CN212258956U

CN212258956U - Isolation circuit applied to power line carrier test system

Info

Publication number: CN212258956U
Application number: CN202020851840.XU
Authority: CN
Inventors: 李飞; 王鸿玺; 高波; 史轮; 付文杰; 申洪涛; 樊晓辉
Original assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd; State Grid Hebei Energy Technology Service Co Ltd
Current assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd; State Grid Hebei Energy Technology Service Co Ltd
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2020-12-29
Anticipated expiration: 2030-05-20

Abstract

The utility model discloses an isolation circuit applied to a power line carrier test system, relating to the technical field of power line carrier equipment test; the inductance filtering branch circuit consists of an L-line inductance filtering branch circuit and an N-line inductance filtering branch circuit which are identical in structure, the rated input impedance branch circuit is connected between the input end of the L-line inductance filtering branch circuit and the input end of the N-line inductance filtering branch circuit, and the rated output impedance branch circuit is connected between the output end of the L-line inductance filtering branch circuit and the output end of the N-line inductance filtering branch circuit; the isolation of the carrier frequency band of 100 KHz-12 MHz is realized by an inductive filtering branch circuit, a rated input impedance branch circuit, a rated output impedance branch circuit and the like.

Description

Isolation circuit applied to power line carrier test system

Technical Field

The utility model relates to a power line carrier device tests technical field, especially relates to an isolation circuit for power line carrier test system.

Background

The closest prior patents: CN105071835A, a wideband carrier communication attenuation circuit and coupling circuit.

The power line carrier communication refers to a communication method for transmitting data by means of a power line. The carrier test system is a platform for providing a test environment and a case for power line carrier communication equipment, and the carrier test platform in practical application faces two problems:

two or more carrier test systems interfere with each other.

Power line noise interferes, which is within the carrier band.

The interference in the carrier frequency band enters the carrier test system to affect the test result of the carrier module.

In order to ensure that the carrier test system is not interfered, an isolation device is needed to isolate other carrier signals or high-frequency interference signals. The isolator is a device for deeply attenuating an input high-frequency signal, can attenuate the high-frequency signal very little, and is applied more and more widely along with the development of the technology and the requirement of an electromagnetic compatibility test. At present, the power line carrier isolation equipment is less, and the following defects also exist:

the isolator is based on weak current design and cannot be used in power line carrier.

In order to meet the isolation requirement, the isolator is limited by the parameters of the existing device, can only allow a small-current 220V power line to pass, cannot supply power for the carrier test platform, and therefore is limited in use.

In a carrier test system, an isolator is required to have certain impedance, the carrier test result is influenced when the impedance is too small, and the isolation capability is reduced when the impedance is too large. The existing high-current isolator has the problem of low impedance, so that the test result is inaccurate; meanwhile, the isolator is large in size and inconvenient to use.

Problems with the prior art and considerations:

how to solve the technical problem of the isolation unit suitable for the carrier frequency range of 100 KHz-12 MHz.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that an isolation circuit for power line carrier test system is provided, it passes through inductance filtering branch road, rated input impedance branch road and rated output impedance branch road etc. has realized that 100 KHz-12 MHz carrier frequency range keeps apart.

In order to solve the technical problem, the utility model discloses the technical scheme who takes is: the utility model provides an isolation circuit for power line carrier test system includes inductance filtering branch road, rated input impedance branch road and rated output impedance branch road, inductance filtering branch road comprises the inductance filtering branch road of two L lines that the structure is the same and the inductance filtering branch road of N line, rated input impedance branch road is connected between the input of the inductance filtering branch road of L line and the input of the inductance filtering branch road of N line, rated output impedance branch road is connected between the output of the inductance filtering branch road of L line and the output of the inductance filtering branch road of N line.

