A magnetic circuit analysis method of a permanent magnetic field sleep magnetic therapeutic instrument

Abstract

This invention relates to the field of magnetic therapy equipment design technology, and discloses a magnetic circuit analysis method for a permanent magnetic field sleep magnetic therapy device. The method includes stimulation mode design, static magnetic circuit operating point selection, self-demagnetization effect guidance design, and finite element simulation verification. The stimulation mode design includes static and dynamic modes. Static magnetic circuit operating point selection determines the maximum magnetic energy accumulation point by constructing a load line using characteristic points of the demagnetization curve and correcting the operating point coordinate ratio. The self-demagnetization effect guidance design employs a closed magnetic circuit structure, reverse compensation magnetic ring installation, and magnetic domain stabilization treatment. Finite element simulation verification constructs a coupling model between the magnetic therapy device and human tissue. These four parts are executed sequentially and interconnected to form a closed loop. This method solves the problems of low magnetic energy utilization and significant self-demagnetization impact in traditional magnetic circuits, achieving precise magnetic field focusing and stable magnetic circuit operation, thus meeting the needs of sleep therapy.

Description

Technical Field

[0001] This invention relates to the field of magnetic therapy equipment design technology, specifically to a magnetic circuit analysis method for a permanent magnetic field sleep magnetic therapy device. Background Technology

[0002] With the increasing number of people suffering from sleep problems, transcranial magnetic stimulation (TMS) technology in physical therapy has been widely used due to its advantages such as being painless and having no side effects. Permanent magnetic field sleep magnetic therapy devices have become a research hotspot due to the stable magnetic field and heat-free characteristics of their main permanent magnets; however, magnetic circuit design is the core bottleneck in their performance. In existing magnetic circuit design methods, the selection of the main permanent magnet's operating point does not fully incorporate the material's maximum magnetic energy product characteristics, resulting in low magnetic energy utilization. Furthermore, the problem of magnetic field attenuation caused by self-demagnetization has not been effectively addressed. During long-term operation, the magnetic field stability is poor, making it impossible to accurately target the raphe nucleus region of the brain, a core area for sleep regulation, thus severely affecting the therapeutic effect.

[0003] Based on the above problems, there is an urgent need for a magnetic circuit analysis method that can optimize the operating point of the main permanent magnet and suppress the self-demagnetization effect. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a magnetic circuit analysis method for a permanent magnetic field sleep magnetic therapy device. This method includes stimulation mode design, static magnetic circuit operating point selection, self-demagnetization effect guidance design, and finite element simulation verification. The stimulation mode design comprises a static mode and a dynamic mode. The static mode provides a stable magnetic field, while the dynamic mode provides an alternating magnetic field. The static magnetic circuit operating point selection constructs a load line using characteristic points of the demagnetization curve. The intersection of the load line and the demagnetization curve is the maximum magnetic energy product point, and the operating point coordinate ratio is corrected by combining magnetic circuit structure parameters. The self-demagnetization effect guidance design employs a closed magnetic circuit structure, a compensating magnetic ring installation, and magnetic domain stabilization treatment. The magnetic field direction of the compensating magnetic ring is opposite to the self-demagnetization direction of the main permanent magnet. The finite element simulation verification constructs a coupling model between the magnetic therapy device and human tissue. These four parts are executed sequentially and interconnected, forming a complete closed loop for magnetic circuit design and analysis.

[0005] Preferably, the static mode achieves continuous change of magnetic induction intensity by adjusting the air gap between the main permanent magnet and the magnetic plate, the dynamic mode generates a low-frequency alternating magnetic field by driving the permanent magnet block to rotate around the axis through a stepper motor, and the speed of the stepper motor is adjusted by the control system to achieve continuous adjustment of the frequency of the alternating magnetic field. The stimulation mode design also includes adaptive mode switching, which determines the target stimulation mode based on the collected human tissue impedance value and the input insomnia degree parameter.

[0006] More preferably, in the selection of the static magnetic circuit operating point, the characteristic points of the demagnetization curve are the intersection points of the demagnetization curve and the magnetic induction intensity coordinate axis and the intersection points of the demagnetization curve and the magnetic field intensity coordinate axis. The magnetic circuit structure parameters include air gap parameters, main permanent magnet parameters, magnetic flux utilization coefficient and magnetic reluctance coefficient. The air gap parameters include the air gap cross-sectional area and the air gap length. The main permanent magnet parameters include the main permanent magnet cross-sectional area and the main permanent magnet effective length.

[0007] More preferably, the closed magnetic circuit structure is composed of a magnetic core and a magnetic conductive plate, the magnetic conductive plate is made of electrical pure iron, the compensating magnetic ring is nested in the magnetic circuit output end, the magnetic domain stabilization treatment is performed by vacuum annealing the magnetic core, and the magnetic circuit output end is on the side facing the human head.

[0008] More preferably, the working point coordinate ratio correction adopts a working point coordinate ratio correction formula. The working point coordinate ratio correction formula is calculated by comprehensively considering the air gap length, the cross-sectional area of ​​the main permanent magnet, the magnetic flux utilization coefficient, the relative permeability of the yoke, the effective length of the main permanent magnet, the cross-sectional area of ​​the air gap, the magnetic reluctance coefficient, the actual working temperature of the magnetic circuit, and the standard working temperature of the magnetic circuit, so as to eliminate the influence of leakage flux and temperature changes on the stability of the working point.

[0009] In a further preferred embodiment, the self-demagnetizing effect suppression employs a self-demagnetizing dynamic compensation coefficient formula. This formula integrates the cumulative working time of the magnetic therapy device, the magnetic domain attenuation coefficient, the corrected working point coordinate ratio, the inherent stabilization time of the main permanent magnet's magnetic domain, the average permeability of human head tissue, and the vacuum permeability, thereby achieving dynamic quantitative compensation for the self-demagnetizing effect.

