JP2004056197A - Power line communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power line communication system that prevents a communication signal of an electronic apparatus group for making communication via a power line from giving effect on the operation of an electronic apparatus group receiving supply of only power via the power line and surely transmits the communication signal to a transmission destination. <P>SOLUTION: In branch units 11, 12, 13 connected in series via a positive power line 3 and a GND power line 4, an electronic apparatus group receiving only supply of power from a battery 2 via the positive power line 3 and the GND power line 4 is connected to the branch units 11, 13. Then ECUs 16, 17, 18 making communication with each other via the positive power line 3 are connected to the branch unit 12, and a blocking filter 23 (24) for interrupting the communication signal transmitted from the ECUs 16, 17, 18 is interposed respectively between the branch units 11 and 12 (between the branch units 12 and 13). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power line communication system that performs communication using a power line as a transmission path.
[0002]
[Prior art]
In recent years, attention has been paid to so-called power line communication (PLC) in which communication is performed using a power line that supplies power as a transmission path, and is being introduced into various technical fields.
For example, in a control device disclosed in Japanese Patent Application Laid-Open No. 2001-144659, a plurality of electronic control units mounted on a vehicle communicate with each other via a power line connected to a battery of the vehicle, and cooperatively control the vehicle. Has been.
[0003]
[Problems to be solved by the invention]
However, since not only an electronic control unit that performs PLC but also an electronic device that receives only power supply from the battery, such as an audio device, is connected to the battery, when a power line is used as a communication transmission line, On the communication path of the electronic control unit that performs PLC, electronic devices that receive only power supply are mixed.
[0004]
For this reason, in the above control device, it is conceivable that the communication signal transmitted from the electronic control unit that performs the PLC flows as noise into the power supply of the electronic device that receives only the supply of power, and affects the operation.
The power supply of the electronic device often includes a bypass capacitor that bypasses noise superimposed on the DC power supplied from the power line to the ground of the battery. However, since the bypass capacitor also bypasses the communication signal together with the noise, the communication signal is attenuated in the middle of the communication path, and it is difficult to reliably transmit the communication signal to the destination. Is also conceivable.
[0005]
In order to solve the above-described problems, the present invention provides a communication signal of a group of electronic devices performing communication via a power line, which affects the operation of a group of electronic devices that receive only power supply via the power line. Further, it is an object of the present invention to provide a power line communication system capable of reliably transmitting a communication signal to a transmission destination.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the power line communication system according to claim 1, a continuous part of the power line is connected to a first connection area connecting a group of electronic devices that communicate with each other via the power line, and a power line. And a second connection region to which an electronic device group that receives only power supply is connected. Then, the communication signal of the electronic device group connected to the first connection area is interrupted by the signal interruption means provided between the first and second connection areas.
[0007]
According to such a power line communication system, a group of electronic devices that receive only power supply via a power line do not coexist on a communication path of a group of electronic devices that communicate with each other via a power line. Since the communication signal of the electronic device group performing communication is cut off in the first connection region, the communication signal of the electronic device group performing communication with each other via the power line receives only the supply of power via the power line. It is possible to prevent the operation of the electronic device group from being affected.
[0008]
It is most preferable that only the electronic device group that communicates with each other via the power line is connected to the first connection area. However, a part of the electronic device group that receives only the power supply via the power line is connected to the first connection region. It may be connected.
Here, when the power line is branched into a plurality of branch lines, the first connection region or the second connection region may be formed for each branch line.
[0009]
Further, the signal cut-off means resonates at the frequency of the communication signal and generates a larger impedance for the communication signal than for an electric signal having another frequency. May be blocked.
If the signal cutoff means is set in this manner, the first connection region becomes equivalent to a state separated from the second connection region at the frequency of the communication signal, so that the communication signal is transmitted on the communication path. Bypassing to the ground of the power line and attenuation can be suppressed. That is, the communication signal can be reliably transmitted to the destination.
[0010]
Also, the signal cutoff means may be constituted by a low-pass filter that allows only an electric signal having a frequency lower than the frequency of the communication signal to pass, for example. The same effect as that of the invention can be obtained.
The above-mentioned power line communication system may be mounted on a mobile body, for example.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is a configuration diagram of a power line communication system for a vehicle to which the present invention is applied.
