Electromagnetic self-shielded inverter transformer
By introducing leakage flux measurement, magnetic circuit guidance, and feedback adjustment modules into the inverter transformer, the problems of uncertain leakage flux dispersion and mismatch in low magnetic reluctance channel layout are solved, realizing directional migration and efficient capture of leakage flux, and improving the bias suppression effect and capture efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- COSCO SHIPPING (QIDONG) OFFSHORE CO LTD
- Filing Date
- 2026-06-10
- Publication Date
- 2026-07-31
AI Technical Summary
In the existing inverter transformer's magnetic circuit self-shielding design, the leakage flux dispersion direction is uncertain and lacks directional guidance. The layout of the low magnetic resistance channel does not match the leakage flux dispersion situation, and there is a lack of quantitative assessment and feedback adjustment methods. As a result, the leakage flux escapes into the windings and structural components, resulting in large eddy current losses and insufficient release of bias magnetic suppression effectiveness.
The leakage flux measurement module is used to determine the main radiation direction and dispersion angle range of the diffuse leakage flux. The magnetic circuit guidance module plans the directional magnetic potential gradient path to guide the leakage flux to the low magnetic reluctance channel. Combined with the efficiency calculation module and the feedback adjustment module, the magnetic circuit parameters are adjusted in real time to improve the leakage flux capture efficiency and form a self-shielding closed loop.
It achieves directional migration and efficient capture of leakage flux, reduces leakage flux dissipation to windings and structural components, improves bias suppression effect, and optimizes magnetic circuit structure through quantitative indicators, thereby improving the controllability and stability of capture efficiency.
Smart Images
Figure CN122494432A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of transformer technology and relates to an electromagnetic self-shielded inverter transformer. Background Technology
[0002] When an inverter transformer operates under rectifier-inverter conditions, the superposition effect of common-mode interference voltage introduces a DC bias component into the magnetic circuit, causing the core operating point to shift towards the saturation region, resulting in excitation current distortion and increased harmonics. To prevent the core from entering the saturation region, an unsaturated air gap is typically set in the main magnetic circuit to maintain the linear operating range of the core. At the same time, a low magnetic reluctance channel is configured to absorb the leakage flux generated at the air gap, achieving passive bias suppression.
[0003] In the prior art, a typical approach to magnetic circuit self-shielding is to arrange a low magnetic reluctance bypass structure made of high magnetic permeability material around the unsaturated air gap. The inlet section of the low magnetic reluctance channel passively intercepts the leakage magnetic flux diffusing outward from the air gap and guides it back into the low magnetic reluctance channel, thereby reducing the leakage magnetic flux from dissipating into the windings and structural components.
[0004] The aforementioned existing technical solutions have the following drawbacks: First, the direction of leakage flux dispersion is uncertain, lacking a directional guidance mechanism. Due to a sudden change in magnetic reluctance, the flux at the unsaturated air gap disperses outwards, exhibiting a non-directional, wide-area distribution in the space surrounding the air gap. The low-resistance channel relies solely on passive interception at the inlet section, lacking a means to actively gather and directionally migrate the widely dispersed leakage flux to the inlet of the low-resistance channel. This results in a large amount of leakage flux still escaping into the windings and structural components, generating eddy current losses. The absorption capacity of the low-resistance channel is far lower than its structural capacity, and the bias suppression effectiveness is not fully released.
[0005] Second, the layout of the low magnetoresistance channel does not match the actual dispersion pattern of the leakage flux. Existing technologies typically rely on empirical design or rough simulation to determine the placement and guidance direction of the low magnetoresistance channel, without conducting field measurements and guidance path planning based on the actual spatial distribution characteristics of the dispersed leakage flux under specific operating conditions. This results in a spatial misalignment between the low magnetoresistance channel and the leakage flux dispersion area, leading to low interception efficiency.
[0006] Third, the capture effect lacks quantitative evaluation and feedback adjustment methods. Existing solutions do not establish quantitative evaluation indicators for leakage flux capture performance, nor do they provide a mechanism for adjusting magnetic circuit configuration parameters based on actual capture results. This makes it impossible to continuously optimize the magnetic circuit shielding structure during operation or design phases, and the improvement of bias suppression effect is limited to one-time empirical design. Summary of the Invention
[0007] In view of this, in order to solve the problems mentioned in the background technology, an electromagnetic self-shielding inverter transformer is proposed.
[0008] The objective of this invention can be achieved through the following technical solution: This invention provides an electromagnetic self-shielded inverter transformer, comprising: a leakage flux measurement module, a magnetic circuit guidance module, an efficiency calculation module, and a feedback adjustment module.
[0009] The leakage flux measurement module is connected to the magnetic circuit guidance module, the magnetic circuit guidance module is connected to the efficiency calculation module, and the efficiency calculation module is bidirectionally connected to the feedback adjustment module.
