EMC large rotary table electric control cabinet shielding structure and shielding method thereof

Abstract

The application discloses an EMC large rotary table electric control machine box shielding structure and a shielding method thereof, which comprises: machine box components arranged in the inside of a machine box shell, and motor components connected with the machine box shell; the machine box components comprise: a first wiring unit, a first filter unit, a second filter unit, a frequency conversion unit, a frequency conversion filter unit, a motor power supply unit, a coding unit and a second wiring unit; a partition plate is arranged between each unit; the motor power supply unit, the second wiring unit and the coding unit are connected with the motor components through corrugated pipes; electromagnetic field intensity sensors are arranged at the two ends of the corrugated pipes; a connecting cable is arranged in the corrugated pipe; the cross section of the corrugated pipe is an ellipse; the length of the short axis of the ellipse is equal to the outer diameter of the cable; a plurality of corrugated grooves are arranged on the surface of the corrugated pipe, and the corrugated grooves are spherical biaugmented triangular structures. The shielding structure can effectively reduce the generation and propagation of electromagnetic interference, and improve the stability and reliability of the equipment.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology, and in particular to a shielding structure and shielding method for an EMC large turntable electrical control chassis. Background Technology

[0002] Electromagnetic compatibility (EMC) refers to the ability of a device or system to operate within its electromagnetic environment without causing unacceptable electromagnetic interference to any other equipment in that environment. The main factors that cause EMC to degrade the performance of equipment, transmission channels, or systems include natural and man-made sources of interference, coupling through common ground impedance / internal resistance, conducted electromagnetic interference along power lines, and radiated interference.

[0003] In existing technologies, professional filters are generally used to eliminate interference noise in order to meet electromagnetic compatibility requirements. However, these filters only filter the power input and output and do not adequately address the interference sources on the power lines, leading to the potential for excessive noise floor. Furthermore, while overall shielding of the chassis is used to meet electromagnetic compatibility requirements, the inverter can interfere with the power supply and low-voltage compartment, causing interference sources to spill over and resulting in excessive noise floor. Additionally, the lack of any treatment for the motor brakes, encoders, and power line connections leads to insufficient grounding of the shielding box, resulting in unstable noise floor.

[0004] Meanwhile, in high-intensity electromagnetic field environments such as high-voltage power transmission, large electric motors, and high-frequency welding machines, as well as in environments with dense electromagnetic radiation such as radar, satellite communication, and radio and television transmission stations, cables are susceptible to strong electromagnetic interference. This interference may be transmitted through the conductors of the cable, affecting the integrity of the signal or damaging the cable. Furthermore, during use, cables may expand due to temperature changes, resulting in uneven distribution of electromagnetic fields inside the cable, causing voltage and current fluctuations, thereby enhancing the impact of electromagnetic interference.

[0005] Therefore, there is a need to provide a shielding structure and shielding method for the EMC large turntable electrical control chassis to solve the above problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a shielding structure and shielding method for the electrical control chassis of an EMC large turntable.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a shielding structure for an EMC large turntable electrical control chassis, comprising: a chassis shell, chassis components disposed inside the chassis shell, and motor components connected to the chassis shell, characterized in that... The chassis components include: a first wiring unit, a first filtering unit, a second filtering unit, a frequency conversion unit, a frequency conversion filtering unit, a motor power supply unit, an encoding unit, and a second wiring unit; each unit is provided with a partition plate to divide the chassis shell into several compartments; The motor component includes: a geared motor, a first junction box disposed outside the geared motor, an output shaft end disposed at one end of the geared motor, and a second junction box disposed at the other end of the geared motor. The motor power supply unit, the second wiring unit, and the encoding unit are all connected to the motor component through bellows; each end of the bellows is equipped with an electromagnetic field strength sensor to measure the electromagnetic field strength value at different positions of the bellows in real time. The corrugated pipe has a connecting cable inside. The cross-section of the corrugated pipe is elliptical. The minor axis of the cross-section of the corrugated pipe is equal to the outer diameter of the cable. The surface of the corrugated pipe is provided with a plurality of corrugated grooves, which are spherical diagonal structures.

[0008] In a preferred embodiment of the present invention, a gear is provided inside the output shaft end, and a shielding pressure plate and a shielding pad are provided on one side of the gear.

