CN111245118A - Unequal tooth width combined permanent magnet synchronous motor and electromagnetic vibration weakening method thereof - Google Patents
Unequal tooth width combined permanent magnet synchronous motor and electromagnetic vibration weakening method thereof Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/12—Stationary parts of the magnetic circuit
- H02K1/16—Stator cores with slots for windings
- H02K1/165—Shape, form or location of the slots
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
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- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
- H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
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- H—ELECTRICITY
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Abstract
The invention discloses a combined permanent magnet synchronous motor with unequal tooth widths and an electromagnetic vibration weakening method thereof, wherein a stator, a permanent magnet rotor and an armature winding are sleeved in the stator and are coaxially arranged with the stator; the stator comprises stator slots, stator teeth and a stator yoke, the stator yoke is annular, the stator teeth are uniformly distributed along the circumference of the stator yoke, the stator slots are arranged among the stator teeth, and armature windings are placed in the stator slots; the width of at least one of the stator teeth is different from the widths of other stator teeth, and the widths of other stator teeth are the same. The cogging torque and the tooth harmonic electromotive force of the permanent magnet motor are greatly reduced by adopting the mode of the stator with the unequal tooth width combined structure, so that the motor can have smaller torque pulsation; the torque pulsation weakening effect equivalent to that of a stator skewed slot can be achieved by changing the width of the motor stator teeth, and the method of replacing the stator skewed slot or rotor skewed pole in industry to weaken the torque pulsation is replaced.
Description
Technical Field
The disclosure relates to the technical field of weakening electromagnetic vibration of permanent magnet synchronous motors, in particular to a permanent magnet synchronous motor with unequal tooth width combination and an electromagnetic vibration weakening method thereof.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In recent years, with the improvement of high temperature resistance and the reduction of price of permanent magnet materials, permanent magnet motors are widely applied in national defense, industry, agriculture and daily life, and are developing towards high power, high functionality and miniaturization, and the variety and application field of the permanent magnet motors are continuously expanded. At present, the power of the permanent magnet motor ranges from several milliwatts to several kilowatts, the application range is from small to toy motors and large to large permanent magnet motors used for ship traction, and the permanent magnet motor is widely applied to various aspects of national economy, daily life, military industry and aerospace.
Compared with other motors, the permanent magnet synchronous motor has the characteristics of simple structure, higher output torque density and higher efficiency. The permanent magnet motor with superior performance can meet the higher requirement of a servo system on the motor, the torque pulsation of the motor can generate great influence on the precision of the servo system, and when the pulsation frequency and the stator and the rotor resonate, the motor can generate great vibration noise to influence the normal operation of the system. The large torque ripple is a prominent disadvantage of the permanent magnet motor, and needs to be weakened by taking certain measures. Torque ripple is caused by a variety of reasons, including factors in the control strategy and imperfections in the design of the motor body.
Compared with the traditional induction motor, the permanent magnet motor has more output than the cogging torque caused by the permanent magnet, and the cogging torque is reduced as much as possible by taking the factor into consideration when the motor is designed. The final output instantaneous torque of the permanent magnet machine includes the fundamental electromagnetic torque and the cogging torque. The existence of the cogging torque can increase the torque pulsation of the permanent magnet motor, and is not beneficial to the application of the motor to high-precision control occasions.
At present, the cogging torque and the tooth harmonic electromotive force of the permanent magnet motor are weakened by mainly adopting a stator skewed slot or a rotor skewed pole in the industry, so that the aim of weakening the torque pulsation is fulfilled, but the difficulty and the cost of industrial manufacturing are increased by adopting a skewed pole or a skewed slot mode, and the method is difficult to realize when the axial length of the motor is short.
Disclosure of Invention
In order to solve the problems, the invention provides an unequal tooth width combined permanent magnet synchronous motor and an electromagnetic vibration weakening method thereof, and the motor disclosed by the invention greatly reduces the cogging torque and the tooth harmonic electromotive force of the permanent magnet motor by adopting a stator with an unequal tooth width combined structure, so that the motor can have smaller torque pulsation; the torque pulsation weakening effect equivalent to that of a stator chute can be achieved by changing the width of the motor stator teeth, and the torque pulsation weakening method can be used for weakening the torque pulsation instead of the stator chute or the rotor oblique pole in the industry.
