CN112152400B - Permanent magnet eddy current loss optimization method - Google Patents

Permanent magnet eddy current loss optimization method Download PDF

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CN112152400B
CN112152400B CN202011011184.3A CN202011011184A CN112152400B CN 112152400 B CN112152400 B CN 112152400B CN 202011011184 A CN202011011184 A CN 202011011184A CN 112152400 B CN112152400 B CN 112152400B
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permanent magnet
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佟文明
孙鲁
吴胜男
张红奎
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Shenyang University of Technology
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Abstract

The invention relates to a permanent magnetThe optimizing method of the body eddy current loss comprises the following steps: 1) Selecting a permanent magnet region of a non-concentric magnetic pole permanent magnet motor, taking a subdomain method model as a basis, and adopting a mixed subdomain method to carry out radial and circumferential subdomain on permanent magnets with different shapes; 2) Constructing a permanent magnet eddy current loss model of the non-concentric magnetic pole permanent magnet motor; 3) Obtaining the eccentricity of the permanent magnet area of the optimized non-concentric magnetic pole permanent magnet motor，And finally, setting a permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the eccentricity. According to the invention, parameters of the non-concentric magnetic poles are optimized to obtain the eccentricity index when the eddy current loss of the rotor is the lowest, and the motor is designed, so that the eddy current loss of a permanent magnet of the motor is reduced. The method solves the problems of low precision, long time, poor universality and the like of the existing method.

Description

Permanent magnet eddy current loss optimization method
Technical Field
The invention relates to the technical field of permanent magnet motor loss, in particular to an optimization method for reducing permanent magnet eddy current loss of a permanent magnet synchronous motor with non-concentric magnetic poles under harmonic conditions.
Background
The non-concentric magnetic pole permanent magnet motor has the advantages of small torque pulsation, high power density and the like, and is widely applied to the field of high-precision servo motors. However, due to poor heat dissipation conditions of the permanent magnet, when the frequency converter supplies power, high-frequency current harmonic waves in the armature winding generate a large amount of eddy current loss in the permanent magnet, so that the temperature rise of the permanent magnet is too high, and the permanent magnet has demagnetizing risks. The non-concentric magnetic poles are widely applied to high-precision permanent magnet servo motors, so that the motor is conveniently designed, and the running stability of the motor is ensured. It is important to quickly and accurately calculate the eddy current loss of permanent magnet under non-concentric magnetic pole
Because of the limitation of the combined boundary conditions of the Norman and the continuity, when the eddy current loss is calculated by the prior subzone method, the non-concentric magnetic pole permanent magnet is mainly equivalent to a rectangular permanent magnet so as to lead the boundaries of all subzones to be parallel, and the equivalent method has low calculation precision. The finite element method is long in calculating time for calculating the eddy current loss of the rotor, the model is poor in universality, and a large amount of time is required for modeling and calculating the high-precision servo permanent magnet motors with different structures, so that the motor design is not facilitated.
Disclosure of Invention
The invention aims to:
the invention provides an optimization method for permanent magnet eddy current loss of a permanent magnet synchronous motor considering non-concentric magnetic poles under harmonic conditions, and aims to solve the problems of low precision, long time, poor universality and the like of the existing method so as to reduce the permanent magnet eddy current loss.
The technical scheme is as follows:
an optimization method of permanent magnet eddy current loss, comprising the following steps:
1) Selecting permanent magnet areas of the non-concentric magnetic pole permanent magnet motor based on a subdomain method model, and adopting a mixed zoning method to perform radial and circumferential zoning on the permanent magnets with different shapes so as to respectively obtain the inner diameter and outer diameter expressions of the permanent magnets with different shapes and the equivalent thickness of the concentric magnetic pole areas and the non-concentric magnetic pole areas of the permanent magnets with different shapes;
2) Constructing a permanent magnet eddy current loss model of the non-concentric magnetic pole permanent magnet motor according to the inner diameter and outer diameter expressions of the permanent magnets with different shapes and the permanent magnet concentric area eddy current expression in the step 1);
3) And (2) obtaining the eccentricity of the optimized permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the equivalent thicknesses of the concentric magnetic pole area and the non-concentric magnetic pole area of the permanent magnet with different shapes in the step (1) and the permanent magnet eddy current loss model in the step (2), and finally setting the permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the eccentricity when the loss in the permanent magnet eddy current loss model is minimum.
