Voltage distribution box for aviation power supply electromagnetic compatibility test

Abstract

The invention discloses a voltage distribution box for an electromagnetic compatibility test of an aviation power supply. The voltage distribution box comprises a metal shell, a circuit module, a connector interface and a grounding assembly, the metal shell is enclosed by a bottom plate, an upper panel, side panels, a front panel and a rear panel, the upper panel is integrated with a plurality of groups of connector interfaces, and the front panel and the rear panel are provided with binding posts; the circuit module is installed in the metal shell, a series resistance network is arranged in the circuit module, and the series resistance network converts an input voltage signal into an acquirable test signal according to a voltage distribution rule; the grounding assembly comprises two L-shaped copper supports, the L-shaped copper supports and the metal shell are fastened through screws of a rivet pulling structure, and the bottoms of the two L-shaped copper supports are welded to a darkroom test table grounding copper plate. And an interference signal is prevented from influencing the EMC test of the tested power supply system through bad grounding.

Description

Technical Field

[0001] This application relates to the field of design of auxiliary facilities and equipment for electromagnetic compatibility testing of aviation power supplies, and in particular to a voltage distribution box for electromagnetic compatibility testing of aviation power supplies. Background Technology

[0002] In the EMC testing of a certain type of civil aircraft power system, the connection relationships between the voltage distribution box, the system under test (SUT), and the monitoring and display system are as follows: Figure 3 As shown. The voltage distribution box is placed in the required location in the EMC anechoic chamber test area, connected to the wall-mounted interface board of the anechoic chamber via a coaxial cable, and then the signal is transmitted to the monitoring and display system in the EMC shielded control room via a coaxial transmission line.

[0003] The main functions of a voltage distribution box in EMC testing are threefold: first, to collect sensitive point voltage signals or communication signals of the product under test (PUT) according to voltage distribution rules; second, to transmit and convert relevant voltage or communication signals during the test, collect and monitor the actual sensitive point voltages or communication signals of the PUT or system, and determine whether the operating status of the PUT or system meets the test requirements; and third, to connect the voltage distribution box to the image recording device (Vision Recorder, i.e., monitoring and display system) in the EMC control room via a coaxial cable, for monitoring whether there are any abnormalities in the analog signal of the point of regulation (POR) voltage and related digital communication signals, especially in sensitivity testing, where it provides a good intuitive judgment of whether sensitive anomalies have occurred in the system's test items. However, in the EMC testing of the AC power system for a certain type of aircraft, there is a lack of specific tools for collecting and monitoring sensitive point voltages and determining whether the system's actual operating status meets the requirements during EMC testing. Existing voltage distribution boxes can introduce electromagnetic interference into the EMC test, affecting signal transmission. Summary of the Invention

[0004] The main purpose of this application is to provide a voltage distribution box for electromagnetic compatibility testing of aviation power supplies. It is a specialized voltage distribution box designed based on the actual needs of electromagnetic compatibility testing of the main AC power supply system of a certain type of project, so as to minimize the impact of the voltage distribution box on the system's EMC test.

[0005] To achieve the above objectives, this application provides a voltage distribution box for electromagnetic compatibility testing of aviation power supplies, comprising: The system comprises a metal housing, a circuit module, connector interfaces, and a grounding assembly. The metal housing is composed of a base plate, a top panel, side panels, a front panel, and a rear panel. The top panel integrates multiple connector interfaces, while the front and rear panels are fitted with terminals. The circuit module is installed inside the metal housing and contains a series resistor network. This series resistor network converts the input voltage signal into an acquireable test signal according to voltage distribution rules. The grounding assembly includes two L-shaped copper brackets, which are fastened to the metal housing with screws via a riveting structure. The bottoms of the two L-shaped copper brackets are welded to the grounding copper plate on the anechoic chamber test table to ensure a low-impedance connection between the metal housing and the grounding system.

[0006] Optionally, the circuit module includes an AC signal processing unit and a DC signal processing unit; The AC unit includes a 115V / 400Hz voltage divider circuit, and the DC unit includes a 28V voltage filter circuit. The AC and DC units are connected to the system under test via independent terminals.

[0007] Optionally, the connector interface includes nine sets of coaxial connectors, J1-J9. Among them, J1-J6 of the 9 coaxial connectors are used to output AC test signals of 10.45V±0.5V, and J7-J9 are used to output DC test signals of 2.55V±0.1V. The shielding layer of each of the 9 coaxial connectors is directly connected to the metal shell. All 9 coaxial connectors are connected to the EMC testing laboratory through coaxial signal transmission lines and are connected to communication monitoring equipment to monitor the voltage signals in real time.

