JP2009118739A - Manufacturing method of permanent magnet type rotating electric machine, and the permanent magnet type rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a permanent-magnet type rotating electric machine, whereby not only the fundamental components of its cogging torque is reduced, but also the higher harmonic components of its cogging torque are reduced. <P>SOLUTION: With respect to the manufacturing method of the permanent-magnet type rotating electrical machine having a rotor and a stator, in the rotor, two-stage permanent magnets provided in its axial direction are so disposed on the outer peripheral surface of its core that the permanent magnets are made skew, in its core periphery direction by a stage-skewing angle of θe (electrical angle) and is interposed between the two stages. Furthermore, in the stator, the rotor is disposed in its inside, and its cylindrical core has a stator winding for so generating a rotating magnetic field as to rotate the rotor. Moreover, the relation existing between the stage-skewing angle and the fundamental component of a cogging torque of the rotating electrical machine is searched from the magnetic characteristics of the rotor core. Furthermore, a stage-skewing angle such that the cogging torque becomes smaller than the one obtained when the stage-skewing angle is equal to a theoretical angle of θs (electric angle), is set as the stage-skewing angle of θe. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a permanent magnet type rotating electrical machine such as an electric motor, and more particularly to a permanent magnet type rotating electrical machine designed to reduce cogging torque.

  In a general configuration of a permanent magnet type rotating electric machine, a rotor is disposed in a stator. The stator is provided with a plurality of stator windings on the inner periphery of a cylindrical stator core to form a plurality of magnetic poles. The rotor is provided with a rotor core so that the rotor can be rotated about the center of the stator, and a permanent magnet is provided on or inside the rotor core. The permanent magnet has alternating N and S poles. It is arranged to line up. In this rotating electrical machine, the rotor is rotated around the rotation axis by appropriately energizing the stator windings to form a rotating magnetic field.

  In the permanent magnet type rotating electrical machine as described above, a fluctuation in rotational torque called cogging torque occurs. The cogging torque not only generates vibration and noise, but also causes a decrease in the control performance of the rotating electrical machine.

  Conventionally, in order to reduce the cogging torque, a plurality of permanent magnets are arranged in the axial direction of the rotor core and shifted in the circumferential direction of the rotor core. The permanent magnets are aligned with the stator core surface at an angle of skew angle θm (hereinafter referred to as a step skew angle), for example, so that the position in the circumferential direction is shifted depending on the axial position of the rotor core (for example, step skew angle). Patent Document 1).

  The step skew angle θm (mechanical angle) uses a theoretically obtained angle (hereinafter referred to as a theoretical angle). The theoretical angle (mechanical angle) at which the cogging torque is minimized is determined by (360 / the least common multiple of the number of stator magnetic poles and the number of rotor magnetic poles) / the number of stages of the axial permanent magnet. When the number of stator magnetic poles of the rotating electrical machine is 12, the number of rotor magnetic poles is 8, and the number of permanent magnets is 2, the step skew angle θm is 7.5 ° (the electrical angle θe is 30 °. = Calculated from the relational expression of mechanical angle × number of poles / 2) (for example, Patent Document 2).

  However, when the step skew angle θm is theoretically determined as described above and applied to an actual rotating electrical machine, it is considered that the reduction of the cogging torque is still insufficient. The reason is that the axial leakage magnetic flux is generated by adopting the step skew, but the influence of magnetic saturation due to this leakage magnetic flux is not taken into consideration. The leakage magnetic flux that causes the cogging torque includes the stepped portion of the permanent magnet and the leakage magnetic flux inside the rotor core, but the leakage magnetic flux inside the stator core is the main cause of the cogging torque.

Japanese Utility Model Laid-Open Publication No. 61-17876 (page 4-6, FIG. 1-6) Japanese Unexamined Patent Publication No. 2000-308286 (page 3-4, FIG. 2, FIG. 3)

  As described above, the conventional rotating electric machine employing the step skew has a problem that the cogging torque cannot be sufficiently reduced because the theoretical angle is adopted as the step skew angle.

  The present invention solves the above-mentioned problems, and can reduce the cogging torque more efficiently than the case where the theoretical angle is adopted as the step skew angle, and can also reduce the torque ripple. A rotating electrical machine is provided.

