Common-mode noise resonance suppression method considering frequency-dependent characteristics of magnetic ring complex permeability

Abstract

The application belongs to the technical field of power electronic electromagnetic compatibility, and discloses a common-mode noise resonance suppression method considering the frequency variation characteristics of complex permeability of a magnetic ring, which is based on the frequency variation characteristics of complex permeability of the magnetic ring and a series resonance circuit model, defines a quality factor for evaluating resonance attenuation performance of the magnetic ring and a structure parameter reflecting geometric dimensions of the magnetic ring, establishes a mathematical relationship between the structure parameter and a resonance frequency and a design range expression by analyzing the frequency variation characteristics of complex impedance of the magnetic ring, and can design the magnetic ring with the most suitable material and the smallest size that meets performance requirements in limited installation space according to a given quality factor target, a magnetic ring size boundary constraint and a magnetic material permeability library. The application uses the above common-mode noise resonance suppression method considering the frequency variation characteristics of complex permeability of the magnetic ring, effectively reduces resonance peaks in a common-mode noise spectrum, significantly reduces the occupied space of the magnetic ring and EMI suppression cost, and thus improves the power density of the power electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic compatibility technology in power electronics, and in particular to a common-mode noise resonance suppression method that considers the frequency-varying characteristics of the complex permeability of a magnetic ring. Background Technology

[0002] With the widespread application of various power electronic conversion systems in data centers, electric vehicles, communication power supplies and industrial equipment, electromagnetic interference (EMI) caused by high-speed switching behavior in power semiconductor devices has become increasingly prominent. In particular, conducted common-mode (CM) noise has become one of the key factors restricting the performance and reliability of power electronic systems.

[0003] Impedance interactions exist between parasitic parameters in power electronic systems, causing resonant spikes in the common-mode noise spectrum. With the increasing number of components and the increasingly compact physical layout, parasitic parameters in converters, EMI filters, and cables couple at high frequencies, forming series resonant circuits. This resonance effect leads to sharp peaks in the common-mode noise in the MHz band. This not only makes it difficult for equipment to meet stringent EMC standards such as CISPR and MIL-STD, but also easily induces filter design failures, sensor failures, and even reduces the stability of the system control loop.

[0004] Blindly increasing filter margins can lead to a surge in size and cost, and a lack of design versatility. In engineering, increasing the design margin of EMI filters is a common approach, such as increasing the inductance of the filter inductor, increasing the capacitance of the filter capacitor, or raising the overall filter order, in order to mitigate the resonant amplification problem in the noise spectrum by increasing insertion loss. While this method may achieve the desired result, it significantly increases the filter's size, weight, cost, and additional losses. More importantly, this method does not address the resonance problem caused by the noise conduction path at its root. Its design results often depend on specific topologies, layouts, and device characteristics, lacking versatility. If system parameters change, the filter may need to be redesigned, severely extending the development cycle.

[0005] Existing methods for inserting magnetic rings neglect the frequency-varying characteristics of the complex permeability of magnetic materials, relying on trial and error, leading to inefficient designs. Inserting magnetic rings into resonant circuits is an effective means of suppressing high-frequency resonance. The equivalent resistance generated by such magnetic rings at high frequencies can play a role in resonance suppression within the resonant circuit. However, the complex permeability of magnetic materials has significant frequency-varying characteristics, which has a complex impact on the suppression effect: on the one hand, the imaginary permeability of the magnetic ring can only construct a high equivalent resistance within a limited frequency band; on the other hand, the equivalent inductance constructed by the real permeability of the magnetic ring participates in the resonance process, causing the resonant frequency to decrease. Once the resonant frequency is pulled down to outside the effective operating frequency band of the imaginary permeability, the magnetic ring will not be able to provide a sufficiently large equivalent resistance, resulting in a decrease in resonance suppression performance. Current engineering applications often ignore this mechanism, relying solely on experience to modify the number of magnetic rings and winding turns for "trial and error." This method cannot accurately balance the attenuation of resonant peaks and the resonant frequency shift, easily leading to over- or under-design, and is also time-consuming.

[0006] In summary, how to accurately select the material and size of a magnetic ring based on a full consideration of the frequency-varying characteristics of its complex permeability, in order to achieve efficient resonance suppression while minimizing the ring size, is a critical technical challenge that urgently needs to be addressed in the field of electromagnetic compatibility in power electronics. Summary of the Invention

[0007] The purpose of this invention is to provide a common-mode noise resonance suppression method that considers the frequency-varying characteristics of the complex permeability of a magnetic ring. The method aims to utilize the complex permeability of the magnetic ring to construct an equivalent resistance and consider the influence of the equivalent inductance, so as to effectively suppress the resonance of common-mode noise.