As shown in FIG. 1, a power line communication system 1 includes a battery 2 that supplies power to each electronic device mounted on a vehicle, a positive terminal (+12 V) of the battery 2, and an electronic device mounted on each part of the vehicle. A power line 3 for electrically connecting the battery 2; a GND power line 4 for electrically connecting the ground (GND) side terminal of the battery 2 to the vehicle body 8; And a plurality of electronic devices connected to each of the positive power lines 3. Fuses 5, 6, and 7 are interposed between each of the positive power lines 3 branched into three branches and each of the electronic device groups 10, 20, and 30, and an overcurrent occurs. In this case, the fuses 5, 6, and 7 are disconnected to protect the electronic device groups 10, 20, and 30 from overcurrent.
[0012]
Here, the electronic device group 10 includes branch units 11, 12, and 13 formed of junction boxes and relay boxes for distributing power supplied from the battery 2. These branch portions 11, 12, and 13 are connected in series to each other via a positive power line 3 and a GND power line 4, and a plurality of electronic devices are connected to each of them.
[0013]
The branch portion 11 is connected to the fuse 5 and the vehicle body 8 via the positive power line 3 and the GND power line 4. The audio device 14 and the vehicle-mounted telephone 15 are connected to the branch unit 11 via the positive power line 3 and the GND power line 4, respectively, and are electrically connected to the battery 2 via the branch unit 11.
[0014]
The branch unit 12 is connected to the branch unit 11 via the positive power line 3 and the GND power line 4. Electronic control units (hereinafter, referred to as “ECUs”) 16, 17, and 18 are connected to the branch unit 12 via the positive power line 3 and the GND power line 4, respectively, and connected to the battery 2 via the branch unit 12. It is electrically connected.
[0015]
The branch unit 13 is connected to the branch unit 12 via the positive power line 3 and the GND power line 4. The vehicle speed sensor 19, the direction sensor 20, the GPS receiver 21, and the navigation device 22 are connected to the branch unit 13 via the positive power line 3 and the GND power line 4, respectively, and are electrically connected to the battery 2 via the branch unit 13. Connected.
[0016]
Here, the ECUs 16, 17, and 18 communicate with each other via the positive power line 3 and the branch unit 12, and communicate between the branch unit 12 and the branch unit 11, and between the branch unit 12 and the branch unit 13. Between them, blocking filters 23 and 24 for intercepting communication signals transmitted from the ECUs 16, 17 and 18 are inserted, respectively. The ECUs 16, 17, and 18, the branching unit 12, and the blocking filters 23 and 24 form an ECU network 50 that cooperatively controls the vehicle.
[0017]
Each of the electronic device groups 20 and 30 is different from the electronic device group 10 only in the type of electronic device provided therein, and has a configuration such as wiring of the positive power line 3 and the GND power line 4 between the electronic devices. Is substantially the same as the electronic device group 10. Therefore, the description is omitted here.
[0018]
Here, a circuit diagram of the blocking filters 23 and 24 is shown in FIG.
As shown in FIG. 2A, the blocking filters 23 and 24 are configured by connecting a coil L1 and a capacitor C1 connected in parallel with each other in series to the positive power line 3. Note that the coil L1 and the capacitor C1 connected in parallel to each other form a so-called parallel resonance circuit, and the frequency of a communication signal between the ECUs 16, 17, and 18 is smaller than that of an electric signal of another frequency. The inductance and the capacitance are set so that a large impedance is generated. The GND side power line 4 is connected to the vehicle body 8 near the coil L1 and the capacitor C1, and is set so as to take a so-called body ground near these elements.
[0019]
In the power line communication system 1 configured as described above, the audio device 14, the vehicle telephone 15, the vehicle speed sensor 19, the azimuth sensor 20, which receives only power supply from the battery 2 via the positive power line 3 and the GND power line 4, The GPS receiver 21 and the navigation device 22 are not mixed between the ECUs 16, 17 and 18, and the communication signals of the ECUs 16, 17 and 18 are cut off in the ECU network 50 by the blocking filters 23 and 24. 3 and the communication signals of the ECUs 16, 17, 18 communicating with each other via the GND side power line 4 affect the operation of other electronic devices that receive only power supply via the positive side power line 3 and the GND side power line 4. Can be prevented.
