Insulated active EMI filter

Abstract

The invention discloses an insulated active EMI filter, and belongs to the technical field of electromagnetic compatibility. Comprising an EMI filter circuit, a connection noise detection circuit and a signal generation circuit. The EMI filter circuit comprises an EMI filter; the EMI filter comprises a magnetic core structure, the magnetic core structure comprises a magnetic core, and a plurality of heat dissipation channels are arranged on the magnetic core structure; an intelligent control unit is arranged in the EMI filter; circuits and power lines are provided with double-layer insulation structures; the noise detection circuit is used for monitoring noise signals in real time; the signal generation circuit is used for generating a compensation signal which is opposite to the noise signal in phase and equal to the noise signal in amplitude, and injecting the compensation signal to a power line through differential amplification to realize active offset of the noise signal; and the intelligent control unit is used for automatically adjusting the intensity and frequency of the compensation signal according to the load condition and the noise signal, and carrying out overvoltage and overcurrent protection at the same time. The magnetic saturation phenomenon is effectively avoided, and the noise reduction performance of the filter is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic compatibility, and particularly relates to an insulation type active EMI filter. BACKGROUND

[0002] When a traditional common mode choke filter is used to deal with electromagnetic interference (EMI) of a high-power / high-current electrical system, the noise reduction effect is greatly reduced due to magnetic saturation. In order to overcome this problem, a multi-stage filter or a high-performance choke coil is usually used, but this not only increases the cost, but also increases the volume and heat of the filter. In the prior art, how to effectively prevent magnetic saturation and maintain insulation performance in high-power applications has become a technical problem. The existing EMI filter structure also has the problem that the circuit elements and the power line are not insulated, which affects the stability and reliability of the EOS resistance. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide an insulation type active EMI filter.

[0004] The purpose of the present application is achieved by the following technical scheme: an insulation type active EMI filter, comprising an EMI filter circuit, the EMI filter circuit is connected to a noise detection circuit and a signal generation circuit; the EMI filter circuit comprises an EMI filter; the EMI filter comprises a magnetic core structure, the magnetic core structure comprises a magnetic core, a plurality of heat dissipation channels are provided on the magnetic core structure, the magnetic permeability of the magnetic core is less than a preset magnetic permeability, and the saturation magnetic flux density of the magnetic core is greater than a preset saturation magnetic flux density; the EMI filter is built-in with an intelligent control unit; the EMI filter circuit, the noise detection circuit, the signal generation circuit and the power line are provided with a double-layer insulation structure; the noise detection circuit is used for real-time monitoring of a noise signal; the signal generation circuit is used for generating a compensation signal which is opposite in phase and equal in amplitude to the noise signal, and the compensation signal is injected into the power line through differential amplification to realize active cancellation of the noise signal; the intelligent control unit is used for automatically adjusting the strength and frequency of the compensation signal according to the load condition and the noise signal, and simultaneously performing overvoltage and overcurrent protection.

[0005] Preferably, the EMI filter circuit further comprises: a common mode choke coil unit, the common mode choke coil unit is arranged on the power side and is connected to the live wire and the neutral wire of the EMI source and has windings wound thereon; a Y capacitor, the Y capacitor is arranged on the EMI source side and is composed of two series-connected capacitors, the two capacitors are connected in parallel between the live wire and the neutral wire and are commonly connected to the ground; a sensing winding unit, the sensing winding unit is re-wound on the common mode choke coil unit by a coil and senses the noise current of the common mode choke coil unit. An amplification unit is used to amplify the noise current sensed by the sensing winding unit; A transformer unit is disposed at the front end of the Y capacitor. The primary coil receives the amplified signal from the amplification unit, and the secondary coil is connected to ground connected to the Y capacitor to isolate it from the power supply line. The signal of the secondary coil is injected into the Y capacitor as a compensation signal.

