Adaptive adjustable noise source impedance EMI filtering device and method

Abstract

The invention provides a self-adaptive noise source impedance adjustable EMI filtering device and method, and belongs to the field of electromagnetic interference processing. The device comprises an EMI filter, a coupling inductor, a balance winding, a balance impedance, a balance impedance adjusting module and a self-adaptive control module; the coupling inductor, the EMI filter and the balance winding form a six-port network, and the self-adaptive control module is used for converting the six-port network into a four-port network according to scattering parameters of the six-port network, constructing a mixed-mode common-mode parameter matrix, obtaining an initial common-mode reflection coefficient according to the mixed-mode common-mode parameter matrix, and outputting the initial common-mode reflection coefficient. And based on the initial common-mode reflection coefficient and a preset target reflection coefficient, obtaining a balance impedance adjustment direction and a balance impedance adjustment amplitude which meet preset requirements so as to control an impedance adjustment module to dynamically adjust the balance impedance. According to the invention, the balance impedance is optimized and adjusted in real time to cope with the dynamic change working condition of the circuit, and the EMI filtering performance reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic interference processing, and in particular to an EMI filtering device and method with adaptively adjustable noise source impedance. Background Art

[0002] With the increasing sophistication and miniaturization of intelligent control devices, the density of internal electronic components and circuits has increased significantly. Therefore, how to solve the problem of electromagnetic interference between electronic components and circuits has become a technical key in this field.

[0003] Currently, the most commonly used method in existing technologies is to add EMI filters to the circuit. However, in traditional filters, the measurement of noise source impedance and filter design are usually independent links, which cannot form a unified organic whole. In the noise source impedance measurement link, the interference of many factors such as parasitic parameters and PCB layout makes it difficult to accurately measure the noise source impedance in one go. Manual intervention is often required to continuously adjust the EMI filter design parameters. As a result, the technical means of the existing technology cannot effectively cope with the changing circuit operating conditions, resulting in the problem of poor reliability of EMI filtering performance. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes an EMI filtering device and method with adaptively adjustable noise source impedance, which can realize real-time optimization and adjustment of the balanced impedance to cope with the dynamic changes in the circuit working conditions and improve the reliability of EMI filtering performance.

[0005] To achieve the above-mentioned purpose, an embodiment of the present invention provides an EMI filtering device with adaptive adjustable noise source impedance, comprising: an EMI filter, a coupled inductor, a balanced winding, a balanced impedance, a balanced impedance adjustment module, a noise spectrum real-time monitoring module and an adaptive control module; the EMI filter is electrically connected to the coupled inductor, and the coupled inductor, the EMI filter and the balanced winding constitute a six-port network; the balanced winding lead-out port is connected in series with the balanced impedance, the impedance adjustment module is electrically connected to the balanced winding lead-out port, the noise spectrum real-time monitoring module is electrically connected to the EMI filter output port, and the adaptive control module is electrically connected to the six-port network, the impedance adjustment module and the noise spectrum real-time monitoring module; the balanced impedance The adjustment module is used to dynamically adjust the balanced impedance; the noise spectrum real-time monitoring module is used to detect the common-mode noise spectrum of the EMI filter output port, and determine whether the common-mode noise spectrum of the EMI filter output port meets the preset filter design requirements, and obtain the six-port network scattering parameters; the adaptive control module is used to convert the six-port network into a four-port network according to the six-port network scattering parameters and construct a mixed-mode common-mode parameter matrix, and obtain the initial common-mode reflection coefficient according to the mixed-mode common-mode parameter matrix. Based on the initial common-mode reflection coefficient and the preset target reflection coefficient, the balanced impedance adjustment direction and balanced impedance adjustment amplitude that meet the preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance.

[0006] An embodiment of the present invention provides an EMI filtering device with adaptively adjustable noise source impedance. A six-port network is formed by an EMI filter, a coupled inductor, and a balanced winding. The common-mode noise spectrum of the EMI filter output port can be monitored in real time by a noise spectrum real-time monitoring module to obtain the scattering coefficient of the six-port network. Since the six-port network is not a standard differential structure, a balanced impedance is connected in series at the balanced winding lead port to reduce the number of ports. Then, based on the scattering coefficient of the six-port network, the six-port network is converted into a four-port network with a differential structure. A mixed-mode common-mode parameter matrix is separated from the four-port network and an initial common-mode reflection coefficient is calculated. The balanced impedance is dynamically adjusted by comparing with a preset target reflection coefficient. In this way, when the circuit operating condition changes, the change in the scattering coefficient of the six-port network is monitored, and the mixed-mode common-mode parameter matrix is quickly updated and compared with the preset target reflection coefficient to adjust the balanced impedance, thereby improving the reliability of the EMI filtering performance.

[0007] Furthermore, the EMI filter is electrically connected to the coupled inductor, including: the coupled inductor adopts two discrete inductors, the two discrete inductors are respectively wound on two side columns of a preset magnetic core, and the central column of the preset magnetic core is provided with an air gap; the EMI filter electrical connection port is led out from the coupled inductors on the two side columns of the preset magnetic core to electrically connect the EMI filter to the coupled inductor.

[0008] Through the above solution, two discrete inductors are wound on the two side legs of the magnetic core, and an air gap is opened in the center leg of the magnetic core. This can reduce the risk of core saturation and obtain more stable inductance characteristics under high-frequency or transient conditions, thereby improving the reliability of EMI filtering performance.

[0009] Furthermore, the balanced winding lead-out port is connected in series with the balanced impedance, including: the balanced winding is wound on two side columns of the preset magnetic core and does not pass through the center column of the preset magnetic core, and the balanced winding is in an "8" shape; based on the balanced winding on any one side column of the preset magnetic core, the balanced winding lead-out port is led out and connected in series with the balanced impedance.

[0010] Through the above scheme, the balance winding is wound in an "8" shape on the side column without passing through the center column. The balance impedance is connected in series to the balance winding lead-out port. When the circuit operating conditions change and the common-mode noise source impedance shifts, the balance winding changes the magnetic flux distribution in the magnetic core by adjusting the balance impedance, and synergistically adjusts the equivalent common-mode impedance of the coupled inductor, thereby improving the reliability of EMI filtering performance.

[0011] Furthermore, the adaptive control module is used to convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix based on the scattering parameters of the six-port network. According to the mixed-mode common-mode parameter matrix, an initial common-mode reflection coefficient is obtained. Based on the initial common-mode reflection coefficient and the preset target reflection coefficient, a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance, including: obtaining the six-port network scattering parameters based on a preset impedance analysis algorithm; calculating the balanced winding lead-out port impedance based on the six-port network scattering parameters; converting the six-port network into a four-port network based on the balanced winding lead-out port impedance, and obtaining the mixed-mode scattering parameters; and obtaining the mixed-mode common-mode parameter matrix based on the mixed-mode scattering parameters.

[0012] Through the above scheme, according to the preset impedance analysis algorithm, the scattering parameters of the six-port network are measured in real time. The scattering parameters of the six-port network describe the transmission and reflection characteristics of the network at different frequencies. According to the scattering parameters of the six-port network, a rapid response to the circuit operating conditions is made. Since the six-port network is not a standard differential structure, a balanced impedance is connected in series at the balanced winding lead-out port and the impedance of the balanced winding lead-out port is calculated to reduce the number of ports. The six-port network is thus converted into a four-port network with a differential structure, and the mixed-mode scattering parameters are obtained, which reduces the dimension of parameter analysis. Then, the mixed-mode common-mode parameter matrix is separated according to the mixed-mode scattering parameters. The mixed-mode common-mode parameter matrix can be used to calculate key indicators such as equivalent common-mode impedance and common-mode insertion loss. When the circuit operating conditions change, the changes in the scattering coefficient of the six-port network are monitored, and the mixed-mode common-mode parameter matrix is quickly updated, providing a data basis for subsequent adjustment of the balanced impedance, thereby improving the reliability of EMI filtering performance.

