An isolation circuit used in power line carrier test system

Abstract

The invention discloses an isolation circuit applied to a power line carrier test system, and relates to the technical field of power line carrier equipment testing; the isolation circuit comprises an inductance filter branch, a rated input impedance branch and a rated output impedance branch, wherein the inductance filter branch is composed of two L-line inductance filter branches and an N-line inductance filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductance filter branch and the input end of the N-line inductance filter branch, and the rated output impedance branch is connected between the output end of the L-line inductance filter branch and the output end of the N-line inductance filter branch; the isolation circuit realizes 100KHz-12MHz carrier frequency band isolation through the inductance filter branch, the rated input impedance branch and the rated output impedance branch.

Description

Technical Field

[0001] The invention relates to the technical field of power line carrier equipment testing, and in particular to an isolation circuit applied to a power line carrier testing system. Background Art

[0002] The closest existing patent: CN105071835A, a broadband carrier communication attenuation circuit and coupling circuit.

[0003] Power line carrier communication refers to a communication method that uses power lines to transmit data. The carrier test system is a platform that provides a test environment and use cases for power line carrier communication equipment. In actual applications, the carrier test platform faces two problems:

[0004] Two or more carrier test systems interfere with each other.

[0005] Power line noise interference, this interference is within the carrier frequency band.

[0006] The above interference within the carrier frequency band enters the carrier test system and affects the test results of the carrier module.

[0007] In order to ensure that the carrier test system is not interfered with, isolation equipment is needed to isolate other carrier signals or high-frequency interference signals. An isolator is a device that deeply attenuates the input high-frequency signal, which can attenuate the high-frequency signal to a very small extent. With the development of technology and the requirements of electromagnetic compatibility testing, the application of isolators is becoming more and more extensive. At present, there are few power line carrier isolation devices, and there are also the following shortcomings:

[0008] The isolator is based on weak current design and cannot be used in power line carrier.

[0009] In order to meet the isolation requirements, the isolator is limited by the existing device parameters and can only allow small current 220V power lines to pass through. It cannot power the carrier test platform, so its use is limited.

[0010] In the carrier test system, the isolator is required to have a certain impedance. Too small impedance will affect the carrier test results, and too large impedance will reduce the isolation capability. Existing high-current isolators have low impedance problems, resulting in inaccurate test results; at the same time, the isolator is large in size and inconvenient to use.

[0011] Existing technical problems and considerations:

[0012] How to solve the technical problem of isolation unit suitable for 100KHz-12MHz carrier frequency band. Summary of the invention

[0013] The technical problem to be solved by the present invention is to provide an isolation circuit applied to a power line carrier test system, which realizes 100KHz-12MHz carrier frequency band isolation through an inductor filter branch, a rated input impedance branch and a rated output impedance branch.

[0014] In order to solve the above technical problems, the technical solution adopted by the present invention is: an isolation circuit applied to a power line carrier test system includes an inductor filter branch, a rated input impedance branch and a rated output impedance branch, the inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch, and the rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch.

[0015] A further technical solution is that: the inductance filter branch of the L line is the first inductance LL1 of the L line, the inductance filter branch of the N line is the first inductance LN1 of the N line, the rated input impedance branch is composed of a first resistor R1 and a first capacitor C1 connected, the rated output impedance branch is composed of a third resistor R3 and a third capacitor C3 connected, the contact 1 of the first inductance LL1 of the L line is the input end of the inductance filter branch of the L line, the contact 2 of the first inductance LL1 of the L line is the output end of the inductance filter branch of the L line, the contact 1 of the first inductance LN1 of the N line is the input end of the inductance filter branch of the N line, the contact 2 of the first inductance LN1 of the N line is the output end of the inductance filter branch of the N line, the contact 1 of the first inductance LL1 of the L line, the first resistor R1, the first capacitor C1 and the contact 1 of the first inductance LN1 of the N line are connected in sequence, and the contact 2 of the first inductance LL1 of the L line, the third resistor R3, the third capacitor C3 and the contact 2 of the first inductance LN1 of the N line are connected in sequence.

