A noise separator

Abstract

The embodiment of the specification provides a noise separator, in which, when the noise of an input signal passes through a primary coil of a transformer at the same time, 1 / 2 firewire noise and 1 / 2 zero wire noise are superimposed at the center of the primary coil, mutual cancellation of differential mode noise can be realized, and common mode noise can be extracted from a common mode noise output end; in addition, the firewire noise can pass through the transformer to generate 1 / 2 firewire noise on a secondary coil, the zero wire noise can pass through the transformer to generate -1 / 2 zero wire noise on the secondary coil, at this time, the common mode noise cancels each other, the differential mode noise can be extracted at the secondary coil, and separation and extraction of the common mode noise and the differential mode noise are realized.

Description

Technical Field

[0001] This specification relates to the field of signal processing technology, specifically to noise separation circuits in the field of signal processing technology, and more specifically to a noise separator. Background Technology

[0002] In engineering applications, various electronic components may generate conducted EMI (Electromagnetic Interference) noise during operation. For example, the switching transistors of power converters and digital chips inside PCBs will generate conducted EMI noise. Conducted EMI noise may affect the level of electromagnetic interference in the environment and negatively impact the performance of some electronic components.

[0003] Therefore, EMC (Electromagnetic Compatibility) testing of electronic components to assess their resistance to electromagnetic interference in the environment is of great significance. Currently, EMC testing cannot measure the immunity of electronic components to different types of EMI noise. Utility Model Content

[0004] This specification provides a noise separator to extract common-mode noise and differential-mode noise from noise, so as to evaluate the anti-interference ability of electronic components against common-mode noise and differential-mode noise in EMC testing.

[0005] To achieve the above technical objectives, the embodiments of this specification provide the following technical solutions:

[0006] In one aspect, one embodiment of this specification provides a noise separator, comprising: a transformer, a differential-mode choke, a common-mode choke, and a path adjustment switch; wherein...

[0007] The transformer includes a primary coil and a secondary coil. The center tap of the primary coil is the common-mode noise output terminal, and the secondary coil is used to output differential-mode noise.

[0008] One end of the path adjustment switch is connected to the signal input terminal, and the other end is connected to the primary coil. The path adjustment switch includes a first state and a second state. When the path adjustment switch is in the first state, the path adjustment switch directly connects the signal input terminal to the primary coil. When the path adjustment switch is in the second state, the path adjustment switch connects the differential mode choke between the signal input terminal and the primary coil.

[0009] The common-mode choke is connected to the secondary coil.

[0010] Optionally, the path adjustment switch includes: a first switch, a second switch, a third switch, and a fourth switch; wherein,

[0011] When the first switch and the fourth switch are in the closed state, and the second switch and the third switch are in the open state, the circuit regulating switch is in the first state;

[0012] When the second switch and the fourth switch are in the open state, and when the second switch and the third switch are in the closed state, the circuit regulating switch is in the second state.

[0013] Optionally, the differential mode choke includes a first choke and a second choke;

[0014] One end of the first switch is connected to the signal input terminal, and the other end is connected to the first tap of the primary coil;

[0015] One end of the fourth switch is connected to the signal input terminal, and the other end is connected to the second tap of the primary coil;

[0016] One end of the second switch is connected to the signal input terminal, and the other end is connected to one end of the first choke coil. The end of the first choke coil away from the second switch is connected to the first tap of the primary coil.

[0017] One end of the third switch is connected to the signal input terminal, and the other end is connected to one end of the second choke coil. The end of the second choke coil away from the third switch is connected to the second tap of the primary coil.

[0018] Optionally, the transformer includes a radio frequency transformer, and a distributed capacitance is provided between the primary coil and the secondary coil.

[0019] Optionally, the radio frequency transformer includes a 2:1 radio frequency transformer.

[0020] Optionally, it may also include: a first resistor;

[0021] One end of the first resistor is connected to the center tap of the primary coil, and the other end is grounded.

[0022] Optionally, the resistance value of the first resistor may be 50Ω ± 5Ω.

[0023] Optionally, the common-mode choke includes: a third choke and a fourth choke; wherein,

[0024] One end of the third choke coil is connected to the first tap of the secondary coil, and the other end is grounded;

[0025] One end of the fourth choke coil is connected to the second tap of the secondary coil, and the other end is grounded.

