JP2017011858A - Rotary electric machine, magnet, and manufacturing method for magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make magnetization and demagnetization among all magnetic poles, formed in a rotor, uniform even in a case where one magnetic pole is composed using a plurality of permanent magnets of different holding powers.SOLUTION: A magnetic pole of a rotor is formed from a magnet unit formed in such a manner that a plurality of permanent magnets of different holding powers are superposed in a radial direction of a rotor. At least two permanent magnets of the plurality of permanent magnets are low-holding-power magnets having holding powers that can be magnetized or demagnetized by a magnetic field generated by a d-axis electric current flowing in a fixed coil. The permanent magnet having the highest holding power among the plurality of permanent magnets is disposed nearest to the air gap. The thickness of each low-holding-power magnet in a radial direction of the rotor is adjusted such that the equivalent holding power obtained by combining the respective holding powers of the low-holding-power magnets composing the magnet unit are substantially identical in all the magnet units provided in the rotor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotating electrical machine, a magnet, and a method for manufacturing a magnet.

  Conventionally, there has been known a rotor structure in which two permanent magnets having different holding forces are magnetically arranged in series to form one magnetic pole, and a plurality of the magnetic poles are arranged in the rotor (patent) Reference 1). By using this structure, the permanent magnet can be magnetized or demagnetized by the stator winding current during operation of the rotating electrical machine.

JP 2010-004671 A

  There is inherent variation in the retention of permanent magnets. The amount of this variation is a relatively small value with respect to the holding force of a permanent magnet used in a general rotating electric machine, and thus has not been a big problem. However, in the configuration in which the permanent magnet is magnetized or demagnetized by the stator winding current during operation of the rotating electrical machine, if there is a variation in coercive force characteristics between the magnetic poles in the rotor, the magnetization or demagnetization will occur. Can be involved. Variations in magnetization and demagnetization cause a problem that increases torque ripple and loss of the rotating electrical machine, which is a problem.

  An object of the present invention is to provide a technique for forming a single permanent magnet having a desired holding force by using a plurality of permanent magnets having different holding forces. In addition, by forming the magnetic poles of the rotor included in the rotating electric machine with the formed permanent magnet having a desired holding force, the magnetization and demagnetization between all the magnetic poles formed in the rotor can be made uniform. Provide technology that can.

  A magnet of a rotating electrical machine according to the present invention includes a stator having a stator winding for generating a rotating magnetic field, and a rotor having a plurality of magnetic poles and disposed via an air gap between the stator and the stator. Prepare. The magnetic pole of the rotor is formed by a magnet unit formed by superposing a plurality of permanent magnets having different holding forces in the radial direction of the rotor, and at least two of the plurality of permanent magnets are stator windings. The low-retention-force magnet having a holding force that can be magnetized and demagnetized by the magnetic field formed by the d-axis current flowing through the permanent magnet having the highest holding force among the plurality of permanent magnets is the most in the air gap. Located on the near side. The thickness in the rotor radial direction of each of the low holding force magnets is substantially the same in all magnet units in which the equivalent holding force obtained by combining the holding forces of the low holding force magnets constituting the magnet unit is provided in the rotor. It is adjusted to become.

  According to the present invention, the magnetic poles of the rotor are formed by the permanent magnet unit adjusted to have a desired holding force, so that the magnetization and demagnetization between all the magnetic poles formed in the rotor are uniform. Can be. Thereby, even if it is a case where one magnetic pole is comprised using several permanent magnets from which holding force differs, the risk that the torque ripple and loss of a rotary electric machine increase can be avoided.

FIG. 1 is a configuration diagram of the rotating electrical machine according to the first embodiment viewed from a plane perpendicular to the axial direction, and shows a part of the overall configuration. FIG. 2 is a diagram illustrating an example of magnetic characteristics of the low coercive force magnet. FIG. 3 is a diagram for explaining a method of calculating the equivalent holding force Hc_eq. FIG. 4A is a configuration diagram of the rotating electrical machine of Example 1 according to the first embodiment when viewed from a plane perpendicular to the axial direction. FIG. 4B is a diagram illustrating an equivalent holding force of the magnet unit and a holding force of the low holding force magnet with respect to a desired equivalent holding force according to the first embodiment. FIG. 5A is a configuration diagram of the rotating electrical machine of Example 2 according to the first embodiment when viewed from a plane perpendicular to the axial direction. FIG. 5B is a diagram illustrating the equivalent holding force of the magnet unit and the holding force of the low holding force magnet with respect to a desired equivalent holding force according to the second embodiment. FIG. 6A is a configuration diagram of the rotating electrical machine of Example 3 according to the first embodiment when viewed from a plane perpendicular to the axial direction. FIG. 6B is a diagram illustrating an equivalent holding force of the magnet unit and a holding force of the low holding force magnet with respect to a desired equivalent holding force according to the third embodiment. FIG. 7A is a configuration diagram of the rotating electrical machine of Example 4 according to the first embodiment when viewed from a plane perpendicular to the axial direction. FIG. 7B is a diagram illustrating an equivalent holding force of the magnet unit and a holding force of the low holding force magnet with respect to a desired equivalent holding force according to the fourth embodiment. FIG. 8A is a configuration diagram of the rotating electrical machine of Example 5 according to the first embodiment when viewed from a plane perpendicular to the axial direction. FIG. 8B is a diagram illustrating an equivalent holding force of the magnet unit and a holding force of the low holding force magnet with respect to a desired equivalent holding force according to the fifth embodiment. FIG. 8C is a diagram illustrating an equivalent holding force of the magnet unit and a holding force of the low holding force magnet with respect to a desired equivalent holding force according to the fifth embodiment. FIG. 9A is a perspective view showing a part of the rotating electrical machine of the second embodiment. It is a figure for demonstrating the detail of the magnet unit inserted by the rotor shown in FIG. 9B. FIG. 10 is a configuration diagram of the rotating electrical machine according to the third embodiment when viewed from a plane perpendicular to the axial direction.