[0016] A further technical solution is that: the inductor filter branch of the L line includes a first inductor LL1 and a second inductor LL2 of the L line, the inductor filter branch of the N line includes a first inductor LN1 and a second inductor LN2 of the N line, the rated input impedance branch is a first capacitor C1, the rated output impedance branch is composed of a third resistor R3 and a third capacitor C3, the contact 2 of the first inductor LL1 of the L line is connected to the contact 1 of the second inductor LL2 of the L line, the contact 1 of the first inductor LL1 of the L line is the input end of the inductor filter branch of the L line, and the contact 2 of the second inductor LL2 of the L line is the input end of the inductor filter branch of the L line. Point 2 is the output end of the inductor filter branch of the L line, the contact point 2 of the first inductor LN1 of the N line is connected to the contact point 1 of the second inductor LN2 of the N line, the contact point 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact point 2 of the second inductor LN2 of the N line is the output end of the inductor filter branch of the N line, the contact point 1 of the first inductor LL1 of the L line, the first capacitor C1 and the contact point 1 of the first inductor LN1 of the N line are connected in sequence, and the contact point 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the contact point 2 of the second inductor LN2 of the N line are connected in sequence.

[0017] A further technical solution is: it also includes a capacitor filtering branch, the capacitor filtering branch is a second capacitor C2, and the second capacitor C2 is connected between the connection between the first inductor LL1 of the L line and the second inductor LL2 of the L line and the connection between the first inductor LN1 of the N line and the second inductor LN2 of the N line.

[0018] A further technical solution is that: the inductance filter branch of the L line includes a first inductance LL1 and a second inductance LL2 of the L line, the inductance filter branch of the N line includes a first inductance LN1 and a second inductance LN2 of the N line, the rated input impedance branch is composed of a first resistor R1 and a first capacitor C1, the rated output impedance branch is composed of a third resistor R3 and a third capacitor C3, the contact 2 of the first inductance LL1 of the L line is connected to the contact 1 of the second inductance LL2 of the L line, the contact 1 of the first inductance LL1 of the L line is the input end of the inductance filter branch of the L line, and the second inductance LL2 of the L line is connected to the input end of the inductance filter branch of the L line. The contact point 2 of the first inductor LN1 of the N line is the output end of the inductor filter branch of the L line, the contact point 2 of the first inductor LN1 of the N line is connected to the contact point 1 of the second inductor LN2 of the N line, the contact point 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact point 2 of the second inductor LN2 of the N line is the output end of the inductor filter branch of the N line, the contact point 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1 and the contact point 1 of the first inductor LN1 of the N line are connected in sequence, and the contact point 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the contact point 2 of the second inductor LN2 of the N line are connected in sequence.

[0019] A further technical solution is: it also includes a capacitor filtering branch, the capacitor filtering branch is a second capacitor C2, and the second capacitor C2 is connected between the connection between the first inductor LL1 of the L line and the second inductor LL2 of the L line and the connection between the first inductor LN1 of the N line and the second inductor LN2 of the N line.

[0020] A further technical solution is that: the first resistor R1 is a resistor with a value range of 0 ohm to 50 ohms, and the first resistor R1 is a chip resistor.

[0021] A further technical solution is that: the first resistor R1 is a resistor of 0 ohm.

[0022] A further technical solution is that: the third resistor R3 is a resistor with a value range of 25 ohms to 50 ohms, and the third resistor R3 is a chip resistor.

[0023] A further technical solution is that: the rated input impedance branch includes a first resistor R1 and a first capacitor C1, and the first resistor R1 is connected to the first capacitor C1.

[0024] The beneficial effects of adopting the above technical solution are:

[0025] An isolation circuit applied to a power line carrier test system includes an inductor filter branch, a rated input impedance branch and a rated output impedance branch. The inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure. The rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch. The rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch. The isolation circuit realizes the 100KHz-12MHz carrier frequency band isolation through the inductor filter branch, the rated input impedance branch and the rated output impedance branch.