In order to achieve the purpose, the following technical scheme is adopted in the disclosure:
in a first aspect, the present disclosure provides a combined permanent magnet synchronous motor with unequal tooth widths, comprising: the permanent magnet rotor is sleeved inside the stator and is coaxially arranged with the stator;
the stator comprises stator slots, stator teeth and a stator yoke, the stator yoke is annular, the stator teeth are uniformly distributed along the circumference of the stator yoke, the stator slots are arranged among the stator teeth, and armature windings are placed in the stator slots; the width of at least one of the stator teeth is different from the widths of other stator teeth, and the widths of other stator teeth are the same.
As some possible implementations, the stator teeth include wide stator teeth and narrow stator teeth, there is at least one wide stator tooth having a width greater than the width of the other narrow stator teeth, varying the number of wide stator teeth and the tooth width ratio of the narrow stator teeth and the wide stator teeth reduces the cogging torque of the permanent magnet machine, and the sum of the widths of all the stator teeth is constant.
As some possible implementations, the number of the wide stator teeth satisfies that the number of the wide stator teeth is a submultiple of the number of the stator slots.
As some possible implementations, when the number of wide stator teeth satisfies that the number of wide stator teeth is a divisor of the number of poles of the motor, in this case, it is necessary to exclude the number of wide stator teeth in which the distribution of the stator teeth has a large influence on the cogging torque.
As some possible implementation manners, when the number of the wide stator teeth is determined, the tooth width ratio of the narrow stator teeth and the wide stator teeth is changed so that Gn＝0，GnThe stator teeth distribution is the effect on cogging torque.
In a second aspect, the present disclosure provides a method for weakening electromagnetic vibration of a permanent magnet synchronous motor with unequal tooth widths, including:
the stator teeth are set to be of two different widths, namely wide stator teeth and narrow stator teeth, the width of at least one wide stator tooth is different from the widths of other narrow stator teeth, and the widths of the other narrow stator teeth are the same;
and the tooth space torque of the permanent magnet motor is reduced by changing the number of the wide stator teeth and the tooth width ratio of the narrow stator teeth and the wide stator teeth according to the design rule of the number of the wide stator teeth, and the sum of the widths of all the stator teeth is kept unchanged.
As some possible implementation manners, the design rule of the unequal tooth width combined permanent magnet synchronous motor is as follows: the number of the wide stator teeth meets the requirement that the number of the wide stator teeth is a divisor of the number of the stator slots; if the number of the wide stator teeth meets the requirement that the number of the wide stator teeth is a divisor of the number of poles of the motor, the number of the wide stator teeth with the largest influence on the cogging torque caused by the distribution of the stator teeth needs to be eliminated under the condition; when the number of the wide stator teeth is determined, the tooth width ratio of the narrow stator teeth and the wide stator teeth is changed to enable Gn＝0，GnThe stator teeth distribution is the effect on cogging torque.
As some possible realization modes, the circumferential angle corresponding to the wide stator tooth is set to be thetaaThe circumferential angle corresponding to other narrow stator teeth is thetab，KtFor the ratio of the narrow stator tooth width to the wide stator tooth width, the cogging torque expression is calculated by analysis as follows:
wherein G isnIs the influence of the distribution of the stator teeth on the cogging torque, BrnIs the influence of the distribution of rotor magnetic poles on the cogging torque, z is the number of stator slots, LaIs the length of the stator core, R2And R1Is the stator diameter and the rotor outer diameter, n is the harmonic number, when GnWhen 0, theoretically TcogIs 0, α is constantRelative position angle of rotor, mu0Is a vacuum magnetic permeability.
As some implementations are possible, with the number of wide stator teeth and the ratio K of the narrow stator tooth width to the wide stator tooth widthtChange of value of GnVarying therewith by selecting the ratio K of the width of the narrow stator teeth to the width of the wide stator teethtA value of (A) to G n0, thereby weakening the cogging torque of the permanent magnet motor, and the width theta of the stator teethaAnd thetabBy KtIs determined by the selection of (a).
As some possible implementations, permanent magnets are disposed on the permanent magnet rotor to form magnetic poles, and magnetic flux on the permanent magnet rotor enters the stator along an air gap between the stator and the rotor of the motor to form main magnetic flux, and the main magnetic flux acts with a magnetic field generated by an armature winding on the stator to enable the motor to generate torque.
Compared with the prior art, the beneficial effect of this disclosure is:
1. the motor stator disclosed by the invention is of a straight slot structure, and compared with the method for weakening the stator skewed slot commonly used in the tooth slot in the current industry, the processing cost is low, the processing technology is simple, the motor manufacturing efficiency can be effectively increased, and the motor manufacturing cost can be reduced. The suppression of the torque ripple of the permanent magnet motor under the non-oblique pole chute is achieved.