[First embodiment]
FIG. 1 is a configuration diagram of the rotating electrical machine 100 according to the first embodiment viewed from a cross section perpendicular to the axial direction, and shows a part of the overall configuration. The rotating electrical machine 100 of the present embodiment includes an annular stator 3, a rotor 4 that is concentric with the stator 3, and is disposed so as to have an air gap 11 between the stator 3, A permanent magnet unit 10 (hereinafter simply referred to as a magnet unit) fitted in a corresponding portion of the rotor 4 in a state where the permanent magnets 1a and 1b are superposed in series in the magnetization direction. Configure the machine.

  The stator 3 includes a ring-shaped stator core 13, a plurality of teeth 9 protruding from the stator core 13 toward the inner peripheral side, and a stator winding 12 wound around the teeth 9. The stator core 13 is made of, for example, an electromagnetic steel plate that is a soft magnetic material.

  The rotor 4 has a rotor core 14. The rotor core 14 is formed in a cylindrical shape by a so-called laminated steel plate structure in which a large number of electromagnetic steel plates formed by punching a metal plate having a high magnetic permeability into an annular shape are laminated in the axial direction. ing. Further, in the vicinity of the peripheral portion of the rotor core 14 facing the stator 13, the magnetic poles constituted by the magnet units 10 are arranged at equal intervals along the circumferential direction, and the polarities of the magnetic poles adjacent to each other are the same. It is provided to have different polarities. Note that the rotor core 14 according to the rotating electrical machine 100 of the present embodiment has a six-pole structure in which six permanent magnets are provided along the circumferential direction as inferred from the partial configuration shown in FIG.

  Further, the rotor 4 has magnetic barriers 5 and 6 that are space portions formed by punching a magnetic steel sheet forming the rotor core 14 between the magnetic poles. The magnetic barriers 5 and 6 have a larger magnetic resistance than the magnetic steel sheet. Therefore, the magnetic barriers 5 and 6 act as magnetic flux barriers against the magnet magnetic flux in the magnetic circuit formed by the permanent magnets 1a and 1b on the rotor 4. As shown in the figure, the magnetic barrier 5 is formed in a substantially semicircular shape having a narrower width on the rotation center side than on the outer periphery side of the rotor 4. The magnetic barrier 6 is formed in a substantially U shape so as to cover the magnetic barrier 5 closer to the center of rotation than the magnetic barrier 5. However, the shape of the magnetic barriers 5 and 6 is not limited to this.

  Further, the magnetic barriers 5 and 6 are formed in the rotor 4 as shown in the figure, so that the magnetic flux emitted from the magnet unit 10 constituting one magnetic pole is constituted by the other adjacent magnet unit 10. A magnetic flux bypass path 7 is formed as a path for leakage to the magnetic pole side. Further, the rotor 4 is provided with a narrow bridge-shaped portion 8 connected to the magnetic flux bypass path 7 on the outer peripheral side of the magnetic barrier 5.

  The magnet unit 10 is fixed to the rotor core 14 by being fitted into a gap formed in a corresponding portion of the rotor core 14 in a state where the permanent magnets 1a and 1b are superposed so as to be magnetically in series. . In the rotating electrical machine 100, the radial direction of the rotor 4 is the magnetization direction. The permanent magnets 1a and 1b can be obtained, for example, by cutting a plurality of permanent magnet blocks, in which the holding force varies in the manufacturing process of the permanent magnet, to a desired thickness in each magnetization direction. Here, in the present embodiment, a position that is electrically orthogonal to the d-axis that is the geometric center of the magnet unit 10 is defined as the q-axis. In addition, since the rotary electric machine 100 of this embodiment has a 6-pole structure, a position at a mechanical angle of 30 degrees from the d axis is defined as the q axis.

  The permanent magnets 1a and 1b constituting the magnet unit 10 are magnetic fields (armature reaction magnetic fields) formed by passing a pulsed d-axis current through the stator winding 12 when the rotating electrical machine 100 is mounted on a vehicle. Therefore, the permanent magnet is a low-retention-force permanent magnet having a retention force enough to be magnetized or demagnetized.