[0010] The leakage flux measurement module determines the main radiation direction and dispersion angle range of the diffuse leakage flux based on the amplitude and vector direction of the leakage flux density at the calibration point outside the unsaturated air gap region.
[0011] The magnetic circuit guidance module plans a guidance path from the air gap dispersion source center to the low magnetic resistance channel inlet interception surface based on the main radiation direction and dispersion spread angle range. It divides multiple transition sections with monotonically decreasing magnetic resistance values along the guidance path to form a directional magnetic potential gradient, which drives the dispersion leakage flux to contract directionally along the guidance path and merge into the low magnetic resistance channel.
[0012] The efficiency calculation module calculates the ratio of the flux reinjection at the low magnetic reluctance channel outlet to the total amount of diffuse leakage flux in the unsaturated air gap region, which is used as the leakage flux capture efficiency.
[0013] The feedback adjustment module, when the leakage flux capture efficiency is less than the preset efficiency threshold, selects the arrangement density or magnetic reluctance reduction gradient of the transition section as the adjustment object according to the degree of efficiency deviation and the spatial constraints of the transition section, implements corresponding adjustment measures, and re-executes the efficiency calculation module until the capture efficiency meets the target or reaches the maximum number of iterations.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention determines the main radiation direction and dispersion angle range based on the measured leakage flux density amplitude and vector direction, and configures a transition section with monotonically decreasing magnetic reluctance value along the guide path to form a directional magnetic potential gradient pointing to the entrance of the low magnetic reluctance channel. A clear magnetic potential difference is established between the air gap dispersion source core and the entrance of the low magnetic reluctance channel, so that the originally non-directional wide-area dispersion leakage flux obtains a continuous migration driving force along the guide path direction, and the dispersion range is concentrated into the spatial area defined by the guide path, directly reducing the leakage flux that escapes to the winding and structural components.
[0015] (2) This invention uses the measured diffuse leakage flux parameters to determine the main radiation direction and span range as the basis for planning the guiding path, locates the entrance position of the low magnetic reluctance channel, and determines the path cross-sectional width according to the diffuse span range. This makes the direction and cross-sectional coverage area of the guiding path match the actual diffuse state of the leakage flux in space, and the entrance interception surface is placed at the interface position of the permeability change on the natural transmission path of the leakage flux, reducing the interception omissions caused by the misalignment between the path and the diffuse area.
[0016] (3) This invention uses the ratio of magnetic flux reinjection to total diffuse leakage flux as the leakage flux capture efficiency, providing a quantitative basis for judging the magnetic circuit shielding effect. When the capture efficiency does not reach the preset efficiency threshold, the arrangement density or magnetic reluctance reduction gradient is adjusted according to the degree of efficiency deviation and spatial constraints. After adjustment, the capture efficiency is recalculated to form an iterative closed loop. The bias magnetic suppression effect is transformed from relying on one-time empirical design to a continuous adjustment process based on quantitative indicators, so that the capture efficiency can converge to the design target. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the module connection of the present invention.
[0019] Figure 2 This is a schematic diagram illustrating the logic for determining the principal radiation direction and dispersion angle range of the diffuse leakage flux in the leakage flux measurement module of this invention.
[0020] Figure 3 This is a schematic diagram illustrating the implementation steps of the adjustment measures in the feedback adjustment module of the present invention when the arrangement density of the transition section is selected as the adjustment object. Detailed Implementation
[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Please see Figure 1 As shown, the present invention provides an electromagnetic self-shielded inverter transformer, comprising: a leakage flux measurement module, a magnetic circuit guidance module, an efficiency calculation module, and a feedback adjustment module.
[0023] The leakage flux measurement module is connected to the magnetic circuit guidance module, the magnetic circuit guidance module is connected to the efficiency calculation module, and the efficiency calculation module is bidirectionally connected to the feedback adjustment module.
[0024] The hardware and structural environment upon which this invention is based is as follows: The electromagnetic self-shielded inverter transformer includes a main magnetic circuit of the iron core, a primary winding, a secondary winding, and an unsaturated air gap region located between the primary and secondary windings. The unsaturated air gap region is filled with non-ferromagnetic material to prevent the iron core from entering a magnetic saturation state under DC bias or asymmetrical load conditions. Because the magnetic reluctance of the unsaturated air gap region is much higher than that of the adjacent iron core material, when the magnetic flux of the main magnetic circuit passes through the air gap, some magnetic lines of force diffuse outward from the edge of the air gap, forming diffuse leakage flux. This invention actively collects and reinjects the diffuse leakage flux back to the main magnetic circuit by constructing a guiding path and a low magnetic reluctance recovery channel around the air gap, forming a self-shielded closed loop.