In the step 1), the permanent magnet area is divided into a concentric magnetic pole area and a non-concentric magnetic pole area by a radial zoning method, and the non-concentric area is divided into a plurality of areas with equal thickness by a circumferential zoning method.
In the step 1) and the step 2), the permanent magnet is shaped as an outer pole arc chamfer, an arc-shaped permanent magnet chamfer or an inner pole arc chamfer.
In the step (1) of the process,
when the permanent magnet is shaped as an outer pole arc chamfer, the inner diameter and the outer diameter of the permanent magnet in the concentric area part are respectively R rw And R is 1w ；
Non-concentric regionsPart of the inner diameter is R 1w Outer diameter R pmw The expression of (2) is:
Figure BDA0002697613450000021
wherein h is the eccentricity of the permanent magnet, θ 1 R is the circumferential angle of the stationary-coordinate permanent magnet 2w Chamfering the outer pole arc with the chamfering radius of the permanent magnet;
when the permanent magnet is in the shape of an arcuate permanent magnet, the inner and outer diameters of the permanent magnet in the concentric region portion are R rg And R is 1g ；
The non-concentric region portion comprises a chamfered portion and an un-chamfered portion, the chamfered portion radius of the arcuate permanent magnet being:
Figure BDA0002697613450000022
wherein h is the eccentricity of the permanent magnet, θ 1 R is the circumferential angle of the stationary-coordinate permanent magnet 2g The chamfer radius of the arc-shaped permanent magnet;
the radius of the non-chamfered part of the arc-shaped permanent magnet is as follows:
R pmg ＝R 2g
when the permanent magnet is shaped as an inner pole arc chamfer, the outer diameter of the concentric region is a fixed value R nr An inner diameter of R n1 The method comprises the steps of carrying out a first treatment on the surface of the The outer diameter of the non-concentric region is R n1 An inner diameter R nr The expression of (2) is:
Figure BDA0002697613450000023
wherein h is the eccentricity of the outer pole arc chamfer permanent magnet, theta 1 R is the circumferential angle of the stationary-coordinate permanent magnet n1 The outer diameter of the inner pole arc chamfer is formed.
In step 1), when the permanent magnet is shaped as an outer pole arc chamfer, the equivalent thickness of the concentric region is:
d w ＝R 1w -R rw
wherein R is 1w Is the outer diameter of the concentric part, R rw The inner diameter of the permanent magnet is the inner diameter of the permanent magnet;
the equivalent thickness of the permanent magnet per region of the non-concentric region is:
d i ＝R′ pmi -R 1
wherein R 'is' pmgi The outer diameter of the permanent magnet is equal in thickness in each area of the permanent magnet;
when the permanent magnet is in the shape of an arcuate permanent magnet, the equivalent thickness of the concentric region thickness is:
d g ＝R 1g -R rg
wherein R is rg And R is 1g The inner diameter and the outer diameter of the permanent magnet are respectively;
the equivalent thickness of the permanent magnet of each area of the non-concentric area part chamfer part is as follows:
d ig ＝R′ pmgi -R 1g
wherein R 'is' pmgi The equivalent radius of the permanent magnet for each area of the chamfer portion;
the equivalent thickness of the permanent magnet in each area of the non-chamfered portion is:
d g ＝R 2g -R rg
wherein R is 2g The chamfer radius of the arc-shaped permanent magnet;
when the inner pole arc is a chamfer type permanent magnet, the thickness of the concentric part is as follows:
d n ＝R n2 -R n1
wherein R is n2 ，R n1 The outer diameter of the inner pole arc chamfer type permanent magnet and the inner diameter of the concentric part are respectively;
the equivalent thickness of the non-concentric area portion is:
d ni ＝R n1 -R n ′ ri
wherein R 'is' nri The equivalent outer diameter of the permanent magnet of each region, R, being a non-concentric region portion n1 Is the outer diameter of the non-concentric portion.
