JP3708855B2 - Synchronous motor with built-in permanent magnet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a synchronous motor with a built-in permanent magnet, in which a plurality of permanent magnets are built in a rotor core, and a rotor core having a magnetic salient pole portion between adjacent permanent magnets. The present invention relates to a synchronous motor with a built-in permanent magnet that uses a reluctance torque generated due to a salient pole portion and a torque generated by a permanent magnet.
[0002]
[Prior art]
In JP-A-8-205499, torque pulsation is provided by providing magnetic salient poles on the core between a plurality of permanent magnet magnetic poles mounted on the outer peripheral surface of a rotor core and shifting the positions of these salient poles in the circumferential direction. A synchronous motor that suppresses the occurrence of is disclosed. In this synchronous motor, the rotation direction of the rotor is limited to one direction.
[0003]
Japanese Patent Application Laid-Open No. 8-256455 discloses changing the magnetic pole width of the magnetic salient pole part of the rotor of the reluctance synchronous motor or shifting the positions of some pairs of magnetic salient pole parts in the circumferential direction. Thus, a technique for suppressing generation of pulsating torque of a reluctance synchronous motor is disclosed.
[0004]
In the conventional synchronous motor with a built-in permanent magnet disclosed in Japanese Patent Application Laid-Open No. 11-18328, the opening angle of the core between the permanent magnet magnetic poles is θ, and each of the end faces of the teeth corresponding to the width of the core between the permanent magnet magnetic poles The minimum value of the angle formed by two straight lines connecting the tip of the two most distant end faces and the rotation axis center is θmin and the most of each end of the tooth head in the tooth corresponding to the width of the core between the permanent magnet poles. When θmax is the maximum value of the angle formed by two straight lines connecting two separated ends and the rotation axis center,
θmin ≦ θ ≦ θmax
Thus, the width of the core between the permanent magnet magnetic poles is set so as to suppress the cogging torque.
[0005]
[Problems to be solved by the invention]
In the conventional permanent magnet built-in type synchronous motor, the opening angle θ of the core between the permanent magnet poles is set to θmin ≦ θ ≦ θmax determined from the number of teeth and the mold size. However, since the timing of torque generation between the permanent magnet magnetic poles differs according to the number of slots per phase per pole of the stator, this conventional technology cannot sufficiently suppress cogging torque and torque pulsation.
[0006]
An object of the present invention is to provide a permanent motor with a built-in permanent magnet that can suppress both cogging torque and torque pulsation during energization.
[0007]
[Means for Solving the Problems]
The present invention provides a stator in which a plurality of magnetic pole portions of a stator core are wound with one or more windings, and the number of pole pairs is p (where p is a positive integer of 1 or more), and the rotor core is fixed to a shaft. 2p permanent magnets are incorporated at intervals in the circumferential direction, 2p permanent magnet magnetic pole portions are formed on the outer periphery of the rotor core by the 2p permanent magnets, and the permanent magnet magnetic pole portions are sandwiched therebetween. A synchronous motor with a built-in permanent magnet including a rotor on which 2p magnetic salient poles are formed is an object of improvement. Here, one permanent magnet includes not only physically one permanent magnet but also a case where it is constituted by a plurality of permanent magnets and can be regarded magnetically as one permanent magnet. .
[0008]
In the present invention, 2p permanent magnet magnetic pole portions are arranged at equal intervals with the first permanent group p permanent magnet magnetic pole portions arranged at equal intervals in the circumferential direction. A second group of p permanent magnet magnetic pole portions is used. In addition, 2p magnetic salient pole portions are also arranged at equal intervals every other piece in the circumferential direction with p magnetic salient pole portions of the first group located at equal intervals in the circumferential direction. A second group of p magnetic salient poles. The opening angle α1 of the p magnetic salient pole portions of the first group is made smaller than the opening angle α2 of the p magnetic salient pole portions of the second group. Then, the opening angle α1 and the opening angle α2 are determined so as to satisfy the following expression.
[0009]
α2−α1≈2β− (2n−1) τs
Here, n is a natural number, β is an angle between two salient pole virtual center lines (CL1, CL2) passing through the centers of two magnetic salient poles adjacent from the center of the shaft, and τs is The slot pitch of the stator core [unit is rad]. The contour shape of the outer peripheral surface portion of the permanent magnet magnetic pole portion of the rotor core may be constituted by an arc or an elliptical arc.
[0010]
As described above, when the opening angle α1 of the p magnetic salient pole portions of the first group and the opening angle α2 of the p magnetic salient pole portions of the second group are determined, Compared with the conventional synchronous motor in which the opening angle of the 2p magnetic salient pole portions of the second group is constant, the torque pulsation can be suppressed and the torque ripple can be greatly reduced.