[0009] In a preferred embodiment of the present invention, the encoding unit is connected to the output shaft end through the bellows, and both the encoding unit and the connection point between the output shaft end and the bellows are provided with shielding covers.

[0010] In a preferred embodiment of the present invention, the first filtering unit is provided with a first military three-phase AC filter, which performs two-stage filtering through three-phase power input; the second filtering unit is provided with a second military three-phase AC filter, which performs one-stage filtering through three-phase power input.

[0011] In a preferred embodiment of the present invention, the second wiring unit is further provided with a brake end and a fan end; the first junction box is connected to the motor terminal block and the fan end through the corrugated pipe; the second junction box is connected to the brake end through the corrugated pipe.

[0012] In a preferred embodiment of the present invention, the first military three-phase AC filter is installed inside the compartment, and the second military three-phase AC filter is installed outside the compartment and connected by a metal pipe passing through the compartment plate.

[0013] In a preferred embodiment of the present invention, the encoding unit is provided with a power board and a PCB control board, and a single-correlation military standard plug is provided on one side of the encoding unit; the encoding unit is communicatively connected to the central control terminal.

[0014] In a preferred embodiment of the present invention, a chassis cover is provided on the outside of the chassis housing.

[0015] This invention also provides a shielding method for the shielding structure of an EMC large turntable electrical control chassis, characterized by comprising the following steps: S1. Full welding is performed at all joints of the chassis to fix the chassis components and motor components inside the chassis and connect the wires. Install the shielding cover and power on for testing. S2. After installing the chassis cover, thread the cable through the corrugated pipe, shield the motor output shaft end, and connect the motor UVW line to the fan end and brake end, and connect it to the encoder unit at the same time. S3. Test the bellows and obtain the optimal bellows. Use the optimal bellows to conduct a noise floor test and obtain the test results.

[0016] In a preferred embodiment of the present invention, the specific steps in S3 for testing the bellows and obtaining the optimal bellows include: S31. Electromagnetic field strength sensors are installed at both ends of several bellows, and target field strength data is set. Electromagnetic field strength data is collected in real time during the background noise test. S32. Send the electromagnetic field strength data to the central control terminal, compare the measured field strength data with the target field strength data, and determine whether the current corrugated pipe can meet the requirements. S33. Adjust the major axis length, corrugation length, corrugation distance and corrugation thickness of the corrugated pipe cross section, and record the field strength change curves under different parameters, and select the corrugated pipe with the optimal parameters.

[0017] This invention addresses the shortcomings of the prior art and has the following beneficial effects: This invention provides a shielding structure and method for an EMC large turntable electrical control chassis. The shielding structure uses partition plates to divide the chassis shell into several compartments, which can avoid the problem of easy interference in high-intensity electromagnetic field environments in the prior art, and effectively reduce the generation and propagation of electromagnetic interference. At the same time, the design of corrugated pipes, shielding pressure plates and shielding gaskets further enhances the electromagnetic shielding effect and improves the stability and reliability of the equipment.

[0018] This invention reduces the frequency of electromagnetic interference transmitted between components by dividing each unit of the chassis into high and low pressure compartments. The compartments are made of iron plates with good electromagnetic shielding properties and are galvanized to ensure good electromagnetic shielding properties and prevent corrosion of the compartments.

[0019] In this invention, the power control box output uses high-pressure oil pipes for shielding, reducing external radiated interference. Furthermore, the threaded connectors at both ends of the high-pressure oil pipe and the outer wall of the pipe are made of metal, providing excellent conductivity and enhancing the electromagnetic shielding effect of the signal lines. Simultaneously, the paint layer of the first junction box is milled off for shielding, and the paint layer is also milled off at the contact point between the first junction box and the cover plate. A shielding strip is then pasted at the contact point, ensuring good electrical continuity between the motor junction box and the cover plate, further strengthening the electromagnetic shielding effect.