In step 2), the permanent magnet eddy current loss pattern of the non-concentric pole permanent magnet motor includes a concentric pole region and a permanent magnet eddy current loss pattern of the non-concentric pole region.
The permanent magnet eddy current loss model of the concentric magnetic pole region is:
Figure BDA0002697613450000031
wherein J is III ，H III The current density and the magnetic field intensity in the region are respectively, and L is the axial length of the permanent magnet.
The permanent magnet eddy current loss model of the non-concentric magnetic pole region is:
Figure BDA0002697613450000041
wherein the permanent magnet loss of each circumferential region is:
Figure BDA0002697613450000044
wherein the method comprises the steps of
Figure BDA0002697613450000045
Wherein L is the length of the iron core, and T is the period of the motor.
In the step 3), the loss in the permanent magnet eddy current loss model is minimum, namely, the permanent magnet eddy current loss model is derived.
In step 3), the eccentricity h is:
Figure BDA0002697613450000046
wherein R is r The inner diameter of the permanent magnet is chamfered for the outer pole arc, and d is the thickness of the center of the permanent magnet.
The advantages and effects:
(1) The invention discloses an optimization method for permanent magnet eddy current loss of a permanent magnet synchronous motor considering non-concentric magnetic poles under harmonic conditions. The magnetic pole is divided into concentric and non-concentric areas by adopting a mixed domain dividing method, and the non-concentric areas are circumferentially divided, so that the calculation accuracy is higher compared with the traditional method of equivalently converting the permanent magnet into a rectangular block.
(2) The non-concentric magnetic pole eddy current loss model provided by the invention has good universality, and compared with a finite element method, the modeling and calculating speed is obviously improved in the aspects of motor model structure change, calculating speed and the like.
(3) According to the model provided by the invention, for non-identical magnetic poles with the outer pole arc chamfer, the minimum permanent magnet eddy current loss is taken as a target, and the non-concentric magnetic pole parameters are optimized to obtain the eccentricity index when the rotor eddy current loss is minimum, and the motor is designed, so that the permanent magnet eddy current loss of the motor is reduced.
(4) According to the invention, rotor eddy current loss of a plurality of non-concentric magnetic pole permanent magnet synchronous motors meeting different powers of a geometric similarity law is calculated by using a model based on an analysis method and a classical model based on a time-step finite element respectively, and compared with actual measured rotor eddy current loss, the model constructed by the method has higher precision, and the effectiveness of the model is verified.
Drawings
FIG. 1 is a schematic illustration of an outer pole arc chamfer and arcuate permanent magnet configuration;
FIG. 2 is a schematic view of the structure of an inner pole arc chamfer permanent magnet;
FIG. 3 is a variable frequency power supply no-load condition;
FIG. 4 is a graph showing the loss comparison of outer pole arc chamfer permanent magnets and concentric permanent magnets at different rotational speeds;
FIG. 5 is a schematic diagram of non-concentric pole parametric loss variation;
FIG. 6 is a graph comparing experimental and calculated results of a plurality of non-concentric pole permanent magnet motors under variable frequency power supply load conditions;
FIG. 7 is a graph comparing experimental and calculated results of a plurality of non-concentric pole permanent magnet motors under variable frequency power supply no-load conditions;
Detailed Description
The invention is described in more detail below with reference to the drawings accompanying the specification.
The invention provides an optimization method for permanent magnet eddy current loss of a permanent magnet synchronous motor considering non-concentric magnetic poles under harmonic conditions. The method is based on a sub-field method model, adopts a mixed sub-field method to carry out radial and circumferential sub-fields on non-concentric magnetic pole sub-fields, and assumes that the corresponding theta is at the center of a permanent magnet 1 =0, resulting in a radial expression of the non-concentric part of the permanent magnet. The non-concentric magnetic poles are divided into concentric magnetic pole areas and non-concentric magnetic pole areas by a radial zoning method. The non-concentric region is partially divided circumferentially and is equivalent to a permanent magnet region of thickness d. And constructing an eddy current loss analysis model of the non-concentric magnetic pole to calculate the eddy current loss of the permanent magnet synchronous motor of the non-concentric magnetic pole. And the analysis model aims at the minimum eddy current loss of the permanent magnet, and optimization research is carried out on non-concentric magnetic pole parameters so as to reduce the eddy current loss of the permanent magnet of the motor.