In the method for manufacturing a permanent magnet type rotating electrical machine according to the present invention, two stages of permanent magnets are provided in the axial direction on the outer peripheral surface of the rotor core, and the permanent magnet is stepped in the circumferential direction of the rotor core between two stages. A rotor having a skew angle θe (electrical angle) and a cylindrical stator core provided with a stator winding in which the rotor is disposed inside and a rotating magnetic field for rotating the rotor is provided. In a method of manufacturing a permanent magnet type rotating electrical machine having a stator,
The lower limit of the step skew angle θe is the theoretical angle θs (electrical angle),
The upper limit value of the step skew angle θe is approximately 3/2 times the value of the theoretical angle θs,
The step skew angle θe is set to be larger than the lower limit value and equal to or smaller than the upper limit value.
However,
θs = (180 × rotor magnetic pole number / stator magnetic pole number and least common multiple of rotor magnetic pole number) / 2 (electrical angle)

  In addition, another method of manufacturing a permanent magnet type rotating electrical machine according to the present invention obtains the relationship between the step skew angle and the cogging torque of the fundamental wave component of the cogging torque from the magnetic characteristics of the rotor core, and the step skew angle is theoretically The step skew angle is smaller than the cogging torque at the angle θs (electrical angle), and the step skew angle θe is set as the step skew angle θe.

  In the permanent magnet type rotating electrical machine according to the present invention, the lower limit value of the step skew angle θe is a theoretical angle θs (electrical angle), and the upper limit value of the step skew angle θe is approximately 3 / of the value of the theoretical angle θs. The step skew angle θe is set to be larger than the lower limit value and equal to or smaller than the upper limit value, and the number of permanent magnets per step provided on the outer peripheral surface of the rotor core is 4 ×. N (N is a natural number), and two permanent magnets adjacent in the circumferential direction are a pair of permanent magnets, and 4 × N permanent magnets are evenly arranged on the entire circumference of the outer peripheral surface Thus, every other pair of permanent magnet pairs is arranged in a state shifted by ½ of the theoretical angle θs to one of the circumferential directions of the outer peripheral surface.

  Another permanent magnet type rotating electrical machine according to the present invention obtains the relationship between the step skew angle and the cogging torque of the fundamental component of the cogging torque from the magnetic characteristics of the rotor core, and the step skew angle is the theoretical angle θs ( The step skew angle at which the cogging torque is smaller than the cogging torque at the time of electrical angle) is set as the step skew angle θe, and the number of permanent magnets per step provided on the outer peripheral surface of the rotor core is 4 × N (N is a natural number), and two permanent magnets adjacent in the circumferential direction are a pair of permanent magnets, and 4 × N permanent magnets are evenly arranged on the entire circumference of the outer peripheral surface Thus, every other pair of permanent magnet pairs is arranged in a state shifted by ½ of the theoretical angle θs to one of the circumferential directions of the outer peripheral surface.

  According to the method for manufacturing a permanent magnet type rotating electrical machine and the permanent magnet type rotating electrical machine according to the above invention, the cogging torque fundamental wave component can be reduced and the cogging torque harmonic component can be reduced as compared with the case where the step skew angle θe is the theoretical angle θs. And torque ripple can be reduced.

1 is a perspective view showing a first embodiment of a permanent magnet type rotating electric machine according to the present invention. It is sectional drawing which shows Embodiment 1 of the permanent-magnet-type rotary electric machine which concerns on this invention. It is a side view which shows Embodiment 1 of the permanent magnet type rotary electric machine which concerns on this invention. It is a top view which shows Embodiment 1 of the permanent magnet type rotary electric machine which concerns on this invention. It is a figure which shows the result of the cogging torque fundamental wave component obtained by implementing a three-dimensional magnetic field analysis about the rotor and rotary electric machine shown in FIGS. It is a figure which shows the result of the cogging torque 2nd harmonic component obtained by implementing a three-dimensional magnetic field analysis about the rotor and rotary electric machine shown in FIGS. It is a figure which shows the magnetic characteristic of the rotor core used for the three-dimensional analysis. It is a figure which shows the 5th-order and 7th-order skew coefficient with respect to a stage skew angle. It is a figure which shows the torque ripple 6f component coefficient with respect to a step skew angle. It is a perspective view which shows Embodiment 2 of the permanent magnet type rotary electric machine which concerns on this invention. It is sectional drawing which shows Embodiment 2 of the permanent-magnet-type rotary electric machine which concerns on this invention. It is a perspective view which shows Embodiment 3 of the permanent magnet type rotary electric machine which concerns on this invention. FIG. 10 is a perspective view showing a configuration of a stator block in a third embodiment. FIG. 6 is a cross-sectional view of a stator block in a third embodiment.

