JP4275426B2 - Evaluation method, evaluation program and evaluation system for demagnetization of permanent magnet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evaluation method, an evaluation program, and an evaluation system for magnetic field analysis for evaluating demagnetization of a permanent magnet. In particular, the present invention relates to a method for evaluating demagnetization of a permanent magnet using a finite element method or an integral element method. Further, the present invention relates to an evaluation method for evaluating the influence of demagnetization on the characteristics of an electric device equipped with a permanent magnet such as a permanent magnet type motor or a generator using this evaluation method.
[0002]
[Prior art]
Conventionally, there is a method of calculating a demagnetization factor of a permanent magnet from a demagnetization curve and obtaining an average demagnetization factor inside the permanent magnet by calculating a weight using an area. This method is an effective means for obtaining an average demagnetization factor (see Non-Patent Document 1, for example).
[0003]
There is also a method for evaluating the amount of demagnetization by redefining the BH curve (see, for example, Non-Patent Document 2).
[0004]
[Non-Patent Document 1]
Toshiyuki Ishibashi (Yaskawa Electric) “Demagnetizing Conditions and Effects on Embedded Magnet Synchronous Motors”, MAG-01-181, 2001, pp. 61-65 [Non-patent Document 2]
Natsume Tadatoshi, Takabayashi Hirofumi (Sumitomo Special Metals Co., Ltd.) “Examination of Demagnetization Analysis Method of Permanent Magnet”, JMAG Users Conference, October 24-25, 2002, 4-2- Page 4-7 [0005]
[Problems to be solved by the invention]
However, the conventional method is insufficient to know how the generated demagnetization affects the characteristics of electrical equipment such as a motor. In particular, it is not possible to know how cogging torque, torque pulsation, induced voltage waveform, and electromagnetic excitation force of motors and generators change due to demagnetization without performing high-precision magnetic field analysis that reflects the demagnetization factor. There was a problem that it was not possible.
[0006]
Further, the conventional method of redefining the BH curve has a problem that it is impossible to know the change in demagnetization with time.
[0007]
The present invention has been made in order to solve the above-described problems. The first object is to make it possible to improve the accuracy of demagnetization compared to the conventional example, and to more accurately quantify the amount of demagnetization. Evaluation method and evaluation of permanent magnet demagnetization capable of predicting changes in characteristics of rotating machine due to demagnetization (cogging torque, torque pulsation, induced voltage waveform, electromagnetic excitation force, etc.) Obtain programs and evaluation systems.
[0008]
The second object is to obtain an evaluation method, an evaluation program, and an evaluation system for demagnetization of a permanent magnet that can improve the long-term reliability of electrical equipment such as a rotating machine because changes with time can be taken into account. .
[0009]
The third object is to provide an evaluation method, an evaluation program, and an evaluation system for demagnetization of a permanent magnet that can improve the design accuracy by incorporating such an evaluation method into the design of an electrical device having a permanent magnet. To get.
[0010]
[Means for Solving the Problems]
According to the method for evaluating demagnetization of a permanent magnet according to the present invention, the current of the winding of the electric machine of the permanent magnet type motor and the positional relationship between the rotor and the stator are changed, and the permanent magnet of the permanent magnet type motor is predetermined. The permanent magnet is divided into meshes by a magnetic field analysis using a finite element method or an integral element method at each time point exposed to a predetermined magnetic field, and a first demagnetizing factor of each element or each node of the mesh. The step of obtaining the first demagnetization amount and the history, each element of the mesh or each element of the mesh among the first demagnetization factor or the first demagnetization amount of each node obtained at each time point. Obtaining a maximum value of the first demagnetization factor or first demagnetization amount of the node as the second demagnetization factor or second demagnetization amount of each element or each node of the mesh; and each element or each of the mesh At the node 2 to obtain at least one of a residual magnetic flux density, a coercive force, and a demagnetization curve of the permanent magnet according to a demagnetization factor of 2 or a second demagnetization amount, and a second element at each element or node of the mesh. Determining at least one of evaluation examples of cogging torque, on-load torque, and induced voltage of the permanent magnet motor based on the demagnetization factor or the second demagnetization amount .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
A permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of a permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention. In addition, in each figure, the same code | symbol shows the same or equivalent part.