[0010] In a further preferred embodiment, the magnetic energy utilization efficiency calculation adopts the magnetic energy utilization efficiency formula, which combines the maximum magnetic energy product of the main permanent magnet, the corrected working point coordinate ratio, the self-demagnetizing dynamic compensation coefficient, the cross-sectional area of ​​the main permanent magnet, the effective length of the main permanent magnet, the vacuum permeability, the air gap magnetic field strength, the air gap cross-sectional area, the air gap length, and the magnetic circuit leakage correction coefficient to achieve an accurate assessment of the magnetic energy utilization efficiency.

[0011] More preferably, in the finite element simulation verification, the magnetic therapy device model includes a magnetic core, a coil, and a compensating magnetic ring. The magnetic core is made of neodymium iron boron permanent magnet material, and the coil is wound with copper wire. The human tissue coupling model includes a layered structure of skin, fat, muscle, and bone. The finite element simulation verification includes stimulation mode simulation, operating point simulation, and self-demagnetization simulation. The stimulation mode simulation verifies the magnetic field distribution under different stimulation modes, the operating point simulation verifies the change in magnetic induction intensity of the magnetic core under different currents, and the self-demagnetization simulation verifies the magnetic field attenuation law with and without compensation.

[0012] More preferably, the main permanent magnet is made of N50NdFeB permanent magnet material, the main permanent magnet is processed into permanent magnet blocks, the permanent magnet blocks are uniformly distributed along the circumference of the stepper motor axis, the closed magnetic circuit structure designed with self-demagnetizing effect includes a magnetic yoke, the magnetic yoke is processed into a ring structure, and the compensation magnetic ring is made of SmCo27 samarium cobalt magnetic material.

[0013] More preferably, the adaptive mode switching includes automatic switching and manual switching. The automatic switching is executed by the microcontroller based on the human tissue impedance value and insomnia level parameters. The microcontroller receives data collected by the magnetic field detection module and the impedance detection module. The magnetic field detection module uses a Hall sensor, and the impedance detection module uses silver electrodes to construct an AC impedance circuit. The manual switching is achieved through a button on the side of the magnetic therapy device.

[0014] Technical Effects: This invention determines the maximum magnetic energy product point of the main permanent magnet and corrects the working point coordinate ratio using the load line method. Combined with a reverse compensation magnetic ring and a closed magnetic circuit structure, it suppresses the self-demagnetizing effect, solving the core problems of low magnetic energy utilization and magnetic field attenuation in existing technologies. The magnetic circuit design forms a closed loop, precisely focusing the magnetic field on the midline core region, resulting in strong long-term operational stability and meeting the magnetic stimulation needs of sleep therapy. Attached Figure Description

[0015] Figure 1 This is a closed-loop connection block diagram of the main module for magnetic circuit analysis of the permanent magnetic field sleep magnetic therapy device of the present invention;

[0016] Figure 2 This is a diagram showing the core components and related blocks of the main module for magnetic circuit analysis of the permanent magnetic field sleep magnetic therapy device of this invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] In existing technologies, the selection of the operating point of the main permanent magnet lacks a scientific quantitative method, the magnetic energy cannot be fully released, and there is a lack of effective means to suppress the self-demagnetization effect, resulting in unstable magnetic circuit performance.

[0019] Based on this, please refer to Figures 1-2This invention provides a magnetic circuit analysis method for a permanent magnetic field sleep magnetic therapy device, including stimulation mode design, static magnetic circuit operating point selection, self-demagnetization effect guidance design, and finite element simulation verification. The stimulation mode design includes a static mode and a dynamic mode. The static mode provides a stable magnetic field, and the dynamic mode provides an alternating magnetic field. The static magnetic circuit operating point selection constructs a load line through the characteristic points of the demagnetization curve. The intersection of the load line and the demagnetization curve is the maximum magnetic energy product point. The operating point coordinate ratio is corrected by combining the magnetic circuit structure parameters. The self-demagnetization effect guidance design adopts a closed magnetic circuit structure, a compensating magnetic ring installation, and magnetic domain stabilization treatment. The magnetic field direction of the compensating magnetic ring is opposite to the self-demagnetization direction of the main permanent magnet. The finite element simulation verification constructs a coupling model between the magnetic therapy device and human tissue. The four parts are executed sequentially and linked together to form a complete closed loop for magnetic circuit design and analysis.

[0020] The core of this technical solution lies in the construction of a multi-stage collaborative systematic design process, where each part does not exist in isolation but forms a closely linked closed loop. The stimulation mode design provides clear application scenarios and performance requirements for the entire magnetic circuit analysis. The static mode is designed for scenarios requiring continuous and stable magnetic stimulation, while the dynamic mode is adapted to the need for periodic alternating magnetic stimulation. The setting of these two modes provides clear performance indicators for subsequent operating point selection and self-demagnetization suppression. Static magnetic circuit operating point selection is crucial for efficient magnetic energy utilization. Its innovation lies in breaking through the traditional experience-based method of selecting the operating point. By constructing a load line through the characteristic points of the demagnetization curve, the maximum magnetic energy accumulation point is precisely locked. This process is based on the inherent magnetic properties of permanent magnet materials, ensuring that the main permanent magnet operates in the state of highest magnetic energy output efficiency. Furthermore, the operating point coordinate ratio is corrected by combining the actual structural parameters of the magnetic circuit, ensuring that the operating point selection conforms to both material characteristics and actual magnetic circuit conditions. The self-demagnetizing effect-oriented design achieves suppression through a three-dimensional synergy: a closed magnetic circuit structure reduces magnetic flux leakage, a compensating magnetic ring directly counteracts part of the self-demagnetizing effect with a reverse magnetic field, and magnetic domain stabilization improves stability by addressing the internal structure of the magnetic core. These three elements form a three-dimensional suppression system, overcoming the limitations of traditional single-structure self-demagnetization suppression. Finite element simulation verifies the construction of a coupled model between the magnetic therapy device and human tissue, rather than simply simulating the magnetic circuit. This realistically simulates the propagation and effect of the magnetic field on the human head, providing precise feedback for the design of the first three stages and ensuring that the entire magnetic circuit design meets performance requirements and is suitable for practical application scenarios. The four parts proceed sequentially, with the design results of the previous stage serving as input for the next, and the simulation verification results of the next stage optimizing the parameters of the previous stage, forming a complete closed loop and ensuring the scientific validity and reliability of the magnetic circuit design.