[0025] Using the geometric center of the unsaturated air gap region as a reference, multiple peripheral calibration measurement points are arranged on a virtual sphere surrounding the air gap region. The radius of the virtual sphere is the radial distance corresponding to when the leakage magnetic flux density decays to half of the peak value at the air gap edge. The measurement points are arranged at equal solid angle intervals along the meridian and parallel directions of the sphere, with a total number of no less than 8 points. The magnetic flux density sensing unit at each measurement point simultaneously collects magnetic flux density components in three orthogonal directions. A magnetic flux density sensing unit is fixedly installed at each peripheral calibration measurement point, and its factory calibration report provides the percentage of repeatability measurement error.
[0026] Within the space between the inner wall of the transformer casing and the main magnetic circuit of the core, a low magnetic reluctance channel is reserved, extending from the outer periphery of the air gap to the injection node of the main magnetic circuit of the core. The low magnetic reluctance channel is constructed of a high-permeability material, with its inlet end facing the main direction of the diffuse leakage flux and its outlet end connected to the low flux density node of the main magnetic circuit of the core.
[0027] The main magnetic circuit of the iron core, the primary winding, the secondary winding, the unsaturated air gap region, the peripheral calibration measuring points, the magnetic flux density sensing unit, the guiding path, the transition section, and the low magnetic reluctance channel together constitute a complete electromagnetic self-shielding structure.
[0028] The leakage flux measurement module determines the main radiation direction and dispersion angle range of the diffuse leakage flux based on the amplitude and vector direction of the leakage flux density at the calibration point outside the unsaturated air gap region.
[0029] Specifically, when the inverter transformer is operating at its rated input voltage and rated load, synchronous sampling is performed on the magnetic flux density sensing units at each peripheral calibration measurement point. The sampling frequency can be set to 10 times the switching frequency of the inverter transformer, and the sampling duration is not less than one complete power frequency cycle.
[0030] At each sampling moment, the magnetic flux density sensing unit outputs magnetic flux density components in three orthogonal directions. The instantaneous leakage magnetic flux density amplitude at the sampling moment is equal to the square root of the sum of the squares of the three directional components. The instantaneous leakage magnetic flux density vector direction at the sampling moment is represented by a three-dimensional spatial direction angle. The cosine of the angle between the instantaneous vector direction and the three orthogonal coordinate axes is equal to the component in the corresponding direction divided by the instantaneous leakage magnetic flux density amplitude.
[0031] Within the complete sampling duration, the arithmetic mean of the instantaneous leakage flux density amplitude at all sampling moments is calculated, and the result is used as the leakage flux density amplitude of each peripheral calibration point. The vector direction is obtained through the following steps: First, construct the unit direction vector at each sampling moment, which is a three-dimensional vector composed of the three directional components divided by the instantaneous amplitude; then, sum the unit direction vectors at all sampling moments; finally, normalize the summed vector to obtain the vector direction of each peripheral calibration point.
[0032] Reference Figure 2 As shown, in this embodiment, determining the main radiation direction and dispersion angle range of the diffuse leakage flux includes: taking the peripheral calibration measurement point with the largest leakage flux density amplitude as the central measurement point, and taking the vector direction corresponding to the central measurement point as the main radiation direction of the diffuse leakage flux.
[0033] The leakage flux density amplitude is read sequentially along the clockwise and counterclockwise directions on both sides of the main radiation direction, and the ratio of the leakage flux density amplitude at the current reading point to the maximum leakage flux density amplitude is calculated.
[0034] If the ratio is greater than or equal to the preset attenuation ratio, the search continues to the next measurement point on the same side.
[0035] If the ratio is less than the preset attenuation ratio for the first time, the same-side search will stop, and the next adjacent measurement point that meets the ratio condition on the same side will be marked as the diffusion boundary measurement point.
[0036] The angular range enclosed by connecting the central measuring point and the marked diffusion boundary measuring points on both sides to the geometric center of the air gap is determined as the diffusion spread angle range.
[0037] In this embodiment, the preset attenuation ratio is determined as follows: during the transformer type test phase, the leakage flux density amplitude of all peripheral calibration measurement points is collected under rated load conditions and arranged in descending order.
[0038] The amplitude attenuation rate between adjacent measurement points is calculated sequentially in descending order, and the amplitude attenuation rate at the first occurrence of an attenuation rate jump is taken as the reference attenuation jump rate; wherein, the amplitude attenuation rate is the ratio of the difference between the amplitude of the previous measurement point and the amplitude of the next measurement point to the amplitude of the previous measurement point, and the attenuation rate jump determination condition is that the current amplitude attenuation rate exceeds twice the average amplitude attenuation rate of all preceding items.
[0039] Obtain the percentage of repeatability measurement error recorded in the factory calibration report of the magnetic flux density sensing unit. The percentage of repeatability measurement error represents the ratio of the standard deviation of the output value of the sensor under the same magnetic field conditions to the full-scale output value. The sum of the reference attenuation jump rate and the percentage of repeatability measurement error is used as the preset attenuation ratio.
[0040] The magnetic circuit guidance module plans a guidance path from the air gap dispersion source center to the low magnetic resistance channel inlet interception surface based on the main radiation direction and dispersion spread angle range. It divides multiple transition sections with monotonically decreasing magnetic resistance values along the guidance path to form a directional magnetic potential gradient, which drives the dispersion leakage flux to contract directionally along the guidance path and merge into the low magnetic resistance channel.