2. Compared with the traditional torque pulsation weakening method (stator chute or rotor oblique pole), the motor has the advantages that the permanent magnet consumption and the power density are the same, the power density is not reduced or the permanent magnet consumption is not increased, the consumption of ferromagnetic materials and permanent magnet materials is the same as that of the traditional motor, and the motor cost is not increased.
3. The stator of the motor is of a straight slot structure, and compared with a chute stator commonly used in the industry at present, the stator does not bring extra axial force, the axial force of the motor is equivalent to that of a traditional straight slot motor, and the electromagnetic vibration caused by the axial force of the motor can be further reduced.
4. Different from the existing unequal tooth width pairing (Teeth pairing), after the unequal tooth width method disclosed by the invention is adopted, the adjacent tooth pitches of the motors are changed and are not equal any more, so that the method has a remarkable weakening effect on each phase of integer slot and fractional slot motor of each pole, and can be suitable for the situation that the minimum n of each phase of integer slot motor with nz/(4p) is an odd number and an even number, while the existing unequal tooth width pairing (Teeth pairing) can not weaken the cogging torque and the tooth harmonic electromotive force of each phase of integer slot motor with nz/(4p) is an even number, and can only be suitable for the motor of which the minimum n of each phase of integer slot motor with nz/(4p) is an even number.
5. After the unequal tooth width method is adopted, the ratio of the total tooth width to the tooth pitch of the motor is kept unchanged, and the width of the notch of the motor is not changed compared with the prior art, so that the lower line of the motor winding is not influenced after the method is adopted.
6. After the unequal tooth width method is adopted, the number of wide teeth is reasonably selected through calculation, unbalanced magnetic tension of the motor can be avoided, and vibration and noise of the motor are inhibited.
7. The method for weakening the cogging torque of the motor is realized by combining unequal tooth widths, and compared with the traditional magnetic pole segmented motor, the method has the advantage that the effect of weakening the cogging torque is better. The weakening degree of the traditional magnetic pole segmented motor to the cogging torque is related to the number of the segments of the rotor, and the cogging torque of the permanent magnet motor cannot be completely eliminated theoretically; the motor can theoretically completely eliminate the cogging torque of the permanent magnet motor by a method of unequal tooth width combination, and the weakening effect of the cogging torque of the motor is superior to that of the traditional magnetic pole segmented motor.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a schematic structural diagram of a variable tooth width combined double-wide tooth surface-mounted permanent magnet synchronous motor according to the present disclosure;
fig. 2 is a schematic structural diagram of a variable tooth width combined six-wide tooth surface-mounted permanent magnet synchronous motor according to the present disclosure;
FIG. 3 is a schematic structural diagram of a variable tooth width combined dual-wide tooth interior permanent magnet synchronous motor according to the present disclosure;
FIG. 4 is a schematic structural diagram of a variable tooth width combined six-wide tooth interior permanent magnet synchronous motor according to the present disclosure;
fig. 5 is a view illustrating a form of a stator of a combined motor with unequal tooth widths according to the present disclosure, in which (a) is a stator of a conventional motor, (b) is a stator using a method of combining two wide teeth with unequal tooth widths, and (c) is a stator using a method of combining six wide teeth with unequal tooth widths;
FIG. 6 is a schematic structural diagram of a variable tooth width combined double-width tooth motor according to the present disclosure, which employs a first winding method;
FIG. 7 is a schematic structural diagram of a variable tooth width combined double-width tooth motor according to the present disclosure, which employs a second winding method;
FIG. 8 is a comparison of the low-order Gn results for a combined stator with unequal tooth widths using two wide teeth, four wide teeth, and eight wide teeth;
FIG. 9 is a comparison of cogging torque results for a conventional straight slot/skewed slot permanent magnet motor and the double and six wide tooth motors of the present disclosure;
FIG. 10 is a comparison of unbalanced radial magnetic pull force results for a conventional straight slot/skewed slot permanent magnet motor and the double wide tooth and six wide tooth motors of the present disclosure;
FIG. 11 is a comparison of back EMF results for a conventional straight slot/skewed slot permanent magnet motor and the double and six wide tooth motors of the present disclosure;
FIG. 12 is a comparison of dynamic output torque results for a conventional straight slot/skewed slot permanent magnet motor and the double wide tooth and six wide tooth motors of the present disclosure;
in the figure, 1, stator, 2, stator yoke, 3, stator teeth, 4, armature winding, 5, permanent magnet, 6, rotor core, 7, stator teeth with different widths, and 8, other stator teeth with the same width.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example 1
The disclosure relates to a permanent magnet synchronous motor electromagnetic vibration weakening method, in particular to a permanent magnet synchronous motor electromagnetic vibration weakening method with unequal tooth widths. The motor comprises a stator, a permanent magnet rotor and an armature winding. The structure of the stator is different from that of a conventional permanent magnet synchronous motor stator. The novel stator is of an unequal tooth width combined structure, the width of all the grooves on the stator is the same, the sum of the width of all the teeth of the stator is kept unchanged, the total groove area of all the grooves of the stator is kept unchanged, and the width of one tooth or a plurality of teeth in the teeth of the stator is changed to enable the width of the teeth to be different from the width of other teeth.
