WO2007063618A1

WO2007063618A1 - Signal coupler for power line carrier communication

Info

Publication number: WO2007063618A1
Application number: PCT/JP2006/312039
Authority: WO
Inventors: Yuichiro Murata; Junichi Abe; Takao Tsurimoto
Original assignee: Mitsubishi Electric Corporation
Priority date: 2005-11-29
Filing date: 2006-06-15
Publication date: 2007-06-07
Also published as: JPWO2007063618A1; JP4668279B2

Abstract

[PROBLEMS] To provide a signal coupler for power line carrier communication in which coupling efficiency can be increased in high frequency region and surge voltage can be reduced sufficiently. [MEANS FOR SOLVING PROBLEMS] A signal coupler for power line carrier communication employed in power line carrier communication for communicating a high frequency signal using a power line (8) as a transmission line and injecting a high frequency signal into the power line (8) or taking out a high frequency signal from the power line (8) comprises a capacitor (1) of high breakdown voltage connected with the power line, a drain coil (2) connected in series with the capacitor (1) of high breakdown voltage to form a series resonance circuit, and a parallel capacitor (3) connected in parallel with the drain coil (2) to form a parallel resonance circuit.

Description

Specification

Signal coupling device for power line carrier communication

Technical field

TECHNICAL FIELD [0001] The present invention relates to a signal coupling device for use in power line carrier communication that performs high-frequency signal communication using a power line as a transmission line.

Background art

[0002] A power line communication (hereinafter referred to as PLC: PLC = Power Line Communication) system performs high-frequency signal communication such as data communication by superimposing a transmission signal of 2MHz to 40MHz on a power line. In the PLC system, the signal coupling device that injects and extracts the transmission signal from the power line is composed of a capacitive coupler (hereinafter referred to as CCU: CCU = Capacitive Coupling Unit) using a high voltage capacitor. Patent Document 1 shows the configuration of a CCU. In Patent Document 1, the CCU 100 cuts off the high voltage of the power line by the high voltage capacitor 110 and the drain coil 114, which are mounted between the terminal 102 to which the power line is attached and the terminal 106 for grounding, and the matching transformer 202 The high-frequency signal is taken out to the communication modem through the matching circuit 201 configured by the capacitor 204 provided in the secondary circuit.

Patent Literature l: US2001 / 0038329 (paragraphs 0050, 0051,0055 and FIG.1, 2)

Disclosure of the invention

Problems to be solved by the invention

[0003] The characteristic impedance of the power line is 50 Ω to 400 Ω, whereas the characteristic impedance of the communication modem input / output section is 50 Ω. For this reason, a circuit that performs impedance matching is provided inside the CCU. For the impedance matching circuit, a matching transformer with different number ratios on the primary and secondary sides is used. However, with the matching transformer alone, the output voltage drops in the high frequency region above 10 MHz. Hereinafter, the ratio of the input voltage from the overhead line to the signal coupling device and the output voltage from the signal coupling device to the communication modem is called coupling efficiency.

[0004] In addition, in an arrester used as a surge voltage protection element, the power line is There was a problem that surge voltage could not be absorbed.

[0005] The present invention has been made to solve the above-described problems, and it is possible to increase the coupling efficiency in the high-frequency region and sufficiently reduce the surge voltage. Is to provide.

Means for solving the problem

[0006] The present invention is used in power line carrier communication that performs high-frequency signal communication using a power line as a transmission line. In a power line carrier communication signal coupling device that injects and extracts a high-frequency signal from a power line, the power line is connected to a power line. A withstand voltage capacitor, a drain coil connected in series to the high withstand voltage capacitor and forming a series resonance circuit, and a parallel 1J capacitor connected in parallel to the drain coil and forming a parallel resonance circuit .

The invention's effect

According to the signal coupling device for power line carrier communication of the present invention, there is an effect that the capacitor provided in parallel with the drain coil can increase the coupling efficiency in the high frequency region and sufficiently reduce the surge voltage.

Brief Description of Drawings

FIG. 1 is a circuit configuration diagram of a signal coupling device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing the relationship between the capacitance of a parallel capacitor and the coupling efficiency according to Embodiment 1 of the present invention.

FIG. 3 is a characteristic diagram showing characteristics of the arrester according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a winding line of a matching transformer according to Embodiment 2 of the present invention. Explanation of symbols

[0009] 1 high voltage capacitor, 2 drain coil, 3 parallel capacitor, 4 protection element, 5 matching transformer, 6 protection element, 7 connector, 21 magnetic core, 51 magnetic core

52 High resistance or inductance

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Embodiment 1.

