JP2008172372A - Common mode current detector, and power-line communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common mode current detector and a power-line communication device, the common mode current detector being enabled to detect an actually generated common mode current to decide its level. <P>SOLUTION: The common mode current detector includes an antenna unit 2 which receives an electromagnetic wave radiated from a power line L or an AC cable 10 connected to the power line L, a detecting circuit unit 3 which is connected to the antenna unit 2 to detect the common mode current generated at the antenna unit 2, and an abnormality decision unit 4 which decides whether or not a detected amount of the common mode current by the detecting circuit unit 3 is larger than a predetermined value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a common mode current detector suitable for radio wave leakage detection in power line communication and a power line communication apparatus including the common mode current detector.

  In recent years, power line communication (PLC: Power Line Communication) that performs data communication between communication devices via a power line wired in a building such as a general house has been studied. In this power line communication, there is a problem of a leakage electromagnetic field in which radio waves leak indoors from the power line during communication, and it is known that a leakage electromagnetic field is generated particularly when a common mode current is generated in the line.

Further, regarding radio wave leakage in power line communication, there is a concept of LCL (vertical voltage conversion loss). The LCL is a parameter representing the balance of the line and is an extremely important characteristic that directly affects the level of the interference wave radiated from the line. Specifically, as LCL becomes smaller, radio wave leakage tends to increase. In general Japanese houses, LCL is about 30 dB on average, and in the worst environment, LCL is expected to be about 16 dB at 99%. ing.
For this reason, conventionally, various techniques for suppressing such radio wave leakage have been proposed.

  For example, Patent Document 1 proposes a power line communication modem in which a common mode filter is provided between a modem body and an input / output terminal. In this technology, a common mode filter is provided in a modem to suppress common mode noise caused by a common mode current generated in a power line or a cable.

JP 2004-266634 A

  In power line communication, the LCL differs depending on the wiring state of the power line and the state of the connected electrical equipment, etc., and the common mode current fluctuates depending on the wiring environment of the power line, etc. There is an inconvenience that causes interference. In the technique of Patent Literature 1, the power line communication device is provided with a common mode current suppression unit. However, since it is a uniform suppression unit, the actual common mode current that fluctuates as described above, particularly a level that can be suppressed. It was difficult to take appropriate measures to cope with the common mode current increased beyond the above.

  The present invention has been made in view of the above-described problems, and provides a common mode current detector capable of detecting the actually generated common mode current and determining the level thereof, and a power line communication apparatus including the common mode current detector. The purpose is to provide.

  The present invention employs the following configuration in order to solve the above problems. That is, the common mode current detector of the present invention includes a receiving unit that receives an in-phase signal or a radiated electromagnetic wave from a power line or an AC cable connected to the power line, and a common mode that is connected to the receiving unit and is generated in the receiving unit. A detection circuit unit for detecting a current and an abnormality determination unit for determining whether or not the detection amount of the common mode current by the detection circuit unit is equal to or greater than a predetermined value.

  In this common mode current detector, the receiving unit receives the in-phase signal or radiated electromagnetic wave from the power line or the AC cable, and the common mode current generated at that time is detected by the detection circuit unit and detected by the abnormality determination unit. It is determined whether or not the detected amount of the common mode current is equal to or greater than a predetermined value. That is, if the receiving unit is placed close to the power line or AC cable to be measured to receive the radiated electromagnetic wave or is connected to receive the in-phase signal, the common mode current generated in the wiring of the power line communication device connected thereto is It can be determined whether or not the value exceeds a predetermined value. As a result, it is possible to appropriately take measures such as stopping power line communication by the power line communication device at a location where a common mode current of a predetermined value or more is generated.

  In the common mode current detector of the present invention, the abnormality determination unit includes an abnormality warning unit that displays a warning or generates a warning sound when the detected amount is a predetermined value or more. That is, in this common mode current detector, the abnormality warning unit generates a warning display or a warning sound when the detected amount of the common mode current is greater than or equal to a predetermined value. When it increases above, it can be easily recognized.

