JPH1141151A - Lighting line carrier communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain voltage at transmission/reception ends of the communication equipment as high and to continue good communication even when impedance of a lighting line is varied. SOLUTION: An impedance varying means 102 is connected between the communication equipment 100 and the lighting line L. The impedance ZL of the lighting line is measured before starting the communication by an impedance measurement means 103. Variable impedance of the impedance varying means 102 is adjusted from the measured impedance so that the voltage VS at the transmission/reception ends becomes the maximum by an impedance adjustment means 104. Consequently, the communication is performed with large amount of the voltage at the transmission/reception ends even when an electric equipment is connected with the lighting line L1 and the impedance of the lighting line L1 is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power line communication device for transmitting a carrier wave signal superimposed on a power line.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional power line communication device.
This will be described with reference to FIG. FIG. 1 is a diagram showing a state where a transmitter is connected to a power line, and FIG. 2 is a diagram showing a state where a receiver is connected to a power line. In FIG. 1, T is a transmitter, which is connected to the power line L and transmits a signal to the power line L.
The point at which the transmitter T is connected to the power line L is called a transmitting / receiving end aa
Call. E _T represents the signal source voltage of the transmitter, and Z _T represents the output impedance of the transmitter T. Z _L represents the impedance of the power line L.

[0003] In the transmitter T, the signal is output on the power line L.
Signal value, that is, transmitting / receiving end voltage V _STo increase
The impedance Z of the light line L_LTransmitter T
Output impedance Z_TIs a low value. In FIG.
R is a receiver and connected to the power line L at the transmitting / receiving end aa.
Subsequently, a signal transmitted from the power line L is received.
Z_RRepresents the impedance of the receiver R.

[0004] In the receiver R, the value of the signal to be received,
That is, in order to increase the transmission / reception end voltage V _S and increase the reception efficiency, the impedance Z _R of the receiver _{R is set} to several hundreds Ω and higher than the impedance Z _{L of the} power line. In the conventional power line communication device, by determining the impedance value of the transmitter T or the receiver R as described above, the signal of the transmitter T reaches the receiver R without being attenuated as much as possible. The communication between the T receivers R has been enabled.

[0005] As a communication device used in the power line communication device, there is a transceiver in addition to the transmitter T and the receiver R described above. For transceiver selects and sets the impedance Z _T and Z _R in accordance with the respective functions of transmission or reception.

[0006]

By the way, since various electric appliances are connected to and disconnected from the electric light line L, the impedance Z _L of the electric light line L changes depending on the connection state and use state of the electric equipment. Thus, the transmission characteristics change depending on the situation. In contrast, in the conventional method, and the value of any fixed impedance Z _R of the output impedance Z _T and the receiver R of the transmitter T. For this reason,
As described above, it has not been possible to adapt to the fact that the transmission characteristics of the power line change depending on the situation.

For example, an electric appliance having a capacitor component has a low impedance with respect to a carrier signal. Therefore, when this device is connected to the power line, the power line L
The impedance Z _L decreases in the vicinity of. When the transmitter T is connected to the power line having the reduced impedance Z _L , the output impedance of the transmitter T becomes relatively high. _S decreases.

[0008] In the case of the receiver R is A low impedance Z _L of the impedance Z _R is higher in power line L of the receiver R is, the voltage reaching also low, also transmit and receive end voltage V _S is descend. As a result, there arises a problem that communication between the transmitter T and the receiver R becomes impossible.
In contrast, even in an environment in which the impedance Z _L of the power line L is changed, if it is possible to maintain a high transmission and reception end voltage V _S, it is possible to perform a good communication between the receiver R and transmitter T .

The present invention relates to a power line communication device,
It is an object of the present invention to maintain a high transmission / reception end voltage of a communication device and maintain good communication even if the impedance of a power line changes.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. The basic configuration of the present invention will be described with reference to FIG. In FIG. 3, reference numeral 100 denotes a communication device such as a transmitter, a receiver, or a transceiver.
At -a, it is connected to the power line L. V _S is the transmitting / receiving end a
This is a transmission / reception end voltage appearing between −a. Z ₀ is the communication device 10
0 represents an impedance, and Z _L represents the impedance of the power line L. Incidentally, if the communication device 100 is a transmitter, as shown in FIG. 1 described above, so that the signal source voltage E _T present in series with the impedance Z _L.