[0026] Please refer to the detailed description of the specific implementation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a circuit diagram of embodiment 1 of the present invention;

[0028] Figure 2 is a circuit schematic diagram of embodiment 2 of the present invention;

[0029] Figure 3 is a circuit diagram of Embodiment 3 of the present invention;

[0030] Figure 4 is an equivalent circuit schematic diagram of Embodiment 2 and Embodiment 3 under 220V / 50Hz industrial frequency power line;

[0031] Figure 5 This is a circuit schematic diagram of Example 2 connected to a 220V / 50Hz power line;

[0032] Figure 6 This is a circuit schematic diagram of Example 3 connected to a 220V / 50Hz power line;

[0033] Figure 7 is a simulation diagram of the amplitude-frequency characteristic in Example 2;

[0034] Figure 8 is a simulation diagram of the amplitude-frequency characteristic in Example 3;

[0035] Fig. 9 It is a 220V / 50Hz industrial frequency input and output simulation diagram of Example 2 and Example 3. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0038] Embodiment 1:

[0039] like Figure 1 As shown, the present invention discloses an isolation circuit applied to a power line carrier test system, comprising an inductor filter branch, a rated input impedance branch, a rated output impedance branch and a capacitor filter branch, wherein the inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch, and the rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch.

[0040] The inductor filter branch of the L line includes the first to Xth inductors LL1~LLX of the L line, the inductor filter branch of the N line includes the first to Xth inductors LN1~LNX of the N line, the rated input impedance branch is formed by connecting the first resistor R1 and the first capacitor C1, the rated output impedance branch is formed by connecting the X+1th resistor RX+1 and the X+1th capacitor CX+1, the first to Xth inductors LL1~LLX of the L line are connected in sequence, the contact 1 of the first inductor LL1 of the L line is the input end of the inductor filter branch of the L line, the contact 2 of the Xth inductor LLX of the L line is the L line The output end of the inductor filter branch of the N line, the first to Xth inductors LN1~LNX of the N line are connected in sequence, the contact 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact 2 of the Xth inductor LNX of the N line is the output end of the inductor filter branch of the N line, the contact 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1 and the contact 1 of the first inductor LN1 of the N line are connected in sequence, the contact 2 of the Xth inductor LLX of the L line, the X+1th resistor RX+1, the X+1th capacitor CX+1 and the contact 2 of the Xth inductor LNX of the N line are connected in sequence.

[0041] The capacitor filter branch includes X-1 capacitors, which are the second to Xth capacitors C2~CX with the same structure. The second capacitor C2 is connected between the connection between the first inductor LL1 of the L line and the second inductor LL2 of the L line and the connection between the first inductor LN1 of the N line and the second inductor LN2 of the N line.

[0042] Embodiment 2:

[0043] like Figure 2 As shown, the present invention discloses an isolation circuit applied to a power line carrier test system, comprising an inductor filter branch, a rated input impedance branch, a rated output impedance branch and a capacitor filter branch, wherein the inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch, and the rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch.

[0044] The inductor filter branch of the L line includes a first inductor LL1 and a second inductor LL2 of the L line, the inductor filter branch of the N line includes a first inductor LN1 and a second inductor LN2 of the N line, 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 contact point 2 of the first inductor LL1 of the L line is connected to a contact point 1 of the second inductor LL2 of the L line, the contact point 1 of the first inductor LL1 of the L line is the input end of the inductor filter branch of the L line, and a contact point 2 of the second inductor LL2 of the L line is the output end of the L line. At the output end of the inductor filter branch, the contact 2 of the first inductor LN1 of the N line is connected to the contact 1 of the second inductor LN2 of the N line, the contact 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact 2 of the second inductor LN2 of the N line is the output end of the inductor filter branch of the N line, the contact 1 of the first inductor LL1 of the L line, the first capacitor C1 and the contact 1 of the first inductor LN1 of the N line are connected in sequence, and the contact 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the contact 2 of the second inductor LN2 of the N line are connected in sequence.

[0045] The capacitor filtering branch is a second capacitor C2, which is connected between a connection point between a first inductor LL1 of the L line and a second inductor LL2 of the L line and a connection point between a first inductor LN1 of the N line and a second inductor LN2 of the N line.

[0046] Embodiment 3:

[0047] like Figure 3 As shown, the present invention discloses an isolation circuit applied to a power line carrier test system, comprising an inductor filter branch, a rated input impedance branch, a rated output impedance branch and a capacitor filter branch, wherein the inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch, and the rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch.