The cogging torque, the tooth harmonic electromotive force and the torque ripple of the permanent magnet motor can be greatly weakened through the mode of unequal tooth width combination, so that the electromagnetic vibration of the permanent magnet motor is effectively weakened; by reasonably selecting the mode of unequal tooth width combination, the flux linkage generated by the permanent magnet on the rotor can keep symmetry on the stator, and compared with the existing methods for weakening the cogging torque by some asymmetric structures, the method can eliminate the unbalanced radial magnetic tension caused by the asymmetry of the stator and further reduce the electromagnetic vibration when the motor runs;
the motor and the method thereof avoid the axial unbalanced magnetic pull force generated by the traditional skewed pole and chute process, can keep the use amount of the permanent magnet material unchanged, and realize weakening of the cogging torque and the electromagnetic vibration of the motor under the condition of not reducing the effective magnetic flux of each pole of the motor.
In particular to a combined permanent magnet synchronous motor with unequal tooth widths, which comprises a stator 1, a permanent magnet rotor and an armature winding 4, wherein the permanent magnet rotor comprises a rotor core and a permanent magnet 5, the rotor is sleeved in the stator and is coaxially arranged with the stator, the armature winding 4 is arranged on the stator,
the stator is of an unequal tooth width combined structure and comprises stator slots, stator teeth 3 and a stator yoke 2, wherein the stator yoke 2 is annular, the stator teeth 3 are uniformly distributed along the circumference of the stator yoke, the stator slots are arranged among the stator teeth 3, and armature windings are placed in the stator slots; the width of at least one stator tooth 7 in the stator teeth is different from the widths of other stator teeth 8, and the widths of the other stator teeth are the same.
The widths of all stator slots are the same, the sum of the widths of all stator teeth is kept constant, the total slot area of all stator slots is kept constant, and the widths of one tooth or a plurality of teeth in the stator teeth are changed to be different from the widths of other teeth.
By adopting the method for weakening the electromagnetic vibration of the unequal tooth width combined permanent magnet synchronous motor, the limiting factors to be considered comprise: the number of the wide teeth is single or multiple, whether the number of the wide teeth is the divisor of the number of the grooves or not, whether the number of the wide teeth is the integral multiple of the number of the poles or not and whether the number of the wide teeth is the divisor of the number of the poles or not.
When the number of the wide teeth is plural, the number of the wide teeth is divided into two cases of a divisor of the number of the slots and a divisor where the number of the wide teeth is not the number of the slots: if the number of the wide teeth is not the divisor of the number of the slots, the tooth space structure of the motor is asymmetric, unbalanced magnetic pull force is generated by the motor, vibration and noise are aggravated, and therefore the scheme that the number of the wide teeth is the divisor of the number of the slots is selected.
The design determination process of the combined permanent magnet synchronous motor with unequal tooth widths comprises the following steps: (1) the partially wide tooth number scheme is an asymmetric structure, which causes large unbalanced magnetic pull force, and the schemes should be excluded.
(2) For a scheme with a wide number of teeth being an integer multiple of the number of poles, the scheme would introduce G of 2np timesnActing with the air gap field to increase cogging torque, such wide tooth count schemes should be eliminated.
(3) For a wide tooth count that is a divisor of a pole number, this type of scheme would introduce G of 2np ordersnSuch a wide tooth count scheme should be compared to an air gap field to increase cogging torque, excluding GnLarger wide teeth count schemes.
(4) Determining G corresponding to motor with residual wide tooth numbernWhen a wide-teeth-number scheme is used, K is changedtWhen the value of (A) is GnThis wide tooth count is excluded when it is not possible to converge to 0 simultaneously.