[0013] Furthermore, based on the six-port network scattering parameters, the balanced winding lead-out port impedance is calculated, including: obtaining the balanced winding lead-out port reflection coefficient based on the six-port network scattering parameters and the balanced impedance; and obtaining the balanced winding lead-out port impedance based on the balanced winding lead-out port reflection coefficient and a preset characteristic impedance.

[0014] Through the above scheme, since the six-port network is not a standard differential structure, a balanced impedance is connected in series with the balanced winding lead-out port and the balanced winding lead-out port impedance is calculated, so that the balanced winding lead-out port is equivalent to the balanced winding lead-out port impedance, reducing the number of ports to realize the conversion of the six-port network into a four-port network, thereby improving the reliability of EMI filtering performance.

[0015] Furthermore, the adaptive control module is used to convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix based on the scattering parameters of the six-port network, obtain an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix, and obtain a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to control the impedance adjustment module to dynamically adjust the balanced impedance, including: initializing the balanced impedance to obtain an initial balanced impedance; obtaining an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix and a preset common-mode characteristic impedance; calculating the insertion loss based on the initial common-mode reflection coefficient; calculating the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude based on the initial common-mode reflection coefficient and the preset target reflection coefficient; updating the initial balanced impedance based on a preset gradient optimization algorithm until the insertion loss meets a preset convergence condition, and obtaining a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements, so as to control the impedance adjustment module to dynamically adjust the balanced impedance.

[0016] Through the above scheme, the balanced impedance is initialized, and then the six-port network is converted into a four-port network and the separated mixed-mode common-mode parameter matrix is used to calculate the initial common-mode reflection coefficient and insertion loss. The initial common-mode reflection coefficient is then compared with the preset target reflection coefficient to obtain the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude. Through the preset gradient optimization algorithm, the initial balanced impedance is dynamically adjusted until the insertion loss meets the preset convergence condition, and the balanced impedance adjustment direction and the balanced impedance adjustment amplitude that meet the preset requirements are obtained. The balanced impedance is adjusted in this way. When the circuit operating conditions change, the common-mode insertion loss is optimized according to the updated value of the mixed-mode common-mode parameter matrix, so as to realize real-time dynamic adjustment of the balanced impedance and improve the reliability of EMI filtering performance.

[0017] Furthermore, based on the mixed mode common mode parameter matrix and the preset common mode characteristic impedance, an initial common mode reflection coefficient is obtained, including: obtaining a first equivalent impedance based on the mixed mode common mode parameter matrix and the preset common mode characteristic impedance; and obtaining an initial common mode reflection coefficient based on the preset second equivalent impedance, the first equivalent impedance and the preset characteristic impedance.

[0018] Through the above scheme, the preset common-mode characteristic impedance is matched by the existing characteristic matching principle, and then combined with the mixed-mode common-mode parameter matrix, the first equivalent impedance is calculated, and then the initial common-mode reflection coefficient is obtained based on the preset second equivalent impedance, the first equivalent impedance and the preset characteristic impedance. The impedance relationship of the entire EMI filtering device is reflected by calculating the reflection coefficient, which is subsequently reflected as the common-mode insertion loss, and then the performance of the entire EMI filtering device is reflected, providing a data basis for the subsequent dynamic adjustment of the balanced impedance, and improving the reliability of the EMI filtering performance.

[0019] Furthermore, the balanced impedance adjustment module is composed of a digitally controlled resistor array, which is used to dynamically adjust the balanced impedance, including: the digital communication interface of the digitally controlled resistor array is electrically connected to the adaptive control module, and the digital communication interface of the digitally controlled resistor array receives and executes the balanced impedance adjustment control signal sent by the adaptive control module.

[0020] Through the above scheme, the balanced impedance adjustment module is composed of a digitally controlled resistor array, and the digital communication interface is electrically connected to the adaptive control module. It can receive and execute the balanced impedance adjustment control signal sent by the adaptive control module, and realize continuous or discrete step-by-step adjustment within the resistance range, ensuring flexible adjustment of the balanced impedance within a wide common-mode frequency band, thereby improving the reliability of EMI filtering performance.

[0021] An embodiment of the present invention also provides an EMI filtering method with adaptively adjustable noise source impedance, comprising: obtaining scattering parameters of a six-port network based on a preset impedance analysis algorithm; converting the six-port network into a four-port network and constructing a mixed-mode common-mode parameter matrix based on the six-port network scattering parameters; obtaining an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix; and obtaining a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to dynamically adjust the balanced impedance.

[0022] An embodiment of the present invention proposes an EMI filtering method with adaptively adjustable noise source impedance. The method obtains a scattering coefficient of a six-port network by real-time monitoring of the common-mode noise spectrum of the EMI filter output port. Then, based on the scattering coefficient of the six-port network, the six-port network is converted into a four-port network with a differential structure. A mixed-mode common-mode parameter matrix is separated from the four-port network and an initial common-mode reflection coefficient is calculated. The balanced impedance is dynamically adjusted by comparing with a preset target reflection coefficient. In this way, when the circuit operating condition changes, the change of the scattering coefficient of the six-port network is monitored, and the mixed-mode common-mode parameter matrix is quickly updated and compared with the preset target reflection coefficient to adjust the balanced impedance, thereby improving the reliability of EMI filtering performance.

[0023] Furthermore, based on the initial common-mode reflection coefficient and the preset target reflection coefficient, a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet the preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance, including: initializing the balanced impedance to obtain the initial balanced impedance; calculating the insertion loss based on the initial common-mode reflection coefficient; calculating the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude based on the initial common-mode reflection coefficient and the preset target reflection coefficient; based on the preset gradient optimization algorithm, updating the initial balanced impedance until the insertion loss meets the preset convergence condition, and obtaining the balanced impedance adjustment direction and the balanced impedance adjustment amplitude that meet the preset requirements to control the impedance adjustment module to dynamically adjust the balanced impedance.

[0024] Through the above scheme, the balanced impedance is initialized, and then the six-port network is converted into a four-port network and the separated mixed-mode common-mode parameter matrix is used to calculate the initial common-mode reflection coefficient and insertion loss. The initial common-mode reflection coefficient is then compared with the preset target reflection coefficient to obtain the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude. Through the preset gradient optimization algorithm, the initial balanced impedance is dynamically adjusted until the insertion loss meets the preset convergence condition, and the balanced impedance adjustment direction and the balanced impedance adjustment amplitude that meet the preset requirements are obtained. The balanced impedance is adjusted in this way. When the circuit operating conditions change, the differential-mode insertion loss is optimized according to the updated value of the mixed-mode common-mode parameter matrix, so as to realize real-time dynamic adjustment of the balanced impedance and improve the reliability of EMI filtering performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 1 ;

[0026] Figure 2 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ;

[0027] Figure 3 Schematic diagram of an equivalent circuit of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 1 ;

[0028] Figure 4 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 3 ;

[0029] Figure 5 Schematic diagram of an equivalent circuit of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ;

[0030] Figure 6 A schematic flow chart of the steps of an EMI filtering method with adaptively adjustable noise source impedance provided by an embodiment of the present invention;

[0031] Figure 7 A schematic diagram of the original noise of an EMI filtering method with adaptively adjustable noise source impedance provided by an embodiment of the present invention;

[0032] Figure 8 A comparison diagram of a conventional fixed-impedance EMI filter before and after noise optimization using an EMI filtering method with adaptively adjustable noise source impedance provided by one embodiment of the present invention;

[0033] Figure 9 A comparison diagram before and after noise optimization of an EMI filtering device with an adaptively adjustable noise source impedance according to an EMI filtering method with an adaptively adjustable noise source impedance provided by one embodiment of the present invention;

[0034] Figure numerals: 11, EMI filter; 12, coupled inductor; 13, balanced winding; Rb, balanced impedance; 14, balanced impedance adjustment module; 15, noise spectrum real-time monitoring module; 16, adaptive control module; 17, magnetic core. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Example 1