The further technical scheme is as follows: the L-line inductance filtering branch is a first L-line inductance LL1, the N-line inductance filtering branch is a first N-line inductance LN1, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a joint 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a joint 2 of the first L-line inductance LL1 is an output end of the L-line inductance filtering branch, a joint 1 of the first L-line inductance LN1 is an input end of the N-line inductance filtering branch, a joint 2 of the first N-line inductance LN1 is an output end of the N-line inductance filtering branch, a joint 1 of the first L-line inductance LL1, a first resistor R1, a first capacitor C1 and a joint 1 of the first L-line inductance LN1 of the N-line are sequentially connected, and a joint 2 of the first L-line inductance LN1 is sequentially connected, The third resistor R3, the third capacitor C3 and the contact 2 of the first inductor LN1 of the N line are connected in sequence.

The further technical scheme is as follows: the L-line inductance filtering branch comprises a first L-line inductance LL1 and a second L-line inductance LL2, the N-line inductance filtering branch comprises a first N-line inductance LN1 and a second N-line inductance LN2, the rated input impedance branch is a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a joint 2 of the first L-line inductance LL1 is connected with a joint 1 of the second L-line inductance LL2, a joint 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a joint 2 of the second L-line inductance LL2 is an output end of the L-line inductance filtering branch, a joint 2 of the first N-line inductance LN1 is connected with a joint 1 of the second N-line inductance LN2, a joint 1 of the first N-line inductance LN1 is an input end of the N-line inductance filtering branch, a joint 2 of the second N-line inductance LN2 is an output end of the N-line inductance LN branch, the joint 1 of the first inductor LL1 of the L line, the first capacitor C1 and the joint 1 of the first inductor LN1 of the N line are connected in sequence, and the joint 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the joint 2 of the second inductor LN2 of the N line are connected in sequence.

The further technical scheme is as follows: the filter circuit further comprises a capacitance filtering branch which is a second capacitor C2, and the second capacitor C2 is connected between the connection position of the first inductor LL1 of the L line and the second inductor LL2 of the L line and the connection position of the first inductor LN1 of the N line and the second inductor LN2 of the N line.

The further technical scheme is as follows: the L-line inductance filtering branch comprises a first L-line inductance LL1 and a second L-line inductance LL2, the N-line inductance filtering branch comprises a first N-line inductance LN1 and a second N-line inductance LN2, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a connection point 2 of the first L-line inductance LL1 is connected with a connection point 1 of a second L-line inductance LL2, a connection point 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a connection point 2 of the second L-line inductance LL2 is an output end of the L-line inductance filtering branch, a connection point 2 of the first N-line inductance LN1 is connected with a connection point 1 of the second N-line inductance LN2, a connection point 1 of the first N-line inductance LN1 is an input end of the N-line inductance filtering branch, and a connection point 2 of the N-line inductance filtering branch is an output end of the N-line LN2, the junction 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1, and the junction 1 of the first inductor LN1 of the N line are connected in this order, and the junction 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3, and the junction 2 of the second inductor LN2 of the N line are connected in this order.

The further technical scheme is as follows: the first resistor R1 is a resistor with a value range of 0 ohm to 50 ohm, and the first resistor R1 is a chip resistor.

The further technical scheme is as follows: the first resistor R1 is a 0 ohm resistor.

The further technical scheme is as follows: the third resistor R3 is a resistor with a value range of 25-50 ohms, and the third resistor R3 is a chip resistor.

The further technical scheme is as follows: the rated input impedance branch comprises a first resistor R1 and a first capacitor C1, and the first resistor R1 is connected with the first capacitor C1.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

the utility model provides an isolation circuit for power line carrier test system includes inductance filtering branch road, rated input impedance branch road and rated output impedance branch road, inductance filtering branch road comprises the inductance filtering branch road of two L lines that the structure is the same and the inductance filtering branch road of N line, rated input impedance branch road is connected between the input of the inductance filtering branch road of L line and the input of the inductance filtering branch road of N line, rated output impedance branch road is connected between the output of the inductance filtering branch road of L line and the output of the inductance filtering branch road of N line. The isolation of the carrier frequency band of 100 KHz-12 MHz is realized by an inductive filtering branch circuit, a rated input impedance branch circuit, a rated output impedance branch circuit and the like.