[0011]
In this case, the curvature radius R1 of the magnetic pole faces of the p magnetic salient pole portions of the first group is larger than the curvature radius R2 of the magnetic pole faces of the p magnetic salient pole portions of the second group. If it is made smaller, the torque ripple can be made smaller than when the radii of curvature R1 and R2 are made the same. In order to increase the torque, it is desirable that the curvature radii R1 and R2 are larger than the curvature radii of the end portions of the magnetic pole surfaces of the adjacent permanent magnet magnetic pole portions and that R1 <R2. However, in order to reduce the torque ripple at the expense of the magnitude of the torque, the curvature radii R1 and R2 may be smaller than the curvature radii of the end portions of the magnetic pole surfaces of the adjacent permanent magnet magnetic pole portions. Of course.
[0012]
In this case, the outer peripheral surface portion shape of the rotor core formed by the two adjacent permanent magnet magnetic pole portions and the magnetic salient pole portion positioned between the two adjacent permanent magnet magnetic pole portions is adjacent to the center of the shaft 2. It is symmetrical about the salient pole virtual center line (CL1, CL2) passing through the center of the magnetic salient pole located between the two permanent magnet magnetic poles, and the outer peripheral shape of the rotor core is circumferential. It is preferable to define the shapes of the 2p permanent magnet magnetic pole portions and the 2p magnetic salient pole portions so that the outer peripheral surface partial shapes in the angle range of 360 ° / p are all equal to each other. In this way, even when the opening angle of the magnetic salient pole is varied, the magnetic balance in the circumferential direction is balanced, so that no voltage imbalance or rotor eccentric force occurs in each phase.
[0013]
When the magnetic pole surface of the permanent magnet magnetic pole portion is formed by an arc surface or an elliptical arc surface, the dimension of the gap formed between the magnetic pole surface of the permanent magnet magnetic pole portion and the magnetic pole surfaces of the plurality of magnetic pole portions of the stator core It is preferable that δd is determined so as to satisfy or substantially satisfy the following expression.
[0014]
δd = δd0 / cos [p (θm−θdm)]
Here, δd0 is the minimum value of the gap dimension, and θm is two salient pole virtual centers passing through the center of the magnetic salient pole located between the two permanent magnet magnetic poles adjacent from the center of the shaft. This is an angle from the virtual center line CL3 passing through the center of the line (CL1, CL2) to the magnetic salient pole portion side having the opening angle α1. Θdm is an angle from the imaginary line PL3 to the imaginary center line CL3 at which the gap dimension is the minimum value.
[0015]
In the above formula, the gap when θdm = 0 ° forms a so-called general cosec gap. If such a gap configuration is adopted, the permanent magnet in the gap is used regardless of the rotation direction of the motor. Can be made close to a sine wave, and cogging torque can be suppressed.
[0016]
Here, θdm for minimizing the cogging torque is determined by the equation θdm≈ (ψ2-ψ1) / 2 when angles ψ1 and ψ2 described later are used. However, when the magnetic flux density distribution from the permanent magnets in the gap is greatly broken from the sine wave, the cogging torque is in the range of (1/6) × x × τs ≦ θdm ≦ (1/2) × xx × τs. There is a value that minimizes. Here, x is a natural number that makes θdm closest to the value of (ψ2−ψ1) / 2 when approximated as θdm≈ (ψ2−ψ1) / 2≈ (1/4) × x × τs.
[0017]
Furthermore, after satisfying the above conditions, the opening angle α2 of the virtual center line (CL3) and two virtual lines (PL1, PL2) passing from the center of the shaft to both ends in the circumferential direction of the magnetic pole surface of the permanent magnet magnetic pole portion. An angle ψ1 between an imaginary line (PL1) located on the magnetic salient pole part side having a diameter, and a virtual center line (CL3) passing through both ends in the circumferential direction of the magnetic pole surface of the permanent magnet magnetic pole part from the center of the shaft. The angle ψ2 between the two virtual lines (PL1, PL2) and the virtual line (PL2) located on the magnetic salient pole portion side having the open angle α1 satisfies the following conditional expression. .
[0018]
ψ2> ψ1
ψ2-ψ1 ≒ 0.5 (2m-1) τs- (180 ° / p)
ψ2 + ψ1 ≒ u ・ τs
α1 + α2 ≦ (360 ° / p) −2 (ψ2 + ψ1)
Here, m and u are arbitrary natural numbers. If this condition is satisfied, the cogging torque can be brought close to the minimum value, and torque ripple can also be suppressed.
[0019]
Even in a motor in which the gap dimension δd described above does not form a so-called cosec gap, the cogging torque and the torque ripple can be reduced by satisfying the relationship between the angles ψ2, ψ1 and the open angles α1, α2. Can do.
[0020]
Further, if α1 and α2 and ψ2 and ψ1 satisfy the following expression, the cogging torque can be brought close to the minimum value, and the torque ripple can also be brought close to the minimum value.
