JP2005236815A - Power line communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power line communication apparatus, capable of reducing influences of noise discharged from an electrical apparatus connected to a power line. <P>SOLUTION: The power line communication apparatus is provided with via a coupling circuit 2, which exchanges signals with an electric light line 101; a transmission circuit 7 for transmitting, to the electric light line 101, a signal-accommodating data via the coupling circuit 2; a reception filter circuit 3, which selectively passes signals within a predetermined frequency range among signals outputted from the coupling circuit 2; a receiving circuit 4 which acquires data from signals passed through the reception filter circuit 3; and a filter changeover switch SW1 for setting the predetermined frequency range, by switching selection of a first band-pass filter 31, a second band-pass filter 32, and a third band-pass filter 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power line communication apparatus that performs communication using a power line shared for power supply and communication.

  In recent years, networking has progressed in various technical fields due to advances in communication technology, and various devices in a building are being connected to the network. Such devices are networked by organically linking these devices, and by connecting the network outside the building and the network inside the building to operate these devices from an external communication terminal. By instructing it, it is intended to provide a safe and comfortable life while responding to energy saving and remote control. There are various communication signal transmission methods, but the advantage that there is no need to lay a new transmission line because the existing wiring is used, and the initial cost associated with the introduction is accordingly low, Because of the advantage that the aesthetics of the building is not impaired, power line communication using a power line (power line) for supplying power to these devices as a transmission path may be employed.

  In this power line communication, for example, a high frequency communication signal is superimposed on a commercial frequency power waveform, or the high frequency communication signal is separated from the power waveform and received. This is a communication method for transmitting and receiving through the network.

  FIG. 8 is a block diagram showing a configuration of a power line communication apparatus according to the background art. The power line communication apparatus 100 shown in FIG. 8 performs communication using a power line 101 that supplies commercial power AC 100 V, and includes a coupling circuit 102, a reception filter circuit 103, a reception circuit 104, a modem 105, a control circuit 106, and a transmission. A circuit 107 is provided.

  In such a power line communication apparatus 100, a signal superimposed on the commercial power supply AC100V is acquired from the power line 101 by the coupling circuit 102, the commercial AC frequency is cut, and a high frequency signal used for power line communication is generated. A desired power line communication signal that passes through the coupling circuit 102 and is output to the reception filter circuit 103 and is extracted by the reception filter circuit 103 is amplified and shaped by the reception circuit 104 and output to the modem 105, where it is amplified, etc. The signal is demodulated by the modem 105, and the demodulated data is received by the control circuit 106. The transmission data output from the control circuit 106 is modulated by the modem 105, amplified by the transmission circuit 107, and superimposed on the commercial power supply voltage AC100V in the power line 101 via the coupling circuit 102. (See, for example, Patent Document 1).

Then, as shown in FIG. 9, when a plurality of power line communication devices 100 are connected to the power line 101, data transmission / reception is performed between the plurality of power line communication devices 100 via the power line 101. For example, an inverter device such as an air conditioner and an electric device 109 such as an IH (Induction Heating) cooker are connected to the electric power line 101.
JP 2002-261661 A

  By the way, as a signal frequency used for the power line communication as described above, use of 10 kHz to 450 kHz is permitted by the Japanese radio law. On the other hand, the above-described inverter device and the electric device 109 such as an IH (Induction Heating) cooker emit noise having a frequency in the vicinity of several tens of kHz to the power line 101, and the noise level reaches several tens of volts. There is. For this reason, the signal frequency used for power line communication and the noise frequency emitted by the electric device 109 overlap, and the power line communication becomes difficult due to interference from noise emitted from the electric device 109. It was.

  Further, when a narrow band communication method such as an AM (Amplitude Modulation) modulation method is used as a modulation method used for power line communication, only the frequency used for communication by the coupling circuit 102 may be allowed to pass. However, in a modulation method using a wide band such as a spread spectrum method or a multicarrier method, the frequency characteristics of the coupling circuit 102 need to be wide, so that the influence of noise is ensured while ensuring the frequency band used for communication. It was difficult to reduce.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a power line communication apparatus that can reduce the influence of noise emitted from electrical equipment connected to the power line. .

  In order to achieve the above object, a power line communication device according to the present invention is a power line communication device that performs communication using a power line shared for power supply and communication, and a coupling unit that transmits and receives signals to and from the power line. A transmission unit that transmits a signal containing data to the power line via the coupling unit, a reception filter unit that selectively passes a signal in a predetermined frequency range from the signal output from the coupling unit, A receiving unit that acquires data from a signal that has passed through the receiving filter unit, and a setting unit that sets the predetermined frequency range are provided.