[0048] The inductor filter branch of the L line includes a first inductor LL1 and a second inductor LL2 of the L line, the inductor filter branch of the N line includes a first inductor LN1 and a second inductor LN2 of the N line, 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 contact point 2 of the first inductor LL1 of the L line is connected to a contact point 1 of the second inductor LL2 of the L line, the contact point 1 of the first inductor LL1 of the L line is the input end of the inductor filter branch of the L line, and a contact point 2 of the second inductor LL2 of the L line is the L The output end of the inductor filter branch of the N line, the contact point 2 of the first inductor LN1 of the N line is connected to the contact point 1 of the second inductor LN2 of the N line, the contact point 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact point 2 of the second inductor LN2 of the N line is the output end of the inductor filter branch of the N line, the contact point 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1 and the contact point 1 of the first inductor LN1 of the N line are connected in sequence, and the contact point 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the contact point 2 of the second inductor LN2 of the N line are connected in sequence.

[0049] The capacitor filtering branch is a second capacitor C2, which is connected between a connection point between a first inductor LL1 of the L line and a second inductor LL2 of the L line and a connection point between a first inductor LN1 of the N line and a second inductor LN2 of the N line.

[0050] Embodiment 4:

[0051] The invention discloses an isolation circuit applied to a power line carrier test system, comprising an inductor filter branch, a rated input impedance branch and a rated output impedance branch, wherein the inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch, and the rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch.

[0052] The inductance filter branch of the L line is the first inductance LL1 of the L line, the inductance filter branch of the N line is the first inductance LN1 of the N line, the rated input impedance branch is composed of a first resistor R1 and a first capacitor C1, the rated output impedance branch is composed of a third resistor R3 and a third capacitor C3, the contact 1 of the first inductance LL1 of the L line is the input end of the inductance filter branch of the L line, the contact 2 of the first inductance LL1 of the L line is the output end of the inductance filter branch of the L line, the contact 1 of the first inductance LN1 of the N line is the input end of the inductance filter branch of the N line, the contact 2 of the first inductance LN1 of the N line is the output end of the inductance filter branch of the N line, the contact 1 of the first inductance LL1 of the L line, the first resistor R1, the first capacitor C1 and the contact 1 of the first inductance LN1 of the N line are connected in sequence, and the contact 2 of the first inductance LL1 of the L line, the third resistor R3, the third capacitor C3 and the contact 2 of the first inductance LN1 of the N line are connected in sequence.

[0053] The inventive concept of this application:

[0054] The technical problem to be solved by the present invention is to provide an isolation circuit applied to a power line carrier test system. The isolation circuit uses an x-order low-pass filter technology to achieve lossless passage of the power line 220V / 10A, and achieves 75dB or more attenuation in the 100KHz-12MHz carrier frequency band, providing a relatively clean test environment for the carrier equipment.

[0055] First, the main body of the technical solution is an x-order low-pass filter. The prior art generally uses resistors and capacitors in series in each branch road and then connects them to the main road in order to attenuate the signal. However, the use of resistors and capacitors in series in each branch road will limit the signal attenuation ability of the isolator, and other carrier signals or interference signals cannot be isolated in the carrier test system, affecting the carrier module test. The inventors found that by modifying the traditional filter, changing the resistance value of the series resistor of the x+1 level, which is the last level of the branch road, to 25-50 ohms, and removing the series resistors of other branch roads, the attenuation capacity of the isolator will be effectively improved.

[0056] Second, high-current and high-frequency inductors. The inductor parameters of the prior art are generally large inductance and small rated current, small inductance and large rated current, and large inductance and large rated current and low operating frequency. Such inductors cannot be used in 10A, 100KHz-12MHz carrier test systems. The inventors found that by using a combination of nickel-zinc high-frequency magnetic rings and manganese-zinc low-frequency magnetic rings to wind the inductor, the 10A, 100KHz-12MHz operating conditions can be met.

[0057] Technical contributions of this application:

[0058] In order to solve the above technical problems, the technical solution adopted by the present invention is: x-order LC low-pass filter circuit, high-frequency and 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, industrial frequency input port P1 and industrial frequency output port P2.

[0059] The x-order LC low-pass filter circuit includes two main trunks formed by x inductors connected in series and an intermediate branch trunk formed by capacitors. The intermediate branch trunk is composed of x-2 capacitors, where x is a natural number greater than 2.