[0021]
(180 ° / 2p) + (α1 / 2) −ψ2≈ (1/4) (2v1-1) τs
(180 ° / 2p) + (α2 / 2) −ψ1≈ (1/4) (2v2-1) τs
Here, v1 and v2 are arbitrary natural numbers.
[0022]
When the first and second nonmagnetic portions are formed on the rotor core by air gaps on both sides in the circumferential direction of the permanent magnet, the first nonmagnetic portion is located on the side of the magnetic salient pole portion having an opening angle α1. When the second nonmagnetic portion is located on the side of the magnetic salient pole portion having an opening angle α2, the first and second nonmagnetic portions have the same cross-sectional area or second shape. It is preferable that the cross-sectional shape of the non-magnetic portion is larger than the cross-sectional shape of the first non-magnetic portion. Providing such a nonmagnetic portion can suppress leakage (short circuit) of magnetic flux from the permanent magnet and prevent demagnetization of the permanent magnet. However, since the opening angles α1 and α2 are made different in the present invention, the easiness of leakage of the magnetic flux of the permanent magnet and the easiness of demagnetization of the permanent magnet are different at both ends in the circumferential direction of the permanent magnet. That is, when α1 <α2, the leakage of magnetic flux from the end of the permanent magnet on the α2 side is larger than the leakage of magnetic flux from the end of the permanent magnet on the α1 side. Therefore, the amount of demagnetization at the end of the α2 side permanent magnet is larger than the amount of demagnetization at the end of the α1 side permanent magnet. From such a viewpoint, in order to positively suppress leakage of magnetic flux from the end of the permanent magnet on the α2 side and demagnetization at that portion, the cross-sectional area of the second nonmagnetic portion is set to the first nonmagnetic portion. It is larger than the cross-sectional area.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a stator and a rotor according to an embodiment of a synchronous motor with a built-in permanent magnet of the present invention. In FIG. 1, a member denoted by reference numeral 1 includes an annular yoke 2 formed by laminating silicon steel plates, and a magnetic pole portion disposed at a predetermined interval in the circumferential direction on the inner peripheral side of the annular yoke. A plurality of teeth 3, a slot 4 formed between two adjacent teeth 3, and a winding portion (not shown) formed by sequentially winding three-phase windings around these teeth 3. It is a stator provided with. The yoke 2 and the teeth 3 constitute a stator core.
[0024]
In the stator 1 of this example, the number of slots Ns is 48, the number of pole pairs p is 4, and the number of phases is 3, so the number of slots per phase per pole q is q = 48 / (2 × 4 × 3) = 2. The slot pitch τs is τs = 7.5 °.
[0025]
Moreover, the member shown with the code | symbol 5 is a rotor. The rotor 5 incorporates eight permanent magnets 8 arranged at intervals in the circumferential direction inside a rotor core 7 fixed to the shaft 6, and each of them is between two adjacent permanent magnets 8. It has magnetic salient poles 9... 10. A plurality of grooves 11 extending in the radial direction and the axial direction are formed on the outer peripheral portion of the rotor core 7 in order to clearly form the magnetic salient pole portions 9. The outer peripheral surface portion of the rotor core 7 located on the radially outer side of the permanent magnet 8 constitutes eight permanent magnet magnetic pole portions 12. The rotor core 7 is also configured by laminating silicon steel plates in the same manner as the stator core, and has a through hole into which a permanent magnet is inserted in a portion where the permanent magnets 8 are built. The permanent magnet 8 has a rectangular cross-sectional shape.
[0026]
In this example, the shape of the eight permanent magnet magnetic pole portions 12... And the eight magnetic salient pole portions 9... And 10 ... is between two adjacent permanent magnet magnetic pole portions and two adjacent permanent magnet magnetic pole portions. The shape of the outer peripheral surface portion of the rotor core 7 formed by the magnetic salient pole portion located at the center passes through the center of the magnetic salient pole portion located between the two permanent magnet magnetic pole portions adjacent from the center of the shaft 6. The salient pole virtual center lines CL1 and CL2 are centered about the line, and the outer peripheral surface shape of the rotor core 7 has a quadrangular shape in which all the outer peripheral surface portion shapes in the angular range of 90 ° are equal in the circumferential direction. It is stipulated in.
[0027]
Eight magnetic salient poles are arranged at equal intervals every other piece in the circumferential direction with four magnetic salient poles 9 of the first group located at equal intervals in the circumferential direction. It consists of four magnetic salient poles 10 of the second group located. The opening angle α1 of the four magnetic salient pole portions 9 of the first group is smaller than the opening angle α2 of the four magnetic salient pole portions 10 of the second group. In this example, since the slot pitch of the stator core 7 is 7.5 ° and the slot opening is 2.1 °, the opening angle α2 is 15 ° and the opening angle α1 is 7.5 °. In this case, a preferable range of the opening angle α2 is a value of 12.9 ° ≦ α2 ≦ 17.1 °, and a preferable range of the opening angle α1 is a value of 5.4 ° ≦ α1 ≦ 9.6 °. .