An impedance changing means 102 for changing the transmission / reception end impedance of the power line L is provided. The impedance changing means 102 changes the impedance of the power line L at the transmitting / receiving end aa by connecting the impedance element to the power line L in series or in parallel. Further, an impedance measuring unit 103 for measuring the impedance Z _L of the power line L, are provided with impedance-adjusting means 104.

When the impedance Z _L of the power line L fluctuates due to connection or disconnection of an electric appliance or the like to or from the power line L, the value of the impedance measured by the impedance measuring means 103 fluctuates. The impedance adjusting unit 104 controls the impedance changing unit 102 based on the measured impedance so that the transmission / reception end voltage V _S becomes a predetermined value. As a result, even if the impedance Z _L of the power line L fluctuates, the transmission / reception voltage V _S of the communication device 100 can be kept high, and good communication can always be performed.

The timing at which the impedance adjusting means 104 controls the impedance changing means 102 can be immediately before the communication device 100 sends a signal. Alternatively, it can be performed at predetermined time intervals. Here, the predetermined time interval refers to a fixed time interval, a randomly determined time interval, or the like. Also, when a plurality of communication devices having the above-described impedance adjustment function are connected to a power line,
The impedance of the communication device is changed by the adjustment function, and the impedance of another communication device whose adjustment has already been completed may be deviated from the optimum value due to the influence. If the impedance adjustment is performed again in the disengaged communication device, this further de-adjusts the other communication devices.
As described above, when the adjustment work is repeated in each communication device, communication may not be started without completing the adjustment work in a short time. In the present specification, this is referred to as “adjustment oscillation”.

In order to prevent the oscillation of the adjustment, the adjustment work can be converged by providing a condition for terminating the optimum adjustment in each communication device 100. In particular,
When the transmission / reception end voltage or the transmission / reception end impedance becomes higher than a certain threshold value, the optimum adjustment operation ends. Alternatively, when the difference between the value of the transmission / reception end impedance or the value of the transmission end voltage before and after the adjustment is reduced during the adjustment work, the optimum adjustment work is ended.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
Shows the configuration of the power line communication system to which the communication device is applied.
FIG. In FIG. 4, L is a power line, and this light
Communication equipment such as transmitter T, receiver R, transceiver TR on line L
Are connected via a connection box B. Each communication device
The power line L is used as a carrier signal transmission path, and
Do the trust. A is an electric load connected to the power line L.
This electric load A is the capacitance of fluorescent lighting equipment and the like.
Component, the power line L
Impedance Z _LMay decrease. Light line L
Impedance Z_LThe electric negative
Transmission / reception end voltage V near load A_SIs the electric load A
Transmitter end voltage V when not connected_S0Lower.

Hereinafter, various embodiments of the present invention will be described. However, the description of the transmitter T and the receiver R is also applicable to the transmitter and the receiver of the transceiver TR. . (Embodiment 1) An example of connecting an impedance changing element in series with a power line when connecting a transmitter to a power line will be described with reference to FIGS.

FIG. 5 is a diagram showing a circuit configuration of the first embodiment. In FIG. 5, L is a power line, and Z _L is the impedance of the power line L. The power line impedance Z _L is
Represented by _{Z L = R L + jX L} . Transmission / reception end a of power line L
The transmitter T is connected to -a. The transmitter T includes a carrier generation unit 1, an impedance adjustment unit 2, a measurement circuit unit 3, and a calculation unit 4. Each part 1 to 4 of the transmitter T may be formed integrally or separately.

The carrier generating unit 1, a signal source, including such as a filter circuit, the signal source voltage E _T and the output impedance Z
Represented by _{T (R T + jX T)} . The impedance adjuster 2 includes a variable inductance 7 connected in series to the carrier generator 1 and the transmitting / receiving end a. The measuring circuit unit 3 includes a voltage measuring device 10 for measuring a voltage between the transmitting and receiving terminals a and a reference resistor R connected in series to the carrier generating unit 1 and the transmitting and receiving terminals a.
_{It comprises an ST} and a voltage measuring section 11 for measuring the voltage across the _ST . Therefore, one of the voltage measuring device 10 measures the voltage V ₂ of the impedance Z _L of the power line, other voltage measuring device 11 measures the voltages V ₁ proportional to the current flowing through the impedance Z _L.

