KR100841652B1 - A power line coupler circuit for a power line communication - Google Patents

Abstract

A power line coupler circuit for a PLC is provided to use a small core by increasing composition inductance by a negative inductor circuit unit and to reduce a size of a power line transceiver. A power line coupler circuit for a PLC(Power Line Communication) comprises a coupling transformer(1) and an inductor converter(2). The inductor transformer minimizes leakage inductance by minimizing the number of winding turns of the coupling transformer by increasing composition inductance with a magnetization inductance of the coupling transformer. In order to increase a pass band width of a PLC by increasing a high band cut off frequency among pass band widths of the PLC, the inductor converter has negative inductance connected between a PL modem and the coupling transformer.

Description

Power line combiner circuit for power line communication {A POWER LINE COUPLER CIRCUIT FOR A POWER LINE COMMUNICATION}

1 is a schematic circuit diagram showing a configuration of a power line combiner circuit for power line communication according to the prior art;

2 is a signal attenuation and frequency characteristic diagram of a power line coupler circuit for power line communication according to the prior art which acts as a bandpass filter.

3 is a schematic circuit diagram showing the configuration of a power line coupler circuit for power line communication according to the present invention;

4 is a circuit diagram showing a detailed circuit configuration of the negative inductor circuit portion of the power line coupler circuit for power line communication according to the present invention,

5 is a circuit diagram showing in more detail the configuration of a power line combiner circuit for power line communication according to the present invention;

6 is a signal attenuation and frequency characteristic diagram of a power line combiner circuit for power line communication according to the present invention which acts as a bandpass filter.

* Explanation of symbols on the main parts of the drawings

1: power line coupler 1a: coupling transformer

1b: coupling capacitor 2: negative inductor circuit portion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to power line communication. In particular, in the power line coupler circuit for power line communication, the number of turns of the coupling transformer is small, but the combined inductance is increased, and parasitic components such as leakage inductance and winding resistance are reduced, so that the power line has a wide bandwidth. Relates to a coupler circuit.

Power line communication can use existing power line without additional communication line, so investment cost is low and home network and home automation can be easily connected by plugging into power socket on the wall of building. (Home Automation), Internet Information Appliances, Automatic Meter Reading (AMR), and factory automation are the most suitable communication media. However, power lines have a problem in that communication performance is degraded due to a lot of noise, attenuation, fading, etc. on the channel. In order to overcome the problems of the power line channel, a spread spectrum technique and a multi-carrier technique are used.

Since the spread spectrum technology and the multi-carrier technology require a wider communication bandwidth than the narrowband technology, the coupling transformer must also be designed to have a wide band characteristic. However, the design of transformers and couplers with wide bandwidths is very difficult due to the current characteristics of the coupling transformer and parasitic components (leakage inductance, winding resistance, etc.).

Meanwhile, referring to the attached FIGS. 1 and 2, the configuration of the power line coupler circuit for power line communication and the signal frequency bandwidth and attenuation characteristic during transmission and reception according to the prior art will be described as follows.

In FIG. 1, reference numeral 1 denotes a power line combiner for power line communication, which is connected between a power line modem and a power line PL to perform an interface function for transmitting and receiving communication signals between the power line modem and the power line PL. The power line combiner 1 includes a coupling transformer 1a and a coupling capacitor 1c.

In a receiving operation, the coupling transformer 1a and the coupling capacitor 1b act as a high pass filter to block a 60 Hz commercial AC power signal and to pass a higher frequency communication signal.

Meanwhile, FIG. 2 shows that the capacitance value of the coupling capacitor 1b is 0.22 μF in the power line coupler of FIG. 1, and that the primary winding resistance and the secondary winding resistances R _p1 and R _p2 of the coupling transformer 1a are 0.3 Ω. When the primary winding leakage inductance and secondary winding leakage inductance of the coupling transformer (1a) is 0.3 μH, the magnetizing inductance Lc is 1 mH, and the power line impedance (R _AC ) is 2 ohms, respectively. Signal characteristic diagram showing characteristic. In Fig. 2, the pass frequency band is a low frequency lower limit of 224 kHz and a high frequency upper limit of 855 kHz with attenuation of -3 dB or more. The center frequency is 438 kHz and the signal attenuation at the center frequency is -1.6 dB.

Signal Characteristics of FIG. 2 When the power line coupler of FIG. 1 according to the prior art exhibiting the same signal characteristics as in the example of FIG. do. Therefore, the capacitance of the coupling capacitor 1b should be increased to move the low cutoff frequency to a low frequency, and the leakage inductance must be reduced to move the high cutoff frequency to a high frequency.