  In the power line communication device described above, the lower limit value in the predetermined frequency range is 10 kHz to 100 kHz.

  In the above power line communication apparatus, the reception filter unit includes a plurality of bandpass filters having different frequency bands and a switch for selecting any one of the plurality of bandpass filters, and the setting unit includes The switch is switched.

  In the power line communication apparatus described above, the plurality of bandpass filters are ladder LC filters, and the setting unit performs switching of orders in the ladder LC filter.

  In the above power line communication apparatus, the coupling unit includes a capacitor that cuts a power supply component in a signal acquired from the power line, the capacitor and a primary winding are connected in series, and a secondary winding is the reception filter unit. And a transformer connected to the transmission unit, and a capacitance switching unit that increases or decreases the capacitance of the capacitor, while the capacitance switching unit increases the capacitance of the capacitor when data is transmitted from the transmission unit, When the data is acquired by the receiving unit, the capacitance of the capacitor is reduced.

  Furthermore, in the above-described power line communication device, the coupling unit includes a capacitor that cuts a power supply component in a signal acquired from the power line, a transformer in which the capacitor and the primary winding are connected in series, and a secondary winding in the transformer. A winding number switching unit that increases or decreases the number of windings connected to the reception filter unit and the transmission unit, and the winding number switching unit, when data is acquired by the reception unit, While the number of windings is increased, the number of windings is decreased when a signal containing data is transmitted from the transmission unit.

In the power line communication apparatus, the coupling unit includes a capacitor that cuts a power supply component in a signal acquired from the power line, a primary winding connected in series with the capacitor, and a secondary winding connected to the reception filter. And a transformer connected to the transmitter and the transmitter,
Of the secondary windings in the transformer, the number of windings connected to the reception filter unit is larger than the number of windings connected to the transmission unit.

  The power line communication device having such a configuration selectively passes a signal in a predetermined frequency range that is set avoiding the frequency of noise emitted from the electrical equipment connected to the power line, and data is transmitted from the passed signal. Therefore, it is possible to reduce the influence of noise emitted from the electrical equipment connected to the power line.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of the power line communication apparatus according to the first embodiment of the present invention. A power line communication apparatus 1 shown in FIG. 1 performs communication using a power line 101 that supplies commercial power AC 100 V, and includes a coupling circuit 2, a reception filter circuit 3, a reception circuit 4, a modem 5, a control circuit 6, and a transmission circuit. 7, a frequency setting switch 8 and an order setting switch 9 are provided.

  The coupling circuit 2 includes, for example, a 0.22 μF capacitor C1 for cutting the commercial power supply frequency (power supply component), and a transformer T connected to the lamp line 101 via the capacitor C1, and a signal of 10 kHz to 450 kHz. Have been allowed to pass through. In the transformer T, the primary winding 21 is connected to the lamp line 101 via the capacitor C1, and the secondary winding 22 is connected to the reception filter circuit 3 and the transmission circuit 7.

  The reception filter circuit 3 includes a first band pass filter (BPF) 31, a second band pass filter (BPF) 32, a third band pass filter (BPF) 33, and a filter changeover switch SW1. The filter changeover switch SW1 switches the secondary winding 22 of the transformer T from any of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33 according to the control signal from the control circuit 6. Connect with

  The pass band of the first band pass filter 31 is, for example, 10 kHz to 450 kHz, the pass band of the second band pass filter 32 is, for example, 50 kHz to 450 kHz, and the pass band of the third band pass filter 33 is, for example, 100 kHz to 450 kHz. Yes. As described above, the first band-pass filter 31, the second band-pass filter 32, and the third band-pass filter 33 have different cutoff frequencies on the low frequency side and the same cutoff frequency on the high frequency side. Yes. That is, a plurality of band-pass filters having different cutoff frequencies are provided for a frequency in the vicinity of several tens of kHz that is a frequency of noise that is often emitted from the electric device 109. By selecting a band-pass filter, noise can be obtained. The cut-off frequency that can effectively cut the frequency is set. Then, a signal that has passed through any one of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33 is output to the reception circuit 4.

  FIG. 2 is a circuit diagram showing an example of the configuration of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33. The first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33 shown in FIG. 2 include filters F1, F2, and F3, and switches SW21, SW22, and SW23, respectively. The filter F1 and the filter F2 are connected via a two-pole switch SW21, and the filter F2 and the filter F3 are connected via a two-pole switch SW22. By the filters F1, F2, and F3, A ladder-type LC filter is configured.