As the reference resistor R _ST , a resistor having a value as small as possible (for example, about 1Ω) is used for the purpose of not lowering the signal output to the power line L. The two voltage measuring units 10 and 11 have a sufficiently large value (eg, 10 kΩ) as compared with the impedance Z _{L of the} power line so that the measurement is hardly affected.
An input impedance of about (approximately) is appropriate.

The arithmetic section 4 has a function based on the measured value of the measuring circuit section 3.
The impedance Z of the power line L _LThe phase of
Phase comparator 12 and impedance Z_LCalculate the absolute value of
An absolute value calculator 13 is provided. Reactance component
The arithmetic unit 14 calculates a later-described method from the phase and absolute value obtained here.
The power line impedance Z_LReactance component of
X_LIs calculated. Variable inductance first set value calculator
16 is the reactance component X_LAnd stored in the storage unit 15
Output impedance Z_TReactance component X of_TWhen
From the transmission end voltage V_SVariable inductor so that
Set value X of reactance 7_ATo calculate the variable inductance
7 is the value X_AImpedance adjustment unit 2 so that
Control. The arithmetic unit 4 includes a microcomputer and a digital circuit.
It can also be realized by a circuit or an analog circuit.

Next, the set value X of the variable inductance 7_A
The following describes how to obtain the value. Transmission and reception in the circuit of FIG.
Terminal voltage V_SIs represented by the following [Equation 1]. Where R _STIs
It should be small enough.

[0022]

(Equation 1)

Note that R _A is a resistance component of the impedance adjusting unit 2, but in the circuit of FIG. 5, R _A = 0. In this equation (1), the resistance component R _A, by setting the reactance component X _A to the value of the next expression (2) Formula 3, transmission and reception end voltage V _S is the maximum value.

[0024]

(Equation 2)

[0025]

(Equation 3)

Therefore, for example, when it is a problem that the electric load of the capacitance component is connected to the power line L and the signal output is reduced, the value of the variable inductance 7 of the impedance adjusting unit 2 is changed to X _A of [Equation 3]. , The signal level (transmitter / receiver terminal voltage V _S ) can be increased. FIG. 6 is a flowchart illustrating the operation of the arithmetic unit 4 of the circuit of FIG.

The operation of this example is performed before the transmission by the transmitter T is started. In step S61, the impedance Z _L of the power line _L is measured. Power line impedance Z _L
And its phase Φ are obtained by the following [Equation 4] and [Equation 5].

[0028]

(Equation 4)

[0029]

(Equation 5)

From this, the reactance component X of the power line L
_L is obtained by the following [Equation 6].

[0031]

(Equation 6)

In step S62, the variable inductance 7
Calculating the set value X _A. Reactance component X _T of output impedance Z _T measured in advance and stored in storage unit 15
And the power line impedance Z _L calculated by the calculator 14
Using a variable inductance first set value calculator 16 from the reactance component X _L in, calculates the set value X _A of the variable inductance 7 performs an operation of the aforementioned Formula 3.

Finally, in step S63, the arithmetic unit 4
It is controlled to be the set value X _A calculated variable inductance 7 of the impedance adjusting portion 2. Thus, by adjusting the inductance is set to the value of the expression (2) and Formula 3 described above, it may be a maximum value of receiving-end voltage V _S shown in equation (1). Therefore, by starting transmission after this setting, good communication is performed.

As a method of realizing the variable inductance 7, a method of preparing several inductances having discrete values and switching mechanically according to set values, or a method of preparing and switching some semiconductor inductances Alternatively, there is a method of electronically switching the semiconductor inductance. When a variable capacitance is used as the adjustment impedance, a capacitor or a semiconductor capacitor can be used in the same manner as described above. (Embodiment 2) An example in which an impedance changing element is connected in parallel with a power line when a transmitter is connected to a power line will be described with reference to FIG.

FIG. 7 is a diagram showing a circuit configuration of the second embodiment. FIG. 7 has a lot of overlap with FIG. 5 described above.
In the following, the points different from FIG. 5 will be mainly described, and overlapping parts will be described briefly. The impedance adjustment unit 2 of this example is connected in parallel with the power line L at the transmitting / receiving ends aa. The variable inductance 7 in order to protect from a commercial power source, protective capacitor C _K are connected in series. The variable inductance 7 is initially set in an open state.