  In the common mode current detector of the present invention, the receiving unit is an antenna unit that is exposed to the outside. That is, in this common mode current detector, since the receiving unit is an antenna unit that is installed to be exposed to the outside, by installing the antenna unit in an arbitrary external space, the radiated electromagnetic wave at the installation location is received, and A common mode current generated at the installation position can be detected.

  In the common mode current detector of the present invention, the receiving unit is an antenna line provided along a solid line of the AC cable. That is, in this common mode current detector, since the receiving unit is an antenna line provided along the solid line of the AC cable, the electromagnetic wave radiated from the solid line of the AC cable is received by the antenna line. The resulting common mode current can be detected more accurately.

  In the common mode current detector of the present invention, the receiving unit is a coupling circuit unit that is connected to the AC cable and receives an in-phase signal in the AC cable. That is, in this common mode current detector, since the receiving unit is a coupling circuit unit that receives the in-phase signal in the AC cable, it is more accurate by directly drawing the common-mode signal from the AC cable by the coupling circuit unit. In addition, the common mode current can be detected with high accuracy.

  The power line communication device of the present invention includes a power line communication unit that is connected to a power line and performs data communication via the power line, and the common mode current detector of the present invention, wherein the power line communication unit is operated by the abnormality determination unit. Data communication is stopped when it is determined that the detected amount is equal to or greater than a predetermined value. That is, in this power line communication device, when the power line communication unit determines that the detected amount of the common mode current is equal to or greater than the predetermined value by the abnormality determination unit, the radio wave emission caused by the power line communication is stopped. Properly prevent radio wave interference.

  In the power line communication device of the present invention, a coupler connected to the power line via the AC cable, a switching power supply connected to the power line via the AC cable and supplying power to the power line communication unit, and the coupling An electromagnetic wave shielding case for accommodating a device is provided, and at least the receiving part of the common mode current detector is accommodated in the electromagnetic wave shielding case together with the coupler. In other words, in this power line communication device, the receiving part of the common mode current detector is also housed in the electromagnetic shielding case together with the coupler, so that it is arranged in the same case as the coupler that easily detects the common mode current. It becomes easy to detect the mode current. In addition, since the receiving unit is spatially independent from the outside by the electromagnetic shielding case, it is possible to improve the detection accuracy by blocking the interference wave from the outside.

  According to the common mode current detector of the present invention, the receiving unit receives the in-phase signal or the radiated electromagnetic wave from the power line or the AC cable, the common mode current is detected by the detection circuit unit, and the detection amount is detected by the abnormality determination unit. Therefore, it is possible to easily detect the common mode current from the power line or the AC cable and determine whether or not it is an abnormal level. That is, it is possible to easily grasp the common mode current that fluctuates according to the wiring environment of the power line, and it is possible to take appropriate measures when the abnormality increases. Therefore, in the power line communication device equipped with the common mode current detector of the present invention, when the detected amount of the common mode current increases to a predetermined value or more, the radio wave emission is automatically stopped by stopping the power line communication. Radio wave interference can be prevented.

  Hereinafter, a first embodiment of a common mode current detector according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the common mode current detector 1 of the present embodiment includes an antenna unit (reception unit) 2 that receives radiated electromagnetic waves from the power line L, and a common mode that is connected to the antenna unit 2 and is generated in the antenna unit 2. A detection circuit unit 3 that detects a current and an abnormality determination unit 4 that is a circuit that determines whether or not the detection amount of the common mode current by the detection circuit unit 3 is equal to or greater than a predetermined value.

  The detection circuit unit 3 includes a filter 5 that is connected to the antenna unit 2 and limits the frequency band to 2 to 30 MHz, for example, and an amplifier unit 6 that is connected to the filter 5 and amplifies the common mode current input through the filter 5. And a linear detector 7 connected to the amplifier unit 6 and a detection-side capacitor 8 connected between the linear detector 7 and the ground G. In the filter 5, the frequency is limited to 2 to 30 MHz in order to prevent picking up other noise.

  The abnormality determination unit 4 is connected to a linear detector 7 and is provided with an abnormality warning unit 9 that displays a warning and generates a warning sound when the detected amount is a predetermined value or more. For example, when the detected amount exceeds a predetermined value, the abnormality warning unit 9 generates a warning sound from a built-in speaker and lights a warning lamp such as an LED to display a warning.

