JP5830659B2 - Load control device - Google Patents

Description

  The present invention relates to a two-wire load control device, and more particularly to a power supply unit for securing the internal power supply 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. Thus, in a load control device connected in series between a commercial power supply and a load, how to secure its own circuit power supply becomes a problem.

  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 power supply circuit includes a rectification unit 52, a first power supply unit 54 that stably supplies power to the control unit 53, a second power supply unit 55 that supplies power to the first power supply unit 54 when the load 3 is stopped, The third power source unit 56 supplies power to the first power source unit 54 when power is supplied to the load 3.

  The second power supply unit 55 is a constant voltage circuit (bootstrap circuit) configured by, for example, a resistor that limits current and a Zener diode (constant voltage diode) 55a that clamps a voltage, a transistor 55b, and the like. Wave rectified pulsating flow is input. The voltage waveform of the output from the second power supply unit 55 is substantially trapezoidal due to the Zener voltage of the Zener diode 55a. A part of the current output from the second power supply unit 55 flows to the first power supply unit 54 and is supplied as power of the control unit 53, and is connected to a buffer capacitor (capacitor) connected between the input terminals of the first power supply unit 54. ) Charge 58. When the voltage of the pulsating current that has been full-wave rectified by the rectifying unit 52 is lower than the Zener voltage, the buffer capacitor 58 serves as a power source and supplies power to the first power source unit 54. Therefore, the buffer capacitor 58 is repeatedly charged and discharged. In other words, a current flows through the load 3 via the Zener diode 55a and the rectifier 52 even when the load 3 is originally in an off state. The current flowing through the load 3 at that time must be a very small current that does not cause the load 3 to malfunction, and is set so that the current consumption of the control unit 53 is reduced and the impedance of the second power supply unit 55 is maintained high. ing.

  On the other hand, 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 as a result, the buffer capacitor 58 is charged. When the buffer capacitor 58 is charged, current flows in the order of the Zener diode 56 a, the thyristor 57 a of the auxiliary opening / closing part 57, and the triac 51 a of the main opening / closing part 51. When the triac 51a is turned on, the rectified voltage of the rectifying unit 52 becomes substantially zero, so that the second power supply unit 55 becomes non-conductive and no current flows. The same applies to the third power supply unit 56.

  Since the first power supply unit 54 is supplied with power from the buffer capacitor 58 while the second power supply unit 55 and the third power supply unit 56 are non-conductive, the input voltage of the first power supply unit 54, that is, the terminal of the buffer capacitor 58. The voltage gradually decreases. When the current flowing through the triac 51a becomes zero, the triac 51a is opened (non-conducting) by self-extinguishing, and a voltage is generated in the rectifying unit 52. When this voltage becomes higher than the terminal voltage of the buffer capacitor 58, the buffer capacitor 58 starts to be charged. Since the impedance of the second power supply unit 55 is set to be sufficiently higher than the impedance of the third power supply unit 56, the second power supply unit 55 operates the load control device 50 when the load 3 is on. Does not contribute.

  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 again from the rectifying part 52 through the third power supply part 56 to the first power supply part 54, and the 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, replacement with LED bulbs or the like is being promoted from the viewpoint of reducing power consumption. As is well known, the power consumption of LED bulbs is very small for load control devices. Therefore, when an LED bulb is connected to the load control device 50, a current flowing through the second power supply unit 55 flows to the LED bulb in order to secure an internal power source of the load control device 50 in a state where the load should be off. The LED bulb may light up. Therefore, it is important to reduce the current flowing through the second power supply unit 55 as much as possible when the load is off.