[0020] The present invention uses a shielding gasket and a pressure plate for shielding the output shaft of the geared motor. The shielding gasket is a beryllium copper braided pad, which has good conductivity, wear resistance and good resistance to metal fatigue. The inner diameter of the beryllium copper braided pad is slightly smaller than that of the motor output shaft, which ensures good contact between the pad and the motor output shaft. The pressure plate firmly presses the beryllium copper braided pad onto the output shaft of the geared motor, further ensuring good electrical continuity between the motor output shaft, the beryllium copper braided pad and the geared motor housing.

[0021] This invention involves uniformly arranging several electromagnetic field strength sensors around the interface between the corrugated pipe and the shielding layer. This enables comprehensive monitoring of these areas, allowing for timely capture and analysis of electromagnetic interference from all directions, ensuring effective protection of the equipment under various working environments. Simultaneously, it can collect a large amount of data from real-world working scenarios, which can not only be used to evaluate the performance of the current shielding structure but also provide a basis for further optimizing the design of the shielding layer, thereby continuously improving the electromagnetic shielding performance of the equipment.

[0022] This invention uses an elliptical corrugated tube, with the short side of the ellipse tightly attached to the cable for fixation, and the long side for buffering, accommodating the deformation of the cable due to expansion. This achieves better shielding effect, increases the possibility of external electromagnetic waves entering and reduces electromagnetic leakage. At the same time, the electric field distribution inside the ellipse is more uniform, and the number of reflections of electromagnetic waves between the inner walls is significantly increased compared to a circular corrugated tube, causing energy to attenuate rapidly, thereby increasing the shielding depth. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is an overall three-dimensional structural diagram of a preferred embodiment of the present invention; Figure 2 This is a three-dimensional structural diagram of the chassis component according to a preferred embodiment of the present invention; Figure 3This is a schematic diagram of the chassis components according to a preferred embodiment of the present invention; Figure 4 This is a three-dimensional structural view of the motor component according to a preferred embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a motor component according to a preferred embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a bellows according to a preferred embodiment of the present invention; Figure 7 This is a flowchart of a preferred embodiment of the present invention; Figure 8 This is a graph showing the noise floor test results of Comparative Example 1 of the present invention; Figure 9 This is a graph showing the noise floor test results of Comparative Example 2 of the present invention; Figure 10 This is a graph showing the noise floor test results of Comparative Example 3 of the present invention; Figure 11 This is a graph showing the noise floor test results of Comparative Example 4 of the present invention; Figure 12 This is a graph showing the noise floor test results of Embodiment 1 of the present invention; In the diagram: 1. Chassis housing; 2. Chassis components; 21. First wiring unit; 211. First terminal block; 22. First filter unit; 221. First military-grade three-phase AC filter; 23. Second filter unit; 231. Second military-grade three-phase AC filter; 24. Frequency converter unit; 241. Frequency converter; 242. Braking resistor; 25. Frequency converter filter unit; 251. Frequency converter output filter; 26. Motor power supply unit; 261. Motor terminal block; 27. Encoding unit; 271, Power board; 272, PCB control board; 273, Single-correlation military standard plug; 28, Second wiring unit; 281, Brake end; 282, Fan end; 283, Second terminal block; 29, Partition plate; 3, Motor components; 31, Gear motor; 32, First junction box; 33, Output shaft end; 331, Gear; 332, Shielding pressure plate; 333, Shielding gasket; 34, Second junction box; 4, Corrugated pipe; 5, Shielding cover; 6, Chassis cover. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1As shown, an EMC large turntable electrical control chassis shielding structure includes: a chassis shell 1, a chassis component 2 disposed inside the chassis shell 1, and a motor component 3 connected to the chassis body; a chassis cover 6 is disposed outside the chassis shell 1.

[0026] The shielding structure uses partition plates 29 to divide the chassis shell 1 into several compartments, which can avoid the problem of easy interference in the high-intensity electromagnetic field environment in the prior art, and effectively reduce the generation and propagation of electromagnetic interference. At the same time, the design of corrugated pipe 4, shielding pressure plate 332 and shielding gasket 333 further enhances the electromagnetic shielding effect and improves the stability and reliability of the equipment.

[0027] like Figure 2 As shown, the chassis component 2 includes: a first wiring unit 21, a first filtering unit 22 and a second filtering unit 23, a frequency conversion unit 24, a frequency conversion filtering unit 25, a motor power supply unit 26, an encoding unit 27, a second wiring unit 28, and a partition plate 29 disposed between each unit.