  Hereinafter, a preferred embodiment of a permanent magnet type rotating electrical machine according to the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG.
1, 2, 3 and 4 are a perspective view, a cross-sectional view, a side view and a plan view showing Embodiment 1 of the present invention, and FIGS. 1 to 3 show the arrangement of permanent magnets in the rotor. Is described.

  As shown in FIG. 1 to FIG. 3, the rotor 30 has an upper permanent magnet 32 a and a lower permanent magnet 32 b attached to the outer peripheral surface of the rotor core 31, so that the rotor 30 has a circumference of a step skew angle θe (electrical angle). The N poles and the S poles are alternately arranged so as to be displaced in the direction. The number of magnetic poles of the rotor 30 is 8, and the number of stages of permanent magnets is 2.

  As shown in FIG. 4, the stator 20 has a plurality of stator windings 22 provided on the inner periphery of a cylindrical stator core 21 to form a plurality of magnetic poles. The rotor 30 is provided with a rotor core 31 so as to be able to rotate with the center of the stator 20 as a rotation axis. By appropriately energizing the stator winding 22 and forming a rotating magnetic field, the rotor 30 is It rotates around the axis of rotation.

  As shown in FIGS. 2, 3 and 4, the lower permanent magnet 32b is shifted in the circumferential direction by 36 ° in electrical angle (8 ° in mechanical angle) with respect to the reference line A of the upper permanent magnet 32a. Yes. That is, the step skew angle θe is calculated by the following formula: (180 × number of rotor magnetic poles / number of stator magnetic poles and least common multiple of the number of rotor magnetic poles) / 2 (the number of stages of axial permanent magnets). ) Is a larger value. As described above, the equation representing the step skew angle in terms of the mechanical angle is (360 / the least common multiple of the number of stator magnetic poles and the number of rotor magnetic poles) / 2 (the number of steps of the axial permanent magnet). The required theoretical angle (mechanical angle) is larger than 7.5 °.

  The step skew angle θe is larger than the theoretical angle θs, and is set to be equal to or less than the maximum value of the step skew angle θe obtained according to the magnetic characteristics of the stator core 21 and the rotor core 31 as described later. Cogging torque can be reduced more efficiently than when θe is the theoretical angle θs, and torque ripple can also be reduced. Hereinafter, the relationship between the cogging torque and torque ripple and the step skew angle θe will be described, and in this embodiment, the cogging torque and torque ripple can be reduced.

  FIGS. 5 and 6 performed a three-dimensional magnetic field analysis on the rotor and the rotating electrical machine (the number of rotor magnetic poles is 8, the number of stator magnetic poles is 12, and the number of permanent magnet stages is 2) shown in FIGS. The result is shown.

  FIG. 5 shows the result regarding the cogging torque fundamental wave component, and FIG. 6 shows the result regarding the second harmonic of the cogging torque. The ratio of the cogging torque when the step skew is applied to the cogging torque when there is no step skew, respectively. The relationship between the cogging torque ratio and the step skew angle (electrical angle) θe, when the magnetic characteristics of the stator core 20 are ideal (magnetic characteristics A), and when the magnetic characteristics are deteriorated during the machining process (Magnetic characteristic B), a case where the magnetic characteristic is further deteriorated by machining (magnetic characteristic C).

