JP2006229774A - Filter circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter circuit in which the magnitude of the inductance of a conductive wire can be made small by thinning the conductive wire used in the filter circuit, a signal attenuation ratio of power line communication or a noise elimination ratio of high frequency electromagnetic noise can be determined by difference in impedance between a bypass circuit and a main circuit, and the conductor of the main circuit is made small. <P>SOLUTION: The filter circuit is arranged in a transmission path of power line communication that superimposes a signal of a frequency different from a commercial power frequency on the commercial power frequency to perform communication, and the filter circuit is used to interrupt both a signal of the power line communication and electromagnetic noise included in the commercial power frequency, and the filter circuit has the main circuit for making only a commercial power current having the commercial power frequency pass through without interrupting the commercial power current, and the bypass circuit for interrupting only the signal of the power line communication and the electromagnetic noise. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a filter circuit for preventing unintended leakage of a signal on a transmission line and removing high-frequency electromagnetic noise propagating on a commercial power line in power line carrier communication.

  In power line communication, a power line communication signal transmitted on a commercial power line in a building is unintentionally leaked to another power line that is drawn from the outside of the building and connected to the commercial power line. Signal leakage prevention is very important in order to prevent leakage from commercial power lines as electromagnetic noise and to ensure the security of power line carrier communications and to eliminate the influence on the electromagnetic environment.

  On the other hand, in many electric / electronic devices such as home appliances, an inverter control type power source is adopted for the purpose of power saving, and high frequency electromagnetic noise having various frequency components propagates on a commercial power line. This high-frequency electromagnetic noise has a problem that it adversely affects the operation of the device and interferes with broadcast reception.

  In order to prevent such signal leakage and the influence of high-frequency electromagnetic noise, a filter for a commercial power line is used.

  A conventional commercial power supply line filter uses a method of inserting a low-pass filter, a high-pass filter, or the like into the power supply line. These filters are, for example, an LC resonance circuit composed of an inductor (L) on a power line conductor and a capacitor (C) between the conductors, as seen in a low-pass filter for power line communication and a blocking filter, and in-phase components of signals. It is comprised by the common mode choke inductor etc. which remove (refer patent document 1).

  FIG. 10 is a configuration example of a circuit for the purpose of preventing signal leakage or removing high-frequency electromagnetic noise for both the line-to-line and in-phase components of the conventional filter circuit. An inductor L100, a capacitor C101, and a common mode choke inductor CMC102 are included. With this configuration, both common mode noise and normal mode noise are filtered.

  FIG. 11 is a configuration example of a circuit for the purpose of preventing signal leakage or removing high-frequency noise in a signal transmission system using one conductor and a ground plane among conventional filter circuits. A plurality of inductors L103 and a capacitor C104 are included.

FIG. 12 is a further development of the conventional filter circuit shown in FIG. 11, and is a configuration example of a circuit for the purpose of preventing signal leakage between lines or removing high-frequency electromagnetic noise. A plurality of inductors L103 and a capacitor C104 are included.
Japanese Patent Laid-Open No. 5-121988

  In the above-described conventional technology, not only the power line carrier communication signal or high-frequency electromagnetic noise but also the current of the commercial power supply is transmitted on the circuit constituting the filter. For this reason, even when leakage prevention is intended only for power line carrier communication signals or high frequency electromagnetic noise, it is necessary to configure a circuit in consideration of the current capacity of the commercial power source.

  In addition, the allowable current value of the power supply line is determined by its thickness, and in the case of a copper wire, the allowable current capacity is 61 A at a thickness of about 4 mm. At present, even in ordinary households, the current rating capacity of the contract breaker may be 60A, and an inductor or common mode choke inductor is configured using a copper wire with a thickness of about 4mm to load a sufficiently large impedance on the commercial power line. As a result, the physical occupied volume of the elements constituting these impedances is increased.