[0021] In existing technologies, stimulation mode switching is mostly fixed and cannot be accurately adapted to individual user differences and actual needs. The adjustment of magnetic field parameters also lacks flexibility.

[0022] Based on this, the static mode achieves continuous change of magnetic induction intensity by adjusting the air gap between the main permanent magnet and the magnetic plate. The dynamic mode generates a low-frequency alternating magnetic field by driving the permanent magnet block to rotate around the axis through a stepper motor. The speed of the stepper motor is adjusted by the control system to achieve continuous adjustment of the frequency of the alternating magnetic field. The stimulation mode design also includes adaptive mode switching. The adaptive mode switching determines the target stimulation mode based on the collected human tissue impedance value and the input insomnia degree parameter.

[0023] This technical solution achieves precise adaptation from three dimensions: magnetic induction intensity, magnetic field frequency, and mode switching logic. In static mode, the air gap between the main permanent magnet and the magnetic guide plate directly affects the propagation path and intensity of the magnetic field. By adjusting the size of the air gap through a mechanical structure, continuous changes in magnetic induction intensity can be achieved to meet the needs of different intensities of magnetic stimulation. Compared to a fixed air gap design, this adjustment method is more flexible. In dynamic mode, a stepper motor drives the permanent magnet to rotate around its axis. The periodic rotation of the permanent magnet creates an alternating magnetic field in the central area. The stepper motor's rotation speed is fixedly correlated with the magnetic field frequency. By adjusting the motor speed through the control system, the magnetic field frequency can be continuously adjusted to adapt to different treatment scenarios requiring different frequencies. Adaptive mode switching is the core innovation of this solution. The impedance value of human tissue can reflect the physiological state of the head tissue. Users with different degrees of insomnia have different needs for magnetic stimulation. By collecting these two key parameters, the actual needs of users can be accurately determined, and then the static or dynamic mode can be automatically matched, avoiding the blindness of traditional fixed mode switching. This multi-dimensional adjustment and adaptation mechanism enables the magnetic therapy device to flexibly adjust the stimulation mode and parameters according to the user's individual situation and actual needs, thereby improving the pertinence and adaptability of magnetic stimulation and ensuring that the magnetic field output by the magnetic circuit can better meet the needs of actual applications.

[0024] In the existing technology, the relevant parameters for selecting the operating point of the static magnetic circuit are vaguely defined and lack clear composition and definition, which leads to confusion in the operating point correction logic and insufficient accuracy of the correction results.

[0025] Based on this, in the selection of the operating point of the static magnetic circuit, the characteristic points of the demagnetization curve are the intersection points of the demagnetization curve and the magnetic induction intensity coordinate axis and the intersection points of the demagnetization curve and the magnetic field intensity coordinate axis. The magnetic circuit structure parameters include air gap parameters, main permanent magnet parameters, magnetic flux utilization coefficient and magnetic reluctance coefficient. The air gap parameters include the air gap cross-sectional area and the air gap length. The main permanent magnet parameters include the main permanent magnet cross-sectional area and the main permanent magnet effective length.

[0026] This technical solution provides a clear basis and standardized process for selecting the operating point of a static magnetic circuit by clearly defining and constructing parameters. The characteristic points of the demagnetization curve are crucial for constructing the load line. These are explicitly defined as the intersections of the demagnetization curve with the magnetic induction intensity coordinate axis and the demagnetization curve with the magnetic field intensity coordinate axis. This provides a clear reference benchmark for load line construction, avoiding deviations caused by the ambiguity of traditional characteristic point definitions. Magnetic circuit structural parameters are the core input for correcting the operating point coordinate ratio. They are clearly divided into air gap parameters, main permanent magnet parameters, flux utilization coefficient, and reluctance coefficient. Each category of parameters has a clear purpose. The air gap cross-sectional area and air gap length directly reflect the structural characteristics of the air gap. The main permanent magnet cross-sectional area and effective length reflect the structural dimensions of the main permanent magnet. The flux utilization coefficient reflects the effective utilization of magnetic flux, and the reluctance coefficient characterizes the influence of reluctance in the magnetic circuit. This clear classification and definition makes the acquisition and use of magnetic circuit structural parameters more standardized. The clear definition and classification of all parameters eliminate the ambiguity caused by the vague definition of traditional parameters, making the working point coordinate correction process more systematic. The parameters on which each correction step depends are clear and specific, ensuring that the correction process is quantifiable and repeatable, improving the accuracy and reliability of working point determination, and providing a solid foundation for the efficient design of magnetic circuits.

[0027] In the existing technology, there is a lack of clear specifications for the structural design related to the suppression of self-demagnetization effect, and the methods for magnetic domain stabilization are limited, resulting in poor self-demagnetization suppression effect of the magnetic circuit and insufficient magnetic domain stability of the magnetic core.

[0028] Based on this, the closed magnetic circuit structure is composed of a magnetic core and a magnetic conductive plate. The magnetic conductive plate is made of electrical pure iron. The compensating magnetic ring is nested in the magnetic circuit output end. The magnetic domain stabilization treatment is performed by vacuum annealing the magnetic core. The magnetic circuit output end is on the side facing the human head.

[0029] This technical solution constructs a highly efficient self-demagnetizing suppression system by clearly defining the structural composition, material selection, and processing technology. The closed magnetic circuit structure is key to reducing magnetic leakage. The magnetic core and the magnetic guide plate are spliced ​​together to form a complete magnetic flux loop, guiding the magnetic flux along a preset path and reducing leakage. The magnetic guide plate is made of electrical pure iron, which, due to its excellent magnetic permeability, reduces magnetic resistance in the magnetic circuit, further improving flux utilization and enhancing the leakage suppression effect of the closed magnetic circuit. A compensating magnetic ring is nested at the magnetic circuit output end facing the human head. Its magnetic field direction is opposite to the self-demagnetizing direction of the main permanent magnet. This reverse magnetic field directly cancels out part of the self-demagnetizing effect of the main permanent magnet, achieving self-demagnetizing suppression from the perspective of external magnetic field superposition. Compared to traditional designs without a compensating magnetic ring, this structure significantly improves the self-demagnetizing suppression effect. The magnetic domain stabilization process employs vacuum annealing, which effectively reduces internal stress in the magnetic core. Internal stress is a significant cause of magnetic domain disorder. Vacuum annealing lowers the probability of domain disorder during core operation, improving domain stability at the internal structural level and extending the time before self-demagnetization occurs. These three processes work synergistically to efficiently suppress self-demagnetization from three dimensions: reduced leakage flux, external magnetic field compensation, and internal structural stability, ensuring the long-term stability of the magnetic circuit.