In the measuring circuit 3, the voltage measuring device 10 measures the voltage between the transmitting and receiving terminals aa. The reference resistor R _ST is connected in series to the carrier generator 1 and the transmitting / receiving end a. When variable inductance 7 is opened, the first voltage measuring device 10 measures the voltage V ₂ of the impedance Z _L of the power line, other voltage measuring instrument 11 is a voltage proportional to the current flowing through the impedance Z _L to measure the V _1.

In the operation unit 4, in addition to the reactance component operation unit 14, the phase comparator 12 and the absolute value operation unit 13
From the phase and absolute value obtained from
Resistance component calculator 17 for calculating the resistance component R _L of _L are provided. The storage unit 25, the capacitance of protective capacitor C _K of the impedance adjusting portion 2 is stored. To calculate the setting value X _A of the variable inductance 7 from the R _L and X _L and C _K, variable inductance second setting value computation unit 1
8 is used.

Next, the set value X _{A of the} variable inductance 7
The following describes how to obtain the value. To compensate for the reduction of the power line L of impedance _{Z L (= R L + jX} L) may be a parallel resonant circuit with the impedance Z _L and the variable inductance 7 of the power line. For example, the resistance component R _A variable inductance 7 when a 0Ω by setting the reactance component X _A to the value of the next [Equation 7], high transmission and reception end voltage V _S appearing on receiving end a-a can do.

[0039]

(Equation 7)

However, since a protection capacitor C _K is actually connected in series with the adjustment impedance 7, if the capacitance of the capacitor is C _K [F], then [Equation 7] becomes the following [Equation 8]. ].

[0041]

(Equation 8)

Here, f is the signal frequency. In addition,
[Equation 7] and [Equation 8] are the impedance Z _{L of the} power line _L.
Reactance component X _L of an equation for determining the adjustment inductance when not zero. When _XL is 0, [Equation 7] and [Equation 8] become indefinite, so that the impedance is set to a predetermined value. For example, in the case where an electric appliance having a capacitor component is connected to the power line L and the signal output decreases, the signal output can be increased by using an inductance of the value of [Equation 8] for the adjustment impedance 7.

The variable inductance second set value calculator 18 of the operation section 4, a resistance component R _L and the reactance component X _L of the impedance Z _L of the resistive component calculator 17 and the reactance component calculator 14 from obtained electric power line, and a capacitance C _K of the protective capacitor stored in the storage unit 25 by using the [equation 8] calculates the setting value of the variable inductance X _a. The operation of the circuit of FIG. 7 is performed in the same manner as in the above-described flowchart of FIG.

In step S61, the impedance Z _{L of the} power line is measured. In this embodiment, not only the reactance component X _L but also the resistance component R _L are obtained. The reactance component X _L obtained in the above-mentioned [6], the resistance component R _L is calculated by the following [Equation 9].

[0045]

(Equation 9)

[0046] At step S62, the variable inductance second set value calculator 18 calculates the set value X _A using [Equation 8] described above. Finally, in step 63, it is controlled to be the set value X _A calculated value of the variable inductance 7 of the impedance adjusting portion 2. (Embodiment 3) An example in which a receiver is connected to a power line and an element for changing impedance is connected in parallel with the power line L will be described with reference to FIG.

FIG. 8 is a diagram showing a circuit configuration of the third embodiment.
is there. FIG. 8 shows a portion that overlaps with FIG. 7 of the second embodiment.
In the following, points different from FIG.
It is explained in mind, and overlapping parts will be explained briefly. In FIG.
And R is a receiver, which adjusts the impedance with the receiver 5.
Unit 2, a measurement circuit unit 3, and a calculation unit 4,
It is connected to the transmitting / receiving end aa of the light line L. The receiving unit 5 includes
Impedance Z as the value circuit_RHaving. Again
Impedance Z of power line L_LMeasurement signal source (signal power
Pressure E_M, Output impedance Z _M) The receiver impeder
Z_RHold the switch in parallel with
The carrier is injected by switching. Impedance
The adjustment unit 2, the measurement circuit unit 3, and the calculation unit 4 are the same as those in FIG.
It is composed of