[0037] See also Figure 1 , Figure 1A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 1 .like Figure 1 As shown, the embodiment of the present invention proposes an EMI filtering device with adaptive adjustable noise source impedance, comprising: an EMI filter 11, a coupled inductor 12, a balanced winding 13, a balanced impedance Rb, a balanced impedance adjustment module 14, a noise spectrum real-time monitoring module 15 and an adaptive control module 16; the EMI filter 11 is electrically connected to the coupled inductor 12, and the coupled inductor 12, the EMI filter 11 and the balanced winding 13 form a six-port network; the balanced winding lead-out port is connected in series with the balanced impedance Rb, the impedance adjustment module is electrically connected to the balanced winding lead-out port, the noise spectrum real-time monitoring module 15 is electrically connected to the EMI filter output port, and the adaptive control module 16 is connected to the six-port network, the impedance adjustment module and the noise spectrum real-time monitoring module 15. Electrical connection; the balanced impedance adjustment module 14 is used to dynamically adjust the balanced impedance Rb; the noise spectrum real-time monitoring module 15 is used to detect the common-mode noise spectrum of the EMI filter output port, and determine whether the common-mode noise spectrum of the EMI filter output port meets the preset filter design requirements, and obtain the six-port network scattering parameters; the adaptive control module 16 is used to convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix according to the six-port network scattering parameters, and obtain the initial common-mode reflection coefficient according to the mixed-mode common-mode parameter matrix. Based on the initial common-mode reflection coefficient and the preset target reflection coefficient, the balanced impedance adjustment direction and balanced impedance adjustment amplitude that meet the preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance Rb.

[0038] For a specific implementation method, see Figure 1The embodiment of the present invention proposes an EMI filtering device with adaptive adjustable noise source impedance, comprising: an EMI filter 11, a coupled inductor 12, a balanced winding 13, a balanced impedance Rb, a balanced impedance adjustment module 14, a noise spectrum real-time monitoring module 15 and an adaptive control module 16. The EMI filter 11 is electrically connected to the coupled inductor 12. The six-port network includes: the coupled inductor 12, the balanced winding 13 and four ports (1-4) of the EMI filter 11, and two lead ports (5-6) of the balanced winding 13; the two lead ports (5-6) of the balanced winding 13 are connected in series with the balanced impedance Rb, and the impedance adjustment module is electrically connected to the balanced winding lead port (5-6) to adjust the balanced impedance Rb. It is mentioned that the resistance of the impedance adjustment module can be continuously or discretely adjusted in a step-by-step manner within the range of 10Ω to 10kΩ, and the step resolution is not greater than 1Ω, so as to ensure that the noise source impedance can be flexibly changed within a wide common-mode frequency band. The noise spectrum real-time monitoring module 15 is electrically connected to the EMI filter output port and can monitor the noise spectrum at the output end of the EMI filter device in real time. The implementation method of the noise spectrum real-time monitoring module 15 includes: placing a high-frequency test interface or sensor at the EMI filter output port to capture and display the spectrum distribution of electromagnetic interference, especially the high-frequency components related to the noise source. After the noise spectrum is collected, it is compared with the preset filter design standard (such as the noise limit is 65dB, which may be different under different design standards, and the specific limit value may be different under different circumstances). The noise spectrum of the EMI filter output port meets the limit requirements, which means that the filter meets the design standards. In order to quantitatively characterize the matching relationship between the noise source port and the filter port, the noise spectrum real-time monitoring module 15 also cooperates with a network analyzer or a high-speed data acquisition system to measure the scattering parameters of the six-port network. The adaptive control module 16 is electrically connected to the six-port network, the impedance adjustment module and the noise spectrum real-time monitoring module 15. The adaptive control module 16 receives the monitoring data of the six-port network from the noise spectrum real-time monitoring module 15 (feedback is the scattering parameters of the six-port network), converts the six-port network into a four-port network according to the scattering parameters of the six-port network, and extracts the balanced impedance Rb. The relevant mixed-mode common-mode parameter matrix SCC can be used to calculate key indicators such as equivalent common-mode impedance and common-mode insertion loss in the high-frequency range. The real-time six-port network equivalent impedance and the corresponding common-mode reflection coefficient (equivalent to the initial common-mode reflection coefficient) are calculated based on the mixed-mode common-mode parameter matrix SCC, and the set target reflection coefficient or the preset common-mode impedance target (equivalent to the preset target reflection coefficient) are compared, and then a corresponding control signal is generated (equivalent to the balanced impedance adjustment direction and balanced impedance adjustment amplitude that meet the preset requirements) and the corresponding control signal is sent to the balanced impedance adjustment module 14. The balanced impedance adjustment module 14 receives the corresponding control signal and adjusts the balanced winding 13 to achieve adaptive dynamic adjustment of the impedance.

[0039] An embodiment of the present invention provides an EMI filtering device with adaptively adjustable noise source impedance. A six-port network is formed by an EMI filter 11, a coupled inductor 12, and a balanced winding 13. The common-mode noise spectrum of the EMI filter output port can be monitored in real time by a noise spectrum real-time monitoring module 15 to obtain the scattering coefficient of the six-port network. Since the six-port network is not a standard differential structure, a balancing impedance Rb is connected in series at the balanced winding lead port to reduce the number of ports. Then, based on the scattering coefficient of the six-port network, the six-port network is converted into a four-port network with a differential structure. A mixed-mode common-mode parameter matrix is separated from the four-port network and an initial common-mode reflection coefficient is calculated. The balancing impedance Rb is dynamically adjusted by comparing with a preset target reflection coefficient. In this way, when the circuit operating conditions change, the change in the scattering coefficient of the six-port network is monitored, and the mixed-mode common-mode parameter matrix is quickly updated and compared with the preset target reflection coefficient to adjust the balancing impedance Rb, thereby improving the reliability of the EMI filtering performance.

[0040] As an example of an embodiment of the present invention, the EMI filter 11 is electrically connected to the coupled inductor 12, including: the coupled inductor 12 uses two discrete inductors, the two discrete inductors are respectively wound on the two side columns of the preset magnetic core 17, and the central column of the preset magnetic core 17 is provided with an air gap; the EMI filter electrical connection port is led out from the coupled inductor 12 on the two side columns of the preset magnetic core 17 to electrically connect the EMI filter 11 to the coupled inductor 12.

[0041] For a specific implementation method, see Figure 2 , Figure 2 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ;like Figure 2 As shown, the coupled inductor 12 includes: two discrete inductors wound on the two side columns of the EE core 17, and an air gap is opened on the center column of the EE core 17 to reduce the saturation of the core 17 at high frequencies and achieve more stable inductance characteristics. The two discrete inductors are respectively connected to the EMI filter electrical connection ports and the EMI filter 11. The output ends of the EMI filter 11 are port 2 and port 4.

[0042] Through the above scheme, two discrete inductors are wound on the two side columns of the magnetic core 17, and an air gap is opened in the center column of the magnetic core 17. This can reduce the saturation risk of the magnetic core 17 under high frequency or transient conditions and obtain more stable inductance characteristics, thereby improving the reliability of EMI filtering performance. f1 and L f2 The configuration makes the mutual inductance coefficient M between the inductors on both sides satisfy:

[0043]

[0044] This achieves better magnetic coupling characteristics in the high frequency band, suppressing the bias effect of the magnetic core 17 and improving the ability to suppress common mode noise. At the same time, the EMI filter 11 uses an LC filter to preliminarily filter out the conducted electromagnetic interference at the input and output ends of the converter.

[0045] As an example of an embodiment of the present invention, the balanced winding lead-out port is connected in series with the balanced impedance Rb, including: the balanced winding 13 is wound on two side columns of the preset magnetic core 17 and does not pass through the center column of the preset magnetic core 17, and the balanced winding 13 is in an "8" shape; based on the balanced winding 13 on any one side column of the preset magnetic core 17, the balanced winding lead-out port is led out and connected in series with the balanced impedance Rb.