[0026] Optionally, it may also include: a second resistor;

[0027] The first end of the second resistor is connected to the end of the third choke coil away from the secondary coil, the second end of the second resistor is connected to the end of the fourth choke coil away from the secondary coil, and the second end is grounded.

[0028] Optionally, the resistance value of the second resistor includes 50Ω ± 5Ω.

[0029] As can be seen from the above technical solutions, in the noise separator provided in the embodiments of this specification, when the noise of the input signal (for example, it may include live wire noise and neutral wire noise) passes through the primary coil of the transformer at the same time, 1 / 2 live wire noise and 1 / 2 neutral wire noise are superimposed at the center of the primary coil, which can realize the mutual cancellation of differential mode noise, and the common mode noise can be extracted from the common mode noise output terminal; in addition, the live wire noise can generate 1 / 2 live wire noise on the secondary coil through the transformer, and the neutral wire noise can generate -1 / 2 neutral wire noise on the secondary coil through the transformer. At this time, the common mode noise cancels each other out, and the differential mode noise can be extracted at the secondary coil, realizing the separation and extraction of common mode noise and differential mode noise. Furthermore, to improve the noise separation performance of the noise separator, when extracting differential mode noise, the path adjustment switch can be in the first state, using a common mode choke to suppress common mode noise at the secondary coil; when extracting common mode noise, the path adjustment switch can be in the second state, connecting the differential mode choke to the circuit, so that the input signal is suppressed by the differential mode choke before being input into the noise separator, thereby improving the noise separation performance of the noise separator. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this specification. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 A schematic diagram of the circuit structure of the noise separator provided for the embodiments of this specification.

[0032] Explanation of reference numerals in the attached figures:

[0033] 10-Circuit regulating switch; 11-Differential mode choke; 12-Common mode choke;

[0034] T - Transformer; C - Distributed capacitance; R1 - First resistor; R2 - Second resistor; S1 - First switch; S2 - Second switch; S3 - Third switch; S4 - Fourth switch; U L - Fire wire input terminal; U N - Neutral input terminal; L1 - First choke; L2 - Second choke; L3 - Third choke; L4 - Fourth choke. Detailed Implementation

[0035] Unless otherwise defined, the technical or scientific terms used in the embodiments of this specification shall have the ordinary meaning understood by one of ordinary skill in the art to which this specification pertains. The terms "first," "second," and similar terms used in the embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to avoid confusion of constituent elements.

[0036] Unless the context otherwise requires, throughout this specification, "a plurality of" means "at least two," and "including" is interpreted as open-ended or encompassing, that is, "including, but not limited to." In the description of this specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this specification. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example.

[0037] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0038] Overview

[0039] In traditional EMC testing, linear impedance stabilization networks are typically used to extract noise. However, these networks actually measure a mixture of common-mode and differential-mode noise, and cannot separate and extract specific differential-mode and common-mode noise.

[0040] To solve this problem, the inventors discovered that a transformer can be used to extract common-mode noise and differential-mode noise. Specifically, when the input signal is input to the transformer, the live wire noise and the neutral wire noise flow through the primary coil of the transformer simultaneously. At the center tap of the primary coil, half of the live wire noise and half of the neutral wire noise can be added together. At this time, the differential-mode noise cancels out, achieving the goal of retaining only the common-mode noise. Refer to formula (1) for details:

[0041] Among them, I L Indicates live wire noise, I N Indicates zero-line noise, I 中心 I represents the noise at the center tap of the primary coil. CM This represents common-mode noise.

[0042] Similarly, when live wire noise passes through the transformer, it generates 1 / 2 live wire noise on the secondary coil; at the same time, when neutral wire noise passes through the transformer, it generates -1 / 2 neutral wire noise on the secondary coil. At this point, the common-mode noise cancels out at the secondary coil, leaving only differential-mode noise. Therefore, differential-mode noise can be extracted at the secondary coil. See formula (2) for details:

[0043] Among them, I 次级线圈 I represents the noise at the secondary coil. DM This represents differential mode noise.