Increasing the capacitance of the coupling capacitor 1b proportionally increases the alternating current flowing through the coupling capacitor 1b. It also flows back through the coupling transformer 1a. Therefore, it is necessary to characterize the current of the coupling transformer 1a. The inductance and AC maximum (peak) current of the coupling transformer 1a are as follows.

Inductance of the coupling transformer 1a

AC maximum current flowing through the coupling transformer 1a

Where A _L is the inductance factor of the coupling transformer 1a, N is the number of turns, A _e is the effective cross section, and B is the saturation magnetic flux density.

In equations (1) and (2) above, the inductance increases in proportion to the square of the number of turns, and the number of turns and the AC maximum current are inversely related. Therefore, in consideration of the relationship between the AC maximum current and the number of turns, in order to increase the inductance of the coupling transformer 1a, it is necessary to increase the core cross-sectional area of the coupling transformer 1a or increase the maximum saturation magnetic flux density rather than to increase the number of turns. Preference is given to using materials.

In addition to the current characteristics of the coupling transformer 1a described above, it is necessary to characterize secondary components such as leakage inductance and winding resistance. Next is the winding inductance and leakage inductance of the coupling transformer 1a.

Winding resistance

Leakage inductance

In the above equations (3) and (4), ρ is the resistance of the power line, F _W is the fill factor of the power line, A _W is the area of the power line, l _t is the average winding length, and a, b, and c are each 1 Primary winding, secondary winding and insulation layer thickness.

It can be seen from the above equations (3) and (4) that the leakage inductance (L _eak ) and the winding resistance (R _p ) of the coupling transformer (1a) increase in proportion to the square of the number of turns. However, coupling to move the leakage inductance is high-pass cut-off frequency (L _eak) of the ring transformer (1a) and a low frequency, it is necessary to reduce the number of turns due to the winding resistance (R _p) is decreased when the key signal in the pass band.

Therefore, according to the prior art, the power line combiner according to the prior art, which is connected to the spread spectrum and the multi-carrier power line modem, increases the capacity of the coupling capacitor 1b to move the low cutoff frequency to low frequency. In the power line coupler according to the related art, the coupling transformer 1a is required to have a high inductance while minimizing the number of turns in consideration of current characteristics, leakage inductance, and winding resistance.

However, the coupling transformer that satisfies these conditions has a problem that the cross-sectional area of the core is greatly increased, thereby increasing the size and price of the coupling transformer.

Accordingly, an object of the present invention is to provide a power line coupler circuit for power line communication that can maintain a high inductance and can be manufactured at low cost while maintaining a small number of turns of a coupling transformer.

An object of the present invention is to provide a power line combiner circuit for power line communication that processes signal transmission and reception between a power line and a power line modem.

A power line combiner circuit for power line communication that processes signal transmission and reception between a power line and a power line modem,

Coupling transformers; And

Negative inductance connected between the powerline modem side and the coupling transformer to increase the passband of powerline communication by increasing the high cutoff frequency of the passband of powerline communication by increasing the combined inductance with the magnetizing inductance of the coupling transformer. It can be achieved by providing a power line combiner circuit for power line communication according to the invention, characterized in that it comprises an inductor converter having a.

The object of the present invention and the constitution and effect of the present invention to achieve the same will be more clearly understood by the following detailed description of the preferred embodiment with reference to the accompanying drawings.

First, the configuration of a power line combiner circuit for power line communication according to the present invention will be described with reference to FIG.

As shown in FIG. 3, the power line combiner circuit for power line communication according to the present invention is a circuit for processing signal transmission and reception between a power line PL and a power line modem.

Inductance converters with negative inductance (-L _N ), in other words negative inductors, connected to the power line modem side in order to increase the high pass cutoff frequency of the power line communication by increasing the combined inductance, thereby increasing the high pass cutoff frequency of the power line communication. It is characterized by including a circuit part (2). Here, although the negative inductor circuit unit 2 is simply shown as one coil, an exemplary embodiment may further include an operational amplifier and resistors as shown in, for example, FIGS. 4 and 5. Reference numeral 1 in FIG. 3 denotes a power line coupler.

Meanwhile, the configuration of the negative inductor circuit unit 2 will be described in more detail with reference to FIG. 4 showing a detailed circuit configuration of the negative inductor converter circuit unit in the power line communication circuit for power line communication according to the present invention. .

The inductor converter, i.e., the negative inductor circuit section 2 includes an operational amplifier OP, resistors R ₁ and R ₂ and an inductor L _N to increase the inductance.

In more detail, its configuration, as shown, the inductor L _N is connected to the negative input terminal of the operational amplifier OP having two input terminals and one output terminal, and the positive terminal of the operational amplifier OP. A resistor R ₁ and a resistor R ₂ are connected between an input terminal, the output terminal, and a negative input terminal and the output terminal, respectively. The output terminal of the operational amplifier OP can in turn be connected via a resistor R ₁ to the later connected circuit denying power line modem side, not shown.

