Three-phase common-mode noise separation experiment box

Abstract

The utility model discloses a three-phase common-mode noise separation experiment box, which comprises a box body, a detection wiring terminal group arranged on the outer side of the front surface of the box body, a power supply wiring terminal group arranged on the outer side of the back surface of the box body, a signal connection terminal arranged on the outer side of the front surface of the box body, and a three-phase common-mode noise separation system arranged in the box body. According to the technical scheme, the three-phase common-mode noise separation experiment box is internally provided with the three-phase common-mode noise separation system, the system collects interference signals of a tested device powered by three phases through the line impedance stabilization network, and the collected interference signals comprise a common-mode component and a differential-mode component; and then short-circuit processing is performed on each path of interference signal to filter the differential-mode component of each path of interference signal, only the common-mode component of the detected equipment during normal work is extracted, a transformer does not need to be introduced, parasitic parameters are reduced, the detection accuracy of the common-mode interference of the detected equipment can be improved, and the detection efficiency is improved. Related personnel can conveniently obtain accurate experiment results in the experiment process.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits and electromagnetic compatibility, and more specifically to a three-phase common mode noise separation experimental box. Background Art

[0002] In the teaching activities of electromagnetic compatibility technology, it is necessary to teach students electromagnetic compatibility experiments. In the field of EMC electromagnetic compatibility measurement and diagnosis, the relevant measurement process of three-phase electrical equipment requires accurate detection of its electromagnetic common mode components. In the prior art, the common mode component detection process of three-phase power supply equipment is implemented in the experimental process as follows: first, the three-wire or four-wire signal is sampled, and then the collected signal is transmitted to the filter network, and finally the differential mode component and the common mode component are extracted. The defect of the current measurement method in the experimental process is that when the collected signal is introduced into the filter network, the filter network will attenuate the collected signal. In addition, due to the parasitic parameters and resonance points of the filter network itself, the detection accuracy is reduced, so it is difficult for relevant personnel to obtain accurate results when conducting experiments. Utility Model Content

[0003] In order to solve one or more of the above technical problems, the purpose of the utility model is to provide a three-phase common mode noise separation test box.

[0004] The technical solution adopted by the utility model to solve the problem is:

[0005] A three-phase common-mode noise separation test box, comprising a box body, a detection terminal group is installed on the outer side of the front of the box body, a power terminal group is installed on the outer side of the back of the box body, the detection terminal group and the power terminal group are both provided with a plurality of terminals, a signal connection terminal for connecting an EMI measurement receiver is also installed on the outer side of the front of the box body, a three-phase common-mode noise separation system is installed inside the box body, the three-phase common-mode noise separation system comprises a line impedance stabilization network and a matching resistor RA, the line impedance stabilization network comprises a plurality of sampling branches, the sampling branches comprise a filter capacitor C1, a coupling capacitor C2, a decoupling inductor L1 and a short-circuit port, and the number of the sampling branches, the number of the terminals of the detection terminal group and the number of the terminals of the power terminal group are consistent;

[0006] One end of the filter capacitor C1 is connected to the ground, the other end of the filter capacitor C1 is connected to the wiring terminal of the power wiring terminal group, and is also connected to one end of the decoupling inductor L1, the other end of the decoupling inductor L1 is connected to the wiring terminal of the detection wiring terminal group, and is also connected to one end of the coupling capacitor C2, and the other end of the coupling capacitor C2 is connected to the short-circuit port;

[0007] When measuring common mode noise, the short-circuited ports of the sampling branches are connected together and connected to the ground terminal and the signal connection terminal through the matching resistor RA;

[0008] When the three-phase common-mode noise separation system is applied to a three-phase three-wire device under test, the line impedance stabilization network is configured with three sampling branches; when the three-phase common-mode noise separation system is applied to a three-phase four-wire device under test, the line impedance stabilization network is configured with four sampling branches.

[0009] As a further improvement of the above technical solution, when the three-phase common-mode noise separation system is applied to a three-phase three-wire device under test, the capacitance value of the filter capacitor C1 is 8μF, the capacitance value of the coupling capacitor C2 is 0.47μF, the inductance value of the decoupling inductor L1 is 50μH, and the resistance value of the matching resistor RA is 16.67Ω or 14.5Ω; when the three-phase common-mode noise separation system is applied to a three-phase four-wire device under test, the capacitance value of the filter capacitor C1 is 8μF, the capacitance value of the coupling capacitor C2 is 0.47μF, the inductance value of the decoupling inductor L1 is 50μH, and the resistance value of the matching resistor RA is 12.5Ω or 14.5Ω.

[0010] As a further improvement of the above technical solution, the filter capacitor C1 of each sampling branch is installed on the inner side of the back side of the box.

[0011] As a further improvement of the above technical solution, the three-phase common-mode noise separation system also includes multiple first switching devices and one second switching device, the number of the first switching devices is consistent with the number of the sampling branches, the first switching device is arranged between the coupling capacitor C2 and the short-circuit port, and the second switching device is arranged between the short-circuit port and the matching resistor RA.