  As described above, the voltage input from the second power supply unit 55 or the third power supply unit 56 to the first power supply unit 54 fluctuates, whereas the control unit 53 configured by a CPU or the like is driven at a constant voltage. The Therefore, the first power supply unit 54 includes, for example, a three-terminal regulator 54a as a voltage stabilization circuit. Due to the action of the three-terminal regulator 54 a, a constant voltage direct current is output from the first power supply unit 54. On the other hand, the three-terminal regulator 54a in the first power supply unit 54 drops an extra voltage in order to stabilize the voltage, but a product obtained by multiplying the difference voltage between the input voltage and the output voltage by the current flowing in the control unit 53. It is consumed as it is. In order to reduce the current flowing through the load 3 when the load 3 is off, the output voltage from the second power supply unit 55 is stabilized and brought close to the output voltage of the three-terminal regulator 54a. It is desirable to reduce power loss.

  The present invention has been made in order to solve the above-described problem of the conventional example. When the load is off, standby power (power consumption in the internal power supply) of the load control device is reduced, and power consumption such as an LED bulb is performed. An object of the present invention is to provide a two-wire load control device that can prevent a load malfunction (such as erroneous light emission of an LED bulb) even when a small load is connected.

A load control device according to an aspect of the present invention is connected in series between a commercial power supply and a load, and an off power supply unit for securing an internal power supply when the load is in an off state is rectified by a rectifier circuit. A voltage clamping circuit that clamps the pulsating voltage and outputs power having a substantially trapezoidal voltage waveform; and fills a portion of the valley of the substantially trapezoidal voltage waveform, It is composed of a smoothing circuit for outputting a power having a DC voltage equivalent to the bottom.

  The voltage clamp circuit includes noise suppression means for suppressing noise from being superimposed on the clamped substantially trapezoidal voltage waveform, and a valley portion of the substantially trapezoidal voltage waveform is caused by the action of the noise suppression means. It is preferable to further include a smoothing prevention means for preventing the ink from being almost completely filled.

The load control device according to another aspect of the present invention is connected in series between a commercial power source and a load, and a main electrode of a main switch element is connected in series to the commercial power source and the load, A main switching unit for controlling power supply, a rectification unit connected between main electrodes of the main switch element, a control unit for controlling on / off of a load in accordance with an external signal, and the control unit A first power supply unit for supplying power stably, and power is supplied from both ends of the main opening / closing unit via a rectification unit, and the power to the first power supply unit is turned off when the load is turned off. A second power supply unit that supplies power, and a third power supply unit that is supplied with power from both ends of the main opening / closing unit via a rectifying unit and supplies power to the first power supply unit when the load is turned on. With
The second power supply unit clamps the pulsating voltage rectified by the rectifying unit to output power having a substantially trapezoidal voltage waveform, and a valley portion of the substantially trapezoidal voltage waveform A smoothing circuit that outputs power having a DC voltage corresponding to the bottom of the buried valley portion,
The voltage clamp circuit is:
An NPN transistor element comprising a collector to which a pulsating current rectified by the rectifying unit is input, a base connected to the collector via a feedback resistor, and an emitter for outputting electric power having the substantially trapezoidal voltage waveform When,
A Zener diode that has a cathode connected to the base side of the NPN transistor element, an anode connected to the ground, and determines a voltage for clamping the pulsating current;
A noise suppression capacitor connected between the cathode of the Zener diode and the ground and suppressing noise superimposed on the clamped substantially trapezoidal voltage waveform;
A cathode is connected to the cathode of the Zener diode, an anode is connected to the base of the NPN transistor element, and a valley portion of the substantially trapezoidal voltage waveform is almost completely filled by the action of the noise suppression capacitor. It is characterized by comprising a smoothing prevention diode for preventing the above.

  The smoothing circuit preferably includes a plurality of capacitors connected in series at the time of charging and connected in parallel at the time of discharging in order to fill a part of the valley portion of the substantially trapezoidal voltage waveform.