Meanwhile, the configuration of the present invention will be described with reference to FIG. 5, which shows in more detail the configuration of the power line coupler circuit for power line communication according to the present invention.

As shown in FIG. 5, a power line combiner circuit for power line communication according to the present invention is a circuit installed between a power line PL and a power line modem to process signal transmission and reception, and includes a power line combiner 1.

The power line combiner 1 includes a coupling transformer 1a and a coupling capacitor 1b and performs an interface function for transmitting and receiving a communication signal between the power line PL and the power line modem, that is, acts as an interface circuit. .

The power line coupler circuit for power line communication according to the present invention comprises a negative inductor circuit section 2.

The negative inductor circuit section 2 is a bandpass filter connected in parallel with the coupling transformer 1a between the power line modem and the coupling transformer, and the negative inductor circuit section 2 has a negative inductance and couples. The composite inductance with the magnetizing inductance of the ring transformer 1a increases, thereby minimizing the number of turns of the coupling transformer 1a and minimizing leakage inductance, thereby increasing the high pass cutoff frequency.

The negative inductor circuit unit 2 includes an inductor L _N and an operational amplifier OP connected in parallel with the coupling transformer 1a to increase the inductance, and two input terminals of the operational amplifier OP. And resistors R ₁ and R ₂ connected between the output terminals, respectively.

3 and 5, the negative inductor circuit portion 2 is connected in parallel to the coupling transformer 1a in disregard of the parasitic components of the coupling transformer 1a, so that the magnetization inductance of the coupling transformer 1a ( The combined inductance of L _C ) and the inductance (-L _N ) of the negative inductor circuit section 2 is obtained as follows.

이 된다.Composite inductance

Becomes

In the equation (5), if L _N = 1.1L _{C, the} synthetic inductance L _eq is 11L _C. That is, the composite inductance is increased by additionally connecting inductor circuit portions having negative inductance in parallel. If L _N = 1.01L _{C, the} composite inductance L _eq becomes 101L _C , thus increasing the inductance by 101 times. That is, the capacitance of the combined inductance can be increased by increasing the precision of the magnetizing inductance L _C and the inductance (-L _N ) of the negative inductor circuit portion 2.

Meanwhile, in FIG. 4, the synthesized impedance of the negative inductance converter, that is, the negative inductor circuit section 2 is as follows.

Here, Z _N is the resistance value of the combined impedance, s transfer function is shown, -L _N is an inductance, R ₂ and R ₁ in the negative inductor circuit portion (2) are each a resistance (R _2, R _1).

As shown in Equation (6), it can be seen that the impedance capacity of the negative inductor circuit unit 2 can be adjusted by the inductance of the inductor L _N and the resistance values of the resistors R ₂ and R ₁ .

If the resistance values of the resistors R ₂ and R ₁ are R _{1 =} R ₂ = 1 kΩ and the inductance of the inductor L _N is 75 μH, then the composite impedance Z _N = -75 μH of the negative inductor circuit section 2. When the magnetizing inductance Lc of the coupling transformer 1a is 70 μH, the inductor circuit 75 _N and the inductance L 75 of the inductor L _N and the magnetizing inductance Lc = 70 μH are substituted into the above formula (5). The synthetic inductance L _eq of (2) is 1050 µH. Therefore, the composite inductance with the coupling transformer 1a by the negative inductor circuit part 2 can be greatly increased from the magnetizing inductance Lc of the coupling transformer 1a = 70 μH to the composite inductance L _eq = 1050 μH. have.

The power line transmission and reception operation in the power line combiner circuit for power line communication according to the present invention constructed and acting as described above is as follows.

Upon reception of a signal through the power line, a signal obtained by combining a high frequency signal and a 60 Hz power signal to a negative inductor circuit portion 2 through a coupling capacitor 1b and a coupling transformer 1a, which are interface circuits. Is entered. Then, the negative inductor circuit unit 2 operates as a band pass filter to remove the low frequency power signal of 60 Hz, passes only the high frequency signal to be received, and then transfers the signal to the power line modem side of the figure, thereby completing the reception operation.

In the transmission of the signal through the power line, the high frequency signal to be transmitted passes through the negative inductor circuit section 2 which acts as a band pass filter, and by the coupling capacitor 1b and the coupling transformer 1a which are the interface circuits. The transmission operation is completed by being conveyed to the power line signal which is a low frequency commercial AC signal of 60 Hz.

On the other hand, with reference to Figure 6 showing the signal attenuation and frequency characteristics of the power line combiner circuit for power line communication according to the present invention acts as a bandpass filter as follows.