[0008] To achieve the above objectives, this invention provides a common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring, comprising the following steps: Step S1: Perform resonant circuit analysis on the circuit topology of the power electronic system to determine the dominant resonant parameters in the resonant circuit. L Loop and C Loop ; Step S2: Based on the magnetic ring design theory, through the magnetic core height H , inner diameter ID , outer diameter OD The impedance of a single-turn magnetic ring is characterized by its frequency and complex permeability. Z d ; Step S3: Start the evaluation from the complex permeability-frequency spectrum of the first material in the magnetic material library. Based on the real part of the complex permeability, derive the mathematical relationship between the structural parameters and the resonant frequency, and calculate the structural parameters corresponding to each resonant frequency. Step S4: Combining the input quality factor target, and based on the imaginary part of the complex permeability, derive the expression for the structural parameters-resonant frequency design range, and find the structural parameters that meet the damping requirements. Step S5: Find the minimum value among the structural parameters that meet the damping requirements and select it as the evaluation parameter for the corresponding material; repeat steps S3 and S4 for the remaining magnetic materials until all candidate materials have been evaluated; select the minimum value among all evaluation parameters as the target structural parameter. P so And select the most suitable magnetic material accordingly; Step S6: Under the design boundary requirements of the magnetic ring size in the actual scenario, based on the magnetic core design theory and the relationship between the magnetic ring size and the external volume, the magnetic ring size parameters that minimize the external volume and meet the target structural parameters are obtained through an iterative process. Then, the final magnetic ring is selected according to the data sheet of the corresponding magnetic material provided by the manufacturer.

[0009] Furthermore, in step S1, the dominant resonant parameters in the resonant circuit are determined, and the specific process is as follows: Since the source impedance of the power converter and the parasitic parameters of the common-mode filter introduce resonance, the common-mode current is calculated by simplifying the circuit. i cm As shown below: (1); (2); in, i cm This is the common-mode current; S It is a complex frequency; C S The equivalent capacitance of the source impedance; C C This is the rated capacitance of the filter capacitor branch; L C This is the parasitic inductance of the filter capacitor branch; R C This is the parasitic resistance of the filter capacitor branch; L S The equivalent inductance of the source impedance; L L This is the rated inductance of the filter inductor branch; Z LISN The load impedance; v s It is an equivalent noise voltage source; R S The parasitic resistance of the source impedance; According to the above formula, there exists a resonant frequency in the circuit. f re As shown below: (2); When the frequency equals the resonant frequency f re At that time, common-mode current i cm The first term in the denominator is zero; therefore, the resonant amplitude is determined by the parasitic resistance. R S and R C Decide; The dominant resonant parameters in the simplified circuit are shown below: (3); in, L Loop It is a resonant inductor; C Loop It is a resonant capacitor; R Loop This is the resonant resistor.

[0010] Furthermore, based on the dominant resonance parameter, characteristic impedance ρ and quality factor Q It is represented as: (4); According to the definition of a resonant circuit, through Q The amplitude of the quantized resonance peak.

[0011] Furthermore, in step S2, based on the magnetic ring design theory, the impedance of a single-turn magnetic ring is... Z d Through the height of the magnetic core H , inner diameter ID , outer diameter OD Characterized by frequency and complex permeability, as shown below: (5); in, i The imaginary unit; f For frequency; μ r ′ represents the real part of the complex permeability; μ r " represents the imaginary part of the complex permeability; μ 0 represents absolute permeability; H This refers to the core height. ID This refers to the inner diameter of the magnetic core. OD The outer diameter of the magnetic core; L d This is the equivalent inductance of the magnetic ring; R d This is the equivalent resistance of the magnetic ring; Imaginary part of complex permeability μr "Determines the equivalent resistance" R d The real part of complex permeability μ r The '' determines the equivalent inductance. L d Therefore, the magnetic ring can be represented as an RL series branch; given the desired quality factor of the resonant circuit Q g Below, ignore R Loop The impact, R d satisfy: (6); in, Q g This represents the desired quality factor.

[0012] Furthermore, in step S3, based on the real part of the complex permeability, the mathematical relationship between the structural parameters and the resonant frequency is derived, and the structural parameters corresponding to each resonant frequency are calculated. The specific process is as follows: The magnetic ring impedance of equation (5) Z d It can be broken down into a frequency-varying parameter and a frequency-independent structural parameter. P s Structural parameters P s It is the product of all parameters in the complex impedance equation of the magnetic ring that do not change with frequency. It is only related to the outer diameter, inner diameter, height and absolute permeability of the magnetic ring, and reflects the geometric dimensions and compactness of the magnetic ring, as shown below: (9); Based on the definition of a resonant circuit, the structural parameters are derived. P s The resonant frequency of the resonant circuit after adding a damping magnetic ring f red The mathematical relationship between them is as follows: (10); Equation (10) shows that, for a given magnetic material, at each frequency point f red The corresponding structural parameters can be calculated using the real part of the permeability. P s .