[0044] However, when using only transformers to extract common-mode and differential-mode noise, situations may arise where common-mode noise is introduced into the extracted differential-mode noise, and vice versa. For example, due to the potential for distributed capacitance between the primary and secondary coils of the transformer, common-mode noise may flow into the secondary coil through this capacitance, resulting in common-mode noise being mixed with the differential-mode noise extracted at the secondary coil. Another example is that under high-frequency conditions, the output of differential-mode noise at the center tap may not be zero due to the influence of parameters such as transmission lines, leading to differential-mode noise being mixed with the common-mode noise extracted at the center tap of the primary coil. To address this issue, a common-mode choke can be added to the secondary coil to suppress common-mode noise caused by distributed capacitance, while a differential-mode choke can be added to the primary coil to suppress differential-mode noise at the center tap, thus improving the performance of the noise separator. In addition, to avoid the adverse effects of the differential-mode choke on differential-mode noise extraction, a path adjustment switch is introduced into the noise separator. When extracting differential-mode noise, the path adjustment switch can be in the first state, in which case the differential-mode choke is not introduced into the circuit, thus avoiding its influence on differential-mode noise extraction. At the same time, the common-mode choke is used to suppress common-mode noise at the secondary coil, achieving accurate extraction of differential-mode noise. When extracting common-mode noise, the path adjustment switch can be in the second state, connecting the differential-mode choke into the circuit. This allows the input signal to be suppressed by the differential-mode choke before being input into the noise separator, thereby improving the noise separation performance of the noise separator.

[0045] Based on the above concept, this specification provides a noise separator. The noise separator provided in this specification will be described exemplarily below with reference to the accompanying drawings.

[0046] Exemplary noise separator

[0047] This specification provides a noise separator, such as... Figure 1 As shown, it includes: a transformer T, a differential mode choke 11, a common mode choke 12, and a path regulating switch 10; wherein,

[0048] The transformer T includes a primary coil and a secondary coil. The center tap of the primary coil is the common-mode noise output terminal, and the secondary coil is used to output differential-mode noise.

[0049] One end of the path adjustment switch 10 is connected to the signal input terminal, and the other end is connected to the primary coil. The path adjustment switch 10 includes a first state and a second state. When the path adjustment switch 10 is in the first state, the path adjustment switch 10 directly connects the signal input terminal to the primary coil. When the path adjustment switch 10 is in the second state, the path adjustment switch 10 connects the differential mode choke 11 between the signal input terminal and the primary coil.

[0050] The common-mode choke 12 is connected to the secondary coil.

[0051] In this embodiment, transformer T is used to extract common-mode noise and differential-mode noise. Specifically, when the input signal is input to transformer T, the live wire noise and the neutral wire noise flow through the primary coil of transformer T simultaneously. At the center tap of the primary coil, half of the live wire noise and half of the neutral wire noise can be added together. At this time, the differential-mode noise cancels out, achieving the goal of retaining only the common-mode noise. Refer to formula (1) for details:

[0052] Among them, I L Indicates live wire noise, I N Indicates zero-line noise, I 中心 I represents the noise at the center tap of the primary coil. CM This represents common-mode noise.

[0053] Similarly, when live wire noise passes through transformer T, it generates 1 / 2 live wire noise on the secondary coil; at the same time, when neutral wire noise passes through transformer T, it generates -1 / 2 neutral wire noise on the secondary coil. At this time, the common-mode noise cancels each other out at the secondary coil, leaving only the differential-mode noise. Therefore, the differential-mode noise can be extracted at the secondary coil. Refer to formula (2) for details:

[0054] Among them, I 次级线圈 I represents the noise at the secondary coil. DM This represents differential mode noise.