  In addition, since the elements constituting the filter are increased in size as described above, it is unavoidable that the filter itself is increased in size.

  Also, a magnetic core such as iron is used to configure a large value inductor or common mode choke inductor in a limited space. However, when a large current flows through the magnetic core, the inductance decreases due to magnetic saturation. However, the impedance of the inductor is lowered at high frequency due to stray capacitance between the magnetic core and the inductor due to the resonance frequency shift and the deterioration of the common-mode signal removal effect, and the thick conductor is wound. It becomes difficult to improve the characteristics.

The present invention has been made in view of the above problems, and the object of the present invention is to reduce the size of the inductor by thinning the conducting wire used in the filter circuit,
It is another object of the present invention to provide a filter circuit in which the signal attenuation ratio of power line carrier communication or the high frequency electromagnetic noise elimination ratio can be determined by the difference in impedance between the bypass circuit and the main circuit, and the inductor of the main circuit is made small.

  In order to solve the problem, the present invention according to claim 1 is arranged in a transmission line of power line carrier communication that performs communication by superimposing a signal having a frequency different from a commercial power source frequency on the commercial power source frequency, and the power line carrier. A filter circuit for blocking both a communication signal and electromagnetic noise included in the commercial power frequency, and a main circuit for allowing only a commercial power current having the commercial power frequency to pass through without being blocked And a bypass circuit for cutting off only the signal of the power line carrier communication and the electromagnetic noise.

  According to a second aspect of the present invention, in the first aspect, the bypass circuit is set such that an impedance in a frequency band higher than the commercial power supply frequency is lower than an impedance in the frequency band of the main circuit.

  Further, according to a third aspect of the present invention, the bypass circuit and the main circuit according to any one of the first and second aspects are each predetermined by a combination of both or one of an inductor and a resistor. Impedance characteristics are set.

  According to a fourth aspect of the present invention, in the third aspect, the impedance characteristic is a leakage prevention ratio of the power line carrier communication signal set in any frequency band of the power line carrier communication or the high frequency electromagnetic noise. Alternatively, it is determined based on one of the high-frequency electromagnetic noise removal ratios.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the bypass circuit has a capacitor disposed between opposing conductors in the transmission path.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the bypass circuit includes a capacitor disposed between a potential midpoint between opposing conductors in the transmission path and the ground. Has been.

  According to a seventh aspect of the present invention, in any one of the fifth or sixth aspects, the capacitor is formed of an overvoltage protection element having an equivalent capacitance.

  According to an eighth aspect of the present invention, in any one of the third to sixth aspects, an overvoltage protection element is connected in parallel to the capacitor or the resistor.

  In the present invention according to claim 9, the power capacity of the inductor, the resistor, and the capacitor is set with a predetermined margin with respect to the commercial power supply current.

According to the present invention, the size of the inductor can be reduced by thinning the conducting wire used in the filter circuit,
In addition, the signal attenuation ratio of the power line carrier communication or the high frequency electromagnetic noise rejection ratio can be determined by the difference in impedance between the bypass circuit and the main circuit, and a filter circuit with a small inductor in the main circuit can be provided.

<Basic configuration of the present invention>
FIG. 1 is an explanatory diagram for explaining a basic configuration according to an embodiment of a filter circuit of the present invention.

FIG. 1 shows a transmission line 3 of a commercial power supply schematically represented, a main circuit 2 having an impedance Z _m 5, and a bypass circuit 1 having an impedance Z _b 4. In such a basic configuration, an alternating current with a frequency of 50 Hz or 60 Hz, for example, as the commercial power supply frequency is conducted through the transmission line 3 of the commercial power supply.

  In addition, a signal for power line carrier communication is superimposed on the commercial power frequency in the transmission path 3 and is conducted. Communication is performed via a power line transmission line 3 such as a commercial power source by this power line carrier communication. The frequency band used in the power line carrier communication is assigned a high frequency band such as 1 to 30 MHz as compared with the commercial power supply frequency.