[0008] Optionally, the overlapping surfaces of the two L-shaped copper brackets are gold-plated, and the surface roughness of the part in contact with the housing is no greater than Ra1.6μm. After assembly, the overlapping resistance between the two L-shaped copper brackets and the housing is less than 2.5mΩ.

[0009] Optionally, the AC unit includes at least one set of three-phase AC input circuits, each set of three-phase AC input circuits including three-phase lines and a neutral line; In this configuration, one end of each of the three phase lines is connected in series with a first LC filter circuit and an overcurrent protection element, and the other end of each phase line is connected through a first resistor and a coaxial connector. The output end of the coaxial connector is also connected to the neutral line and the ground line, and the input end of each coaxial connector is connected to the neutral line through a second resistor. The input end of the neutral line is connected in series with a second LC filter circuit and a ground line. The first resistor has a resistance of 1 MΩ and the second resistor has a resistance of 100 kΩ.

[0010] Optionally, the number of three-phase AC input circuits is two sets, and the coaxial connectors of the first set of three-phase AC input circuits and the second set of three-phase AC input circuits include coaxial connectors J1-J6.

[0011] Optionally, all coaxial connectors from J1 to J6 are BNC adapters.

[0012] Optionally, the AC input voltage of each of the three-phase lines is 115V.

[0013] Optionally, the DC unit includes a set of three-phase DC input circuits, each set of three-phase DC input circuits including three-phase lines and a neutral line; wherein, one end of each of the three-phase lines is connected in series with a third LC filter circuit and an overcurrent protection element, and the other end of each is connected through a third resistor and a coaxial connector, the output end of the coaxial connector is also connected to the neutral line and the ground line, and the input end of each coaxial connector is connected to the neutral line through a fourth resistor; the input end of the neutral line is connected in series with a fourth LC filter circuit and a ground line.

[0014] Optionally, the DC input voltage of the three-phase lines is 28V.

[0015] This application proposes a voltage distribution box for electromagnetic compatibility testing of aviation power supplies. It comprises a metal housing, a circuit module, connector interfaces, and a grounding assembly. The metal housing is formed by a base plate, a top panel, side panels, a front panel, and a rear panel. The top panel integrates multiple connector interfaces, while the front and rear panels are fitted with terminals. The circuit module is installed inside the metal housing and contains a built-in series resistor network. This series resistor network converts the input voltage signal into an acquireable test signal according to voltage distribution rules. The grounding assembly includes two L-shaped copper brackets, fastened to the metal housing with screws via a riveting structure. The bottoms of the two L-shaped copper brackets are welded to the grounding copper plate of the anechoic chamber test table, ensuring a low-impedance connection between the metal housing and the grounding system. This application allows for real-time monitoring of relevant voltage signals of the system, facilitating timely acquisition of fault signals and providing a direct view of the test conditions. The metal housing can be conveniently connected and welded to the anechoic chamber grounding copper plate, preventing interference signals from affecting the EMC test of the power supply system under test through poor grounding. Attached Figure Description

[0016] Figure 1 The structure and outline of a voltage distribution box provided in an embodiment of the voltage distribution box for electromagnetic compatibility testing of aviation power supplies in this application; Figure 2 The installation grounding of the voltage distribution box provided in one embodiment of the voltage distribution box for electromagnetic compatibility testing of aviation power supply in this application; Figure 3A connection diagram of a voltage distribution box provided in an embodiment of the voltage distribution box used for electromagnetic compatibility testing of aviation power supplies in this application, showing the connection relationship of the voltage distribution box in EMC testing; Figure 4 This application provides a test circuit diagram for a voltage distribution box used in electromagnetic compatibility testing of aviation power supplies, based on one embodiment. Figure 5 A series circuit of resistors provided in an embodiment of the prior art.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0019] The prior art upon which this invention is based is the voltage distribution rule, and the series relationship of resistors in the circuit is as follows: Figure 5 As shown.

[0020] Figure 5 The circuit shown in (a) is a series combination of n resistors R1, R2, ..., Rk, ..., Rn. When the resistors are connected in series, the current in each resistor is the same.

[0021] The voltage divider rule states that in a series circuit, the voltage supplied to each load is proportional to its impedance. Circuits built based on this principle are called voltage dividers. According to Kirchhoff's voltage law, in any closed loop, the algebraic sum of the electromotive forces in the loop is equal to the algebraic sum of the voltage drops across the resistors.

