CN113933599B - Magnetic core loss determination method and device for current cut-off distortion of integrated circuit - Google Patents

Abstract

A method and apparatus for determining core loss for integrated circuit current cutoff distortion may include: a current having a cut-off distortion waveform is applied to a magnetic core of an inductance component for an integrated circuit power supply system, wherein the current is periodically changed. Under the action of the current, a plurality of characteristic points of a magnetic hysteresis loop of the magnetic core are acquired, wherein the magnetic hysteresis loop represents the change relation between the intensity of the magnetic field acting on the magnetic core and the intensity of magnetic induction generated by the magnetic core. And determining parameters for fitting an S-curve of the hysteresis loop according to the plurality of characteristic points to obtain an equation of the hysteresis loop. The hysteresis loop is integrated according to the equation for the hysteresis loop and based on the definition of the core loss to determine the average power loss of the core. The problem that magnetic core loss is difficult to accurately obtain in the prior art under the condition of direct current bias is avoided, and a convenient and accurate mode is provided for determining the magnetic core loss of the inductance element.

Description

Magnetic core loss determination method and device for current cut-off distortion of integrated circuit

Technical Field

The present disclosure relates to the field of integrated circuit technologies, and in particular, to a method and an apparatus for determining magnetic core loss for current cut-off distortion of an integrated circuit.

Background

The core loss of the inductive element of the system-level integrated circuit power system has a nonlinear characteristic, so that the calculation process is difficult, and a more accurate core loss value is difficult to obtain. Traditionally, the core loss of an inductive element is estimated using the Steinmetz equation, i.e.

Wherein

Is the average power loss per unit time in unit volume of the magnetic core, k, alpha and beta are coefficients related to the magnetic core material, f is the transformer operating frequency under sinusoidal excitation, B_maxThe maximum flux density at which the transformer core operates under sinusoidal excitation. However, the Steinmetz equation is only applicable to sinusoidal excitation, and the waveform of the excitation current passing through the magnetic core of the inductance component of the system-level integrated circuit power supply system is not a sine wave, so that if the Steinmetz equation is used for estimating the core loss value, a large error is inevitably generated, and in addition, the power loss of the magnetic core is also greatly influenced by the direct current bias.

Considering that the loss caused by the motion of the domain wall in the magnetic core of the inductive element is directly related to the rate of change of the magnetic field with time, the Steinmetz equation is improved to a generalized Steinmetz equation, i.e. the equation of Steinmetz

Where T is the period of the excitation current waveform,. DELTA.B is the peak value of the magnetic flux density, and k_iα and β are coefficients related to the core material. In fact k_iAlpha and beta are changesHowever, the generalized Steinmetz formula does relate to k_iα, and β are treated as constants so that there is a large error in using the generalized Steinmetz equation under DC bias conditions. Specifically, FIG. 2 is a triangular waveform schematic of the excitation current through the core with amplifier turn-off distortion, k in the generalized Steinmetz equation at different DC offsets of the triangular waveform current_iAlpha, and beta are also different. As shown in fig. 2, in the period from 0 to rT, the magnetic flux density generated by the inductor of the core and the current satisfy the following relationship:

wherein r is a proportionality coefficient of less than 1, mu₀For vacuum permeability, N is the number of turns of a coil wound on a core for making an inductive component of an integrated circuit power system, I (t) is the operating waveform of the current applied to the inductive component of the integrated circuit power system, l_iFor winding on the ith segment of magnetic core to form the length of the ith segment of inductive element, mu_r,iIs the relative permeability of the ith segment of the core. Therefore, in the period from 0 to rT, the rate of change with time of the magnetic field due to the movement of the domain wall in the magnetic core of the inductance element is 0, that is, the integral in this period is 0, that is, there is no energy loss in this period according to the above formula. However, in practice, during the 0 to rT period, some residual loss may result due to relaxation phenomena. In summary, in the case of the current signal cut-off distortion and the dc offset, the calculation of the core loss using the generalized Steinmetz equation is still inaccurate.

Disclosure of Invention

The present application provides a core loss determination method and apparatus for current cutoff distortion in an integrated circuit that addresses or partially addresses at least one of the above-identified problems related to the background art and other deficiencies in the art.

The application provides a magnetic core loss determination method for current cut-off distortion of an integrated circuit, which comprises the following steps: a current having a cut-off distortion waveform is applied to a magnetic core of an inductance component for an integrated circuit power supply system, wherein the current is periodically changed. Under the action of the current, a plurality of characteristic points of a magnetic hysteresis loop of the magnetic core are acquired, wherein the magnetic hysteresis loop represents the change relation between the intensity of the magnetic field acting on the magnetic core and the intensity of magnetic induction generated by the magnetic core. And determining parameters for fitting an S-curve of the hysteresis loop according to the plurality of characteristic points to obtain an equation of the hysteresis loop. According to the equation of the magnetic hysteresis loop and based on the definition of the magnetic core loss, integrating the magnetic hysteresis loop to determine the average power loss of the magnetic core, wherein the calculation formula of the magnetic core loss is as follows:

wherein H_1minThe magnetic field strength, H, corresponding to the time at which the current reaches the beginning of the cut-off current in the cycle_2minThe magnetic field strength, H, corresponding to the end of the current-to-off period_maxThe magnetic field strength corresponding to the peak of the current, B₁(H) Is the magnetic induction corresponding to the demagnetization curve when the magnetic field strength H changes within the corresponding integration interval, B₂(H) Is the magnetic induction corresponding to the magnetization curve when the magnetic field strength H varies within the corresponding integration interval.

In some embodiments, acquiring multiple characteristic points of the hysteresis loop of the magnetic core under the action of the current may include: in a plurality of periods of the current, a first measuring point, a second measuring point, a third measuring point, a fourth measuring point, a fifth measuring point, a sixth measuring point and a seventh measuring point which are used for preliminarily characterizing the hysteresis loop of the magnetic core are respectively and sequentially acquired. And respectively carrying out averaging processing on the plurality of first measurement points, the plurality of second measurement points, the plurality of third measurement points, the plurality of fourth measurement points, the plurality of fifth measurement points, the plurality of sixth measurement points and the plurality of seventh measurement points to obtain a first characteristic point, a second characteristic point, a third characteristic point, a fourth characteristic point, a fifth characteristic point, a sixth characteristic point and a seventh characteristic point which are used for stably characterizing the hysteresis loop of the magnetic core.

