JPS63211925A - Impedance improving device - Google Patents

Abstract

PURPOSE:To prevent communication by connecting a coil and a capacitor in series and selecting combined impedance to be inductive at carrier frequencies thereby facilitating the insulation because of small size and blocking the signal. CONSTITUTION:A coil 13 and a capacitor 4 form a parallel resonance circuit to increase the impedance at the carrier frequencies thereby preventing the attenuation of the signal voltage. When the inductance of the coil 13 is selected to be 10muH and the capacitance of the capacitor 14 is selected to be 0.33muF, the series resonance frequency is 87.6kHz and the impedance is inductive at a carrier frequency of 125kHz of power line carrier communication. When the capacitance of the capacitor 4 of the device is selected to be 0.33muF, the impedance improving device 12 and the capacitor 4 cause parallel resonance at 125kHz, and the load impedance is infinite by a signal sent through a lighting line 2 to avoid the reduction in the signal voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an impedance improvement device for power line carrier communication.

Conventional technology Conventionally, as shown in Fig. 2, a transmitter (1) and a receiver (6) are used.
Connect 1 to the power line (2), and connect 1 to the power line (2).
In power line carrier communication, which performs communication within a home by superimposing carrier waves of 26 KHz, 165 KHz, etc., various electrical devices (3) are connected to a power line (2), which is a signal transmission path. Some of these are equipped with an across-the-line capacitor (4) to protect the equipment's circuits from external noise and to reduce the noise terminal voltage generated by the equipment. If this device is connected, the power line (2)
- inductance component and capacitor of equipment (3) (
4) causes resonance and there are places where the signal voltage is attenuated by +odB or more. For example, if the carrier frequency f is 125 KIH and the capacitance C of the capacitor (4) of the device (3) is 0.1 μF, the resonant inductance L is L = -= 16.2 CμH] (2πf)2C. The inductance of a power line is approximately 0.0 per 1ff1.
65#H, the signal voltage becomes almost zero 25 meters before the capacitor (4), and the signal no longer reaches the receiver 6 connected there. FIG. 3 shows the attenuation state of this signal voltage, with the horizontal axis showing the distance of the power line and the vertical axis showing the signal voltage.

Therefore, in order to reduce the influence of the capacitor (4) of the electrical equipment (3), impedance improvement devices 6 were connected in series as shown in FIG. Conventional impedance improvement device 6
In the circuit shown in FIG. 6, a constant coil 7 that resonates at the carrier frequency and a capacitor 8 are connected in parallel. By adding a resistance component generated by parallel resonance in series to the capacitance component of the capacitor 4 of the device, the reduction in resonance resistance with the inductive component 1o of the signal transmission path is suppressed, thereby preventing signal voltage attenuation. . Note that the resistor 11 lowers the Q of the resonance caused by the coil 7 and the capacitor 8, and reduces the influence of changes in the resonant frequency due to changes in inductance when a load current of the commercial frequency used by the electrical equipment 3 flows in the coil 7 in a superimposed manner. It is for the purpose of

Problems to be Solved by the Invention Although such a conventional impedance improvement device can reduce the attenuation of the communication signal voltage, if the load current of the electrical equipment is 16A, 15A also flows through the coil of the impedance improvement device. Therefore, those with large current capacity are
They generated a lot of heat and were large and expensive. In addition, it had to be installed in series with electrical equipment, and in particular, when installing electrical equipment, it was necessary to temporarily cut the power line wiring and attach an impedance improvement device. Furthermore, since the impedance improvement device has a high impedance with respect to the carrier frequency, communication by passing the impedance improvement device is impossible. This means, for example, that if you install a wall outlet through an impedance improvement device, you cannot use this outlet to communicate with another location.

The present invention has been made in view of these points, and an object of the present invention is to provide an impedance improvement device that is small, inexpensive, easy to install, and does not create a place where communication is impossible.