  In the filter F1, a series circuit of an inductor L21 and a capacitor C21, a parallel circuit of an inductor L23 and a capacitor C23, and a series circuit of a capacitor C22 and an inductor L22 are connected in series. What is the capacitor C21 in the inductor L21? The opposite terminal and the terminal of the inductor L22 opposite to the capacitor C22 are connected to the filter changeover switch SW1, and both ends of the capacitor C23 are connected to the filter F2 via the switch SW21 and the pole P11 of the switch SW23. , P12 and connected to the receiving circuit 4 via the switch SW23.

  In the filter F2, a series circuit of a capacitor C24 and an inductor L24, a parallel circuit of an inductor L26 and a capacitor C26, and a series circuit of an inductor L25 and a capacitor C25 are connected in series, and both ends of the inductor L26 are connected to the switch SW21. Is connected to the filter F1. A terminal of the capacitor C24 opposite to the inductor L24 and a terminal of the capacitor C25 opposite to the inductor L25 are connected to the filter F3 via the switch SW22 and to the poles P21 and P22 of the switch SW23. Are connected to the receiving circuit 4 via the switch SW23.

  In the filter F3, a series circuit of an inductor L27 and a capacitor C27, a parallel circuit of an inductor L29 and a capacitor C29, and a series circuit of a capacitor C28 and an inductor L28 are connected in series. What is the capacitor C27 in the inductor L27? The terminal on the opposite side and the terminal on the opposite side to the capacitor C28 in the inductor L28 are connected to the filter F2 via the switch SW22. Both ends of the capacitor C29 are connected to the poles P31 and P32 of the switch SW23, and are connected to the receiving circuit 4 via the switch SW23.

  The constants of the inductors L21 to L29 and the capacitors C21 to C29 are set according to the passbands of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33, respectively.

  The switches SW21, SW22, and SW23 are switching switches for switching the filter order, and are switched according to the control signal output from the control circuit 6 based on the setting state of the order setting switch 9. As a result, the first band-pass filter 31, the second band-pass filter 32, and the third band-pass filter 33 are any of the second-order filter, the third-order filter, and the fourth-order filter according to the setting state of the order setting switch 9. Can be switched.

  The reception circuit 4 is composed of, for example, an amplifier circuit that amplifies the signal level output from the reception filter circuit 3 and a comparator that performs waveform shaping, and amplifies and shapes the signal output from the reception filter circuit 3. Output to the modem 5. The modem 5 is a modulation / demodulation circuit for the power line communication signal. The modem 5 demodulates the signal from the reception circuit 4 and outputs it to the control circuit 6, while modulating the signal from the control circuit 6 and outputs it to the transmission circuit 7.

  The control circuit 6 is a control circuit composed of a serial communication interface circuit such as a CPU (Central Processing Unit) or a USART (Universal Synchronous and Asynchronous Receiver-Transmitter), for example. Received data is acquired from the signal received from the power line communication device 1 via the power line 101, the coupling circuit 2, the reception filter circuit 3, the reception circuit 4, and the modem 5, and the unrepresented release is performed according to the received data. A control signal is output to an electric device such as an electric lamp to control its operation, or predetermined data is received from an electric device (not shown) connected to the control circuit 6, and the received data is sent to the modem 5 and the transmission circuit. 7, and transmitted to another power line communication device 1 via the coupling circuit 2 and the power line 101.

  In this case, the electrical device connected to the control circuit 6 is a device that operates using electricity as an energy source. For example, a device that adjusts an office environment or a dwelling environment such as a lighting fixture or an air conditioner, an elevator, an escalator, or the like. Mobility assistance equipment that assists the movement of people, measuring devices such as power meters, gas meters and water meters, smoke sensors, sensors such as temperature sensors, humidity sensors, and illuminance sensors, dwelling equipment such as electronic lock devices, televisions, Home appliances such as video tape recorders, DVD recorders and washing machines, information processing equipment such as computers, communication equipment such as telephones and facsimile machines, and medical equipment such as pulse meters, thermometers, blood oximeters and electrocardiographs, etc. It is.

  Further, the control circuit 6 switches the connection of the filter changeover switch SW <b> 1 according to the setting state of the frequency setting switch 8. The frequency setting switch 8 sets the passband frequency in the reception filter circuit 3 to any of, for example, 10 kHz to 450 kHz (cutoff frequency fc1), 50 kHz to 450 kHz (cutoff frequency fc2), and 100 kHz to 450 kHz (cutoff frequency fc3). This is a setting switch for accepting a frequency setting instruction from the user, and is composed of, for example, a dip switch.