(5) And (4) carrying out finite element calculation analysis on the cogging torque of the motor on the rest schemes, and finally solving 1-2 schemes.
(6) For the design scheme of the permanent magnet synchronous motor with partially unequal tooth widths, different winding methods can affect the performance of the motor, and the different winding methods need to be analyzed to determine the optimal scheme.
Taking an 8-pole 48-slot permanent magnet synchronous motor as an example, the number of poles of the motor is 8, and the submultiples of the number of slots 48 of the motor are 1, 2, 3, 4, 6, 8, 12, 16 and 24, and the number of wide teeth of the motor can be selected from the 9 schemes. The two schemes of the number 1 of the wide teeth and the number 3 of the wide teeth are in asymmetric structures, so that large unbalanced magnetic tension exists and the large unbalanced magnetic tension is to be eliminated;
wherein, the number of the wide teeth 8, 16 and 24 is integral multiple of the number of the poles 8 of the motor, and the schemes are excluded;
wherein the wide teeth number 2 and 4 is the submultiple of the motor pole number 8, the two schemes are compared, and when the wide teeth number 4 is adopted, a larger lower G order is introducednSuch a scheme should be excluded;
calculated when the number of the wide teeth is 12GnThe inability to converge to 0 at the same time, such a solution should be excluded;
finite element calculation is carried out on the two schemes of 2 and 6 of the number of the wide teeth, and the cogging torques of the two schemes are close; finally the motor stator can be selected to have a wide number of teeth of 2 and 6. The motor with 2 wide teeth number has 6 winding methods, and needs to be analyzed and calculated to determine the optimal winding mode.
The following is an analytical calculation procedure for cogging torque:
first, looking from the axial direction, determiningThe teeth of the sub-teeth have two different widths, and the circumferential angle corresponding to the wide teeth is set as thetaaThe circumferential angle corresponding to other teeth is thetab，θaAnd thetabThe selection follows the following principle:
cogging torque is defined as the negative derivative of the magnetic field energy W when the motor is not energized to the stator and rotor relative position angle α, i.e.:
wherein
Wherein mu0For vacuum permeability, α is the relative position of the stator and rotor, and the air gap distribution B (θ, α) along the armature surface can be expressed as:
wherein B isr(theta) is the remanence of the permanent magnet, hm(theta) is the permanent magnet charging direction length, and delta (theta, α) is the effective air gap length, thus
Wherein the content of the first and second substances,
the fourier expansion of (a) can be expressed as:
while
The fourier expansion of (a) can be expressed as:
the expression for cogging torque can be expressed as:
wherein G isnIs the influence of the tooth distribution on the cogging torque, BrnIs the influence of the distribution of rotor magnetic poles on the cogging torque, z is the number of stator slots, LaIs the length of the stator core, R2And R1Is the stator diameter and the rotor outer diameter, n is the harmonic number, when GnWhen 0, theoretically TcogIs 0.
With the number of wide teeth and the ratio of narrow teeth to wide teeth KtChange of value of GnVarying therewith by selecting the ratio K of narrow teeth to wide teethtCan be given a value of G n0, so as to effectively weaken the cogging torque of the permanent magnet motor, therefore, the width theta of the stator teethaAnd thetabCan be prepared by reacting at GnIn the expanded form of (K)tIs determined.
Meanwhile, the width of the stator teeth is changed, so that the number of the grooves corresponding to each magnetic pole is changed, and K is usedtThe number of slots corresponding to each magnetic pole of the motor is a fraction, so that the number of slots occupied by each phase belt under each magnetic pole is different, each coil group is positioned at different positions under the magnetic poles, the harmonic electromotive forces in the coils are different in phase, and when the harmonic electromotive forces vectors of the teeth of each coil are added together, most of the harmonic electromotive forces are offset, so that the tooth harmonic electromotive forces in the windings can be greatly weakened under the unequal tooth width combined structure.
For the combined permanent magnet synchronous motor with unequal tooth widths, because the windings are unevenly distributed, the forward rotating magnetomotive forces cannot be directly added, and the reverse rotating magnetomotive forces cannot be mutually offset; the reduction of the forward rotational magnetomotive force reduces the output torque of the motor, and the presence of the reverse rotational magnetomotive force increases the torque ripple of the motor. By reasonably selecting the winding mode, the reduction of the forward rotating magnetomotive force and the increase of the reverse rotating magnetomotive force can be avoided as much as possible.