[0012]
In FIG. 1, the evaluation system includes a recording device 1, a demagnetization evaluation means 2, a storage device 3, and an electrical equipment characteristic evaluation means 4. Note that the recording apparatus 1 is not necessarily required as indicated by a broken line.
[0013]
The recording device 1 is composed of, for example, a hard disk device, etc., and includes magnetic field analysis results such as magnetic flux density data, demagnetization evaluation parameter Δ and initial demagnetization factor characteristic data, demagnetization evaluation parameter Δ and time-dependent change rate characteristic data. , BH curve data and the like are stored as a database.
[0014]
The demagnetization evaluation unit 2 and the electrical equipment characteristic evaluation unit 4 are programs that operate on a main body (CPU) such as a personal computer. Further, the storage device 3 is composed of a memory, for example. The demagnetization evaluation means 2 evaluates the demagnetization rate or demagnetization amount of the permanent magnet. Moreover, the electrical equipment characteristic evaluation means 4 evaluates electrical equipment characteristics such as cogging torque, load torque, and induced voltage (refer to Embodiment 5 for detailed description).
[0015]
The demagnetization evaluation means 2 calls the data necessary for demagnetization evaluation such as the magnetic field analysis result, the demagnetization evaluation parameter Δ, the initial demagnetization rate, the change rate with time, and the BH curve from the recording device 1. Then, the demagnetization factor of each part of the permanent magnet is calculated. At that time, data may be exchanged with the storage device 3 as necessary. The result obtained by the demagnetization evaluation means 2 is recorded in the recording device 1.
[0016]
Further, as to how demagnetization affects the electrical equipment, the demagnetization evaluation means 2 passes the demagnetization factor calculation result to the electrical equipment characteristic evaluation means 4. And this electrical equipment characteristic evaluation means 4 calculates characteristics, such as a cogging torque, the torque at the time of load, and an induced voltage.
[0017]
Next, the operation of the permanent magnet demagnetization evaluation system according to the first embodiment will be described with reference to the drawings.
[0018]
FIG. 2 is a flowchart showing the operation of the permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing a specific example of demagnetization evaluation of the permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention.
[0019]
Here, a specific method reflecting demagnetization will be described.
[0020]
First, in step 101, the demagnetization evaluation means 2 calculates demagnetization under magnetic field conditions by magnetic field analysis (existing program).
[0021]
That is, magnetic field analysis is performed to calculate the demagnetization factor or demagnetization amount (physical quantity) in the permanent magnet. As a method for calculating the demagnetization factor or demagnetization amount, a method using the demagnetization evaluation parameter Δ as described in the third embodiment may be used, or a geometry from a demagnetization curve as described in the fourth embodiment. Any other method may be used. Further, the demagnetization rate or the amount of demagnetization in each part of the permanent magnet reflects a history for each evaluation step as will be described later. However, it goes without saying that the number of evaluation steps may be one or two or more (plural).
[0022]
Next, in step 102, it is determined whether demagnetization occurs.
[0023]
Next, when demagnetization occurs in step 103, the history for each evaluation step is followed and the demagnetization rate (demagnetization amount) of each part of the permanent magnet is reflected in the evaluation conditions. As an example, the residual magnetic flux density is changed. Change the coercivity. Change the demagnetization curve.
[0024]
Next, in step 104, evaluation is performed and the influence of demagnetization is examined.
[0025]
That is, when demagnetization occurs, an operation of reflecting the demagnetization rate or demagnetization amount in the next magnetic field analysis is performed. At this time, the magnetic characteristics of the permanent magnet are changed according to the demagnetization rate or the amount of demagnetization. For example, the residual magnetic flux density may be changed, or the coercive force may be changed. Further, the demagnetization curve may be changed. For example, if the demagnetization factor is 1%, the residual magnetic flux density may be 99% before demagnetization.
[0026]
Thus, the magnetic field analysis is performed by reflecting the demagnetization factor in the permanent magnet. In this way, the distribution of magnetic flux density when demagnetization occurs can be obtained. In addition, when the object to be evaluated is an electric device, the change in its characteristics can be known.
[0027]
I will explain a little more in detail. FIG. 3 shows an example of a rectangular parallelepiped permanent magnet 10. In addition, in FIG. 3, since it sees from an axial direction, the permanent magnet 10 is shown as a rectangle.