[0020]
The impedance of the blocking filters 21 and 22 resonates with the frequency of the communication signals of the ECUs 16, 17 and 18, and increases, so that the ECU network 50 is disconnected from the branch units 11 and 13 at the frequency of the communication signals. Therefore, even if the power supply of another electronic device is provided with a bypass capacitor, the communication signal can be suppressed from being bypassed to the GND power line 4 on the communication path and attenuated. That is, the communication signal can be reliably transmitted to the destination.
[0021]
Therefore, according to the power line communication system 1, it is possible to prevent the communication signal of the electronic device group performing communication via the power line from affecting the operation of the electronic device group which receives only power supply via the power line, and Thus, it is possible to provide a power line communication system capable of reliably transmitting a communication signal to a transmission destination.
[0022]
Here, in the power line communication system 1, any of the blocking filters shown in FIGS. 2B to 2H may be used instead of the blocking filters 23 and 24.
First, the blocking filter 40 shown in FIG. 2B has an inductance set so as to generate a larger impedance for an electric signal having a frequency higher than the frequency of the communication signal than for an electric signal having a frequency lower than the frequency of the communication signal. The connected coil L2 is connected in series to the positive power line 3 to constitute a low-pass filter circuit that passes only electric signals having a frequency lower than the frequency of the communication signal.
[0023]
Next, in the blocking filter 41 shown in FIG. 2C, the coils L3, 4 connected in series to each other are connected in series to the positive power line 3, and a capacitor C1 is connected between the coils L3, 4 by the positive power line. 3 and a GND-side power line 4 to constitute a low-pass filter circuit. Note that the inductance of the coils L3 and L4 and the capacitance of the capacitor C2 are set such that the blocking filter 41 passes only electric signals lower than the frequency of the communication signal.
[0024]
The blocking filter 42 shown in FIG. 2D has a configuration in which the coils L5 and 6 connected in series are connected in series to the positive power line 3 and the coil L7 and the capacitor C3 connected in series are connected to the coil L7. The side is connected to the connection point of the coils L5 and L6, and the side of the capacitor C3 is connected to the GND side power line 4, thereby forming a low-pass filter circuit. Note that the inductances of the coils L5, L6, and L7 and the capacitance of the capacitor C3 are set so that the blocking filter 42 passes only electric signals lower than the frequency of the communication signal.
[0025]
The blocking filter 43 shown in FIG. 2E is composed of a capacitor C4 inserted between the positive power line 3 and the GND power line 4. However, the capacitance of the capacitor C4 is set so that the capacitor C4 and the stray inductance of the positive power line 3 equivalently constitute a low-pass filter.
[0026]
The blocking filter 44 shown in FIG. 2F has a low-pass filter in which a coil 8 is connected in series to the positive power line 3 and a capacitor C5 is inserted between one end of the coil L8 and the GND power line 4. Is composed. In the blocking filter 44, it is desirable to connect the coil L8 side to the ECU network 50.
[0027]
The blocking filter 45 shown in FIG. 2G is composed of ferrite beads 46 attached to the positive power line 3. The magnetic force of the ferrite beads 46 is set such that the positive power line 3 generates a large impedance for an electric signal having a frequency equal to or higher than the frequency of the communication signal, and constitutes a so-called low-pass filter.
[0028]
The blocking filter 47 shown in FIG. 2H includes ferrite beads 48 and 49 attached to the positive power line 3 and the GND power line 4, respectively. As in the case of the blocking filter 45, the magnetic force of the ferrite beads 48, 49 is set so that the positive power line 3 and the GND power line 4 generate a large impedance with respect to an electric signal having a frequency equal to or higher than the frequency of the communication signal. This constitutes a so-called low-pass filter.
[0029]
In the blocking filters 40, 41, 42, 43, 44 and 45, the GND-side power line 4 is connected to the vehicle body 8 in the vicinity of the elements constituting the blocking filters 40, 41, 42, 43, 44 and 45. I have. Thereby, in particular, in the blocking filters 41, 42, 43, and 44, the element connected between the positive power line 3 and the GND power line 4 is equivalent to being linearly connected to the vehicle body 8. The wiring length of the GND-side power line 4 from the connection point between the element and the GND-side power line 4 to the vehicle body 8 is increased, and it is possible to prevent the frequency characteristics of the blocking filter from changing from desired characteristics.