In some embodiments, the characteristic point is a set of pairs having correspondence relationship between a magnetic field intensity value applied to the magnetic core and a magnetic induction intensity value generated by the magnetic core, wherein the characteristic point may include: a first characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value when the magnetic induction intensity value generated by the magnetic core in the magnetization process reaches reverse saturation, and a reverse magnetic induction intensity saturation value of the magnetic core in the magnetization process; a second characteristic point consisting of a value of zero and a residual magnetic induction strength value of the magnetic core in the magnetization process; a third characteristic point consisting of a coercive force value of the material of the magnetic core in the magnetization process and a numerical value of zero; a fourth characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic induction intensity value reaches the forward saturation and the forward magnetic induction intensity saturation value of the magnetic core; a fifth characteristic point consisting of a value zero and a residual magnetic induction intensity value of the magnetic core in the demagnetization process; a sixth characteristic point which consists of the coercive force value of the material of the magnetic core in the demagnetization process and the numerical value of zero; and a seventh characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value when the magnetic induction intensity value generated by the magnetic core reaches reverse saturation in the demagnetization process, and a reverse magnetic induction intensity saturation value of the magnetic core in the demagnetization process.

In some embodiments, determining a parameter for fitting an S-curve of a hysteresis loop to obtain an equation of the hysteresis loop based on the plurality of feature points may include: according to the attribute that the output result converges to a fixed value when the variable of the S curve tends to infinity, setting the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the magnetizing process reaching reverse saturation and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the demagnetizing process reaching reverse saturation as minus infinity, and setting the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core reaching forward saturation as plus infinity; respectively substituting the first characteristic point, the second characteristic point, the third characteristic point and the fourth characteristic point into the S curve to determine an initial value of a parameter of the S curve corresponding to the magnetization process; determining the accurate value of the parameter of the S curve corresponding to the magnetization process by adopting a Newton iteration method so as to determine the magnetization curve equation of the magnetic core; respectively substituting the fourth characteristic point, the fifth characteristic point, the sixth characteristic point and the seventh characteristic point into the S curve to determine an initial value of a parameter of the S curve corresponding to the demagnetization process; determining the accurate value of the parameter of the S curve corresponding to the demagnetization process by adopting a Newton iteration method so as to determine the demagnetization curve equation of the magnetic core; and integrating the magnetization curve equation and the demagnetization curve equation to obtain a magnetic hysteresis loop of the magnetic core.

In some embodiments, the newton's iterative method comprises: determining each parameter of the S curve as an iteration variable; determining a newton iteration formula from the iteration variable, wherein the newton iteration formula represents a formula for deriving a next value of the iteration variable from a previous value of the iteration variable; determining a target function of the iteration variable, and taking the value of the iteration variable corresponding to the module value as an accurate value of the parameter of the S curve in response to the condition that the module value of the target function is smaller than a preset threshold value; wherein the objective function characterizes a difference between a calculated value at a feature point position obtained using an S-curve with an iteration variable as a parameter and a measured value at the feature point position.

In some embodiments, the core loss calculation is formulated as:

wherein, the first and the second end of the pipe are connected with each other,

the average power loss of the magnetic core in unit volume and unit time is shown as f, the waveform frequency of the current is shown as L, the integral path of the integral along the hysteresis loop is shown as L, the magnetic induction intensity generated by the magnetic core is shown as B, and the magnetic field intensity is shown as H.

The present application further provides a core loss determination apparatus for integrated circuit current cutoff distortion, which may include: the device comprises a current supply module, an acquisition module, a fitting module and a loss determination module. The current supply module applies a current having a cut-off distortion waveform to a magnetic core of an inductance element for an integrated circuit power supply system, wherein the current is periodically changed. The acquisition module acquires a plurality of characteristic points of a magnetic hysteresis loop of the magnetic core under the action of current, wherein the magnetic hysteresis loop represents the change relation between the magnetic field intensity acting on the magnetic core and the magnetic induction intensity generated by the magnetic core. And the fitting module determines parameters of an S curve for fitting the hysteresis loop according to the plurality of characteristic points so as to obtain an equation of the hysteresis loop. The loss determination module is used for integrating the hysteresis loop according to an equation of the hysteresis loop and based on the definition of the magnetic core loss to determine the average power loss of the magnetic core, and the calculation formula of the magnetic core loss is as follows:

wherein H_1minThe magnetic field strength, H, corresponding to the time at which the current reaches the beginning of the cut-off current in the cycle_2minThe magnetic field strength, H, corresponding to the end of the current-to-off period_maxThe magnetic field strength corresponding to the peak of the current, B₁(H) Is the magnetic induction corresponding to the demagnetization curve when the magnetic field strength H changes within the corresponding integration interval, B₂(H) Is the magnetic induction corresponding to the magnetization curve when the magnetic field strength H varies within the corresponding integration interval.

In some embodiments, the step of executing the acquisition module may comprise: in a plurality of periods of current, a first measuring point, a second measuring point, a third measuring point, a fourth measuring point, a fifth measuring point, a sixth measuring point and a seventh measuring point which are used for preliminarily characterizing a hysteresis loop of a magnetic core are respectively and sequentially collected; and performing averaging processing on the plurality of first measurement points, the plurality of second measurement points, the plurality of third measurement points, the plurality of fourth measurement points, the plurality of fifth measurement points, the plurality of sixth measurement points and the plurality of seventh measurement points respectively to obtain a first characteristic point, a second characteristic point, a third characteristic point, a fourth characteristic point, a fifth characteristic point, a sixth characteristic point and a seventh characteristic point, which are used for stably characterizing the hysteresis loop of the magnetic core.

In some embodiments, the characteristic point is a set of pairs having a correspondence relationship between a magnetic field intensity value applied to the magnetic core and a magnetic induction intensity value generated by the magnetic core, wherein the characteristic point includes: a first characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value when the magnetic induction intensity value generated by the magnetic core in the magnetization process reaches reverse saturation, and a reverse magnetic induction intensity saturation value of the magnetic core in the magnetization process; the second characteristic point is composed of a value zero and a residual magnetic induction intensity value of the magnetic core in the magnetization process; a third characteristic point consisting of a coercive force value of the material of the magnetic core in the magnetization process and a numerical value of zero; a fourth characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic induction intensity value reaches the forward saturation and the forward magnetic induction intensity saturation value of the magnetic core; a fifth characteristic point consisting of a value zero and a residual magnetic induction intensity value of the magnetic core in the demagnetization process; a sixth characteristic point which consists of the coercive force value of the material of the magnetic core in the demagnetization process and the numerical value of zero; and a seventh characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value when the magnetic induction intensity value generated by the magnetic core reaches reverse saturation in the demagnetization process, and a reverse magnetic induction intensity saturation value of the magnetic core in the demagnetization process.