[0030] In existing technologies, the working point coordinate correction only considers one or a few factors, ignoring the influence of complex working conditions such as leakage flux and temperature changes, resulting in insufficient correction accuracy and poor magnetic circuit working stability.

[0031] Based on this, the working point coordinate ratio correction adopts the working point coordinate ratio correction formula. The working point coordinate ratio correction formula is calculated by comprehensively considering the air gap length, the cross-sectional area of ​​the main permanent magnet, the magnetic flux utilization coefficient, the relative permeability of the yoke, the effective length of the main permanent magnet, the cross-sectional area of ​​the air gap, the magnetic reluctance coefficient, the actual working temperature of the magnetic circuit, and the standard working temperature of the magnetic circuit, so as to eliminate the influence of leakage flux and temperature changes on the stability of the working point.

[0032] The working point coordinate ratio correction formula in this technical solution is:

[0033] ;

[0034] Where K is the corrected operating point coordinate ratio, dimensionless, used to accurately characterize the actual operating point position of the main permanent magnet; its value directly reflects the degree of fit between the operating point and the ideal maximum magnetic energy product point; L g S represents the air gap length, measured in meters, and refers to the actual extension length of the air gap in the magnetic circuit. It is one of the key structural parameters affecting the magnetic reluctance of the magnetic circuit. mε is the cross-sectional area of ​​the main permanent magnet, measured in square meters. It specifically refers to the cross-sectional area of ​​the main permanent magnet perpendicular to the direction of magnetic flux propagation and directly relates to the magnetic flux output capability of the main permanent magnet. ε is the magnetic flux utilization coefficient, dimensionless, used to reflect the proportion of magnetic flux effectively utilized in the magnetic circuit. Its value is closely related to the sealing performance of the magnetic circuit structure. μ r L is the relative permeability of the yoke, dimensionless, and is the ratio of the permeability of the yoke material to the permeability of free space, reflecting the magnetic permeability of the yoke; m The effective length of the main permanent magnet, measured in meters, refers to the path length through which magnetic flux can effectively pass in the main permanent magnet, affecting the magnetic field strength output of the main permanent magnet; S g is the cross-sectional area of ​​the air gap, in square meters, which is the cross-sectional area of ​​the air gap perpendicular to the direction of magnetic flux propagation. Together with the air gap length, it determines the magnetic reluctance characteristics of the air gap; f is the magnetic reluctance coefficient, dimensionless, which specifically characterizes the comprehensive influence of various structures in the magnetic circuit on the magnetic flux resistance; T is the actual operating temperature of the magnetic circuit, in Kelvin, which is the real-time temperature of the magnetic circuit during actual operation; T0 is the standard operating temperature of the magnetic circuit, in Kelvin, which is the reference temperature set during the design of the magnetic circuit and is used to measure the deviation between the actual temperature and the ideal operating temperature.

[0035] The theoretical basis of this formula mainly stems from Ohm's law for magnetic circuits and the theory of thermomagnetic effects. Ohm's law states that magnetic flux is directly proportional to magnetomotive force and inversely proportional to magnetic reluctance. Since the operating point coordinate ratio is directly related to the magnetomotive force output of the main permanent magnet, the formula starts with the magnetic circuit structural parameters, quantifying the magnetic reluctance characteristics of the magnetic circuit through air gap parameters, main permanent magnet parameters, magnetic flux utilization coefficient, and magnetic reluctance coefficient, ensuring that the corrected operating point can adapt to the actual magnetic reluctance of the magnetic circuit. The theory of thermomagnetic effects shows that temperature changes affect the magnetic properties of permanent magnet materials and the magnetic permeability of the magnetic circuit, thus affecting the stability of the operating point. Therefore, the formula introduces a temperature-related term, quantifying the impact of temperature changes on the operating point through the ratio of the actual operating temperature to the standard operating temperature.

[0036] The logical derivation process is as follows: First, based on Ohm's law for magnetic circuits, a basic expression for the operating point coordinate ratio is derived, considering only the magnetic circuit structural parameters. This expression includes parameters such as the air gap length, the cross-sectional area of ​​the main permanent magnet, the flux utilization coefficient, the effective length of the main permanent magnet, the air gap cross-sectional area, and the reluctance coefficient, which can reflect the influence of the magnetic circuit structure on the operating point. Second, considering the influence of the magnetic permeability of the yoke on the magnetic reluctance of the magnetic circuit, the relative permeability of the yoke is introduced into the basic expression to further optimize the accuracy of the structural parameters in representing the operating point. Finally, combined with the thermomagnetic effect theory, a temperature correction term is introduced into the denominator of the expression. The interference of temperature changes on the operating point is quantified through the temperature ratio correlation formula under the square root, ultimately forming a complete operating point coordinate ratio correction formula.

[0037] The core innovation of this formula lies in its synergistic correction of multiple factors. Traditional correction formulas often only consider some parameters in the magnetic circuit structure, neglecting the influence of yoke permeability and temperature changes. This formula, however, integrates three major categories of influencing factors: magnetic circuit structure parameters, yoke material properties, and temperature changes. This comprehensively covers the main causes of operating point deviations in actual operating conditions. It precisely quantifies the impact of leakage flux through the flux utilization coefficient and reluctance coefficient, reflects the yoke's optimization effect on the magnetic circuit through the relative permeability of the yoke, and counteracts the interference caused by temperature fluctuations through the temperature correction term. The synergistic effect of these multiple parameters ensures that the operating point remains stable within the ideal range even under complex operating conditions, significantly improving the stability and reliability of the magnetic circuit.