  The control circuit 6 switches the connection of the switch SW2 according to the setting state of the order setting switch 9. The order setting switch 9 is a setting switch for receiving a filter order setting instruction from the user for switching the filter orders of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33. For example, it is composed of a dip switch or the like.

  In place of the frequency setting switch 8 and the order setting switch 9, for example, a communication interface such as infrared communication is provided, and the control circuit 6 receives a frequency setting instruction and a filter order setting instruction from the user via the communication interface. It is good also as a structure which receives.

  Next, the operation of the power line communication device 1 shown in FIG. 1 will be described. First, when the frequency setting switch 8 is set to a frequency of 10 kHz to 450 kHz, the filter changeover switch SW1 is switched according to the control signal from the control circuit 6, and the coupling circuit 2 and the first bandpass filter 31 are switched. Connected.

  Then, a signal superimposed on the commercial power supply AC100V is acquired from the power line 101 by the coupling circuit 2, and the commercial AC frequency is cut, and a signal having a frequency used for power line communication passes through the coupling circuit 2 and is received. It is output to the filter circuit 3. Then, a signal of 10 kHz to 450 kHz among the signals that have passed through the coupling circuit 2 passes through the first band pass filter 31 in the reception filter circuit 3, is amplified and shaped by the reception circuit 4, and is output to the modem 5. The signal is demodulated by the modem 5, and the demodulated data is received by the control circuit 6.

  On the other hand, transmission data output from the control circuit 6 is modulated by the modem 5, amplified by the transmission circuit 7, and superimposed on the commercial power supply AC 100 V in the power line 101 via the coupling circuit 2, thereby Data is transmitted to other power line communication devices via the network.

  Next, when communication by the power line communication device 1 is hindered by the influence of noise emitted from the electric device 109 connected to the power line 101, the user sets the frequency setting switch 8 to 50 kHz to 450 kHz, Or it can switch to the frequency setting of 100 kHz-450 kHz.

  FIG. 3 is a graph illustrating an example of frequency characteristics in the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33. In FIG. 3, the horizontal axis indicates the frequency f, and the vertical axis indicates the gain G of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33. The cutoff frequency fc1 of the first bandpass filter 31 is 10 kHz, the cutoff frequency fc2 of the second bandpass filter 32 is 50 kHz, and the cutoff frequency fc3 of the third bandpass filter 33 is 100 kHz.

  Now, when the user switches the frequency setting switch 8 to a frequency setting of 50 kHz to 450 kHz, the filter changeover switch SW1 is switched according to the control signal from the control circuit 6, and the coupling circuit 2 and the second bandpass filter 32 are switched. Is connected. Then, the cutoff frequency in the reception filter circuit 3 becomes fc2, and the signal output from the reception filter circuit 3 to the reception circuit 4 is reduced in frequency components less than 50 kHz, and thus the level of noise having a frequency less than 50 kHz is reduced. Is done. This suppresses saturation of the output signal of the receiving circuit 4 due to, for example, noise emitted from the electrical device 109, for example, because the signal voltage input to the amplifier in the receiving circuit 4 exceeds the rated voltage of the amplifier. The influence of noise is reduced, and the communication state by the power line communication device 1 can be improved.

  Further, when the user switches the frequency setting switch 8 to a frequency setting of 100 kHz to 450 kHz, the filter switching switch SW1 is switched in accordance with a control signal from the control circuit 6, and the coupling circuit 2 and the third bandpass filter 33 are switched. Is connected. Then, the cutoff frequency in the reception filter circuit 3 becomes fc3, and the signal output from the reception filter circuit 3 to the reception circuit 4 is reduced in frequency components less than 100 kHz, and thus the level of noise having a frequency less than 100 kHz is reduced. Is done. Thereby, the noise level in a wider frequency range is reduced than when the frequency setting switch 8 is set to a frequency setting of 50 kHz to 450 kHz, and the communication state in the power line communication device 1 can be improved.

  When the user switches the order setting switch 9 to the setting of the secondary filter, the switch SW21 is turned off according to the control signal from the control circuit 6, the switch SW23 is switched to the poles P11 and P12, and the reception filter circuit 3 Becomes a second order filter. When the user switches the order setting switch 9 to the setting of the tertiary filter, the switch SW21 is turned on in accordance with the control signal from the control circuit 6, the switch SW22 is turned off, and the switch SW23 is switched to the poles P21 and P22. The reception filter circuit 3 is a third order filter. Further, when the user switches the order setting switch 9 to the setting of the fourth order filter, the switch SW21 is turned on according to the control signal from the control circuit 6, the switch SW22 is turned on, and the switch SW23 is switched to the poles P31 and P32. The reception filter circuit 3 is a fourth order filter.