  Here, the magnetic characteristics of the permanent magnets 1a and 1b constituting the magnet unit 10 will be described with reference to FIG. As described above, the permanent magnets 1a and 1b are permanent magnets having a holding force that can be magnetized or demagnetized by a magnetic field created by a pulsed d-axis current that is passed through the stator winding 12 (hereinafter, referred to as “permanent magnets”). Also called a low holding force magnet). FIG. 2 is a diagram showing an example of the magnetic characteristics of such a low coercive force magnet. In FIG. 2, the vertical axis represents the magnetic flux density (T) of the permanent magnet, and the horizontal axis represents the strength (A / m) of the magnetic field formed by the d-axis current of the stator winding 12. As the value of the d-axis current increases in the positive direction, the magnetic field applied to the permanent magnet becomes stronger, and the magnetic flux density of the permanent magnet increases accordingly.

  As shown in FIG. 2, the magnetic characteristics of the low coercive force permanent magnet are irreversible characteristics, and a plurality of magnetization paths are selected according to the magnitude of the d-axis current supplied to the stator winding 12. For example, it has c1-c4.

  By increasing the value of the d-axis current supplied to the stator winding 12 in the positive direction, the low coercive force magnet is magnetized so that its magnetic flux density increases. That is, the low coercive force magnet is magnetized by increasing the height of the d-axis current pulse supplied to the stator winding 12 in the positive direction.

When magnetizing the low coercive force magnet, one path is selected from the magnetization paths c1 to c4 depending on the height of the d-axis current pulse. For example, when the magnetic field generated by the d-axis current of the stator winding 12 is set to be the magnetizing magnetic field H _i1 , the magnetization path c1 is selected. Thereafter, in the selected magnetization path c1, the magnetic flux density (T) of the permanent magnet varies according to a negative d-axis current given by so-called field weakening control that reduces the field magnetic flux of the stator winding 12.

  On the other hand, when the value of the d-axis current supplied to the stator winding 12 is increased in the negative direction, the permanent magnet is magnetized so that the magnetic flux density decreases. That is, the permanent magnet is demagnetized by lowering the height of the pulse of the d-axis current supplied to the stator winding 12 in the negative direction.

When demagnetizing a permanent magnet having a low holding force, the d-axis current supplied to the stator winding 12 is set to be smaller than the negative d-axis current value obtained by field weakening control. For example, when the magnetic field generated by the d-axis current of the stator winding 12 is set to be the demagnetizing magnetic field H _r , the magnetic flux density of the stator winding 12 becomes zero. Note that the smaller the magnetic flux density of the permanent magnet, the smaller the back electromotive force acting on the stator winding 12.

  As described above, the permanent magnet having a low holding force gradually increases the magnetic flux density of the permanent magnet according to the height of the pulse of the d-axis current supplied to the stator winding 12 during the rotation of the rotating electrical machine 100. It can be increased or decreased. That is, the amount of magnetization of the low coercive force magnet can be changed stepwise by the d-axis current supplied to the stator winding 12.

  Thus, for example, when the rotating electrical machine 100 including the low coercive force magnet having such characteristics is applied to an electric vehicle, the d-axis current supplied to the stator winding 12 is controlled while the vehicle is traveling. Thereby, the magnetic force of permanent magnet 1a, 1b can be changed suitably according to the running state of an electric vehicle. Specifically, for example, in the low rotation region where torque is required, the torque and the output are magnetized so as to be maximized, and in the high rotation region where the rotation speed is required, the occurrence of back electromotive force is suppressed. For example, demagnetization is performed to increase the rotational speed. Further, since the efficiency can be improved over a wide range by changing the magnetic force of the permanent magnet according to the running state, the power consumption of the rotating electrical machine 100 can be suppressed.

  Note that the rotating electrical machine having such a low holding force magnet, that is, the rotating electrical machine 100 of the present embodiment has the characteristics that can change the magnetic force of the permanent magnet as described above, and therefore, the variable magnetic motor, variable It is called a magnetic flux motor. Hereinafter, the property related to the ease and difficulty of magnetization and demagnetization of the permanent magnet is referred to as magnetization and demagnetization.

  Here, in general, the holding force Hc of the low holding force magnet as described above is about 0 kA / m to 250 kA / m. The magnetization and demagnetization of the permanent magnet for a certain d-axis current vary depending on the holding force Hc of the permanent magnet. For example, when the holding force Hc is lower than a predetermined value, demagnetization is easily performed. Then, since the current in the field weakening control needs to be limited to such an extent that the permanent magnet is not demagnetized, field weakening is reduced. As a result, the induced voltage increases and the power decreases. On the other hand, when the holding force Hc is higher than a predetermined value, magnetization is difficult. For this reason, the amount of magnetization is insufficient, and the magnetic flux density is reduced, so that the torque is reduced.

  Accordingly, in the configuration in which the permanent magnet is magnetized or demagnetized by the stator winding current during the operation of the rotating electrical machine 100 as in the rotating electrical machine 100 according to the present invention, each magnetic pole of the rotor is configured. When the holding force Hc of the permanent magnets varies, the magnetization and demagnetization of the permanent magnets vary depending on the variation. This variation is a variation in the magnetic flux density between the magnetic poles in the rotor, which causes an increase in torque ripple that causes vibration and an increase in loss. Therefore, it is desirable that the permanent magnet used for the rotating electrical machine is uniform with a desired holding force Hc. However, it is practically difficult to suppress the variation in the holding force Hc generated in the manufacturing process of the permanent magnet to zero.

