CN111044956B

CN111044956B - Hysteresis loss estimation method

Info

Publication number: CN111044956B
Application number: CN201911188145.8A
Authority: CN
Inventors: 马吉恩; 方攸同; 陈建尹; 张健; 邱麟
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2021-05-11
Anticipated expiration: 2039-11-28
Also published as: CN111044956A

Abstract

The invention discloses a hysteresis loss estimation method, which comprises the following steps: s10, preparing a group of square columnar ferromagnetic material samples with the same material, the same length and different cross-section sizes; s20, obtaining a B-H curve by using a B-H analyzer; s30, calculating a unit mass iron loss value of each sample, recording the size and the unit iron loss value of each sample, drawing a scatter diagram corresponding to the iron loss and the cross section size, obtaining a numerical value of an iron loss-cross section size curve when the cross section size is 0 by a polynomial and epitaxial method, obtaining the separated hysteresis loss, and further obtaining a hysteresis loop of the material under the unit mass condition; s40, changing the initial value, the final value and the magnetization rate of the magnetic induction intensity of the applied external magnetic field, repeating the steps S20 and S30 to obtain the hysteresis loss and the hysteresis loop of the material under different excitation conditions, and establishing a database; s50, an estimate of hysteresis loss is obtained for a complicated and arbitrary magnetic field excitation condition.

Description

Hysteresis loss estimation method

Technical Field

The invention belongs to the technical field of electromagnetic fields, and particularly relates to a hysteresis loss estimation method.

Background

The research on the motor loss has great environmental protection and engineering significance, and the estimation of the motor iron loss is always a great problem which puzzles the academic and scientific communities. The Steinmetz formula recognized by core manufacturers today has only a high accuracy under sinusoidal excitation conditions. However, the structural features of the motor itself make ideal sinusoidal excitation conditions extremely difficult to achieve. Meanwhile, the existence of power electronic devices such as a frequency converter and a switching power supply also makes the non-sine and asymmetry of the magnetic field inside the motor increasingly serious. Therefore, the establishment of an iron loss estimation model under non-sinusoidal and asymmetric excitation conditions has great significance.

At present, as for estimation models of ferromagnetic loss, improved empirical formulas including MSE (mean square error), GSE, SPG, etc. suitable for different situations have been proposed by scholars. These formulas have good accuracy under certain and limited conditions. The universality of these estimation models has not been effectively demonstrated.

Meanwhile, the separation of the hysteresis loss and the eddy current loss in the iron loss is a great problem in estimating the iron loss because the hysteresis loss and the eddy current loss have distinct occurrence principles. Although the learner proposes an iron loss separation model based on the Steinmetz formula, on the one hand, the accuracy of this model is difficult to verify in the epstein square circle experiment, which is the current mainstream method for measuring iron loss; on the other hand, this model is only applicable for sinusoidal excitation conditions. Therefore, the separation of the iron loss by the new measurement means and the technical route is very important for the estimation of the iron loss. In summary, existing estimation and measurement approaches have been difficult to meet the core loss estimation requirements of ferromagnetic materials under increasingly complex excitation conditions.

Disclosure of Invention

In view of the above technical problems, the present invention is directed to provide a hysteresis loss estimation method, in which a new measurement means based on a combination of a smaller-sized test sample and a B-H analyzer is used to replace the mainstream epstein square circle, so as to accurately measure and separate the iron loss, and on the basis, a database of hysteresis loss is established, and then the hysteresis loss is accurately estimated by using the database as a basis and using an interpolation and table lookup method.