FIG. 1 shows a circuit of a signal coupling device 100 for power line carrier communication according to Embodiment 1 of the present invention. It is a figure which shows a structure. In FIG. 1, 1 is a high voltage capacitor connected to the power line 8, 2 is a drain coil connected in series with the high voltage capacitor 1, and the magnetic core 21 is coiled and configured.

3 is a parallel capacitor connected in parallel to the drain coil 2, and 5 is a matching transformer connected in parallel to the parallel capacitor 3. The magnetic core 51 is configured with a primary winding W 1 and a secondary winding W 2. Has been. Protection elements 4 and 6 such as surge arresters are provided on the primary and secondary sides of the matching transformer 5. Reference numeral 7 denotes a connector as an input / output terminal, which is connected to a communication modem (not shown) via a cape nore.

Next, the operation will be described. The high voltage capacitor 1 and the drain coil 2 shown in Fig. 1 form a series resonance circuit, and the drain coil 2 and the parallel capacitor 3 form a parallel resonance circuit. The series resonance frequency fl is determined by the capacitance C1 of the high voltage capacitor 1 and the inductance L of the drain coil 2, and the parallel resonance frequency ί2 is determined by the capacitance C2 of the parallel capacitor 3 and the inductance L of the drain coil 2. Each resonance frequency is given by the following equation.

[0012] [Equation 1]

2TTJLC1

[0013] Figure 2 shows the calculation results of the coupling efficiency when the capacitance of the parallel capacitor 3 is changed to 0, 100, 200, 500, and 1000 Pf. When there is no parallel capacitor 3 (OpF), there is only a series resonant circuit, so there is only one resonant frequency, and the coupling efficiency shows a maximum at only one location (in the example shown in Fig. 2, 6MHz ). By providing parallel capacitor 3, maximum values are shown at two locations, the direct resonance frequency and the parallel resonance frequency. By adjusting the two resonance frequencies, the high frequency characteristics of the coupling efficiency can be increased. That is, by setting the parallel resonance frequency f2 higher than the series resonance frequency η, the high frequency characteristics of the signal coupling device can be increased. That is, the condition of C1> C2 should be satisfied. FIG. 3 shows the characteristics of the gas arrester used as the protective elements 4 and 6. It is a figure which shows an applied voltage waveform when arresting a pulse voltage in an arrester, and an arrester both-ends voltage waveform. As shown in Fig. 3 (a), when a pulse voltage with a rise time of several s is obtained, if the voltage applied to the arrester exceeds the arrester operating voltage, the arrester operates, the voltage across the arrester becomes 0 V, and the power line Protects other elements against surge voltage from. As shown in Fig. 3 (b), when a pulse voltage with a rise time of several ns is applied, the arrester will not operate until the arrester operating delay time T1 is reached even if the arrester applied voltage exceeds the arrester operating voltage. Les. In this case, a voltage higher than the arrester operating voltage is applied to the other elements, and the other elements cannot be protected.

[0015] Thus, it is impossible to protect a high-speed surge voltage having a short rise time from the power line using only a nonlinear element. In this case, a capacitor 3 is provided in parallel with the drain coil 2, and this parallel capacitor 3 can absorb high-speed surge voltage and protect other elements. By using a parallel capacitor 3 with a capacitance of 10pF to 500pF, the pulse voltage with a rise time of several ns can be sufficiently reduced.

[0016] As the protective elements 4 and 6, non-linear elements are used in which the protective element operates when a certain voltage is reached and the voltage at both ends is 0V. As such a protective element, a surge arrester, a gas gap arrester, a gas arrester, a noristor, a diode, or the like is used. Any one element can be used, and V, G, and G can be combined.

As described above, according to the first embodiment, the power line carrier is used for power line carrier communication that performs high-frequency signal communication using the power line 8 as a transmission line, and injects and extracts high-frequency signals from the power line 8. In a signal coupling device for communication, a high voltage capacitor 1 connected to a power line, a drain coil 2 connected in series to the high voltage capacitor 1 and forming a series resonance circuit, and a parallel connection to the drain coil 2 and parallel resonance By providing the parallel capacitor 3 forming the circuit, the coupling efficiency in the high frequency region can be increased and the surge voltage can be sufficiently reduced.

[0018] In addition, by making the series resonance frequency determined by the high voltage capacitor 1 and the drain coil 2 lower than the parallel resonance frequency determined by the drain coil 2 and the parallel capacitor 3, the coupling efficiency shows maximum values at two frequencies. And adjust the capacitance of the capacitor Thus, a signal coupling device having high coupling efficiency in a wide frequency range can be obtained.