  In the manufacturing process of the permanent magnet used for the rotating electrical machine, even if the holding force Hc of the low holding force magnet varies, the permanent magnet is effectively used to make the rotor on the rotor of the rotating electrical machine. It is an object to make the magnetization and demagnetization uniform between the magnetic poles formed on the substrate.

  Returning to FIG. 1, the description will be continued. As shown in FIG. 1, the magnetic pole of the rotating electrical machine 100 according to the first embodiment is formed by a magnet unit 10 formed by superposing permanent magnets 1a and 1b so as to be magnetically in series. Therefore, even if the holding force Hc of the permanent magnets 1a and 1b constituting the magnet unit 10 included in the rotor 4 is non-uniform, the combined force obtained by combining the holding force Hc of the permanent magnet 1a and the holding force Hc of the permanent magnet 1b. The equivalent holding force Hc_eq that is a holding force may be uniform among all the magnetic poles formed on the rotor 4. Hereinafter, a method for calculating the equivalent holding force Hc_eq will be described.

  FIG. 3 is a diagram for explaining a method of calculating the equivalent holding force Hc_eq. In the upper part of the figure, the permanent magnets 1a and 1b are magnetically stacked in series. As a premise, the holding force Hc1 and thickness t1 of the permanent magnet 1a are different from the holding force Hc2 and thickness t2 of the permanent magnet 1b. Then, when the two permanent magnets 1a and 1b having different thicknesses t and holding forces Hc are overlapped and viewed as a single equivalent magnet (magnet unit 10), the apparent holding force Hc of the magnet unit 10 is The equivalent holding force Hc_eq is expressed by the following equation (1).

  That is, by adjusting the thickness t1 of the permanent magnet 1a and the thickness t2 of the permanent magnet 1b, a desired equivalent holding force Hc_eq can be obtained regardless of the values of the holding forces Hc1 and Hc2 of the permanent magnets 1a and 1b. it can.

  Here, the manufacturing method of the magnet unit 10 will be summarized. The magnet unit 10 cuts, for example, a plurality of permanent magnet blocks having different holding forces caused by manufacturing variations in the magnet manufacturing process into predetermined thicknesses t1 and t2 in the magnetization direction of the permanent magnet blocks. Then, the permanent magnets 1a and 1b having different holding forces respectively cut to the thicknesses t1 and t2 are overlapped so as to be in series with the magnetization direction. The predetermined thicknesses t1 and t2 are expressed by the above formula (1) so that the equivalent holding force obtained by combining the holding forces of the permanent magnets 1a and 1b constituting the magnet unit 10 becomes a desired equivalent holding force Hc_eq. Adjusted based on.

  By forming all the magnetic poles on the rotor 4 by the magnet unit 10 having the equivalent holding force Hc_eq adjusted in this way, the equivalents in all the magnetic poles can be obtained regardless of variations in the holding force Hc of the permanent magnets 1a and 1b. The holding force can be made substantially the same. Thereby, the magnetization and demagnetization between the magnetic poles are made uniform, so that the unbalance of the magnetization amount in each magnetic pole can be eliminated. Therefore, it is possible to suppress an increase in torque ripple and an increase in loss caused by an imbalance in the amount of magnetization between the magnetic poles. In addition, said substantially identical is within ± 10%, for example.

  Then, with reference to FIGS. 4-8, the aspect at the time of applying the magnet unit 10 manufactured as mentioned above to the rotary electric machine 100, and the equivalent holding force obtained are demonstrated.

[Example 1]
FIG. 4A is a configuration diagram of the rotating electrical machine 100 of Example 1 according to the first embodiment when viewed from a plane perpendicular to the axial direction, and configures the magnet unit 10 fitted to the rotor 4 and the magnet unit 10. It is a figure for demonstrating the aspect of the low holding power magnet 1a, 1b to do.

  4B shows an equivalent holding force (solid line) of the magnet unit 10 with respect to a desired equivalent holding force Hc_target (dotted line) according to the first embodiment and each holding force Hc of the low holding force magnets 1a and 1b (Hc_1a: one-dot chain line, Hc_1b: It is a figure showing a dashed-two dotted line). The vertical axis represents the magnetic flux density J [T], and the horizontal axis represents the magnetic field strength H [kA / m] formed by the d-axis current of the stator winding 12.

  As shown in FIG. 4B, the desired equivalent holding force Hc_target in the present embodiment is 160 [kA / m]. On the other hand, the holding force of the permanent magnet 1a is 224 [kA / m], and the holding force of the permanent magnet 1b is 97 [kA / m]. Since the radial width of the magnet insertion hole of the rotor 4 is set to about 10 mm, the thickness in the rotor radial direction (magnetization direction thickness) of the magnet unit 10 is set to 10 mm. Therefore, the sum of the thickness t1 of the permanent magnet 1a and the thickness t2 of the permanent magnet 1b is 10 mm. If the thicknesses t1 and t2 of the permanent magnets 1a and 1b are calculated based on the above formula (1) on the premise of this, t1 = 5 mm and t2 = 5 mm. Based on the calculation results, the thicknesses t1 and t2 of the permanent magnets 1a and 1b are adjusted to constitute the magnet unit 10, so that the magnet unit 10 can be obtained with a desired equivalent holding force Hc_target as shown by a solid line in the figure. Almost the same equivalent holding force 160 [kA / m] can be obtained.

