on (closed). When the auxiliary opening / closing unit 95 is turned on, a current having a magnitude necessary for turning on the triac 90 flows to the triac drive unit 96, and a gate current flows from the triac drive unit 96 to the triac 90. Thus, the triac 90 is turned on (closed), and power is supplied from the AC power supply AC to the load L.
JP 2001-227804 A (pages 2 to 5 and FIG. 7)

  However, the second conventional switch 9 is used when a load with a large rated current is connected to increase the load current flowing through the load or when the heat is not sufficiently dissipated by being disposed in a narrow space, There has been a problem that the sensitivity of the load opening / closing section changes due to an increase in temperature of the load opening / closing section (triac 90). More specifically, the temperature rises due to the material characteristics of the load opening / closing part, the drive signal becomes small, and the sensitivity of the load opening / closing part becomes high. In a state where the sensitivity of the load switching unit is high, the electrical switching of the load switching unit is switched by the drive signal from the triac driving unit 96 during charging of the first power supply unit 94. As a result, the first power supply unit 94 becomes insufficiently charged and the control unit 91 stops, so that it becomes difficult to stably secure its own operating power supply.

  The present invention has been made in view of the above points, and its object is to stably secure its own operating power supply even when the temperature rise of the load switching unit becomes large. An object of the present invention is to provide a two-wire electronic switch capable of

  The invention according to claim 1 is a two-wire electronic switch that is connected to an AC power source and a load by two wires and secures its own operating power source based on the AC power from the AC power source. A load switching unit that is inserted into a power supply path to the load and has a temperature dependency on an amplitude value of a drive signal when electrical switching between both ends is switched, and operates with power based on the AC power, and the load switching A control unit that outputs a control signal for controlling power supply from the AC power source to the load by switching the electrical opening and closing of the unit, and performs the power supply from the AC power source to the load based on the control signal Sometimes, the drive unit that controls the drive signal and outputs it to the load switching unit so that the switching timing of the electrical switching of the load switching unit is constant with respect to the temperature change of the load switching unit. To prepare And features.

  In this configuration, even when the temperature rise of the load switching unit becomes large, the drive signal is controlled so that the switching timing of the electrical switching of the load switching unit is constant with respect to the temperature change of the load switching unit. Therefore, it is possible to reduce the switching of the electrical switching of the load switching unit before securing the operating power supply of the two-wire electronic switch, and it is possible to stably secure the operating power supply.

  According to a second aspect of the present invention, in the first aspect of the present invention, the drive unit is connected to a drive signal input end of the load switching unit at one end and one of the both ends of the load switching unit at the other end. It is a temperature sensitive resistor connected to In this configuration, by using the temperature sensitive resistor, the switching timing of the electrical switching of the load switching unit can be made constant with respect to the temperature change of the load switching unit with a small size and low cost.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the first power supply unit serving as an operation power supply for the control unit and the load opening / closing unit are in an open state from the AC power supply. When the power supply to the load is stopped, a second power supply unit that supplies power converted from the AC power to the first power supply unit, and the AC power based on the control signal A third power supply unit that supplies the converted power to the first power supply unit and the drive unit are electrically connected in series, and power is supplied from the third power supply unit to the first power supply unit. When the input voltage of the first power supply unit becomes higher than a predetermined voltage value, the closed state is entered, thereby causing the drive unit to control the drive signal and causing the load switching unit to And an auxiliary opening / closing section for outputting. In this configuration, the first power supply unit, the second power supply unit, the third power supply unit, and the auxiliary opening / closing unit can reliably supply power to the control unit, and can reliably supply a drive signal to the drive unit. Can be controlled.

  According to the present invention, even when the temperature rise of the load switching unit becomes large, it is possible to reduce the switching of the electrical switching of the load switching unit before securing the operating power supply of the two-wire electronic switch. The operation power supply can be secured stably.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a circuit diagram of the two-wire electronic switch of this embodiment. FIG. 2 shows the temperature dependence of the triac in the two-wire electronic switch of this embodiment, where (a) shows a measurement circuit diagram, (b) shows a gate current, and (c) shows a gate voltage. is there.