[0060] The high-frequency, high-current inductors LL (1﹍x) and LN (1﹍x) allow a current of 10A to pass through and have a rated inductance within a carrier frequency band of 100KHz-12MHz.

[0061] The rated input impedance circuit R1 and C1 is composed of the first branch main circuit capacitor C1 and the resistor R1 in series. The capacitive reactance is very small and negligible within the carrier frequency band, so the input impedance is almost equal to the resistance value of the resistor R1.

[0062] The rated output impedance circuits Cx+1 and Rx+1 are composed of an x-th branch main circuit capacitor CX+1 and a resistor RX+1 connected in series. Similarly, the output impedance is almost equal to the resistance value of the resistor RX+1.

[0063] The power frequency input P1 port refers to the isolator 220V / 50Hz input port.

[0064] The industrial frequency output P2 port refers to the isolator 220V / 50Hz output port.

[0065] In the above scheme, the attenuation value of the isolation circuit is:

[0066] A=20log(A x ×A x-1 ×A2)

[0067]

[0068]

[0069] Where A is the attenuation value of the isolation circuit, A i is the attenuation value of the i-th order low-pass filter, f is the signal frequency, R x+1 is the x+1th branch trunk resistance, C x+1 is the x+1th branch safety capacitor, LL x For the main line Lx high frequency and high current inductor, LN x For the main line Nx high frequency and high current inductor, C i+1 is the i+1th branch safety capacitor, LL iFor the main line Li high frequency and high current inductor, LN i Ni is the high-frequency and high-current inductor of the main circuit, and i is a natural number greater than 1 and less than x-1.

[0070] A further technical solution is that: the rated input impedance circuit resistor R1 has a value range of 0-50 ohms, and when the resistance value is 0 ohms, the isolation effect is best; as the resistance value increases, the isolation effect gradually decreases; the maximum allowed resistance value is 50 ohms; the rated input impedance circuit resistor R1 is a chip resistor with good high-frequency performance.

[0071] A further technical solution is that the rated output impedance circuit resistor R3 has a value range of 25-50 ohms. When the resistance is 0 ohms, the isolation effect is the best, but it will affect the performance of the carrier module under test, so it is not recommended. Therefore, the optimal value range is 25-50 ohms. The rated input impedance circuit resistor R3 is a chip resistor with good high-frequency performance.

[0072] A further technical solution is that as the operating frequency increases, the characteristics of the LL (1﹍x), LN (1﹍x), C1 and Cx+1 will change accordingly, that is, there is a self-resonant frequency. When the operating frequency is higher than the self-resonant frequency, the inductor becomes capacitive and the capacitor becomes inductive. Therefore, the high-frequency and high-current inductors LL (1﹍x) and LN (1﹍x) need to have a self-resonant frequency point higher than 12MHz. In the above technical solution, the high-frequency and high-current inductors LL (1﹍x) and LN (1﹍x) are wound by double magnetic ring wires of nickel-zinc high-frequency magnetic rings and manganese-zinc low-frequency magnetic rings. The nickel-zinc high-frequency magnetic rings have low magnetic permeability and high resistivity characteristics, ensuring that the inductor still exhibits inductive properties at high frequencies. The manganese-zinc low-frequency magnetic rings have high magnetic permeability and low resistivity characteristics, ensuring the required inductance.

[0073] The technical solution is described as follows:

[0074] Example 1 Description:

[0075] like Figure 1As shown, the present invention discloses an isolation circuit applied to a power line carrier test system, the isolation circuit comprises: an x-order LC low-pass filter circuit, high-frequency and 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 to access a 220V / 50Hz power line, which contains a 100KHz-12MHz carrier signal and other high-frequency interference signals; these signals are attenuated to signals that have no effect on the carrier test system after passing through the rated input impedance circuits R1 and C1 and the x-order LC low-pass filter, while the 220V / 50Hz power line passes without loss; the rated output impedance circuits Cx+1 and Rx+1 provide rated impedance for the carrier test system. The power frequency output P2 port is connected to the power supply port of the carrier test system to provide a clean power line for the test system.

[0076] Example 2 Description:

[0077] like Figure 2 As shown, in simplified embodiment 1, the rated input impedance circuit is composed of only C1, and the isolation circuit includes: a 4th-order LC low-pass filter circuit, high-frequency and high-current inductors LL1, LN1, LL2, LN2, and a rated output impedance circuit C3 and R3.