See detailed description of the preferred embodiments.

Drawings

Fig. 1 is a schematic circuit diagram of embodiment 1 of the present invention;

fig. 2 is a schematic circuit diagram of embodiment 2 of the present invention;

fig. 3 is a schematic circuit diagram of embodiment 3 of the present invention;

FIG. 4 is a schematic diagram of an equivalent circuit of the power line of 220V/50Hz in the embodiments 2 and 3;

FIG. 5 is a schematic circuit diagram of the embodiment 2 for accessing a 220V/50Hz power line;

FIG. 6 is a schematic circuit diagram of an embodiment 3 for accessing a 220V/50Hz power line;

FIG. 7 is a simulation diagram of amplitude-frequency characteristics in example 2;

FIG. 8 is a simulation diagram of amplitude-frequency characteristics in example 3;

FIG. 9 is a 220V/50Hz industrial frequency input/output simulation diagram of examples 2 and 3.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways than those described herein, and it will be apparent to those of ordinary skill in the art that the present application is not limited to the specific embodiments disclosed below.

Example 1:

as shown in fig. 1, the utility model discloses an isolation circuit for power line carrier test system includes inductance filtering branch road, rated input impedance branch road, rated output impedance branch road and electric capacity filtering branch road, inductance filtering branch road comprises the inductance filtering branch road of two L lines that the structure is the same and the inductance filtering branch road of N line, rated input impedance branch road is connected between the input of the inductance filtering branch road of L line and the input of the inductance filtering branch road of N line, rated output impedance branch road is connected between the output of the inductance filtering branch road of L line and the output of the inductance filtering branch road of N line.

The inductance filtering branch of the L wire comprises first to X-th inductances LL 1-LLX of the L wire, the inductance filtering branch of the N wire comprises first to X-th inductances LN 1-LNX of the N wire, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting an X + 1-th resistor RX +1 and an X + 1-th capacitor CX +1, the first to X-th inductances LL 1-LLX of the L wire are sequentially connected in sequence, a joint 1 of the first inductance LL1 of the L wire is an input end of the inductance filtering branch of the L wire, a joint 2 of the X-th inductance LLX of the L wire is an output end of the inductance filtering branch of the L wire, the first to X-th inductances LN 1-LNX of the N wire are sequentially connected in sequence, a joint 1 of the first inductance LN1 of the N wire is an input end of the inductance filtering branch of the N wire, and a joint 2 of the X-th inductance LNX-th inductance filtering branch of the N wire is an output end of the inductance filtering branch of, a contact 1 of the L-line first inductor LL1, a first resistor R1, a first capacitor C1, and a contact 1 of the N-line first inductor LN1 are connected in this order, and a contact 2 of the L-line X-th inductor LLX, an X + 1-th resistor RX +1, an X + 1-th capacitor CX +1, and a contact 2 of the N-line X-th inductor LNX are connected in this order.

The capacitance filtering branch comprises X-1 capacitors, namely second capacitors to X capacitors C2-CX with the same structure, and the second capacitor C2 is connected between the connection position of a first inductor LL1 of the L line and a second inductor LL2 of the L line and the connection position of a first inductor LN1 of the N line and a second inductor LN2 of the N line.

Example 2:

as shown in fig. 2, the utility model discloses an isolation circuit for power line carrier test system includes inductance filtering branch road, rated input impedance branch road, rated output impedance branch road and electric capacity filtering branch road, inductance filtering branch road comprises the inductance filtering branch road of two L lines that the structure is the same and the inductance filtering branch road of N line, rated input impedance branch road is connected between the input of the inductance filtering branch road of L line and the input of the inductance filtering branch road of N line, rated output impedance branch road is connected between the output of the inductance filtering branch road of L line and the output of the inductance filtering branch road of N line.