  The antenna unit 2 is installed in the vicinity of the AC cable 10 of the power line communication device that protrudes outside and is connected to the power line L. In particular, in the power line communication device, it is preferable to dispose the antenna unit 2 near the coupler 11 connected to the power line L via the AC cable 10. The coupler 11 includes a pair of coupler wires 12 connected to the AC cable 10, a pair of coupler capacitors 13 connected to the pair of coupler wires 12, and one end side connected to the coupler capacitor 13. And the other end side is constituted by a transformer 15 connected to a communication unit signal line 14 to a power line communication unit (not shown) of the power line communication device.

  In the common mode current detector 1 of the present embodiment, the antenna unit 2 receives the radiated electromagnetic wave from the power line L, the common mode current generated at that time is detected by the detection circuit unit 3, and the abnormality determination unit 4 It is determined whether or not the detected amount of the detected common mode current is equal to or greater than a predetermined value. That is, if the antenna unit 2 is installed close to the power line L to be measured, it can be determined whether or not the common mode current generated in the wiring of the power line communication device connected to the antenna unit 2 is equal to or greater than a predetermined value. As a result, it is possible to appropriately take measures such as stopping power line communication by the power line communication device at a location where a common mode current of a predetermined value or more is generated.

In particular, since the antenna unit 2 is exposed to the outside, by installing the antenna unit 2 in an arbitrary external space, radiated electromagnetic waves at the installation location are received and the common mode current generated at the installation location is detected. can do.
Further, since the abnormality warning unit 9 performs a warning display and a warning sound when the detected amount of the common mode current is equal to or greater than a predetermined value, when the common mode current increases to a predetermined value or more due to a change in the wiring environment or the like. Can be easily recognized.

  Next, a second embodiment of a common mode current detector and a power line communication device according to the present invention will be described with reference to FIGS. In the following embodiments, the same constituent elements described in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIGS. 2 and 3, the power line communication device of the second embodiment includes a coupler 11 connected to the power line L via the AC cable 10, and a power line connected to the AC cable 10 via the coupler 11. Common mode current detection for detecting a common mode current by receiving an electromagnetic wave radiated from a power line communication unit 22 that performs data communication using L, an application device 23 such as an audio device connected to the power line communication unit 22, and an AC cable 10. A power source L, a switching power supply 24 connected to the power line L via the AC cable 10 and supplying power to the power line communication unit 22, the application device 23, and the common mode current detector 21, and the coupler 11 and the common mode current detector 21. And an electromagnetic wave shielding case 25 for housing the battery.

The power line communication unit 22 divides data such as audio data into a plurality of subcarriers, for example, and transmits and receives data via a power line L at a carrier frequency corresponding to the plurality of subcarriers (not shown) and data reception Part (not shown).
The switching power supply 24 converts an AC voltage from the power line L into a DC voltage, controls an output voltage based on the switching frequency, and supplies power to the power line communication unit 22, the application device 23, and the common mode current detector 21. is there.

  The coupler 11 includes a pair of coupler wires 12 connected to the AC cable 10, a coupler capacitor 13 connected to the pair of coupler wires 12, respectively, as in the first embodiment described above. One end is connected to the coupler capacitor 13 and the other end is composed of a transformer 15 connected to the communication part signal line 14 to the power line communication part 22.

  The common mode current detector 21 includes the detection circuit unit 3 and the abnormality determination unit 4 similar to those of the first embodiment described above, but the antenna unit 2 is configured as shown in FIGS. The difference is that the antenna line is embedded in the AC cable 10 and provided along the AC line (solid line) 10 a of the AC cable 10.

The abnormality determination unit 4 is connected to the power line communication unit 22 and is set to transmit a signal to the power line communication unit 22 when the detected amount is determined to be equal to or greater than a predetermined value.
The power line communication unit 22 is set to stop the data communication by receiving the signal from the abnormality determination unit 4 when the abnormality determination unit 4 determines that the detected amount is equal to or greater than a predetermined value.
The AC cable 10 is connected to the power line L by being connected to the outlet plug 26 at the front end and inserted into the outlet jack 27 of the power line L.