[0078] Example 3 Description:

[0079] like Figure 3 As shown, based on the technology of embodiment 2, rated input impedance circuits R1 and C1 are added. The isolation circuit has rated input impedance and rated output impedance. Compared with embodiment 2, although the isolation performance of embodiment 3 is slightly worse, it can be applied to the carrier level communication structure.

[0080] like Figure 4 The figure shows the principle diagram of the connection of the 220V / 50Hz power line of the present embodiment 2 and embodiment 3. The branch road is disconnected from the power line. The power line is input from the power frequency input port P1 through the high frequency and high current inductors LL1, LN1, LL2, LN2 and then output from the power frequency output port P2.

[0081] like Figure 5 As shown, this is the circuit diagram of Example 2 connected to the 220V / 50Hz power line:

[0082] R in is the power line source impedance, R in The input equivalent impedance formed by the input rated impedance circuit and the 4th-order LC low-pass filter circuit is:

[0083]

[0084] Among them, Re-5 for Figure 5 Input equivalent impedance.

[0085] Isolation circuit output impedance R o-2 for:

[0086]

[0087] At this time, the attenuation value of the isolation circuit is:

[0088]

[0089] Among them, A fig5 for Figure 5 Attenuation value.

[0090] If C1=C2=C3=C, LL1=LN1=LN2=LN2=L, then the attenuation value of the isolation circuit is:

[0091]

[0092] like Figure 6 As shown, this is the circuit diagram of embodiment 3 connected to 220V / 50Hz power line:

[0093] R in is the power line source impedance, R in The input equivalent impedance formed by the input rated impedance circuit and the 4th-order LC low-pass filter circuit is:

[0094]

[0095] Among them, R e-6 for Figure 6 Input equivalent impedance.

[0096] Isolation circuit output impedance R o-3 for:

[0097]

[0098] At this time, the attenuation value of the isolation circuit is:

[0099]

[0100] Among them, A fig6 for Figure 6 Attenuation value.

[0101] If C1=C2=C3=C, LL1=LN1=LN2=LN2=L, then the attenuation value of the isolation circuit is:

[0102]

[0103] like Figure 7 As shown in the figure, it is the simulation result of amplitude-frequency characteristic. Figure 5 The example is simulated, R in is 50 ohms, R1 is 0 ohms, R3 is 50 ohms, C1=C2=C3=220nF, LL1=LN1=LN2=LN2=470uH. It can be seen that the attenuation of the isolation circuit is about 76dB at 100KHz. As the signal frequency increases, the attenuation value also increases.

[0104] like Figure 8 As shown in the figure, it is the simulation result of amplitude-frequency characteristic. Figure 6 The example is simulated, R in is 50 ohms, R1=R3 is 50 ohms, C1=C2=C3=220nF, LL1=LN1=LN2=LN2=470uH, it can be seen that the attenuation of the isolation circuit at 100KHz is about 65dB, compared Figure 5 , the attenuation performance of Example 3 is 11 dB lower than that of Example 2. This result is consistent with the fact that the isolation performance is best when R1 is 0 ohms as mentioned in the above technical solution.

[0105] like Fig. 9 As shown, the simulation of Example 2 and Example 3 under 220V / 50Hz power line input shows that the 220V / 50Hz power line can pass through Example 2 and Example 3 without distortion. Similarly, it can also pass through Example 1 without distortion.

[0106] After this application was run confidentially for a period of time, the on-site technicians reported that the benefits were:

[0107] First, the isolation effect is good. Through actual testing, the isolator can achieve lossless passage of 220V / 10A power lines, and the signal attenuation in the 100KHz-12MHz frequency band can reach 75dB or more, meeting the isolation requirements of the carrier test system.

[0108] Second, among the above x+1 branches, excluding the 1st branch and the x+1th branch, the capacitor of the middle x-2 branch is directly connected to the two main branches, without the need for series resistors, thus reducing costs.

[0109] Third, it does not affect the performance of the carrier test system in testing the carrier module.