The L-line inductance filtering branch comprises a first L-line inductance LL1 and a second L-line inductance LL2, the N-line inductance filtering branch comprises a first N-line inductance LN1 and a second N-line inductance LN2, the rated input impedance branch is a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a joint 2 of the first L-line inductance LL1 is connected with a joint 1 of the second L-line inductance LL2, a joint 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a joint 2 of the second L-line inductance LL2 is an output end of the L-line inductance filtering branch, a joint 2 of the first N-line inductance LN1 is connected with a joint 1 of the second N-line inductance LN2, a joint 1 of the first N-line inductance LN1 is an input end of the N-line inductance filtering branch, a joint 2 of the second N-line inductance LN2 is an output end of the N-line inductance LN branch, the joint 1 of the first inductor LL1 of the L line, the first capacitor C1 and the joint 1 of the first inductor LN1 of the N line are connected in sequence, and the joint 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the joint 2 of the second inductor LN2 of the N line are connected in sequence.

The capacitance filtering branch is a second capacitance C2, and the second capacitance C2 is connected between the connection of the first inductance LL1 of the L line and the second inductance LL2 of the L line and the connection of the first inductance LN1 of the N line and the second inductance LN2 of the N line.

Example 3:

as shown in fig. 3, the utility model discloses an isolation circuit for power line carrier test system includes inductance filtering branch road, rated input impedance branch road, rated output impedance branch road and electric capacity filtering branch road, inductance filtering branch road comprises the inductance filtering branch road of two L lines that the structure is the same and the inductance filtering branch road of N line, rated input impedance branch road is connected between the input of the inductance filtering branch road of L line and the input of the inductance filtering branch road of N line, rated output impedance branch road is connected between the output of the inductance filtering branch road of L line and the output of the inductance filtering branch road of N line.

The L-line inductance filtering branch comprises a first L-line inductance LL1 and a second L-line inductance LL2, the N-line inductance filtering branch comprises a first N-line inductance LN1 and a second N-line inductance LN2, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a connection point 2 of the first L-line inductance LL1 is connected with a connection point 1 of a second L-line inductance LL2, a connection point 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a connection point 2 of the second L-line inductance LL2 is an output end of the L-line inductance filtering branch, a connection point 2 of the first N-line inductance LN1 is connected with a connection point 1 of the second N-line inductance LN2, a connection point 1 of the first N-line inductance LN1 is an input end of the N-line inductance filtering branch, and a connection point 2 of the N-line inductance filtering branch is an output end of the N-line LN2, the junction 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1, and the junction 1 of the first inductor LN1 of the N line are connected in this order, and the junction 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3, and the junction 2 of the second inductor LN2 of the N line are connected in this order.

Example 4:

the utility model discloses a be applied to power line carrier test system's isolating circuit includes inductance filtering branch road, rated input impedance branch road and rated output impedance branch road, inductance filtering branch road comprises the inductance filtering branch road of two L lines that the structure is the same and the inductance filtering branch road of N line, rated input impedance branch road is connected between the input of the inductance filtering branch road of L line and the input of the inductance filtering branch road of N line, rated output impedance branch road is connected between the output of the inductance filtering branch road of L line and the output of the inductance filtering branch road of N line.

The L-line inductance filtering branch is a first L-line inductance LL1, the N-line inductance filtering branch is a first N-line inductance LN1, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a joint 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a joint 2 of the first L-line inductance LL1 is an output end of the L-line inductance filtering branch, a joint 1 of the first L-line inductance LN1 is an input end of the N-line inductance filtering branch, a joint 2 of the first N-line inductance LN1 is an output end of the N-line inductance filtering branch, a joint 1 of the first L-line inductance LL1, a first resistor R1, a first capacitor C1 and a joint 1 of the first L-line inductance LN1 of the N-line are sequentially connected, and a joint 2 of the first L-line inductance LN1 is sequentially connected, The third resistor R3, the third capacitor C3 and the contact 2 of the first inductor LN1 of the N line are connected in sequence.