[0038] In existing technologies, self-demagnetizing effect compensation is mostly a fixed compensation method, which lacks quantitative basis, cannot dynamically adapt to changes in the working state of the magnetic circuit, and has poor compensation effect.

[0039] Based on this, the self-demagnetizing effect suppression adopts the self-demagnetizing dynamic compensation coefficient formula, which integrates the cumulative working time of the magnetic therapy device, the magnetic domain attenuation coefficient, the corrected working point coordinate ratio, the inherent stabilization time of the main permanent magnet magnetic domain, the average magnetic permeability of human head tissue, and the vacuum magnetic permeability to achieve dynamic quantitative compensation of the self-demagnetizing effect.

[0040] The formula for the self-demagnetizing dynamic compensation coefficient in this technical solution is:

[0041] ;

[0042] Where δ is the self-demagnetizing dynamic compensation coefficient, dimensionless, used to accurately quantify the actual compensation degree of the self-demagnetizing effect; the closer its value is to 1, the better the self-demagnetizing compensation effect; t is the cumulative working time of the magnetic therapy device, in seconds, referring to the cumulative running time of the magnetic therapy device from startup to the current moment; the longer the cumulative working time, the more obvious the self-demagnetizing effect is usually; k d τ0 is the domain decay coefficient, dimensionless, 1 / second, specifically characterizing the rate at which the magnetic domains of the main permanent magnet decay naturally over time; its value is closely related to the material properties of the main permanent magnet. K is the corrected operating point coordinate ratio, dimensionless, directly derived from the result of the operating point coordinate ratio correction, reflecting the current operating point state of the main permanent magnet. τ0 is the inherent settling time of the main permanent magnet's magnetic domains, dimensionless, representing the reference time for the main permanent magnet's magnetic domains to remain stable without external interference, reflecting the domain stability of the main permanent magnet itself. μ avg is the average permeability of human head tissue, with dimensions in Henry / meter. It is the average permeability of various tissues in the human head, such as skin, fat, muscle, and bone, reflecting the influence of human head tissue on the magnetic field of the magnetic circuit; μ0 is the vacuum permeability, with dimensions in Henry / meter. It is the permeability constant in a vacuum environment and serves as a benchmark for permeability comparison.

[0043] The theoretical design of this formula is mainly based on the domain wall displacement theory and the principle of magnetic circuit magnetic field superposition. The domain wall displacement theory indicates that the self-demagnetization effect of the main permanent magnet is essentially the attenuation of magnetic properties caused by domain structure disorder and domain wall displacement. The domain attenuation rate and cumulative operating time are key factors affecting domain disorder. Therefore, the formula integrates cumulative operating time and domain attenuation coefficient to quantify the self-demagnetization effect caused by natural domain attenuation. The principle of magnetic circuit magnetic field superposition states that an external magnetic field can superimpose with the main permanent magnet's own magnetic field, thus affecting the actual magnetic field output of the main permanent magnet. Human head tissue, as the object of the magnetic circuit magnetic field, has permeability that affects the distribution and intensity of the magnetic field, indirectly affecting the manifestation of the self-demagnetization effect. Therefore, the formula introduces the average permeability and vacuum permeability of human head tissue to characterize the influence of the external magnetic environment on the self-demagnetization effect.

[0044] The logical derivation process is as follows: First, based on the domain wall displacement theory, a quantitative expression for the self-demagnetization effect considering only the natural decay of the domains is derived. This expression includes the cumulative working time, the domain decay coefficient, and the inherent stabilization time of the main permanent magnet domains, which can reflect the degree of influence of the natural decay of the domains on self-demagnetization. Second, considering that the working point state of the main permanent magnet will affect the stability of the domains and thus affect the self-demagnetization effect, a modified working point coordinate ratio is introduced into the expression, and the exacerbation effect of the working point offset on the self-demagnetization effect is quantified by the (1-K) term. Finally, combined with the principle of magnetic circuit magnetic field superposition, the ratio of the average permeability of human head tissue to the vacuum permeability is introduced into the denominator of the expression to characterize the suppression or exacerbation effect of the external magnetic environment on the self-demagnetization effect, and finally a complete formula for the self-demagnetization dynamic compensation coefficient is formed.

[0045] The core innovation of this formula lies in its ability to dynamically quantify and compensate for the self-demagnetizing effect. Traditional compensation methods often rely on fixed structures or parameters, failing to adapt to changes in the magnetic circuit's operating state. This formula, however, integrates four main categories of dynamically changing factors: magnetic circuit operating time, operating point state, the characteristics of the main permanent magnet itself, and the external magnetic environment. This allows for real-time quantification of the actual degree of self-demagnetizing effect, enabling adjustments to the compensation strategy accordingly. By tracking the natural decay process of magnetic domains through accumulated operating time and the domain decay coefficient, correlating the magnetic circuit's operating state through the operating point coordinate ratio, and adapting to changes in the external magnetic environment through the average permeability of human head tissue, dynamic adaptation to self-demagnetizing compensation is achieved, significantly improving the accuracy and effectiveness of self-demagnetizing suppression under different operating conditions.

[0046] Existing technologies for evaluating magnetic energy utilization efficiency often only consider a single parameter or a few factors, failing to fully reflect the synergistic effects of multiple factors such as magnetic circuit structure, operating status, and external environment, resulting in insufficient accuracy of the evaluation results.

[0047] Based on this, the magnetic energy utilization efficiency calculation of the magnetic circuit adopts the magnetic energy utilization efficiency formula. The magnetic energy utilization efficiency formula combines the maximum magnetic energy product of the main permanent magnet, the corrected working point coordinate ratio, the self-demagnetizing dynamic compensation coefficient, the cross-sectional area of ​​the main permanent magnet, the effective length of the main permanent magnet, the vacuum permeability, the air gap magnetic field strength, the air gap cross-sectional area, the air gap length, and the magnetic circuit leakage correction coefficient to achieve an accurate evaluation of the magnetic energy utilization efficiency.