In some embodiments, the performing of the fitting module may include: according to the attribute that the output result converges to a fixed value when the variable of the S curve tends to infinity, the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the magnetization process reaching reverse saturation and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the demagnetization process reaching reverse saturation are both set to be negative infinity, and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core reaching forward saturation is set to be positive infinity. And respectively substituting the first characteristic point, the second characteristic point, the third characteristic point and the fourth characteristic point into the S curve to determine the initial value of the parameter of the S curve corresponding to the magnetization process. And determining the accurate value of the parameter of the S curve corresponding to the magnetization process by adopting a Newton iteration method so as to determine the magnetization curve equation of the magnetic core. And respectively substituting the fourth characteristic point, the fifth characteristic point, the sixth characteristic point and the seventh characteristic point into the S curve to determine the initial value of the parameter of the S curve corresponding to the demagnetization process. And determining the accurate value of the parameter of the S curve corresponding to the demagnetization process by adopting a Newton iteration method so as to determine the demagnetization curve equation of the magnetic core. And integrating the magnetization curve equation and the demagnetization curve equation to obtain a magnetic hysteresis loop of the magnetic core.

In some embodiments, the newton's iterative method comprises: and respectively determining each parameter of the S curve as an iteration variable. From the iteration variable, a newton iteration formula is determined, where the newton iteration formula represents a formula for deriving a next value of the iteration variable from a previous value of the iteration variable. Determining a target function of the iteration variable, and taking a value of the iteration variable corresponding to the module value as an accurate value of a parameter of the S curve in response to the condition that the module value of the target function is smaller than a preset threshold value; wherein the objective function characterizes a difference between a calculated value at a position of the feature point obtained using an S-curve with an iteration variable as a parameter and a measured value at the position of the feature point.

In some embodiments, the core loss calculation is formulated as:

wherein the content of the first and second substances,

the average power loss of the magnetic core in unit volume and unit time is shown as f, the waveform frequency of the current is shown as L, the integral path of the integral along the hysteresis loop is shown as L, the magnetic induction intensity generated by the magnetic core is shown as B, and the magnetic field intensity is shown as H.

According to the method and the device for determining the magnetic core loss aiming at the current cut-off distortion of the integrated circuit, a plurality of characteristic points of the magnetic core of the inductance element in the integrated power supply circuit system are collected, and then parameters of an S curve used for fitting a magnetic core hysteresis loop are determined through the characteristic points so as to fit the hysteresis loop of the magnetic core, and finally, the magnetic core loss of the inductance element can be obtained through a method of integrating the hysteresis loop directly according to the definition of the magnetic core loss. Based on the above, the problem that the magnetic core loss is difficult to accurately obtain under the condition of direct current bias in the prior art can be solved, and a convenient and accurate mode is provided for determining the magnetic core loss of the inductance element.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings in which:

FIG. 1 is a flow chart of a core loss determination method for integrated circuit current cutoff distortion according to an exemplary embodiment of the present application;

FIG. 2 is a triangular waveform schematic of an excitation current through a magnetic core with input current waveform cutoff distortion;

FIG. 3 is a hysteresis loop diagram corresponding to the current waveform shown in FIG. 2 for a core loss determination method for integrated circuit current turn-off distortion according to an exemplary embodiment of the present application;

FIG. 4 is a hysteresis loop diagram corresponding to the integrated circuit current actual cutoff distortion current shown in FIG. 2 for a core loss determination method for integrated circuit current cutoff distortion according to an exemplary embodiment of the present application when the current is slowly increasing; and

fig. 5 is a schematic structural diagram of a core loss determination apparatus for integrated circuit current cutoff distortion according to an exemplary embodiment of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

In the drawings, the size, dimension, and shape of elements have been slightly adjusted for convenience of explanation. The figures are purely diagrammatic and not drawn to scale. As used herein, the terms "approximately", "about" and the like are used as table-approximating terms and not as table-degree terms, and are intended to account for inherent deviations in measured or calculated values that would be recognized by one of ordinary skill in the art. In addition, in the present application, the order in which the processes of the respective steps are described does not necessarily indicate an order in which the processes occur in actual operation, unless explicitly defined otherwise or can be inferred from the context.

It will be further understood that terms such as "comprising," "including," "having," "including," and/or "containing," when used in this specification, are open-ended and not closed-ended, and specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when a statement such as "at least one of" appears after a list of listed features, it modifies that entire list of features rather than just individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including engineering and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In addition, the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

Fig. 1 is a flow chart of a core loss determination method for integrated circuit current cutoff distortion according to an exemplary embodiment of the present application.

As shown in fig. 1, the present application provides a core loss determination method for integrated circuit current cutoff distortion, which may include: step S1, a current having an off-distortion waveform is applied to a core of an inductance component for an integrated circuit power supply system, wherein the current is periodically changed. And step S2, under the action of the current, acquiring a plurality of characteristic points of a magnetic hysteresis loop of the magnetic core, wherein the magnetic hysteresis loop represents the change relation between the magnetic field intensity acting on the magnetic core and the magnetic induction intensity generated by the magnetic core. In step S3, parameters of an S-curve for fitting the hysteresis loop are determined according to the plurality of feature points to obtain an equation of the hysteresis loop. Step S4, integrating the hysteresis loop according to the equation of the hysteresis loop and based on the definition of the core loss to determine the average power loss of the core.