[0022]

[0023] Since the current in each resistor is I, we have U1 = R1I, U2 = R2I, ..., Uk = RkI, ..., Un = RnI. Substituting these into equation (1), we get:

[0024] The resistor Req is the equivalent resistance of these series resistors, see [reference needed]. Figure 5 (b) The equivalent resistance must be greater than any of the series resistors. When series resistors are connected, the voltage across each resistor should be:

[0025] The voltage across each resistor in series is proportional to its resistance. In other words, the total voltage is distributed according to the values ​​of the individual series resistors. Formula (3) is called the voltage distribution formula or the voltage divider formula.

[0026] In a series circuit with only two resistors (R1 and R2), the relevant calculation formula can be simplified to:

[0027] The purpose of this application is to address the problem of EMC impact on the AC power system during EMC testing of a certain type of aircraft, specifically in the process of acquiring and monitoring voltages at sensitive points to determine the actual operating state of the system during EMC testing. This application can be used for transmitting and converting voltage signals, as well as for monitoring POR voltage and related communication signals.

[0028] This application describes a voltage distribution box developed based on the actual needs of electromagnetic compatibility (EMC) testing of the main AC power supply system for a certain type of project. This application aims to minimize the impact of the voltage distribution box on the system's EMC testing, featuring a compact structure and small size for easy on-site installation and interface connection.

[0029] This application proposes a small, well-structured, and easy-to-install experimental auxiliary facility that can accurately verify relevant parameters in the testing of the data acquisition system, thus meeting the special requirements of the system's EMC testing.

[0030] Reference Figure 1 , Figure 1 This is a schematic diagram of a voltage distribution box structure for electromagnetic compatibility testing of aviation power supplies provided in the first embodiment of this application. The voltage distribution box may include: a metal housing 40, a circuit module 10, a connector interface 30, and a grounding component 20. The metal housing 40 is formed by a bottom plate, a top panel 401, a side panel 402, a front panel 403, and a rear panel. The top panel 401 integrates multiple sets of connector interfaces 30, and the front panel 403 and the rear panel are equipped with terminals. The circuit module 10 is installed inside the metal housing 40 and has a built-in series resistor network. The series resistor network converts the input voltage signal into an acquireable test signal according to the voltage distribution rule. The grounding component 20 includes two L-shaped copper brackets 201, which are fastened to the metal housing 40 by screws 202 through a riveting structure. The bottoms of the two L-shaped copper brackets 201 are respectively welded to the grounding copper plate of the anechoic chamber test table to make the metal housing 40 connected to the grounding system with low impedance.

[0031] In one embodiment of this application, the overlapping surfaces of the two L-shaped copper brackets 201 are gold-plated, and the surface roughness of the part in contact with the housing is no greater than Ra1.6μm. After assembly, the overlapping resistance between the two L-shaped copper brackets 201 and the housing is less than 2.5mΩ.

[0032] Specifically, refer to Figure 1The voltage distribution box mainly consists of: a base plate, a top panel 401, two side panels 402, a front panel 403, a rear panel, and two L-shaped copper brackets 201. Connector interfaces 30 are mounted on the top panel 401, and terminal blocks are mounted on the front and rear panels 403 and 402. The structural and external diagrams of the components of the voltage distribution box are shown below. Figure 2 As shown, this test auxiliary facility has many components. Once installed and assembled, these components do not need to be disassembled, forming a complete test fixture. When conducting EMC testing of the main AC power system of a certain type of aircraft in an anechoic chamber, it is only necessary to place the voltage distribution box in a fixed position within the system test area, and then weld its copper L-shaped bracket 201 to the grounding copper plate of the anechoic chamber test table for installation and fixation. (See...) Figure 3 After installation, it can be connected to the monitoring and display system via the corresponding coaxial cable through the communication interface board of the darkroom wall, so that the voltage signal or communication signal of the sensitive point of the tested system can be monitored. It is easy to use.

[0033] In one embodiment of this application, the circuit module 10 includes an AC signal processing unit and a DC signal processing unit; wherein, the AC unit includes a 115V / 400Hz voltage divider circuit, and the DC unit includes a 28V voltage filter circuit; the AC unit and the DC unit are connected to the test system through independent terminals.

[0034] In one embodiment of this application, the connector interface 30 includes nine sets of coaxial connectors, J1-J9. Among them, J1-J6 of the nine sets of coaxial connectors are used to output AC test signals of 10.45V±0.5V, and J7-J9 are used to output DC test signals of 2.55V±0.1V. The shielding layer of each of the nine sets of coaxial connectors is directly connected to the metal housing 40, and all nine sets of coaxial connectors are connected to the EMC testing laboratory through coaxial signal transmission lines and connected to communication monitoring equipment to monitor the voltage signals in real time.