[0028]
If the relationship between the opening angle α1 and the opening angle α2 is generally expressed by an equation, both may be determined so as to satisfy the following equation (1).
[0029]
α2−α1≈ (2β) − (2n−1) τs (1)
Here, n is a natural number, β is an angle between two salient pole virtual center lines (CL1, CL2) passing through the centers of two magnetic salient poles adjacent from the center of the shaft, and τs Is the slot pitch of the stator core. In the present embodiment, n = 6. If this equation is satisfied, the torque ripple can be greatly reduced as compared with the conventional case.
[0030]
FIG. 2 is a diagram showing a configuration of a rotor used in a synchronous motor with a built-in permanent magnet according to a second embodiment of the present invention. This embodiment differs from the embodiment of FIG. 1 in that a pair of nonmagnetic portions 13 are provided in the rotor core 7 by gaps formed on both sides in the circumferential direction of the permanent magnets 8. Open angles α1 and α2 of the four magnetic salient pole portions 9... And the four magnetic salient pole portions 10... Are determined in the same manner as in the embodiment of FIG. The opening angle of the groove 11 can be obtained by an angle βd−α1, and is 1.875 ° in this example. The angle βd is determined by βd≈ (1/2) (2n−1) τs. Here, n is an arbitrary natural number.
[0031]
FIG. 3 is a diagram showing a configuration of a rotor of a synchronous motor with a built-in permanent magnet according to a third embodiment corresponding to the ninth aspect of the invention. This embodiment differs from the embodiment of FIG. 2 in that the opening angle (circumferential opening dimension) of the grooves 11 is larger than the opening angle of the grooves 11 of the embodiment of FIG. The length of the magnet magnetic pole 12 in the circumferential direction is reduced. The other structure is the same as that of the embodiment of FIG. In this embodiment, the opening angle (βf−α1) of the groove 11 is 3.75 °. Here, βf is determined by βf≈ (1/4) (2n−1) τs. Here, n is an arbitrary natural number.
[0032]
FIG. 4 is data obtained by measuring the torque ripple content rate for the embodiment of FIGS. 1 to 3. In FIG. 4, A is a torque ripple content rate of a conventional permanent magnet built-in type synchronous motor in which the open angles of the eight magnetic salient pole portions are set to a constant value (8.75 °). 4B, 4C, and 4D show torque ripple contents of the permanent magnet built-in type synchronous motor of FIGS. From this figure, it can be seen that the torque ripple can be greatly reduced according to the embodiment of the present invention.
[0033]
FIG. 5 is a diagram showing a configuration of a rotor according to a fourth embodiment of a synchronous motor with a built-in permanent magnet of the present invention. The configuration on the stator core side is the same as that of the embodiment of FIG. 4, the same reference numerals as those in FIG. 1 are attached to the same parts as those in the embodiment shown in FIG. In this embodiment, eight (2p) permanent magnet magnetic pole portions 12a..., 12b..., And four (p) permanent magnets in the first group are arranged at equal intervals every other circumferential direction. .. And a second group of four (p) permanent magnet magnetic pole portions 12b... Which are located at equal intervals in the circumferential direction. Also, the eight (2p) magnetic salient poles 9 ... and 10 ... are also four (p) magnetic salient poles of the first group located at equal intervals in the circumferential direction. .. And a second group of four (p pieces) magnetic salient pole portions 10... Located at equal intervals in the circumferential direction. The opening angle α1 of the four magnetic salient pole portions 9 of the first group is made smaller than the opening angle α2 of the four magnetic salient pole portions 10 of the second group. Also in this embodiment, the opening angle α1 and the opening angle α2 satisfy the above equation (1).
[0034]
Specifically, since the slot pitch of the stator core is 7.5 ° and the slot opening is 2.1 °, the opening angle α2 is preferably 12.9 ° ≦ α2 ≦ 17.1 °, The opening angle α1 is preferably a value of 5.4 ° ≦ α1 ≦ 9.6 °. In this example, α2 is 16 ° and α1 is 6.5 °.
[0035]
In this example, the outer peripheral surface of the rotor core 7 formed by the magnetic salient pole portions 9 or 10 located between the two adjacent permanent magnet magnetic pole portions 12a and 12b and the two adjacent permanent magnet magnetic pole portions 12a and 12b. The partial shape is centered on salient pole virtual center lines CL1 and CL2 passing through the center of the magnetic salient pole part 9 or 10 located between the two permanent magnet magnetic pole parts 12a and 12b adjacent from the center of the shaft 6. So that the outer peripheral surface shape of the rotor core 7 becomes a four-equal shape (p uniform shape) in which the outer peripheral surface partial shapes in the angular range of 90 ° (360 ° / p) are all equal in the circumferential direction. Further, the shapes of the eight permanent magnet magnetic pole portions 12a ... and 12b ... and the eight magnetic salient pole portions 9 ... and 10 ... are defined. In this way, even when the opening angles α1 and α2 of the magnetic salient poles 9... 10 are different, the circumferential magnetic balance is balanced, and thus the voltage imbalance of each phase. And rotor eccentric force does not occur.