  In this case, the frequency characteristics of the first bandpass filter 31, the second bandpass filter 32, and the third bandpass filter 33 increase as the filter order of the reception filter circuit 3 increases, so that the attenuation gradient increases and the passband is changed from the attenuation band. The transition to becomes steep. Accordingly, the user can increase the steepness of frequency selection by setting the filter order so as to increase the order using the order setting switch 9, and the noise level of the frequency in the transition region in the filter is reduced. The communication state in the power line communication device 1 can be improved.

  Further, when the cutoff frequency in the reception filter circuit 3 is increased by switching the frequency setting switch 8 by the user, the signal power received by the reception circuit 4 is reduced and the S / N is reduced. In many cases, the noise is output only for a certain period. Therefore, when the electric device 109 is not operating, the user sets the frequency setting switch 8 in a direction in which the cutoff frequency decreases (from fc3 to fc2, from fc2 to fc1). S / N can be improved by changing the setting to).

  Moreover, since the impedance of the power line communication apparatus 1 seen from the power line 101 increases by increasing the impedance of the reception filter circuit 3, for example, even if the number of power line communication apparatuses 1 connected to the power line 101 increases, It is suppressed that the impedance of the lamp line 101 is lowered by the input impedance of the power line communication device 1.

  In addition, although the example which sets the pass band of the reception filter circuit 3 by switching the 1st band pass filter 31, the 2nd band pass filter 32, and the 3rd band pass filter 33 with a changeover switch was shown, for example, The two-band pass filter 32 and the third band-pass filter 33 are not provided. The capacitors C2 and C3 in the first band-pass filter 31 are variable capacitors, and the capacitances of the capacitors C2 and C3 are changed. It is good also as a structure which sets a pass band.

  Further, although an example has been shown in which the control circuit switches the filter changeover switch SW1 according to the setting contents of the frequency setting switch 8, a switch that can be directly switched by the user may be used as the filter changeover switch SW1.

  Moreover, although the frequency band set by the frequency setting switch 8 has been shown as examples of 10 kHz to 450 kHz, 50 kHz to 450 kHz, and 100 kHz to 450 kHz, these are merely examples, and other frequency bands may be used. Good.

  Moreover, although the example provided with three band pass filters was shown, it is sufficient that at least two band pass filters are provided.

(Second Embodiment)
Next, a power line communication apparatus according to the second embodiment of the present invention will be described. FIG. 4 is a block diagram showing an example of the configuration of the power line communication device 1a according to the second embodiment of the present invention. The power line communication device 1a shown in FIG. 4 is different from the power line communication device 1 shown in FIG. 1 in the following points. That is, in the power line communication device 1a shown in FIG. 4, a series circuit of a capacitor C4 and a switch SW3 is connected in parallel with the capacitor C1 in the coupling circuit 2a. In the coupling circuit 2a, for example, the capacitor C1 is 0.1 μF to 0.01 μF, and the capacitance of the capacitor C1 + capacitor C4 is set to about 0.47 μF.

  The switch SW3 is turned on / off in response to a control signal from the control circuit 6a. The control circuit 6a turns on the switch SW3 when transmitting data to the other power line communication device 1 via the power line 101, and connects the capacitor C4 to the capacitor C1 in parallel, so that the transformer T, the power line 101, Is increased, that is, the capacity of the capacitor that cuts the power supply component in the signal acquired from the power line 101 is increased, while the switch SW3 is turned off when receiving data transmitted through the power line 101. By separating the capacitor C4 from the capacitor C1, the capacitance of the capacitor between the transformer T and the lamp line 101 is reduced.

  FIG. 5 is a graph showing an example of frequency characteristics in the coupling circuit 2a. In the graph of FIG. 5, the horizontal axis represents the frequency f [kHz], and the vertical axis represents the input voltage Vi from the lamp line 101 and the Vo / Vi [dB] when the secondary side output voltage Vo of the transformer T is used. Yes. At the time of transmission, that is, when the switch SW3 is turned on, the cut-off frequency fc4 of the coupling circuit 2a is, for example, 10 kHz. On the other hand, when the switch SW3 is turned off, the cut-off frequency fc5 of the coupling circuit 2a Is, for example, 100 kHz.