[0055] However, when using only transformer T to extract common-mode and differential-mode noise, common-mode noise may be introduced into the extracted differential-mode noise, and vice versa. For example, due to the possible distributed capacitance C between the primary and secondary coils of transformer T, common-mode noise may flow into the secondary coil through this capacitance C, resulting in common-mode noise being mixed with the differential-mode noise extracted at the secondary coil. Another example is that under high-frequency conditions, the output of differential-mode noise at the center tap may not be zero due to the influence of transmission line parameters, thus causing differential-mode noise to be mixed with the common-mode noise extracted at the center tap of the primary coil. To solve this problem, a common-mode choke 12 can be added to the secondary coil to suppress common-mode noise caused by the distributed capacitance C, and a differential-mode choke 11 can be added to the primary coil to suppress differential-mode noise at the center tap of the primary coil, thereby improving the performance of the noise separator. In addition, to avoid the adverse effects of the differential-mode choke 11 on differential-mode noise extraction, a path adjustment switch 10 is introduced into the noise separator. When extracting differential-mode noise, the path adjustment switch 10 can be in the first state, in which case the differential-mode choke 11 is not connected to the circuit, avoiding its influence on differential-mode noise extraction. Simultaneously, the common-mode choke 12 is used to suppress common-mode noise at the secondary coil, achieving accurate differential-mode noise extraction. When extracting common-mode noise, the path adjustment switch 10 can be in the second state, connecting the differential-mode choke 11 to the circuit. This allows the input signal to pass through the differential-mode choke 11 to suppress differential-mode noise before being input to the noise separator, thus improving the noise separation performance of the noise separator. Figure 1 In this context, the signal input terminal may specifically include the live wire input terminal U. L and neutral input terminal U N , Figure 1 In this context, GND represents ground.

[0056] Optionally, in one embodiment of this specification, reference is still made to... Figure 1 The path adjustment switch 10 includes: a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4; wherein,

[0057] When the first switch S1 and the fourth switch S4 are in the closed state, and the second switch S2 and the third switch S3 are in the open state, the passage regulating switch 10 is in the first state;

[0058] When the second switch S2 and the fourth switch S4 are in the open state, and the second switch S2 and the third switch S3 are in the closed state, the path regulating switch 10 is in the second state.

[0059] The first switch S1 to the fourth switch S4 can be a combination of different types of switches, such as a combination of single-pole single-throw switches or a combination of single-pole double-throw switches. In addition, the first switch S1 to the fourth switch S4 can also be other types of electronic components with on / off control functions. This specification does not limit this, and it depends on the actual situation.

[0060] Optionally, in one embodiment, the differential mode choke 11 includes a first choke L1 and a second choke L2;

[0061] One end of the first switch S1 is connected to the signal input terminal, and the other end is connected to the first tap of the primary coil;

[0062] One end of the fourth switch S4 is connected to the signal input terminal, and the other end is connected to the second tap of the primary coil;

[0063] One end of the second switch S2 is connected to the signal input terminal, and the other end is connected to one end of the first choke coil L1. The end of the first choke coil L1 away from the second switch S2 is connected to the first tap of the primary coil.

[0064] One end of the third switch S3 is connected to the signal input terminal, and the other end is connected to one end of the second choke coil L2. The end of the second choke coil L2 away from the third switch S3 is connected to the second tap of the primary coil.

[0065] Specifically, one end of the first switch S1 can be connected to the live wire input terminal U in the signal input terminal. L One end of the fourth switch S4 is connected to the first tap of the primary coil, and the other end is connected to the first tap of the primary coil. One end of the fourth switch S4 can be connected to the neutral input terminal U in the signal input terminal. N One end is connected to the other end, which is connected to the second tap of the primary coil.

[0066] In this embodiment, a feasible structure of the path regulating switch 10 and the connection method of the path regulating switch 10 with other components are provided. In this embodiment, the structure of the path regulating switch 10 is simple and easy to implement, which ensures the miniaturization and simplification of the overall noise separator.

[0067] In one embodiment, the transformer T includes a radio frequency transformer T, and a distributed capacitance C is provided between the primary coil and the secondary coil.

[0068] Optionally, the radio frequency transformer T includes a 2:1 radio frequency transformer T.

[0069] Optionally, in one embodiment, the noise separator further includes: a first resistor R1;

[0070] One end of the first resistor R1 is connected to the center tap of the primary coil, and the other end is grounded.

[0071] In this embodiment, impedance matching of the overall circuit can be achieved by configuring a first resistor R1. Optionally, the resistance value of the first resistor R1 includes 50Ω ± 5Ω. For example, the value of the first resistor R1 can be 45Ω, 50Ω, or 55Ω. This specification does not limit this value and the specific value depends on the actual situation.