[0041] In this embodiment, the planning of the guiding path from the air gap dispersion source center to the low magnetic reluctance channel inlet interception surface includes: taking the geometric center of the unsaturated air gap region as the dispersion source center and the main radiation direction as the reference axis, calculating the spatial equivalent permeability step by step from the dispersion source center outward along the reference axis in the space between the inner wall of the transformer shell and the main magnetic circuit of the iron core. Specifically, extending outward along the reference axis from the dispersion source center, the minimum radial distance between the outer edge of the unsaturated air gap region and the inner wall of the transformer shell is taken. As a fixed distance step, it advances step by step at a fixed distance step size. At each step position, the sampling section is a plane centered on the reference axis and perpendicular to the reference axis.
[0042] The sampling section is divided into two-dimensional grids, and the medium material type of each grid cell is labeled. The medium material types include iron core silicon steel sheets, air gap fillers, and internal filling media of the shell.
[0043] The number of grid cells occupied by each type of medium material is counted, and the number of grid cells is multiplied by the area of a unit grid cell to obtain the actual area of each type of medium material on the sampling section.
[0044] Multiply the intrinsic permeability of each dielectric material by its actual area on the sampling section, sum the results for all dielectric materials, and then divide the sum by the total area of all dielectric materials on the sampling section to obtain the spatial equivalent permeability at the corresponding step position.
[0045] Calculate the change in permeability of each step position relative to the previous step position, and simultaneously obtain the arithmetic mean and standard deviation of the changes in permeability at the traversed step positions. When the difference between the change in permeability at a certain step position and the arithmetic mean of all previous changes is greater than a preset multiple (3 times) of the standard deviation, the step position is determined as the position of the low magnetic reluctance channel entrance interception surface.
[0046] A guiding path centerline is formed by extending from the dispersion source center along the main radiation direction to the interception surface at the entrance of the low magnetic reluctance channel. Using the centerline as an axis of symmetry, the cross-sectional width is determined by expanding outwards at each location according to the dispersion spread angle range, thus forming the guiding path. The cross-sectional width is defined as the radial dimension of the cross-section determined by expanding outwards at a certain location along the guiding path, with the centerline as the axis of symmetry and the dispersion spread angle range.
[0047] In this embodiment, the division of multiple transition sections with monotonically decreasing magnetoresistance values along the guidance path includes: dividing the path from the diffusion source core to the low magnetoresistance channel entrance interception surface into several transition sections in an equal magnetic potential difference manner along the extension direction of the guidance path.
[0048] Taking the transition section located at the edge of the unsaturated air gap region as the starting section, the weighted average of the equivalent magnetoresistance value of the unsaturated air gap region and the magnetoresistance value of the filling medium surrounding the unsaturated air gap region is used as the magnetoresistance value of the starting section. The weighting is as follows: the thickness of the unsaturated air gap region is taken as the characteristic length; the ratio of the volume within one air gap thickness from the edge of the starting section to the total volume of the starting section is used as the weight of the equivalent magnetoresistance value of the air gap; the remaining volume percentage is used as the weight of the magnetoresistance value of the filling medium, and the sum of the two weights is 1. The air gap thickness is a known design parameter, and the volume of the starting section is given by the product of its length and cross-sectional area.
[0049] The transition section adjacent to the interception surface of the low magnetic reluctance channel entrance is taken as the termination section, and the magnetic reluctance value at the entrance of the low magnetic reluctance channel is taken as the magnetic reluctance value of the termination section. Specifically, the magnetic reluctance value at the entrance of the low magnetic reluctance channel is given by dividing the equivalent length of the channel entrance along the magnetic path direction by the product of the permeability of the low magnetic reluctance channel material and the cross-sectional area of the channel entrance.
[0050] The magnetoresistance values of each intermediate transition section between the starting section and the ending section are determined by nonlinear interpolation along the guiding direction according to the section number, and the magnetoresistance values of adjacent sections decrease monotonically along the guiding direction.
[0051] It should be noted that the equal magnetic potential difference segmentation process is as follows: obtain the nominal value of the magnetic permeability of the material used in the transition section and its maximum relative deviation in mass production; multiply the maximum relative deviation by the initial magnetic potential value at the edge of the air gap region to obtain the unit magnetic potential difference step size; define the unit magnetic potential difference step size as the amount of magnetic potential difference change corresponding to the minimum resolvable change in magnetic reluctance that the transition section material can achieve in the manufacturing process; divide the total magnetic potential difference by the unit magnetic potential difference step size, and round down the quotient to obtain the number of transition sections; divide the total magnetic potential difference into the corresponding number of equal parts along the centerline of the guide path, with each part corresponding to one transition section, and the magnetic potential difference at both ends of each transition section being an integer multiple of the unit magnetic potential difference step size.