  Since the other configuration is the same as that of the power line communication apparatus 1 shown in FIG. 1, the description thereof will be omitted, and the characteristic points of the present embodiment will be described below.

  First, when data is transmitted from the control circuit 6a, the switch SW3 is turned on by the control circuit 6a. As a result, the capacitance of the capacitor between the transformer T and the lamp line 101 is increased, so that the output impedance of the coupling circuit 2a with respect to the lamp line 101 is lowered. A signal containing data is output from the control circuit 6 to the modem, modulated by the modem 5, amplified by the transmission circuit 7, and superimposed on the commercial power supply AC100V in the lamp line 101 via the coupling circuit 2. Data is transmitted to another power line communication device via the power line 101. In this case, since the output impedance of the coupling circuit 2a is reduced, a signal containing transmission data is easily superimposed on the commercial power supply AC100V in the lamp line 101.

  Further, in this case, as shown in FIG. 5, the cutoff frequency of the coupling circuit 2a is set to fc4 (10 kHz) so that it can be output to the power line 101 up to a low frequency of the transmission signal.

  Next, when the control circuit 6a is in a data reception waiting state, the switch SW3 is turned off by the control circuit 6a. As a result of the reduction of the capacitor capacity between the transformer T and the lamp line 101, the cutoff frequency of the coupling circuit 2a is set to fc5 (100 kHz) as shown in FIG.

  When the power line communication signal is superimposed on the commercial power supply AC100V from another powerline communication device in the power line 101, a signal superimposed on the commercial power supply AC100V is acquired from the power line 101 by the coupling circuit 2. A signal in which the frequency component less than the cut-off frequency fc5 (100 kHz) is reduced, that is, a signal in which the noise level having a frequency less than 100 kHz is reduced is output to the control circuit 6a via the reception filter circuit 3 and the modem 5. Then, the data is received by the control unit 6a.

  As a result, at the time of transmission, the output impedance of the coupling circuit 2a is lowered, the signal containing the transmission data is easily superimposed on the commercial power supply AC100V on the lamp line 101, and the cut-off frequency of the coupling circuit 2a is lowered for transmission. While outputting to the power line 101 up to the low frequency of the signal, at the time of reception, the cut-off frequency of the coupling circuit 2a can be increased, and the noise level can be reduced in a frequency range of less than 100 kHz where there is a lot of noise. The communication state in the device 1 can be improved.

(Third embodiment)
Next, a power line communication apparatus according to the third embodiment of the present invention will be described. FIG. 6 is a block diagram showing an example of the configuration of the power line communication device 1b according to the third embodiment of the present invention. The power line communication device 1b shown in FIG. 6 is different from the power line communication device 1 shown in FIG. 1 in the following points. That is, in the power line communication device 1b shown in FIG. 6, the number of turns of the primary winding 21 of the transformer T is n1 in the coupling circuit 2b. On the other hand, the secondary winding 22a of the transformer T has n3 windings, and an intermediate tap P4 is provided at a position where the number of windings is n2. There is a relationship of n3> n2 = n1 between the numbers of windings.

  One end of the secondary winding 22a is connected to the reception filter circuit 3 and the transmission circuit 7, and the other end is connected to the pole P5. The coupling circuit 2b includes a switch SW4 that connects either the intermediate tap P4 or the pole P5 to the reception filter circuit 3 and the transmission circuit 7 in accordance with a control signal from the control circuit 6b.

  The control circuit 6b switches the switch SW4 to connect the pole P5, the reception filter circuit 3 and the transmission circuit 7 when receiving data sent via the power line 101. On the other hand, the control circuit 6b switches the switch SW4 to connect the intermediate tap P4, the reception filter circuit 3, and the transmission circuit 7 when data is transmitted to the other power line communication device 1 via the lamp line 101. As a result, the number of secondary windings 22a is increased to n3 at the time of reception to be n3, and the number of secondary windings 22a is reduced at the time of transmission to be less than at the time of reception. The volume is n2.

  Since the other configuration is the same as that of the power line communication apparatus 1 shown in FIG. 1, the description thereof will be omitted, and the characteristic points of the present embodiment will be described below.

  First, an operation when data transmitted via the power line 101 is received by the power line communication device 1b will be described. When the data sent via the power line 101 is received by the power line communication device 1b, the switch SW4 is switched to the pole P5 side by the control circuit 6b, and the number of turns of the secondary winding 22a is n3. It is said. Then, since the winding number ratio of the transformer T is n1: n3 and the winding number ratio is larger than 1, the reception impedance of the power line communication device 1b as viewed from the lamp line 101 side winds the impedance of the reception filter circuit 3. The value is divided by the square of the number ratio.