The combined permanent magnet synchronous motor with unequal tooth widths is asymmetrical if symmetrical three-phase current is introduced into an asymmetrical three-phase windingThe three-phase windings of (A) are spatially mutually different in electrical angle and KtRelated when KtWhen the mutual differential electrical angle of the three-phase windings is not 120 degrees, the mutual differential electrical angle of fundamental wave magnetomotive force generated by the three-phase windings is not 120 degrees;
when the motor is in an operating state, the introduced current is three-phase symmetrical current, the three-phase current introduced into the three-phase winding is symmetrical, the phase difference of the three-phase current is 120 degrees, and the amplitude is equal.
The current expression is:
the fundamental magnetomotive force generated by these three currents is a pulsed magnetomotive force that is temporally 120 degrees out of electrical angle with respect to each other. If the space coordinate thetasThe origin of (b) is taken on the axis of the winding of the a phase, and the instant at which the a phase current reaches the maximum value is taken as the time starting point, the expression of the fundamental wave of the pulsating magnetomotive force generated by the A, B, C three-phase winding is as follows:
fA1＝Fφ1cos(θs)cos(wt)
fB1＝Fφ1cos(θs-2π/3+θs1)cos(wt-2π/3)
fC1＝Fφ1cos(θs-4π/3+θs2)cos(wt-4π/3)
wherein, thetas1And thetas2The angle of the axes of the windings of the B phase and the C phase is the angle when the windings of the B phase and the C phase deviate from the symmetry of the three-phase winding;
according to the formula cos α cos β ═ cos (α - β) + cos (α + β) ]/2, three pulse-oscillation magnetomotive forces can be decomposed into:
the first term on the right side in the above formula is a forward rotating magnetomotive force, and the second term is a reverse rotating magnetomotive force. The rotation speed of the two is the same, and the rotation directions are opposite. The amplitude of each rotational magnetomotive force is half of the amplitude of the pulse-vibration magnetomotive force. As can be seen from the above equation, the forward rotary magnetomotive forces generated by the respective phase currents are spatially different in phase, and the reverse rotary magnetomotive forces are spatially different from each other by 120 degrees.
When the synthetic magnetomotive force is obtained, the forward rotating magnetomotive force cannot be directly added, the reverse rotating magnetomotive force cannot be mutually offset, and the three-phase fundamental wave synthetic magnetomotive force is as follows:
f1(θs,t)＝fA1+fB1+fC1
the three-phase fundamental wave synthesized forward rotating magnetomotive force is as follows:
the three-phase fundamental wave synthesized reverse rotating magnetomotive force is as follows:
when the motor stator is of an unequal tooth width combined structure, the motor winding is a three-phase asymmetric winding, and when the synthetic magnetomotive force is solved, the forward rotating magnetomotive force can be subjected to vector addition, and the reverse rotating magnetomotive force can be subjected to vector addition.
In the design process of the unequal tooth width combined permanent magnet synchronous motor, the forward rotating magnetomotive force is increased as much as possible, and the reverse rotating magnetomotive force is reduced, so that the torque pulsation of the motor is reduced. When the number of the wide teeth of the unequal tooth width combined permanent magnet synchronous motor is determined, the forward rotating magnetomotive force can be improved by changing the winding mode of the stator winding.
The structure of the motor disclosed by the present invention is shown in fig. 1 to 4, wherein the motor comprises a stator, a permanent magnet rotor and an armature winding, wherein the stator is provided with stator slots, the armature winding is placed in the stator slots, the rotor and the stator are concentrically arranged, the rotor is provided with permanent magnets, and the stator core has a structure of double-width teeth with unequal tooth width combinations and six-width teeth with unequal tooth width combinations, which are different from the stator core of a traditional motor.
The combined stator teeth of the double-width motor with unequal tooth widths have different widths, as shown in fig. 5(b), wherein two teeth have a width θaWidth theta with other 46 teethbIn contrast, set Kt＝θb/θaThe ratio of the narrow teeth to the wide teeth is GnK when equal to 0tThe value is related to the tooth width to slot width ratio of the conventional motor stator in fig. 5(a) such that GnK equal to 0tSelecting K from the valuestValue, determining the width theta of the wide toothaAnd width theta of narrow toothb。
The permanent magnet of the motor generates magnetic flux, the magnetic flux enters the stator along the air gap between the stator and the rotor of the motor to form main magnetic flux, and the main magnetic flux of the rotor and a magnetic field generated by the armature winding of the stator interact to generate torque. For the permanent magnet synchronous motor with unequal tooth width combined double-width tooth structure, compared with the two winding methods in fig. 6 and 7, the winding method in fig. 6 has larger forward rotating magnetomotive force and better torque performance.