[0013] Furthermore, in step S4, based on the input quality factor target and the imaginary part of the complex permeability, the expression for the structural parameters-resonant frequency design range is derived, and the structural parameters that meet the damping requirements are found. The specific process is as follows: In the corresponding f red Place P s The expected quality factor of the design should be met. Q g The value is obtained by substituting the equivalent resistance contributed by the imaginary permeability into the quality factor conditions derived from equations (4) and (5), thus obtaining the quality factor of the resonant circuit after adding the damping magnetic ring. Q d Less than or equal to the expected quality factor Q g Time structure parameters P s The design scope is as follows: (11); Therefore, the design problem is transformed into a two-dimensional problem. P s – f red Design space; in space, equation (10) defines the resonant frequency f red Determined structural parameters P s Find the trajectory, and equation (11) gives the trajectory along which the trajectory is found. P s Damping constraints that must be satisfied.

[0014] Furthermore, in step S5, for each candidate magnetic material, firstly in P s – f red The curve described by equation (10) is plotted in the design space; due to the nonlinear variation of the magnetic permeability of the magnetic material, each P s Corresponding to multiple f red To comprehensively evaluate the damping performance of the magnetic core, all corresponding... f red The damping condition satisfying equation (11) is P s It was identified as a feasible design outcome; because P s Positively correlated with magnetic dimensions, therefore the smallest feasible value is selected. P s As an evaluation parameter for this material; After evaluating all candidate magnetic materials, the minimum evaluation parameter is selected as the final target structural parameter. P so The most suitable magnetic material was selected.

[0015] Furthermore, in step S6, after obtaining the most suitable magnetic material and target structural parameters, the design boundary of the magnetic ring size is determined in combination with the actual installation scenario of the converter. The positive and negative power cables of the converter need to pass through the magnetic ring together. Under the requirement of high current power transmission, the inner diameter of the magnetic ring... ID The limit is set to the minimum allowed value; under this constraint, OD and H The coupling relationship is determined by equation (9) and the target structural parameters. P so Common restrictions; In actual installation space, the volume occupied by the magnetic ring is... V o As shown below: (12); Find the minimum value through iteration. V o The solution, specifically the process, is as follows: by OD As the independent variable, from ID Starting with the preset iteration step size, the calculation satisfies P so of H and external volume V o ; Except for the first round, determine whether the result of this round is greater than the result of the previous round. Once it is found that the result of this round is greater than the result of the previous round, the result of this round is greater than the result of the previous round. V o If the result is greater than the previous result, exit the iteration and output the result calculated in the previous iteration. H and OD As the magnetic ring size parameter that satisfies the resonance suppression target and occupies the smallest volume; Finally, select the final magnetic ring based on the datasheet of the corresponding magnetic material provided by the manufacturer.

[0016] Therefore, the present invention employs the above-mentioned common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring, and the beneficial effects are as follows: (1) More accurate evaluation of resonance attenuation effect: Based on the frequency variation characteristics of complex permeability of magnetic materials, this invention establishes a mapping relationship between quality factor and material and size of magnetic ring in combination with resonant circuit model, so as to accurately quantify the resonance attenuation performance of resonant suppression magnetic ring; in addition, this invention also considers the nonlinear characteristics of complex permeability, and by comparing the resonance attenuation effect at each possible resonant frequency, a more accurate final evaluation result is formed.

[0017] (2) Lower loss: The resonant suppression magnetic ring only provides effective equivalent resistance in the high-frequency resonant section and exhibits extremely low impedance characteristics in low-frequency power transmission states such as power frequency and DC. Therefore, it will not become an energy-consuming device in the main power circuit of the converter. Compared with the traditional magnetic ring trial and error method, the resonant suppression magnetic ring designed in this invention can just meet the resonant suppression target, avoid over-design problems, and thus reduce the magnetic loss of the magnetic ring.