  4A, when the magnet unit 1 is fitted to the rotor 4, the permanent magnet 1a having a higher holding force among the permanent magnets 1a and 1b is disposed on the side closest to the air gap 11. . The side closer to the air gap 11, that is, the outer peripheral side of the rotor 4 is easily affected by the magnetic field formed in the stator winding 12, so there is a possibility that unintended magnetization and demagnetization may be performed. Further, as described above, the permanent magnet has a property that magnetization and demagnetization are easier as the holding force is lower. Therefore, the risk of unintended magnetization or demagnetization can be suppressed by arranging permanent magnets having higher holding power on the outer peripheral side of the rotor 4.

  Moreover, as can be seen from FIG. 4B, the magnet unit 10 is configured by combining the permanent magnet 1a having a holding force Hc larger than the desired equivalent holding force Hc_target and the 1b having a holding force smaller than the desired equivalent holding force Hc_target. Thus, the magnet unit 10 having the desired equivalent holding force Hc_eq can be created.

[Example 2]
FIG. 5A is a configuration diagram of the rotating electrical machine 100 of Example 2 according to the first embodiment when viewed from a plane perpendicular to the axial direction, and configures the magnet unit 10 fitted to the rotor 4 and the magnet unit 10. It is a figure for demonstrating the aspect of permanent magnet 1a, 1b to do.

  FIG. 5B shows an equivalent holding force (solid line) of the magnet unit 10 with respect to a desired equivalent holding force Hc_target (dotted line) according to the second embodiment and each holding force Hc of the permanent magnets 1a and 1b (Hc_1a: one-dot chain line, Hc_1b: two points) FIG. The vertical axis represents the magnetic flux density J [T], and the horizontal axis represents the magnetic field strength H [kA / m] formed by the d-axis current of the stator winding 12.

  As shown in FIG. 5B, also in this embodiment, the desired equivalent holding force Hc_target is set to 160 [kA / m]. On the other hand, the holding force of the permanent magnet 1a is 192 [kA / m], and the holding force of the permanent magnet 1b is 128 [kA / m]. The magnetization direction thickness of the magnet unit 10 is set to 10 mm. Therefore, the sum of the thickness t1 of the permanent magnet 1a and the thickness t2 of the permanent magnet 1b is 10 mm. If the thicknesses t1 and t2 of the permanent magnets 1a and 1b are calculated based on the above formula (1) on the premise of this, t1 = 5 mm and t2 = 5 mm. By adjusting the thicknesses of the permanent magnets 1a and 1b as described above, an equivalent holding force 160 [kA / m] substantially the same as the desired equivalent holding force Hc_target can be obtained as shown by the solid line in the figure.

  Also in this embodiment, for the same reason as in the first embodiment, a low holding force magnet 1 a having a higher holding force is arranged on the outer peripheral side of the rotor 4.

[Example 3]
FIG. 6A is a configuration diagram of the rotating electrical machine 100 of Example 3 according to the first embodiment when viewed from a plane perpendicular to the axial direction, and configures the magnet unit 10 fitted to the rotor 4 and the magnet unit 10. It is a figure for demonstrating the aspect of permanent magnet 1a, 1b to do.

  FIG. 6B shows an equivalent holding force (solid line) of the magnet unit 10 with respect to a desired equivalent holding force Hc_target (dotted line) according to the third embodiment and each holding force Hc of the permanent magnets 1a and 1b (Hc_1a: one-dot chain line, Hc_1b: two points) FIG. The vertical axis represents the magnetic flux density J [T], and the horizontal axis represents the magnetic field strength H [kA / m] formed by the d-axis current of the stator winding 12.

  As shown in FIG. 6B, the desired equivalent holding force Hc_target is 160 [kA / m] as in the other embodiments. On the other hand, the holding force of the permanent magnet 1a is 223 [kA / m], and the holding force of the permanent magnet 1b is 143 [kA / m]. The magnetization direction thickness of the magnet unit 10 is set to 10 mm. Therefore, the sum of the thickness t1 of the permanent magnet 1a and the thickness t2 of the permanent magnet 1b is 10 mm. If the thicknesses t1 and t2 of the permanent magnets 1a and 1b are calculated based on the above formula (1) on the assumption of this, t1 = 2 mm and t2 = 8 mm are obtained. By adjusting the thicknesses of the permanent magnets 1a and 1b as described above, an equivalent holding force 160 [kA / m] substantially the same as the desired equivalent holding force Hc_target can be obtained as shown by the solid line in the figure.

  Also in this embodiment, the permanent magnet 1 a having a higher holding force is disposed on the outer peripheral side of the rotor 4 for the same reason as in the first and second embodiments.