[0036]
In this example, the dimension δd of the gap formed between the magnetic pole surfaces of the permanent magnet magnetic pole portions 12a... And 12b... And the magnetic pole surfaces of the plurality of magnetic pole portions of the stator core satisfies the following equation (2). It is determined to be a cosec gap.
[0037]
δd = δd0 / cos [p (θm−θdm)] (2)
Here, δd0 is the minimum value of the gap dimension, and θm is two salient pole virtual centers passing through the center of the magnetic salient pole located between the two permanent magnet magnetic poles adjacent from the center of the shaft. Is an angle from the virtual center line CL3 passing through the center of the line (CL1, CL2) to the magnetic salient pole portion side having the opening angle α1, and θdm is the virtual center line from the virtual line PL3 where the gap dimension is the minimum value The angle is up to CL3.
[0038]
Here, θdm for minimizing the cogging torque is determined by the equation θdm≈ (ψ2-ψ1) / 2 when angles ψ1 and ψ2 described later are used. However, when the magnetic flux density distribution from the permanent magnets in the gap is greatly broken from the sine wave, the cogging torque is in the range of (1/6) × x × τs ≦ θdm ≦ (1/2) × xx × τs. There is a value that minimizes. Here, x is a natural number that makes θdm closest to the value of (ψ2−ψ1) / 2 when approximated as θdm≈ (ψ2−ψ1) / 2≈ (1/4) × x × τs.
[0039]
The shapes of the magnetic pole surfaces of the permanent magnet magnetic pole portions 12a and 12b are determined by arcs or elliptical arcs so as to be close to values determined by the above formula.
[0040]
Further, in this example, the radius of curvature R1 of the magnetic salient pole portion 9 with the open angle α1 is made smaller than the radius of curvature R2 of the magnetic salient pole portion with the open angle α2. If the radius of curvature R1 of the magnetic pole faces of the p magnetic salient pole portions of the first group is smaller than the radius of curvature R2 of the magnetic pole faces of the p magnetic salient pole portions of the second group, the curvature Compared to the case where the radii R1 and R2 are the same, the torque ripple can be reduced. In order to increase the torque, it is desirable that the curvature radii R1 and R2 are larger than the curvature radii of the end portions of the magnetic pole surfaces of the adjacent permanent magnet magnetic pole portions and that R1 <R2. FIG. 6 shows the result of measuring the torque ripple content by making Model 1 to Model 3 under the conditions shown in order to confirm the effect when the radius of curvature is changed. As can be seen from the measurement results, R1 <R2.
It can be seen that the torque ripple content is the smallest in the case of Model 3.
[0041]
In the above formula, the gap when θdm = 0 ° forms a so-called general cosec gap. If such a gap configuration is adopted, the permanent magnet in the gap is used regardless of the rotation direction of the motor. Can be made close to a sine wave, and cogging torque can be suppressed. Further, when θdm is set to a value in the range of 1/6 slot pitch to 1/2 slot pitch, the cogging torque is dramatically increased while maintaining the sinusoidal magnetic flux distribution from the permanent magnet in the gap in a sine wave shape. Can be suppressed. Incidentally, in the embodiment of FIG. 5, θm is set to 2 °.
[0042]
In this embodiment, the magnetic field having the open angle α2 of the two virtual lines PL1 and PL2 passing from the center of the virtual center line CL3 and the shaft 6 to both ends of the magnetic pole surface of the permanent magnet magnetic pole portion 12a or 12b in the circumferential direction. The angle ψ1 between the imaginary line PL1 located on the side of the salient pole 10 and the two passing through both ends in the circumferential direction of the magnetic pole surface of the permanent magnet magnetic pole part 12a or 12b from the center of the virtual center line CL3 and the shaft 6 The angle ψ2 between the virtual lines PL1 and PL2 and the virtual line PL2 located on the magnetic salient pole portion 9 side having the opening angle α1 satisfies the following conditional expressions (3) to (6). It has become.
[0043]
ψ2> ψ1 (3)
ψ2−ψ1≈0.5 (2m−1) τs− (180 ° / p) (4)
ψ2 + ψ1 ≒ u · τs (5)
α1 + α2 ≦ (360 ° / p) −2 (ψ2 + ψ1) (6)
Here, p is the number of pole pairs, and m and u are arbitrary natural numbers. If this condition is satisfied, the cogging torque can be brought close to the minimum value.