  When connecting to a commercial power source for power supply to a device not shown in the figure, this communication signal is used when the device does not support power line carrier communication and rather does not require a power line carrier communication signal. Leakage to other equipment becomes a problem. In addition to the necessity of concealing the contents of communication, it is necessary to block in order to avoid the influence on the operation of the device. In addition to such communication signals, electromagnetic noise mixed in the commercial power supply must be blocked so as not to affect the device.

  Therefore, in the embodiment of the present invention, AC power having a commercial power supply frequency is conducted to the main circuit 2. At the same time, the bypass circuit 1 is made to conduct the communication signal of the power line carrier communication described above or electromagnetic noise.

Here, referring to FIG. 2, impedance Z _m 5 of main circuit 2 is set so that the impedance value is low in the frequency band of the commercial power supply frequency (for example, 50 Hz or 60 Hz). Further, the impedance Z _b 4 of the bypass circuit 1 is set so that the impedance value becomes low in the frequency band (for example, 1 to 30 MHz) of the communication signal of the power line carrier communication. As shown in FIG. 2, there is a relationship of Z _b (f) <Z _m (f), where f is a frequency band (for example, 1 to 30 MHz) higher than the commercial power supply frequency.

  Next, FIG. 3 shows an example in which the basic configuration of the embodiment of the present invention shown in FIGS. 1 and 2 is further embodied and modified. In FIG. 3, the conductor corresponding to the transmission line 3 shown in FIGS. 1 and 2 is a conductor composed of a pair of opposing conductors connected to the terminals a10 to c12 and conductors connected to the terminals b11 to d13. It is.

Further, to constitute the bypass circuit 1 and two inductors L _{1 6,} a capacitor C9. A combination of these inductor L ₁ 6 and capacitor C9 forms a time constant circuit, and impedance Z _b 4 of bypass circuit 1 is set.

Capacitor C9 is provided to prevent leakage of power line carrier communication signals or electromagnetic noise transmitted between opposing conductors. The inductor L ₂ 7 and the resistor R8 are arranged to generate the impedance Z _m 5 of the main circuit 2.

  Next, FIG. 4 shows another example in which the basic configuration of the embodiment of the present invention shown in FIGS. In this configuration, two capacitors C9 shown in FIG. 3 are provided, and one end of each capacitor C9 is grounded to the ground 14 together.

  With such a configuration, it is possible to prevent leakage of the in-phase component of the power line carrier communication signal and high-frequency electromagnetic noise transmitted between the midpoint of the potential between the opposing conductors and the ground (ground) 14.

<First Embodiment>
FIG. 5 is an equivalent circuit diagram of the filter circuit according to the first embodiment of the present invention. This is because the ratio between the input impedance of the main circuit (Z _m 5 shown in FIG. 1) and the input impedance of the bypass circuit (Z _b 4 shown in FIG. 1) is almost 100: 1, and the power line between the lines has a frequency of 1 to 30 MHz. The values of the inductors L ₁ 6 and L ₂ 7, the capacitor C 9, and the resistor R 8 are determined so that the signal leakage prevention of the carrier communication or the high frequency electromagnetic noise removal effect is 40 dB or more.

In FIG. 5, the value of L ₁ 6 is 10 nH, the value of L ₂ 7 is 1 μH, the value of resistor R is 0.001Ω, and the value of capacitor C 9 is 1 μF.

  In such a filter circuit, the overvoltage resistance performance of the filter circuit can be improved by replacing the capacitor C9 with an overvoltage protection element such as a varistor having a capacitance equivalent to that of the capacitor.

  FIG. 6 shows the ratio of the input voltage between the terminals a10 and b11 of the filter circuit shown in FIG. 5 and the output voltage between the terminals c12 and d13, and prevents signal leakage or high-frequency electromagnetic noise removal in the power line communication of the filter circuit. It shows the effect. It is shown that the input voltage is attenuated by 40 dB or more and output at a frequency of 1 to 30 MHz.