[0006] Preferably, the double-layer insulation structure includes an outer layer structure and an inner layer structure. The outer layer structure uses an insulating material with a temperature resistance rating greater than a preset rating and an insulation strength greater than a preset strength. The inner layer structure uses a conductive material with a resistivity lower than a preset resistivity and a thermal conductivity greater than a preset coefficient.

[0007] Preferably, the insulating material is a ceramic matrix composite material or a special plastic.

[0008] Preferably, the conductive material is a metal or alloy.

[0009] The beneficial effects of this invention are: 1) Through active noise cancellation mechanism and optimized magnetic core design, the present invention effectively avoids magnetic saturation and significantly improves the noise reduction performance of the filter, which is especially suitable for high power / high current electrical systems.

[0010] 2) Compared with traditional multi-stage filters or high-performance choke solutions, this invention uses fewer chokes, which reduces cost and size while achieving efficient noise reduction.

[0011] 3) The double-layer insulation structure design ensures complete isolation between the active circuit components and the power line, improving electrical insulation performance; at the same time, the intelligent control unit has overvoltage and overcurrent protection functions, enhancing the filter's anti-EOS stability and reliability.

[0012] 4) The optimized magnetic core structure and heat dissipation design ensure good heat dissipation performance of the filter under high load, prevent overheating damage, and extend service life. Attached Figure Description

[0013] Fig. 1 This is a block diagram of an insulated active EMI filter. Fig. 2 This is a schematic diagram of an EMI filter circuit. Detailed Implementation

[0014] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0015] See Figs. 1-2 This invention provides a technical solution: an insulated active EMI filter, including an EMI filter circuit connected to a noise detection circuit and a signal generation circuit; the EMI filter circuit includes an EMI filter; the EMI filter includes a magnetic core structure, the magnetic core structure including a magnetic core, the magnetic core structure having multiple heat dissipation channels, the magnetic permeability of the magnetic core being less than a preset magnetic permeability, and the saturation magnetic flux density of the magnetic core being greater than a preset saturation magnetic flux density; the EMI filter has a built-in intelligent control unit; the EMI filter circuit, noise detection circuit, signal generation circuit, and power line are provided with a double-layer insulation structure; the noise detection circuit is used to monitor noise signals in real time; the signal generation circuit is used to generate a compensation signal with opposite phase and equal amplitude to the noise signal, and injects the compensation signal into the power line through differential amplification to achieve active cancellation of the noise signal; the intelligent control unit is used to automatically adjust the strength and frequency of the compensation signal according to the load and noise signal, while performing overvoltage and overcurrent protection.

[0016] In this embodiment, a double-layer insulation structure is employed to completely isolate the active circuit components from the power line, ensuring electrical insulation performance. The outer layer uses high-temperature resistant, high-insulation-strength materials, such as ceramic matrix composites or special plastics, while the inner layer uses low-resistivity, high-thermal-conductivity metals or alloys as the conductive layer, ensuring both insulation and conductivity efficiency. The filter incorporates a high-precision noise detection circuit and a signal generation circuit, capable of real-time monitoring and generating a compensation signal with opposite phase and equal amplitude to the noise signal. This compensation signal is injected into the power line using differential amplification technology, achieving active noise cancellation. This mechanism effectively avoids magnetic saturation and improves noise reduction performance. For high-power / high-current applications, this invention uses a magnetic powder core material with low permeability and high saturation magnetic flux density to reduce the risk of magnetic saturation. Simultaneously, the core structure design incorporates sufficient heat dissipation channels, combined with external heat sinks or fans, ensuring the filter maintains good heat dissipation performance under high loads and preventing overheating damage. The filter incorporates an intelligent control unit that automatically adjusts the strength and frequency of the compensation signal according to the actual load and noise level, achieving dynamic optimization of the noise reduction effect. Meanwhile, the control unit also has overvoltage and overcurrent protection functions, improving the filter's resistance to EOS.