An optimization method of permanent magnet eddy current loss, comprising the following steps:
and dividing the non-concentric magnetic pole permanent magnet motor into a slot area, an air gap area, a permanent magnet area and a rotor core area according to the solving conditions of the subdomains.
1) Selecting permanent magnet areas of the non-concentric magnetic pole permanent magnet motor based on a subdomain method model, and adopting a mixed zoning method to perform radial and circumferential zoning on the permanent magnets with different shapes so as to respectively obtain the inner diameter and outer diameter expressions of the permanent magnets with different shapes and the equivalent thickness of the concentric magnetic pole areas and the non-concentric magnetic pole areas of the permanent magnets with different shapes;
the inner diameter and outer diameter of the permanent magnets of different shapes are expressed as follows,
(1) for the permanent magnet with the shape of outer pole arc chamfer, the permanent magnet is radially divided into concentric area parts, and as shown in figure 1, the inner diameter and the outer diameter of the permanent magnet of the concentric area parts are respectively R rw And R is 1w The rest being non-concentric part in whichThe diameter is R 1w Rather than concentric poles, the permanent magnet outer diameter R pmw The expression of (2) is:
Figure BDA0002697613450000061
wherein h is the eccentricity of the outer pole arc chamfer permanent magnet, theta 1 R is the circumferential angle of the stationary-coordinate permanent magnet 2w Is the chamfer radius;
(2) when the permanent magnet is in the shape of an arc-shaped permanent magnet, the permanent magnet is radially divided into a concentric area part and a non-concentric area part, and as shown in figure 1, the inner diameter and the outer diameter of the permanent magnet of the concentric area part are respectively R rg And R is 1g ；
The non-concentric region portion comprises a chamfered portion and an un-chamfered portion, the chamfered portion radius of the arcuate permanent magnet being:
Figure BDA0002697613450000062
wherein h is the eccentricity of the outer pole arc chamfer permanent magnet, theta 1 R is the circumferential angle of the stationary-coordinate permanent magnet 2g Is the chamfer radius of the arcuate permanent magnet.
Non-chamfered portions:
R pmg ＝R 2g (3)
(3) when the permanent magnet is shaped as an inner pole arc chamfer, the permanent magnet is radially divided into a concentric area part and a non-concentric area part, as shown in figure 2, the outer diameter of the concentric area is a fixed value R nr An inner diameter of R n1 The method comprises the steps of carrying out a first treatment on the surface of the The lower half part of the arc chamfer is a non-concentric area part for circumferential zoning, and the outer diameter of the non-concentric area is R n1 An inner diameter R nr The expression of (2) is:
Figure BDA0002697613450000071
wherein h isEccentricity of outer pole arc chamfer permanent magnet, theta 1 R is the circumferential angle of the stationary-coordinate permanent magnet n1 The outer diameter of the inner pole arc chamfer is formed.
The equivalent thicknesses of the concentric and non-concentric pole regions of the different shaped permanent magnets are as follows,
(1) for the permanent magnet, the outer pole arc is shaped, the thickness of the concentric area is constant:
d w ＝R 1w -R rw (5)
wherein R is 1w Is the outer diameter of the concentric part, R rw Is the inner diameter of the permanent magnet.