  According to the configuration of the present invention, the rectified pulsating voltage is clamped by the voltage clamp circuit of the off power supply unit (second power supply unit), and this clamp voltage becomes the peak voltage of the input voltage of the smoothing circuit. Furthermore, the valley filling function of the smoothing circuit fills a part of the valley portion of the substantially trapezoidal voltage waveform and superimposes the DC component. Then, a DC voltage corresponding to the bottom of the buried valley is output from the smoothing circuit. Therefore, compared with the off power supply unit of the conventional load control device, the voltage fluctuation of the power output from the off power supply unit is small, and the peak voltage is also low. Further, power loss due to a three-terminal regulator or the like is reduced, and standby power of the load control device in a state where the load is off can be reduced to prevent a malfunction of the load (such as erroneous light emission of the LED bulb).

1 is a circuit diagram showing a configuration of a two-wire load control device according to an embodiment of the present invention. The enlarged view which shows the detailed structure of the 2nd power supply part (off power supply part) in the said load control apparatus. The figure which shows the voltage waveform in each part of the said 2nd power supply part (off power supply part). The circuit diagram which shows the structure of the 2-wire type load control apparatus which concerns on a prior art example.

  A two-wire load control apparatus 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a circuit diagram showing a configuration of the two-wire load control device 1, and FIG. 2 is an enlarged view showing details of a second power supply unit (off power supply unit) 15 of the load control device 1. FIG. 3 is a voltage waveform diagram in each part of the second power supply unit (off power supply unit) 15.

  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 auxiliary opening / closing part 17 includes, for example, a thyristor 17a, and supplies a current of a magnitude necessary for conducting the TRIAC (main switching element) 11a of the main opening / closing part 11 to the gate of the main switching element. 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. Since the configuration other than the second power supply unit 15 is the same as that of the first conventional example, the description thereof is omitted.

  A pulsating current that has been full-wave rectified by the rectifying unit 12 is input to the input terminal P <b> 1 of the second power supply unit 15. The second power supply unit 15 clamps the input voltage and outputs power having a substantially trapezoidal voltage waveform, and smoothes and determines the substantially trapezoidal voltage waveform output from the voltage clamp circuit 15a. It has a smoothing circuit 15b that outputs DC power of voltage. As will be described later, the smoothing circuit 15b includes a first valley filling circuit 15c and a second valley filling circuit 15d.

  The voltage clamp circuit 15a includes an NPN transistor element 154, a Zener diode 155, a capacitor 156, and a diode 157. The collector 154c of the NPN transistor element 154 is connected to the rectifying unit 12, and a full-wave rectified pulsating current is input thereto. The base 154b of the NPN transistor element 154 is connected to the collector 154c via a feedback resistor 158. The cathode 155 c of the Zener diode 155 is connected to the base 154 b side of the NPN transistor element 154 via the diode 157. The anode 155a of the Zener diode 155 is connected (grounded) to the ground. The capacitor 156 is connected between the cathode 155c of the Zener diode 155 and the ground, and functions as a noise suppression capacitor that suppresses noise from being superimposed on a substantially trapezoidal voltage waveform clamped by the voltage clamp circuit 15a. . The cathode 157 c of the diode 157 is connected to the cathode 155 c of the Zener diode 155, and the anode 157 a is connected to the base 154 b of the NPN transistor element 154. The diode 157 functions as a smoothing prevention diode for preventing the valley portion of the continuous substantially trapezoidal voltage waveform from being almost completely filled by the action of the capacitor 156. The pulsating voltage that has been full-wave rectified by the rectifying unit 12 is clamped by the Zener voltage of the Zener diode 155, and electric power having a substantially trapezoidal voltage waveform is output from the emitter 154 e of the NPN transistor element 154. If necessary, the substantially trapezoidal voltage waveform may be referred to as “output voltage”.