[0012] As a further improvement of the above technical solution, the first switch device and the second switch device form a switch component, and the switch component is defined as a measurement channel selection switch. The measurement channel selection switch is installed on the front outer side of the box.

[0013] As a further improvement of the above technical solution, a ground wire connection terminal is installed on the front outer side and / or the back outer side of the box body.

[0014] As a further improvement of the above technical solution, two opposite sides of the box body are respectively provided with a plurality of ventilation holes of the same shape and size.

[0015] The beneficial effect of the utility model is as follows: the three-phase common-mode noise separation test box disclosed by the technical scheme has a three-phase common-mode noise separation system installed inside, which uses a line impedance stabilization network to collect various interference signals from the three-phase powered device under test. At this time, the collected interference signals include common-mode components and differential-mode components, and then each interference signal is short-circuited to filter out the differential-mode components of each interference signal, and only the common-mode components of the device under test when working normally are extracted. This process does not require the introduction of a transformer, reduces parasitic parameters, and can effectively improve the detection accuracy of the common-mode interference of the device under test, making it convenient for relevant personnel to obtain accurate experimental results during the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The utility model is further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0017] Figure 1 It is a stereogram of the first viewing angle of the experimental box in the utility model;

[0018] Figure 2 It is a stereogram of the experimental box in the utility model from a second viewing angle;

[0019] Figure 3 It is a top view of the experimental box in the utility model;

[0020] Figure 4 It is a circuit diagram of a three-phase common-mode noise system in the utility model.

[0021] Description of reference numerals:

[0022] 100-box, 200-power terminal group, 300-detection terminal group, 400-decoupling inductor L1, 500-filter capacitor C1, 600-short-circuit port, 700-measurement channel selection switch, 710-first switch device, 720-second switch device, 800-ground connection terminal, 900-signal connection terminal. DETAILED DESCRIPTION

[0023] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0024] In the description of the present invention, it should be understood that the descriptions involving orientations, such as up, down, front, back, left, right, etc., and the orientations or positional relationships indicated are based on the orientations or positional relationships described in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] In the description of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0026] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0027] Reference Figures 1 to 4 The present application discloses a three-phase common-mode noise separation test box, a first embodiment of which comprises a box body, a detection terminal group is installed on the outer side of the front of the box body, the detection terminal group is used to connect the device under test, a power terminal group is installed on the outer side of the back of the box body, the power terminal group is used to connect the three-phase power supply, the detection terminal group and the power terminal group are both provided with a plurality of terminals, a signal connection terminal for connecting an EMI measurement receiver is also installed on the outer side of the front of the box body, a three-phase common-mode noise separation system is installed inside the box body, the three-phase common-mode noise separation system comprises a line impedance stabilization network and a matching resistor RA, the line impedance stabilization network comprises a plurality of sampling branches, the sampling branches comprise a filter capacitor C1, a coupling capacitor C2, a decoupling inductor L1 and a short-circuit port, the number of the sampling branches, the number of the terminals of the detection terminal group and the number of the terminals of the power terminal group are consistent;

[0028] One end of the filter capacitor C1 is connected to the ground, the other end of the filter capacitor C1 is connected to the wiring terminal of the power wiring terminal group, and is also connected to one end of the decoupling inductor L1, the other end of the decoupling inductor L1 is connected to the wiring terminal of the detection wiring terminal group, and is also connected to one end of the coupling capacitor C2, and the other end of the coupling capacitor C2 is connected to the short-circuit port;

[0029] When measuring common mode noise, the short-circuited ports of the sampling branches are connected together and connected to the ground terminal and the signal connection terminal through the matching resistor RA;

[0030] When the three-phase common-mode noise separation system is applied to a three-phase three-wire device under test, the line impedance stabilization network is configured with three sampling branches; when the three-phase common-mode noise separation system is applied to a three-phase four-wire device under test, the line impedance stabilization network is configured with four sampling branches.

[0031] Specifically, in the present embodiment, a three-phase common-mode noise separation system is installed inside a three-phase common-mode noise separation test box. The system utilizes a line impedance stabilization network to collect various interference signals from a three-phase powered device under test. At this time, the collected interference signals include common-mode components and differential-mode components. Each interference signal is then short-circuited to filter out the differential-mode components of each interference signal, and only the common-mode components of the device under test when it is working normally are extracted. This process does not require the introduction of a transformer, reduces parasitic parameters, and can effectively improve the detection accuracy of common-mode interference of the device under test, making it easier for relevant personnel to obtain accurate experimental results during the experiment.

[0032] Further as a preferred implementation, in this embodiment, when the three-phase common-mode noise separation system is applied to a three-phase three-wire device under test, the capacitance value of the filter capacitor C1 is 8μF, the capacitance value of the coupling capacitor C2 is 0.47μF, the inductance value of the decoupling inductor L1 is 50μH, and the resistance value of the matching resistor RA is 16.67Ω or 14.5Ω; when the three-phase common-mode noise separation system is applied to a three-phase four-wire device under test, the capacitance value of the filter capacitor C1 is 8μF, the capacitance value of the coupling capacitor C2 is 0.47μF, the inductance value of the decoupling inductor L1 is 50μH, and the resistance value of the matching resistor RA is 12.5Ω or 14.5Ω.