The outer pole arc chamfer adopts a circumferential domain dividing method in a non-concentric area, and the permanent magnet of each area is equivalent to a permanent magnet with equal thickness, and the outer diameter of the permanent magnet of each area is as follows:
Figure BDA0002697613450000072
wherein alpha is p Is the polar arc coefficient of the permanent magnet, alpha p/ k is the polar arc coefficient of the ith permanent magnet block of the circumferential sub-domain. The thickness of each area permanent magnet is as follows:
d iw ＝R′ pmiw -R 1w (7)
(2) when the permanent magnet is in the shape of an arc-shaped permanent magnet, the thickness of the concentric area of the arc-shaped permanent magnet is the same as that of the concentric part of the outer pole arc-chamfer type permanent magnet, and the equivalent thickness of the concentric area is as follows:
d ig ＝R′ pmgi -R 1g (8)
wherein R is rg And R is 1g Respectively the inner diameter and the outer diameter of the permanent magnet
The equivalent thickness of the permanent magnet of each area of the non-chamfered part is as follows:
d g ＝R 2g -R rg (9)
(3) when the inner pole arc chamfer type permanent magnet is used, the thickness algorithm is the same as that of the outer pole arc chamfer type permanent magnet. The thickness of the concentric portion is:
d n ＝R n2 -R n1 (10)
wherein R is n2 ，R n1 The outer diameter of the permanent magnet with the inner pole arc being chamfered and the inner diameter of the concentric part are respectively
The inner diameter of the non-concentric area portion is:
Figure BDA0002697613450000073
the thickness of the non-concentric area portion is:
d ni ＝R n1 -R′ nri (12)
wherein R 'is' nri Is the inner diameter of the non-concentric zone portion, R n1 Is the outer diameter of the non-concentric portion.
2) Constructing a permanent magnet eddy current loss model of the non-concentric magnetic pole permanent magnet motor according to the inner diameter and outer diameter expressions of the permanent magnets with different shapes and the permanent magnet concentric area eddy current expression in the step 1);
equivalent current sheets uniformly distributed in the notch are equivalent to the armature winding, and then the equivalent current sheet expression is as follows:
Figure BDA0002697613450000081
wherein the method comprises the steps of
J mn ＝3NI n k sov k dp /(πR s ) (14)
The air gap subdomain is poisson equation
Figure BDA0002697613450000082
For equivalent current sheets uniformly distributed in the notch, the general solution is:
Figure BDA0002697613450000083
where a, B are coefficients related to boundary conditions, n, m are time harmonics and space harmonics times, respectively, ωr is the angular speed of the motor, and α, θ are circumferential angles with respect to the rotating coordinate system and the stationary coordinate system, respectively.
Because the permanent magnet is shaped as an inner pole arc chamfer, when the outer pole arc chamfer and the arched permanent magnet chamfer, the radial and circumferential regions are divided, the method for obtaining the permanent magnet eddy current loss model of the non-concentric pole permanent magnet motor is consistent, and the permanent magnet eddy current loss model and the eccentricity h of the non-concentric pole permanent magnet motor are obtained by taking the case that the permanent magnet is shaped as the outer pole arc chamfer as an example.
In the non-concentric area (area II) of the permanent magnet subdomain, the permanent magnets of k areas are equivalent to permanent magnet blocks with equal thickness, and the equivalent radius of each area is as follows:
Figure BDA0002697613450000084
thickness d of permanent magnet i And then the outer diameter of the permanent magnet of each area is as follows:
d i ＝R′ pmi -R 1 (18)
in order to consider the influence of the eddy current reaction field, the diffusion equation of the laplace equation is written by poisson equation as a constraint condition to consider the skin depth of each subharmonic on the permanent magnet. Since the permanent magnet material properties of each region are the same, the eddy current equation generated on each region permanent magnet piece:
Figure BDA0002697613450000091
wherein the method comprises the steps of
Figure BDA0002697613450000092
The eddy current expression on each area permanent magnet is:
Figure BDA0002697613450000093
wherein the method comprises the steps of
i＝1,2,3…k
R 1 ≤r≤R′ pmi (22)
For the concentric area of the permanent magnet subdomain, the inner diameter and the outer diameter of the permanent magnet block are constant and respectively R 1 And R is r . Solving the diffusion equation can result in a permanent magnet concentric region eddy current of:
Figure BDA0002697613450000094
wherein the method comprises the steps of
R r ≤r≤R 1 (24)
To take into account the influence of stator slotting on the eddy current loss of permanent magnets, the flux density is modified by a flux guiding function
Figure BDA0002697613450000095
Wherein l is the number of magnetic permeability harmonics, Z is the number of stator slots, then
Figure BDA0002697613450000096
When the stator and rotor iron core permeability is assumed to be infinite, boundary conditions of interfaces of different subfields are as follows:
Figure BDA0002697613450000097
obtaining the magnetic density of each subdomain through boundary conditions and introducing a Poynting vector calculation area III into a permanent magnet concentric area to calculate the eddy current loss of the permanent magnet as
Figure BDA0002697613450000098
The eddy current loss average value of the non-concentric area of the permanent magnet in one period is
Figure BDA0002697613450000101
The permanent magnet loss per circumferential region is:
Figure BDA0002697613450000102
wherein the method comprises the steps of
Figure BDA0002697613450000103
3) And (2) obtaining the eccentricity h of the optimized permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the equivalent thicknesses of the concentric magnetic pole area and the non-concentric magnetic pole area of the permanent magnet with different shapes in the step (1) and the permanent magnet eddy current loss model in the step (2), and finally setting the permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the eccentricity h when the loss in the permanent magnet eddy current loss model is minimum.