  As is well known, a voltage clamp circuit can be configured with only the NPN transistor element 154, the Zener diode 155, and the feedback resistor 158 (see FIG. 4). However, due to the operating principle of the Zener diode 155, avalanche noise is superimposed on the clamped voltage waveform, and the top of the substantially trapezoidal voltage waveform is not smooth (assuming that the avalanche noise in FIG. 3 is superimposed). Refer to the waveform in the case of In general, therefore, avalanche noise can be reduced or eliminated by connecting a capacitor 156 in parallel with the Zener diode 155. On the other hand, the electric power having the substantially trapezoidal voltage waveform output from the voltage clamp circuit 15a is input to the first valley filling circuit 15c of the smoothing circuit 15b, and a part of the valley portion of the approximately trapezoidal voltage waveform. Are going to fill. However, if the capacitor 156 is simply connected in parallel with the Zener diode 155, most of the valley portion of the substantially trapezoidal voltage waveform is filled with the discharge from the capacitor 156. In the voltage clamp circuit 15a, since the diode 157 is connected between the NPN transistor element 154 and the Zener diode 155, the capacitor 156 does not discharge the valley portion of the substantially trapezoidal voltage waveform. As a result, electric power having a substantially trapezoidal voltage waveform in which the top is smoothed and the valley is not filled is output from the voltage clamp circuit 15a (see the voltage clamp circuit output voltage waveform in FIG. 3). ).

  The first valley filling circuit 15c of the smoothing circuit 15b includes a plurality of (for example, three) first capacitors 151a to 151c and a plurality of diodes 152a to 152g connected between terminals of the first capacitors 151a to 151c. ing. Further, the second valley filling circuit 15 d is configured by a single second capacitor 159. A switch element (FET) 153 is connected between the first valley filling circuit 15c and the second valley filling circuit 15d. The control electrode (the gate electrode of the FET) of the switch element 153 is connected to the voltage clamp circuit 15a. The output voltage is applied. As shown in FIG. 3, the voltage clamp circuit 15a outputs power having a substantially trapezoidal voltage waveform in which the top is smoothed and the valley is not filled (that is, has a zero-cross point). Is done.

  The switch element 153 is turned on (closed state) when the output voltage of the voltage clamp circuit 15a is lower than the output voltage of the first valley filling circuit 15c and the potential difference becomes equal to or higher than the trigger voltage of the switch element 153. . However, immediately after the load control device 1 is installed and connected to the commercial power supply 2, the first capacitors 151a to 151c of the first valley filling circuit 15c are not charged, so the switch element 153 is turned off (open state). It is. When the voltage between both terminals of the first capacitors 151a to 151c of the first valley filling circuit 15c exceeds the output voltage of the voltage clamp circuit 15a, and the discharge is started from these first capacitors 151a to 151c, the switching element 153 is the first time. Turns on (closed). The peak voltage of the substantially trapezoidal voltage waveform is defined as a clamp voltage Vc.

  When the switch element 153 is turned on, the electric power discharged from the first capacitors 151a to 151c of the first valley filling circuit 15c is output from the output terminal P3 of the second power supply unit 15. When the output voltage of the first valley filling circuit 15c rises and reaches the pinch-off voltage of the switch element 153, the switch element 153 is turned off (open state), and the output from the first valley filling circuit 15c is supplied to the second power supply unit. 15 is not output from the output terminal P3. Instead, the electric power discharged from the second capacitor 159 of the second valley filling circuit 15d is output from the output terminal P3 of the second power supply unit 15. On the other hand, the first capacitors 151a to 151c of the first valley filling circuit 15c are charged. During the charging of the first capacitors 151a to 151c, the peak voltage of the substantially trapezoidal voltage waveform is maintained for a certain time, so that the first capacitors 151a to 151c are almost fully charged. Since the first capacitors 151a to 151c are connected in series during charging, in this case, the terminal voltages of the first capacitors 151a to 151c are Vc / 3. The second capacitor 159 of the second valley filling circuit 15d may be applied with a voltage equal to or higher than the pinch-off voltage of the switch element 153 due to a delay in time when the switch element 153 is turned off. The second capacitor 159 of the valley filling circuit 15d repeats voltage reduction and recovery in a half-wave period with the pinch-off voltage as a peak.