[0046] For a specific implementation method, see Figure 2 , Figure 2 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ;like Figure 2 As shown, a balancing winding 13 is added to the coupled inductor 12, and a balancing impedance Rb is added to the end of the balancing winding 13. Specifically, in the winding process of the two side columns, in addition to the discrete inductor, an additional balancing winding 13 wound in an "8" shape is provided. The winding does not pass through the center column, but leads to two ports (denoted as port 5 and port 6) from the other side column. An adjustable balancing impedance Rb is connected in series between port 5 and port 6, thereby forming an adjustable noise source impedance network.

[0047] Through the above scheme, the balance winding 13 is wound in an "8" shape on the side column and does not pass through the center column. The balance impedance Rb is connected in series to the balance winding lead-out port. When the circuit operating condition changes and causes the common-mode noise source impedance to shift, the balance winding 13 changes the magnetic flux distribution in the magnetic core 17 by adjusting the balance impedance Rb, and coordinately adjusts the equivalent common-mode impedance of the coupled inductor 12, thereby improving the reliability of EMI filtering performance.

[0048] As an example of an embodiment of the present invention, the adaptive control module 16 is used to convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix based on the six-port network scattering parameters, obtain an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix, and obtain a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to control the impedance adjustment module to dynamically adjust the balanced impedance Rb, including: obtaining the six-port network scattering parameters based on a preset impedance analysis algorithm; calculating the balanced winding lead-out port impedance based on the six-port network scattering parameters; converting the six-port network into a four-port network based on the balanced winding lead-out port impedance, and obtaining the mixed-mode scattering parameters; and obtaining the mixed-mode common-mode parameter matrix based on the mixed-mode scattering parameters.

[0049] For a specific implementation method, see Figure 2 , Figure 2 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ;like Figure 2 As shown, the coupled inductor 12 and the balanced winding 13 constitute the impedance adjustment part, and the circuit structure of the impedance adjustment part is as follows: Figure 2 As shown, the impedance adjustment part and the EMI filter 11 form a six-port network, and the scattering parameters (S parameters) are used to describe the six-port network, as shown in FIG. Figure 1 and Figure 2 As shown, port 1, port 2, port 3 and port 4 are the four ports of the coupled inductor 12 and the EMI filter 11, port 5 and port 6 are the two lead-out ports of the balanced winding 13, and the resistor Rb is connected in series between the 5th port and the 6th port as the balancing impedance Rb. The six-port network scattering parameters are obtained by the impedance analyzer (equivalent to the preset impedance analysis algorithm). The six-port network is described by the six-port network scattering parameters. Since the six-port network is not a standard differential structure, it is not easy to analyze it directly. Therefore, the balancing impedance Rb is connected in series between the 5th port and the 6th port, so that the remaining 1-4 ports form a new four-port network. The four-port network and the 5-port network form a new four-port network. It is related to the impedance in series between the 6 ports. According to the impedance mismatch principle, when the balanced impedance Rb is connected in series between the 5-port and 6-port, the power wave is reflected at these two ports. By calculating the impedance values of the 5-port and 6-port containing the balanced impedance Rb (equivalent to the impedance of the balanced winding lead-out port), the six-port network is converted into a four-port network. The four-port network is a standard differential structure. After obtaining the four-port network, the conversion between the differential and common modes is ignored, and the S parameters of the differential mode are converted into the mixed mode. The mixed mode common mode parameter matrix (SCC matrix) related to the balanced impedance Rb can be separated. The SCC matrix includes the S parameters (S 11 、S 12 、S21 and S 22 ).

[0050] Through the above scheme, according to the preset impedance analysis algorithm, the scattering parameters of the six-port network are measured in real time. The scattering parameters of the six-port network describe the transmission and reflection characteristics of the network at different frequencies. According to the scattering parameters of the six-port network, the circuit operating conditions are quickly responded to. Since the six-port network is not a standard differential structure, the balanced impedance Rb is connected in series at the balanced winding lead-out port and the balanced winding lead-out port impedance is calculated to reduce the number of ports. The six-port network is thus converted into a four-port network with a differential structure, and the mixed-mode scattering parameters are obtained, which reduces the dimension of parameter analysis. Then, the mixed-mode common-mode parameter matrix is separated according to the mixed-mode scattering parameters. The mixed-mode common-mode parameter matrix can be used to calculate key indicators such as equivalent common-mode impedance and common-mode insertion loss. When the circuit operating conditions change, the changes in the scattering coefficient of the six-port network are monitored, and the mixed-mode common-mode parameter matrix is quickly updated, providing a data basis for subsequent adjustment of the balanced impedance Rb, thereby improving the reliability of EMI filtering performance.

[0051] As an example of an embodiment of the present invention, the impedance of the balanced winding lead-out port is calculated based on the scattering parameters of the six-port network, including: obtaining the reflection coefficient of the balanced winding lead-out port based on the six-port network scattering parameters and the balanced impedance Rb; and obtaining the impedance of the balanced winding lead-out port based on the reflection coefficient of the balanced winding lead-out port and a preset characteristic impedance.

[0052] In a specific embodiment, the relationship between the reflection coefficient, S parameter and balanced impedance Rb of the 5-port and 6-port is:

[0053]

[0054] Where Γ5 is the reflection coefficient of port 5, Γ6 is the reflection coefficient of port 6, and S 55 、S 56 、S 66 and S 65 are the S parameters of 5-port and 6-port, R b The resistance of the balanced impedance Rb is Z0, which is the characteristic impedance of the system. In circuits and signal transmission, characteristic impedance refers to the ideal impedance value for lossless signal transmission without reflection. The concept of characteristic impedance is often applied to transmission lines (such as coaxial cables or microstrip lines), representing the impedance value of the signal as it propagates along the transmission line. By matching the characteristic impedance of the circuit with the impedance source, energy transfer can be maximized and reflections can be reduced, thereby improving the performance of electromagnetic interference (EMI) filters.

[0055] The impedance values of port 5 and port 6 are further calculated as follows:

[0056] Z5=Z0(1+Γ5) / (1-Γ5);

[0057] Z6=Z0(1+Γ6) / (1-Γ6);

[0058] Where Z5 is the impedance value of port 5, and Z6 is the impedance value of port 6;

[0059] Through the above scheme, since the six-port network is not a standard differential structure, the balanced impedance Rb is connected in series with the balanced winding lead-out port and the balanced winding lead-out port impedance is calculated. In this way, the balanced winding lead-out port is equivalent to the balanced winding lead-out port impedance, reducing the number of ports to realize the conversion of the six-port network into a four-port network, thereby improving the reliability of EMI filtering performance.

[0060] As an example of an embodiment of the present invention, the adaptive control module 16 is used to convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix based on the six-port network scattering parameters, obtain an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix, and obtain a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to control the impedance adjustment module to dynamically adjust the balanced impedance Rb, including: initializing the balanced impedance Rb to obtain an initial balanced impedance; obtaining an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix and a preset common-mode characteristic impedance; calculating the insertion loss based on the initial common-mode reflection coefficient; calculating the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude based on the initial common-mode reflection coefficient and the preset target reflection coefficient; updating the initial balanced impedance based on a preset gradient optimization algorithm until the insertion loss meets a preset convergence condition, and obtaining a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements, so as to control the impedance adjustment module to dynamically adjust the balanced impedance Rb.