[0028]
It is assumed that demagnetization occurs around the right shoulder portion of the permanent magnet 10 due to a strong reverse magnetic field applied or a temperature rise. Further, as shown in FIG. 3 (a), the distribution of the demagnetization factor is 1% at the portion of the right shoulder where the demagnetization factor is large (the dense oblique line), 0.5% around it (the coarse oblique line), Further, it is assumed that no demagnetization occurs in the vicinity and the demagnetization factor is 0%. However, in practice, the demagnetization factor varies continuously and is distributed, but here it is assumed to change discretely for simplicity.
[0029]
Next, this demagnetization factor is reflected in the next evaluation. Here, as shown in FIG. 3 (b), we took the approach of changing depending on the demagnetizing factor of the residual magnetic flux density B _r inside the permanent magnet 10. In some cases, the coercive force may be changed, or the demagnetization curve may be changed in accordance with the demagnetization factor in order to consider nonlinearity.
[0030]
In this way, the magnetic field analysis is performed again by reflecting the demagnetization factor in the permanent magnet 10. Here, as shown in FIG. 3C, the magnetic flux density on the straight line connecting the two points X and Y is shown as a graph (curve). Before the demagnetization, the graph A was symmetric. However, when demagnetization occurs around the right shoulder, the graph C of the present embodiment shows the right shoulder portion compared to the graph B of the conventional example. It can be seen that the magnetic flux density is decreasing.
[0031]
Since the conventional evaluation method cannot consider the influence of local demagnetization, an accurate magnetic flux density distribution cannot be predicted. On the other hand, in this embodiment, the magnetic flux density distribution when demagnetization occurs can be known with high accuracy.
[0032]
As described above, the evaluation method according to the present embodiment has an effect that the magnetic flux density distribution when demagnetization occurs in the permanent magnet can be known with high accuracy, and further, the magnetic flux density distribution can be known with high accuracy. There is also an effect that the characteristics of the electric device including the permanent magnet can be known with high accuracy.
[0033]
That is, in the first embodiment, in the method for evaluating the demagnetization of the permanent magnet, the demagnetization rate or demagnetization amount of each part of the permanent magnet is derived, and the demagnetization rate or demagnetization amount of each part of the derived permanent magnet is calculated. The demagnetization factor or demagnetization amount of each part of the permanent magnet is derived by following the history for each evaluation step.
[0034]
Embodiment 2. FIG.
A method for evaluating demagnetization of a permanent magnet according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing a cross-sectional configuration of a permanent magnet type motor according to Embodiment 2 of the present invention.
[0035]
In FIG. 4, the permanent magnet type motor 20 includes a stator core 21, an armature winding 22, a slot 23, a rotor shaft 24, and a permanent magnet 25.
[0036]
In the first embodiment, the description has been made using a very simple model. However, for example, in the case of a permanent magnet type motor 20 as shown in FIG. 4, the current of the electronic winding 22 changes every moment during operation, and the positional relationship between the rotor and the stator also changes every moment. To do. That is, the reverse magnetic field received by the permanent magnet 25 changes every moment.
[0037]
Therefore, when calculating the demagnetizing factor by performing a magnetic field analysis, even if the demagnetizing factor is calculated by paying attention only to a certain time or a certain positional relationship between the rotor and the stator, the distribution of the demagnetizing factor may be different. Conceivable. In such a case, the demagnetization factor is considered to be determined by the worst condition of the reverse magnetic field and temperature experienced by each part of the permanent magnet 25. Therefore, it is necessary to calculate the demagnetization factor following the history of each step of the magnetic field analysis. is there. In the first embodiment, it has been described that the history of the evaluation step is followed, but in this embodiment, the method will be specifically shown.
[0038]
FIG. 5 is a diagram showing a specific example of a method for evaluating demagnetization of a permanent magnet according to Embodiment 2 of the present invention.
[0039]
FIGS. 5A to 5E show how the history for each evaluation step is followed. However, in practice, the demagnetization factor varies continuously and is distributed, but here it is assumed to change discretely for simplicity.
[0040]
In the evaluation step 1, it is assumed that demagnetization has occurred around the left shoulder portion of the permanent magnet 25. In the evaluation step 2 and thereafter, the armature current value and the positional relationship between the rotor and the stator change, and the position where the demagnetization occurs is moved. It is assumed that the demagnetization center moves to the right shoulder of the magnet 25.