Furthermore, by making the capacitance of the high voltage capacitor 1 larger than the capacitance of the parallel capacitor 3, the series resonance frequency can be set lower than the parallel resonance frequency, and by adjusting the capacitance of the parallel capacitor 3, a wide range can be obtained. It is possible to obtain a signal coupling device having high coupling efficiency in the frequency range.

[0020] As the parallel capacitor 3, a capacitor element such as a ceramic capacitor or an electric field capacitor may be used, or a stray capacitance between a substrate pattern or a coiled wire may be used. Further, a capacitance component may be built in the substrate.

In order to improve the communication speed, it is necessary to increase the frequency band of the signal. For this reason, a flat signal coupling device is required at a frequency with high frequency characteristics of coupling efficiency.

. However, pulsating noise such as lightning and open / close surge of disconnecting device is generated on the power line. If this noise is transmitted to the communication device via the signal coupling device, the input portion of the communication device is damaged. For this reason, it is necessary to consciously cut high-frequency coupling efficiency. For example, it is necessary to rapidly reduce the coupling efficiency at a frequency of 40 MHz or higher. Even in such a case, the first embodiment is effective.

Embodiment 2.

In the first embodiment, it has been shown that the high-speed surge voltage with a rise time of several ns can be sufficiently reduced by the capacitor 3 provided in parallel with the drain coil 2. In order to prevent the reduced surge voltage from being transmitted to the communication modem, it is necessary that the insulation withstand voltage between the primary side and the secondary side of the matching transformer 5 be sufficiently high. By satisfying the specified dielectric strength voltage, the insulation between the power line and the communication modem is guaranteed regardless of the type and installation state of the cable connecting the signal coupling device and the communication modem, and a safe signal coupling device is provided. Deliver power S.

[0022] In order to evaluate the insulation withstand voltage of matching transformer 5, a high voltage is applied to primary side wire W1, and the voltage at which the insulation on the secondary side and the primary side breaks (breakdown voltage) is measured. To do. If the breakdown voltage is sufficiently high, the insulation withstand voltage of the matching transformer 5 is guaranteed. If the breakdown voltage is 5kV or more, the connector 7 has 5kV or more. It does not generate voltage. In addition, the input terminal of the communication modem is designed to withstand pulse noise of 5kV for ESD (Electro Static Discharge) protection. Therefore, the insulation withstand voltage of the matching transformer 5 must be 5kV (breakdown voltage) on the secondary and primary sides.

[0023] As a method for achieving such an insulation withstand voltage, a material having a high specific resistance such as NiZn ferrite is used as the magnetic core 51 used in the matching transformer 5 as shown in FIG. 4 (a). Force S is needed. In addition, the predetermined insulation withstand voltage is achieved by making the primary winding W1 and the secondary winding W2 face each other or using a coated copper wire. Also, connect the primary and secondary ground terminals of the matching transformer 5 to each other, or connect them through high resistance or inductance 52 as shown in Fig. 4 (b). Can be achieved.

[0024] Further, the magnetic saturation of the magnetic core 51 can be utilized to reduce the high voltage magnetic saturation.

As described above, according to the second embodiment, the matching transformer is connected in parallel with the parallel capacitor 3.

In addition to connecting 5 and setting the insulation withstand voltage on the primary and secondary sides of the matching transformer 5 to 5 kV or higher, the high-frequency surge voltage can be used regardless of the type and condition of the cable connecting the signal coupling device and the communication modem. Can be sufficiently attenuated.

Claims

The scope of the claims

[1] In a power line carrier communication signal coupling device that is used for power line carrier communication that performs high frequency signal communication using a power line as a transmission line, and that injects and extracts the high frequency signal from the power line.

A high-voltage capacitor connected to the power line; a drain coil connected in series to the high-voltage capacitor to form a series resonance circuit; and a parallel capacitor connected in parallel to the drain coil to form a parallel resonance circuit. A power line carrier communication signal coupling device characterized by that.

2. The signal coupling device for power line carrier communication according to claim 1, wherein a series resonance frequency determined by the high voltage capacitor and the drain coil is lower than a parallel resonance frequency determined by the drain coil and the parallel capacitor. .

[3] The signal coupling device for power line carrier communication according to [1], wherein a capacity of the high voltage capacitor is larger than a capacity of the parallel capacitor.

[4] The power line carrier communication according to claim 1, wherein a matching transformer is connected in parallel with the parallel capacitor, and a dielectric strength voltage of the primary side and the secondary side of the matching transformer is set to 5 kV or more. Signal coupling device.