[0028] Several partition plates 29 separate each unit into high-pressure and low-pressure compartments, reducing the frequency of electromagnetic interference transmitted by each component. The partition plates 29 are made of iron plates with good electromagnetic shielding properties and are treated with galvanizing process to ensure good electromagnetic shielding properties and prevent the partition plates 29 from rusting.

[0029] like Figure 3 As shown, a first terminal block 211 is provided between the first wiring unit 21 and the frequency converter unit 24.

[0030] The first filtering unit 22 is equipped with a first military three-phase AC filter 221, which performs two-stage filtering through three-phase power input; the second filtering unit 23 is equipped with a second military three-phase AC filter 231, which performs one-stage filtering through three-phase power input.

[0031] It should be noted that both the first military three-phase AC filter 221 and the second military three-phase AC filter 231 are EMF-15SDB high-current AC filters used to prevent interference noise inside the chassis from leaking to the outside of the chassis through the AC power line. The first military three-phase AC filter 221 is installed inside the compartment, and the second military three-phase AC filter 231 is installed outside the compartment, connected by a metal tube passing through the compartment plate 29. This filter can filter out interference noise of a specific frequency while ensuring that the system leakage current is minimized.

[0032] The frequency converter 24 is equipped with a frequency converter 241 and a braking resistor 242.

[0033] The inverter filter unit 25 contains an output filter for the inverter 241. The inverter 241 output filter, model DTD-10 / 15-J, is used to prevent interference noise generated by the inverter 241 inside the chassis from leaking to the outside of the shielded enclosure through the motor power lines. The inverter 241 output filter is installed inside the compartment and passes through the compartment plate 29 via a metal pipe. This filter can filter out interference noise of specific frequencies while still meeting the normal control requirements of the servo drive for the servo motor.

[0034] The motor power supply unit 26 is equipped with a motor terminal block 261, which is preferably a TB1503 type terminal block.

[0035] The encoding unit 27 contains a power board 271 and a PCB control board 272. A single-related military standard plug 273 is provided on one side of the encoding unit 27. The encoding unit 27 is connected to the central control terminal for communication.

[0036] The second wiring unit 28 is provided with a second terminal block 283; the second terminal block 283 is preferably a TB-1506 type terminal block; the second wiring unit 28 is also provided with a brake end 281 and a fan end 282.

[0037] The encoding unit 27 is connected to the output shaft end 33 through the bellows 4, and both the encoding unit 27 and the output shaft end 33 are provided with shields 5 at the connection points with the bellows 4.

[0038] The outgoing cables of the chassis shielding structure are shielded using high-pressure oil pipes to reduce external radiation interference; the threaded connectors at both ends of the high-pressure oil pipe and the outer wall of the oil pipe are made of metal, and the whole has good conductivity.

[0039] The motor power supply unit 26, the second wiring unit 28, and the encoding unit 27 are all connected to the motor component 3 via the bellows 4. The bellows 4 is preferably made of stainless steel.

[0040] like Figure 4 As shown, the motor component 3 includes: a geared motor 31, a first junction box 32 disposed outside the geared motor 31, an output shaft end 33 disposed at one end of the geared motor 31, and a second junction box 34 disposed at the other end of the geared motor 31.

[0041] like Figure 5 As shown, the first junction box 32 is connected to the motor terminal block 261 and the fan end 282 through the bellows 4; the second junction box 34 is connected to the brake end 281 through the bellows 4; a gear 331 is provided inside the output shaft end 33, and a shielding pressure plate 332 and a shielding pad 333 are provided on one side of the gear 331.

[0042] The paint layer of the first junction box 32 is milled off and shielded. The paint layer at the contact point between the first junction box 32 and the cover plate is milled off, and then a shielding strip is pasted at the contact point to ensure good electrical continuity at the contact point between the motor junction box and the cover plate.

[0043] The shielding gasket 333 is made of beryllium copper braided steel. This shielding gasket 333 has good conductivity, wear resistance, and good resistance to metal fatigue. The inner diameter of the beryllium copper braided steel gasket is smaller than that of the motor output shaft to ensure good contact between the steel gasket and the motor output shaft. The shielding pressure plate 332 presses the shielding gasket 333 onto the output shaft of the geared motor 31, so that there is good electrical continuity between the motor output shaft, the beryllium copper braided steel gasket, and the housing of the geared motor 31.