  First, the basic configuration of this embodiment will be described. The two-wire electronic switch A of the present embodiment secures its own operating power source based on AC power from the AC power source AC. As shown in FIG. 1, the triac 1, the rectifying unit 2, and the control Unit 3, first power supply unit 4, second power supply unit 5, third power supply unit 6, auxiliary opening / closing unit 7, and temperature sensitive resistor 8, and in series with AC power supply AC and load L Are connected with two wires. The AC power supply AC is, for example, a commercial power supply of 100V. The load L is, for example, a lighting device including a fluorescent lamp or an incandescent bulb, a ventilation fan, or the like.

  The triac 1 is a load switching unit that is formed of a semiconductor such as silicon and switches electrical switching between the two terminals 10 and 11 in accordance with a gate current (drive signal). The TRIAC 1 is connected in series with an AC power source AC and a load L via terminals 12 and 13 and a filter inductor 14. The triac 1 and the inductor 14 are connected in parallel with the surge absorbing element 15 and the filter capacitor 16, respectively. In the present embodiment, when the triac 1 is turned on (closed), the circuit is made up of the AC power supply AC, the triac 1, the inductor 14, and the load L, power is supplied to the load L, and the load L operates. On the other hand, when the triac 1 is turned off (opened), power is not supplied to the load L, and the operation of the load L is stopped.

By the way, the triac 1 has temperature dependency on the amplitude values of the gate current and the gate voltage when the electrical switching between the two terminals 10 and 11 is switched. Specifically, to measure the gate current I _GT and the gate voltage V _GT switched electrical opening and closing of the triac 1 using a measuring circuit as shown in FIG. 2 (a). FIG. 2B shows values normalized by the gate current at 25 ° C., and FIG. 2C shows values normalized by the gate voltage at 25 ° C. As shown in FIG. 2B, the gate current _IGT decreases as the temperature increases, and increases as the temperature decreases. The gate voltage V _GT, as shown in FIG. 2 (c), decreases the high temperatures, higher becomes the low temperature. From the above, the sensitivity of the triac 1 increases as the temperature increases. That is, it turns on with a small gate current or a low gate voltage. On the other hand, when the temperature is lowered, the sensitivity is lowered, and a large gate current and a high gate voltage are required for turning on.

  As shown in FIG. 1, the rectifying unit 2 is a diode bridge composed of four diodes, and is connected to the AC power source AC and the load L via terminals 12 and 13 at the input end and the second power source unit at the output end. 5, connected to the third power supply unit 6 and the auxiliary opening / closing unit 7. The rectifying unit 2 performs full-wave rectification on the AC power from the AC power supply AC, and outputs the full-wave rectified power to the second power supply unit 5, the third power supply unit 6, and the auxiliary opening / closing unit 7.

  The control unit 3 is a microcomputer that outputs a control signal for switching electrical opening / closing of the triac 1 from the control output terminal 30 to the third power supply unit 6 by, for example, a human operation. The control unit 3 operates with electric power from the first power supply unit 4. In addition, the control unit 3 is provided with an operation unit (operation switch) (not shown) such as a tact switch, which is operated by a person, and the control signal is output every time the operation unit is operated. 3 to the power supply unit 6. The control signal is a binary signal having a high level and a low level. The control unit 3 outputs a high level control signal when the triac 1 is turned on, and when the triac 1 is turned off. Outputs a low level control signal. Thereby, the control unit 3 controls power supply from the AC power supply AC to the load L.