In some embodiments, first, a current having a cut-off distortion waveform is applied to a magnetic core of an inductance element for an integrated circuit power supply system, that is, a current having a cut-off distortion waveform is applied to a magnetic core. It should be noted that the variation of the current applied to the magnetic core may have periodicity, and the operating waveform of the current may be a sine wave, a triangle wave, or the like, but such a current waveform is cut off and distorted, that is, in order to simulate a phenomenon that a bias current applied to a transistor of an integrated circuit is too small, and a trough of a signal voltage and a trough of the current are flattened, so that the current applied to the magnetic core is cut off and distorted. The magnetic field intensity value applied to the magnetic core is generated by a current applied to the inductance element for the integrated circuit power supply system, and the waveform of the current is completely the same as the operating waveform of the inductance element for the integrated circuit power supply system. Furthermore, in many power supply systems of integrated circuits, magnetic elements need to be pre-magnetized and biased by direct current or low frequency according to the requirements of transistors in the integrated circuits, for example, in the switching power supply circuits of the integrated circuits, magnetic elements operating under direct current bias conditions are generally used, so that the input current signals also have direct current bias conditions, and the problem of cut-off distortion may occur due to too small direct current bias. Based on this, it is first necessary to determine the hysteresis loop of the core of the inductance element according to the operating waveform of the current, and then determine the core loss of the inductance element by an integration method according to the hysteresis loop.

Further, when the current is applied to the magnetic core of the inductance element, a magnetic field varying with the current is generated in the magnetic core under the action of the current, and thus a certain magnetic core loss is generated. Based on the core loss of the core, a corresponding hysteresis loop may be generated. Of course, different current signals through the core will produce hysteresis loops in different states.

FIG. 2 is a triangular waveform schematic of an excitation current through a magnetic core with input current waveform cutoff distortion; and fig. 3 is a hysteresis loop diagram corresponding to the current waveform shown in fig. 2 of a core loss determination method for integrated circuit current cutoff distortion according to an exemplary embodiment of the present application.

In some embodiments, as shown in fig. 2, in order to simulate the phenomenon that the bias current applied to the transistor of the integrated circuit is too small, which results in the valley of the signal voltage and current being flattened, the current waveform applied to the core is triangular and is cut-off distorted, and has a duty cycle T, during which the maximum value of the current is i_maxThe minimum value of the current in the period is i_minAnd the difference between the maximum value and the minimum value of the current in the period is delta i_L. Further, i_DCFor the average current value of the input current, it can be seen that the average current value is larger than zero, in other words, the current signal has a phenomenon of dc offset. In addition, in the operating waveform of the current, the current signal remains unchanged in the time period 0 to rT, and the current value of the time period is the off current, in other words, the current signal at this time has the off distortion. Further, during the period of time when the current is constant, the magnetic field applied to the core is constant, but the magnetization of the core is still proceeding, so that a loss of residual energy still occurs. This is reflected in the hysteresis loop, which, as can be seen in fig. 3, forms a vertical magnetization curve L₁To L₂Segment, L₁To L₂The segment corresponds to the current operation waveform of the time period 0 to rT. At L₁To L₂In the section, the magnetic field intensity H is unchanged, but the magnetic induction B reversely rises; after the time rT, L of the corresponding magnetization curve₂At the point, the current value begins to increase, and the magnetic field intensity H rises along with the rise of the magnetic induction B until the magnetic field intensity H rises to the highest point L₃At this time, the magnetic induction B reaches the maximum in the positive direction; then the current is gradually reduced until the current reaches the minimum value, at the moment, the magnetic induction intensity B value is reduced along with the reduction of the magnetic induction intensity H until the current reaches the cut-off position L₁. It can be seen that the special points of the hysteresis loop may include: l is₁To L₂End points of segments, i.e. L₁Magnetic field intensity H of_minAnd magnetic induction B_1minAnd L₂Magnetic field intensity H of_minAnd magnetic induction B_2min；L₃At a position, i.e. at a magnetic field strength H corresponding to the time of maximum magnetic induction_maxAnd magnetic induction B_max(ii) a Magnetic induction B corresponding to zero magnetic field intensity in magnetization process_r2At least one of (1) and (b); magnetic field intensity H corresponding to magnetic induction intensity being zero in magnetization process_c2At least one of (1) and (b); magnetic induction B corresponding to zero magnetic field strength in demagnetization process_r1At least one of (1) and (b); and the corresponding magnetic field intensity H when the magnetic induction intensity is zero in the demagnetization process_c1To (3).

However, in the actual working environment, the off-distortion current applied to the core is not constant, but the current is still slowly increased from the beginning of the off-distortion to the end of the off-distortion, and the reverse current applied at the end of the off-distortion is maximized, and the hysteresis loop corresponding to the hysteresis loop is shown in fig. 4, which is different from fig. 3 in that the hysteresis loop corresponds to the hysteresis loop

The section is not a vertical line with constant external reverse magnetic field intensity, but the external reverse magnetic field intensity H corresponding to the first characteristic point_2minThe external reverse magnetic field intensity H which is larger than the corresponding seventh characteristic point_1min。

In some embodiments, the S-curve has a characteristic of being steep in the middle, gentle at both ends, and converging to a fixed value, respectively, and the hysteresis loop of the magnetic core includes a magnetization curve and a demagnetization curve each having the same characteristics as the S-curve. Based on this, this application uses S curve to fit magnetization curve and demagnetization curve respectively, and then can constitute the hysteresis loop of magnetic core.