[0044] like Figure 6 As shown, a connecting cable is installed inside the corrugated pipe 4. The cross-section of the corrugated pipe 4 is elliptical, and several corrugated grooves are provided on the surface of the corrugated pipe 4. The corrugated grooves and the corrugated pipe 4 form an elliptical structure, and the minor axis of the cross-section is equal to the outer diameter of the cable.

[0045] The two spherical angles of the corrugated groove are both α, and the area S of the spherical diagonal is... 槽 =2R 2 Let L be the radius of the sphere, R be the radius of the sphere, and L be the spherical angle in radians. L = α * π / 180°, and the spherical angle α is in the range of 0° < α < 90°. Then the cross-sectional area of ​​the elliptical structure is S. 管 =2*S 球 +πr 2 =4R 2 α+πr 2 , where r represents the radius of the cross-section of the bellows 4.

[0046] Therefore, it can be seen that the cross-sectional area utilization rate of the elliptical structure is higher than that of the circular structure, and a larger shielding area can be achieved with the same cross-sectional area; at the same time, the elliptical structure can form a more uniform electric field distribution, and it is easier to achieve a three-dimensional shielding effect compared with the circular structure.

[0047] The cable is fixed by the short side of the elliptical corrugated tube 4, while the long side is used for buffering to accommodate the deformation of the cable due to expansion. This achieves a better wrapping effect, increases the possibility of external electromagnetic waves entering and reduces electromagnetic leakage. At the same time, the electric field distribution inside the elliptical tube is more uniform, and the number of reflections of electromagnetic waves between the inner walls is significantly increased compared to the circular corrugated tube 4, causing the energy to decay rapidly and thus increasing the shielding depth.

[0048] Electromagnetic field strength sensors are installed at both ends of several bellows 4 to measure the electromagnetic field strength at different locations on the bellows 4 in real time. The electromagnetic field strength sensors are preferably Hall effect sensors.

[0049] Electromagnetic field strength sensors can achieve all-round monitoring of these areas. No matter which direction the electromagnetic interference originates from, it can be captured and analyzed in a timely manner, ensuring that the equipment is effectively protected in various working environments. At the same time, it can collect a large amount of data in real working scenarios, which can not only be used to evaluate the performance of the current shielding structure, but also provide a basis for further optimization of the shielding layer design, thereby continuously improving the electromagnetic shielding performance of the equipment.

[0050] like Figure 7 As shown, a shielding method for an EMC large turntable electrical control chassis shielding structure includes the following steps: S1. Full welding is performed at all joints of the chassis. The chassis component 2 and motor component 3 are fixed inside the chassis and wired. The shielding cover 5 is installed and the power is turned on for testing. S2. After installing the chassis cover plate 6, thread the cable through the corrugated pipe 4, shield the motor output shaft end 33, and connect the motor UVW line to the fan end 282 and the brake end 281, and connect it to the encoder unit 27 at the same time. S3. Electromagnetic field strength sensors are installed at both ends of several bellows 4. The target field strength data is set, and electromagnetic field strength data is collected in real time during the background noise test. The electromagnetic field strength data is sent to the central control terminal, and the measured field strength data is compared with the target field strength data to determine whether the current corrugated pipe 4 can meet the requirements. The major axis length, corrugation length, corrugation distance, and thickness of the corrugated pipe 4 were adjusted, and the field strength variation curves under different parameters were recorded. The corrugated pipe 4 with the optimal parameters was selected. The noise floor test was conducted using the optimal corrugated pipe 4, and the test results were obtained. Example

