The EMI filter circuit is used to enable the final product to meet applicable electromagnetic compatibility standards. Most electrical and electronic equipment generates electromagnetic interference and is affected by electromagnetic interference. It is ubiquitous, so it is necessary to discuss the comprehensive solution of conducted electromagnetic interference noise.
2 Theoretical analysis
In various noise networks, the structure of the MARDIGUIAN separation network is relatively simple, but due to the existence of parasitic capacitance and the output characteristics of the interference differential mode, the common model noise is affected, resulting in an increase in the common mode rejection ratio of the separation network. .
3 noise diagnosis
Based on current characteristics and interference voltage, using modern experimental equipment, using the principle of stable network, using noise diagnosis technology for analysis, in general, in actual work, because the mechanism of interference is different, then in actual suppression The method will be different. The following are mainly used. The first is the RF radio wave probe. According to the Faraday principle, the interference current signal is measured. However, due to the existence of related parameter interference, the measurement accuracy is low. The differential mode interference and the common mode interference are separated to obtain the corresponding values. The second is the modal separation. The zone is integrated with a central axis and a relatively simple RF transformer as the core to measure the modal signals to improve the network. The recognition performance, but due to the attenuation of 10-20DB, for this, it is necessary to further improve the performance of the separation network.
4 Comparison of experimental characteristics of the separation network
Here, four kinds of separate networks are taken as an example to illustrate, namely, SEE, PAUL, GUO, MARDIGUIAN, etc., for the experimental study of network characteristics.
Through the above devices, the experimental comparison of the four characteristic networks shows that the network characteristics will be attenuated to different degrees with the increase of the frequency. At the same time, the loss will be reduced, and the corresponding suppression ratio characteristics will be greatly reduced. The decline, the zone is integrated, but in engineering applications, when the highest frequency is reached, the difference between the insertion loss characteristic and the suppression characteristic can be maintained at 20DB, and the effective precision is controlled by the separation, based on the small spurious effect, and The layout of the circuit device further distinguishes its good characteristics.
5 Simulation analysis
Here, the GUO and PAUL networks are taken as an example for further research. The SPICE software is used for circuit simulation analysis. In the above analysis, according to the experimental results, it can be known that as the frequency increases, the network characteristics will also have different degrees of attenuation. At the same time, the loss will be reduced, and the corresponding suppression ratio characteristic will be greatly reduced. However, in engineering applications, the CMRR characteristic decreases the fastest. When the highest frequency is reached, the difference between the insertion loss characteristic and the suppression characteristic It can be maintained at 20DB. By effectively separating and controlling the engineering accuracy requirements, it will affect the network performance. At the same time, under the corresponding test conditions, the performance of the network can also be analyzed.
6 application examples
In a solution to the problem of conducted noise, noise separation network is needed to measure noise. In various noise networks, the structure of the MARDIGUIAN separation network is relatively simple, using LCD display, with self-test and the highest precision can reach 1.5DB. However, due to the existence of parasitic capacitance and the output characteristics of the interference differential mode, the common model noise is affected, which increases the common mode rejection ratio of the separation network. At the same time, based on the current characteristics and the interference voltage, the modern experiment is utilized. The equipment uses the principle of stable network and uses noise diagnosis technology for analysis. For this reason, in the scheme, the network that can be selected is optimized network, SEE network, PAUL network, etc. The selected filter has RC, filter, T Type, L type, etc., according to the weight of the index, further refinement processing, and on this basis, through the analytical and descriptive analysis of the decision model, comprehensive consideration of environmental, technical, development and economic factors , computer system and system auxiliary equipment for integrated processing of conducted noise, mainly divided into digital circuit modules , analog circuit module, power module, etc., select different signals, combined with the analysis function of the decision system, to obtain differential mode signals and common mode signals, and use high-speed RAM routine data storage, and finally transmitted to the PC, and the control The method can also be used for various aspects such as environmental noise, quality control, noise engineering, health control, such as office, factory, audio, traffic road, and noise measurement.
7 Conclusion
All in all, the model is based on the case analysis and scanning model established by GONCALVES. It analyzes a certain area, adaptively processes the noise, and compares the four characteristic networks through the above device. The dispersion effect is further distinguished from the layout of the circuit device by its layout.