[0035] Understandably, the voltage distribution box is connected to the product under test in the AC power system of a certain type of civil aircraft. It consists of both AC and DC components and is primarily used in system testing to collect and monitor voltages at sensitive points, determine the actual operating status of the system, and transmit and convert voltage signals. The voltage distribution box is also connected to the image recording device in the EMC control room for monitoring the POR voltage and related communication signals. The circuit diagram of this voltage distribution box is shown below. Figure 4 As shown.

[0036] In one embodiment of this application, the AC unit includes at least one set of three-phase AC input circuits, each set of three-phase AC input circuits including three-phase lines and a neutral line; wherein, one end of each of the three-phase lines is connected in series with a first LC filter circuit and an overcurrent protection element, and the other end of each is connected through a first resistor and a coaxial connector, the output end of the coaxial connector is also connected to the neutral line and a ground line, and the input end of each coaxial connector is connected to the neutral line through a second resistor; the input end of the neutral line is connected in series with a second LC filter circuit and a ground line. The first resistor has a resistance of 1MΩ, and the second resistor has a resistance of 100KΩ.

[0037] The three-phase AC input circuit consists of two sets. The coaxial connectors for both the first and second sets of three-phase AC input circuits include coaxial connectors J1 through J6. All coaxial connectors (J1 through J6) are BNC adapters. The AC input voltage for each three-phase line is 115V.

[0038] In one embodiment of this application, the DC unit includes a set of three-phase DC input circuits, each set of three-phase DC input circuits including three-phase lines and a neutral line; wherein, one end of each of the three-phase lines is connected in series with a third LC filter circuit and an overcurrent protection element, and the other end of each is connected through a third resistor and a coaxial connector, the output end of the coaxial connector is also connected to the neutral line and a ground line, and the input end of each coaxial connector is connected to the neutral line through a fourth resistor; the input end of the neutral line is connected in series with a fourth LC filter circuit and a ground line. The DC input voltage of the three-phase lines is 28V.

[0039] The key technical issues addressed in the design of this voltage distribution box are as follows: The voltage distribution box uses easily replaceable components, and replacement spare parts (resistors of corresponding resistance values ​​in the circuit, power input filters, NBC adapters, etc.) are also provided with the equipment, so that faults can be replaced in a timely manner during the test.

[0040] The designed and manufactured voltage distribution box is small in size and compact in structure, occupying little effective space in practical engineering applications. Its impact on test results is within a controllable range and has no impact on related tests carried out by the system.

[0041] The L-shaped copper connecting bracket of the voltage distribution box is easy to solder to the grounding copper plate of a field test table in an EMC laboratory, making installation and disassembly relatively convenient.

[0042] The L-shaped copper connecting bracket, designed with a special riveting structure, is fastened to the voltage distribution box with screws 202. The two metal surfaces are in close contact, and the lap resistance is less than 2.5mΩ.

[0043] The J-terminal of the voltage distribution box is connected to an EMC testing laboratory via a coaxial signal transmission line, and is connected to the communication monitoring equipment outside the dark room. It is controlled by a dedicated software system, which sends and receives communication signals according to the system test requirements, monitors the relevant voltage signals of the system in real time, and can conveniently and timely obtain fault signals, and can intuitively observe the test situation.

[0044] The voltage distribution box has a specially designed grounding point inside, which is connected to the metal casing 40 of the equipment and welded to the grounding copper plate of the anechoic chamber to prevent interference signals from affecting the power supply system under test through poor grounding.

[0045] In addition to the design and manufacturing technical requirements and test outline, this application also conducted performance checks and tests on the voltage distribution box after its manufacture. The verification data is shown in Table 1. As can be seen from the data in Table 1, all parameters meet the requirements, the overall conclusion is qualified, and it meets the requirements for participating in system testing.

[0046] This application describes the design and manufacture of a voltage distribution box based on the specific requirements of the maiden flight and qualification electromagnetic compatibility test of the AC power system of a certain type of aircraft. It has been applied in engineering practice, ensuring the smooth progress of the maiden flight and qualification electromagnetic compatibility test of the power system of a certain type of aircraft, and providing a guarantee for the delivery and development of related products.