  As shown in FIG. 3, the outlet plug 26 includes a pair of plug terminals 26 a that can be inserted into a pair of outlet jacks 27 of the power line L, and a pair of AC lines of the AC cable 10 with one end connected to the pair of plug terminals 26 a. A common mode choke coil 27 composed of a pair of plug signal lines 26b whose other end is connected to 10a, a magnetic core 26c in which the pair of plug signal lines 26b is wound in a cancel winding, and the common mode choke coil 27 sandwiched therebetween And a pair of in-plug capacitors 26d connected in parallel to the pair of plug signal lines 26b, and a sealing resin 28 that covers the plug signal line 26b and the magnetic core 26c and is housed inside. That is, the in-plug capacitor 26d is stretched over and connected to the pair of plug signal lines 26b so as to sandwich the common mode choke coil 27.

The electromagnetic wave shielding case 25 is formed by forming a metal thin film on the surface or inner surface of, for example, a metal case or a resin case main body, and has a function of absorbing, attenuating, reflecting, and blocking electromagnetic waves.
Although the switching power supply 24, the coupler 11, and the common mode current detector 21 are provided on the same substrate (not shown), only the coupler 11 and the common mode current detector 21 are covered with the electromagnetic shielding case 25. It is stored. Note that the switching power supply 24, the coupler 11, and the common mode current detector 21 may be provided on separate substrates, and the substrates on which the coupler 11 and the common mode current detector 21 are mounted may be housed in the electromagnetic shielding case 25. Absent.

  The coupler 11 and the power line communication unit 22 are connected by the communication unit signal line 14 as described above. The communication unit signal line 14 and the AC line 10a of the AC cable 10 are composed of twisted pairs. As shown in FIG. 4, the AC cable 10 includes the AC wire 10a, an insulating inner covering material 10b that covers the AC wire 10a, and an electromagnetic wave shielding material 10c such as a mesh copper wire that covers the inner covering material 10b. And an insulating outer covering material 10d covering the electromagnetic wave shielding material 10c. The antenna unit 2 is disposed inside the electromagnetic wave shielding material 10c.

In the common mode current detector 21 of the second embodiment, since the antenna unit 2 is an antenna line provided along the AC line 10a of the AC cable 10, electromagnetic waves radiated from the AC line 10a of the AC cable 10 are approached. The common mode current caused by the AC cable 10 can be detected more accurately by receiving with the antenna unit 2 that has been performed.
In the power line communication device of the second embodiment, the power line communication unit 22 stops data communication when the abnormality determination unit 4 determines that the detected amount of the common mode current is equal to or greater than a predetermined value. The generated radio wave radiation is stopped, and radio wave interference can be appropriately prevented.

  Since the coupler 11 is housed in the electromagnetic wave shielding case 25, noise from the switching power supply 24 is absorbed, cut off, and reflected by the electromagnetic wave shielding case 25, and the noise is superimposed on the wiring of the coupler 11 to cause the common mode current. Can be prevented, and the size including the switching power supply 24 as a whole can be reduced as compared with the case where it is housed in a shield case, and grounding is facilitated. Therefore, the communication characteristics are improved, the communication distance and the communication reliability are improved, and the entire device can be downsized and manufactured at low cost.

  In addition, since the communication unit signal line 14 and the AC cable 10 that connect the coupler 11 and the power line communication unit 22 are configured by the twisted pair AC line 10a, in the case of a normal paired line, radiation from a certain direction is performed. A differential distance between the paired wires is likely to occur with respect to the noise, and a differential noise is likely to occur. On the other hand, the differential AC line 10a with no paired distance is less likely to generate the differential noise, and the influence of the noise is reduced. Further reduction can be achieved.

  The electromagnetic wave shielding case 25 and the electromagnetic wave shielding material 10c are not only radiated noise from the switching power supply 24, but also when a power source such as a personal computer or a television set around the power line communication device or an AC cable is in close proximity. It also has a noise reduction effect for noise radiated from.

  Next, a third embodiment of the common mode current detector and the power line communication device according to the present invention will be described with reference to FIG.