FIG. 6 is a capacitance value of the coupling capacitor 1b of the power line combiner circuit of FIG. 5 of 3.3 μF, and the primary winding resistance and the secondary winding resistances R _p1 and R _{p2 of the} coupling transformer 1a. ) Is 0.05 Ω, the primary winding leakage inductance and the secondary winding leakage inductance of the coupling transformer 1a are 0.01 μH, the magnetizing inductance Lc is 70 μH, respectively, and the resistance values of the resistors R ₁ , R ₂ are 1 kΩ, The inductance of the inductor L _N is 75 μH, the negative composite inductance of the negative inductor circuit section 2 (see symbol Z _{N in} FIG. 4) is -75 μH, and the power line impedance R _AC is 2 Ω (Ω). Is a signal characteristic diagram showing the magnitude characteristics of the signal according to the frequency. In Fig. 6, the pass frequency band has a low frequency lower limit of 23 kHz and a high frequency upper limit of 16 MHz with attenuation of -3 dB or more. The center frequency is 427 kHz and the signal attenuation at the center frequency is about 0.4 dB.

Accordingly, it can be seen that the bandwidth of the power line coupler circuit according to the prior art, which is introduced as FIGS. 1 and 2, is significantly larger than that of the low frequency lower limit of 224 kHz to the high frequency upper limit of 855 kHz, and the signal attenuation at the center frequency of the prior art is -1.6 dB. In comparison with the present invention, it can be seen that the signal is greatly improved as 0.4 dB.

According to the present invention, as the composite inductance caused by the negative inductor circuit portion increases, the number of turns of the coupling transformer does not need to be increased as in the prior art, so that a small core can be used and the size of the power line combiner circuit and the power line transceiver device It is possible to miniaturize and to manufacture a power line coupler circuit at a low cost.

According to the present invention, since the number of turns of the coupling transformer may be reduced, unlike the related art, a high performance power line coupler circuit may be obtained by minimizing parasitic components such as leakage inductance, winding resistance, and parasitic capacitance of the coupling transformer.

According to the present invention, since the number of turns of the coupling transformer can be reduced, the saturation problem caused by the increase of the alternating current caused by the increase in the capacity of the coupling capacitor, which is proportional to the increase in the number of turns of the coupling transformer, can be alleviated. It works.

 According to the present invention, the number of turns of the coupling transformer can be reduced by increasing the combined inductance of the negative inductor circuit portion and the coupling transformer, thereby reducing the leakage inductance, thereby increasing the high-frequency cutoff frequency in the passband of power line communication. There is an effect that can increase the passband.

Claims (9)

A power line combiner circuit for power line communication that processes signal transmission and reception between a power line and a power line modem, Coupling transformers; And In order to increase the passband of power line communication by increasing the high cutoff frequency in the passband of power line communication by increasing the combined inductance with the magnetizing inductance of the coupling transformer to minimize the number of turns of the coupling transformer to minimize leakage inductance. And an inductor converter having a negative inductance connected between the power line modem side and the coupling transformer. The method of claim 1, The inductor converter is connected in parallel to the coupling transformer. The method of claim 1, The inductor converter includes an operational amplifier, a resistor connected between the two input terminals and the output terminal of the operational amplifier so that the composite inductance is increased, and one end connected to the positive input terminal of the operational amplifier, and the other end is grounded. Power line combiner circuit for power line communication comprising a. The method of claim 3, wherein And said resistor is comprised of a variable resistor to enable precise adjustment of its resistance value. The method of claim 3, wherein And said inductor is comprised of a variable inductor to enable precise adjustment of its inductance value. A power line combiner circuit for power line communication, which is provided between a power line and a power line modem to process signal transmission and reception, A power line combiner having a coupling transformer and an alternating capacitor, and performing an interface for transmitting and receiving a communication signal between the power line and the power line modem; A bandpass filter connected in parallel with the coupling transformer between the power line modem and the coupling transformer, the bandpass filter having a negative inductance to increase the combined inductance with the magnetizing inductance of the coupling transformer to minimize the number of turns of the coupling transformer. And a negative inductor circuit unit configured to expand a passband bandwidth as a band pass filter at the same time. The method of claim 6, The negative inductor circuit section includes an inductor and an operational amplifier connected in parallel with the coupling transformer so that the composite inductance is increased, and a resistor connected between two input terminals and the output terminal of the operational amplifier, respectively. Coupling transformer circuit for power line communication. The method of claim 7, wherein And said resistor is comprised of a variable resistor to enable precise adjustment of its resistance value. The method of claim 7, wherein And said inductor is comprised of a variable inductor to enable precise adjustment of its inductance value.

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