In this embodiment, the second embodiment (FIG.
As in 7), the impedance Z of the power line_LAnd variable in
Transmission and reception by configuring parallel resonance with the conductance 7
Terminal voltage V_SHigher. Therefore, in the arithmetic unit 4,
Is the same as that of the second embodiment.
Value X_ASet. The operation of this embodiment is the same as that of the second embodiment.
Similarly, the processing is performed according to the flowchart of FIG. However
However, the receiver R needs to know in advance when the signal should be received.
Is connected to the power line L and is always in a receivable state.
Is what it is. Therefore, in the flowchart of FIG.
The action shown is a fixed time interval or a randomly determined time
This is performed at intervals, that is, at predetermined time intervals. (Embodiment 4) In Embodiments 1 to 3,
Transmit / receive end voltage V _SHas been improved
There may not be. For example, originally a power line impedance
Z _LIs not low or the impedance Z_LMeasurement
Cannot be performed correctly, or the light is
Wire impedance Z_LIs changed.
In such a case, do not adjust the impedance.
It is preferable to start communication.

In this case, the operation section 4 performs the operation shown in FIG. 9 instead of the operation in the flowchart of FIG. The operation in FIG. 9 is executed immediately before the start of communication in the case of a transmitter, and is executed at a fixed time interval or a time interval determined at random, that is, at a predetermined time interval in the case of a receiver. In step S901, the transmission / reception end voltage V _S before the adjustment of the variable inductance 7 is measured. Thereafter, in steps S61 to S63, the impedance adjustment unit 2 is adjusted by the method described above. After this adjustment, in step S902, the measured transmitting and receiving end voltage V _S.

In step S 903, it is determined whether the adjusted transmission / reception end voltage V _S measured in step 902 is higher than the pre-adjustment transmission / reception end voltage V _S measured in step 901. If it is higher here, it is determined that effective impedance adjustment has been performed, and communication is started with the impedance adjusted. On the other hand, if not higher, it is determined that the impedance adjustment was not effective,
In step S904, the setting of the variable inductance 7 is canceled (the variable inductance 7 is separated). Thereafter, the transmitter starts transmission, and the receiver waits for reception.

[0051] In the above in the example described, although control is performed based on the adjusted comparison of the previous transmission and reception end voltage V _S and the receiving end voltage V _S of the adjusted instead of sending and receiving end voltages V _S, lamp It is also possible to control based on a comparison of the line impedance Z _L. (Embodiment 5) Embodiment 5 is intended to prevent oscillation of adjustment. The regulation oscillation will be described again here.
When a communication device with an impedance adjustment function is connected to multiple power lines, the impedance of the communication device changes due to the adjustment function, and the impedance of the other communication devices that have already been adjusted due to the effect will have the optimal value. May deviate from If the impedance adjustment is performed again in the disengaged communication device, this further de-adjusts the other communication devices. As described above, when the adjustment work is repeated in each communication device, communication may not be started without completing the adjustment work in a short time.

FIG. 10 shows a circuit configuration of a power line communication device provided with an oscillation preventing function. Since the circuit of FIG. 10 is obtained by adding an oscillation preventing function to the circuit of FIG. 7 of the second embodiment, the following description focuses on the differences from FIG. explain. In the impedance adjustment section 2, the changeover switch 21 in series is inserted into the protective capacitor C _K a variable inductance 7. Variable inductance 7, as in Embodiment 2, is set to the calculated values X _A by variable inductance second set value calculator 18 of the calculation unit 4.

Carrier modulation section 22, CPU 23, storage section 2
4 is added. The CPU 23 compares the absolute value of the impedance Z _L of the power line calculated by the absolute value calculator 13 of the calculation unit 4 with the threshold value stored in the storage unit 24, and based on the result, switches the changeover switch 21. And the control of the carrier modulation unit 22 is performed. The circuit of FIG. 10 described above is an improvement of the circuit of FIG. 7 of the second embodiment as described above, but a similar function can be added to the circuit of FIG. 9 of the third embodiment.

The operation of the circuit shown in FIG.
This will be described with reference to the flowchart of FIG. In addition, FIG.
A first operation example is shown, and FIGS. 12 and 13 show a second operation example. (Operation Example 1) The operation shown in FIG. 11 is to prevent the oscillation of adjustment based on the value of the impedance Z _L of the power line L as a criterion.