  FIG. 7 shows magnetic characteristics A, B, and C (relationship of BH characteristics) of the stator core 20 used for the analysis. The magnetic flux density ratio in the figure represents the ratio to the reference value with the saturation magnetic flux density of the material having the magnetic property A as the reference value. The magnetic characteristic A is a magnetic characteristic corresponding to the catalog value, and shows a case where there is no influence of processing, the magnetic characteristic B corresponds to the actual machine state, and the magnetic flux density ratio in the vicinity of the magnetizing force H = 1000 A / m is the magnetic characteristic A. The magnetic characteristic C has a characteristic in which the magnetic flux density ratio in the vicinity of the magnetizing force H = 1000 A / m is reduced by about 40% compared to the magnetic characteristic A. is there.

  As shown in FIG. 5, with respect to the cogging torque fundamental wave component, the step skew angle θe at which the cogging torque ratio becomes the minimum as the magnetic characteristics of the stator core deteriorate from the magnetic characteristics A to the magnetic characteristics B and C in sequence. It can be seen that this is large (this is because, as described above, when step skew is employed, axial leakage magnetic flux is generated inside the stator core). That is, as the magnetic characteristics of the stator core deteriorate, the step skew angle θe at which the cogging torque is minimized is larger than the theoretical angle 30 °. Accordingly, in the magnetic characteristic B, when the step skew angle θe is set to a theoretical angle of 30 °, the cogging torque ratio at the point (1) (about 0.18) is obtained, whereas the theoretical angle exceeds 30 °. By setting the cogging torque ratio (0.18) or less at the point (1) below the maximum value of the step skew angle θe (the step skew angle θe (about 37 °) at the point (2)), the cogging torque is reduced. The fundamental wave component can be reduced to a value lower than or lower than the theoretical angle of 30 °. Similarly, in the magnetic characteristic C, the step skew angle θe at the point (3) is equal to or less than the cogging torque ratio (about 0.23) (step skew angle θe at the point (4) = about 43 °. ) By making the following, the fundamental wave component of the cogging torque can be reduced to be lower or lower than that when the theoretical angle is 30 °.

  In the above, the case where the ratio between the number of rotor magnetic poles and the number of stator magnetic poles is 2: 3 has been described. As is apparent from the above description of FIG. 5, the ratio between the number of rotor magnetic poles and the number of stator magnetic poles. When the ratio is a predetermined value, the lower limit value of the step skew angle θe set in the actual machine is set to a value larger than the theoretical angle θs, and the upper limit value of the step skew angle θe is the relationship between the cogging torque ratio and the step skew angle θe. Thus, depending on the magnetic characteristics (BH characteristics) of the stator core, by making it not more than the maximum value of the stage skew angle θe that is not more than the cogging torque ratio at the theoretical angle θs, it is lower than the theoretical angle θs, or Below that, the fundamental wave component of the cogging torque can be reduced.

  Next, as shown in FIG. 6, with respect to the second harmonic component of the cogging torque, the cogging torque ratio is minimized at 1/2 or 3/2 of the theoretical angle θs (electrical angle 15 °, electrical angle 45 °). I understand. This is because the cogging torque harmonic component is less susceptible to the influence of magnetic flux leakage in the axial direction (the effect of magnetic saturation), and the step skew angle θe is the theoretical angle to reduce the second harmonic component of the cogging torque. It is considered that 1/2 of θs or 3/2 is good.

  On the other hand, the relationship between the torque ripple during energization and the stage skew angle is generally examined using a winding coefficient called a skew coefficient. The skew coefficient κsv for the ν th harmonic component in the rotating electrical machine is given by the following equation (2). Where γ is a skew angle.

  κsv = sin (νγ / 2) / (νγ / 2) (2)

  Here, assuming that the step skew angle is γd, γd = γ / 2. Therefore, the skew coefficient κdsv when the step skew is employed is given by the following equation (3).

  κdsv = sin (νγd) / (νγd) (3)

  In addition, the torque ripple of the permanent magnet type rotating electrical machine is dominated by a component 6 times the power frequency (hereinafter referred to as 6f component). Generally, the torque ripple 6f component is generated due to the fifth and seventh harmonic components.

  FIG. 8 is a diagram showing fifth-order and seventh-order skew coefficients with respect to the step skew angle γd calculated from the above equation (2). The influence degree of the fifth and seventh harmonic components on the torque ripple 6f component is considered to be approximately related to the inverse of the square of the order, and the influence degree of the fifth component is 1/52 = 0.04, the seventh order. The influence degree of the component is considered to be 1/72 = 0.02.