[0051] This embodiment provides a shielding method for the shielding structure of an EMC large turntable electrical control chassis, including the following steps: S1. Full welding is performed at all joints of the chassis. The chassis component 2 and motor component 3 are fixed inside the chassis and wired. The shielding cover 5 is installed and the power is turned on for testing. S2. After installing the chassis cover plate 6, thread the cable through the elliptical corrugated pipe 4, where the spherical angle of the corrugated groove is 1°, the spherical radius is 0.5cm, the diameter of the corrugated pipe 4 is 1cm, shield the motor output shaft end 33, and connect the motor UVW line to the fan end 282 and the brake end 281, and connect it to the encoding unit 27 at the same time. S3. Electromagnetic field strength sensors are installed at both ends of several bellows 4. The target field strength data is set, and electromagnetic field strength data is collected in real time during the background noise test. The electromagnetic field strength data is sent to the central control terminal, and the measured field strength data is compared with the target field strength data to determine whether the current corrugated pipe 4 can meet the requirements. The major axis length, corrugation length, corrugation distance, and thickness of the corrugated pipe 4 were adjusted, and the field strength variation curves under different parameters were recorded. The corrugated pipe 4 with the optimal parameters was selected. The noise floor test was conducted using the optimal corrugated pipe 4, and the test results were obtained.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that no treatment was performed on the chassis in this comparative example.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, in S2, no chassis cover is provided on the outside of the chassis housing.

[0054] Comparative Example 3 The difference between this comparative example and Example 1 is that, in this comparative example, stainless steel corrugated pipes were not used for connection in S2.

[0055] Comparative Example 4 The difference between this comparative example and Example 1 is that in this comparative example, the output shaft end of the motor is not shielded in S2.

[0056] Comparative Example 5 The difference between this comparative example and Example 1 is that in this comparative example, the spherical angle of the corrugated groove is 89° in S2.

[0057] Comparative Example 6 The difference between this comparative example and Example 1 is that in this comparative example, the bellows has a circular structure in S2.

[0058] Experimental Example 1 The shielding area and shielding effect of Example 1, Comparative Examples 5 and 6 were compared using an electromagnetic shielding tester. The test site was a quiet indoor environment with no significant environmental noise interference. The shielding effectiveness in the 1GHz frequency band was tested using a frequency sweep meter. The data obtained are shown in the table below.

[0059] Table 1 Summary of shielding effect data As shown in the table above, compared with Comparative Example 6 (without a spherical angle), the shielding performance of Examples 1 and 5 (with a spherical angle) is significantly improved, indicating that an elliptical structure can improve shielding performance. Specifically, the spherical radius and bellows radius are the same in Examples 1 and 5, but the spherical angle (89°) of Comparative Example 5 is greater than that of Example 1 (1°), and its shielding area (2.338 cm²) is also greater. 2 It is also larger than that of Example 1 (0.802cm). 2However, the shielding performance of Example 1 (>30dB) is lower than that of Comparative Example 5 (>40dB).

[0060] This indicates that, keeping other parameters constant, the size of the spherical angle setting affects the shielding area and shielding performance, and the shielding performance improves as the spherical angle increases.

[0061] Experimental Example 2 Noise floor tests were conducted on Comparative Examples 1-4 in a quiet indoor environment with no significant ambient noise interference. The input noise frequency band was 30Hz-1GHz, and the measurement frequency band was 30-1000MHz. The results are as follows. Figures 8-11 It can be seen that the background noise is excessive; Figure 8 This is a schematic diagram of the noise floor measured without any treatment of the chassis. Figure 9 The diagram shows the noise floor measured without a chassis cover on the outside of the chassis. It can be seen that the peak and trough distribution of Comparative Example 1 and Comparative Example 2 are uneven, and the noise floor fluctuates greatly. The noise floor in both cases exceeds the standard. Figure 10 This is a schematic diagram showing the noise floor measured without the use of stainless steel corrugated pipes for connection. Figure 11 The diagram shows the noise floor measured without shielding the output shaft of the motor. It can be seen that the peaks and valleys of Comparative Example 3 and Comparative Example 4 are relatively evenly distributed, but there are still a few bands with large noise floor fluctuations, and the noise floor is exceeded in all cases.

[0062] Next, a noise floor test was conducted on Example 1. The test site was a quiet indoor environment with no significant environmental noise interference. The input noise frequency band was 30Hz-1GHz, and the measurement frequency band was 30-1000MHz. The results are as follows: Figure 12 It can be seen that the background noise is qualified. The peaks and valleys of Example 1 are evenly distributed, and there are no bands with large background noise fluctuations. Therefore, the background noise is qualified.