In step S111, the counter in the CPU 23 is cleared. In step S112, the changeover switch 21 is turned on, to measure the impedance of the parallel circuit of the impedance Z _L of the impedance adjusting portion 2 and the power line. In step S113, the CPU 23 compares the absolute value of the impedance of the parallel circuit calculated by the absolute value calculator 13 with the threshold value stored in the storage unit 24. Here, if the absolute value is higher than the threshold value, it is determined that adjustment is not necessary, and the processing is exited and communication is started. That is, the carrier modulation section 22 is operated to start signal transmission. If it is lower, it is determined that adjustment is necessary, and the process proceeds to step S114.

Step S114 and step S115 are
This is a process for preventing the oscillation of the adjustment. This processing will be described later, but in the case of the first processing, step 11
5 to step 61. Steps S61 to S63
The operation is almost the same as that of FIG. In step S61, the changeover switch 21 is opened to change the variable inductance 7
Is not included, the impedance Z _L of the power line is measured. In step S62, it calculates a set value X _A variable inductance 7. In step S63, it sets a variable inductance 7 of the impedance adjusting portion 2 to a set value Z _A.

In step S116, the changeover switch 22 is short-circuited and the variable inductance 7 is inserted, and after waiting for a predetermined time, the process returns to step S112. Less than,
Impedance of the parallel circuit of the impedance Z _L of the variable inductance X _A and power line again of the impedance adjusting unit 2 at step S112 is measured, the measurement values starts communication with the process ends if higher than the threshold value, If the value is lower, the readjustment of the impedance after step S114 is performed.

When the number of times of the re-adjustment, that is, the number of times of the counter reaches a certain value, it is determined that the oscillation of the adjustment has occurred.
The process exits from step 115 and forcibly starts communication.
Therefore, the counter is incremented in step S114, and it is determined in step S115 whether the value of the counter has reached a certain value. As described above, the oscillation of the adjustment of each communication device connected to the power line L is prevented.

The threshold value stored in the storage unit 24 may be a fixed value or a variable value. For example, the variable method can be relatively determined based on the adjusted maximum value of the impedance that can be calculated using the measurement result of the impedance Z _L of the power line L. This point is the same in other embodiments. In addition, although the process waits for a certain time in step 116, the present invention is not limited to this. For example, a random number may be generated and the waiting time may be changed based on the generated random number. (Operation Example 2) The operations shown in FIGS. 12 and 13 show the operation of preventing the oscillation of the adjustment based on the difference between the previous measurement and the current measurement of the impedance Z _L of the power line based on the judgment criterion.

At steps 121 and 122, the counters 1 and 2 in the CPU 23 are cleared. Step 12
At 3, the switch 21 is turned on, and the impedance Z _L of the power line is measured with the variable inductance 7 included. In step 124, the difference ΔZ _L from the previous measurement is obtained.

Steps S125 to S128 are processes for determining whether or not the impedance adjustment has reached saturation. Although details of this processing will be described later, in the case of the first processing, the process proceeds from step S125 to step S129. Steps 129 and 130 are processing for determining that oscillation of adjustment has occurred when a series of adjustment work has been performed a fixed number of times or more, and for exiting the loop. Although details of this processing will be described later, in the case of the first processing, the process proceeds from step S130 to step S61.

Steps 61 to 63 are the same as those in the operation example 1 described above with reference to FIG. When the processing in step S63 to set the variable impedance 7 in the setting value X _A, waits for a predetermined time in step S131, the flow returns to the subsequent step 123. Thereafter, the impedance is measured again after step S123, and the difference ΔZ _{L from the} previous time is obtained at step S124.

In steps S125 to S128, it is determined whether or not the impedance adjustment has reached saturation. In step S125, the difference ΔZ _L is compared with the threshold value stored in the storage unit 24. Here, if the difference ΔZ _L is smaller than the threshold value, the counter 1 is incremented in step S126. When the adjustment is saturated, the difference ΔZ _L becomes smaller,
When the counter 1 continuously reaches a certain number of times, it is determined that the adjustment is saturated in step 127, and the process is terminated and communication is started.

On the other hand, if it is determined in step S125 that the difference ΔZ _L is larger than the threshold value, the adjustment is not saturated. Therefore, the counter 1 is cleared in step S128, and the flow advances to step S129. Steps S129 and S130
Then, the presence or absence of the oscillation of the adjustment is determined. In step S129, the number of adjustments of the variable impedance 7 is counted by the counter 2. When the number of times of the counter 2 reaches a certain value, it is determined that the oscillation of the adjustment has occurred.
Exit from 0 and forcibly start communication. (Embodiment 6) The circuit shown in FIG.
Since the oscillation preventing function is added to the circuit shown in FIG. 5, only the points different from FIG. 5 will be mainly described, and overlapping parts will be described briefly.