  The difference between the third embodiment and the second embodiment is that, in the second embodiment, the antenna unit 2 as a receiving unit is arranged along the AC line 10a of the AC cable 10, whereas the third embodiment is different from the third embodiment. In the common mode current detector 31 and the power line communication apparatus including the same, as shown in FIG. 5, a coupling circuit unit (receiving unit) 32 that is connected to the AC cable 10 and receives an in-phase signal in the AC cable 10. Is provided in place of the antenna unit 2.

  The coupling circuit unit 32 includes a pair of coupling lines 32a having one end connected to the pair of AC lines 10a of the AC cable 10, and a pair of coupling circuit capacitors 32b having one end connected to each coupling line 32a. The filter 5 is connected to a connecting line 32c that connects the other ends of the coupling circuit capacitors 32b. The coupling circuit unit 32 is housed in the electromagnetic wave shielding case 25 together with the coupler 11 and the detection circuit unit 3.

In the common mode current detector 31 of the third embodiment, since the coupling circuit unit 32 is connected to the AC cable 10 to directly receive the in-phase signal, the coupling circuit unit 32 directly receives the in-phase signal from the AC cable 10. By pulling in, the common mode current can be detected more accurately and with high accuracy.
Further, since the coupling circuit unit 32 is also housed in the electromagnetic wave shielding case 25 together with the coupler 11 and the detection circuit unit 3, the coupling mode unit 32 is arranged in the same case as the coupler 11 in which the common mode current is easily detected. Can be easily detected. In addition, since the coupling circuit unit 32 is spatially independent from the outside by the electromagnetic wave shielding case 25, it is possible to improve the detection accuracy by blocking the interference wave from the outside.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

1 is an overall configuration diagram including a circuit configuration showing a common mode current detector of a first embodiment according to the present invention. It is a whole lineblock diagram showing a power line communication device in a common mode current detector and power line communication device of a 2nd embodiment concerning the present invention. In 2nd Embodiment, it is a block diagram which shows an AC cable and a common mode current detector. In 2nd Embodiment, it is sectional drawing which shows an AC cable. It is a block diagram including the circuit structure which shows the coupler and common mode current detector of a power line communication apparatus in the common mode current detector and power line communication apparatus of 3rd Embodiment which concern on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 21, 31 ... Common mode current detector, 2 ... Antenna part (receiving part), 3 ... Detection circuit part, 4 ... Abnormality determination part, 9 ... Abnormal warning part, 10 ... AC cable, 10a ... AC line (AC Solid line of cable), 11 ... coupler, 22 ... power line communication unit, 24 ... switching power supply, 25 ... electromagnetic wave shielding case, 32 ... coupling circuit unit (receiving unit), L ... power line

Claims (7)

A receiving unit for receiving an in-phase signal or a radiated electromagnetic wave from a power line or an AC cable connected to the power line;
A detection circuit unit connected to the reception unit for detecting a common mode current generated in the reception unit;
A common mode current detector, comprising: an abnormality determination unit that determines whether or not a detection amount of the common mode current by the detection circuit unit is equal to or greater than a predetermined value. The common mode current detector according to claim 1,
The common mode current detector, wherein the abnormality determination unit includes an abnormality warning unit that displays a warning or generates a warning sound when the detected amount is a predetermined value or more. In the common mode current detector according to claim 1 or 2,
The common mode current detector, wherein the receiving unit is an antenna unit that is exposed to the outside. In the common mode current detector according to claim 1 or 2,
The common mode current detector, wherein the receiving unit is an antenna line provided along a solid line of the AC cable. In the common mode current detector according to claim 1 or 2,
The common mode current detector, wherein the receiving unit is a coupling circuit unit that is connected to the AC cable and receives an in-phase signal in the AC cable. A power line communication unit connected to the power line and performing data communication via the power line;
A common mode current detector according to any one of claims 1 to 5,
The power line communication device stops data communication when the abnormality determination unit determines that the detected amount is equal to or greater than a predetermined value. The power line communication apparatus according to claim 6,
A coupler connected to a power line via the AC cable;
A switching power supply connected to a power line via the AC cable and supplying power to the power line communication unit;
An electromagnetic shielding case for housing the coupler;
The power line communication apparatus, wherein at least the receiving unit of the common mode current detector is housed in the electromagnetic wave shielding case together with the coupler.

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