JP2006253797A - Power line carrier communication circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress occurrence of a common mode current and a radiated radio wave in a power line carrier communication circuit. <P>SOLUTION: The power line carrier communication circuit 1 includes a balancing circuit in which when a signal voltage is applied to one of voltage lines and a neutral line, a signal voltage having polarity opposite to that of the applied signal voltage occurs in the other voltage line and the neutral line in a single-phase three-line cable with a set of three lines of the first voltage line 4, the second voltage line 5, and the neutral line 7 connected to a grounding line 6. If the power line carrier communication circuit 1 is used, a voltage V<SB>O</SB>to ground of the neutral line 7 becomes nearly zero. Consequently, the occurrence of the common mode current and the radiated radio wave can be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power line carrier communication circuit.

  In recent years, broadband Internet connection services using DSL and CATV networks have become very popular. Power line carrier communication uses a power line installed to supply power to the equipment as a transmission line, so it is not necessary to install a new communication line for communication. It is attracting attention as.

  For example, as shown in FIG. 3, the power line carrier communication circuit 101 is a circuit in which a modem 104 is connected from a transformer 102 to a power line 103 laid in a house. In the illustrated example, the power line 103 is a single-phase three-wire electric wire in which three lines of the first voltage line 105, the second voltage line 106, and the neutral line 108 connected to the ground line 107 are set. The modem 104 is connected to the second voltage line 106 and the neutral line 108.

  In such a configuration, the power line 103 is protected and grounded by the ground line 107 and is an unbalanced circuit including the ground due to the action of the ground capacitance 109. Since the transmission circuit is unbalanced, the common mode current 110 is likely to be generated, and when a high frequency signal is transmitted by power line carrier communication, a radiated radio wave is generated. In such power line carrier communication, the low voltage line attached to a high position between the power poles works in the same way as a grounded antenna. There is a case.

As a means to suppress the common mode current, a blocking impedance that is effective only for the common mode current is inserted into the connection part of the power line and the modem and the power line itself, or a blocking impedance that is effective only in the high frequency band is inserted into the ground line of the power line There is a method of insertion (Patent Document 1).
JP 2004-336456 A

  The means to suppress the common mode current using the blocking impedance depends on the parasitic capacitance generated between the iron core and winding of the coil that constitutes the blocking impedance and the parasitic capacitance generated between the coil windings. It is difficult to sufficiently increase the impedance value in the high frequency band, a sufficient effect for suppressing the common mode current cannot be obtained, and the unbalance of the transmission circuit is not improved.

  The power line carrier communication circuit according to the present invention includes a first voltage line, a second voltage line, and a voltage of one of the three-phase power lines that are a set of three neutral lines connected to the ground line. In a power line carrier communication circuit that performs communication via a line and a neutral line, if a signal voltage is applied to one voltage line and neutral line of a single-phase three line, the polarity is opposite to the other voltage line and neutral line A balanced circuit for generating a signal voltage is provided.

  According to this power line carrier communication circuit, a balanced circuit is provided in which when a signal voltage is applied to one voltage line and neutral line of a single-phase three-wire, a signal voltage of opposite polarity is generated on the other voltage line and neutral line. Therefore, when a signal voltage is applied to one of the voltage lines and the neutral line, a signal voltage having the opposite polarity is generated on the other voltage line and the neutral line. As a result, the signal current is canceled on the neutral line, Balanced transmission is performed via two voltage lines. As a result, the signal current is apparently transmitted through two voltage lines that are not grounded, and the generation of common mode current and the generation of radiated radio waves using the ground as a transmission circuit are suppressed.

  Hereinafter, an embodiment of a power line carrier communication circuit according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the power line carrier communication circuit 1 performs communication using a low-voltage power line 3 drawn into a house from a transformer 2 installed on a telephone pole or the like. The low-voltage power line 3 is composed of a single-phase, three-wire power line that includes a first voltage line 4, a second voltage line 5, and a neutral line 7 connected to the ground line 6. .

  The transformer 2 adjusts a household voltage from a high-voltage power line 8 through which a high-voltage current for power transmission flows, and supplies power to the low-voltage power line 3. The low-voltage power line 3 supplies electricity of 100 V to the house with a pair of the first voltage line 4 and the neutral line 7 and a pair of the second voltage line 5 and the neutral line 7.

  This power line carrier communication circuit 1 is provided with a balanced circuit in which, when a signal voltage is applied to one voltage line and neutral line of a single-phase three-wire, a signal voltage of opposite polarity is generated on the other voltage line and neutral line. Is.

  In this embodiment, as a balanced circuit, a first winding 11 connecting the first voltage line 4 and the neutral wire 7 and a second winding 12 connecting the second voltage line 5 and the neutral wire 7 are wound. The transformers 13 and 14 are attached to positions separated from the low-voltage power line 3, respectively. The transformers 13 and 14 have the first winding 11 and the second winding so that when a signal voltage is applied to one of the voltage lines and the neutral line, a signal voltage having the opposite polarity is generated on the other voltage line and the neutral line. The wire 12 is wound around the core material.