[0061] In a specific implementation method, the adaptive control module 16 is internally configured with an optimization algorithm module for iteratively updating the value of Rb to maximize the common-mode insertion loss as much as possible. A method based on gradient descent or other adaptive algorithms can be used. Specifically, the balancing impedance Rb is initialized to an initial value R b0 , calculate the initial common mode reflection coefficient Γ based on the real-time measured SCC matrix and the preset common mode characteristic impedance S , and further calculate the insertion loss Av, according to the current initial common mode reflection coefficient Γ S and the target reflection coefficient Γ Target The difference between the target reflection coefficient Γ Target The calculation is as follows:

[0062]

[0063] Where Z EMIis the equivalent common mode impedance at the input of the EMI filter, obtained through real-time measurement, Z S is the equivalent common-mode noise source impedance of the impedance adjustment part. For detailed calculation, see Figure 3 , Figure 3 Schematic diagram of an equivalent circuit of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 1 ;like Figure 3 As shown, Z S is the equivalent common-mode noise source impedance of the impedance adjustment part; Z LCM is the equivalent impedance of the common-mode inductor of the EMI filter; Z C is the equivalent impedance of the EMI filter Y capacitor, and the equivalent common-mode noise source impedance Z of the impedance adjustment part S and EMI filter 11 Z C and Z LCM Together they form a T-type network, and the common-mode S parameters (S 11 、S 12 、S 21 and S 22 ) changes with the value of the balancing impedance Rb, Z S It can be obtained through the relationship between the T-type network and the port S parameters, as follows:

[0064]

[0065] Where Z 0CM is the common mode characteristic impedance, and the characteristic impedance Z of the common mode signal 0CM Equivalent impedance Z of EMI filter common mode inductor LCM The main purpose of impedance matching is to ensure that the common-mode signal can propagate without reflection on the transmission path, thereby minimizing noise. The equivalent impedance Z of the common-mode inductor of the EMI filter is LCM With Z 0CM The matching is achieved by adjusting the size of the common-mode inductor to ensure that the impedance of the two is equal or close.

[0066] Then calculate the initial balanced impedance adjustment direction and initial balanced impedance adjustment amplitude. The specific calculation formula is as follows:

[0067]

[0068] Where η is the learning rate, satisfying 0<η<1, Re represents the real part of the complex gradient; according to the obtained ΔR b Update the initial value R of the initial balancing impedance b0 , until the convergence condition ε is met:

[0069] ∣Γ S -Γ target∣<ε;

[0070] ε can be set according to actual needs. In addition to meeting the convergence conditions, it can also be set according to the obtained ΔR b Update the initial value R of the initial balancing impedance b0 Until the expected insertion loss level is reached, if the differential mode insertion loss needs to be optimized at the same time, the common mode reflection coefficient and the differential mode reflection coefficient can be included in the same objective function. By setting the weight coefficients α, β and the penalty factor γ in the objective function, the common mode and differential mode performance and the impedance adjustment range can be balanced, as shown in the following form:

[0071] min(α·|Γ S ∣+β·∣Γ L |+γ·|ΔR b ∣);

[0072] Where, Γ S is the initial common mode reflection coefficient, Γ L is the initial differential mode reflection coefficient; ΔR b Indicates the amplitude of the balanced impedance Rb adjustment; α and β are the weight coefficients of common-mode and differential-mode insertion loss respectively; γ is the impedance adjustment penalty factor, which is used to weigh the filtering performance and satisfy α, β, γ>0;

[0073] According to transmission line theory, Γ S The larger the value, the stronger the reflection. The insertion loss (or common-mode insertion voltage gain) Av can be calculated by Γ S and Γ L And the two-port (2-port and 4-port) S parameters of the EMI filter 11 obtained by measurement are described as follows:

[0074]

[0075] S 11 、S 12 、S 21 and S 22 These are parameters that describe the external characteristics of the EMI filter. Once the structure of the EMI filter 11 is selected, these parameters will not change. Therefore, if you want to further optimize the selected or designed EMI filter, the two reflection coefficients Γ S and Γ L The value of becomes the core issue of the design, see Figure 4 , Figure 4 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 3 ;like Figure 4As shown in FIG. 1 , in this embodiment, the load-side linear impedance stabilization network (LISN) is composed of capacitor CL1, capacitor CL2, inductor L1, inductor L2, resistor R1, resistor R2, and resistor RL. The load-side linear impedance stabilization network provides a stable common-mode impedance of 50Ω for the system, so Γ L unchanged, so Γ S becomes the only adjustable parameter to adjust the common mode insertion loss and optimize the EMI filter 11, because Γ S As the balancing impedance Rb changes, the impedance of the noise source can be adjusted by adjusting the balancing impedance Rb. Finally, when the resistance of the balancing impedance Rb meets the requirements, the optimal balancing impedance Rb adjustment direction and balancing impedance Rb adjustment amplitude ΔR are output. b , thereby controlling the impedance adjustment module to dynamically adjust the balancing impedance Rb.

[0076] Through the above scheme, the balanced impedance is initialized, and then the six-port network is converted into a four-port network and the separated mixed-mode common-mode parameter matrix is used to calculate the initial common-mode reflection coefficient and insertion loss. The initial common-mode reflection coefficient is then compared with the preset target reflection coefficient to obtain the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude. Through the preset gradient optimization algorithm, the initial balanced impedance is dynamically adjusted until the insertion loss meets the preset convergence condition, and the balanced impedance adjustment direction and the balanced impedance adjustment amplitude that meet the preset requirements are obtained, so as to adjust the balanced impedance Rb. When the circuit operating conditions change, the common-mode insertion loss is optimized according to the updated value of the mixed-mode common-mode parameter matrix, so as to realize real-time dynamic adjustment of the balanced impedance Rb and improve the reliability of EMI filtering performance.

[0077] As an example of an embodiment of the present invention, an initial common-mode reflection coefficient is obtained based on a mixed-mode common-mode parameter matrix and a preset common-mode characteristic impedance, including: obtaining a first equivalent impedance based on the mixed-mode common-mode parameter matrix and the preset common-mode characteristic impedance; obtaining the initial common-mode reflection coefficient based on a preset second equivalent impedance, the first equivalent impedance and the preset characteristic impedance.

[0078] For a specific implementation method, see Figure 3 , Figure 3 Schematic diagram of an equivalent circuit of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 1 ;like Figure 3 As shown, Z S is the equivalent common-mode noise source impedance of the impedance adjustment part (equivalent to the first equivalent impedance); Z LCM is the equivalent impedance of the common-mode inductor of the EMI filter; Z Cis the equivalent impedance of the EMI filter Y capacitor, and the equivalent common-mode noise source impedance Z of the impedance adjustment part S and EMI filter 11 Z C and Z LCM Together they form a T-type network, and the common-mode S parameters (S 11 、S 12 、S 21 and S 22 ) changes with the value of the balancing impedance Rb, Z S It can be obtained through the relationship between the T-type network and the port S parameters, as follows:

[0079]

[0080] Where Z 0CM is the common mode characteristic impedance, and the characteristic impedance Z of the common mode signal 0CM Equivalent impedance Z of EMI filter common mode inductor LCM The main purpose of impedance matching is to ensure that the common-mode signal can propagate without reflection on the transmission path, thereby minimizing noise. The equivalent impedance Z of the common-mode inductor of the EMI filter is LCM With Z 0CM The matching is achieved by adjusting the size of the common-mode inductor to ensure that the impedance of the two is equal or close.

[0081] From the above formula, we can see that the value of ZS depends on the four S parameters in the SCC matrix. Since different balancing impedance Rb values will produce different SCC matrices, the balancing impedance Rb can adjust the equivalent common mode impedance of the system impedance adjustment part, see Figure 5 , Figure 5 Schematic diagram of an equivalent circuit of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ,like Figure 5 As shown, V S is the equivalent common mode noise source; C Y is the Y capacitor of the common-mode filter; LCM is the common-mode inductor; Zn is the parasitic capacitance part of the common-mode noise source impedance (equivalent to the preset second equivalent impedance); ZS is the equivalent common-mode impedance of the six-port network, ZS = Z S +Z LCM +Z C , Zn and ZS constitute the noise source impedance of the entire system, thus, the initial common mode reflection coefficient Γ S It can be defined as:

[0082]

[0083] Through the above scheme, the preset common-mode characteristic impedance is matched by the existing characteristic matching principle, and then combined with the mixed-mode common-mode parameter matrix, the first equivalent impedance is calculated, and then the initial common-mode reflection coefficient is obtained based on the preset second equivalent impedance, the first equivalent impedance and the preset characteristic impedance. The impedance relationship of the entire EMI filtering device is reflected by calculating the reflection coefficient, which is subsequently reflected as the common-mode insertion loss, and then the performance of the entire EMI filtering device is reflected, providing a data basis for the subsequent dynamic adjustment of the balanced impedance, and improving the reliability of the EMI filtering performance.