Means for Solving the Problems In order to solve the above problems, the present invention uses a coil and a capacitor connected in series, the combined impedance of which is selected as a constant that is inductive at the carrier frequency, to the power line. The capacitor is connected in parallel with the capacitor of the electrical equipment.

According to the above configuration, the present invention forms a parallel resonant circuit for a power line using a capacitor and an impedance improvement device for electrical equipment, increases the resistance component of the impedance at the carrier frequency, and reduces attenuation of the carrier signal. .

Embodiment FIG. 1 is a diagram showing an embodiment of the impedance improving device of the present invention. 1 is a transmitter, 2 is a power line, 3 is an electric device, 4 is a capacitor provided in the electric device, and 10 is an inductive component of a signal transmission path.

This is the same as the conventional one shown in FIG.

12 is an impedance improvement device connected in parallel with the capacitor 4 of the electrical equipment 3. This is to increase the impedance at the carrier frequency by forming a parallel resonant circuit with the coil 13 and the capacitor 4, thereby preventing attenuation of the signal voltage.

Note that the capacitor 1 connected in series with the coil 13
4 is for blocking the commercial frequency current and passing the high frequency carrier frequency. For example, the inductance of the coil 13 is 10 μH, and the capacitance of the capacitor 14 is 0.33 μH.
F, the series resonance frequency is 87.6KHz, and the carrier frequency of power line carrier communication is higher than 12f5KH.
It becomes inductive at z.

If the capacitance of the capacitor 4 of the device is 0.33μF, the impedance improvement device 12 and the capacitor 4 cause parallel resonance at 125K)lz, and the power line 2
The load impedance becomes infinite for the signal transmitted, and there is no drop in the signal voltage. Also, since the across-the-line capacitor 4 used in electrical equipment is usually 0.1 μF or less, the impedance improvement device 1
The parallel impedance due to capacitor 2 and capacitor 4 is inductive. If the combined load impedance is inductive, a point where the signal voltage becomes zero due to resonance with the inductance 10 of the power line will not occur, and communication failures can be eliminated.

The impedance of the impedance improvement device 12 itself is +
A value of about j2Ω to +120Ω is preferable. If the impedance is too small, it can accommodate a large capacity equipment capacitor, but if there is no equipment capacitor and only the impedance improvement device is connected to the power line, the signal voltage will drop. On the other hand, if the impedance is too large, the effect of connecting an impedance improvement device will be small because it can only be used with equipment capacitors of small capacity. In order to lower the resonance Q and stabilize the characteristics, a resistor may be connected in parallel with the coil 13, or the coil 13. A resistor may be connected in series with the capacitor 14.

In this impedance improvement device, the load current of the electrical equipment 3 does not flow through the coil 13, so components for small signals can be used.
Becomes smaller. Also, the installation method is very easy, such as using the same outlet as the electrical device 3, for example. Taking advantage of its small size, it may be built into an electrical outlet.

Furthermore, since the impedance improvement device does not block signals, there is no place where communication is impossible.

Effects of the Invention According to the present invention, it is possible to provide an impedance improvement device that is small, easy to install, and does not block signals and prevent communication.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of a power line using a device according to an embodiment of the present invention, Fig. 2 is a wiring diagram of a power line explaining the principle of occurrence of a point where the signal voltage becomes zero, and Fig. 3 is a wiring diagram of a power line using a device according to an embodiment of the present invention. FIG. 4 is a diagram showing the connection of a conventional impedance improvement device to the power line, and FIG. 6 is a circuit diagram of the conventional impedance improvement device. 1...Transmitter, 2...Light line, 4...
...Equipment capacitor, 10. River... Inductance of power line, 12... Impedance improvement device.

Claims (1)

[Claims] An impedance improvement device in which a coil and a capacitor are connected in series, their constants are selected so that the composite impedance is inductive at the carrier frequency of power line communication, and both ends are connected to the power line in parallel with the capacitor of the electrical equipment. .