A changeover switch 21 is provided in the impedance adjusting section 2 in parallel with the variable inductance 7. Variable inductance 7 is similar to the first embodiment, it is set to the calculated values X _A by variable inductance first set value calculator 16 of the calculation unit 4. Carrier modulation unit 22, CPU2
3. A storage unit 24 is added. The CPU 23 compares the output of the voltage measuring device 10 with the threshold value stored in the storage unit 24, and switches the changeover switch 21 and controls the carrier wave modulation unit 22 based on the result.

FIGS. 15 to 17 show the operation of the circuit of FIG.
This will be described with reference to the flowchart of FIG. In addition, FIG.
A first operation example is shown, and FIGS. 16 and 17 show a second operation example. Operation shown in (operation example 1) FIG. 15 is for preventing oscillation of the adjustment value of the transmitting and receiving end voltage V _S as a criterion.

At step 151, the counter is cleared.
In step 152, the voltage measuring device 10 is set in a state where the changeover switch 21 is turned off and the variable inductance 7 is enabled.
Is used to measure the transmission / reception end voltage V _S. Step 15
In step 3, the CPU 23 compares the measured transmission / reception end voltage V _S with the threshold value stored in the storage unit 24. here,
If the transmission end voltage V _S is higher than the threshold value, it is determined that no adjustment is necessary, and the processing is exited and communication is started. That is, the carrier modulation section 22 is operated to start signal transmission. If lower, it is determined that adjustment is necessary, and the routine proceeds to step 154.

Steps S154 and S155 are
This is a process for preventing the oscillation of the adjustment. Although this processing will be described later, in the first processing, step 15
5 to step 61. Steps S61 to S63
The operation is almost the same as the operation in FIG. 11 in the operation example 1 of the fifth embodiment. In step S61, the changeover switch 21 is turned on, and the impedance Z _L of the power line is measured without including the variable inductance 7.
In calculates the setting values of X _A variable inductance 7, in step S63, sets the setting value X _A calculated variable inductance 7 of the impedance adjusting portion 2.

In step S156, a predetermined time is waited after the changeover switch 22 is opened, and after a predetermined time elapses, the process proceeds to step S156.
Return to 152. Hereinafter, the measurement again receive end voltage V _S in step S152, but measurements to initiate communication with the process ends if higher than the threshold value, A low, readjustment step S154 following impedance is performed .

When the number of times of the readjustment, that is, the number of times of the counter reaches a certain value, it is determined that the oscillation of the adjustment has occurred.
The process exits from step 155 and starts communication forcibly.
Therefore, the counter is incremented in step S154, and it is determined in step S155 whether the value of the counter has reached a certain value. (Operation Example 2) The operations shown in FIGS. 16 and 17 show the operation of preventing the oscillation of the adjustment based on the difference between the previous measurement and the current measurement of the transmission / reception end voltage V _S as a criterion.

At steps 161 and 162, the counters 1 and 2 in the CPU 23 are cleared. Step 16
At 3, the transmission / reception end voltage V _S is measured using the voltage measuring device 10 with the changeover switch 21 turned off and the variable inductance 7 enabled. In step 164, a difference ΔV _S from the previous measurement is obtained.

Steps S165 to S168 are processes for determining whether or not the adjustment of the impedance has reached saturation. Although details of this processing will be described later, in the case of the first processing, the process proceeds from step S165 to step S169. Steps 169 and 170 are processes for exiting the loop by judging that oscillation of adjustment has occurred when a series of adjustment work is performed a fixed number of times or more. Although details of this processing will be described later, in the case of the first processing, the process proceeds from step S130 to step S61.

Steps 61 to 63 are the same as those in FIG. After setting the adjustment impedance Z _A by the processing of step S63, the CPU 23 waits for a certain time in step S171, and thereafter, in step 163.
Return to Thereafter, the transmission / reception end voltage V _S is measured again after step S163, and the difference ΔV _{S from the} previous time is obtained.