Claims

1. An isolation circuit for a power line carrier test system, characterized in that: The invention comprises an inductor filter branch, a rated input impedance branch and a rated output impedance branch, wherein the inductor filter branch is composed of two L-line inductor filter branches and an N-line inductor filter branch with the same structure, the rated input impedance branch is connected between the input end of the L-line inductor filter branch and the input end of the N-line inductor filter branch, and the rated output impedance branch is connected between the output end of the L-line inductor filter branch and the output end of the N-line inductor filter branch; the L-line inductor filter branch comprises the first to X-th inductors LL1-LLX of the L-line, and the N-line inductor filter branch comprises the N-line The invention also includes first to Xth inductors LN1-LNX, wherein the serial number X is an integer greater than 1, the first to Xth inductors LL1-LLX of the L line are connected in sequence according to the serial number, and the first to Xth inductors LN1-LNX of the N line are connected in sequence according to the serial number; and further includes a capacitor filtering branch, wherein the capacitor filtering branch includes X-1 capacitors, which are respectively the second to Xth capacitors C2-CX with the same structure, and the Xth capacitor CX is connected between the connection point of the X-1th inductor LLX-1 of the L line and the Xth inductor LLX of the L line and the connection point of the X-1th inductor LNX-1 of the N line and the Xth inductor LNX of the N line.

2. The isolation circuit used in a power line carrier test system according to claim 1, characterized in that: The inductor filter branch of the L line includes a first inductor LL1 and a second inductor LL2 of the L line, the inductor filter branch of the N line includes a first inductor LN1 and a second inductor LN2 of the N line, 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 contact point 2 of the first inductor LL1 of the L line is connected to a contact point 1 of the second inductor LL2 of the L line, the contact point 1 of the first inductor LL1 of the L line is the input end of the inductor filter branch of the L line, and a contact point 2 of the second inductor LL2 of the L line is the output end of the L line. At the output end of the inductor filter branch, the contact 2 of the first inductor LN1 of the N line is connected to the contact 1 of the second inductor LN2 of the N line, the contact 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact 2 of the second inductor LN2 of the N line is the output end of the inductor filter branch of the N line, the contact 1 of the first inductor LL1 of the L line, the first capacitor C1 and the contact 1 of the first inductor LN1 of the N line are connected in sequence, and the contact 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the contact 2 of the second inductor LN2 of the N line are connected in sequence.

3. The isolation circuit used in a power line carrier test system according to claim 1, characterized in that: The inductor filter branch of the L line includes a first inductor LL1 and a second inductor LL2 of the L line, the inductor filter branch of the N line includes a first inductor LN1 and a second inductor LN2 of the N line, 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 contact point 2 of the first inductor LL1 of the L line is connected to a contact point 1 of the second inductor LL2 of the L line, the contact point 1 of the first inductor LL1 of the L line is the input end of the inductor filter branch of the L line, and a contact point 2 of the second inductor LL2 of the L line is the L The output end of the inductor filter branch of the N line, the contact point 2 of the first inductor LN1 of the N line is connected to the contact point 1 of the second inductor LN2 of the N line, the contact point 1 of the first inductor LN1 of the N line is the input end of the inductor filter branch of the N line, the contact point 2 of the second inductor LN2 of the N line is the output end of the inductor filter branch of the N line, the contact point 1 of the first inductor LL1 of the L line, the first resistor R1, the first capacitor C1 and the contact point 1 of the first inductor LN1 of the N line are connected in sequence, and the contact point 2 of the second inductor LL2 of the L line, the third resistor R3, the third capacitor C3 and the contact point 2 of the second inductor LN2 of the N line are connected in sequence.

4. The isolation circuit used in a power line carrier test system according to claim 3, characterized in that: The first resistor R1 is a resistor with a value range of 0 ohm to 50 ohms, and the first resistor R1 is a chip resistor.

5. The isolation circuit used in a power line carrier test system according to claim 4, characterized in that: The first resistor R1 is a resistor of 0 ohm.

6. The isolation circuit used in a power line carrier test system according to claim 2 or 3, characterized in that: The third resistor R3 is a resistor with a value range of 25 ohms to 50 ohms, and the third resistor R3 is a chip resistor.

7. The isolation circuit used in a power line carrier test system according to claim 1, characterized in that: The rated input impedance branch includes a first resistor R1 and a first capacitor C1, and the first resistor R1 is connected to the first capacitor C1.

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