[0063] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A shielding structure for the electrical control chassis of an EMC large turntable, comprising: A chassis housing, chassis components disposed inside the chassis housing, and a motor component connected to the chassis housing, characterized in that: The chassis components include: a first wiring unit, a first filtering unit, a second filtering unit, a frequency conversion unit, a frequency conversion filtering unit, a motor power supply unit, an encoding unit, and a second wiring unit; each unit is provided with a partition plate to divide the chassis shell into several compartments; The motor component includes: a geared motor, a first junction box disposed outside the geared motor, an output shaft end disposed at one end of the geared motor, and a second junction box disposed at the other end of the geared motor. The motor power supply unit, the second wiring unit, and the encoding unit are all connected to the motor component through bellows; each end of the bellows is equipped with an electromagnetic field strength sensor to measure the electromagnetic field strength value at different positions of the bellows in real time. The corrugated pipe has a connecting cable inside. The cross-section of the corrugated pipe is elliptical. The minor axis of the cross-section of the corrugated pipe is equal to the outer diameter of the cable. The surface of the corrugated pipe is provided with a plurality of corrugated grooves, which are spherical diagonal structures.

2. The shielding structure of the EMC large turntable electrical control chassis according to claim 1, characterized in that: A gear is provided inside the output shaft end, and a shielding pressure plate and a shielding gasket are provided on one side of the gear.

3. The shielding structure of the EMC large turntable electrical control chassis according to claim 1, characterized in that: The encoding unit is connected to the output shaft end through the bellows, and both the encoding unit and the connection point between the output shaft end and the bellows are provided with shielding covers.

4. The shielding structure of the EMC large turntable electrical control chassis according to claim 1, characterized in that: The first filtering unit is equipped with a first military-grade three-phase AC filter, which performs two-stage filtering through three-phase power input; the second filtering unit is equipped with a second military-grade three-phase AC filter, which performs one-stage filtering through three-phase power input.

5. The shielding structure of the EMC large turntable electrical control chassis according to claim 1, characterized in that: The second wiring unit is also provided with a brake end and a fan end; the first junction box is connected to the motor power unit and the fan end through the corrugated pipe; the second junction box is connected to the brake end through the corrugated pipe.

6. The shielding structure of the EMC large turntable electrical control chassis according to claim 4, characterized in that: The first military three-phase AC filter is installed inside the compartment, and the second military three-phase AC filter is installed outside the compartment, connected by a metal pipe passing through the compartment plate.

7. The shielding structure of the EMC large turntable electrical control chassis according to claim 1, characterized in that: The encoding unit contains a power board and a PCB control board, and a single-correlation military standard plug is provided on one side of the encoding unit; the encoding unit is communicatively connected to the central control terminal.

8. The shielding structure of the EMC large turntable electrical control chassis according to claim 1, characterized in that: The chassis shell is equipped with a chassis cover.

9. A shielding method based on any one of the shielding structures of the EMC large turntable electrical control chassis as described in claims 1-8, characterized in that, Includes the following steps: S1. Full welding is performed at all joints of the chassis to fix the chassis components and motor components inside the chassis and connect the wires. Install the shielding cover and power on for testing. S2. After installing the chassis cover, thread the cable through the corrugated pipe, shield the motor output shaft end, and connect the motor UVW line to the fan end and brake end, and connect it to the encoder unit at the same time. S3. Test the bellows and obtain the optimal bellows. Use the optimal bellows to conduct a noise floor test and obtain the test results.

10. The shielding method for the shielding structure of an EMC large turntable electrical control chassis according to claim 9, characterized in that: In step S3, the specific steps for testing the bellows and obtaining the optimal bellows include: S31. Electromagnetic field strength sensors are installed at both ends of several bellows, and target field strength data is set. Electromagnetic field strength data is collected in real time during the background noise test. S32. Send the electromagnetic field strength data to the central control terminal, compare the measured field strength data with the target field strength data, and determine whether the current corrugated pipe can meet the requirements. S33. Adjust the major axis length, corrugation length, corrugation distance and corrugation thickness of the corrugated pipe cross section, and record the field strength change curves under different parameters, and select the corrugated pipe with the optimal parameters.

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