  As described above, the first capacitors 151a to 151c of the first valley filling circuit 15c and the second capacitor 159 of the second valley filling circuit 15d are repeatedly charged and discharged, thereby causing zero crossing from the output terminal P3 of the second power supply unit 15. Electric power having a flat voltage waveform with no noise is output. In addition, by appropriately selecting the pinch-off voltage of the switch element 153 and the capacitance of the second capacitor 159, the output voltage from the second power supply unit 15 when the switch element 153 is off (open state) is reduced. A DC voltage corresponding to the bottom of the part can be obtained. For example, if the pinch-off voltage of the switch element 153 is set to a voltage slightly higher than Vc / 3, a voltage higher than the pinch-off voltage is not applied to the second capacitor 159. Therefore, the output voltage variation from the second power supply unit 15 is not changed. Can be reduced.

  As can be seen from the above description, it can be said that the off power supply unit in the load control device of the present invention is obtained by inserting a smoothing capacitor and a backflow prevention diode into a bootstrap circuit of a transistor.

  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 Two-wire type load control apparatus 2 Commercial power supply 3 Load 11 Main switching part 12 Rectifier 14 First power supply 15 Second power supply 15a Voltage clamp circuit 15b Smoothing circuit 15c First valley filling circuit 15d Second valley filling circuit 16 3rd power supply part 17 Auxiliary opening-and-closing part 151a-151c 1st capacitor 152a-152g Diode 153 Switch element 154 NPN transistor element 155 Zener diode 156 Capacitor (noise suppression capacitor)
157 Diode (anti-smoothing diode)
158 Feedback resistor 159 Second capacitor

Claims (3)

An off power supply unit connected in series between a commercial power supply and a load and securing an internal power supply when the load is in an off state clamps a pulsating voltage rectified by a rectifier circuit and has a substantially trapezoidal shape. A voltage clamp circuit that outputs power having a voltage waveform and a part of the valley portion of the substantially trapezoidal voltage waveform are filled, and power having a DC voltage corresponding to the bottom of the buried valley portion is outputted. A load control device configured by a smoothing circuit ,
The voltage clamp circuit includes noise suppression means for suppressing noise from being superimposed on the clamped substantially trapezoidal voltage waveform, and a valley portion of the substantially trapezoidal voltage waveform is caused by the action of the noise suppression means. A load control apparatus , further comprising a smoothing prevention means for preventing substantially completely filling . A main switching unit that is connected in series between a commercial power source and a load, a main electrode of a main switch element is connected in series to the commercial power source and the load, and controls the 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 or off of a load according to a signal from the outside,
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 load control device including 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. And
The second power supply unit clamps the pulsating voltage rectified by the rectifying unit to output power having a substantially trapezoidal voltage waveform, and a valley portion of the substantially trapezoidal voltage waveform A smoothing circuit that outputs power having a DC voltage corresponding to the bottom of the buried valley portion,
The voltage clamp circuit is:
An NPN transistor element comprising a collector to which a pulsating current rectified by the rectifying unit is input, a base connected to the collector via a feedback resistor, and an emitter for outputting electric power having the substantially trapezoidal voltage waveform When,
A Zener diode that has a cathode connected to the base side of the NPN transistor element, an anode connected to the ground, and determines a voltage for clamping the pulsating current;
A noise suppression capacitor connected between the cathode of the Zener diode and the ground and suppressing noise superimposed on the clamped substantially trapezoidal voltage waveform;
A cathode is connected to the cathode of the Zener diode, an anode is connected to the base of the NPN transistor element, and a valley portion of the substantially trapezoidal voltage waveform is almost completely filled by the action of the noise suppression capacitor. A load control device comprising a smoothing prevention diode for preventing the above. 3. The smoothing circuit includes a plurality of capacitors connected in series at the time of charging and connected in parallel at the time of discharging in order to fill a part of a valley portion of the substantially trapezoidal voltage waveform. The load control device described in 1 .

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