  FIG. 9 is a diagram showing the torque ripple 6f component coefficient with respect to the step skew angle in consideration of the skew coefficient of FIG. 8 and the degree of influence regarding the fifth and seventh order torque ripple 6f components. From the figure, the torque ripple 6f component coefficient is smaller than the torque ripple 6f component coefficient at 30 ° when the step skew angle γd exceeds 30 °. Therefore, it is considered that the torque ripple 6f component can be reduced by setting the step skew angle γd to 30 ° or more, which is the theoretical angle θs with respect to the cogging torque fundamental wave component.

Embodiment 2. FIG.
10 is a perspective view showing a second embodiment of the present invention, and FIG. 11 is a cross-sectional view in a direction perpendicular to the axial direction of the rotor core 31 of FIG.

  As shown in FIG. 10, the step skew angle θe of the upper permanent magnet 32a and the lower permanent magnet 32b is the same as in the first embodiment.

  Moreover, as shown in FIG. 11, the adhering position with respect to the rotor core 31 for each of the two poles (N-S) of the permanent magnets 32a and 32b in each stage is shifted, and the adjacent electrical angle for each two poles is One is close to 15 ° (mechanical angle 3.75 °) from the same angle, and the other is 15 ° (mechanical angle 3.75 °) away from the same angle.

  According to this embodiment, the cogging torque fundamental wave component can be reduced by the step skew angle θe of the upper permanent magnet 32a and the lower permanent magnet 32b, and the two poles of the permanent magnets 32a and 32b ( NS) The cogging torque is shifted by shifting the position of the attachment to the rotor core 31 by moving the adjacent electrical angles of every two poles closer to 15 ° from the same angle, and 15 ° away from the other. Harmonic components can be reduced.

  From the above, it is clear that the electrical angle shifted from the equal angle may be ½ of the theoretical angle θs.

Embodiment 3 FIG.
12 is a perspective view showing a third embodiment of the present invention, FIG. 13 is a perspective view showing a configuration of the stator block in the third embodiment, and FIG. 14 is a block diagram of the stator in the third embodiment. It is sectional drawing.

  In this embodiment, when the ratio between the number of rotor magnetic poles and the number of stator magnetic poles is a predetermined value, the lower limit value of the step skew angle θe set in the actual machine is set to a value larger than the theoretical angle θs, and the step skew is set. The upper limit of the angle θe is determined based on the relationship between the cogging torque ratio and the step skew angle θe, and the maximum step skew angle θe that is equal to or less than the cogging torque ratio at the theoretical angle θs according to the magnetic characteristic (BH characteristic) of the stator core. The configuration of values is the same as in the first embodiment.

  12 and 13, the stator core is divided into an upper block 21a, a middle 21b, and a lower 21c, and the upper block 21a and the lower 21c and the middle are divided. The step skew is shifted in the opposite direction along the circumference of the block 21b, and the step skew angle θe is shifted from the reference line A in the opposite direction by shifting the blocks 21a and 21c and the block 21b, respectively. The angle θe is a theoretical angle represented by ½ of the theoretical angle θs with respect to the reduction of the cogging torque fundamental wave component.

  FIG. 14 shows a case where the ratio of the number of rotor magnetic poles to the number of stator magnetic poles is 2: 3. As shown in FIG. 14, the electrical angle is 15 ° (mechanical angle is 3.75 °). By doing so, the harmonic component of the cogging torque can be reduced. Note that the height of the upper block 21a and the lower block 21c is ½ that of the middle block 21b.

20 Stator, 21 Stator core, 21a Upper block,
21b Middle block, 21c Lower block, 22 Stator winding, 30 Rotor,
31 Rotor core, 32a upper permanent magnet, 32b lower permanent magnet.