[Example 4]
FIG. 7A is a configuration diagram of the rotating electrical machine 100 of Example 4 according to the first embodiment when viewed from a plane perpendicular to the axial direction, and configures the magnet unit 10 fitted to the rotor 4 and the magnet unit 10. It is a figure for demonstrating the aspect of permanent magnet 1a, 1b to do.

  FIG. 7B shows an equivalent holding force (solid line) of the magnet unit 10 with respect to a desired equivalent holding force Hc_target (dotted line) according to the fourth embodiment and each holding force Hc of the permanent magnets 1a and 1b (Hc_1a: one-dot chain line, Hc_1b: two points) FIG. The vertical axis represents the magnetic flux density J [T], and the horizontal axis represents the magnetic field strength H [kA / m] formed by the d-axis current of the stator winding 12.

  As shown in FIG. 7B, the desired equivalent holding force Hc_target is 160 [kA / m] as in the other embodiments. On the other hand, the holding force of the permanent magnet 1a is 183 [kA / m], and the holding force of the permanent magnet 1b is 88 [kA / m]. The magnetization direction thickness of the magnet unit 10 is set to 10 mm. Therefore, the sum of the thickness t1 of the permanent magnet 1a and the thickness t2 of the permanent magnet 1b is 10 mm. If the thicknesses t1 and t2 of the permanent magnets 1a and 1b are calculated based on the above formula (1) based on this assumption, t1 = 7.5 mm and t2 = 2.5 mm. By adjusting the thicknesses of the permanent magnets 1a and 1b as described above, an equivalent holding force 160 [kA / m] substantially the same as the desired equivalent holding force Hc_target can be obtained as shown by the solid line in the figure.

  Also in this embodiment, for the same reason as in the first to third embodiments, the permanent magnet 1 a having a higher holding force is disposed on the outer peripheral side of the rotor 4.

[Example 5]
FIG. 8A is a configuration diagram of the rotating electrical machine 100 of Example 5 according to the first embodiment when viewed from a plane perpendicular to the axial direction, and includes magnet units 10a and 10b and a magnet unit 10a fitted to the rotor 4. 10b is a diagram for explaining aspects of the permanent magnets 1a and 1d and the permanent magnets 1c and 1b that respectively constitute 10b. In this embodiment, the holding forces of the permanent magnets 1a to 1d are all different.

  FIG. 8B shows an equivalent holding force (solid line) of the magnet unit 10a with respect to a desired equivalent holding force Hc_target (dotted line) according to the fifth embodiment and each holding force Hc of the permanent magnets 1a and 1b (Hc_1a: one-dot chain line, Hc_1b: two points) FIG. The vertical axis represents the magnetic flux density J [T], and the horizontal axis represents the magnetic field strength H [kA / m] formed by the d-axis current of the stator winding 12.

  As shown in FIG. 8B, the desired equivalent holding force Hc_target is 160 [kA / m] as in the other embodiments. On the other hand, the holding force of the permanent magnet 1a is 223 [kA / m], and the holding force of the permanent magnet 1b is 144 [kA / m]. When the thicknesses t1 and t2 of the permanent magnets 1a and 1b are calculated based on the above formula (1) as in the other embodiments, t1 = 2 mm and t2 = 8 mm. By adjusting the thicknesses of the permanent magnets 1a and 1b as described above, an equivalent holding force 160 [kA / m] substantially the same as the desired equivalent holding force Hc_target can be obtained as shown by the solid line in the figure.

  FIG. 8C shows an equivalent holding force (solid line) of the magnet unit 10b with respect to a desired equivalent holding force Hc_target (dotted line) according to the fifth embodiment and each holding force Hc of the permanent magnets 1c and 1d (Hc_1a: one-dot chain line, Hc_1b: two points) FIG. The vertical axis represents the magnetic flux density J [T], and the horizontal axis represents the magnetic field strength H [kA / m] formed by the d-axis current of the stator winding 12.

  Further, as shown in FIG. 7C, the desired equivalent holding force Hc_target is 160 [kA / m] as in the other embodiments. On the other hand, the holding force of the permanent magnet 1c is 183 [kA / m], and the holding force of the permanent magnet 1d is 88 [kA / m]. When the thicknesses t1 and t2 of the permanent magnets 1a and 1b are calculated based on the above formula (1), t3 = 7.5 mm and t4 = 2.5 mm. By adjusting the thicknesses of the permanent magnets 1a and 1b as described above, an equivalent holding force 160 [kA / m] substantially the same as the desired equivalent holding force Hc_target can be obtained as shown by the solid line in the figure.

  In the present embodiment, the magnet units 10a and 10b have the same magnetization direction thickness, but the thicknesses t1 and t2 of the permanent magnets 1a and 1b constituting the magnet unit 10a and the permanent magnet 1c constituting the magnet unit 10b, The thicknesses t3 and t4 of 1d are different from each other.

  Thus, although the magnetization direction thickness which is the sum total of the thickness of each low coercive force magnet which comprises each magnet unit 10a, 10b is set substantially the same, the magnetization direction thickness of each said low coercive force magnet differs. May be. In this case, low magnetic force magnets having various holding forces can be used to form the magnet units 10a and 10b having a desired equivalent holding force at each magnetic pole on the rotor 4. Thereby, in the manufacture of the rotating electrical machine 100, it is possible to further tolerate the variation in holding force that occurs in the magnet manufacturing process.