In order to solve the technical problems, the invention adopts the following technical scheme:

a method of estimating hysteresis loss, comprising the steps of:

s10, preparing a group of square columnar ferromagnetic material samples with the same material, the same length and different cross-section sizes;

s20, applying an external magnetic field with the same given magnetic induction material initial value, final value and external magnetic field change rate to the group of samples by using a B-H analyzer to obtain a B-H curve;

s30, calculating a unit mass iron loss value of each sample, recording the size and the unit iron loss value of each sample, drawing a scatter diagram corresponding to the iron loss and the cross section size, obtaining a numerical value of an iron loss-cross section size curve when the cross section size is 0 by a polynomial and epitaxial method, obtaining the separated hysteresis loss, and further obtaining a hysteresis loop of the material under the unit mass condition;

s40, changing the initial value, the final value and the magnetization rate of the magnetic induction intensity of the applied external magnetic field, repeating the steps S20 and S30 to obtain the hysteresis loss and the hysteresis loop of the material under different excitation conditions, and establishing a database;

s50, sampling the excitation under a complex and arbitrary magnetic field excitation condition, connecting data points by line segments to realize piecewise linearization, solving the corresponding initial value, final value and approximate magnetization rate of the magnetic induction intensity for each segment, calling a hysteresis loop database in the database according to the initial value, the final value and the approximate magnetization rate, splicing an estimation model of the hysteresis loop under the excitation condition, and performing numerical integration on the estimation model on the basis to obtain the envelope area of the estimation model so as to obtain the estimation value of the hysteresis loss.

Preferably, the ferromagnetic material sample is a square with the side length of the cross section not more than 0.6mm and the length not more than 5 mm.

Preferably, the complex, arbitrary magnetic field excitation condition is an excitation having a plurality of peaks in each period and a complex change rule of the change rate of the magnetic field.

The invention has the following beneficial effects: applying the same excitation to samples of the same material with different sizes to measure respective B-H curves and corresponding ferromagnetic loss values, and further separating iron loss by an epitaxial method and an interpolation method to obtain unit hysteresis loss of the material and the corresponding B-H curve under the excitation condition; firstly, measuring hysteresis losses and hysteresis loops of different magnetization rates, initial values and final values of magnetic induction intensity under a single-peak excitation condition by using the method to establish a database; and solving the hysteresis loss by adopting a segmented table look-up mode for the situation of any excitation. By introducing a new measurement mode, iron loss separation and hysteresis loss measurement under the condition of low eddy current occupation (small sample size and low external excitation frequency) are realized, a database of hysteresis loss of the ferromagnetic material under different excitation conditions is established on the basis, and the hysteresis loss is accurately estimated by calling and interpolating the database.

Drawings

FIG. 1 is a schematic view of a columnar ferromagnetic material as a sample;

FIG. 2 is a schematic diagram of the principle of the B-H analyzer applying a magnetic field to a sample;

FIG. 3 is a schematic diagram of an original B-H curve obtained by applying a magnetic field to a sample by a B-H analyzer;

FIG. 4 is a schematic diagram of the iron loss separation by interpolation and epitaxy;

FIG. 5 is a schematic illustration of a hysteresis loop as a base data source for a hysteresis loop database;

FIG. 6 is an exemplary graph of the time-varying law of magnetic induction under complex excitation conditions;

fig. 7 is an exemplary diagram of a hysteresis loop corresponding to fig. 6.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a hysteresis loss estimation method, which comprises the following steps:

s10, preparing a set of samples of the same material, the same length, and different cross-sectional dimensions of the square columnar ferromagnetic material (e.g. 50WW470 of non-oriented silicon steel) as shown in fig. 1. In a specific application example, a columnar ferromagnetic material sample with a smaller size (the cross-sectional dimension is a square with a side length of not more than 0.6mm, and the length of not more than 5 mm) is used.

S20, applying an external magnetic field with the same given initial and final magnetic induction and the same change rate of the external magnetic field to the group of materials by using a B-H analyzer (for example, the initial value and the final value of the external magnetic field are both 0.05T and 1.00T, and the change rate of the external magnetic field is both 1T/S), and obtaining a B-H curve as shown in FIG. 3 as shown in FIG. 2.