[0044]
Specifically, in this example, the angle ψ1 is preferably a value in the range of 11.0525 ° ≦ ψ1 ≦ 15.225 °, and the angle ψ2 is a value in the range of 14.775 ° ≦ ψ2 ≦ 18.975 °. Moreover, it is preferable that the angle ψ1 and the angle ψ2 satisfy the relationship of 1.65 ° ≦ ψ2-ψ1 ≦ 5.85 ° and 27.9 ° ≦ ψ2 + ψ1 ≦ 32.1 °.
[0045]
In this example, the angle ψ1 is 13.125 °, and the angle ψ2 is 16.875 °. Assuming that this angle is τs = 7.5 °, p = 4, m = 7, u = 4, and substituting these values into the above equations (4) and (5),
ψ2−ψ1≈0.5 (2m−1) τs− (180 ° / p) (4)
ψ2 + ψ1 ≒ u · τs (5)
φ2−φ1 = 0.5 (2m−1) τs− (180 ° / p) = 0.5 × (2 × 7-1) × 7.5− (180/4) = 3.75 °
ψ2 + ψ1 = u · τs = 4 × 7.5 = 30 °
From these two equations, ψ1 = 13.125 ° and ψ2 = 16.875 ° are obtained.
[0046]
Further, when the optimum range of θdm and θdm for minimizing the cogging torque is obtained based on the values of the angles ψ1 and ψ2, θdm = (ψ2-ψ1) / 2 = (16.875-13.125) /2=1.875°. Therefore, the cogging torque can be minimized at θdm = 1.875 °. Here, when x satisfying the formula θdm≈ (ψ2−ψ1) / 2≈ (1/4) × x × τs is obtained, x satisfying (1/4) × x × τs = 1.875 is 1. It becomes.
[0047]
Therefore, if x = 1 and τs = 7.5 ° are added to the above-described equation (1/6) × x × τs ≦ θdm ≦ (1/2) × xxτs for obtaining the range of θdm, 25 ° ≦ θdm ≦ 3.75 ° is determined as the optimum value range of θdm.
[0048]
As shown in FIG. 7, the circumferential widths (openings) of the grooves 11a and 11b are set to 2.25 ° and 1.5 °. Moreover, in this example, as shown in FIG. 7, the shape of the 1st and 2nd nonmagnetic parts 13a and 13b with respect to one permanent magnet formed in the rotor core 7 is varied.
[0049]
In this embodiment, when α1 and α2 and ψ2 and ψ1 satisfy the following equations (7) and (8), the torque ripple can be brought close to the minimum value.
[0050]
(180 ° / 2p) + (α1 / 2) -ψ2 = (¼) (2v1-1) τs (8)
(180 ° / 2p) + (α2 / 2) −ψ1 = (1/4) (2v2-1) τs (9)
Here, v1 and v2 are arbitrary natural numbers.
[0051]
In this example, the angle of each part is set so as to satisfy the conditions (8) and (9).
[0052]
The condition of the angle of each part that minimizes the torque ripple can be obtained by solving the simultaneous equations of the above expressions (3), (4), (5), and (6). FIG. 8 is a diagram showing the relationship between ψ2, ψ1, and m that minimizes the cogging torque in an 8-pole 48-slot distributed winding synchronous motor. The vertical axis is ψ2, and the horizontal axis is ψ1. In FIG. 8, the circled points are the condition points at which the torque ripple determined by the selected values of m and u is minimized.
[0053]
FIG. 9 shows the relationship between α1, α2 and n obtained from the above equations (1), (8) and (9). When practicing the present invention, the torque ripple can be minimized if the relationship between α1 and α2 is determined so as to satisfy this relationship.
[0054]
【The invention's effect】
According to the present invention, there is an advantage that cogging torque can be suppressed and torque pulsation can be suppressed.
[Brief description of the drawings]
FIG. 1 is a diagram conceptually showing the structure of a first embodiment of a synchronous motor with a built-in permanent magnet of the present invention.
FIG. 2 is a diagram showing a configuration of a rotor used in a permanent magnet built-in type synchronous motor according to a second embodiment of the permanent magnet built-in type synchronous motor of the present invention.
FIG. 3 is a view showing a configuration of a rotor used in a permanent magnet built-in type synchronous motor according to a third embodiment of the permanent magnet built-in type synchronous motor of the present invention;
4 is data obtained by measuring a torque ripple content rate in the embodiment of FIGS. 1 to 3. FIG.
FIG. 5 is a diagram conceptually showing the structure of a fourth embodiment of a synchronous motor with a built-in permanent magnet of the present invention.
FIG. 6 is a diagram illustrating a torque ripple reduction effect when the curvature radii R1 and R2 are changed.
7 is a partially enlarged view of the embodiment of FIG.
FIG. 8 is a diagram showing the relationship between ψ2, ψ1, and χ that minimizes the cogging torque in an 8-pole 48-slot distributed winding synchronous motor.
FIG. 9 shows the relationship between α1 and α2 that minimizes torque ripple obtained from equations (1), (8), and (9).