In some embodiments, under the action of the current, a plurality of characteristic points of a hysteresis loop of the magnetic core are acquired, wherein the hysteresis loop represents the variation relation between the intensity of the magnetic field acting on the magnetic core and the intensity of the magnetic induction generated by the magnetic core. Specifically, under the effect of the current, the acquiring of multiple characteristic points of the hysteresis loop of the magnetic core may include: in a plurality of current periods, sequentially collecting a first measuring point, a second measuring point, a third measuring point, a fourth measuring point, a fifth measuring point, a sixth measuring point and a seventh measuring point which are used for preliminarily characterizing a hysteresis loop of the magnetic core; and performing averaging processing on the plurality of first measurement points, the plurality of second measurement points, the plurality of third measurement points, the plurality of fourth measurement points, the plurality of fifth measurement points, the plurality of sixth measurement points and the plurality of seventh measurement points respectively to obtain a first characteristic point, a second characteristic point, a third characteristic point, a fourth characteristic point, a fifth characteristic point, a sixth characteristic point and a seventh characteristic point which are used for stably characterizing the hysteresis loop of the magnetic core. In some embodiments, the characteristic point is a set of pairs having a correspondence relationship between a magnetic field intensity value applied to the magnetic core and a magnetic induction intensity value generated by the magnetic core. The feature points may include: and the first characteristic point is composed of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core in the magnetization process when the magnetic induction intensity value reaches reverse saturation and a reverse magnetic induction intensity saturation value of the magnetic core in the magnetization process. And the second characteristic point consists of a value zero and a residual magnetic induction intensity value of the magnetic core in the magnetization process, wherein the value zero is an external magnetic field intensity value in the magnetization process, and the residual magnetic induction intensity value is the corresponding magnetic induction intensity value of the magnetic core when the external magnetic field intensity value is zero in the magnetization process. And a third characteristic point consisting of a coercive force value of the material of the magnetic core in the magnetization process and a numerical value zero, wherein the coercive force value is an external magnetic field strength value which enables the magnetic induction strength value of the magnetic core to be zero in the magnetization process, and the numerical value zero is the magnetic induction strength value of the magnetic core corresponding to the coercive force value of the material of the magnetic core in the magnetization process. And a fourth characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic induction intensity value reaches the forward saturation value and the forward magnetic induction intensity saturation value of the magnetic core. And a fifth characteristic point consisting of a value zero and a residual magnetic induction intensity value of the magnetic core in the demagnetization process, wherein the value zero is the external magnetic field intensity value in the demagnetization process, and the residual magnetic induction intensity value is the corresponding magnetic induction intensity value of the magnetic core when the external magnetic field intensity value is zero in the demagnetization process. And the sixth characteristic point consists of a coercive force value of the material of the magnetic core in the demagnetization process and a numerical value zero, wherein the coercive force value is an external magnetic field strength value which enables the magnetic induction strength value of the magnetic core to be zero in the demagnetization process, and the numerical value zero is the magnetic induction strength value of the magnetic core corresponding to the coercive force value of the material of the magnetic core in the demagnetization process. And a seventh characteristic point consisting of a magnetic field strength value corresponding to a point at which the magnetic flux density value generated by the magnetic core during demagnetization reaches reverse saturation, and a reverse magnetic flux density saturation value of the magnetic core during demagnetization. Note that, although the saturation magnetic induction values of the cores of the inductance elements made of different materials are different, the saturation magnetic induction values of the cores made of the same material are the same. In other words, the saturation induction value of the magnetic core is determined by the material of the magnetic core. In addition, the coercive force values of the magnetic cores made of the same material are also the same, namely the coercive force is the demagnetizing field strength required when the magnetic induction intensity generated by the magnetic cores is zero; and when the magnetic field intensity is zero, the residual magnetic induction intensity in the magnetic cores made of the same material is the same.

Further, the S-curve may be represented as:

in formula (1), a, b, c, and d each represent a parameter defining an S-curve, e is a natural constant, x represents a variable, and y represents an output result of the S-curve as a function of x.

According to the attribute that the output result y converges to a fixed value when the variable x of the S curve tends to infinity, the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the magnetizing process reaching reverse saturation and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the demagnetizing process reaching reverse saturation are both set to be negative infinity, and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core reaching forward saturation is set to be positive infinity. Further, the first characteristic point, the second characteristic point, the third characteristic point and the fourth characteristic point are respectively substituted into the S curve to determine the initial value of the parameter of the S curve corresponding to the magnetization process. And determining the accurate value of the parameter of the S curve corresponding to the magnetization process by adopting a Newton iteration method so as to determine the magnetization curve equation of the magnetic core. And respectively substituting the fourth characteristic point, the fifth characteristic point, the sixth characteristic point and the seventh characteristic point into the S curve to determine the initial value of the parameter of the S curve corresponding to the demagnetization process. And determining the accurate value of the parameter of the S curve corresponding to the demagnetization process by adopting a Newton iteration method so as to determine the demagnetization curve equation of the magnetic core. And integrating the magnetization curve equation and the demagnetization curve equation to obtain a magnetic hysteresis loop of the magnetic core.

Specifically, the respective parameters a, b, c, and d of the S-curve are respectively determined as iteration variables. From the iteration variable, a newton iteration formula is determined, where the newton iteration formula represents a formula for deriving a next value of the iteration variable from a previous value of the iteration variable. The newton iterative formula can be expressed as:

P⁽ⁱ⁺¹⁾＝P⁽ⁱ⁾-(F′(P⁽ⁱ⁾))^-1F(P⁽ⁱ⁾)， (2)

in formula (2), P is an iteration vector, i is a natural number, and P⁽ⁱ⁾And representing the result of the ith iteration of the variable, wherein F is an objective function, and F' is a Jacobian matrix of the objective function.

The target function is the difference value between the value of the S curve at the characteristic point position and the measured value, which is calculated by reversing the parameter of the S curve determined by the iterative method, and the smaller the difference value is, the closer the parameter of the S curve determined by the iterative method is to the true value of the measurement at the characteristic point. The objective function can be expressed as:

in the formula (3), f_iExpressing a sub-objective function, wherein i is a natural number, specifically, the difference between the value of the position of the ith characteristic point of an S curve taking an iteration vector as a parameter and the measured value of the position of the characteristic point; v. of_calThe value of the S curve at the position of the characteristic point is calculated in reverse according to the parameters of the S curve determined by an iterative method; v. of_meaIs a measurement at the location of the feature point; q is a natural number and represents an acceleration factor of the constructed objective function in the iteration process; n is the number of sub-targeting functions, or the number of feature points.

The Jacobian matrix of the objective function can be expressed as:

in the formula (4), the first and second groups,

the l sub-objective function F representing the objective function F_lFor m variable P of iteration variable P_mAnd (5) calculating partial derivatives, wherein l, m and n are natural numbers.

Set the modulus of the objective function | | | F (P)⁽ⁱ⁾) The threshold value of | | is ε, in response to the modulus value | | | F (P)⁽ⁱ⁾) If | | is less than the threshold value epsilon, the modulus | | | F (P)⁽ⁱ⁾) And taking the value of the iteration variable corresponding to the | | as the accurate value of the parameter of the S curve. Furthermore, the accurate value of the parameter of the S curve in the magnetization process is substituted into the S curve formula, and the magnetization curve equation or the demagnetization curve equation of the magnetic core hysteresis loop can be obtained. Of course, if F (P)⁽ⁱ⁾) When | | | is greater than or equal to a preset threshold epsilon, P is used⁽ⁱ⁺¹⁾The iterative operation is continued for the initial value of the iterative variable until | F (P)⁽ⁱ⁾) And when the | | | is smaller than a preset threshold epsilon, ending each parameter iteration process of the S curve formula in the magnetization process. The modulus | | F (P) is⁽ⁱ⁾) The smaller the | | is, the closer the representation is to the iteration target, and the more accurate the parameters of the obtained S-curve are.