[0052] The nonlinear interpolation determination process includes: calculating the ratio of the magnetoresistance value of the termination section to the magnetoresistance value of the starting section, and raising the ratio to the power of the total number of sections to obtain the common ratio of the magnetoresistance values of adjacent sections.
[0053] Starting with the magnetic reluctance value of the initial segment, the magnetic reluctance value of the current segment is multiplied by a common ratio in the direction from the initial segment to the final segment to obtain the magnetic reluctance value of the next segment, until the segment preceding the final segment is calculated.
[0054] In this embodiment, the equivalent magnetoresistance value of the unsaturated air gap region is obtained in the following way.
[0055] Based on the air gap thickness, air gap cross-sectional area, and relative permeability of the air gap medium in the unsaturated air gap region, the magnetoresistance value of the unsaturated air gap region in the direction of magnetic circuit length is calculated and used as the equivalent magnetoresistance reference value. Specifically, the equivalent magnetoresistance reference value is given by dividing the air gap thickness of the unsaturated air gap region by the product of the air gap cross-sectional area and the relative permeability of the air gap medium.
[0056] Under no-load conditions with rated excitation applied to the primary winding and the secondary winding open, the leakage flux density amplitude of each peripheral calibration point in the unsaturated air gap region is collected, and the arithmetic mean of the leakage flux density amplitude of all peripheral calibration points is calculated as the average of the measured amplitude.
[0057] Under the same no-load conditions, the amplitude simulation values at corresponding positions of each peripheral calibration measurement point are obtained through electromagnetic field finite element simulation based on the equivalent magnetoresistive reference value. The arithmetic mean of the amplitude simulation values is calculated as the average of the simulation amplitude.
[0058] The equivalent magnetoresistive value of the unsaturated air gap region is obtained by multiplying the ratio of the simulated average amplitude to the measured average amplitude by the equivalent magnetoresistive reference value.
[0059] The efficiency calculation module calculates the ratio of the flux reinjection at the low magnetic reluctance channel outlet to the total amount of diffuse leakage flux in the unsaturated air gap region, which is used as the leakage flux capture efficiency.
[0060] In this embodiment, the total amount of diffuse leakage flux in the unsaturated air gap region is obtained through the following process.
[0061] A unit sphere is constructed with the geometric center of the unsaturated air gap region as the center and the unit length as the radius. The outer calibration points are then projected radially onto the unit sphere to obtain the spherical projection points of each outer calibration point.
[0062] Based on the nearest neighbor relationships between each spherical projection point, spherical region partitioning is performed on each spherical projection point, dividing the unit sphere into spherical polygonal regions corresponding one-to-one with each spherical projection point. The spherical region partitioning rule is as follows: for each spherical projection point, a spherical polygonal region is defined on the sphere, where the spherical geodesic distance from any point within the region to the corresponding projection point is less than or equal to the spherical geodesic distance to any other projection point. Each region is non-overlapping and covers the entire sphere. The partitioning is completed by calculating the intersection of the perpendicular bisectors of the great circles connecting adjacent projection points. Each peripheral calibration point obtains a unique spherical polygonal region, and the area of this region is the spherical area of the corresponding measurement point on the unit sphere.
[0063] Multiply the spherical area of each spherical polygon region by the square of the distance from the corresponding outer calibration point to the center of the sphere to obtain the effective sampling area of the corresponding outer calibration point.
[0064] Multiply the leakage flux density amplitude of each peripheral calibration point by its effective sampling area and sum them to obtain the total diffuse leakage flux in the unsaturated air gap region.
[0065] When the leakage flux capture efficiency is less than the preset efficiency threshold, the feedback adjustment module selects the arrangement density or magnetic reluctance gradient of the transition section as the adjustment target based on the degree of efficiency deviation and the spatial constraints of the transition section, implements corresponding adjustment measures, and re-executes the efficiency calculation module until the capture efficiency meets the target or reaches the maximum number of iterations.
[0066] In this embodiment, the adjustment target is selected in the following manner: the difference between the current leakage flux capture efficiency and the preset efficiency threshold is divided by the preset efficiency threshold to obtain the degree of efficiency deviation; the preset efficiency threshold is determined in the following manner: according to the electromagnetic compatibility standards that the transformer needs to meet, the allowable radiated magnetic field strength limit at a specified distance is obtained; through electromagnetic field finite element simulation, the peak value of the radiated magnetic field strength generated by the diffuse leakage flux in the unsaturated air gap region at the same distance under the condition of no magnetic shielding is calculated; the ratio of the allowable limit to the simulated peak value is used as the allowable leakage flux ratio, and the preset efficiency threshold is obtained by subtracting the allowable leakage flux ratio from 1.