  Then, for example, when the winding number ratio of the transformer T is 1: 1 as compared with the case where the winding number ratio of the transformer T is 1: 1, the power line communication device viewed from the lamp line 101 side. While the reception impedance of 1b is the impedance of the reception filter circuit 3, when the number of turns of the secondary winding 22a is n3 by the control circuit 6b, the power line communication device 1 viewed from the lamp line 101 side. , Which is obtained by dividing the impedance of the reception filter circuit 3 by the square of the winding ratio larger than 1, the reception impedance is reduced.

  As a result, the reception impedance of the power line communication device 1b is reduced at the time of reception, so that, for example, the signal voltage input to the amplifier in the reception circuit 4 exceeds the rated voltage of the amplifier due to noise emitted from the electrical device 109, for example. As a result, saturation of the output signal of the reception circuit 4 is suppressed, and the reception state of the power line communication device 1b can be improved.

  Next, an operation when data is transmitted from the control circuit 6b will be described. In this case, when the turns ratio of the transformer T is n1: n3 as in reception, the signal voltage output from the coupling circuit 2b to the lamp line 101 is output from the transmission circuit 7 to the coupling circuit 2b. Therefore, the signal voltage output from the coupling circuit 2b to the lamp line 101 is lowered.

  Therefore, when data is transmitted from the control circuit 6b, the switch SW4 is switched to the intermediate tap P4 side by the control circuit 6b, and the number of turns of the secondary winding 22a is n2. Then, since the winding number ratio of the transformer T is n1: n2 and the winding number ratio is 1, the transmission is performed in a state where the winding number ratio of the transformer T is n1: n3 as in reception. As compared with the above, it is possible to suppress the signal voltage superimposed on the lamp line 101 from the coupling circuit 2b from being lowered.

  Although the case where the number of windings of the transformer T is n3> n2 = n1 is shown, it is only necessary that n3> n2, and it is not limited to the case where n2 = n1.

(Fourth embodiment)
Next, a power line communication apparatus according to the fourth embodiment of the present invention will be described. FIG. 7 is a block diagram showing an example of the configuration of a power line communication device 1c according to the fourth embodiment of the present invention. The power line communication device 1c shown in FIG. 7 is different from the power line communication device 1b shown in FIG. 6 in the following points. That is, in the power line communication device 1c shown in FIG. 7, the intermediate tap P4 of the secondary winding 22a and the transmission circuit 7 are fixedly connected. The coupling circuit 2c includes a switch SW5 that connects either the intermediate tap P4 or the pole P5 to the reception filter circuit 3 in accordance with a control signal from the control circuit 6c, instead of the switch SW4 in the coupling circuit 2b.

  Further, the winding changeover switch 10 is connected to the control circuit 6c. The winding changeover switch 10 is a setting switch for accepting a winding changeover instruction from a user for changing over the number of turns of the secondary winding 22a connected to the reception filter circuit 3 by changing over the switch SW5. It consists of dip switches and the like. Then, the control circuit 6 c switches the connection of the switch SW <b> 5 according to the setting state of the winding changeover switch 10.

  Since the other configuration is the same as that of the power line communication device 1b shown in FIG. 6, the description thereof will be omitted, and the characteristic points of the present embodiment will be described below.

  First, when the winding changeover switch 10 is set by the user to connect the switch SW5 to the pole P5, the switch SW5 is connected to the pole P5 according to the control signal from the control circuit 6c, and the reception filter circuit 3 is connected. The number of turns of the secondary winding 22a to be connected is n3. When the data sent via the power line 101 is received by the power line communication device 1c shown in FIG. 7, the power line communication device is received in the same manner as when received by the power line communication device 1b shown in FIG. Since the reception impedance of 1c is reduced, for example, noise emitted from the electric device 109 causes the signal voltage input to the amplifier in the reception circuit 4 to exceed the rated voltage of the amplifier, for example. Is suppressed, and the reception state by the power line communication device 1c can be improved.

  When data is transmitted from the control circuit 6b, the winding number ratio of the transformer T is n1: n2 as in the case of transmission by the power line communication device 1b shown in FIG. It can be suppressed that the signal voltage superimposed on the line 101 is lowered.