[0084] As an example of an embodiment of the present invention, the balanced impedance adjustment module 14 is composed of a digitally controlled resistor array, and the balanced impedance adjustment module 14 is used to dynamically adjust the balanced impedance Rb, including: the digital communication interface of the digitally controlled resistor array is electrically connected to the adaptive control module 16, and the balanced impedance adjustment control signal sent by the adaptive control module 16 is received and executed through the digital communication interface of the digitally controlled resistor array.

[0085] A specific possible implementation method is that the balanced impedance adjustment module 14 is composed of a digitally controlled resistor array, which can be composed of a MOSFET switch matrix and a precision resistor network. The digitally controlled resistor array is electrically connected to the adaptive control module 16 through a digital communication interface, and receives and executes the balanced impedance adjustment control signal sent by the adaptive control module 16 through the digital communication interface of the digitally controlled resistor array. The digital communication interface is an SPI interface, and the bit accuracy of the balanced impedance adjustment control signal is ≥12 bits. The balanced impedance adjustment range covers 10Ω to 10kΩ, and the step resolution is not greater than 1Ω.

[0086] Through the above scheme, the balanced impedance adjustment module 14 is composed of a digitally controlled resistor array, and the digital communication interface is electrically connected to the adaptive control module 16. It can receive and execute the balanced impedance adjustment control signal sent by the adaptive control module 16, and realize continuous or discrete step-by-step adjustment within the resistance range, ensuring flexible adjustment of the balanced impedance Rb within a wide common-mode frequency band, thereby improving the reliability of EMI filtering performance.

[0087] Example 2

[0088] See also Figure 6 , Figure 6 A schematic flow chart of the steps of an EMI filtering method with adaptively adjustable noise source impedance provided by an embodiment of the present invention. Figure 6 As shown, the embodiment of the present invention provides an EMI filtering method with adaptive adjustable noise source impedance, including steps 101 to 104, each of which is specifically as follows:

[0089] Step 101: obtaining scattering parameters of a six-port network based on a preset impedance analysis algorithm;

[0090] Step 102 , based on the scattering parameters of the six-port network, convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix;

[0091] Step 103, obtaining an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix;

[0092] Step 104 : Based on the initial common-mode reflection coefficient and the preset target reflection coefficient, a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to dynamically adjust the balanced impedance Rb.

[0093] For a specific implementation method, see Figure 2 , Figure 2 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 2 ;like Figure 2 As shown, the coupled inductor 12 and the balanced winding 13 constitute the impedance adjustment part, and the circuit structure of the impedance adjustment part is as follows: Figure 2 As shown, the impedance adjustment part and the EMI filter 11 form a six-port network, and the scattering parameters (S parameters) are used to describe the six-port network, as shown in FIG. Figure 1 and Figure 2 As shown, port 1, port 2, port 3 and port 4 are the four ports of the coupled inductor 12 and the EMI filter 11, port 5 and port 6 are the two lead-out ports of the balanced winding 13, and the resistor Rb is connected in series between the 5th port and the 6th port as the balancing impedance Rb. The six-port network scattering parameters are obtained by the impedance analyzer (equivalent to the preset impedance analysis algorithm). The six-port network is described by the six-port network scattering parameters. Since the six-port network is not a standard differential structure, it is not easy to analyze it directly. Therefore, the balancing impedance Rb is connected in series between the 5th port and the 6th port, so that the remaining 1-4 ports form a new four-port network. The four-port network and the 5-port network form a new four-port network. It is related to the impedance in series between the 6 ports. According to the impedance mismatch principle, when the balanced impedance Rb is connected in series between the 5-port and 6-port, the power wave is reflected at these two ports. By calculating the impedance values of the 5-port and 6-port containing the balanced impedance Rb (equivalent to the impedance of the balanced winding lead-out port), the six-port network is converted into a four-port network. The four-port network is a standard differential structure. After obtaining the four-port network, the conversion between the differential and common modes is ignored, and the S parameters of the differential mode are converted into the mixed mode. The mixed mode common mode parameter matrix (SCC matrix) related to the balanced impedance Rb can be separated. The SCC matrix includes the S parameters (S 11 、S 12 、S 21 and S 22), by receiving the monitoring data of the six-port network from the noise spectrum real-time monitoring module 15 (feedback as the scattering parameters of the six-port network), the six-port network is converted into a four-port network according to the scattering parameters of the six-port network, and the mixed-mode common-mode parameter matrix SCC related to the balanced impedance Rb is extracted. In the high-frequency range, the SCC can be used to calculate key indicators such as the equivalent common-mode impedance and the common-mode insertion loss. The real-time six-port network equivalent impedance and the corresponding common-mode reflection coefficient (equivalent to the initial common-mode reflection coefficient) are calculated according to the mixed-mode common-mode parameter matrix SCC, and compared with the set target reflection coefficient or the preset common-mode impedance target (equivalent to the preset target reflection coefficient), and then a corresponding control signal (equivalent to the balanced impedance adjustment direction and balanced impedance adjustment amplitude that meet the preset requirements) is generated and sent to the balanced impedance adjustment module 14. The balanced impedance adjustment module 14 receives the corresponding control signal and adjusts the balanced winding 13 to achieve adaptive dynamic impedance adjustment.

[0094] As an example of an embodiment of the present invention, based on the initial common-mode reflection coefficient and the preset target reflection coefficient, a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance Rb, including: initializing the balanced impedance Rb to obtain an initial balanced impedance; calculating the insertion loss based on the initial common-mode reflection coefficient; calculating the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude based on the initial common-mode reflection coefficient and the preset target reflection coefficient; updating the initial balanced impedance based on a preset gradient optimization algorithm until the insertion loss meets a preset convergence condition, and obtaining the balanced impedance adjustment direction and the balanced impedance adjustment amplitude that meet preset requirements, to control the impedance adjustment module to dynamically adjust the balanced impedance Rb.

[0095] In a specific implementation method, after obtaining the mixed mode common mode parameter matrix (SCC matrix), the adaptive control module 16 is internally configured with an optimization algorithm module for iteratively updating the value of Rb to maximize the common mode insertion loss as much as possible. A method based on gradient descent or other adaptive algorithms can be used. Specifically, the balancing impedance Rb is initialized to an initial value R b0 , calculate the initial common mode reflection coefficient Γ based on the real-time measured SCC matrix and the preset common mode characteristic impedance S , and further calculate the insertion loss Av, according to the current initial common mode reflection coefficient Γ S and the target reflection coefficient Γ Target The difference between the target reflection coefficient Γ Target The calculation is as follows:

[0096]

[0097] Where Z EMIis the equivalent common mode impedance at the input of the EMI filter, obtained through real-time measurement, Z S is the equivalent common-mode noise source impedance of the impedance adjustment part. For detailed calculation, see Figure 3 , Figure 3 Schematic diagram of an equivalent circuit of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 1 ;like Figure 3 As shown, Z S is the equivalent common-mode noise source impedance of the impedance adjustment part; Z LCM is the equivalent impedance of the common-mode inductor of the EMI filter; Z C is the equivalent impedance of the EMI filter Y capacitor, and the equivalent common-mode noise source impedance Z of the impedance adjustment part S and EMI filter 11 Z C and Z LCM Together they form a T-type network, and the common-mode S parameters (S 11 、S 12 、S 21 and S 22 ) changes with the value of the balancing impedance Rb, Z S It can be obtained through the relationship between the T-type network and the port S parameters, as follows:

[0098]

[0099] Where Z 0CM is the common mode characteristic impedance, and the characteristic impedance Z of the common mode signal 0CM Equivalent impedance Z of EMI filter common mode inductor LCM The main purpose of impedance matching is to ensure that the common-mode signal can propagate without reflection on the transmission path, thereby minimizing noise. The equivalent impedance Z of the common-mode inductor of the EMI filter is LCM With Z 0CM The matching is achieved by adjusting the size of the common-mode inductor to ensure that the impedance of the two is equal or close.