The utility model discloses the design of this application:

the utility model aims to solve the technical problem that an isolator circuit for power line carrier test system is provided, isolator circuit passes through x rank low pass filter technique, realizes that power line 220V 10A is lossless to pass through, and reaches 75dB and above decay to 100 KHz-12 MHz carrier frequency in-band, provides comparatively clean test environment for carrier equipment.

First, the main subject of the solution is an x-order low-pass filter. In the prior art, a resistor is connected with a capacitor in series in each branch trunk circuit and then connected with the main trunk circuit so as to attenuate signals. However, each branch trunk adopts a resistor and capacitor series connection mode, which causes the limitation of the signal attenuation capability of the isolator, and other carrier signals or interference signals cannot be isolated in the carrier test system, thereby affecting the test of the carrier module. Utility model people discover, through reforming transform traditional wave filter, change x +1 level also namely last one-level branch road series resistance into 25-50 ohm, remove other branch road series resistance, can effectual promotion isolator attenuation ability.

Second, a high current high frequency inductor. The inductance parameter of the prior art is generally large inductance, small rated current, large inductance, large rated current and low working frequency, and the inductance can not be applied to a carrier test system of 10A, 100 KHz-12 MHz. The utility model discloses the people discovers, through adopting nickel zinc high frequency magnetic ring and manganese zinc low frequency magnetic ring dual magnetic ring to combine the coiling inductance, can satisfy 10A, 100 KHz-12 MHz operating condition.

Technical contribution of the present application:

in order to solve the technical problem, the utility model discloses the technical scheme who takes is: the high-frequency high-current power supply comprises an x-order LC low-pass filter circuit, high-frequency high-current inductors LL (1 ﹍ x) and LN (1 ﹍ x), rated input impedance circuits R1 and C1, rated output impedance circuits Cx +1 and Rx +1, a power-frequency input P1 port and a power-frequency output P2 port.

The x-order LC low-pass filter circuit comprises two main trunk circuits formed by connecting x inductors in series and a middle branch circuit formed by connecting capacitors, wherein the middle branch circuit is formed by x-2 capacitors, and x is a natural number greater than 2.

The high-frequency large-current inductors LL (1 ﹍ x) and LN (1 ﹍ x) allow 10A of current to pass through and have rated inductance in a carrier frequency band of 100 KHz-12 MHz.

The rated input impedance circuits R1 and C1 are formed by connecting a branch 1 trunk capacitor C1 and a resistor R1 in series, and the capacitive reactance of the capacitor is very small and negligible in a carrier frequency band, so that the input impedance is almost equal to the resistance value of the resistor R1.

The rated output impedance circuits Cx +1 and Rx +1 are formed by connecting an xth branch circuit capacitor CX +1 and a resistor RX +1 in series, and similarly, the output impedance is almost equal to the resistance value of the resistor RX + 1.

The power frequency input P1 port refers to an isolator 220V/50Hz input port.

The power frequency output P2 port refers to an isolator 220V/50Hz output port.

In the above scheme, the attenuation value of the isolation circuit is:

A＝20log(A_x×A_x-1×A₂)

i＝1,2,…,x-1

wherein A is the attenuation value of the isolation circuit, A_iIs the attenuation value of the i-order low-pass filter, f is the signal frequency, R_x+1Is branch x +1 trunk resistance, C_x+1Is the x +1 branch trunk circuit safety-regulation capacitor, LL_xIs a main line Lx high-frequency large-current inductor, LN_xIs a main line Nx high-frequency large-current inductor, C_i+1Is the i +1 branch trunk circuit safety capacitor, LL_iIs a main line Li high-frequency large-current inductor, LN_iThe Ni high-frequency large-current inductor is a main line Ni high-frequency large-current inductor, and i is a natural number which is larger than 1 and smaller than x-1.