For the shape of the permanent magnet with the outer pole arc chamfered, the formulas (1) (7) (8) are put into the formula (31) and the formula P is analyzed for loss Ⅱ (h) And simplifying and deriving to obtain the relationship between the eccentricity h and the non-concentric magnetic pole parameters when the loss of the permanent magnet is the lowest as follows:
Figure BDA0002697613450000104
wherein R is r The inner diameter of the permanent magnet is chamfered for the outer pole arc, and d is the thickness of the center of the permanent magnet.
Example 1
The eddy current loss of a 6.9kW non-concentric magnetic pole permanent magnet motor with the specification shown in table 1 is calculated by using the model of the invention based on the subdomain method and the mixed domain method and the classical model based on the time-step finite element, the calculation result is shown in fig. 3, the analysis result is slightly lower than the calculation result of the finite element, because the analysis model ignores the eddy current loss of the rotor core, but the calculation speed of the analysis model is far higher than that of the finite element, and the calculation speed is increased by tens of times, as shown in table 2.
Example 2
The eddy current loss of a non-concentric magnetic pole permanent magnet motor of 6.9kw under different rotating speed conditions is calculated by using the model of the invention based on the subdomain method and the mixed domain method and the classical model based on the time-step finite element respectively, as shown in figure 4. It can be seen that the rotor eddy current loss can be effectively reduced by using non-concentric poles for the permanent magnet motor at high rotational speeds.
Example 3
The eddy current loss of a non-concentric magnetic pole permanent magnet motor of 6.9kw in different magnetic pole parameters is calculated by using the model of the invention based on the subdomain method and the mixed domain method and the classical model based on the time-step finite element, as shown in figure 5. It can be seen that the non-concentric magnetic pole parameters can greatly influence the eddy current loss, the eddy current loss can be reduced by adopting proper eccentricity for the permanent magnet with the outer pole arc chamfer, and the calculation result shows that the eccentricity corresponding to the lowest point of the eddy current loss meets the formula (32), so that the accuracy of the analytical model is verified.
Example 4
The model of the invention based on the subdomain method and the mixed domain method and the classical model based on the time-step finite element are respectively utilized, and the eddy current loss of a plurality of non-concentric magnetic pole permanent magnet motors with different powers meeting the geometric similarity theorem is actually measured by adopting an experimental method, as shown in figures 6-7, the analysis result is slightly lower than the experimental value due to neglecting the rotor core loss under the power supply of the frequency converter, but the analysis model still has higher precision and high calculation speed can be seen by the result.