  The first power supply unit 4 is an operation power supply for the control unit 3, and includes a buffer capacitor 40, a three-terminal regulator 41, a capacitor 42, and a capacitor 43 connected in parallel from the input end side. The input end is connected to the second power supply unit 5 and the third power supply unit 6, and the output end is connected to the input end of the control unit 3. The buffer capacitor 40 is charged with power from the second power supply unit 5 and the third power supply unit 6 and smoothed by removing ripple components. The three-terminal regulator 41 stabilizes the direct-current voltage of the buffer capacitor 40 to, for example, 3V. From the above, the first power supply unit 4 supplies stable power to the control unit 3.

  The second power supply unit 5 includes, in order from the input end side, a current-limiting resistor 50, an NPN transistor 51, and a resistor 52 connected in series, and is connected to the output end of the rectifying unit 2 at the input end. In addition, the first power supply unit 4 is connected on the output end side. The second power supply unit 5 includes a bias resistor 53 connected between the base and collector of the transistor 51, and a Zener diode 54 whose cathode is connected to the base of the transistor 51. The base of the transistor 51 is grounded via a Zener diode 54. The impedance conversion of the second power supply unit 5 is performed according to the on state and the off state of the transistor 51. The second power supply unit 5 supplies AC power from the AC power supply AC via the rectifying unit 2 when the triac 1 is turned off and power supply from the AC power supply AC to the load L is stopped. The power is received as full-wave rectified power, is converted into power whose size is regulated by the Zener diode 54, and the converted power is supplied to the first power supply unit 4. At this time, the load current in the two-wire electronic switch A is divided into a current flowing through the first power supply unit 4 and a current flowing through the Zener diode 54, both of which are finally connected to the rectifying unit via the ground. 2 and returns to the AC power source AC via the load L. The load current at this time is large enough to prevent the load L from malfunctioning. Further, the current consumption of the control unit 3 is kept low, and the impedance of the second power supply unit 5 is kept high.

  The third power supply unit 6 includes, in order from the input end side, a PNP transistor 60 and a diode 61 connected in series. The third power supply unit 6 is connected to the output end of the rectifying unit 2 at the input end and the first at the output end. Is connected to the power supply unit 4 of That is, the third power supply unit 6 is connected in parallel with the second power supply unit 5. The third power supply unit 6 includes a resistor 62 and a capacitor 63 connected between the base and emitter of the transistor 60, and a resistor 64 and an NPN transistor 65 connected to the base of the transistor 60. Further, the third power supply unit 6 includes a resistor 66 connected between the base and emitter of the transistor 65. The transistor 65 has an emitter grounded and a base connected to the control output terminal 30 of the control unit 3. The transistor 65 controls the on / off state of the transistor 60. The third power source unit 6 receives AC power from the AC power source AC as full-wave rectified power via the rectifying unit 2 based on a control signal from the control unit 3, and receives the power from the first power source AC. Supply to the power supply unit 4. A specific procedure will be described. When a high-level control signal is received from the control unit 3, the transistor 65 is turned on. Accordingly, the transistor 60 is turned on. At this time, the impedance of the two-wire electronic switch A decreases. Thereafter, the third power supply unit 6 supplies power to the first power supply unit 4. In contrast, when a low level control signal is received from the control unit 3, the transistor 65 is turned off and the transistor 60 is also turned off. As a result, the third power supply unit 6 stops supplying power to the first power supply unit 4.