The further technical scheme is as follows: the value range of the rated input impedance circuit resistor R1 is 0-50 ohms, and when the value of the resistor is 0 ohm, the isolation effect is optimal; with the increase of the resistance value of the resistor, the isolation effect is gradually reduced; the maximum resistance allowed is 50 ohms; the rated input impedance circuit resistor R1 is a chip resistor and has good high-frequency performance.

The further technical scheme is as follows: the resistor R3 of the rated output impedance circuit has the value range of 25-50 ohms, when the resistor R3 is 0 ohm, the isolation effect is optimal, but the performance of the tested carrier module is affected, so the resistor R3 is not recommended to be adopted, and the optimal value range is 25-50 ohms. The rated input impedance circuit resistor R3 is a chip resistor and has good high-frequency performance.

The further technical scheme is as follows: as the operating frequency increases, the characteristics of LL (1 ﹍ x), LN (1 ﹍ x), C1 and Cx +1 change, i.e. there is a self-resonant frequency, when the operating frequency is higher than the self-resonant frequency, the inductance is capacitive, and the capacitance is inductive, so that the high-frequency large-current inductors LL (1 ﹍ x) and LN (1 ﹍ x) need to have a self-resonant frequency point higher than 12 MHz. In the technical scheme, the high-frequency large-current inductors LL (1 ﹍ x) and LN (1 ﹍ x) are wound by double magnetic ring wires of a nickel-zinc high-frequency magnetic ring and a manganese-zinc low-frequency magnetic ring, the nickel-zinc high-frequency magnetic ring has the characteristics of low magnetic conductivity and high resistivity, the inductor still presents the inductance under high frequency, and the manganese-zinc low-frequency magnetic ring has the characteristics of high magnetic conductivity and low resistivity, so that the required inductance is ensured.

The technical scheme is as follows:

example 1 illustrates that:

as shown in fig. 1, the utility model discloses an isolation circuit for power line carrier test system, this isolation circuit includes: the high-frequency high-current power supply comprises an x-order LC low-pass filter circuit, high-frequency high-current inductors LL (1 ﹍ x) and LN (1 ﹍ x), rated input impedance circuits R1 and C1, rated output impedance circuits Cx +1 and Rx +1, a power-frequency input P1 port and a power-frequency output P2 port. The power frequency input P1 port is used for accessing a 220V/50Hz power line, and the power line comprises a carrier signal of 100 KHz-12 MHz and other high-frequency interference signals; the signals are attenuated to signals without influence on a carrier test system after passing through rated input impedance circuits R1 and C1 and an x-order LC low-pass filter, and a 220V/50Hz power line passes through without loss; the nominal output impedance circuits Cx +1 and Rx +1 provide nominal impedance for the carrier test system. And the power frequency output P2 port is accessed to a power supply port of the carrier test system to provide a clean power line for the test system.

Example 2 illustrates that:

as shown in fig. 2, in simplified embodiment 1, the rated input impedance circuit is formed only by C1, and the isolation circuit includes: 4-order LC low-pass filter circuit, high-frequency large-current inductors LL1, LN1, LL2 and LN2, and rated output impedance circuits C3 and R3.

Example 3 illustrates that:

as shown in fig. 3, in the technique of embodiment 2, rated input impedance circuits R1 and C1 are added. The isolation circuit has a rated input impedance and a rated output impedance, and although the isolation performance of embodiment 3 is slightly inferior to that of embodiment 2, the isolation circuit can be applied to a carrier-level communication structure.

Fig. 4 is a schematic diagram of the access of 220V/50Hz power lines in embodiments 2 and 3, and the branch lines are disconnected from the power lines. The power line is input from a power frequency input P1 port, passes through high-frequency large-current inductors LL1, LN1, LL2 and LN2 and is output from a power frequency output P2 port.

FIG. 5 shows a circuit diagram of the 220V/50Hz power line access in the embodiment 2:

R_inis the power line source impedance, R_inThe input equivalent impedance formed by the input rated impedance circuit and the 4-order LC low-pass filter circuit is as follows:

wherein R is_e-5The equivalent impedance is input for fig. 5.