[0041]
By following the history from evaluation step 1 to evaluation step N, it is possible to know the demagnetization distribution as shown in FIG.
[0042]
Furthermore, this demagnetization factor distribution is reflected in the next evaluation. Here, the residual magnetic flux density _Br was changed according to the demagnetization factor. As described in the first embodiment, the coercive force may be changed depending on the case, and the demagnetization curve may be changed according to the demagnetization factor in consideration of nonlinearity.
[0043]
By using the method of following the history as described above, there is an effect that the distribution of the demagnetization factor can be obtained quantitatively with high accuracy, and the characteristics of the electric device including the permanent magnet can be obtained by the distribution of the demagnetization factor. There is also an effect that the change can be predicted with high accuracy.
[0044]
FIG. 6 is a diagram showing another specific example of the method for evaluating demagnetization of the permanent magnet according to Embodiment 2 of the present invention.
[0045]
In recent years, with the development of computers, magnetic field analysis using the finite element method, the integral element method, etc. has been active in the design of electrical equipment. In the finite element method, the integral element method, and the like, when modeling a magnetic circuit, the magnet portion is divided into meshes.
[0046]
FIGS. 6A to 6D show a state in which the history of the evaluation step is followed for the mesh-divided permanent magnet. In this case, the demagnetization factor is defined in each element of the mesh of the permanent magnet, and it goes without saying that the demagnetization factor may be defined for the nodes.
[0047]
By following the history of evaluation steps 1 to N, in this case, a result that a region having a demagnetization rate of 1% is distributed on the magnet surface was obtained.
[0048]
In this example, the history of the demagnetization factor is tracked for each element of the mesh, but a plurality of elements can be handled together. In this way, there is an effect that the labor required for model creation and the like is reduced.
[0049]
When tracking the history, if the maximum value of the demagnetization factor or demagnetization amount of each element or node of the mesh is the demagnetization factor or demagnetization amount of that element or node, the demagnetization of the permanent magnet can be performed with higher accuracy. The effect is that the distribution can be predicted. In FIG. 6, for example, when attention is paid to the upper leftmost element of the mesh, the demagnetization factor is 1% in the evaluation step 1, the demagnetization factor is 0% in the evaluation step 2, and the demagnetization factor is 0% in the evaluation step N. Therefore, the maximum value of the demagnetization factor of this element is 1%.
[0050]
Embodiment 3 FIG.
A method for evaluating demagnetization of a permanent magnet according to Embodiment 3 of the present invention will be described with reference to the drawings.
[0051]
Conventionally, research has been made on thermal demagnetization of permanent magnets. For example, the document “Flux Conditions of Permanent Magnet Magnetic Circuit Considering Long-Term Stability”, IEEJ Transactions 1998 proposes a parameter for evaluating thermal demagnetization, and the magnitude of this parameter is related to thermal demagnetization. It is stated that it will have a big impact.
[0052]
The parameters are the residual magnetic flux density of the permanent magnet is B _r [T], the coercive force is _i H _c [A / m], the recoil permeability is μ _r [H / m], and the operation of each part of the permanent magnet When the magnetic field at the point is H [A / m] (where H is defined as the absolute value of the magnetic field at the operating point), it is expressed by the following equation (1).
[0053]
Δ = {μ _r ( _i H _c −H)} / B _r (1)
[0054]
In general, demagnetization of a permanent magnet is divided into an initial demagnetization that occurs when the permanent magnet is exposed to a certain reverse magnetic field and a certain temperature condition, and a change over time that varies depending on the time of exposure to the state. The characteristics of the parameter Δ, the initial demagnetization factor, and the change rate with time of the equation (1) can be obtained by actual measurement.
[0055]
FIG. 7 is a diagram showing the relationship between the parameter Δ and the initial demagnetization factor according to Embodiment 3 of the present invention. In FIG. 7, the vertical axis represents the initial demagnetization factor [%]. The horizontal axis represents the parameter Δ. The further away from the origin, the larger the values.
[0056]
FIG. 8 is a diagram showing the relationship between the parameter Δ and the rate of change with time according to Embodiment 3 of the present invention. In FIG. 8, the vertical axis represents the rate of change with time [%]. The horizontal axis represents the parameter Δ. The further away from the origin, the larger the values.