In some embodiments, after obtaining the hysteresis loop, the average power loss of the core can be determined by integrating the hysteresis loop according to the equation of the hysteresis loop and directly according to the definition of the core loss.

In some embodiments, the core loss calculation is formulated as:

in the formula (5), the first and second groups,

the average power loss of the magnetic core in unit volume and unit time is shown as f, the waveform frequency of the current is shown as L, the integral path of the integral along the hysteresis loop is shown as L, the magnetic induction intensity generated by the magnetic core is shown as B, and the magnetic field intensity is shown as H.

Further, for the off-distortion current waveform shown in fig. 2, the core loss calculation formula can also be expressed as:

in the formula (6), H_1minFor the current applied in the cycle to reach the magnetic field strength, H, corresponding to the start of the cut-off current_2minFor the magnetic field strength, H, corresponding to the end of the off-current for the current applied in the cycle_maxFor the magnetic field strength corresponding to the maximum applied current, B₁(H) Is the magnetic induction corresponding to the demagnetization curve when the magnetic field strength H changes within the corresponding integration interval, B₂(H) Is the magnetic induction corresponding to the magnetization curve when the magnetic field strength H varies within the corresponding integration interval.

According to the method for determining the magnetic core loss aiming at the current cut-off distortion of the integrated circuit, a plurality of characteristic points of the magnetic core of the inductance element in the integrated power supply circuit system are collected, and then parameters of an S curve used for fitting a magnetic core hysteresis loop are determined through the characteristic points so as to fit the hysteresis loop of the magnetic core, and finally, the magnetic core loss of the inductance element can be obtained through a method of integrating the hysteresis loop directly according to the definition of the magnetic core loss. Based on the above, the problem that the magnetic core loss is difficult to accurately obtain under the condition of direct current bias in the prior art can be solved, and a convenient and accurate mode is provided for determining the magnetic core loss of the inductance element.

Fig. 5 is a schematic structural diagram of a core loss determination apparatus for integrated circuit current cutoff distortion according to an exemplary embodiment of the present application.

As shown in fig. 5, the present application further provides a core loss determining apparatus for current cut-off distortion of an integrated circuit, which may include: a current supply module 1, an acquisition module 2, a fitting module 3 and a loss determination module 4. The current supply module 1 applies a current having a cut-off distortion waveform, in which the current periodically changes, to a magnetic core of an inductance element used in an integrated circuit power supply system. The acquisition module 2 acquires a plurality of characteristic points of a magnetic hysteresis loop of the magnetic core under the action of the current, wherein the magnetic hysteresis loop represents the change relation between the magnetic field intensity acting on the magnetic core and the magnetic induction intensity generated by the magnetic core. The fitting module 3 determines parameters for fitting an S-curve of the hysteresis loop according to the plurality of feature points to obtain an equation of the hysteresis loop. The loss determination module 4 is configured to integrate the hysteresis loop according to an equation of the hysteresis loop and based on the definition of the core loss to determine the average power loss of the core, where the calculation formula of the core loss is:

wherein H_1minThe magnetic field strength, H, corresponding to the time at which the current reaches the beginning of the cut-off current in the cycle_2minThe magnetic field strength, H, corresponding to the end of the current at the end of the period_maxThe magnetic field strength corresponding to the peak of the current, B₁(H) Is the magnetic induction corresponding to the demagnetization curve when the magnetic field strength H changes within the corresponding integration interval, B₂(H) Is the magnetic induction corresponding to the magnetization curve when the magnetic field strength H varies within the corresponding integration interval. .

In some embodiments, the step of executing the acquisition module 2 may include: in a plurality of periods of current, a first measuring point, a second measuring point, a third measuring point, a fourth measuring point, a fifth measuring point, a sixth measuring point and a seventh measuring point which are used for preliminarily characterizing a hysteresis loop of a magnetic core are respectively and sequentially collected; and performing averaging processing on the plurality of first measurement points, the plurality of second measurement points, the plurality of third measurement points, the plurality of fourth measurement points, the plurality of fifth measurement points, the plurality of sixth measurement points and the plurality of seventh measurement points respectively to obtain a first characteristic point, a second characteristic point, a third characteristic point, a fourth characteristic point, a fifth characteristic point, a sixth characteristic point and a seventh characteristic point, which are used for stably characterizing the hysteresis loop of the magnetic core.

In some embodiments, the characteristic point is a set of pairs having a correspondence relationship between a magnetic field intensity value applied to the magnetic core and a magnetic induction intensity value generated by the magnetic core, wherein the characteristic point includes: a first characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value when the magnetic induction intensity value generated by the magnetic core in the magnetization process reaches reverse saturation, and a reverse magnetic induction intensity saturation value of the magnetic core in the magnetization process; the second characteristic point is composed of a value zero and a residual magnetic induction intensity value of the magnetic core in the magnetization process; a third characteristic point consisting of a coercive force value of the material of the magnetic core in the magnetization process and a numerical value of zero; a fourth characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic induction intensity value reaches the forward saturation and a forward magnetic induction intensity saturation value of the magnetic core; a fifth characteristic point consisting of a value zero and a residual magnetic induction intensity value of the magnetic core in the demagnetization process; a sixth characteristic point which consists of the coercive force value of the material of the magnetic core in the demagnetization process and the numerical value of zero; and a seventh characteristic point consisting of a magnetic field intensity value corresponding to the magnetic field intensity value when the magnetic induction intensity value generated by the magnetic core reaches reverse saturation in the demagnetization process, and a reverse magnetic induction intensity saturation value of the magnetic core in the demagnetization process.

In some embodiments, the implementation of the fitting module 3 may include: according to the attribute that the output result converges to a fixed value when the variable of the S curve tends to infinity, the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the magnetization process reaching reverse saturation and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the demagnetization process reaching reverse saturation are both set to be negative infinity, and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core reaching forward saturation is set to be positive infinity. And respectively substituting the first characteristic point, the second characteristic point, the third characteristic point and the fourth characteristic point into the S curve to determine the initial value of the parameter of the S curve corresponding to the magnetization process. And determining the accurate value of the parameter of the S curve corresponding to the magnetization process by adopting a Newton iteration method so as to determine the magnetization curve equation of the magnetic core. And respectively substituting the fourth characteristic point, the fifth characteristic point, the sixth characteristic point and the seventh characteristic point into the S curve to determine the initial value of the parameter of the S curve corresponding to the demagnetization process. And determining the accurate value of the parameter of the S curve corresponding to the demagnetization process by adopting a Newton iteration method so as to determine the demagnetization curve equation of the magnetic core. And integrating the magnetization curve equation and the demagnetization curve equation to obtain a magnetic hysteresis loop of the magnetic core.