  Although not shown in the drawings, in this embodiment, the transformers 13 and 14 are each a toroidal member using a high-frequency magnetic material such as ferrite after the first winding 11 and the second winding 12 are wound together. Distributed cores are used. Thereby, it operates in a wide band. Capacitors 16 and 17 are attached to the first winding 11 and the second winding 12 to prevent a commercial frequency voltage from being directly applied and an overcurrent from flowing.

  Further, in this embodiment, one transformer 13 is attached to a facility ground that is secured and grounded, and a third winding 18 is added to the transformer 13 and an external modem 19 is attached. As a result, signals can be transmitted and received without breaking the balance of the single-phase three-wire both-side circuit.

  The modem 20 used in the power line carrier communication circuit 1 is connected to either the first voltage line 4 and the neutral line 7 or the second voltage line 5 and the neutral line 7 via a home outlet.

For example, as shown in FIG. 1, in the state in which the modem 20 to the second voltage line 5 and the neutral line 7 is connected, by the modem 20 during communication with the second voltage line 5 and the neutral line 7 signal voltages V ₁ Added. When the signal voltage V ₁ is applied to the second voltage line 5 and the neutral line 7, the second voltage line 5 and the neutral line 7 are connected to the first voltage line 4 and the neutral line 7 via the transformers 13 and 14. A signal voltage V ₂ having a polarity opposite to that of the signal voltage V ₁ applied to is generated.

As a result, in the neutral line 7, the signal current I ₁ resulting from the signal voltage V ₁ applied to the second voltage line 5 and the neutral line 7 and the signal voltage V ₂ applied to the first voltage line 4 and the neutral line 7 are detected. The signal currents I ₂ resulting from the above cancel each other, and apparently no current flows through the neutral wire 7. Further, since the first voltage line 4 and the second voltage line 5 are respectively coupled to the ground by the substantially equal ground capacitance 9, and can be regarded as a balanced circuit, the power line carrier communication circuit 1 has the first voltage line. 4 and the second voltage line 5 are in a state where the signal current is balanced and transmitted. Since balanced transmission of the signal current is performed in the first voltage line 4 and the second voltage line 5, the ground voltage V _O of the neutral line 7 serving as the voltage midpoint is substantially zero.

As described above, according to the power line carrier communication circuit 1, since the unbalance of the transmission circuit is improved and the ground voltage V _O of the neutral line 7 becomes substantially 0, the generation of the common mode current is suppressed, and the radiated radio wave is suppressed. Is also suppressed. Further, by using the two transformers 13 and 14, the transformer 13 removes the influence of the impedance imbalance caused by the transformer 2, and the transformer 14 removes the first voltage line 4 and the neutral line 7 or The effect of the unbalanced connection of the modem 20 to the two voltage lines 5 and the neutral line 7 can be eliminated, and the balanced transmission of the signal voltage can be realized over a wide range of the low-voltage power line 3, thereby enhancing the improvement effect. Moreover, the transformers 13 and 14 may be attached to the existing low-voltage power line in parallel connection. Compared with the series impedance insertion in which the electric wire is once cut and inserted, the common in power line carrier communication is relatively simple. Generation of mode current and generation of radiated radio waves can be suppressed.

  The power line carrier communication circuit according to one embodiment of the present invention has been described above, but the power line carrier communication circuit according to the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the case where there is an external modem on the telephone pole outside the house is exemplified, but there are a plurality of communication terminals in the house, and the modem 21 is installed in the house and these communication terminals are connected. However, as shown in FIG. 2, by similarly installing the transformers 13 and 14, the ground voltage of the neutral wire 7 becomes substantially zero, so the generation of common mode current is suppressed and the generation of radiated radio waves is suppressed. be able to.

  In addition, the balanced circuit is exemplified by the configuration in which the pair of transformers 13 and 14 are attached to the single-phase three-wire. However, the present invention is not limited to this. In addition, a circuit configuration in which a signal voltage having opposite polarities in the other voltage line and the neutral line can be widely adopted. Various modifications can also be made to the configuration of the transformer constituting the balanced circuit in the above embodiment.

Schematic which shows the power line carrier communication circuit which concerns on one Embodiment of this invention. Schematic which shows the power line carrier communication circuit which concerns on other embodiment of this invention. Schematic which shows a power line carrier communication circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power line carrier communication circuit 2 Transformer 3 Low voltage power line 4 First voltage line 5 Second voltage line 6 Ground line 7 Neutral line 11 First winding 12 Second winding 13, 14 Transformer 16, 17 Capacitor 18 Third volume Line 19 External modem 20 Modem

Claims (3)

The first voltage line, the second voltage line, and the neutral line connected to the grounding line are communicated via one voltage line and the neutral line among the single-phase three-wire power lines as a set. In the power line carrier communication circuit to perform,
A power line carrier characterized in that a balanced circuit is provided in which when a signal voltage is applied to one voltage line and neutral line of the single-phase three-wire, a signal voltage of opposite polarity is generated on the other voltage line and neutral line. Communication circuit.   The balanced circuit has a first winding connecting a first voltage line and a neutral wire and a second winding connecting a second voltage line and a neutral wire at a position apart from the single-phase three wires. The power line carrier communication circuit according to claim 1, further comprising a pair of transformers wound around the material.   3. The power line carrier communication circuit according to claim 2, wherein the transformer is one in which the first winding and the second winding are wound together and distributed in a toroidal core. 4.

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