[0057]
7 and 8, the smaller the parameter Δ, the greater the initial demagnetization rate and the rate of change with time. In the first and second embodiments, the calculation method of the demagnetization factor or demagnetization amount has not been described, but there is a method using the characteristics of the parameter Δ, the initial demagnetization factor, and the change rate with time shown in FIGS. For example, the parameter Δ of each element or each node can be obtained in the finite element method evaluation. The demagnetizing factor of each element or each node can be calculated from this parameter Δ and the characteristics shown in FIGS.
[0058]
The method of calculating the demagnetization factor or demagnetization amount only from the initial demagnetization characteristics shown in FIG. 7 is to predict the amount and distribution of demagnetization when a large current flows due to a sudden short circuit in a motor or a generator. There is an effect that can be.
[0059]
Moreover, since the demagnetization rate or demagnetization amount after exposure for a certain period of time can be calculated from the initial demagnetization and change with time shown in FIGS. 7 and 8, the motor or generator was operated for a long time. There is an effect that the amount and distribution of subsequent demagnetization can be predicted.
[0060]
In addition, since the method using the parameter Δ in Expression (1) is a method based on actual measurement, there is an effect that the amount and distribution of demagnetization can be predicted with high accuracy.
[0061]
Furthermore, in the conventional example for redefining the BH curve, data must be prepared according to the type of permanent magnet. However, the parameter Δ used in the present embodiment is different for a rare earth magnet, for example. Since it has almost constant characteristics, there is an effect that it is possible to evaluate the demagnetization of various permanent magnets with only one kind of relationship between the parameter Δ and the initial demagnetization factor and the relationship between the parameter Δ and the change rate with time. .
[0062]
Embodiment 4 FIG.
A method for evaluating demagnetization of a permanent magnet according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 9 is a diagram showing an example of obtaining the demagnetization factor by plotting according to the fourth embodiment of the present invention.
[0063]
In the above-described third embodiment, the method using the parameter Δ for evaluating demagnetization is used, but there is also a method for obtaining geometrically as is well known.
[0064]
In FIG. 9, the vertical axis represents the magnetic flux density B and the magnetization J. The horizontal axis represents the magnetic field H. The demagnetizing amount ΔB when the operating point is changed by receiving a reverse magnetic field of ΔH from the state at the operating point 41 and the magnetic field is removed again and returned to the original is as in the operating point 41 → 42 → 43 → 44 → 45. Can be sought.
[0065]
Since this method can calculate the initial demagnetization from the demagnetization curve, there is an effect that the demagnetization amount can be estimated relatively easily unlike the method using the parameter Δ in the equation (1).
[0066]
Embodiment 5 FIG.
A method for evaluating demagnetization of a permanent magnet according to Embodiment 5 of the present invention will be described with reference to the drawings. FIG. 10 is a diagram showing an evaluation model for a permanent magnet type motor according to Embodiment 5 of the present invention. Moreover, FIG. 11 is a figure which shows an example (demagnetization factor and its distribution) of the result of the demagnetization evaluation which concerns on Embodiment 5 of this invention.
[0067]
In FIG. 10, a permanent magnet motor evaluation model 50 includes models of respective parts of a stator core 51, an armature winding 52, a rotor shaft 54, and a permanent magnet 55.
[0068]
FIG. 11 shows the demagnetization factor obtained by conducting a magnetic field analysis using the evaluation model 50 for the permanent magnet motor and assuming that a current much larger than the rated current flows.
[0069]
As shown in FIG. 11, demagnetization was confirmed at the portion where the magnetomotive force in the reverse direction is applied to the permanent magnet 55. This result is a result of following a history for each evaluation step in which the rotor position and the current value change.
[0070]
Furthermore, the distribution of the demagnetization factor was reflected in the evaluation, and the cogging torque, the torque waveform at the time of loading, and the induced voltage waveform were evaluated. The results are shown in FIGS.
[0071]
FIG. 12 is a diagram showing an evaluation example of cogging torque according to the fifth embodiment of the present invention. In FIG. 12, the vertical axis represents cogging torque [Nm]. The horizontal axis represents the rotor position [degree (electrical angle)]. The broken line waveform represents before demagnetization, and the solid line waveform represents after demagnetization.