[0018] (3) Less space required: By establishing a mapping relationship between the size parameters of the magnetic ring and the resonance attenuation capability, and combining the geometric boundary conditions of the magnetic ring for iterative optimization, the present invention can solve the optimal size combination in a limited installation space, thereby minimizing the impact of the magnetic ring on the converter structure layout.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 It is a high-frequency circuit diagram that includes source impedance and common-mode filter; Figure 2 This is a diagram showing the common-mode resonance phenomenon generated between the power converter and the CL-type common-mode filter. Figure 3 The diagram shows the installation method of the damping magnetic ring and the corresponding equivalent resonant circuit diagram; where (a) is the installation method of the damping magnetic ring; and (b) is the corresponding equivalent resonant circuit diagram. Figure 4 The diagrams show a comparison of the complex permeability-frequency spectrum of different magnetic materials; where (a) is nanocrystal #1; (b) is manganese-zinc ferrite #1; (c) is manganese-zinc ferrite #2; and (d) is nickel-zinc ferrite #1. Figure 5 This is a graph showing the evaluation results of different magnetic materials; Figure 6 This is a verification diagram of the resonance spike suppression effect; Figure 7 This is a flowchart of a common-mode noise resonance suppression method that considers the frequency-varying characteristics of the complex permeability of a magnetic ring according to the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] like Figure 7 As shown, the present invention provides a common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring, comprising the following steps: Step S1: Perform resonant circuit analysis on the circuit topology of the power electronic system to determine the dominant resonant parameters in the resonant circuit. L Loop andC Loop ; Step S2: Based on the magnetic ring design theory, through the magnetic core height H , inner diameter ID , outer diameter OD The impedance of a single-turn magnetic ring is characterized by its frequency and complex permeability. Z d ; Step S3: Start the evaluation from the complex permeability-frequency spectrum of the first material in the magnetic material library. Based on the real part of the complex permeability, derive the mathematical relationship between the structural parameters and the resonant frequency, and calculate the structural parameters corresponding to each resonant frequency. Step S4: Combining the input quality factor target, and based on the imaginary part of the complex permeability, derive the expression for the structural parameters-resonant frequency design range, and find the structural parameters that meet the damping requirements. Step S5: Find the minimum value among the structural parameters that meet the damping requirements and select it as the evaluation parameter for the corresponding material; repeat steps S3 and S4 for the remaining magnetic materials until all candidate materials have been evaluated; select the minimum value among all evaluation parameters as the target structural parameter and select the corresponding magnetic material as the most suitable material. Step S6: Under the design boundary requirements of the magnetic ring size in the actual scenario, based on the magnetic core design theory and the relationship between the magnetic ring size and the external volume, the magnetic ring size parameters that minimize the external volume and meet the target structural parameters are obtained through an iterative process. Then, the final magnetic ring is selected according to the data sheet of the corresponding magnetic material provided by the manufacturer.

[0023] Example 1 The technical solution of this invention will be introduced by taking the common CM noise resonance phenomenon generated between the power converter and the CL type common mode filter as an example.

[0024] Step S1: Perform resonant circuit analysis on the circuit topology of the power electronic system to determine the dominant resonant parameters in the resonant circuit. L Loop and C Loop .

[0025] like Figure 1 As shown, the source impedance of the power converter and the parasitic parameters of the common-mode filter may introduce resonance. To simplify the device, assume... C C Much larger than other capacitors, L L Much larger than other inductors, Z LISN Much larger than other resistors, therefore the common-mode current i cm It can be simplified to: (1); in, i cm This is the common-mode current; S It is a complex frequency; C S The equivalent capacitance of the source impedance; C C This is the rated capacitance of the filter capacitor branch; L C This is the parasitic inductance of the filter capacitor branch; R C This is the parasitic resistance of the filter capacitor branch; L S The equivalent inductance of the source impedance; L L This is the rated inductance of the filter inductor branch; Z LISN This is the load impedance, and is generally set as the equivalent impedance. v s It is an equivalent noise voltage source; R S The parasitic resistance is the source impedance.

[0026] According to the above formula, there exists a resonant frequency in the circuit. f re As shown below: (2); When the frequency equals the resonant frequency f re At that time, common-mode current i cm The first term in the denominator is zero; therefore, the resonant amplitude is mainly determined by the parasitic resistance. R S and R C The decision is made because these are typically very small, resulting in noticeable resonance peaks in the common-mode noise spectrum. Furthermore, common-mode filters are usually designed based on standard procedures that only consider low-frequency insertion loss, significantly reducing their high-frequency attenuation capabilities and potentially failing to suppress these resonance spikes. Figure 2 As shown. Therefore, the noise will exceed the limit, requiring the filter to be redesigned.

[0027] Based on the above analysis, this resonance can be identified as a typical RLC series resonance. Therefore Figure 1 The resonant path shown by the blue dashed line in the middle is further simplified to: Figure 3 The circuit shown in (b) has simplified resonant dominant parameters as follows: (3); in, LLoop It is a resonant inductor; C Loop It is a resonant capacitor; R Loop This is the resonant resistor.

[0028] Based on the dominant resonance parameter, characteristic impedance ρ and quality factor Q It is represented as: (4); According to the definition of a resonant circuit, the quality factor Q The smaller the value, the lower the resonance peak. When Q When the value is ≤1, no significant resonance peak will appear in the loop current spectrum. Therefore, Q The value can quantify the amplitude of the resonance peak.