[0067] The cross-sectional area is calculated based on the cross-sectional width and the preset cross-sectional shape. If the cross-sectional shape involves height, the pre-configured spatial height value between the transformer core column and the shell is directly retrieved. The length of each transition section in the direction of the guide path extension is multiplied by the cross-sectional area to obtain the spatial volume occupied by each transition section. The length of the transition section is equal to the arc length of the centerline between the starting point and the ending point of the section determined by the equal magnetic potential difference division method.
[0068] The available layout space margin is obtained by subtracting the sum of the space volumes occupied by the already laid transition sections from the total available filling space volume along the guide path inside the transformer casing.
[0069] Take the minimum spatial volume of the existing transition sections as the minimum space required to add a new transition section.
[0070] If the available layout space margin is greater than or equal to the minimum space amount, and the efficiency deviation is greater than the ratio of the available layout space margin to the total available filling space volume, then the layout density of the transition section is selected as the adjustment target; otherwise, the magnetic reluctance decreasing gradient of the transition section is selected as the adjustment target.
[0071] Reference Figure 3 As shown, in this embodiment, when the arrangement density of the transition section is selected as the adjustment object, the following adjustment measures are implemented: the available arrangement space margin is divided by the minimum space amount and then rounded down to obtain the number of sections that can be increased.
[0072] The absolute difference between the magnetoresistance value of each transition section and the magnetoresistance of the next transition section along the guidance direction is calculated and used as the magnetoresistance reduction gradient magnitude corresponding to each transition section. The transition section with the largest magnitude is determined as the target segment. The reason for prioritizing the segment with the largest magnetoresistance reduction gradient magnitude is that the magnetoresistance changes most drastically in this segment. Dividing it into more sub-segments can soften the magnetoresistance transition, reduce the magnitude of magnetoresistance abrupt changes between adjacent sub-segments, and facilitate the smooth migration of leakage flux.
[0073] The target segment is divided into several sub-segments, the total number of which equals 1 plus the number of expandable segments. The magnetoresistive value of each sub-segment is linearly interpolated between the original starting and ending magnetoresistive values of the target segment, and the magnetoresistive value of each sub-segment decreases monotonically along the guiding direction. The linear interpolation is performed according to the following formula:
[0074] ;
[0075] In the formula, Indicates the first The magnetoresistance value of each sub-segment For each sub-segment, , To increase the number of segments, These are the original starting and ending magnetoresistance values of the target segment, respectively.
[0076] The step size represents the arithmetic increment of the magnetoresistive values between two adjacent sub-segments, which discretizes the difference between the initial and final magnetoresistive values according to the sub-segment intervals.
[0077] This formula uses linear interpolation to distribute the magnetic reluctance values of each sub-segment at equal arithmetic intervals between the initial and final magnetic reluctance values, so that the magnetic reluctance increases at equal steps along the numbering, thus ensuring a smooth transition of magnetic reluctance between adjacent segments after local densification.
[0078] In this embodiment, when the magnetoresistance reduction gradient of the transition section is selected as the adjustment target, the following adjustment measures are implemented: the difference between the equivalent magnetoresistance value of the unsaturated air gap region and the magnetoresistance value of the current starting section is divided by the magnetoresistance value of the current starting section to obtain the percentage increase in the magnetoresistance value of the starting section.
[0079] Divide the difference between the current magnetoresistance value of the termination section and the minimum magnetoresistance value of the material inside the low magnetoresistance channel by the current magnetoresistance value of the termination section to obtain the percentage reduction in the magnetoresistance value of the termination section.
[0080] The efficiency deviation is multiplied by the upward and downward adjustment percentages, respectively, to determine the adjustment range of the starting segment and the adjustment range of the ending segment.
[0081] If the adjustment amplitude of the starting section is greater than that of the ending section, the magnetic reluctance value of the starting section is increased by the maximum percentage that can be increased; otherwise, the magnetic reluctance value of the ending section is decreased by the maximum percentage that can be decreased.
[0082] Between the adjusted starting and ending segment magnetoresistance values, while maintaining the total number of segments, the magnetoresistance values of all segments are re-allocated using nonlinear interpolation. This nonlinear interpolation method is consistent with the nonlinear interpolation method used when dividing multiple monotonically decreasing transition segments along the guide path. This nonlinear interpolation method is selected based on the spatial attenuation characteristics of leakage flux density along the guide path, ensuring that the magnetoresistance decrease gradient between adjacent segments near the diffusion source center is greater than that between adjacent segments far from the diffusion source center.
[0083] It should be noted that the maximum number of iterations can be set to 10 for example, in order to prevent infinite loops when convergence is not possible due to physical space or material magnetic resistance limitations. If the maximum number of iterations is reached but the target is still not met, a warning message will be output to prompt the designer to re-evaluate the preset efficiency threshold or the geometry of the guide path.
[0084] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.