[0033] As a further preferred implementation, in this embodiment, the filter capacitor C1 of each sampling branch is installed on the inner side of the back of the box. Specifically, the capacitance of the filter capacitor C1 in this embodiment is relatively large, so the volume of the filter capacitor C1 in actual application is also relatively large, so it is difficult to ensure the fixity of the filter capacitor C1 when it is set on the circuit board. Therefore, in this embodiment, the inner side of each filter capacitor C1 can effectively avoid the above situation.

[0034] Further as a preferred implementation, in this embodiment, the three-phase common-mode noise separation system also includes a plurality of first switching devices and a second switching device, the number of the first switching devices is consistent with the number of the sampling branches, the first switching device is arranged between the coupling capacitor C2 and the short-circuit port, and the second switching device is arranged between the short-circuit port and the matching resistor RA.

[0035] Preferably, in this embodiment, the first switch device and the second switch device form a switch component, and the switch component is defined as a measurement channel selection switch, and the measurement channel selection switch is installed on the front outer side of the box.

[0036] As a further preferred implementation, in this embodiment, a ground wire connection terminal is installed on the front outer side and / or the back outer side of the box.

[0037] As a further preferred embodiment, in this embodiment, two opposite sides of the box are respectively provided with a plurality of ventilation holes of the same shape and size. In this preferred embodiment, the plurality of ventilation holes are in the shape of a long rectangular strip, and the provision of the ventilation holes can effectively enhance the air convection in the box, and effectively improve the heat dissipation efficiency of related components.

[0038] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention specification and drawings under the utility model concept, or directly or indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A three-phase common mode noise separation test box, characterized in that: It comprises a box body, a detection terminal group is installed on the outer side of the front side of the box body, a power terminal group is installed on the outer side of the back side of the box body, the detection terminal group and the power terminal group are both provided with a plurality of terminals, a signal connection terminal for connecting an EMI measurement receiver is also installed on the outer side of the front side of the box body, a three-phase common-mode noise separation system is installed inside the box body, the three-phase common-mode noise separation system comprises a line impedance stabilization network and a matching resistor RA, the line impedance stabilization network comprises a plurality of sampling branches, the sampling branches comprise a filter capacitor C1, a coupling capacitor C2, a decoupling inductor L1 and a short-circuit port, and the number of the sampling branches, the number of the terminals of the detection terminal group and the number of the terminals of the power terminal group are consistent; One end of the filter capacitor C1 is connected to the ground, the other end of the filter capacitor C1 is connected to the wiring terminal of the power wiring terminal group, and is also connected to one end of the decoupling inductor L1, the other end of the decoupling inductor L1 is connected to the wiring terminal of the detection wiring terminal group, and is also connected to one end of the coupling capacitor C2, and the other end of the coupling capacitor C2 is connected to the short-circuit port; The short-circuited ports of the sampling branches are connected together, and connected to the ground terminal and the signal connection terminal through the matching resistor RA; When the three-phase common-mode noise separation system is applied to a three-phase three-wire device under test, the line impedance stabilization network is configured with three sampling branches; when the three-phase common-mode noise separation system is applied to a three-phase four-wire device under test, the line impedance stabilization network is configured with four sampling branches.

2. A three-phase common mode noise separation test box according to claim 1, characterized in that: When the three-phase common-mode noise separation system is applied to a three-phase three-wire device under test, the capacitance value of the filter capacitor C1 is 8μF, the capacitance value of the coupling capacitor C2 is 0.47μF, the inductance value of the decoupling inductor L1 is 50μH, and the resistance value of the matching resistor RA is 16.67Ω or 14.5Ω; when the three-phase common-mode noise separation system is applied to a three-phase four-wire device under test, the capacitance value of the filter capacitor C1 is 8μF, the capacitance value of the coupling capacitor C2 is 0.47μF, the inductance value of the decoupling inductor L1 is 50μH, and the resistance value of the matching resistor RA is 12.5Ω or 14.5Ω.

3. A three-phase common mode noise separation test box according to claim 2, characterized in that: The filter capacitor C1 of each sampling branch is installed on the inner side of the back side of the box.

4. The three-phase common mode noise separation test box according to claim 1, characterized in that: The three-phase common-mode noise separation system also includes multiple first switching devices and one second switching device, the number of the first switching devices is consistent with the number of the sampling branches, the first switching device is arranged between the coupling capacitor C2 and the short-circuit port, and the second switching device is arranged between the short-circuit port and the matching resistor RA.

5. The three-phase common mode noise separation test box according to claim 4, characterized in that: The first switch device and the second switch device form a switch component, and the switch component is defined as a measurement channel selection switch. The measurement channel selection switch is installed on the front outer side of the box.

6. The three-phase common mode noise separation test box according to claim 1, characterized in that: A ground wire connection terminal is installed on the outer side of the front side and / or the outer side of the back side of the box.

7. The three-phase common mode noise separation test box according to claim 1, characterized in that: Two opposite sides of the box body are respectively provided with a plurality of ventilation holes of the same shape and size.

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