[0047] Based on the system test procedures and relevant clauses of the RTCA / DO-160F standard, this voltage distribution box has participated in EMC first flight tests and qualification tests related to the AC power system of a certain type of civil aircraft. The voltage distribution box is connected to the monitoring and display system of an EMC testing laboratory, enabling real-time monitoring of system test data. It primarily collects data on whether the POR voltage analog signal output during system operation is within the required range and whether there are any abnormalities in the system communication digital signal. If, during the test, the POR voltage analog signal experiences large fluctuations exceeding the tolerance requirements of the test outline, or if the system experiences power outages, protection failures, or other issues; or if the system communication digital signal exhibits fault codes, communication interruptions, or crashes that cannot be restarted, these phenomena must be recorded, and the test failures must be described and evaluated. According to the report provided by the EMC testing laboratory, the voltage distribution box involved in the test can transmit the POR voltage analog signal and system communication digital signal to the monitoring and display system in the EMC shielded control room in real time.

[0048] Meanwhile, the voltage distribution box withstood the harsh electromagnetic environment conditions, and its functions were normal, its performance was good, its reliability was high, and its signal transmission was stable. During the overall test, no failure of the voltage distribution box affected the test process, effectively ensuring the smooth completion of the relevant EMC tests of the AC power system of a certain type of aircraft.

[0049] Table 1. Voltage Distribution Box Verification Data

[0050] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A voltage distribution box for electromagnetic compatibility testing of aviation power supplies, characterized in that, include: Metal housing, circuit modules, connector interfaces, and grounding components; The metal housing is formed by a bottom plate, a top plate, side plates, a front plate, and a rear plate. The top plate integrates multiple connector interfaces, and the front and rear plates are equipped with terminal blocks. The circuit module is installed inside a metal casing. The circuit module has a built-in series resistor network, which converts the input voltage signal into an acquireable test signal according to the voltage distribution rule. The grounding assembly includes two L-shaped copper brackets, which are fastened to the metal housing with screws by a riveting structure. The bottom of the two L-shaped copper brackets are respectively welded to the grounding copper plate of the anechoic chamber test table so that the metal housing is connected to the grounding system with low impedance.

2. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 1, characterized in that, The circuit module includes an AC signal processing unit and a DC signal processing unit; The AC unit includes a 115V / 400Hz voltage divider circuit, and the DC unit includes a 28V voltage filter circuit. The AC and DC units are connected to the system under test via independent terminals.

3. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 1, characterized in that, The connector interface includes 9 sets of coaxial connectors, J1-J9; Among them, J1-J6 of the 9 coaxial connectors are used to output AC test signals of 10.45V±0.5V, and J7-J9 are used to output DC test signals of 2.55V±0.1V. The shielding layer of each of the 9 coaxial connectors is directly connected to the metal shell. All 9 coaxial connectors are connected to the EMC testing laboratory through coaxial signal transmission lines and are connected to communication monitoring equipment to monitor the voltage signals in real time.

4. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 1, characterized in that, The overlapping surfaces of the two L-shaped copper brackets are gold-plated, and the surface roughness of the part in contact with the shell is no greater than Ra1.6μm. After assembly, the overlapping resistance between the two L-shaped copper brackets and the shell is less than 2.5mΩ.

5. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 1, characterized in that, The AC unit includes at least one set of three-phase AC input circuits, and each set of three-phase AC input circuits includes three-phase lines and a neutral line; In this configuration, one end of each of the three phase lines is connected in series with a first LC filter circuit and an overcurrent protection element, and the other end of each phase line is connected through a first resistor and a coaxial connector. The output end of the coaxial connector is also connected to the neutral line and the ground line, and the input end of each coaxial connector is connected to the neutral line through a second resistor. The input end of the neutral line is connected in series with a second LC filter circuit and a ground line. The first resistor has a resistance of 1 MΩ and the second resistor has a resistance of 100 kΩ.

6. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 5, characterized in that, The number of three-phase AC input circuits is two sets. The coaxial connectors of the first set of three-phase AC input circuits and the second set of three-phase AC input circuits include coaxial connectors J1-J6.

7. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 1, characterized in that, All J1-J6 coaxial connectors are BNC adapters.

8. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 5, characterized in that, The AC input voltage of each of the three phase lines is 115V.

9. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 1, characterized in that, The DC unit includes a set of three-phase DC input circuits, and each set of three-phase DC input circuits includes three-phase lines and a neutral line; In this configuration, one end of each of the three phase lines is connected in series with a third LC filter circuit and an overcurrent protection element, and the other end of each phase line is connected to a third resistor and a coaxial connector. The output end of the coaxial connector is also connected to the neutral line and the ground line, and the input end of each coaxial connector is connected to the neutral line through a fourth resistor. The input end of the neutral line is connected in series with the fourth LC filter circuit and the ground line.

10. The voltage distribution box for electromagnetic compatibility testing of aviation power supplies as described in claim 9, characterized in that, The DC input voltage of the three-phase line is 28V.

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