Claims
1. An electromagnetic self-shielded inverter transformer, characterized in that, include: The leakage flux measurement module determines the main radiation direction and dispersion angle range of the diffuse leakage flux based on the amplitude and vector direction of the leakage flux density at the calibration point outside the unsaturated air gap region. The magnetic circuit guidance module plans a guidance path from the air gap dispersion source center to the low magnetic resistance channel inlet interception surface based on the main radiation direction and dispersion spread angle range. It divides multiple transition sections with monotonically decreasing magnetic resistance values along the guidance path to form a directional magnetic potential gradient, which drives the dispersion leakage flux to contract directionally along the guidance path and merge into the low magnetic resistance channel. The efficiency calculation module calculates the ratio of the magnetic flux reinjection at the low magnetic reluctance channel outlet to the total amount of diffuse leakage magnetic flux in the unsaturated air gap region, which is used as the leakage magnetic flux capture efficiency. The feedback adjustment module, when the leakage flux capture efficiency is less than the preset efficiency threshold, selects the arrangement density or magnetic reluctance reduction gradient of the transition section as the adjustment object according to the degree of efficiency deviation and the spatial constraints of the transition section, implements corresponding adjustment measures, and re-executes the efficiency calculation module until the capture efficiency meets the target or reaches the maximum number of iterations.
2. The electromagnetic self-shielded inverter transformer according to claim 1, characterized in that, The determination of the principal radiation direction and dispersion angle range of the diffuse leakage flux includes: The outer calibration point with the largest leakage flux density amplitude is taken as the center measurement point, and the vector direction corresponding to the center measurement point is taken as the main radiation direction of the diffuse leakage flux. The leakage flux density amplitude is read sequentially along the clockwise and counterclockwise directions on both sides of the main radiation direction, and the ratio of the leakage flux density amplitude at the current reading point to the maximum leakage flux density amplitude is calculated. If the ratio is greater than or equal to the preset attenuation ratio, the search continues to the next measurement point on the same side; If the ratio is less than the preset attenuation ratio for the first time, the same-side search will stop, and the previous measurement point that satisfies the ratio condition on the same side will be marked as the diffusion boundary measurement point. The angular range enclosed by connecting the central measuring point and the marked diffusion boundary measuring points on both sides to the geometric center of the air gap is determined as the diffusion spread angle range.
3. The electromagnetic self-shielded inverter transformer according to claim 2, characterized in that, The preset attenuation ratio is determined as follows: During the transformer type test phase, leakage flux density amplitudes of all peripheral calibration measurement points were collected under rated load conditions and arranged in descending order; The amplitude attenuation rate between adjacent measuring points is calculated sequentially in descending order, and the amplitude attenuation rate at the first occurrence of an attenuation rate jump is taken as the reference attenuation jump rate. Obtain the percentage of repeatability measurement error recorded in the factory calibration report of the magnetic flux density sensing unit, and use the sum of the reference attenuation jump rate and the percentage of repeatability measurement error as the preset attenuation ratio.
4. The electromagnetic self-shielded inverter transformer according to claim 1, characterized in that, The planned guiding path from the air gap dispersion source core to the low magnetic reluctance channel inlet interception surface includes: Using the geometric center of the unsaturated air gap region as the diffusion source center and the main radiation direction as the reference axis, the spatial equivalent permeability is calculated step by step from the diffusion source center outward along the reference axis in the space between the inner wall of the transformer shell and the main magnetic circuit of the iron core. The change in permeability at each step position relative to the previous step position is calculated, and the arithmetic mean and standard deviation of all changes at the traversed step positions are obtained simultaneously. When the difference between the change in magnetic permeability at a certain step position and the arithmetic mean of all previous changes is greater than a preset multiple of the standard deviation, that step position is determined as the position of the low magnetic reluctance channel inlet interception surface. The centerline of the guiding path is formed by extending from the diffusion source center along the main radiation direction to the interception surface at the entrance of the low magnetic resistance channel. With the centerline as the axis of symmetry, the cross-sectional width is determined by expanding to both sides at each position according to the diffusion spread angle range, thus forming the guiding path.
5. The electromagnetic self-shielded inverter transformer according to claim 1, characterized in that, The guide path is divided into multiple monotonically decreasing transition sections, including: From the diffusion source core to the low magnetic resistance channel entrance interception surface, along the extension direction of the guide path, it is divided into several transition sections in the manner of equal magnetic potential difference; Taking the transition section located at the edge of the unsaturated air gap region as the starting section, the weighted average of the equivalent magnetoresistance value of the unsaturated air gap region and the magnetoresistance value of the filling medium around the unsaturated air gap region is taken as the magnetoresistance value of the starting section. The transition section adjacent to the interception surface at the entrance of the low magnetic reluctance channel is taken as the termination section, and the magnetic reluctance value at the entrance of the low magnetic reluctance channel is taken as the magnetic reluctance value of the termination section. The magnetoresistance values of each intermediate transition section between the starting section and the ending section are determined by nonlinear interpolation along the guiding direction according to the section number, and the magnetoresistance values of adjacent sections decrease monotonically along the guiding direction.