In some embodiments, the newton's iterative method comprises: and respectively determining each parameter of the S curve as an iteration variable. From the iteration variable, a newton iteration formula is determined, where the newton iteration formula represents a formula for deriving a next value of the iteration variable from a previous value of the iteration variable. Determining a target function of the iteration variable, and taking a value of the iteration variable corresponding to the module value as an accurate value of a parameter of the S curve in response to the condition that the module value of the target function is smaller than a preset threshold value; wherein the objective function characterizes a difference between a calculated value at a position of the feature point obtained using an S-curve with an iteration variable as a parameter and a measured value at the position of the feature point.

In some embodiments, the core loss calculation is formulated as:

wherein the content of the first and second substances,

the average power loss of the magnetic core in unit volume and unit time is shown as f, the waveform frequency of the current is shown as L, the integral path of the integral along the hysteresis loop is shown as L, the magnetic induction intensity generated by the magnetic core is shown as B, and the magnetic field intensity is shown as H.

According to the device for determining the magnetic core loss of the integrated circuit current cut-off distortion, a plurality of characteristic points of the magnetic core of the inductance element in the integrated power supply circuit system are collected, and then parameters of an S curve used for fitting a magnetic core hysteresis loop are determined through the characteristic points so as to fit the hysteresis loop of the magnetic core, and finally, the magnetic core loss of the inductance element can be obtained through a method of integrating the hysteresis loop directly according to the definition of the magnetic core loss. Based on the above, the problem that the magnetic core loss is difficult to accurately obtain under the condition of direct current bias in the prior art can be solved, and a convenient and accurate mode is provided for determining the magnetic core loss of the inductance element.

The objects, technical solutions and advantageous effects of the present invention are further described in detail with reference to the above-described embodiments. It should be understood that the above description is only a specific embodiment of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (4)

1. A method for determining core loss for distortion of current cutoff of an integrated circuit, comprising:

applying a current having a cut-off distortion waveform to a magnetic core of an inductive element for an integrated circuit power supply system, wherein the current varies periodically;

under the effect of electric current, gather a plurality of characteristic points of the magnetic hysteresis loop of magnetic core, wherein the magnetic hysteresis loop represents the magnetic field intensity that acts on the magnetic core and the change relation of the magnetic induction intensity that the magnetic core produced, include: in a plurality of periods of the current, a first measuring point, a second measuring point, a third measuring point, a fourth measuring point, a fifth measuring point, a sixth measuring point and a seventh measuring point which are used for preliminarily characterizing a hysteresis loop of the magnetic core are respectively and sequentially collected; and averaging the plurality of first measurement points, the plurality of second measurement points, the plurality of third measurement points, the plurality of fourth measurement points, the plurality of fifth measurement points, the plurality of sixth measurement points, and the plurality of seventh measurement points, respectively, to obtain a first feature point, a second feature point, a third feature point, a fourth feature point, a fifth feature point, a sixth feature point, and a seventh feature point for stably characterizing a hysteresis loop of the magnetic core; the characteristic point is a set of pairs with corresponding relations, wherein the pairs are composed of magnetic field intensity values acting on the magnetic core and magnetic induction intensity values generated by the magnetic core, and the characteristic point comprises the following components: the first characteristic point is composed of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core in the magnetization process when the magnetic induction intensity value reaches reverse saturation and a reverse magnetic induction intensity saturation value of the magnetic core in the magnetization process; the second characteristic point is composed of a value zero and a residual magnetic induction strength value of the magnetic core in the magnetization process; the third characteristic point is composed of a coercive force value of the material of the magnetic core in the magnetization process and a numerical value of zero; the fourth characteristic point is composed of a magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core when the magnetic induction intensity value reaches the forward saturation and a forward magnetic induction intensity saturation value of the magnetic core; the fifth characteristic point consists of a value zero and a residual magnetic induction strength value of the magnetic core in a demagnetization process; the sixth characteristic point consists of a coercive force value of the material of the magnetic core in the demagnetization process and a numerical value of zero; and the seventh characteristic point is composed of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic field intensity value reaches reverse saturation in the demagnetization process and a reverse magnetic induction intensity saturation value of the magnetic core in the demagnetization process;

determining parameters for fitting an S-curve of the hysteresis loop according to the plurality of characteristic points to obtain an equation of the hysteresis loop, including: according to the attribute that the output result converges to a fixed value when the variable of the S curve tends to infinity, setting the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the magnetizing process reaching reverse saturation and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the demagnetizing process reaching reverse saturation as negative infinity, and setting the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core reaching forward saturation as positive infinity; respectively substituting the first characteristic point, the second characteristic point, the third characteristic point and the fourth characteristic point into the S curve to determine an initial value of a parameter of the S curve corresponding to the magnetization process; determining the accurate value of the parameter of the S curve corresponding to the magnetization process by adopting a Newton iteration method so as to determine the magnetization curve equation of the magnetic core; respectively substituting the fourth characteristic point, the fifth characteristic point, the sixth characteristic point and the seventh characteristic point into the S curve to determine an initial value of a parameter of the S curve corresponding to the demagnetization process; determining the accurate value of the parameter of the S curve corresponding to the demagnetization process by adopting a Newton iteration method so as to determine the demagnetization curve equation of the magnetic core; integrating the magnetization curve equation and the demagnetization curve equation to obtain a magnetic hysteresis loop of the magnetic core; and

according to the equation of the magnetic hysteresis loop and based on the definition of the magnetic core loss, integrating the magnetic hysteresis loop to determine the average power loss of the magnetic core, wherein the calculation formula of the magnetic core loss is as follows:

wherein H_1minFor the magnetic field strength, H, corresponding to the time at which the current reaches the beginning of the cut-off current in the period_2minThe magnetic field strength, H, corresponding to the end of the period when the current reaches the cut-off current_maxIs the magnetic field strength corresponding to the peak of the current, B₁(H) Is the magnetic induction corresponding to the demagnetization curve when the magnetic field strength H changes within the corresponding integration interval, B₂(H) For the magnetic induction corresponding to the magnetization curve when the magnetic field strength H varies within the corresponding integration interval, B_1minIs the saturation value of the reverse magnetic induction intensity of the magnetic core in the demagnetization process, B_2minIs the saturation value of the reverse magnetic induction intensity of the magnetic core in the magnetization process.