[0029] Step S2: Based on the magnetic ring design theory, through the magnetic core height H , inner diameter ID , outer diameter OD The impedance of a single-turn magnetic ring is characterized by its frequency and complex permeability. Z d .

[0030] The quality factor can be reduced by increasing circuit damping. Q The frequency-varying magnetic loss of the magnetic ring is a common resonance suppression method. According to the Steinmetz equation, the frequency-varying magnetic loss of the magnetic ring can effectively dissipate the radio frequency energy excited by CM noise and avoid significant low-frequency power loss caused by circuit damping.

[0031] Based on magnetic ring design theory, the impedance of a single-turn magnetic ring Z d Via core height H , inner diameter ID , outer diameter OD Characterized by frequency and complex permeability, as shown below: (5); in, i The imaginary unit; f For frequency; μ r ′ represents the real part of the complex permeability; μ r " represents the imaginary part of the complex permeability; μ 0 represents absolute permeability; H This refers to the core height. ID This refers to the inner diameter of the magnetic core. OD The outer diameter of the magnetic core; L d This is the equivalent inductance of the magnetic ring; R dThis is the equivalent resistance of the magnetic ring.

[0032] Imaginary part of complex permeability μ r "Determines the equivalent resistance" R d , and the real part μ r The '' determines the equivalent inductance. L d Therefore, the magnetic ring can be represented as an RL series branch. To effectively suppress resonance spikes without affecting the low-frequency noise suppression performance of the original CM filter, the magnetic ring is installed between the power converter and the filter, as shown below. Figure 3 As shown in (a) above, the equivalent resonant circuit is as follows: Figure 3 As shown in (b) of the diagram.

[0033] Given the desired quality factor of a resonant circuit Q g Below, ignore R Loop The impact, R d It should meet the following requirements: (6); in, Q g This represents the desired quality factor.

[0034] As the above analysis shows, the equivalent resistance and equivalent inductance work together in the resonant circuit, only increasing the resistance. R d It will reduce the quality factor of the resonant circuit. Q d As shown below: (7); in, Q d The quality factor of the resonant circuit after adding a damping magnetic ring.

[0035] Only increase L d It will cause the resonant frequency f red Lower, thereby increase Q d This also affects the suppression performance of the magnetic ring, as shown below: (8); in, f red This is the resonant frequency of the resonant circuit after adding a damping magnetic ring.

[0036] although R d andL d These factors independently affect the resonant peak amplitude and resonant frequency, but they cannot be designed separately. As shown in equation (5), once the magnetic material and core dimensions are determined, R d and L d This will be determined simultaneously, and the resonant damping performance of the magnetic ring will also be determined accordingly.

[0037] The complex permeability of a magnetic material determines the magnetic ring. R d and L d The differences between them. This invention studies four magnetic materials in the magnetic material library, and their complex permeability spectra are as follows. Figure 4 As shown, different materials exhibit different initial permeability and frequency-dependent characteristics.

[0038] Real part of complex permeability μ r ′ and imaginary part μ r "It exhibits a complex frequency-dependent nonlinear coupling trend. It provides the imaginary part of the equivalent resistance." μ r ", has a large value only within a specific frequency band. If in the real part μ r ′Constructed L d Under the influence of, resonant frequency f red Exceeded μ r The effective frequency band of the magnetic ring, and the equivalent resistance it can provide. R d The impedance will decrease, and its resonance suppression performance will also be affected. Therefore, the relationship between impedance and inductance depends on both material properties and frequency.

[0039] Once the material is determined, the size of the magnetic ring further quantifies its impact on the resonant circuit. According to equation (5), the size of the magnetic ring can be simultaneously scaled. R d and L d The numerical value is given. Therefore, an optimal design can be achieved by adjusting the size of the magnetic ring to balance the attenuation of the resonant peak and the shift in the resonant frequency. Thus, the key to damping design lies in the selection of the magnetic material and precise dimensional design.

[0040] Step S3: Start the evaluation from the complex permeability-frequency spectrum of the first material in the magnetic material library. Based on the real part of the complex permeability, derive the mathematical relationship between the structural parameters and the resonant frequency, and calculate the structural parameters corresponding to each resonant frequency.

[0041] Considering the limited installation space in high-power converters, the added magnetic ring cannot be increased indefinitely. Therefore, it is necessary to quantitatively analyze the relationship between the magnetic ring's resonant attenuation capability and its size. The magnetic ring impedance in equation (5) is... Z d It can be broken down into a frequency-varying parameter and a frequency-independent structural parameter. P s Structural parameters P s It is the product of all parameters in the complex impedance equation of the magnetic ring that do not change with frequency. It is only related to the outer diameter, inner diameter, height and absolute permeability of the magnetic ring, and reflects the geometric dimensions and compactness of the magnetic ring, as shown below: (9); Based on the definition of a resonant circuit, the following is derived: P s and f red The mathematical relationship between them is as follows: (10); Equation (10) shows that, for a given magnetic material, P s Each value corresponds to a value determined by the real part of the permeability. f red Furthermore, in the corresponding f red Place P s It should meet the expected quality factor of the design. Q g value.