6. The electromagnetic self-shielded inverter transformer according to claim 5, characterized in that, The equivalent magnetoresistance value of the unsaturated air gap region is obtained through the following method: Based on the air gap thickness, air gap cross-sectional area and relative permeability of the air gap medium in the unsaturated air gap region, the magnetic reluctance value in the direction of the magnetic circuit length of the unsaturated air gap region is calculated and used as the equivalent magnetic reluctance reference value. Under no-load conditions with rated excitation applied to the primary winding and the secondary winding open, the leakage flux density amplitude of each peripheral calibration point in the unsaturated air gap region is collected, and the arithmetic mean of the leakage flux density amplitude of all peripheral calibration points is calculated as the average of the measured amplitude. Under the same no-load conditions, the amplitude simulation values at corresponding positions of each peripheral calibration measurement point are obtained through electromagnetic field finite element simulation based on the equivalent magnetoresistive reference value. The arithmetic mean of the amplitude simulation values is calculated as the average of the simulation amplitude. The equivalent magnetoresistive value of the unsaturated air gap region is obtained by multiplying the ratio of the simulated average amplitude to the measured average amplitude by the equivalent magnetoresistive reference value.
7. The electromagnetic self-shielded inverter transformer according to claim 1, characterized in that, The total diffuse leakage flux in the unsaturated air gap region is obtained through the following process: Construct a unit sphere with the geometric center of the unsaturated air gap region as the center and the unit length as the radius. Project each peripheral calibration point radially onto the unit sphere to obtain the spherical projection points of each peripheral calibration point. Based on the nearest neighbor relationship between each spherical projection point, the unit sphere is divided into spherical polygon regions that correspond one-to-one with each spherical projection point. Multiply the spherical area of each spherical polygon region by the square of the distance from the corresponding outer calibration point to the center of the sphere to obtain the effective sampling area of the corresponding outer calibration point. Multiply the leakage flux density amplitude of each peripheral calibration point by its effective sampling area and sum them to obtain the total diffuse leakage flux in the unsaturated air gap region.
8. The electromagnetic self-shielded inverter transformer according to claim 1, characterized in that, The adjustment targets are selected in the following manner: The difference between the current leakage flux capture efficiency and the preset efficiency threshold is divided by the preset efficiency threshold to obtain the degree of efficiency deviation. Calculate the volume of space occupied by each transition section based on its length and cross-sectional width in the direction of the guide path extension. The available layout space margin is obtained by subtracting the sum of the space volumes occupied by the already laid transition sections from the total available filling space volume inside the transformer casing along the guide path direction. Take the minimum spatial volume of the existing transition sections as the minimum space required to add a new transition section; If the available layout space margin is greater than or equal to the minimum space amount, and the efficiency deviation is greater than the ratio of the available layout space margin to the total available filling space volume, then the layout density of the transition section is selected as the adjustment target; otherwise, the magnetic reluctance decreasing gradient of the transition section is selected as the adjustment target.
9. An electromagnetic self-shielded inverter transformer according to claim 8, characterized in that, when the arrangement density of the transition section is selected as the adjustment target, the following adjustment measures are implemented: Divide the available layout space margin by the minimum space amount and round down to get the number of additional segments; Calculate the absolute difference between the magnetoresistance value of each transition section and the magnetoresistance of the next transition section along the guidance direction, and use it as the magnetoresistance decreasing gradient magnitude corresponding to each transition section. The transition section with the largest magnitude is determined as the target splitting section. The target segment is divided into several sub-segments. The total number of sub-segments is equal to 1 plus the number of segments that can be added. The magnetoresistive value of each sub-segment is linearly interpolated between the original starting magnetoresistive value and the ending magnetoresistive value of the target segment. The magnetoresistive value of each sub-segment decreases monotonically along the guiding direction.
10. An electromagnetic self-shielded inverter transformer according to claim 8, characterized in that, When the magnetoresistance decrease gradient in the transition section is selected as the adjustment target, the following adjustment measures are implemented: Divide the difference between the equivalent magnetoresistance value of the unsaturated air gap region and the magnetoresistance value of the current starting section by the magnetoresistance value of the current starting section to obtain the percentage increase in the magnetoresistance value of the starting section. Divide the difference between the current magnetoresistance value of the termination section and the minimum magnetoresistance value of the material inside the low magnetoresistance channel by the current magnetoresistance value of the termination section to obtain the percentage reduction in the magnetoresistance value of the termination section. Multiply the efficiency deviation by the upward and downward adjustment percentages respectively to determine the adjustment range of the starting segment and the adjustment range of the ending segment; If the adjustment amplitude of the starting section is greater than that of the ending section, the magnetic reluctance value of the starting section is increased by the maximum percentage that can be increased; otherwise, the magnetic reluctance value of the ending section is decreased by the maximum percentage that can be decreased. Between the adjusted starting segment magnetoresistance value and the ending segment magnetoresistance value, while keeping the total number of segments unchanged, the magnetoresistance values of all segments are redistributed nonlinearly through interpolation.