2. The method of claim 1, wherein the newton's iterative method comprises:

determining each parameter of the S curve as an iteration variable;

determining a newton iteration formula from the iteration variable, wherein the newton iteration formula represents a formula for deriving a next value of the iteration variable from a previous value of the iteration variable; and

determining an objective function of the iteration variable, and taking a value of the iteration variable corresponding to a module value as an accurate value of a parameter of the S curve in response to the condition that the module value of the objective function is smaller than a preset threshold value; wherein the objective function characterizes a difference between a calculated value at the feature point position obtained using an S-curve with the iteration variable as a parameter and a measured value at the feature point position.

3. A core loss determination apparatus for distortion of current cutoff of an integrated circuit, comprising:

a current supply module, which applies current with cut-off distortion waveform to a magnetic core of an inductance element used for an integrated circuit power supply system, wherein the current is periodically changed;

the acquisition module is used for acquiring a plurality of characteristic points of a magnetic hysteresis loop of the magnetic core under the action of the current, wherein the magnetic hysteresis loop represents the change relation between the magnetic field intensity acting on the magnetic core and the magnetic induction intensity generated by the magnetic core, and the execution steps comprise: in a plurality of periods of the current, a first measuring point, a second measuring point, a third measuring point, a fourth measuring point, a fifth measuring point, a sixth measuring point and a seventh measuring point which are used for preliminarily characterizing a hysteresis loop of the magnetic core are respectively and sequentially collected; and averaging the plurality of first measurement points, the plurality of second measurement points, the plurality of third measurement points, the plurality of fourth measurement points, the plurality of fifth measurement points, the plurality of sixth measurement points, and the plurality of seventh measurement points, respectively, to obtain a first feature point, a second feature point, a third feature point, a fourth feature point, a fifth feature point, a sixth feature point, and a seventh feature point for stably characterizing a hysteresis loop of the magnetic core, where the feature points are a set of pairs having correspondence relationships between magnetic field intensity values acting on the magnetic core and magnetic induction intensity values generated by the magnetic core, where the feature points include: the first characteristic point is composed of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core in the magnetization process when the magnetic induction intensity value reaches reverse saturation and a reverse magnetic induction intensity saturation value of the magnetic core in the magnetization process; the second characteristic point is composed of a value zero and a residual magnetic induction strength value of the magnetic core in the magnetization process; the third characteristic point is composed of a coercive force value of the material of the magnetic core in the magnetization process and a numerical value of zero; the fourth characteristic point is composed of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic induction intensity value reaches the forward saturation value and the forward magnetic induction intensity saturation value of the magnetic core; the fifth characteristic point is composed of a value zero and a residual magnetic induction strength value of the magnetic core in the demagnetization process; the sixth characteristic point consists of a coercive force value of the material of the magnetic core in the demagnetization process and a numerical value of zero; and the seventh characteristic point is composed of a magnetic field intensity value corresponding to the magnetic field intensity value generated by the magnetic core when the magnetic field intensity value reaches reverse saturation in the demagnetization process and a reverse magnetic induction intensity saturation value of the magnetic core in the demagnetization process;

the fitting module determines parameters of an S curve for fitting the hysteresis loop according to the plurality of characteristic points to obtain an equation of the hysteresis loop, and the implementation mode of the fitting module comprises the following steps: according to the attribute that the output result converges to a fixed value when the variable of the S curve tends to infinity, setting the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the magnetizing process reaching reverse saturation and the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core in the demagnetizing process reaching reverse saturation as negative infinity, and setting the magnetic field intensity value corresponding to the magnetic induction intensity value generated by the magnetic core reaching forward saturation as positive infinity; respectively substituting the first characteristic point, the second characteristic point, the third characteristic point and the fourth characteristic point into the S curve to determine an initial value of a parameter of the S curve corresponding to the magnetization process; determining the accurate value of the parameter of the S curve corresponding to the magnetization process by adopting a Newton iteration method so as to determine the magnetization curve equation of the magnetic core; respectively substituting the fourth characteristic point, the fifth characteristic point, the sixth characteristic point and the seventh characteristic point into the S curve to determine an initial value of a parameter of the S curve corresponding to the demagnetization process; determining the accurate value of the parameter of the S curve corresponding to the demagnetization process by adopting a Newton iteration method so as to determine the demagnetization curve equation of the magnetic core; integrating the magnetization curve equation and the demagnetization curve equation to obtain a magnetic hysteresis loop of the magnetic core; and

and the loss determining module is used for integrating the hysteresis loop according to the equation of the hysteresis loop and based on the definition of the magnetic core loss to determine the average power loss of the magnetic core, wherein the calculation formula of the magnetic core loss is as follows:

wherein H_1minFor the magnetic field strength, H, corresponding to the time at which the current reaches the beginning of the cut-off current in the period_2minThe magnetic field strength, H, corresponding to the end of the period when the current reaches the cut-off current_maxIs the magnetic field strength corresponding to the peak of the current, B₁(H) Is the magnetic induction corresponding to the demagnetization curve when the magnetic field strength H changes within the corresponding integration interval, B₂(H) For the magnetic induction corresponding to the magnetization curve when the field strength H varies within the corresponding integration interval, B_1minIs the saturation value of the reverse magnetic induction intensity of the magnetic core in the demagnetization process, B_2minIs the saturation value of the reverse magnetic induction intensity of the magnetic core in the magnetization process.

4. The apparatus of claim 3, wherein the Newton's iterative method comprises:

determining each parameter of the S curve as an iteration variable;

determining a newton iteration formula from the iteration variable, wherein the newton iteration formula represents a formula for deriving a next value of the iteration variable from a previous value of the iteration variable; and

determining an objective function of the iteration variable, and taking a value of the iteration variable corresponding to a module value as an accurate value of a parameter of the S curve in response to the condition that the module value of the objective function is smaller than a preset threshold value; wherein the objective function characterizes a difference between a calculated value at the feature point position obtained using an S-curve with the iteration variable as a parameter and a measured value at the feature point position.

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