TABLE 1 6.9kw non-concentric pole motor parameters
Figure BDA0002697613450000111
TABLE 2 simulation time comparison of different models
Figure BDA0002697613450000112
Figure BDA0002697613450000121
TABLE 3 variable notes and units
Figure BDA0002697613450000122
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Claims (10)

1. The method for optimizing the eddy current loss of the permanent magnet is characterized by comprising the following steps of: the method comprises the following steps:
1) Selecting permanent magnet areas of the non-concentric magnetic pole permanent magnet motor based on a subdomain method model, and adopting a mixed zoning method to perform radial and circumferential zoning on the permanent magnets with different shapes so as to respectively obtain the inner diameter and outer diameter expressions of the permanent magnets with different shapes and the equivalent thickness of the concentric magnetic pole areas and the non-concentric magnetic pole areas of the permanent magnets with different shapes;
2) Constructing a permanent magnet eddy current loss model of the non-concentric magnetic pole permanent magnet motor according to the inner diameter and outer diameter expressions of the permanent magnets with different shapes and the permanent magnet concentric area eddy current expression in the step 1);
3) And (2) obtaining the eccentricity of the optimized permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the equivalent thicknesses of the concentric magnetic pole area and the non-concentric magnetic pole area of the permanent magnet with different shapes in the step (1) and the permanent magnet eddy current loss model in the step (2), and finally setting the permanent magnet area of the non-concentric magnetic pole permanent magnet motor according to the eccentricity when the loss in the permanent magnet eddy current loss model is minimum.
2. The method for optimizing eddy current loss of a permanent magnet according to claim 1, wherein:
in the step 1), the permanent magnet area is divided into a concentric magnetic pole area and a non-concentric magnetic pole area by a radial zoning method, and the non-concentric area is divided into a plurality of areas with equal thickness by a circumferential zoning method.
3. The method for optimizing eddy current loss of a permanent magnet according to claim 1, wherein:
in the step 1) and the step 2), the permanent magnet is shaped as an outer pole arc chamfer, an arc-shaped permanent magnet chamfer or an inner pole arc chamfer.
4. A method of optimizing eddy current loss of a permanent magnet according to claim 3, wherein: in the step (1) of the process,
when the permanent magnet is shaped as an outer pole arc chamfer, the inner diameter and the outer diameter of the permanent magnet in the concentric area part are respectively R rw And R is 1w ；
The inner diameter of the non-concentric area part is R 1w Outer diameter R pmw The expression of (2) is:
Figure FDA0004100325670000011
wherein h is the eccentricity of the permanent magnet, θ 1 R is the circumferential angle of the stationary-coordinate permanent magnet 2w Chamfering the outer pole arc with the chamfering radius of the permanent magnet;
when the permanent magnet is in the shape of an arcuate permanent magnet, the inner and outer diameters of the permanent magnet in the concentric region portion are R rg And R is 1g ；
The non-concentric region portion comprises a chamfered portion and an un-chamfered portion, the chamfered portion radius of the arcuate permanent magnet being:
Figure FDA0004100325670000012
wherein h is the eccentricity of the permanent magnet, θ 1 R is the circumferential angle of the stationary-coordinate permanent magnet 2g The chamfer radius of the arc-shaped permanent magnet;
the radius of the non-chamfered part of the arc-shaped permanent magnet is as follows:
R pmg ＝R 2g
when the permanent magnet is shaped as an inner pole arc chamfer, the outer diameter of the concentric region is a fixed value R nr An inner diameter of R n1 The method comprises the steps of carrying out a first treatment on the surface of the The outer diameter of the non-concentric region is R n1 An inner diameter R nr The expression of (2) is:
Figure FDA0004100325670000021
wherein h is the eccentricity of the outer pole arc chamfer permanent magnet, theta 1 R is the circumferential angle of the stationary-coordinate permanent magnet n1 The outer diameter of the inner pole arc chamfer is formed.