  In the present embodiment, permanent magnets 1 a and 1 c having higher holding power are arranged on the outer peripheral side of the rotor 4 for the same reason as in the first to fourth embodiments.

  As described above, in the description according to the first to fifth embodiments, the example in which one magnet unit is configured by two low holding force magnets has been described. However, the number of low coercive force magnets constituting one magnet unit is not limited to this, and may be three or more. In that case, a magnet unit having a desired equivalent coercive force can be provided by calculating the respective magnetization direction thicknesses of the low coercive force magnets constituting the magnet unit using the following formula (2).

  Where Hc_ep represents a desired equivalent holding force, ti is the magnetization direction thickness of the i-th low holding force magnet counted from the outer peripheral side or the rotation center side of the rotor 4, and Hc_i is the i-th low holding force magnet. Represents the holding power. Further, i is an integer from 1 to N, and N is the total number of low coercive force magnets constituting the magnet unit.

  As described above, the rotary electric machine 100 according to the first embodiment includes the stator 3 having the stator winding 12 for generating the rotating magnetic field and the stator 3 having the plurality of magnetic poles via the air gap 11. And a rotor 4 to be arranged. The magnetic pole of the rotor 4 is formed by a magnet unit 10 formed by superposing a plurality of permanent magnets 1a and 1b having different holding forces in the radial direction of the rotor 4, and at least two permanent magnets 1a among the plurality of permanent magnets. Reference numeral 1b denotes a low coercive force magnet having a coercive force that can be magnetized and demagnetized by a magnetic field formed by a d-axis current flowing in the stator winding 12, and has the highest coercive force among a plurality of permanent magnets. The permanent magnet 1 a having the same is disposed on the side closest to the air gap 12. The rotor 4 is provided with an equivalent holding force Hc_eq obtained by synthesizing the holding forces Hc of the low holding force magnets constituting the magnet unit 10 in the rotor radial thickness (magnetization direction thickness) of each of the low holding force magnets. Adjustment is made so that all the magnet units 10 are substantially the same.

  Thereby, the magnetization and demagnetization between the magnetic poles are made uniform, so that the unbalance of the magnetization amount in each magnetic pole can be eliminated. Therefore, it is possible to suppress an increase in torque ripple and an increase in loss caused by an imbalance in the amount of magnetization between the magnetic poles.

  Moreover, the risk of unintended magnetization or demagnetization can be suppressed by arranging permanent magnets having higher holding power on the outer peripheral side of the rotor 4.

  In the rotating electrical machine 100 according to the first embodiment, the low holding force magnet 1a among the low holding force magnets 1a and 1b constituting the magnet unit 10 has a holding force larger than the desired equivalent holding force Hc_target, and is low. The holding force magnet 1b has a holding force smaller than a desired equivalent holding force Hc_target. Thereby, the magnet unit 10 having the desired equivalent holding force Hc_eq can be created.

  The rotating electrical machine 100 according to the first embodiment is a case where the magnet unit 10 includes N low holding force magnets, and the equivalent holding force is Hc_ep, and among the N low holding force magnets, the rotor 4 Of the n low holding force magnets when the thickness of the i-th low holding force magnet is ti and the holding force of the i-th low holding force magnet is Hc_i. Each thickness ti is adjusted so that the above equation (2) is satisfied with respect to a desired equivalent holding force Hc_ep. Thereby, even if it is a case where a magnet unit is comprised with three or more low holding power magnets, the magnet unit which has the desired equivalent holding force Hc_eq can be created.

  In the rotating electrical machine 100 according to the first embodiment, all the magnet units 10 included in the rotor 4 have substantially the same thickness in the rotor radial direction, and the low holding force magnets 1a and 1b constituting the magnet unit 10 are substantially the same. The thickness in the rotor radial direction may be different in each magnet unit 10 provided in the rotor 4. Thereby, in order to constitute the magnet unit 10 having a desired equivalent holding force, low holding force magnets having more various holding forces can be used. Thereby, in the manufacture of the rotating electrical machine 100, it is possible to further tolerate the variation in holding force that occurs in the magnet manufacturing process.

[Second Embodiment]
Next, the rotary electric machine 100 of 2nd Embodiment is demonstrated.

  FIG. 9A is a perspective view of a cross section perpendicular to the axial direction of the rotating electrical machine 100 of the second embodiment, and shows a part of the entire configuration. FIG. 9B is a view for explaining an aspect of the magnet unit 10 fitted to the rotor 4 shown in FIG. 9A, and is a view of the magnet unit 10 viewed from the axial side surface of the rotor 4.

  As can be seen from FIG. 9B, the magnet unit 10 forming one magnetic pole of the rotating electrical machine 100 of the second embodiment rotates the magnet subunits 30a, 30b, and 30c formed by superimposing the low coercive force magnets in the rotor radial direction. Stacked in the direction of the child axis.