[0072]
Moreover, FIG. 13 is a figure which shows the example of evaluation of the torque at the time of the load which concerns on Embodiment 5 of this invention. In FIG. 13, the vertical axis represents torque [Nm]. The horizontal axis represents the rotor position [degree (electrical angle)]. The broken line waveform represents before demagnetization, and the solid line waveform represents after demagnetization.
[0073]
FIG. 14 is a diagram showing an evaluation example of the induced voltage waveform according to the fifth embodiment of the present invention. In FIG. 14, the vertical axis represents the no-load induced voltage [V]. The horizontal axis represents the rotor position [degree (electrical angle)]. The broken line waveform represents before demagnetization, and the solid line waveform represents after demagnetization.
[0074]
Even if the design reduces cogging torque and torque pulsation, it can be seen that cogging torque and torque pulsation differ if demagnetization occurs due to a large current flowing for some reason. Furthermore, it can be seen that the induced voltage waveform also changes slightly.
[0075]
Needless to say, it is possible to evaluate electromagnetic excitation force related to sound and vibration.
[0076]
Thus, when demagnetization occurs, it is possible to predict how much the motor characteristics are affected.
[0077]
By using such an evaluation method, there is an effect that the design of the permanent magnet type rotating machine can be made highly accurate. Furthermore, it is possible to predict the characteristics of the equipment when a large current flows through the permanent magnet type rotating machine or when the temperature becomes high, so these can be fed back to the design to improve the reliability of electrical design and magnetic circuit design. There is an effect that improvement can be achieved.
[0078]
【The invention's effect】
As described above, the evaluation method of demagnetization of the permanent magnet according to the present invention can know the magnetic flux density distribution when the demagnetization occurs in the permanent magnet with high accuracy, and further know the magnetic flux density distribution with high accuracy. Thus, there is an effect that the characteristics of the electric device including the permanent magnet can be known with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing the configuration of a permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention;
FIG. 2 is a flowchart showing the operation of the permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention;
FIG. 3 is a diagram showing a specific example of demagnetization evaluation of the permanent magnet demagnetization evaluation system according to Embodiment 1 of the present invention;
FIG. 4 is a diagram showing a cross-sectional configuration of a permanent magnet type motor according to a second embodiment of the present invention.
FIG. 5 is a diagram showing a specific example of a method for evaluating demagnetization of a permanent magnet according to Embodiment 2 of the present invention.
FIG. 6 is a diagram showing another specific example of a method for evaluating demagnetization of a permanent magnet according to Embodiment 2 of the present invention.
FIG. 7 is a diagram showing a relationship between a parameter Δ and an initial demagnetization factor according to Embodiment 3 of the present invention.
FIG. 8 is a diagram showing a relationship between a parameter Δ and a rate of change with time according to Embodiment 3 of the present invention.
FIG. 9 is a diagram showing an example of obtaining a demagnetizing factor by plotting according to the fourth embodiment of the present invention.
FIG. 10 is a diagram showing an evaluation model for a permanent magnet type motor according to Embodiment 5 of the present invention;
FIG. 11 is a diagram showing an example of a demagnetization evaluation result (demagnetization factor and its distribution) according to Embodiment 5 of the present invention;
FIG. 12 is a diagram showing an evaluation example of cogging torque according to the fifth embodiment of the present invention.
FIG. 13 is a diagram showing an evaluation example of torque at the time of loading according to Embodiment 5 of the present invention.
FIG. 14 is a diagram showing an evaluation example of an induced voltage waveform according to the fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Recording device, 2 Demagnetization evaluation means, 3 Memory | storage device, 4 Electric equipment characteristic evaluation means, 10 Permanent magnet, 20 Permanent magnet type motor, 21 Stator iron core, 22 Armature winding, 23 slots, 24 Rotor shaft, 25 Permanent magnet, 50 Evaluation model for permanent magnet motor.