1 Research background
In practice, a large number of problems exist due to conductive electromagnetic interference, and they are not well solved. EMC standards can be enforced in various countries. Therefore, how to diagnose and control electromagnetic interference noise and establish economic and technological integration Intelligent processing systems have become a hot issue in current research. To this end, relevant experts have established a decision-making parameter model for the diagnosis and processing of noise. By analyzing the analytical and descriptive models of decision-making models, taking into account various factors such as environment, technology, development and economy, it is important to propose a decision-making system. At the same time, the model is based on the case analysis and scanning model established by GONCALVES. It analyzes a certain field and adaptively processes the noise.2 Theoretical analysis
In various noise networks, the structure of the MARDIGUIAN separation network is relatively simple, but due to the existence of parasitic capacitance and the output characteristics of the interference differential mode, the common model noise is affected, resulting in an increase in the common mode rejection ratio of the separation network. .
3 noise diagnosis
Based on current characteristics and interference voltage, using modern experimental equipment, using the principle of stable network, using noise diagnosis technology for analysis, in general, in actual work, because the mechanism of interference is different, then in actual suppression The method will be different. The following are mainly used. The first is the RF radio wave probe. According to the Faraday principle, the interference current signal is measured. However, due to the existence of related parameter interference, the measurement accuracy is low. The differential mode interference and the common mode interference are separated to obtain the corresponding values. The second is the modal separation. The zone is integrated with a central axis and a relatively simple RF transformer as the core to measure the modal signals to improve the network. The recognition performance, but due to the attenuation of 10-20DB, for this, it is necessary to further improve the performance of the separation network.
Conductive electromagnetic interference noise integrated solution
4 Comparison of experimental characteristics of the separation network
Here, four kinds of separate networks are taken as an example to illustrate, namely, SEE, PAUL, GUO, MARDIGUIAN, etc., for the experimental study of network characteristics.
Through the above devices, the experimental comparison of the four characteristic networks shows that the network characteristics will be attenuated to different degrees with the increase of the frequency. At the same time, the loss will be reduced, and the corresponding suppression ratio characteristics will be greatly reduced. The decline, the zone is integrated, but in engineering applications, when the highest frequency is reached, the difference between the insertion loss characteristic and the suppression characteristic can be maintained at 20DB, and the effective precision is controlled by the separation, based on the small spurious effect, and The layout of the circuit device further distinguishes its good characteristics.
5 Simulation analysis
Here, the GUO and PAUL networks are taken as an example for further research. The SPICE software is used for circuit simulation analysis. In the above analysis, according to the experimental results, it can be known that as the frequency increases, the network characteristics will also have different degrees of attenuation. At the same time, the loss will be reduced, and the corresponding suppression ratio characteristic will be greatly reduced. However, in engineering applications, the CMRR characteristic decreases the fastest. When the highest frequency is reached, the difference between the insertion loss characteristic and the suppression characteristic It can be maintained at 20DB. By effectively separating and controlling the engineering accuracy requirements, it will affect the network performance. At the same time, under the corresponding test conditions, the performance of the network can also be analyzed.
6 application examples
In a solution to the problem of conducted noise, noise separation network is needed to measure noise. In various noise networks, the structure of the MARDIGUIAN separation network is relatively simple, using LCD display, with self-test and the highest precision can reach 1.5DB. However, due to the existence of parasitic capacitance and the output characteristics of the interference differential mode, the common model noise is affected, which increases the common mode rejection ratio of the separation network. At the same time, based on the current characteristics and the interference voltage, the modern experiment is utilized. The equipment uses the principle of stable network and uses noise diagnosis technology for analysis. For this reason, in the scheme, the network that can be selected is optimized network, SEE network, PAUL network, etc. The selected filter has RC, filter, T Type, L type, etc., according to the weight of the index, further refinement processing, and on this basis, through the analytical and descriptive analysis of the decision model, comprehensive consideration of environmental, technical, development and economic factors , computer system and system auxiliary equipment for integrated processing of conducted noise, mainly divided into digital circuit modules , analog circuit module, power module, etc., select different signals, combined with the analysis function of the decision system, to obtain differential mode signals and common mode signals, and use high-speed RAM routine data storage, and finally transmitted to the PC, and the control The method can also be used for various aspects such as environmental noise, quality control, noise engineering, health control, such as office, factory, audio, traffic road, and noise measurement.
7 Conclusion
All in all, the model is based on the case analysis and scanning model established by GONCALVES. It analyzes a certain area, adaptively processes the noise, and compares the four characteristic networks through the above device. The dispersion effect is further distinguished from the layout of the circuit device by its layout.
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