[0100] Then calculate the initial balanced impedance adjustment direction and initial balanced impedance adjustment amplitude. The specific calculation formula is as follows:

[0101]

[0102] Where η is the learning rate, satisfying 0<η<1, Re represents the real part of the complex gradient; according to the obtained ΔR b Update the initial value R of the initial balancing impedance b0 , until the convergence condition ε is met:

[0103] ∣Γ S -Γ target∣<ε;

[0104] ε can be set according to actual needs. In addition to meeting the convergence conditions, it can also be set according to the obtained ΔR b Update the initial value R of the initial balancing impedance b0 Until the expected insertion loss level is reached, if the differential mode insertion loss needs to be optimized at the same time, the common mode reflection coefficient and the differential mode reflection coefficient can be included in the same objective function. By setting the weight coefficients α, β and the penalty factor γ in the objective function, the common mode and differential mode performance and the impedance adjustment range can be balanced, as shown in the following form:

[0105] min(α·|Γ S ∣+β·∣Γ L |+γ·|ΔR b ∣);

[0106] Where, Γ S is the initial common mode reflection coefficient, Γ L is the initial differential mode reflection coefficient; ΔR b Indicates the amplitude of the balanced impedance Rb adjustment; α and β are the weight coefficients of common-mode and differential-mode insertion loss respectively; γ is the impedance adjustment penalty factor, which is used to weigh the filtering performance and satisfy α, β, γ>0;

[0107] According to transmission line theory, Γ S The larger the value, the stronger the reflection. The insertion loss (or common-mode insertion voltage gain) Av can be calculated by Γ S and Γ L And the two-port (2-port and 4-port) S parameters of the EMI filter 11 obtained by measurement are described as follows:

[0108]

[0109] S 11 、S 12 、S 21 and S 22 These are parameters that describe the external characteristics of the EMI filter. Once the structure of the EMI filter 11 is selected, these parameters will not change. Therefore, if you want to further optimize the selected or designed EMI filter 11, the two reflection coefficients Γ S and Γ L The value of becomes the core issue of the design, see Figure 4 , Figure 4 A schematic diagram of the circuit structure of an EMI filter device with adaptive adjustable noise source impedance provided by an embodiment of the present invention Figure 3 ;like Figure 4As shown in FIG. 1 , in this embodiment, the load-side linear impedance stabilization network (LISN) is composed of capacitor CL1, capacitor CL2, inductor L1, inductor L2, resistor R1, resistor R2, and resistor RL. The load-side linear impedance stabilization network provides a stable common-mode impedance of 50Ω for the system, so Γ L unchanged, so Γ S becomes the only adjustable parameter to adjust the common mode insertion loss and optimize the EMI filter 11, because Γ S As the balancing impedance Rb changes, the impedance of the noise source can be adjusted by adjusting the balancing impedance Rb. Finally, when the resistance of the balancing impedance Rb meets the requirements, the optimal balancing impedance Rb adjustment direction and balancing impedance Rb adjustment amplitude ΔR are output. b , thereby controlling the impedance adjustment module to dynamically adjust the balancing impedance Rb.

[0110] An embodiment of the present invention proposes an EMI filtering method with adaptively adjustable noise source impedance. The method obtains a scattering coefficient of a six-port network by real-time monitoring of the common-mode noise spectrum of the EMI filter output port. Then, based on the scattering coefficient of the six-port network, the six-port network is converted into a four-port network with a differential structure. A mixed-mode common-mode parameter matrix is separated from the four-port network and an initial common-mode reflection coefficient is calculated. The balancing impedance Rb is dynamically adjusted by comparing with a preset target reflection coefficient. In this way, when the circuit operating condition changes, the change of the scattering coefficient of the six-port network is monitored, and the mixed-mode common-mode parameter matrix is quickly updated and compared with the preset target reflection coefficient to adjust the balancing impedance Rb, thereby improving the reliability of the EMI filtering performance.

[0111] Through the above scheme, the balanced impedance Rb is initialized, and then the six-port network is converted into a four-port network and the separated mixed-mode common-mode parameter matrix is used to calculate the initial common-mode reflection coefficient and insertion loss. The initial common-mode reflection coefficient is then compared with the preset target reflection coefficient to obtain the initial balanced impedance adjustment direction and the initial balanced impedance adjustment amplitude. Through the preset gradient optimization algorithm, the initial balanced impedance is dynamically adjusted until the insertion loss meets the preset convergence condition, and the balanced impedance adjustment direction and the balanced impedance adjustment amplitude that meet the preset requirements are obtained, so as to adjust the balanced impedance Rb. When the circuit operating conditions change, the differential-mode insertion loss is optimized according to the updated value of the mixed-mode common-mode parameter matrix, so as to realize real-time dynamic adjustment of the balanced impedance Rb and improve the reliability of EMI filtering performance.

[0112] As an example of an embodiment of the present invention, see Figure 7 、 Figure 8 and Figure 9 , Figure 7A schematic diagram of the original noise of an EMI filtering method with adaptively adjustable noise source impedance provided by an embodiment of the present invention; Figure 8 A comparison diagram of a conventional fixed-impedance EMI filter before and after noise optimization using an EMI filtering method with adaptively adjustable noise source impedance provided by one embodiment of the present invention; Figure 9 A comparison diagram of the noise before and after optimization of an EMI filtering device with an adaptively adjustable noise source impedance and an EMI filtering method with an adaptively adjustable noise source impedance provided by a certain embodiment of the present invention; Figure 7 、 Figure 8 and Figure 9 As shown, in order to verify the actual effect of the present invention, an EMI filter simulation system based on the MATLAB simulation platform is built. The electromagnetic interference suppression performance of a certain intelligent control device is tested and analyzed according to the adaptive control module 16 proposed in an embodiment of the present invention. The simulation test system mainly includes the following parts:

[0113] Electromagnetic interference source model: such as Figure 7 As shown in the figure, the simulation platform uses random noise superposition of different frequencies as the noise source, which generates significant common-mode electromagnetic interference signals during high-frequency switching, with a frequency range from 150kHz to 30MHz.

[0114] An embodiment of the present invention proposes a model of an EMI filtering device with adaptively adjustable noise source impedance: This device model is constructed entirely in accordance with the technical solutions in the embodiments of the present invention, including a six-port network, a balanced impedance adjustment module 14, and an adaptive control module 16. The balanced impedance Rb is measured and adjusted in real time through a simulation program to maximize the common-mode insertion loss.

[0115] Simulation process and parameter setting: During the simulation process, the balancing impedance Rb is initialized to the initial value R b0 =100Ω, the vector network analyzer simulation module is used to measure and extract the SCC matrix parameters in real time, and the adaptive control module 16 is used to determine the current initial common mode reflection coefficient Γ S and the target reflection coefficient Γ Target The difference between them is calculated and the balanced impedance value is gradually optimized through iterative adjustment.

[0116] The simulation compared the performance of a traditional fixed-impedance EMI filter and an EMI filtering device with adaptively adjustable noise source impedance proposed in an embodiment of the present invention. The experimental comparison scenario was a common-mode noise signal with a typical operating frequency range of 150kHz to 30MHz. The specific simulation test process was as follows: the initial impedance was set to a fixed value of 100Ω, and the common-mode insertion loss of the traditional fixed-impedance EMI filter was observed. In the simulation system, the EMI filtering device with adaptively adjustable noise source impedance was switched. The initial impedance was still set to 100Ω. The balancing impedance Rb was adjusted in real time using the EMI filtering method with adaptively adjustable noise source impedance proposed in an embodiment of the present invention, and the stable common-mode insertion loss performance after optimization was recorded.