The stator teeth of the combined six-width tooth motor with different tooth widths have different widths, as shown in fig. 5(c), wherein the width of six teeth is thetaaWidth theta with other 42 teethbIn contrast, set Kt＝θb/θaThe ratio of the narrow teeth to the wide teeth is GnK when equal to 0tThe value is related to the tooth width to slot width ratio of the conventional motor stator in fig. 5(a) such that GnK equal to 0tSelecting K from the valuestValue, determining the width theta of the wide toothaAnd width theta of narrow toothb。
The permanent magnet of the motor generates magnetic flux, the magnetic flux enters the stator along the air gap between the stator and the rotor of the motor to form main magnetic flux, and the main magnetic flux of the rotor and a magnetic field generated by the armature winding of the stator interact to generate torque. When the stator structure is adopted for the permanent magnet synchronous motor with the unequal tooth width combined six-width tooth structure, only one winding method is adopted.
The motors provided by the present disclosure can be used in many ways, and the following are now briefly exemplified:
(1) household appliances: including television audio and video equipment, fans, air-conditioning external hanging machines, food processing machines, smoke exhaust ventilators and the like.
(2) Computer and its peripheral equipment: including computers (drives, fans, etc.), printers, plotters, optical drives, optical disc recorders, scanners, etc.
(3) Industrial production: including industrial drives, material processing systems, automation equipment, robots, transmission systems, and the like.
(4) The automobile industry: the system comprises a permanent magnet starter, a windscreen wiper motor, a door lock motor, a seat lifting motor, a sunshade ceiling motor, a cleaning pump motor, a motor for a recorder, a glass lifting motor, a radiator cooling fan motor, an air conditioner motor, an antenna lifting motor, an oil pump motor, a rearview mirror adjustment and the like.
(5) The field of public life: including clocks, beauty machines, vending machines, cash dispensers, cash registers, etc.
(6) The field of transportation: including trolleybuses, aircraft accessories, ships, and the like.
(7) The aerospace field: including rockets, satellites, spacecraft, space shuttles, and the like.
(8) The national defense field: including tanks, missiles, submarines, planes, etc.
(9) The medical field is as follows: including dental burs, artificial hearts, medical instruments, and the like.
(10) The field of power generation: the system comprises a generator for wind power generation, waste heat power generation, small hydroelectric power generation, a small internal combustion generator set, an auxiliary exciter of a large generator and the like.
(11) Novel pure electric vehicles field: under the current great trend that the environmental protection and energy problems are concerned, in order to solve the defects that the traditional automobile pollutes the environment and uses non-renewable energy, the electric automobile has the trend of accelerating development; meanwhile, the electric automobile is easy to realize intellectualization, and the improvement of the safety and the service performance of the automobile are facilitated. The electric automobile has the requirements of good torque control capability, high torque density, reliable operation, large speed regulation range and the like for a driving system of the electric automobile.
The above is merely a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, which may be variously modified and varied by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (10)
1. The utility model provides a tooth width combination PMSM that varies which characterized in that includes: the permanent magnet rotor is sleeved inside the stator and is coaxially arranged with the stator;
the stator comprises stator slots, stator teeth and a stator yoke, the stator yoke is annular, the stator teeth are uniformly distributed along the circumference of the stator yoke, the stator slots are arranged among the stator teeth, and armature windings are placed in the stator slots; the width of at least one of the stator teeth is different from the widths of other stator teeth, and the widths of other stator teeth are the same.
2. The unequal tooth width combined permanent magnet synchronous machine of claim 1,
the stator teeth comprise wide stator teeth and narrow stator teeth, the width of at least one wide stator tooth is larger than the widths of other narrow stator teeth, the cogging torque of the permanent magnet motor is reduced by changing the number of the wide stator teeth and the tooth width ratio of the narrow stator teeth to the wide stator teeth, and the sum of the widths of all the stator teeth is unchanged.
3. The unequal tooth width combined permanent magnet synchronous machine of claim 2,
the number of the wide stator teeth meets the requirement that the number of the wide stator teeth is a divisor of the number of the stator slots.
4. The unequal tooth width combined permanent magnet synchronous machine of claim 3,
and the number of the wide stator teeth meets the condition that the number of the wide stator teeth is a divisor of the number of poles of the motor, and the number of the wide stator teeth with the largest influence on the cogging torque caused by the distribution of the stator teeth needs to be eliminated.