[0048] The formula for magnetic energy utilization efficiency in this technical solution is:

[0049] ;

[0050] Where Ψ is the magnetic energy utilization efficiency, which is dimensionless and is used to comprehensively characterize the effective utilization ratio of the magnetic energy stored in the main permanent magnet in the magnetic circuit. Its value directly reflects the energy utilization level of the magnetic circuit. δ is the maximum magnetic energy product of the main permanent magnet, with dimensions in joules per cubic meter. It is the core indicator of the main permanent magnet material's ability to store and output magnetic energy, reflecting the magnetic energy storage capacity of the main permanent magnet itself; K is the corrected operating point coordinate ratio, dimensionless, reflecting the degree of fit between the current operating point of the main permanent magnet and the maximum magnetic energy product point; δ is the self-demagnetization dynamic compensation coefficient, dimensionless, characterizing the compensation effect of the self-demagnetization effect. The cross-sectional area of ​​the main permanent magnet is measured in square meters. The effective length of the main permanent magnet is measured in meters. and These factors collectively determine the volume of the main permanent magnet and affect its total magnetic energy storage capacity. ν is the vacuum permeability, with dimensions in Henry / meter, and is the reference constant for calculating the magnetic field of a magnetic circuit; The air gap magnetic field strength, with dimensions in Ampere / meter, is a direct representation of the magnetic field strength in the air gap. Its square term is the core parameter for calculating the air gap magnetic energy density. is the cross-sectional area of ​​the air gap, with the dimension of square meters; is the air gap length, in meters; and Together they determine the volume of the air gap and affect the magnetic energy loss of the air gap; is the magnetic leakage correction coefficient, dimensionless, specifically used to correct the influence of magnetic leakage on magnetic energy utilization efficiency; coefficient 1 / 2 is the inherent correction coefficient of magnetic energy density of air gap linear magnetic medium, which is a dimensionless constant.

[0051] The theoretical basis of this formula is mainly the law of conservation of energy and the principle of magnetic circuit power balance. The law of conservation of energy states that energy cannot be created or destroyed; it can only be transformed from one form to another or transferred from one object to another. Magnetic energy in a magnetic circuit is mainly stored in the main permanent magnet, with some loss in the air gap and some leakage due to magnetic flux leakage. Therefore, magnetic energy utilization efficiency is essentially the ratio of effectively utilized magnetic energy to the total stored magnetic energy. The principle of magnetic circuit power balance indicates that the input magnetic power of the magnetic circuit equals the sum of the output magnetic power and the lost magnetic power. Magnetic energy utilization efficiency is directly related to the power balance state of the magnetic circuit. Therefore, the formula needs to integrate various parameters affecting magnetic energy storage, loss, and leakage in the magnetic circuit, and the air gap magnetic energy loss needs to be calculated according to the formula for the magnetic energy density of linear magnetic media. The calculation, combined with the air gap volume, is used to quantify the magnetic energy loss.

[0052] The logical derivation process is as follows: First, based on the magnetic energy storage characteristics of the main permanent magnet, the calculation expression for the total magnetic energy of the main permanent magnet is derived. This expression consists of the maximum magnetic energy product of the main permanent magnet, the operating point coordinate ratio, the self-demagnetization compensation coefficient, and the volume of the main permanent magnet. It can comprehensively reflect the actual magnetic energy storage of the main permanent magnet. Among them, the operating point coordinate ratio corrects the working state of the main permanent magnet, the self-demagnetization compensation coefficient corrects the magnetic energy attenuation caused by the self-demagnetization effect, and the magnetic energy of the main permanent magnet is calculated. Secondly, based on the air gap magnetic energy loss characteristics of linear magnetic media, a calculation expression for air gap magnetic energy loss is derived. This expression includes 1 / 2 times the vacuum permeability, the square term of the air gap magnetic field strength, the air gap volume, and the leakage magnetic field correction coefficient. This expression can accurately quantify the magnetic energy loss in the air gap and the magnetic energy loss caused by leakage magnetic field. Finally, according to the law of conservation of energy, the magnetic energy utilization efficiency is equal to the ratio of the effective output magnetic energy of the main permanent magnet to the total magnetic energy. The effective output magnetic energy of the main permanent magnet is equal to the total magnetic energy minus the magnetic energy lost due to air gap loss and leakage. Based on this, the expressions for the total magnetic energy of the main permanent magnet and the expressions for the magnetic energy loss of the air gap are substituted into the ratio relationship to finally form a complete formula for magnetic energy utilization efficiency.

[0053] The core innovation of this formula lies in its ability to accurately assess magnetic energy utilization efficiency through the synergistic effect of multiple factors. Traditional assessment methods often consider only the characteristics of the main permanent magnet itself or a single structural parameter, neglecting the synergistic influence of multiple factors such as operating point state, self-demagnetization effect, and leakage flux. This formula, however, integrates five key categories of factors: main permanent magnet material properties, operating point state, self-demagnetization compensation effect, magnetic circuit structural parameters, and leakage flux influence, comprehensively covering the main aspects affecting magnetic energy utilization efficiency. It reflects the potential of the main permanent magnet itself through the maximum magnetic energy product, reflects the impact of the actual operating state through the operating point coordinate ratio and self-demagnetization compensation coefficient, quantifies magnetic energy storage and loss through the structural parameters of the main permanent magnet and air gap, and corrects for the impact of magnetic energy leakage through the leakage flux correction coefficient. This synergistic effect of multiple factors ensures that the assessment results accurately and comprehensively reflect the magnetic energy utilization level of the magnetic circuit, providing a precise basis for magnetic circuit optimization design.

[0054] Existing finite element simulation verification technologies often suffer from incomplete model construction, focusing only on the magnetic circuit itself while ignoring the influence of human tissue. Furthermore, the simulation scenarios are limited, failing to comprehensively verify the performance of the magnetic circuit under different operating conditions.

[0055] Based on this, in the finite element simulation verification, the magnetic therapy device model includes a magnetic core, a coil, and a compensating magnetic ring. The magnetic core uses neodymium iron boron permanent magnet material, and the coil is wound with copper wire. The human tissue coupling model includes a layered structure of skin, fat, muscle, and bone. The finite element simulation verification includes stimulation mode simulation, operating point simulation, and self-demagnetization simulation. The stimulation mode simulation verifies the magnetic field distribution under different stimulation modes, the operating point simulation verifies the change in magnetic induction intensity of the magnetic core under different currents, and the self-demagnetization simulation verifies the magnetic field attenuation law with and without compensation.