[0042] Step S4: Combining the input quality factor target, and based on the imaginary part of the complex permeability, derive the expression for the structural parameters-resonant frequency design range, and find the structural parameters that meet the damping requirements.

[0043] Substituting the equivalent resistance contributed by the imaginary permeability into the quality factor condition derived from equations (4) and (5), we obtain the condition that satisfies... Q d ≤ Q g Time structure parameters P s The design scope is as follows: (11); Therefore, the design problem is transformed into a two-dimensional problem. P s – f redDesign space. In this space, equation (10) defines the resonant frequency. f red Determined structural parameters P s Find the trajectory, and equation (11) gives the path along this trajectory. P s Damping constraints that must be satisfied.

[0044] Step S5: Find the minimum value among the structural parameters that meet the damping requirements and select it as the evaluation parameter for the corresponding material; repeat steps S3 and S4 for the remaining magnetic materials until all candidate materials have been evaluated; select the minimum value among all evaluation parameters as the target structural parameter and select the corresponding magnetic material as the most suitable material.

[0045] For each candidate magnetic material, firstly in P s – f red The curve described by equation (10) is plotted in the design space. Due to the nonlinear variation of the magnetic permeability of the magnetic material, each P s It may correspond to multiple f red To comprehensively evaluate the damping performance of the magnetic core, tests will be conducted on all corresponding cores. f red The damping condition satisfying equation (11) is P s It was identified as a feasible design outcome.

[0046] because P s Positively correlated with magnetic dimensions, therefore the smallest feasible value is selected. P s This serves as an evaluation parameter for the material. This choice ensures sufficient resonant damping while avoiding unnecessary increases in core volume and weight.

[0047] After evaluating all candidate magnetic materials, the minimum evaluation parameter is selected as the final target structural parameter. P so The most suitable magnetic material was selected.

[0048] Step S6: Under the design boundary requirements of the magnetic ring size in the actual scenario, based on the magnetic core design theory and the relationship between the magnetic ring size and the external volume, the magnetic ring size parameters that minimize the external volume and meet the target structural parameters are obtained through an iterative process. Then, the final magnetic ring is selected according to the data sheet of the corresponding magnetic material provided by the manufacturer.

[0049] After obtaining the most suitable magnetic material and target structural parameters, the design boundaries of the magnetic ring size need to be determined based on the actual installation scenario of the converter. As the preceding analysis shows, the positive and negative power cables of the converter need to pass through the magnetic ring together, such as... Figure 3 As shown in (a) above. Under the requirement of high current power transmission, the inner diameter of the magnetic ring... ID The limit is set to the minimum allowed value; under this constraint, OD and H The coupling relationship is (9) and the target structure parameters. P so Common restrictions.

[0050] In actual installation space, the volume occupied by the magnetic ring of equation (12) is [not specified]. V o More attention received V o The calculation method is as follows: (12); Therefore, the minimum is found iteratively. V o The solution, specifically the process, is as follows: by OD As the independent variable, from ID Starting with the preset iteration step size, the calculation satisfies P so of H and external volume V o ; Except for the first round, determine whether the result of this round is greater than the result of the previous round. Once it is found that the result of this round is greater than the result of the previous round, the result of this round is greater than the result of the previous round. V o If the result is greater than the previous result, exit the iteration and output the result calculated in the previous iteration. H and OD The magnetic ring size parameter is used to satisfy the resonance suppression target while minimizing the volume occupied.

[0051] Finally, select the final magnetic ring based on the datasheet of the corresponding magnetic material provided by the manufacturer.

[0052] Example 2 To verify the proposed method, a 40kW isolated DC-DC converter was constructed for EMI testing. When a CL common-mode filter was inserted at the input of the converter, a significant common-mode resonance peak was observed on the LISN, such as... Figure 2 As shown. By measuring the input common-mode source impedance and the equivalent common-mode impedance of the filter capacitor branch, the resonant parameters were determined to be... C Loop =6.7nF and L Loop =234nH.

[0053] In light of the aforementioned resonance problem, the method proposed in this invention is used for magnetic ring design. The design objective is to eliminate significant resonance spikes in the noise spectrum, with a desired quality factor. Q g Set to 1.