In steps S165 to S168, it is determined whether or not the impedance adjustment has reached saturation. In step S165, the difference ΔV _S is compared with the threshold value stored in the storage unit 24. Here, the difference [Delta] V _S increments the counter 1 in the step S166 is smaller than the threshold value. When the adjustment is saturated, the difference ΔV _S becomes smaller,
When the counter 1 reaches a certain number of times continuously, it is considered that the adjustment is saturated in step 167, and the process is terminated and communication is started.

On the other hand, if it is determined in step S165 that the difference ΔV _S is larger than the threshold value, the adjustment is not saturated, so the counter 1 is cleared in step S168, and the flow advances to step S169. Step S169, 170
Is used to determine the presence or absence of adjustment oscillation. In step S169, the number of adjustments of the variable impedance 7 is counted by the counter 2. When the number of times of the counter 2 reaches a certain value, it is determined that the adjustment oscillation has occurred, and
Exit from 0 and forcibly start communication.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a conventional power line communication device (part 1).

FIG. 2 is a diagram illustrating a circuit configuration of a conventional power line communication device (part 2).

FIG. 3 is a diagram showing a basic configuration of a power line communication device of the present invention.

FIG. 4 is a diagram showing a configuration of a system to which the power line communication device of the present invention is applied.

FIG. 5 is a diagram showing a circuit configuration according to the first embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of the circuit in FIG. 5;

FIG. 7 is a diagram illustrating a circuit configuration according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a circuit configuration according to a third embodiment of the present invention.

FIG. 9 is a flowchart showing the operation of the fourth embodiment of the present invention.

FIG. 10 is a diagram illustrating a circuit configuration according to a fifth embodiment of the present invention.

11 is a flowchart for explaining an operation example 1 of the circuit in FIG. 10;

FIG. 12 is a flowchart (part 1) for describing an operation example 2 of the circuit in FIG. 10;

FIG. 13 is a flowchart (part 2) for describing an operation example 2 of the circuit in FIG. 10;

FIG. 14 is a diagram showing a circuit configuration according to a sixth embodiment of the present invention.

FIG. 15 is a flowchart illustrating an operation example 1 of the circuit in FIG. 14;

16 is a flowchart (part 1) for describing an operation example 2 of the circuit in FIG. 14;

FIG. 17 is a flowchart (part 2) for describing an operation example 2 of the circuit in FIG. 14;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 100 ... Communication apparatus 102 ... Impedance change means 103 ... Impedance measurement means 104 ... Impedance adjustment means 1 ... Carrier generation part 2 ... Impedance adjustment part 3 ... Measurement circuit part 4 ... Calculation part 7 ... Variable inductance 10, 11 ... Voltage measurement part 12 ... Phase comparator 13 ... Absolute value calculator 14 ... Reactance component calculator 15 ... Storage unit 16 ... Variable inductance first set value calculator 17 ... Resistance component calculator 18 ... Variable inductance second set value calculator 21 Reference numeral 22: Carrier modulation unit 23: CPU 24: Storage unit 25: Storage unit a: Transmission / reception end E _M : Impedance measurement signal source E _T : Transmitter signal source L: Light line R: Receiver R _ST : Reference resistance T impedance of ... transmitter TR ... transceiver V _S ... receive end voltage X _a ... variable inductance Z ₀ ... communicator Scan Z _L ... impedance of the output impedance Z _T ... transmitter power line impedance Z _R ... impedance Z _M ... impedance measuring signal source receiver

Claims (5)

[Claims] 1. A power line communication device that uses a power line as a signal transmission path, an impedance measuring unit that measures an impedance of the power line, an impedance changing unit that changes an impedance of the power line, and the impedance measuring unit. And an impedance adjusting means for controlling the impedance changing means such that the transmission / reception end voltage becomes a predetermined value based on the impedance measured by the power line communication communication apparatus. 2. The power line communication device according to claim 1, wherein said impedance adjusting means controls said impedance changing means immediately before transmitting a signal. 3. The power line communication device according to claim 1, wherein said impedance adjusting means controls said impedance changing means at predetermined time intervals. 4. The power line communication device according to claim 1, wherein the impedance adjusting unit stops controlling the impedance changing unit when the measured impedance is equal to or more than a predetermined value. 5. A transmission / reception end voltage measurement means for measuring a transmission / reception end voltage, wherein said impedance adjustment means is provided when said transmission / reception end voltage measured by said transmission / reception end voltage measurement means is a predetermined value or more. The power line communication device according to claim 1, wherein the control of the power line communication is stopped.