[0117] The simulation test results are as follows: The effect of traditional fixed impedance EMI filter is as follows: Figure 8 As shown: In the high-frequency range of 30MHz to 100MHz, the noise intensity is approximately 20dB-70dB. The performance is limited by the fixed impedance value and cannot dynamically respond to changes in circuit operating conditions.

[0118] The effect of the filter device of the present invention with adaptive adjustable impedance EMI is as follows Figure 9 As shown in the figure: After the algorithm optimizes and adjusts the balanced impedance Rb in real time, the common-mode insertion loss of the filter in the same frequency band is significantly improved, which is significantly better than the fixed impedance filter solution. It effectively adapts to the dynamic changes in the circuit working conditions and can reduce all noise to below the limit (65dB), meeting the required requirements.

[0119] The above simulation results confirm that the EMI filtering device and method with adaptively adjustable noise source impedance proposed in the embodiments of the present invention can optimize and adjust the balancing impedance Rb in real time to cope with the dynamic changes in the circuit working conditions and improve the reliability of EMI filtering performance.

[0120] The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0121] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless otherwise expressly specified. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly specified.

Claims

1. An EMI filter device with adaptive adjustable noise source impedance, characterized in that: include: EMI filter, coupled inductor, balanced winding, balanced impedance, balanced impedance adjustment module, noise spectrum real-time monitoring module and adaptive control module; The EMI filter is electrically connected to the coupled inductor, and the coupled inductor, the EMI filter and the balanced winding form a six-port network; The balanced winding lead-out port is connected in series with the balanced impedance, the impedance adjustment module is electrically connected to the balanced winding lead-out port, the noise spectrum real-time monitoring module is electrically connected to the EMI filter output port, and the adaptive control module is electrically connected to the six-port network, the impedance adjustment module and the noise spectrum real-time monitoring module; The balanced impedance adjustment module is used to dynamically adjust the balanced impedance; The noise spectrum real-time monitoring module is used to detect the common-mode noise spectrum of the EMI filter output port, and determine whether the common-mode noise spectrum of the EMI filter output port meets the preset filter design requirements, and obtain the six-port network scattering parameters; The adaptive control module is used to convert the six-port network into a four-port network and construct a mixed-mode common-mode parameter matrix based on the six-port network scattering parameters, obtain an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix, and obtain a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to control the impedance adjustment module to dynamically adjust the balanced impedance.

2. The EMI filter device with adaptive adjustable noise source impedance according to claim 1, characterized in that: The EMI filter is electrically connected to the coupled inductor, and includes: The coupled inductor adopts two discrete inductors, and the two discrete inductors are respectively wound on two side columns of a preset magnetic core, and the central column of the preset magnetic core is provided with an air gap; An EMI filter electrical connection port is drawn out from the coupled inductor on two side columns of the preset magnetic core, so that the EMI filter is electrically connected to the coupled inductor.

3. The EMI filter device with adaptive adjustable noise source impedance according to claim 2, characterized in that: The balanced winding lead-out port is connected in series with the balanced impedance, comprising: The balance winding is wound on two side columns of the preset magnetic core and does not pass through the central column of the preset magnetic core, and the balance winding is in an "8" shape; Based on the balance winding on any side column of the preset magnetic core, the balance winding lead-out port is connected in series with the balance impedance.

4. The EMI filter device with adaptive adjustable noise source impedance according to claim 1, wherein: The adaptive control module is configured to convert the six-port network into a four-port network according to the scattering parameters of the six-port network and construct a mixed-mode common-mode parameter matrix; obtain an initial common-mode reflection coefficient according to the mixed-mode common-mode parameter matrix; and obtain a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to control the impedance adjustment module to dynamically adjust the balanced impedance, including: Based on the preset impedance analysis algorithm, the scattering parameters of the six-port network are obtained; Calculating the impedance of the balanced winding output port based on the six-port network scattering parameters; Based on the impedance of the balanced winding output port, the six-port network is converted into a four-port network, and the mixed-mode scattering parameters are obtained; Based on the mixed-mode scattering parameters, a mixed-mode common-mode parameter matrix is obtained.

5. The EMI filter device with adaptive adjustable noise source impedance according to claim 4, characterized in that: Calculating the balanced winding output port impedance based on the six-port network scattering parameters includes: Based on the scattering parameters and balanced impedance of the six-port network, a reflection coefficient of the balanced winding output port is obtained; Based on the reflection coefficient of the balanced winding lead-out port and the preset characteristic impedance, the balanced winding lead-out port impedance is obtained.

6. The EMI filter device with adaptively adjustable noise source impedance according to claim 5, characterized in that: The adaptive control module is configured to convert the six-port network into a four-port network according to the scattering parameters of the six-port network and construct a mixed-mode common-mode parameter matrix; obtain an initial common-mode reflection coefficient according to the mixed-mode common-mode parameter matrix; and obtain a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements based on the initial common-mode reflection coefficient and a preset target reflection coefficient, so as to control the impedance adjustment module to dynamically adjust the balanced impedance, including: Initializing the balancing impedance to obtain an initial balancing impedance; Obtaining an initial common-mode reflection coefficient based on the mixed-mode common-mode parameter matrix and a preset common-mode characteristic impedance; Calculating insertion loss based on the initial common-mode reflection coefficient; Calculating an initial balanced impedance adjustment direction and an initial balanced impedance adjustment amplitude based on the initial common-mode reflection coefficient and the preset target reflection coefficient; Based on a preset gradient optimization algorithm, the initial balanced impedance is updated until the insertion loss meets a preset convergence condition, and a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance.

7. The EMI filter device with adaptively adjustable noise source impedance according to claim 6, characterized in that: Based on the mixed-mode common-mode parameter matrix and the preset common-mode characteristic impedance, an initial common-mode reflection coefficient is obtained, including: Obtaining a first equivalent impedance based on the mixed-mode common-mode parameter matrix and a preset common-mode characteristic impedance; An initial common-mode reflection coefficient is obtained based on a preset second equivalent impedance, the first equivalent impedance, and the preset characteristic impedance.

8. The EMI filter device with adaptive adjustable noise source impedance according to claim 1, characterized in that: The balanced impedance adjustment module is composed of a digitally controlled resistor array, and is used to dynamically adjust the balanced impedance, including: The digital communication interface of the digitally controlled resistor array is electrically connected to the adaptive control module, and receives and executes the balanced impedance adjustment control signal sent by the adaptive control module through the digital communication interface of the digitally controlled resistor array.

9. An EMI filtering method with adaptive adjustable noise source impedance, characterized in that: An EMI filter device with adaptively adjustable noise source impedance as claimed in any one of claims 1 to 8, wherein the EMI filter device with adaptively adjustable noise source impedance comprises: a balancing impedance; The EMI filtering method with adaptive adjustable noise source impedance is executed by an adaptive control module and includes: Based on the preset impedance analysis algorithm, the scattering parameters of the six-port network are obtained; Based on the scattering parameters of the six-port network, the six-port network is converted into a four-port network and a mixed-mode common-mode parameter matrix is constructed; Based on the mixed mode common mode parameter matrix, obtaining an initial common mode reflection coefficient; Based on the initial common-mode reflection coefficient and the preset target reflection coefficient, a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to dynamically adjust the balanced impedance.

10. The EMI filtering method with adaptive adjustable noise source impedance according to claim 9, characterized in that: Based on the initial common-mode reflection coefficient and the preset target reflection coefficient, a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance, including: Initializing the balancing impedance to obtain an initial balancing impedance; Calculating insertion loss based on the initial common-mode reflection coefficient; Calculating an initial balanced impedance adjustment direction and an initial balanced impedance adjustment amplitude based on the initial common-mode reflection coefficient and the preset target reflection coefficient; Based on a preset gradient optimization algorithm, the initial balanced impedance is updated until the insertion loss meets a preset convergence condition, and a balanced impedance adjustment direction and a balanced impedance adjustment amplitude that meet preset requirements are obtained to control the impedance adjustment module to dynamically adjust the balanced impedance.

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