5. The unequal tooth width combined permanent magnet synchronous machine of claim 4,
when the number of the wide stator teeth is determined, the tooth width ratio of the narrow stator teeth and the wide stator teeth is changed to enable Gn＝0，GnThe stator teeth distribution is the effect on cogging torque.
6. A method for weakening electromagnetic vibration of a combined permanent magnet synchronous motor with unequal tooth widths is characterized by comprising the following steps:
the stator teeth are set to be of two different widths, namely wide stator teeth and narrow stator teeth, the width of at least one wide stator tooth is different from the widths of other narrow stator teeth, and the widths of the other narrow stator teeth are the same;
and the tooth space torque of the permanent magnet motor is reduced by changing the number of the wide stator teeth and the tooth width ratio of the narrow stator teeth and the wide stator teeth according to the design rule of the number of the wide stator teeth, and the sum of the widths of all the stator teeth is kept unchanged.
7. The method for attenuating electromagnetic vibration of a variable tooth width combined PMSM according to claim 6,
the number of the wide stator teeth meets the requirement that the number of the wide stator teeth is a divisor of the number of the stator slots; under the condition that the number of the wide stator teeth is the divisor of the number of poles of the motor, the number of the wide stator teeth which have the largest influence on the cogging torque due to the distribution of the stator teeth needs to be eliminated; when the number of the wide stator teeth is determined, the tooth width ratio of the narrow stator teeth and the wide stator teeth is changed to enable Gn＝0，GnThe stator teeth distribution is the effect on cogging torque.
8. The method for attenuating electromagnetic vibration of a variable tooth width combined PMSM according to claim 6,
setting the corresponding circumferential angle of the wide stator teeth as thetaaThe circumferential angle corresponding to other narrow stator teeth is thetab，KtFor the ratio of the narrow stator tooth width to the wide stator tooth width, the cogging torque expression is calculated by analysis as follows:
wherein G isnIs the influence of the distribution of the stator teeth on the cogging torque, BrnIs the influence of the distribution of rotor magnetic poles on the cogging torque, z is the number of stator slots, LaIs the length of the stator core, R2And R1Is the stator diameter and the rotor outer diameter, n is the harmonic number, when GnWhen 0, theoretically Tcog0, α is the relative position angle of stator and rotor, mu0Is a vacuum magnetic permeability.
9. The method for attenuating electromagnetic vibration of a variable tooth width combined PMSM according to claim 8,
with the number of wide stator teeth and the ratio K of the width of the narrow stator teeth to the width of the wide stator teethtChange of value of GnVarying therewith by selecting the ratio K of the width of the narrow stator teeth to the width of the wide stator teethtA value of (A) to Gn0, thereby weakening the cogging torque of the permanent magnet motor, and the width theta of the stator teethaAnd thetabBy KtIs determined by the selection of (a).
10. The method for attenuating electromagnetic vibration of a variable tooth width combined PMSM according to claim 6,
the permanent magnet rotor is provided with permanent magnets to form magnetic poles, magnetic flux on the permanent magnet rotor enters the stator along an air gap between the stator and the rotor of the motor to form main magnetic flux, and the main magnetic flux acts with a magnetic field generated by an armature winding on the stator to enable the motor to generate torque.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112398253A (en) * | 2020-11-12 | 2021-02-23 | 国网江西省电力有限公司电力科学研究院 | Five-phase unequal tooth shoe double-harmonic permanent magnet synchronous motor and tooth shoe radian optimization method |
| CN112583148A (en) * | 2020-12-22 | 2021-03-30 | 哈尔滨理工大学 | Weaken stator structure of in-wheel motor tooth's socket torque |
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| US20080290751A1 (en) * | 2007-05-25 | 2008-11-27 | Chang-Chun Hwang | Brushless permanent magnet motor with unequal-width slots and method of producing the same |
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| US20080290751A1 (en) * | 2007-05-25 | 2008-11-27 | Chang-Chun Hwang | Brushless permanent magnet motor with unequal-width slots and method of producing the same |
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| 唐旭等: "基于改变定子齿槽参数的异步起动永磁同步电动机齿槽转矩削弱措施研究", 《电工技术学报》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112398253A (en) * | 2020-11-12 | 2021-02-23 | 国网江西省电力有限公司电力科学研究院 | Five-phase unequal tooth shoe double-harmonic permanent magnet synchronous motor and tooth shoe radian optimization method |
| CN112583148A (en) * | 2020-12-22 | 2021-03-30 | 哈尔滨理工大学 | Weaken stator structure of in-wheel motor tooth's socket torque |
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