[0072] Optionally, in one embodiment, the common-mode choke 12 includes: a third choke L3 and a fourth choke L4; wherein,

[0073] One end of the third choke coil L3 is connected to the first tap of the secondary coil, and the other end is grounded;

[0074] One end of the fourth choke coil L4 is connected to the second tap of the secondary coil, and the other end is grounded.

[0075] Optionally, the noise separator further includes: a second resistor R2;

[0076] The first end of the second resistor R2 is connected to the end of the third choke L3 away from the secondary coil, and the second end of the second resistor R2 is connected to the end of the fourth choke L4 away from the secondary coil, and the second end is grounded.

[0077] In this embodiment, impedance matching of the overall circuit can be achieved by configuring a second resistor R2. Optionally, the resistance value of the second resistor R2 includes 50Ω ± 5Ω. For example, the value of the second resistor R2 can be 45Ω, 50Ω, or 55Ω. This specification does not limit this value and the specific value depends on the actual situation.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementation methods outlined in this specification. While the descriptions are specific and detailed, they should not be construed as limiting the scope of the solutions provided in this specification. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this specification, and these all fall within the scope of protection of this specification. Therefore, the scope of protection for this patent should be determined by the appended claims.

Claims

1. A noise separator, characterized by, include: Transformer, differential mode choke, common mode choke, and circuit regulating switch; among which, The transformer includes a primary coil and a secondary coil. The center tap of the primary coil is the common-mode noise output terminal, and the secondary coil is used to output differential-mode noise. One end of the path adjustment switch is connected to the signal input terminal, and the other end is connected to the primary coil. The path adjustment switch includes a first state and a second state. When the path adjustment switch is in the first state, the path adjustment switch directly connects the signal input terminal to the primary coil. When the path adjustment switch is in the second state, the path adjustment switch connects the differential mode choke between the signal input terminal and the primary coil. The common-mode choke is connected to the secondary coil.

2. The noise separator of claim 1, wherein The path adjustment switch includes: a first switch, a second switch, a third switch, and a fourth switch; wherein, When the first switch and the fourth switch are in the closed state, and the second switch and the third switch are in the open state, the circuit regulating switch is in the first state; When the second switch and the fourth switch are in the open state, and when the second switch and the third switch are in the closed state, the circuit regulating switch is in the second state.

3. The noise separator of claim 2, wherein, The differential mode choke includes a first choke and a second choke; One end of the first switch is connected to the signal input terminal, and the other end is connected to the first tap of the primary coil; One end of the fourth switch is connected to the signal input terminal, and the other end is connected to the second tap of the primary coil; One end of the second switch is connected to the signal input terminal, and the other end is connected to one end of the first choke coil. The end of the first choke coil away from the second switch is connected to the first tap of the primary coil. One end of the third switch is connected to the signal input terminal, and the other end is connected to one end of the second choke coil. The end of the second choke coil away from the third switch is connected to the second tap of the primary coil.

4. The noise separator of claim 1, wherein, The transformer includes a radio frequency transformer, and a distributed capacitance is provided between the primary coil and the secondary coil.

5. The noise separator of claim 4, wherein, The radio frequency transformer includes a 2:1 radio frequency transformer.

6. The noise separator of claim 1, wherein Also includes: First resistor; One end of the first resistor is connected to the center tap of the primary coil, and the other end is grounded.

7. The noise separator of claim 6, wherein, The resistance value of the first resistor is 50Ω ± 5Ω.

8. The noise separator of claim 1, wherein, The common-mode choke includes: a third choke and a fourth choke; wherein, One end of the third choke coil is connected to the first tap of the secondary coil, and the other end is grounded; One end of the fourth choke coil is connected to the second tap of the secondary coil, and the other end is grounded.

9. The noise separator of claim 8, wherein, Also includes: Second resistor; The first end of the second resistor is connected to the end of the third choke coil away from the secondary coil, the second end of the second resistor is connected to the end of the fourth choke coil away from the secondary coil, and the second end is grounded.

10. The noise separator of claim 9, wherein, The resistance value of the second resistor is 50Ω ± 5Ω.

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