<Second Embodiment>
FIG. 7 is an equivalent circuit diagram of the filter circuit according to the second embodiment of the present invention. This is because the ratio of the input impedance of the main circuit to the input impedance of the bypass circuit is almost 100: 1, and the signal leakage prevention or high-frequency electromagnetic noise removal effect of power line carrier communication between lines with a frequency of 1 to 30 MHz is 40 dB or more. Thus, the values of the inductors L ₁ 6 and L ₂ 7, the capacitor C 9, and the resistor R 8 are determined.

In FIG. 7, the value of _{L 1} 6 and 100 nH, the value of _{L 2} 7 and 10 .mu.H, the value of the resistor R and 0.001 ohm, is set to 1μF value capacitor C9.

  In such a filter circuit, the overvoltage resistance performance of the filter circuit can be improved by replacing the capacitor C9 with an overvoltage protection element such as a varistor having a capacitance equivalent to that of the capacitor.

  FIG. 8 shows the frequency characteristics of the current flowing through the bypass circuit and the main circuit for each of the filter circuit according to the first embodiment and the filter circuit according to the second embodiment.

  In any of the circuits, the main circuit transmits the current of the commercial power supply frequency but does not transmit the current of the frequency 1 to 30 MHz. The bypass circuit does not transmit the current of the commercial power supply frequency but transmits the current of the frequency 1 to 30 MHz. Yes.

  In this way, by fixing the ratio of the input impedance of the bypass circuit and the main circuit, and determining the values of the inductor, capacitor, and resistance that constitute the bypass circuit and the main circuit so as to satisfy it, the signal of the equivalent power line carrier communication It can be seen that leakage prevention or high-frequency electromagnetic noise removal effects can be obtained.

  Therefore, in the conventional circuit configuration, an inductor of μH order or more is required. In the present invention, if the ratio of the input impedance of the main circuit and the bypass circuit is the same, the value of the inductor of the circuit is set to nH order. can do. As a result, the size of the inductor can be reduced, and a small filter circuit can be configured.

  In FIG. 8, the thin solid line 20 indicates the frequency cutoff characteristic of the main circuit according to the first embodiment, and the solid solid line 22 indicates the frequency cutoff characteristic of the bypass circuit according to the first embodiment. Similarly, the dotted line 21 indicates the frequency cutoff characteristic of the main circuit of the second embodiment, and the thick solid line 23 indicates the frequency cutoff characteristic of the bypass circuit of the second embodiment.

  FIG. 9 shows the specification of a commercial power supply filter circuit having a current capacity of 60 A applied to the circuit having the configuration shown in the embodiment of the present invention and the filter circuit (a and b in the figure) referred to in the prior art. This is a comparison with the circuit. A circuit having the same level of signal leakage prevention effect and the same current capacity can be realized with a volume about one-tenth that of the prior art.

  According to the embodiment of the present invention described above, a bypass circuit configured by using an inductor, a resistor, or a combination of an inductor and a resistor, a current of a commercial power source and a power line carrier communication signal or high-frequency electromagnetic noise to be prevented from leaking. The signal attenuation ratio or high-frequency electromagnetic noise elimination ratio of power line carrier communication is determined by the impedance difference between the bypass circuit and the main circuit. A featured filter circuit can be constructed.

  In addition, the power line carrier communication signal or high-frequency electromagnetic noise that you want to prevent from leaking is transmitted to the bypass circuit, and the current of the commercial power supply is transmitted to the main circuit, so that the conductor used in the bypass circuit is narrowed and the size of the inductor is reduced. As a result, a small filter circuit can be configured.