[0054] Four types of magnetic materials P s – f red The evaluation results in the design space are as follows: Figure 5 As shown in the figure. The evaluation parameter points for each parameter are also marked in the figure. The comparison shows that the nanocrystalline #1 material performs best. To ensure the magnetic core can accommodate two cables, ID It must be at least 22mm. Taking into account... V o Minimizing values ​​and manufacturing constraints, the selection of the final magnetic core is based on the datasheet of the corresponding magnetic material. P s The value is 1.43e-10. This magnetic ring is... f red It provides a resistor of approximately 8.5Ω and an inductor of 209nH. For example... Figure 6 As shown in the figure, the CM noise spectrum before and after the addition of the magnetic ring is further displayed. As can be seen from the figure, the magnetic ring suppresses the resonant peak by about 27dB at the resonant frequency, so that the final converter meets the corresponding standard requirements and the resonant peak is almost unobservable.

[0055] Therefore, this invention employs a common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring. Based on the frequency-varying characteristics of the complex permeability of magnetic materials, and combined with a resonant circuit model, a mapping relationship between the quality factor and the material and size of the magnetic ring is established to accurately quantify the resonance attenuation performance of the resonance suppression magnetic ring. Furthermore, this invention also considers the nonlinear characteristics of the complex permeability, and by comparing the resonance attenuation effect at each possible resonant frequency, a more accurate final evaluation result is formed. The resonance suppression magnetic ring designed in this invention precisely meets the resonance suppression target, avoiding over-design problems and thus reducing the magnetic loss of the magnetic ring. By establishing a mapping relationship between the size parameters of the magnetic ring and the resonance attenuation capability, and combining iterative optimization with the geometric boundary conditions of the magnetic ring, the optimal size combination can be solved within a limited installation space, thereby minimizing the impact of the magnetic ring on the converter structural layout.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring, characterized in that, Includes the following steps: Step S1: Perform resonant circuit analysis on the circuit topology of the power electronic system to determine the dominant resonant parameters in the resonant circuit. L Loop and C Loop ; Step S2: Based on the magnetic ring design theory, through the magnetic core height H , inner diameter ID , outer diameter OD The impedance of a single-turn magnetic ring is characterized by its frequency and complex permeability. Z d ; Step S3: Start the evaluation from the complex permeability-frequency spectrum of the first material in the magnetic material library. Based on the real part of the complex permeability, derive the mathematical relationship between the structural parameters and the resonant frequency, and calculate the structural parameters corresponding to each resonant frequency. Step S4: Combining the input quality factor target, and based on the imaginary part of the complex permeability, derive the expression for the structural parameters-resonant frequency design range, and find the structural parameters that meet the damping requirements. Step S5: Find the minimum value among the structural parameters that meet the damping requirements and select it as the evaluation parameter for the corresponding material; repeat steps S3 and S4 for the remaining magnetic materials until all candidate materials have been evaluated; select the minimum value among all evaluation parameters as the target structural parameter. P so And select the most suitable magnetic material accordingly; Step S6: Under the design boundary requirements of the magnetic ring size in the actual scenario, based on the magnetic core design theory and the relationship between the magnetic ring size and the external volume, the magnetic ring size parameters that minimize the external volume and meet the target structural parameters are obtained through an iterative process. Then, the final magnetic ring is selected according to the data sheet of the corresponding magnetic material provided by the manufacturer.

2. The common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 1, characterized in that, In step S1, the dominant resonant parameters in the resonant circuit are determined, and the specific process is as follows: Since the source impedance of the power converter and the parasitic parameters of the common-mode filter introduce resonance, the common-mode current is calculated by simplifying the circuit. i cm As shown below: （1）； （2）； in, i cm This is the common-mode current; S It is a complex frequency; C S The equivalent capacitance of the source impedance; C C This is the rated capacitance of the filter capacitor branch; L C This is the parasitic inductance of the filter capacitor branch; R C This is the parasitic resistance of the filter capacitor branch; L S The equivalent inductance of the source impedance; L L This is the rated inductance of the filter inductor branch; Z LISN The load impedance; v s It is an equivalent noise voltage source; R S The parasitic resistance of the source impedance; According to the above formula, there exists a resonant frequency in the circuit. f re As shown below: （2）； When the frequency equals the resonant frequency f re At that time, common-mode current i cm The first term in the denominator is zero; therefore, the resonant amplitude is determined by the parasitic resistance. R S and R C Decide; The dominant resonant parameters in the simplified circuit are shown below: （3）； in, L Loop It is a resonant inductor; C Loop It is a resonant capacitor; R Loop This is the resonant resistor.

3. The common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 2, characterized in that, Based on the dominant resonance parameter, characteristic impedance ρ and quality factor Q It is represented as: （4）； According to the definition of a resonant circuit, through Q The amplitude of the quantized resonance peak.