5. A method of optimizing eddy current loss of a permanent magnet according to claim 3, wherein:
in step 1), when the permanent magnet is shaped as an outer pole arc chamfer, the equivalent thickness of the concentric region is:
d w ＝R 1w -R rw
wherein R is 1w Is the outer diameter of the concentric part, R rw The inner diameter of the permanent magnet is the inner diameter of the permanent magnet;
the equivalent thickness of the permanent magnet per region of the non-concentric region is:
d i ＝R′ pmi -R 1
wherein R 'is' pmi The outer diameter of the permanent magnet is equal in thickness in each area of the permanent magnet; r is R 1 An outer diameter of the concentric portion of the permanent magnet;
when the permanent magnet is in the shape of an arcuate permanent magnet, the equivalent thickness of the concentric region thickness is:
d g ＝R 1g -R rg
wherein R is rg And R is 1g The inner diameter and the outer diameter of the permanent magnet are respectively;
the equivalent thickness of the permanent magnet of each area of the non-concentric area part chamfer part is as follows:
d ig ＝R′ pmgi -R 1g
wherein R 'is' pmgi The equivalent radius of the permanent magnet for each area of the chamfer portion;
the equivalent thickness of the permanent magnet in each area of the non-chamfered portion is:
d g ＝R 2g -R rg
wherein R is 2g The chamfer radius of the arc-shaped permanent magnet;
when the inner pole arc is a chamfer type permanent magnet, the thickness of the concentric part is as follows:
d n ＝R n2 -R n1
wherein R is n2 ，R n1 The outer diameter of the inner pole arc chamfer type permanent magnet and the inner diameter of the concentric part are respectively;
the equivalent thickness of the non-concentric area portion is:
d ni ＝R n1 -R′ nri
wherein R 'is' nri The equivalent outer diameter of the permanent magnet of each region, R, being a non-concentric region portion n1 Is the outer diameter of the non-concentric portion.
6. The method for optimizing eddy current loss of a permanent magnet according to claim 1, wherein:
in step 2), the permanent magnet eddy current loss pattern of the non-concentric pole permanent magnet motor includes a concentric pole region and a permanent magnet eddy current loss pattern of the non-concentric pole region.
7. The method for optimizing eddy current loss of a permanent magnet according to claim 6, wherein:
the permanent magnet eddy current loss model of the concentric magnetic pole region is:
Figure FDA0004100325670000031
wherein J is III ，H III Respectively the followingThe current density and the magnetic field intensity in the region, L is the axial length of the permanent magnet, R 1 Is the outer diameter of the concentric portion of the permanent magnet.
8. The method for optimizing eddy current loss of a permanent magnet according to claim 6, wherein:
the permanent magnet eddy current loss model of the non-concentric magnetic pole region is:
Figure FDA0004100325670000032
wherein the permanent magnet loss of each circumferential region is:
Figure FDA0004100325670000033
wherein the method comprises the steps of
Figure FDA0004100325670000041
Wherein P is II Is the eddy current loss average value; p (P) iII Is of intermediate quantity, mu 0 Is vacuum magnetic permeability; mu (mu) pm Is the magnetic permeability of the permanent magnet; l is the length of the iron core; t is the period of the motor; alpha p Is the polar arc coefficient of the permanent magnet; k is the number of circumferential partitions of the non-concentric region; sigma (sigma) pm Is the conductivity of the permanent magnet; n is n 1 Is the rotation speed; n is the number of magnetic field space harmonics; m is the current time harmonic frequency; r's' pmi Equivalent radius for each region; r is R s Is the inner diameter of the stator; r is R r Is the inner diameter of a non-concentric magnetic pole; j (J) mn Harmonic amplitude values of equivalent current sheets distributed on the inner diameter of the stator; τ pm Is the skin depth of the permanent magnet; y is Y m Is a Norman function; y is Y m ' is the first derivative of the Neumann function; j (J) m As a Bessel function; j (J) m ' is the first derivative of the Bessel function; p is the pole pair number of the motor; omega r Is the rotor angular velocity; θIs the circumferential angle in the static coordinate system;
Figure FDA0004100325670000042
an initial phase for stator winding current; j is an imaginary unit; l is the number of magnetic permeability harmonics; k (k) δ Is the air gap coefficient; z is the number of stator slots; c (C) 1 Is of intermediate quantity, C 1 * Is C 1 Is a complex conjugate of (a) and (b).
9. The method for optimizing eddy current loss of a permanent magnet according to claim 1, wherein: in the step 3), the loss in the permanent magnet eddy current loss model is minimum, namely, the permanent magnet eddy current loss model is derived.
10. The method for optimizing eddy current loss of a permanent magnet according to claim 1, wherein: in step 3), the eccentricity h is:
Figure FDA0004100325670000043
wherein R is r The inner diameter of the permanent magnet is chamfered for the outer pole arc, d is the thickness of the center of the permanent magnet, alpha p Is the polar arc coefficient of the permanent magnet.
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