  The auxiliary opening / closing unit 7 includes a thyristor 70 and a thyristor driving unit 71. The thyristor 70 is connected to the output terminal of the rectifying unit 2 and is also connected to the input terminals of the second power supply unit 5 and the third power supply unit 6. On the other hand, the thyristor driving unit 71 includes a resistor 710 and a capacitor 711 connected in parallel, one end connected to the gate of the thyristor 70 and the Zener diode 72, and the other end connected to the cathode of the thyristor 70. The zener diode 72 is connected to the DC voltage of the buffer capacitor 40 of the first power supply unit 4 when the power is supplied from the third power supply unit 6 to the first power supply unit 4. When the input voltage becomes higher and the cathode potential becomes higher than the zener voltage, the charging completion detection unit detects that the charging of the first power supply unit 4 is completed by flowing a reverse current to the thyristor driving unit 71. . When a reverse current flows from the Zener diode 72, the thyristor driving unit 71 causes a gate current of a magnitude necessary to turn on the thyristor 70 to flow through the thyristor 70 for a certain period. As a result, the load current flowing from the rectifying unit 2 to the third power supply unit 6 flows from the rectifying unit 2 to the thyristor 70, and the auxiliary opening / closing unit 7 is necessary to turn on the triac 1 with respect to the temperature-sensitive resistor 8. Control is performed so that a large amount of gate current flows through the triac 1.

  The temperature-sensitive resistor 8 is connected to the gate (drive signal input terminal) of the triac 1 at one end and to the terminal 11 of the triac 1 at the other end. Further, the temperature sensitive resistor 8 is connected in series with the thyristor 70 of the auxiliary opening / closing unit 7 through the rectifying unit 2. The temperature-sensitive resistor 8 is a drive unit that causes a flowing current to increase when the thyristor 70 is turned on, and causes a gate current of a magnitude necessary to turn on the triac 1 to flow to the gate of the triac 1.

  By the way, the temperature sensitive resistor 8 is an NTC thermistor, for example, and monitors the temperature rise of the triac 1, and the resistance value changes according to the temperature of the triac 1. Specifically, the temperature-sensitive resistor 8 decreases in resistance value when the temperature of the triac 1 increases and increases the flowing current. On the contrary, when the temperature of the TRIAC 1 decreases, the resistance value increases and the flowing current is reduced. Such a temperature sensitive resistor 8 controls the gate current so that the turn-on timing of the triac 1 is constant with respect to the temperature change of the triac 1. This prevents the load current in the two-wire electronic switch A from being too small when the triac 1 is turned on and turned on even if the triac 1 becomes highly sensitive due to temperature rise.

  Next, the operation of the two-wire electronic switch A of this embodiment will be described. First, an operation in a state where the power supply from the AC power supply AC to the load L is not performed (off state) will be described. When the control signal of the control unit 3 becomes low level, the transistor 65 and the transistor 60 of the third power supply unit 6 are turned off. On the other hand, the second power supply unit 5 supplies power to the first power supply unit 4. As a result, the first power supply unit 4 serves as an operating power supply for the control unit 3. In this state, since the gate current of a magnitude necessary for turning on the triac 1 does not flow through the gate of the triac 1, the triac 1 is turned off and operates from the AC power supply AC to the load L. Insufficient power is supplied.

  Subsequently, an operation in a state where the power supply from the AC power supply AC to the load L is performed (on state) will be described. When the control signal of the control unit 3 becomes high level, the transistor 65 and the transistor 60 are turned on, and the third power supply unit 6 supplies power to the first power supply unit 4. As a result, the first power supply unit 4 serves as an operating power supply for the control unit 3. On the other hand, when the input voltage of the first power supply unit 4 increases and the cathode potential of the Zener diode 72 becomes higher than the Zener voltage, the Zener diode 72 causes a reverse current to flow to the thyristor driving unit 71. After that, the thyristor driving unit 71 passes a gate current of a magnitude necessary for turning on the thyristor 70 to the thyristor 70, and the thyristor 70 is turned on. As a result, the load current flowing from the rectifying unit 2 to the third power supply unit 6 flows from the rectifying unit 2 to the thyristor 70. Thereafter, the temperature-sensitive resistor 8 sets a resistance value corresponding to the temperature of the triac 1 so that the turn-on timing of the triac 1 is constant. The temperature sensitive resistor 8 causes a gate current of a magnitude necessary to turn on the triac 1 to flow to the gate of the triac 1, and the triac 1 is turned on. As described above, power is supplied from the AC power supply AC to the load L.