[0056] This technical solution achieves comprehensive and accurate verification of magnetic circuit performance through the construction of a complete coupling model and multi-scenario simulation. The construction of the magnetic therapy device model fully considers the composition and material properties of the core components. The magnetic core uses neodymium iron boron permanent magnet material, which, due to its excellent magnetic properties, can provide a stable and powerful magnetic field. The coil is wound with copper wire, which has good conductivity, effectively transmitting current and generating an auxiliary magnetic field. The compensating magnetic ring, as a key component for self-demagnetization suppression, is also incorporated into the model, ensuring that the model can realistically reflect the actual structure and performance of the magnetic therapy device. The human tissue coupling model adopts a layered structure of skin, fat, muscle, and bone, conforming to the actual physiological structure of the human head. Different tissues have different permeabilities and conductivities, which directly affect the propagation and distribution of the magnetic field. Coupled with the human tissue coupling model, the magnetic therapy device model can realistically simulate the effect of the magnetic field on the human head, avoiding the problem of traditional simple magnetic circuit simulation being disconnected from actual application scenarios.

[0057] Multi-scenario simulations cover key operating conditions of the magnetic circuit. Stimulation mode simulations are conducted separately for static and dynamic modes to verify the distribution of the magnetic field on the human head under different modes, ensuring that the magnetic field can accurately act on the target area. Operating point simulations verify the effectiveness of the operating point optimization design by simulating the changes in magnetic induction intensity of the magnetic core under different currents, ensuring that the magnetic induction intensity of the magnetic core remains stable within the ideal range. Self-demagnetization simulations verify the effect of self-demagnetization suppression design by comparing the magnetic field attenuation law with and without compensation, ensuring that the magnetic field attenuation is within an acceptable range. These three types of simulations complement each other, comprehensively covering the core performance indicators of the magnetic circuit, enabling timely identification and optimization of design problems, improving the reliability and scientific rigor of the magnetic circuit design, while reducing the number and cost of physical experiments and shortening the R&D cycle.

[0058] In the existing technology, there is a lack of clear standards for the selection of materials for the main permanent magnet and related components, and the structural design is unreasonable, resulting in unstable magnetic circuit performance and poor consistency.

[0059] Based on this, the main permanent magnet is made of N50NdFeB permanent magnet material, the main permanent magnet is processed into permanent magnet blocks, the permanent magnet blocks are evenly distributed along the circumference of the stepper motor shaft, the closed magnetic circuit structure designed with self-demagnetizing effect includes a magnetic yoke, the magnetic yoke is processed into a ring structure, and the compensation magnetic ring is made of SmCo27 samarium cobalt magnetic material.

[0060] This technical solution ensures the performance stability and consistency of the core components of the magnetic circuit through clear material selection and structural design. The main permanent magnet uses N50NdFeB permanent magnet material, which possesses high remanence, high coercivity, and high maximum energy product. This material provides a stable and powerful magnetic field output for the magnetic circuit, meeting the requirements of magnetic therapy devices for magnetic field strength and stability. Compared to ordinary permanent magnet materials, its magnetic properties are superior and its service life is longer. The main permanent magnet is processed into a permanent magnet block shape, which facilitates installation and fixation. Its uniform distribution along the circumference of the stepper motor axis ensures the uniformity of the magnetic field, allowing the magnetic field formed in the central area to stably act on the target area, avoiding magnetic field distortion caused by uneven distribution of the main permanent magnet. The yoke is processed into a ring structure. The ring structure forms a closed magnetic flux loop, guiding the magnetic flux along the yoke, reducing flux leakage, and improving the magnetic flux utilization rate of the magnetic circuit. Simultaneously, the ring structure has good structural stability, providing a stable mounting foundation for the main permanent magnet and other components. The compensating magnetic ring uses SmCo27 samarium cobalt magnetic material, which has good magnetic and temperature stability. Its remanence is opposite to the self-demagnetization direction of the main permanent magnet, effectively counteracting part of the self-demagnetization effect. Compared with other magnetic materials, its magnetic performance decays less during operation, ensuring long-term stability of the self-demagnetization suppression effect. The material selection and structural design of the core components have been precisely considered to ensure that the components can work together to improve the overall performance stability and consistency of the magnetic circuit.

[0061] The existing technology lacks a clear mode switching logic and has a relatively simple control method, which cannot meet the operating habits and actual needs of different users. The convenience and flexibility of the switching process are also insufficient.

[0062] Based on this, the adaptive mode switching includes automatic switching and manual switching. The automatic switching is executed by the microcontroller based on the human tissue impedance value and insomnia level parameters. The microcontroller receives data collected by the magnetic field detection module and the impedance detection module. The magnetic field detection module uses a Hall sensor, and the impedance detection module uses silver electrodes to construct an AC impedance circuit. The manual switching is achieved through the button on the side of the magnetic therapy device.