[Explanation of symbols]
1 Stator
2 York
3 Teeth (magnetic pole)
4 slots
5 Rotor
6 Shaft
7 Rotor core
8 Permanent magnet
9, 10 Magnetic salient pole

Claims (11)

A stator formed by winding one or more phases on a plurality of magnetic pole portions of the stator core;
The number of pole pairs is p (where p is a positive integer equal to or greater than 1), and 2p permanent magnets are built in the rotor core fixed to the shaft at intervals in the circumferential direction. Synchronous type with built-in permanent magnet comprising a rotor having 2p permanent magnet magnetic pole portions formed on the outer periphery of the rotor core and 2p magnetic salient pole portions formed so as to sandwich the permanent magnet magnetic pole portions therebetween A motor,
The 2p magnetic salient poles are equally spaced apart from the first group of p magnetic salient poles located at equal intervals in the circumferential direction. A second group of p magnetic salient poles located at
An opening angle α1 of the p magnetic salient pole portions of the first group is smaller than an opening angle α2 of the p magnetic salient pole portions of the second group,
The opening angle α1 and the opening angle α2 are determined so as to satisfy the following formula:
α2−α1≈2β− (2n−1) τs
Here, n is a natural number, β is an angle between two salient pole virtual center lines (CL1, CL2) passing through the centers of the two magnetic salient poles adjacent from the center of the shaft, τs is a slot pitch of the stator core, and is a permanent magnet built-in type synchronous motor. The curvature radius R1 of the magnetic pole faces of the p magnetic salient pole portions of the first group is smaller than the curvature radius R2 of the magnetic pole faces of the p magnetic salient pole portions of the second group. The synchronous motor with a built-in permanent magnet according to claim 1. The shapes of the 2p permanent magnet magnetic pole portions and the 2p magnetic salient pole portions are:
An outer peripheral surface portion shape of the rotor core formed by two adjacent permanent magnet magnetic pole portions and the magnetic salient pole portion positioned between the two adjacent permanent magnet magnetic pole portions is formed adjacent to the shaft from the center. Are symmetrical with respect to the salient pole virtual center line (CL1, CL2) passing through the center of the magnetic salient pole located between the two permanent magnet magnetic poles.
3. The built-in permanent magnet according to claim 1, wherein the outer peripheral surface shape of the rotor core is determined to be a p-equal shape in which the outer peripheral surface partial shapes in the angular range of 360 ° / p are all equal in the circumferential direction. Type synchronous motor. The magnetic pole surface of the permanent magnet magnetic pole portion is formed by an arc surface or an elliptical arc surface,
A dimension δd of a gap formed between the magnetic pole surface of the permanent magnet magnetic pole portion and the magnetic pole surfaces of the plurality of magnetic pole portions of the stator core is determined so as to satisfy or substantially satisfy the following expression: ,
δd = δd0 / cos [p (θm−θdm)]
Here, δd0 is the minimum value of the gap dimension, and θm is two values passing through the center of the magnetic salient pole portion located between the two adjacent permanent magnet magnetic pole portions from the center of the shaft. The angle from the virtual center line (CL3) passing through the center of the salient pole portion virtual center line (CL1, CL2) to the magnetic salient pole portion side having the opening angle α1, and θdm is the dimension of the gap The synchronous motor with a built-in permanent magnet according to claim 2, wherein the angle is an angle from an imaginary line (PL3) at which the minimum value is reached to the imaginary center line (CL3). Of the two virtual lines (PL1, PL2) passing through the virtual center line (CL3) and both ends of the magnetic pole surface of the permanent magnet magnetic pole part from the center of the shaft in the circumferential direction, the magnetic angle having the opening angle α2 The angle ψ1 between the imaginary line (PL1) located on the salient pole part side and the two passing through both ends in the circumferential direction of the magnetic pole face of the permanent magnet magnetic pole part from the virtual center line (CL3) and the center of the shaft The angle ψ2 between the virtual line (PL1, PL2) and the virtual line (PL2) located on the magnetic salient pole side having the opening angle α1 satisfies the following conditional expression:
ψ2> ψ1
ψ2-ψ1 ≒ 0.5 (2m-1) τs- (180 ° / p)
ψ2 + ψ1 ≒ u ・ τs
α1 + α2 ≦ (360 ° / p) −2 (ψ2 + ψ1)
5. The permanent magnet built-in type synchronous motor according to claim 2, 3 or 4, wherein m and u are arbitrary natural numbers. The α1 and α2 and the ψ2 and ψ1 further satisfy the following equation:
(180 ° / 2p) + (α1 / 2) −ψ2≈ (1/4) (2v1-1) τs
(180 ° / 2p) + (α2 / 2) −ψ1≈ (1/4) (2v2-1) τs
6. The permanent magnet built-in type synchronous motor according to claim 5, wherein v1 and v2 are arbitrary natural numbers. The rotor core has first and second nonmagnetic portions formed by air gaps on both sides in the circumferential direction of the permanent magnet,