[0030]
As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and it goes without saying that various forms can be adopted as long as they belong to the technical scope of the present invention. .
For example, in the above embodiment, both the positive power line 3 and the GND power line 4 are wired inside the vehicle, but the GND power line 4 may be omitted. In this case, as shown in FIG. 3, if there is a terminal to be grounded, the blocking filter may be directly connected to the vehicle body 8.
[0031]
In the above embodiment, the GND power line 4 is connected to the vehicle body 8 by each of the blocking filters. However, the connection of the GND power line 4 to the vehicle body 8 by each of the blocking filters may be omitted. good. In this case, as shown in FIG. 4, the same element as that inserted in the positive power line 3 is connected in series to the GND power line 4 wired near the element inserted in series with the positive power line 3. Just insert it into In the case of the blocking filter 43, a power line having the same stray inductance as the positive power line 3 may be wired as the GND power line.
[0032]
In the above embodiment, each of the electronic device groups 10, 20, and 30 communicates with the electronic device that receives only power supply via the positive power line 3 and the GND power line 4, via the positive power line 3. And an electronic device group including only electronic devices that receive only power supply via the positive power line 3 and the GND power line 4 and communicate with each other via the positive power line 3. It is also possible to constitute a group of electronic devices constituted only by the ECUs to be performed, and to connect them separately to each of the positive power lines 3 branched into three branch lines. In this case, the blocking filter is provided in a region from a portion where the positive power line 3 branches into three branch lines to a fuse to which a group of electronic devices performing PLC is connected, or a group of electronic devices performing PLC from the fuse. It suffices if one is provided in the region leading up to it.
[0033]
In the above embodiment, the electronic devices connected to the ECU network 50 are only the ECUs 16, 17, and 18 that communicate with each other via the positive power line 3. However, the electronic devices are connected via the positive power line 3 and the GND power line 4. An electronic device that receives only power supply may be included.
[0034]
Further, in the above embodiment, the PLC is performed via the power line through which the DC power is transmitted. However, the PLC may be performed via the power line through which the AC power is transmitted.
In the above embodiment, the present invention is applied to a vehicle, but may be applied to other moving objects such as an aircraft and a ship.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicle power line communication system to which the present invention is applied.
FIG. 2 is a circuit diagram of a blocking filter applicable to the power line communication system 1.
FIG. 3 is a circuit diagram showing a configuration of a blocking filter to be applied when the GND power line 4 is omitted.
FIG. 4 is a circuit diagram showing a configuration of a blocking filter to be applied when connection of a GND side power line 4 to a vehicle body 8 is omitted in each of the blocking filters.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Power line communication system, 2 ... Battery, 3 ... Positive side power line, 4 ... GND side power line, 5, 6, 7 ... Fuse, 8 ... Car body, 10, 20, 30 ... Electronic device group, 11, 12, 13 ... Branch unit, 14 audio device, 15 on-vehicle telephone, 16, 17, 18 ECU, 19 vehicle speed sensor, 20 direction sensor, 21 GPS receiver, 22 navigation device, 23, 24, 40, 41, 42, 43, 44, 45, 47: blocking filter; 46, 48, 49: ferrite beads; 50: ECU network.

Claims (5)

A power line communication system that performs communication using a power line that supplies power as a transmission path,
A continuous part in the power line,
A first connection region connecting a group of electronic devices that communicate with each other via the power line;
Dividing the electronic device group that receives only the supply of power through the power line into a second connection region,
A power line communication system, comprising: a signal cutoff unit that cuts off a communication signal of the electronic device group connected to the first connection region between the first and second connection regions. The power communication system according to claim 1, wherein the power line branches into a plurality of branch lines, and the first connection region or the second connection region is formed for each branch line. The signal blocking unit resonates with a frequency of the communication signal, and blocks the communication signal by generating a larger impedance for the communication signal than for an electrical signal having another frequency. The power line communication system according to claim 1 or 2. The power line communication system according to claim 1, wherein the signal blocking unit includes a low-pass filter that allows only an electric signal having a frequency lower than a frequency of the communication signal to pass. The power line communication system according to any one of claims 1 to 4, wherein the power line communication system is mounted on a mobile body.

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