Isolation circuit output impedance R_o-2Comprises the following steps:

at this time, the attenuation values of the isolation circuit are:

wherein A is_fig5The attenuation values of fig. 5.

If taking C₁＝C₂＝C₃＝C，LL₁＝LN₁＝LN₂＝LN₂When L, the attenuation of the isolation circuit is:

FIG. 6 shows the circuit diagram of the 220V/50Hz power line access in the embodiment 3:

wherein R is_e-6The equivalent impedance is input for fig. 6.

Isolation circuit output impedance R_o-3Comprises the following steps:

at this time, the attenuation values of the isolation circuit are:

wherein A is_fig6The attenuation values of fig. 6.

as shown in FIG. 7, the simulation results of the amplitude-frequency characteristics, R, of the embodiment of FIG. 5 are obtained_inIs 50 ohm, R₁Is 0 ohm, R₃Is 50 ohm, C₁＝C₂＝C₃＝220nF，LL₁＝LN₁＝LN₂＝LN₂As 470uH, the attenuation of the isolation circuit at 100KHz is about 76dB, and the attenuation increases as the frequency of the signal increases.

As shown in FIG. 8, the simulation results of the amplitude-frequency characteristics, R, of the embodiment of FIG. 6 were obtained_inIs 50 ohm, R₁＝R₃Is 50 ohm, C₁＝C₂＝C₃＝220nF，LL₁＝LN₁＝LN₂＝LN₂As can be seen from 470uH, the attenuation of the isolation circuit at 100KHz is about 65dB, and compared with fig. 5, the attenuation performance of example 3 is 11dB lower than that of example 2. This result is best matched with the isolation performance mentioned in the above solution when R1 is 0 ohms.

As shown in FIG. 9, the 220V/50Hz power line can pass through the present embodiment 2 and the present embodiment 3 without distortion by simulating the 220V/50Hz power line input for the embodiment 2 and the embodiment 3. Similarly, the present embodiment 1 may be applied without distortion.

After the application runs secretly for a period of time, the feedback of field technicians has the advantages that:

firstly, the isolation effect is good. Through actual test, the isolator can realize that the 220V/10A power line passes through without loss, and can attenuate signals within a frequency band of 100 KHz-12 MHz to 75dB or above, thereby meeting the isolation requirement of a carrier test system.

Secondly, in the x +1 branch trunk circuit, the 1 st branch trunk circuit and the x +1 st branch trunk circuit are removed, and the middle x-2 branch trunk circuit capacitor is directly connected with the two trunk circuits without series resistors, so that the cost is reduced.

And thirdly, the performance of the carrier module tested by the carrier testing system is not influenced.

Claims

1. The utility model provides an isolation circuit for power line carrier test system which characterized in that: the inductance filtering branch circuit comprises an inductance filtering branch circuit, a rated input impedance branch circuit and a rated output impedance branch circuit, wherein the inductance filtering branch circuit comprises an L-line inductance filtering branch circuit and an N-line inductance filtering branch circuit which are identical in structure, the rated input impedance branch circuit is connected between the input end of the L-line inductance filtering branch circuit and the input end of the N-line inductance filtering branch circuit, and the rated output impedance branch circuit is connected between the output end of the L-line inductance filtering branch circuit and the output end of the N-line inductance filtering branch circuit.

2. The isolation circuit applied to the power line carrier test system according to claim 1, wherein: the L-line inductance filtering branch is a first L-line inductance LL1, the N-line inductance filtering branch is a first N-line inductance LN1, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a joint 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a joint 2 of the first L-line inductance LL1 is an output end of the L-line inductance filtering branch, a joint 1 of the first L-line inductance LN1 is an input end of the N-line inductance filtering branch, a joint 2 of the first N-line inductance LN1 is an output end of the N-line inductance filtering branch, a joint 1 of the first L-line inductance LL1, a first resistor R1, a first capacitor C1 and a joint 1 of the first L-line inductance LN1 of the N-line are sequentially connected, and a joint 2 of the first L-line inductance LN1 is sequentially connected, The third resistor R3, the third capacitor C3 and the contact 2 of the first inductor LN1 of the N line are connected in sequence.