4. The common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 3, characterized in that, In step S2, based on the magnetic ring design theory, the impedance of a single-turn magnetic ring is... Z d Through the height of the magnetic core H , inner diameter ID , outer diameter OD Characterized by frequency and complex permeability, as shown below: （5）； in, i The imaginary unit; f For frequency; μ r ′ represents the real part of the complex permeability; μ r " represents the imaginary part of the complex permeability; μ 0 represents absolute permeability; H This refers to the core height. ID This refers to the inner diameter of the magnetic core. OD The outer diameter of the magnetic core; L d This is the equivalent inductance of the magnetic ring; R d This is the equivalent resistance of the magnetic ring; Imaginary part of complex permeability μ r "Determines the equivalent resistance" R d The real part of complex permeability μ r The '' determines the equivalent inductance. L d Therefore, the magnetic ring can be represented as an RL series branch; given the desired quality factor of the resonant circuit Q g Below, ignore R Loop The impact, R d satisfy: （6）； in, Q g This represents the desired quality factor.

5. A common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 4, characterized in that, In step S3, based on the real part of the complex permeability, the mathematical relationship between the structural parameters and the resonant frequency is derived, and the structural parameters corresponding to each resonant frequency are calculated. The specific process is as follows: The magnetic ring impedance of equation (5) Z d It can be broken down into a frequency-varying parameter and a frequency-independent structural parameter. P s Structural parameters P s It is the product of all parameters in the complex impedance equation of the magnetic ring that do not change with frequency. It is only related to the outer diameter, inner diameter, height and absolute permeability of the magnetic ring, and reflects the geometric dimensions and compactness of the magnetic ring, as shown below: （9）； Based on the definition of a resonant circuit, the structural parameters are derived. P s The resonant frequency of the resonant circuit after adding a damping magnetic ring f red The mathematical relationship between them is as follows: （10）； Equation (10) shows that, for a given magnetic material, at each frequency point f red The corresponding structural parameters can be calculated using the real part of the permeability. P s .

6. A common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 5, characterized in that, In step S4, based on the input quality factor target and the imaginary part of the complex permeability, the expression for the structural parameters-resonant frequency design range is derived, and the structural parameters that meet the damping requirements are found. The specific process is as follows: In the corresponding f red Place P s The expected quality factor of the design should be met. Q g The value is obtained by substituting the equivalent resistance contributed by the imaginary permeability into the quality factor conditions derived from equations (4) and (5), thus obtaining the quality factor of the resonant circuit after adding the damping magnetic ring. Q d Less than or equal to the expected quality factor Q g Time structure parameters P s The design scope is as follows: （11）； Therefore, the design problem is transformed into a two-dimensional problem. P s – f red Design space; in space, equation (10) defines the resonant frequency f red Determined structural parameters P s Find the trajectory, and equation (11) gives the trajectory along which the trajectory is found. P s Damping constraints that must be satisfied.

7. A common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 6, characterized in that, In step S5, for each candidate magnetic material, firstly in P s – f red The curve described by equation (10) is plotted in the design space; due to the nonlinear variation of the magnetic permeability of the magnetic material, each P s Corresponding to multiple f red To comprehensively evaluate the damping performance of the magnetic core, all corresponding... f red The damping condition satisfying equation (11) is P s It was identified as a feasible design outcome; because P s Positively correlated with magnetic dimensions, therefore the smallest feasible value is selected. P s As an evaluation parameter for this material; After evaluating all candidate magnetic materials, the minimum evaluation parameter is selected as the final target structural parameter. P so The most suitable magnetic material was selected.

8. A common-mode noise resonance suppression method considering the frequency-varying characteristics of the complex permeability of a magnetic ring according to claim 7, characterized in that, In step S6, after obtaining the most suitable magnetic material and target structural parameters, the design boundary of the magnetic ring size is determined in combination with the actual installation scenario of the converter. The positive and negative power cables of the converter need to pass through the magnetic ring together. Under the requirement of high current power transmission, the inner diameter of the magnetic ring... ID The limit is set to the minimum allowed value; under this constraint, OD and H The coupling relationship is determined by equation (9) and the target structural parameters. P so Common restrictions; In actual installation space, the volume occupied by the magnetic ring is... V o As shown below: （12）； Find the minimum value through iteration. V o The solution, specifically the process, is as follows: by OD As the independent variable, from ID Starting with the preset iteration step size, the calculation satisfies P so of H and external volume V o ; Except for the first round, determine whether the result of this round is greater than the result of the previous round. Once it is found that the result of this round is greater than the result of the previous round, the result of this round is greater than the result of the previous round. V o If the result is greater than the previous result, exit the iteration and output the result calculated in the previous iteration. H and OD As the magnetic ring size parameter that satisfies the resonance suppression target and occupies the smallest volume; Finally, select the final magnetic ring based on the datasheet of the corresponding magnetic material provided by the manufacturer.

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