  Furthermore, unlike the power line communication device 1b shown in FIG. 6, when receiving and transmitting, there is no need to switch the switch SW4 and change the winding ratio of the transformer T each time, so that the control circuit 6c Can be simplified.

  In addition, when the noise emitted from the electrical device 109 to the power line 101 is reduced, for example, when the electrical device 109 is not operating, the user sets the winding changeover switch 10 to be connected to the intermediate tap P4. Thus, the switch SW5 is connected to the intermediate tap P4 according to the control signal from the control circuit 6c, and the number of windings of the secondary winding 22a connected to the reception filter circuit 3 is n2. Thereby, the reception impedance of the power line communication device 1c viewed from the power line 101 at the time of reception can be increased, and a decrease in received signal level due to a decrease in reception impedance can be suppressed.

It is a block diagram which shows an example of a structure of the power line communication apparatus which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows an example of a structure of a 1st band pass filter, a 2nd band pass filter, and a 3rd band pass filter. It is a graph which shows an example of the frequency characteristic in a 1st band pass filter, a 2nd band pass filter, and a 3rd band pass filter. It is a block diagram which shows an example of a structure of the power line communication apparatus which concerns on the 2nd Embodiment of this invention. It is a graph which shows an example of the frequency characteristic in the coupling circuit shown in FIG. It is a block diagram which shows an example of a structure of the power line communication apparatus which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows an example of a structure of the power line communication apparatus which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the structure of the power line communication apparatus which concerns on background art. It is a block diagram for demonstrating the apparatus connected to the power line.

Explanation of symbols

2, 2a, 2b, 2c Coupling circuit (coupling unit)
3 Reception filter circuit (Reception filter section)
4 Receiver circuit (receiver)
5 Modem 6, 6a, 6b, 6c Control circuit 7 Transmission circuit 8 Frequency setting switch 9 Order setting switch 10 Winding switch 21 Primary winding 22, 22a Secondary winding 31 First band pass filter 32 Second band pass filter 33 Third Band Pass Filter 101 Electric Power Line (Power Line)
C1, C4 Capacitor SW1 Filter switch (Setting part)
SW2, SW5 switch SW3 switch (capacitance switching unit)
SW4 switch (winding number switching part)
T transformer

Claims (7)

In a power line communication device that performs communication using a power line shared for power supply and communication,
A coupling unit for transmitting and receiving signals to and from the power line;
A transmission unit for transmitting a signal containing data to the power line via the coupling unit;
A reception filter unit that selectively passes a signal in a predetermined frequency range from the signal output from the coupling unit;
A receiving unit that acquires data from a signal that has passed through the reception filter unit;
A power line communication apparatus comprising: a setting unit configured to set the predetermined frequency range.   The power line communication apparatus according to claim 1, wherein a lower limit value in the predetermined frequency range is 10 kHz to 100 kHz. The reception filter unit includes a plurality of bandpass filters having different frequency bands, and a switch for selecting any of the plurality of bandpass filters,
The power line communication apparatus according to claim 1, wherein the setting unit switches the switch. The plurality of band pass filters are ladder-type LC filters;
The power line communication apparatus according to claim 3, wherein the setting unit switches the order of the ladder LC filter. The coupling unit includes a capacitor that cuts a power supply component in a signal acquired from the power line, a transformer in which the capacitor and a primary winding are connected in series, and a secondary winding connected to the reception filter unit and the transmission unit. A capacitance switching unit that increases or decreases the capacitance of the capacitor,
The capacitance switching unit increases the capacitance of the capacitor when data is transmitted from the transmission unit, and decreases the capacitance of the capacitor when data is acquired by the reception unit. Item 5. The power line communication device according to any one of Items 1 to 4. The coupling unit includes a capacitor that cuts a power supply component in a signal obtained from the power line, a transformer in which the capacitor and a primary winding are connected in series, and the reception filter unit and the secondary winding in the transformer. A winding number switching unit for increasing or decreasing the number of windings connected to the transmission unit;
The winding number switching unit increases the number of windings when data is acquired by the receiving unit, and decreases the number of windings when a signal containing data is transmitted from the transmission unit. The power line communication device according to claim 1, wherein the power line communication device is a power line communication device. The coupling unit includes a capacitor that cuts a power supply component in a signal acquired from the power line, a transformer in which a primary winding is connected in series with the capacitor, and a secondary winding is connected to the reception filter unit and the transmission unit. And
The number of windings connected to the reception filter unit among the secondary windings in the transformer is larger than the number of windings connected to the transmission unit. The power line communication apparatus according to any one of the above.

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