3. The isolation circuit applied to the power line carrier test system according to claim 1, wherein: the L-line inductance filtering branch comprises a first L-line inductance LL1 and a second L-line inductance LL2, the N-line inductance filtering branch comprises a first N-line inductance LN1 and a second N-line inductance LN2, the rated input impedance branch is a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a joint 2 of the first L-line inductance LL1 is connected with a joint 1 of the second L-line inductance LL2, a joint 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a joint 2 of the second L-line inductance LL2 is an output end of the L-line inductance filtering branch, a joint 2 of the first N-line inductance LN1 is connected with a joint 1 of the second N-line inductance LN2, a joint 1 of the first N-line inductance LN1 is an input end of the N-line inductance filtering branch, a joint 2 of the second N-line inductance LN2 is an output end of the N-line inductance LN branch, the joint 1 of the first inductor LL1 of the L line, the first capacitor C1 and the joint 1 of the first inductor LN1 of the N line are connected in sequence, and the joint 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the joint 2 of the second inductor LN2 of the N line are connected in sequence.

4. The isolation circuit applied to the power line carrier test system according to claim 3, wherein: the filter circuit further comprises a capacitance filtering branch which is a second capacitor C2, and the second capacitor C2 is connected between the connection position of the first inductor LL1 of the L line and the second inductor LL2 of the L line and the connection position of the first inductor LN1 of the N line and the second inductor LN2 of the N line.

5. The isolation circuit applied to the power line carrier test system according to claim 1, wherein: the L-line inductance filtering branch comprises a first L-line inductance LL1 and a second L-line inductance LL2, the N-line inductance filtering branch comprises a first N-line inductance LN1 and a second N-line inductance LN2, the rated input impedance branch is formed by connecting a first resistor R1 and a first capacitor C1, the rated output impedance branch is formed by connecting a third resistor R3 and a third capacitor C3, a connection point 2 of the first L-line inductance LL1 is connected with a connection point 1 of a second L-line inductance LL2, a connection point 1 of the first L-line inductance LL1 is an input end of the L-line inductance filtering branch, a connection point 2 of the second L-line inductance LL2 is an output end of the L-line inductance filtering branch, a connection point 2 of the first N-line inductance LN1 is connected with a connection point 1 of the second N-line inductance LN2, a connection point 1 of the first N-line inductance LN1 is an input end of the N-line inductance filtering branch, and a connection point 2 of the N-line inductance filtering branch is an output end of the N-line LN2, the junction 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1, and the junction 1 of the first inductor LN1 of the N line are connected in this order, and the junction 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3, and the junction 2 of the second inductor LN2 of the N line are connected in this order.

6. The isolation circuit applied to the power line carrier test system according to claim 5, wherein: the filter circuit further comprises a capacitance filtering branch which is a second capacitor C2, and the second capacitor C2 is connected between the connection position of the first inductor LL1 of the L line and the second inductor LL2 of the L line and the connection position of the first inductor LN1 of the N line and the second inductor LN2 of the N line.

7. The isolation circuit applied to the power line carrier test system according to claim 2 or 5, wherein: the first resistor R1 is a resistor with a value range of 0 ohm to 50 ohm, and the first resistor R1 is a chip resistor.

8. The isolation circuit applied to the power line carrier test system according to claim 7, wherein: the first resistor R1 is a 0 ohm resistor.

9. The isolation circuit applied to the power line carrier test system according to claim 2, 3 or 5, wherein: the third resistor R3 is a resistor with a value range of 25-50 ohms, and the third resistor R3 is a chip resistor.

10. The isolation circuit applied to the power line carrier test system according to claim 1, wherein: the rated input impedance branch comprises a first resistor R1 and a first capacitor C1, and the first resistor R1 is connected with the first capacitor C1.