[0017] In some embodiments, the EMI filter circuit further includes: A common-mode choke unit is disposed on the power supply side, and the live wire and neutral wire connected to the EMI source are respectively wound with windings. The Y capacitor, located on the EMI source side, consists of two capacitors connected in series. The two capacitors are connected in parallel between the live wire and the neutral wire, and are also connected to the ground. A sensing winding unit, wherein the sensing winding unit is rewound on the common mode choke unit via a coil, and senses the noise current of the common mode choke unit; An amplification unit is used to amplify the noise current sensed by the sensing winding unit; A transformer unit is disposed at the front end of the Y capacitor. The primary coil receives the amplified signal from the amplification unit, and the secondary coil is connected to ground connected to the Y capacitor to isolate it from the power supply line. The signal of the secondary coil is injected into the Y capacitor as a compensation signal.

[0018] In some embodiments, the double-layer insulation structure includes an outer layer structure and an inner layer structure. The outer layer structure uses an insulating material with a temperature resistance rating greater than a preset rating and an insulation strength greater than a preset strength. The inner layer structure uses a conductive material with a resistivity lower than a preset resistivity and a thermal conductivity greater than a preset coefficient.

[0019] In some embodiments, the insulating material is a ceramic matrix composite material or a special plastic.

[0020] In some embodiments, the conductive material is a metal or alloy.

[0021] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. An isolation type active EMI filter, characterized by: The EMI filter circuit comprises a noise detection circuit and a signal generation circuit, and the EMI filter circuit comprises an EMI filter; the EMI filter comprises a magnetic core structure, the magnetic core structure comprises a magnetic core, a plurality of heat dissipation channels are arranged on the magnetic core structure, the magnetic permeability of the magnetic core is less than a preset magnetic permeability, and the saturation magnetic flux density of the magnetic core is greater than a preset saturation magnetic flux density; the EMI filter is internally provided with an intelligent control unit; the EMI filter circuit, the noise detection circuit, the signal generation circuit and a power line are provided with a double-layer insulation structure; the noise detection circuit is used for monitoring a noise signal in real time; the signal generation circuit is used for generating a compensation signal which is opposite in phase and equal in amplitude to the noise signal, injecting the compensation signal into the power line through differential amplification, and actively canceling the noise signal; and the intelligent control unit is used for automatically adjusting the strength and frequency of the compensation signal according to a load condition and the noise signal, and simultaneously performing overvoltage and overcurrent protection.

2. The isolation-mode active EMI filter of claim 1, wherein: The EMI filter circuit further comprises: A common-mode choke unit, which is arranged on the power supply side and has windings wound around the live wire and the neutral wire of the EMI source respectively; A Y capacitor, which is arranged on the EMI source side and comprises two series-connected capacitors, the two capacitors being connected in parallel between the live wire and the neutral wire and being connected to the ground together; A sensing winding unit, which is wound on the common-mode choke unit by a coil and senses the noise current of the common-mode choke unit; An amplification unit, which is used for amplifying the noise current sensed by the sensing winding unit; A transformer unit, which is arranged at the front end of the Y capacitor, a primary coil of the transformer unit receiving an amplified signal from the amplification unit, a secondary coil of the transformer unit being connected to the ground connected to the Y capacitor so as to be isolated from the power line, and a signal of the secondary coil being injected into the Y capacitor as a compensation signal.

3. The isolation-mode active EMI filter of claim 1 or 2, wherein: The double-layer insulation structure comprises an outer layer structure and an inner layer structure, the outer layer structure uses an insulating material with a temperature resistance greater than a preset temperature resistance and an insulation strength greater than a preset insulation strength, and the inner layer structure uses a conductive material with an electrical resistivity lower than a preset electrical resistivity and a thermal conductivity coefficient greater than a preset thermal conductivity coefficient.

4. The isolation-mode active EMI filter of claim 3, wherein: The insulating material is a ceramic matrix composite material or a special plastic.

5. The isolation-mode active EMI filter of claim 3, wherein: The conductive material is a metal or an alloy material.

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