[0063] This technical solution constructs a flexible and convenient mode switching system by designing both automatic and manual switching modes. The automatic switching mode uses a microcontroller as the control core. Microcontrollers are characterized by high processing speed and high control precision, enabling rapid processing of collected parameters and decision-making. The magnetic field detection module uses a Hall sensor, which has the advantages of high sensitivity and fast response speed, and can accurately collect magnetic field strength data of the magnetic circuit in real time, providing a basis for magnetic field status for mode switching. The impedance detection module uses silver electrodes to construct an AC impedance circuit. Silver electrodes have good conductivity and biocompatibility, and can accurately collect the impedance value of human head tissue. Combined with the input insomnia level parameters, the microcontroller can accurately determine the user's actual needs and then automatically switch to the appropriate stimulation mode, achieving intelligent and precise mode switching. The manual switching mode is achieved through buttons on the side of the magnetic therapy device. The button design is easy for users to operate, allowing them to actively switch modes according to their own feelings, compensating for the lack of flexibility in the automatic switching mode. The two switching modes complement each other: automatic switching ensures precise and intelligent mode selection, while manual switching ensures operational flexibility and convenience. Users can choose the appropriate switching mode according to their own situation and operating habits, improving the user experience and ease of operation of the magnetic therapy device. Simultaneously, the precise data acquisition from the magnetic field detection module and impedance detection module provides a reliable basis for automatic switching, ensuring its accuracy and stability.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A magnetic circuit analysis method for a permanent magnetic field sleep magnetic therapy device, characterized in that, The study includes stimulation mode design, static magnetic circuit operating point selection, self-demagnetization effect guidance design, and finite element simulation verification. The stimulation mode design includes static and dynamic modes. The static mode provides a steady magnetic field, while the dynamic mode provides an alternating magnetic field. The static magnetic circuit operating point selection constructs a load line by using characteristic points of the demagnetization curve. The intersection of the load line and the demagnetization curve is the point of maximum magnetic energy product. The operating point coordinate ratio is corrected by combining the magnetic circuit structure parameters. The self-demagnetization effect guidance design adopts a closed magnetic circuit structure, a compensating magnetic ring installation, and magnetic domain stabilization treatment. The magnetic field direction of the compensating magnetic ring is opposite to the self-demagnetization direction of the main permanent magnet. The finite element simulation verification constructs a coupling model between the magnetic therapy device and human tissue.

2. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 1, characterized in that, The static mode achieves continuous variation of magnetic induction intensity by adjusting the air gap between the main permanent magnet and the magnetic plate. The dynamic mode generates a low-frequency alternating magnetic field by driving a permanent magnet block to rotate around an axis using a stepper motor. The speed of the stepper motor is adjusted by a control system to achieve continuous adjustment of the alternating magnetic field frequency. The stimulation mode design also includes adaptive mode switching, which determines the target stimulation mode based on the collected human tissue impedance value and the input insomnia level parameters.

3. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 1, characterized in that, In the selection of the operating point of the static magnetic circuit, the characteristic points of the demagnetization curve are the intersection points of the demagnetization curve and the magnetic induction intensity coordinate axis and the intersection points of the demagnetization curve and the magnetic field intensity coordinate axis. The magnetic circuit structure parameters include air gap parameters, main permanent magnet parameters, magnetic flux utilization coefficient and magnetic reluctance coefficient. The air gap parameters include the air gap cross-sectional area and the air gap length. The main permanent magnet parameters include the main permanent magnet cross-sectional area and the main permanent magnet effective length.

4. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 1, characterized in that, The closed magnetic circuit structure is composed of a magnetic core and a magnetic guide plate. The magnetic guide plate is made of electrical pure iron. The compensating magnetic ring is nested in the magnetic circuit output end. The magnetic domain stabilization treatment uses a vacuum annealing process to treat the magnetic core. The magnetic circuit output end is on the side facing the human head.

5. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 3, characterized in that, The working point coordinate ratio correction adopts the working point coordinate ratio correction formula, which is calculated by comprehensively considering the air gap length, the cross-sectional area of ​​the main permanent magnet, the magnetic flux utilization coefficient, the relative permeability of the yoke, the effective length of the main permanent magnet, the cross-sectional area of ​​the air gap, the magnetic reluctance coefficient, the actual working temperature of the magnetic circuit, and the standard working temperature of the magnetic circuit, so as to eliminate the influence of leakage flux and temperature changes on the stability of the working point.

6. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 4, characterized in that, The self-demagnetizing effect is suppressed by using a self-demagnetizing dynamic compensation coefficient formula. This formula integrates the cumulative working time of the magnetic therapy device, the magnetic domain attenuation coefficient, the corrected working point coordinate ratio, the inherent stabilization time of the main permanent magnet magnetic domain, the average permeability of human head tissue, and the vacuum permeability to achieve dynamic quantitative compensation for the self-demagnetizing effect.

7. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 5, characterized in that, The magnetic energy utilization efficiency calculation adopts the magnetic energy utilization efficiency formula, which combines the maximum magnetic energy product of the main permanent magnet, the corrected working point coordinate ratio, the self-demagnetizing dynamic compensation coefficient, the cross-sectional area of ​​the main permanent magnet, the effective length of the main permanent magnet, the vacuum permeability, the air gap magnetic field strength, the air gap cross-sectional area, the air gap length, and the magnetic circuit leakage correction coefficient to achieve an accurate assessment of the magnetic energy utilization efficiency.

8. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 1, characterized in that, In the finite element simulation verification, the magnetic therapy device model includes a magnetic core, a coil, and a compensating magnetic ring. The magnetic core uses neodymium iron boron permanent magnet material, and the coil is wound with copper wire. The human tissue coupling model includes a layered structure of skin, fat, muscle, and bone. The finite element simulation verification includes stimulation mode simulation, operating point simulation, and self-demagnetization simulation. The stimulation mode simulation verifies the magnetic field distribution under different stimulation modes, the operating point simulation verifies the change in magnetic induction intensity of the magnetic core under different currents, and the self-demagnetization simulation verifies the magnetic field attenuation law with and without compensation.

9. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 1, characterized in that, The main permanent magnet is made of N50NdFeB permanent magnet material. The main permanent magnet is processed into permanent magnet blocks. The permanent magnet blocks are evenly distributed along the circumference of the stepper motor shaft. The closed magnetic circuit structure designed with self-demagnetizing effect includes a magnetic yoke. The magnetic yoke is processed into a ring structure. The compensation magnetic ring is made of SmCo27 samarium cobalt magnetic material.

10. The magnetic circuit analysis method for the permanent magnetic field sleep magnetic therapy device according to claim 2, characterized in that, The adaptive mode switching includes automatic switching and manual switching. The automatic switching is executed by the microcontroller based on the human tissue impedance value and insomnia level parameters. The microcontroller receives data collected by the magnetic field detection module and the impedance detection module. The magnetic field detection module uses a Hall sensor, and the impedance detection module uses silver electrodes to construct an AC impedance circuit. The manual switching is achieved through the button on the side of the magnetic therapy device.

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