Claims (4)

A rotor in which two stages of permanent magnets are provided in the axial direction on the outer peripheral surface of the rotor core, and the permanent magnets are shifted by a stage skew angle θe (electrical angle) in the circumferential direction of the rotor core between the two stages; A method of manufacturing a permanent magnet type rotating electrical machine including a stator having a cylindrical stator core provided with a stator winding in which the rotor is disposed and a rotating magnetic field for rotating the rotor is provided In
The lower limit of the step skew angle θe is the theoretical angle θs (electrical angle),
The upper limit value of the step skew angle θe is approximately 3/2 times the value of the theoretical angle θs,
A method of manufacturing a permanent magnet type rotating electrical machine, characterized in that the step skew angle θe is set to be larger than the lower limit and equal to or smaller than the upper limit.
However,
θs = (180 × rotor magnetic pole number / stator magnetic pole number and least common multiple of rotor magnetic pole number) / 2 (electrical angle) A rotor in which two stages of permanent magnets are provided in the axial direction on the outer peripheral surface of the rotor core, and the permanent magnets are shifted by a stage skew angle θe (electrical angle) in the circumferential direction of the rotor core between the two stages; A method of manufacturing a permanent magnet type rotating electrical machine including a stator having a cylindrical stator core provided with a stator winding in which the rotor is disposed and a rotating magnetic field for rotating the rotor is provided In
The relationship between the step skew angle and the cogging torque of the fundamental component of the cogging torque is obtained from the magnetic characteristics of the rotor core, and the cogging torque is greater than the cogging torque when the step skew angle is the theoretical angle θs (electrical angle). A method for manufacturing a permanent magnet type rotating electrical machine, wherein the step skew angle is set to be a step skew angle θe that becomes smaller.
However,
θs = (180 × rotor magnetic pole number / stator magnetic pole number and least common multiple of rotor magnetic pole number) / 2 (electrical angle) A rotor in which two stages of permanent magnets are provided in the axial direction on the outer peripheral surface of the rotor core, and the permanent magnets are shifted by a stage skew angle θe (electrical angle) in the circumferential direction of the rotor core between the two stages; In the permanent magnet type rotating electrical machine, comprising a stator having a cylindrical stator core provided with a stator winding that generates a rotating magnetic field for rotating the rotor.
The lower limit of the step skew angle θe is the theoretical angle θs (electrical angle),
The upper limit value of the step skew angle θe is approximately 3/2 times the value of the theoretical angle θs,
The step skew angle θe is set to be larger than the lower limit value and not more than the upper limit value,
Furthermore, the number of permanent magnets per stage provided on the outer peripheral surface of the rotor core is 4 × N (N is a natural number), and two permanent magnets adjacent in the circumferential direction are combined into a set of permanent magnet pairs. age,
From the state in which the 4 × N permanent magnets are uniformly arranged on the entire circumference of the outer peripheral surface, every other pair of the permanent magnet pairs is set to one of the theoretical angles θs on one side in the circumferential direction of the outer peripheral surface. Permanent magnet type rotating electrical machine characterized by being arranged in a / 2 shifted state.
However,
θs = (180 × rotor magnetic pole number / stator magnetic pole number and least common multiple of rotor magnetic pole number) / 2 (electrical angle) A rotor in which two stages of permanent magnets are provided in the axial direction on the outer peripheral surface of the rotor core, and the permanent magnets are shifted by a stage skew angle θe (electrical angle) in the circumferential direction of the rotor core between the two stages; In the permanent magnet type rotating electrical machine, comprising a stator having a cylindrical stator core provided with a stator winding that generates a rotating magnetic field for rotating the rotor.
The relationship between the step skew angle and the cogging torque of the fundamental component of the cogging torque is obtained from the magnetic characteristics of the rotor core, and the cogging torque is greater than the cogging torque when the step skew angle is the theoretical angle θs (electrical angle). Set the step skew angle to be smaller as the step skew angle θe,
Furthermore, the number of permanent magnets per stage provided on the outer peripheral surface of the rotor core is 4 × N (N is a natural number), and two permanent magnets adjacent in the circumferential direction are combined into a set of permanent magnet pairs. age,
From the state in which the 4 × N permanent magnets are uniformly arranged on the entire circumference of the outer peripheral surface, every other pair of the permanent magnet pairs is set to one of the theoretical angles θs on one side in the circumferential direction of the outer peripheral surface. Permanent magnet type rotating electrical machine characterized by being arranged in a / 2 shifted state.
However,
θs = (180 × rotor magnetic pole number / stator magnetic pole number and least common multiple of rotor magnetic pole number) / 2 (electrical angle)

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