Claims (5)

At each time when the current of the winding of the motor of the permanent magnet type motor and the positional relationship between the rotor and the stator are changed, the permanent magnet of the permanent magnet type motor is exposed to a predetermined reverse magnetic field and a predetermined temperature. Dividing the permanent magnet into meshes by magnetic field analysis using a finite element method or an integral element method, and obtaining a first demagnetizing factor or a first demagnetizing amount of each element or each node of the mesh;
Of the first demagnetization factor or the first demagnetization amount of each element or each node of the mesh obtained at each time point, which is a history, the first demagnetization factor or the first demagnetization factor of each element or each node of the mesh Obtaining a maximum value of demagnetization amount as a second demagnetization factor or a second demagnetization amount at each element or node of the mesh;
Determining at least one of residual magnetic flux density, coercivity, and demagnetization curve of the permanent magnet according to a second demagnetization factor or a second demagnetization amount at each element or each node of the mesh;
Obtaining at least one of evaluation examples of cogging torque, on-load torque, and induced voltage of the permanent magnet type motor based on a second demagnetization factor or a second demagnetization amount at each element or each node of the mesh; and A method for evaluating the demagnetization of a permanent magnet. The first demagnetization factor or the first demagnetization amount is defined as follows: the residual magnetic flux density of the permanent magnet is B _r , the coercive force is _i H _c , the recoil permeability is μ _r , each element of the mesh, or the magnetic field at each node. When the absolute value of is H,
Δ = {μ _r ( _i H _c −H)} / B _r
2. The method for evaluating demagnetization of a permanent magnet according to claim 1 , wherein the demagnetization is obtained from a parameter Δ represented by: The first demagnetization factor or the first demagnetization amount is defined as follows: the residual magnetic flux density of the permanent magnet is B _r , the coercive force is _i H _c , the recoil permeability is μ _r , each element of the mesh, or the magnetic field at each node. When the absolute value of is H,
Δ = {μ _r ( _i H _c −H)} / B _r
A parameter delta represented in an initial flux loss for said parameter delta, the evaluation method of the demagnetization of the permanent magnet of claim 1, wherein the determining from the temporal change rate for the parameter delta. On the computer
At each time when the current of the winding of the motor of the permanent magnet type motor and the positional relationship between the rotor and the stator are changed, the permanent magnet of the permanent magnet type motor is exposed to a predetermined reverse magnetic field and a predetermined temperature. A step of dividing the permanent magnet into meshes by a magnetic field analysis using a finite element method or an integral element method, and obtaining a first demagnetizing factor or a first demagnetizing amount of each element or each node of the mesh;
Of the first demagnetization factor or the first demagnetization amount of each element or each node of the mesh obtained at each time point, which is a history, the first demagnetization factor or the first demagnetization factor of each element or each node of the mesh A procedure for obtaining the maximum value of the demagnetization amount as the second demagnetization factor or the second demagnetization amount at each element or each node of the mesh;
A procedure for obtaining at least one of a residual magnetic flux density, a coercive force, and a demagnetization curve of the permanent magnet according to a second demagnetization factor or a second demagnetization amount at each element or each node of the mesh;
as well as
Procedure for obtaining at least one of evaluation examples of cogging torque, load torque, and induced voltage of the permanent magnet type motor based on the second demagnetization factor or the second demagnetization amount at each element or each node of the mesh
An evaluation program for permanent magnet demagnetization . At each time when the current of the winding of the motor of the permanent magnet type motor and the positional relationship between the rotor and the stator are changed, the permanent magnet of the permanent magnet type motor is exposed to a predetermined reverse magnetic field and a predetermined temperature. The permanent magnet is divided into meshes by magnetic field analysis using a finite element method or an integral element method, and a first demagnetization factor or a first demagnetization amount of each element or each node of the mesh is obtained.
Of the first demagnetization factor or the first demagnetization amount of each element or each node of the mesh obtained at each time point, which is a history, the first demagnetization factor or the first demagnetization factor of each element or each node of the mesh The maximum value of the demagnetization amount is obtained as the second demagnetization factor or the second demagnetization amount at each element or each node of the mesh,
Demagnetization evaluation means for obtaining at least one of a residual magnetic flux density, a coercive force, and a demagnetization curve of the permanent magnet according to a second demagnetization factor or a second demagnetization amount at each element or each node of the mesh; ,
Based on the second demagnetization factor or the second demagnetization amount at each element or each node of the mesh obtained by the demagnetization evaluation means, an evaluation example of cogging torque, load torque, and induced voltage of the permanent magnet motor Electrical equipment characteristic evaluation means for obtaining at least one of them
A system for evaluating demagnetization of a permanent magnet .

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