  Furthermore, the signal attenuation ratio of the power line carrier communication or the high frequency electromagnetic noise rejection ratio can be determined by the impedance difference between the bypass circuit and the main circuit at the frequency of the commercial power supply and the frequency of the power line carrier communication or the high frequency electromagnetic noise. The impedance on the transmission line of the circuit can be reduced as compared with a conventional line-to-line or common mode filter. As a result, the value of the inductor of the main circuit is reduced, and the size of the main circuit can be reduced.

  That is, with respect to the bypass circuit, since only a small current such as a power line carrier communication signal or high-frequency electromagnetic noise flows, the conducting wire can be made thin, and the inductors and resistors constituting the circuit can be miniaturized.

  Further, since the impedance on the transmission line of the main circuit is small, the power factor does not deteriorate, and there are effects of energy saving and low heat generation.

The explanatory view for explaining the basic composition concerning the embodiment of the filter circuit of the present invention is shown. The explanatory view for explaining the basic composition concerning the embodiment of the filter circuit of the present invention is shown. The explanatory view for explaining the basic composition concerning the embodiment of the filter circuit of the present invention is shown. The explanatory view for explaining the basic composition concerning the embodiment of the filter circuit of the present invention is shown. The equivalent circuit diagram for demonstrating the structure based on 1st Embodiment of the filter circuit of this invention is shown. The characteristic view for demonstrating the filter characteristic based on 1st Embodiment of the filter circuit of this invention is shown. The equivalent circuit diagram for demonstrating the structure based on 2nd Embodiment of the filter circuit of this invention is shown. The characteristic view for demonstrating the filter characteristic based on 1st and 2nd embodiment of the filter circuit of this invention is shown. The comparison figure for demonstrating the comparison of the physical magnitude | size of the filter circuit of this invention and the filter circuit by a prior art is shown. The equivalent circuit diagram for demonstrating the filter circuit by a prior art is shown. The equivalent circuit diagram for demonstrating the filter circuit by a prior art is shown. The equivalent circuit diagram for demonstrating the filter circuit by a prior art is shown.

Explanation of symbols

1 Bypass circuit 2 Main circuit 3 Transmission path 4 Impedance Z _b
5 Impedance Z _m
6 Inductor L ₁
7 Inductor L ₂
8 Resistance R
9 Capacitor C

Claims (9)

A power line carrier communication signal for performing communication by superimposing a signal having a frequency different from the commercial power source frequency on the commercial power source frequency, and the power line carrier communication signal and electromagnetic noise included in the commercial power source frequency, A filter circuit for blocking both,
A main circuit for allowing only the commercial power source current having the commercial power frequency to pass without being cut off;
A bypass circuit for blocking only the power line carrier communication signal and the electromagnetic noise;
A filter circuit comprising: The bypass circuit is:
The filter circuit according to claim 1, wherein an impedance in a frequency band higher than the commercial power supply frequency is set lower than an impedance in the frequency band of the main circuit. The bypass circuit and the main circuit are:
3. The filter circuit according to claim 1, wherein predetermined impedance characteristics are set by both or either one of an inductor and a resistor. 4. The impedance characteristic is
It is determined based on either the leakage prevention ratio of the power line carrier communication signal set in the frequency band of either the power line carrier communication or the high frequency electromagnetic noise or the removal ratio of the high frequency electromagnetic noise. The filter circuit according to claim 3. The bypass circuit is:
The filter circuit according to claim 1, wherein a capacitor is disposed between opposing conductors in the transmission path. The bypass circuit is:
The filter circuit according to claim 1, wherein a capacitor is disposed between a potential midpoint between opposing conductors in the transmission line and the ground. The capacitor is
The filter circuit according to claim 5, wherein the filter circuit is configured by an overvoltage protection element having an equivalent capacitance. The capacitor or the resistor is
The filter circuit according to claim 3, wherein overvoltage protection elements are connected in parallel. For the commercial power supply current,
The filter circuit according to claim 3, wherein power capacities of the inductor, the resistor, and the capacitor are set with a predetermined margin.

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