The first non-magnetic portion is located on the side of the magnetic salient pole with the opening angle α1, and the second non-magnetic portion is located on the side of the magnetic salient pole with the opening angle α2. And
The shapes of the first and second nonmagnetic portions are different so that the cross-sectional area is the same or the cross-sectional shape of the second nonmagnetic portion is larger than the cross-sectional shape of the first nonmagnetic portion. The synchronous motor with a built-in permanent magnet according to claim 1, 2, 3, 4, 5 or 6. A stator formed by three-phase windings on a plurality of magnetic pole portions of the stator core;
The number of pole pairs is four, and eight permanent magnets are built in the rotor core fixed to the shaft at intervals in the circumferential direction. The eight permanent magnets provide eight permanent magnet magnetic pole portions on the outer periphery of the rotor core. And a permanent motor with a built-in permanent magnet comprising a rotor having eight magnetic salient pole portions formed so as to sandwich the permanent magnet magnetic pole portion therebetween,
The eight permanent magnet magnetic pole portions are arranged at equal intervals in every other circumferential direction and every other permanent magnet magnetic pole portion of the first group located at equal intervals in the circumferential direction. It consists of four permanent magnet magnetic pole parts of two groups,
The eight magnetic salient poles are equally spaced apart from each other in the circumferential direction with the four magnetic salient poles of the first group located at equal intervals in the circumferential direction. A second group of four magnetic salient poles located at
The opening angle α1 of the four magnetic salient pole portions of the first group is smaller than the opening angle α2 of the four magnetic salient pole portions of the second group,
When the slot pitch of the stator core is 7.5 ° and the slot opening is 2.1 °, the opening angle α2 is a value of 12.9 ° ≦ α2 ≦ 17.1 °, and the opening angle α1 is 5 A synchronous motor with a built-in permanent magnet, which has a value of .4 ° ≦ α1 ≦ 9.6 °. The shapes of the eight permanent magnet magnetic pole portions and the eight magnetic salient pole portions are as follows:
The shape of the outer peripheral surface portion of the rotor core formed by the two adjacent permanent magnet magnetic pole portions and the magnetic salient pole portion positioned between the two adjacent permanent magnet magnetic pole portions is adjacent to the center of the shaft. Axisymmetrical center line (CL1, CL2) passing through the center of the magnetic salient pole part located between the two permanent magnet magnetic pole parts is symmetric with respect to the center.
9. The permanent magnet built-in type synchronous motor according to claim 8, wherein the outer peripheral surface shape of the rotor core is determined to be a four-equal shape in which the outer peripheral surface partial shapes in an angular range of 90 ° in the circumferential direction are all equal. A virtual center line (CL3) passing through the centers of the two salient pole virtual center lines adjacent from the center of the shaft, and the two passing through both ends in the circumferential direction of the magnetic pole surface of the permanent magnet magnetic pole part from the center of the shaft. The angle ψ1 between the imaginary line (PL1, PL2) and the imaginary line (PL1) located on the side of the magnetic salient pole having the opening angle α2 is 11.025 ° ≦ ψ1 ≦ 15.225 °. Value in the range of
Of the two virtual lines (PL1, PL2) passing through the virtual center line (CL3) and both ends of the magnetic pole surface of the permanent magnet magnetic pole portion from the center of the shaft in the circumferential direction, the magnetic angle having the opening angle α1. The angle ψ2 between the imaginary line (PL2) located on the side of the salient pole is a value in the range of 14.775 ° ≦ ψ2 ≦ 18.975,
10. The permanent magnet according to claim 9, wherein the angle ψ1 and the angle ψ2 satisfy a relationship of 1.65 ° ≦ ψ2-ψ1 ≦ 5.85 ° and 27.9 ° ≦ ψ2 + ψ1 ≦ 32.1 °. Built-in synchronous motor. The magnetic pole surface of the permanent magnet magnetic pole portion is formed by an arc surface or an elliptical arc surface,
A dimension δd of a gap formed between the magnetic pole surface of the permanent magnet magnetic pole portion and the magnetic pole surfaces of the plurality of magnetic pole portions of the stator core is determined so as to satisfy or substantially satisfy the following expression: ,
δd = δd0 / cos [p (θm−θdm)]
Here, δd0 is the minimum value of the gap dimension, and θm is two values passing through the center of the magnetic salient pole portion located between the two adjacent permanent magnet magnetic pole portions from the center of the shaft. The angle from the virtual center line (CL3) passing through the center of the salient pole virtual center line (CL1, CL2) to the magnetic salient pole side having the opening angle α1, and the θdm is 1.25 ° The synchronous motor with a built-in permanent magnet according to claim 10, wherein the value is in a range of ≦ θdm ≦ 3.75 °.

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