  Here, when the TRIAC 1 is turned on, a load current flows through the TRIAC 1. However, when the zero cross point is reached, the arc is turned off and turned off. When the triac 1 is turned off, a load current flows again from the rectifying unit 2 to the first power source unit 4 via the third power source unit 6, and an operating power source for the two-wire electronic switch A is secured, and a thyristor 70 is provided. And the operation to turn on the triac 1 is performed. That is, the operation of securing the operating power supply is performed every half cycle of the AC power from the AC power supply AC.

  As described above, according to the present embodiment, even when the temperature increase of the triac 1 becomes large, the temperature sensitive resistance is set so that the switching timing of the electrical opening and closing of the triac 1 is constant with respect to the temperature change of the triac 1. Since the resistance value of 8 can be changed, it is possible to reduce the triac 1 from being turned on and being turned on before securing the operating power supply of the two-wire electronic switch A, thereby stabilizing the operating power supply. Can be secured. Further, by using the temperature sensitive resistor 8, the switching timing of the electrical opening and closing of the triac 1 can be made constant with respect to the temperature with a small size and at a low cost. Furthermore, the first power supply unit 4, the second power supply unit 5, the third power supply unit 6, and the auxiliary opening / closing unit 7 can reliably supply power to the control unit 3, while Thus, the gate current can be controlled to flow through the triac 1 reliably.

  As a modification of the present embodiment, the load opening / closing unit may include a thyristor instead of the triac. Even with such a configuration, the same effects as in the present embodiment can be obtained.

  As another modification of the present embodiment, when the triac is turned on and when the triac is turned off, the control unit outputs a pulsed control signal to the third power supply unit, The power supply unit may supply power to the first power supply unit based on the control signal. Even with such a configuration, the same effects as in the present embodiment can be obtained.

1 is a circuit diagram of a two-wire electronic switch according to an embodiment of the present invention. The temperature dependence of the triac in the above two-wire electronic switch, (a) is a measurement circuit diagram, (b) is a diagram showing a gate current, (c) is a diagram showing a gate voltage. It is a circuit diagram of the conventional 2-wire type electronic switch.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Triac 2 Rectification part 3 Control part 4 1st power supply part 6 3rd power supply part 70 Thyristor 71 Thyristor drive part 72 Zener diode 8 Temperature sensitive resistance

Claims (3)

A two-wire electronic switch that is connected to an AC power source and a load with two wires and secures its own operating power source based on the AC power from the AC power source,
A load switching unit that is inserted into a power feeding path from the AC power source to the load and has a temperature dependency on an amplitude value of a drive signal when electrical switching between both ends is switched;
A controller that operates with power based on the AC power, and outputs a control signal that controls power supply from the AC power supply to the load by switching the electrical switching of the load switching unit;
When the power supply from the AC power source to the load is performed based on the control signal, the switching timing of the electrical switching of the load switching unit is constant with respect to the temperature change of the load switching unit. And a drive unit that controls the drive signal and outputs the drive signal to the load switching unit.   2. The temperature sensor according to claim 1, wherein the driving unit is connected to a driving signal input terminal of the load switching unit at one end and is connected to one of the both ends of the load switching unit at the other end. 2-wire electronic switch. A first power supply unit serving as an operation power supply for the control unit;
A second power source configured to supply power converted from the AC power to the first power source when the load switching unit is in an open state and the power supply from the AC power source to the load is stopped. A power supply,
A third power supply unit that supplies power converted from the AC power to the first power supply unit based on the control signal;
The input voltage of the first power supply unit is a predetermined voltage when the first power supply unit is electrically connected in series with the drive unit and power is supplied from the third power supply unit to the first power supply unit. The auxiliary opening / closing part which controls the driving signal to the driving part to output to the load opening / closing part by being in a closed state when the value becomes higher than the value. Wire electronic switch.

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