And S30, calculating the unit mass iron loss value of each sample, recording the size of the sample and the unit iron loss value, and drawing a scatter diagram of the iron loss relative to the cross section size. And then obtaining the value of the iron loss-cross section size curve when the cross section size is 0 by a polynomial interpolation and extension method, as shown in fig. 4. This value is the hysteresis loss isolated. And further obtain a hysteresis loop of the material under the condition of unit mass, as shown in fig. 5. By utilizing the step, the iron loss is measured by unifying the excitation conditions and small samples of the same material with different sizes, and then the loss value when the size is 0, namely the corresponding hysteresis loss value is obtained by an epitaxial method.

S40, changing the initial value, the final value and the magnetization rate of the applied external magnetic field, repeating S20 and S30 to obtain the hysteresis loss and the hysteresis loop of the material under different excitation conditions (for example, given that the difference value between the initial value and the final value of the external magnetic field is 0.1T, the initial value traverses +/-0.1T, +/-0.2T, +/-0.3T, … …, +/-1.8T, the change rate of the external magnetic field traverses 1000e/S, 2000e/S, … … and 10000 e/S), and establishing a database.

S50, for a complex and arbitrary magnetic field excitation condition (excitation having multiple peaks in each period and a complex change rule of the magnetic field change rate, taking fig. 6 as an example), the excitation is sampled, and then data points are connected by line segments to implement piecewise linearization. For each segment, the corresponding initial value, final value and approximate magnetization rate of the magnetic induction intensity are obtained, and a hysteresis loop database is called accordingly, so that an estimation model of the hysteresis loop under the excitation condition is spliced, and numerical integration is performed on the estimation model on the basis to obtain the envelope area of the estimation model so as to obtain an estimated value of the hysteresis loss, see fig. 7, wherein Δ H and Δ B respectively represent the difference between the maximum value and the minimum value of the magnetic induction intensity and the magnetic field intensity between changes in the magnetic field intensity direction every two times. It is verified that the hysteresis loss calculated by the model is consistent with the hysteresis loss separation value obtained by the aforementioned separation method after actual measurement within an error allowable range.

By adopting the small sample for measurement, the proportion of eddy current loss in iron loss is reduced as much as possible, and the precision of a hysteresis loss separation result is improved; meanwhile, the consistency of the magnetic induction intensity applied to the sample and the set intensity is ensured by adopting a high-precision B-H analyzer.

It is to be understood that the exemplary embodiments described herein are illustrative and not restrictive. Although one or more embodiments of the present invention have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

1. A method of estimating hysteresis loss, comprising the steps of:

s20, applying an external magnetic field with the same given magnetic induction initial value, final value and external magnetic field change rate to the group of samples by using a B-H analyzer to obtain a B-H curve;

s40, changing the initial value and the final value of the magnetic induction intensity of the applied external magnetic field and the change rate of the external magnetic field, repeating the steps S20 and S30 to obtain the hysteresis loss and the hysteresis loop of the material under different excitation conditions, and establishing a database;

s50, sampling the excitation under a complex and arbitrary magnetic field excitation condition, connecting data points by line segments to realize piecewise linearization, solving the corresponding initial value and final value of magnetic induction intensity and the change rate of an external magnetic field for each segment, calling a hysteresis loop database in the database according to the change rate, splicing an estimation model of the hysteresis loop under the excitation condition, and performing numerical integration on the estimation model on the basis to obtain the envelope area of the estimation model so as to obtain the estimation value of the hysteresis loss.

2. The hysteresis loss estimation method as claimed in claim 1, wherein the ferromagnetic material samples are squares having a cross-sectional side length of not more than 0.6mm and a length of not more than 5 mm.

3. A method of estimating hysteresis loss as defined in claim 1 or 2, characterized in that the complex, arbitrary magnetic field excitation condition is an excitation having a plurality of peaks per period and a relatively complex law of change of the rate of change of the magnetic field.