  The magnet subunit 30a is configured by superimposing low coercive force magnets 1a and 1b in the rotor radial direction. Further, the thicknesses t_1a and t_1b of the low holding force magnets 1a and 1b are determined by the above equation (1) based on the holding forces Hc_1a and Hc_1b of the low holding force magnets 1a and 1b. It is adjusted to become power. For each of the low coercive force magnets b1, b2 and c1, c2 constituting the other magnet subunits 30b, 30c, the above equation (1) is established so that the magnet subunits 30b, 30c each have a desired equivalent holding force. Based on this, the magnetization direction thickness is adjusted.

  The magnet unit 10 is configured by stacking magnet subunits 30 a, 30 b, 30 c having substantially the same equivalent holding force in the axial direction of the rotor 4. The magnet unit 10 configured as described above has the same desired equivalent holding force as each of the magnet subunits 30a, 30b, and 30c. In addition, each magnet subunit 30a, 30b, 30c is comprised by arrange | positioning the low holding power magnet which has higher holding power among the low holding power magnets which comprise these in the side nearest to the air gap 11. FIG.

  By forming one magnetic pole with the magnet unit 10 configured in this way, a low holding force magnet having various holding forces can be used to form a magnet unit having a desired equivalent holding force. . Thereby, in the manufacture of the rotating electrical machine 100, it is possible to further tolerate the variation in holding force that occurs in the magnet manufacturing process.

  As described above, the magnetic pole included in the rotating electrical machine 100 of the second embodiment is a magnet subunit 30a in which a plurality of permanent magnets 1a, 1b, 1c, 1d, 1e, and 1f having different holding forces are overlapped in the radial direction of the rotor. , 30b, 30c are formed by a magnet unit 30 configured by stacking three in the axial direction of the rotor. Thereby, in the manufacture of the rotating electrical machine 100, it is possible to further tolerate the variation in holding force that occurs in the magnet manufacturing process.

[Third embodiment]
Next, the rotary electric machine 100 of 3rd Embodiment is demonstrated.

  FIG. 10 is a configuration diagram of the rotating electrical machine 100 of Example 1 according to the third embodiment when viewed from a plane perpendicular to the axial direction, and illustrates an aspect of the magnet unit 10 fitted to the rotor 4. FIG.

  As shown in the drawing, the magnet unit 10 of the present embodiment is configured by superposing three permanent magnets of two low holding force magnets 40b and 40c and one high holding force magnet 40a in the rotor radial direction. It is characterized by that. Of the three permanent magnets 40 a, 40 b, and 40 c, the high holding force magnet 40 a having the highest holding force is disposed on the side closest to the air gap 11.

  Here, the high coercive force magnet is a permanent magnet having such a high coercive force that it is not magnetized or demagnetized depending on the magnetic field generated by the pulsed d-axis current passed through the stator winding 12. That means. Such a holding force is, for example, 500 [kA / m] or more. The equivalent holding force, which is the combined holding force with the low holding force magnets 40b and 40c, is adjusted so that the equivalent holding force is about 160 [kA / m] based on the above equation (1). And

  With such an arrangement, it is possible to support magnetization and demagnetization due to the equivalent holding force of the low holding force magnets 40b and 40c by the high holding force of the high holding force magnet 40a. Further, by arranging the high coercive force magnet 40c on the side closest to the air gap 11, unintended magnetization or demagnetization is caused by the magnetic field generated by the pulsed d-axis current energized in the stator winding 12. Risks that are made can be avoided. Further, when the magnet unit 10 is manufactured, a high holding force having a high holding force can be obtained even if the target holding combined force of the magnet unit 10 cannot be reached only by the equivalent holding force of the low holding force magnets 40b and 40c. By using the force magnet, the combined holding force of the entire magnet unit 10 may reach the target. That is, by using a high holding force magnet, it is possible to utilize a low holding force magnet that is biased toward a lower side, and thus it is possible to tolerate manufacturing variations of the low holding force magnet. In addition, the magnet unit 10 in this embodiment also adjusts the magnetization direction thickness of all the permanent magnets including a high coercive force magnet based on said Formula (2), and produces the magnet unit 10 of desired coercive force. be able to.

  As described above, in the rotating electrical machine 100 of the third embodiment, at least one permanent magnet among the plurality of permanent magnets constituting the magnet unit 10 is a high holding force magnet having a holding force higher than that of the low holding force magnet. Therefore, even when the holding force of the low holding force magnets 40b and 40c is so small that it cannot reach the holding force assumed at the time of design, the high holding force of the high holding force magnet 40a brings it close to the desired combined holding force. Can do.

  The present invention is not limited to the embodiment described above. For example, the application destination of the magnet unit 10 adjusted to a desired holding force is not limited to the rotating electric machine as described above, but is an acoustic device such as a speaker or a headphone, an advanced medical device such as MRI, various sensors using magnetic force, and the like. It can be applied to various devices using magnets.

DESCRIPTION OF SYMBOLS 1a, 1b ... Low coercive force magnet 3 ... Stator 4 ... Rotor 10 ... Magnet unit 11 ... Air gap 12 ... Stator winding 30a, 30b, 30c ... Magnet subunit 100 ... Rotating electric machine

Claims (8)

In a rotating electrical machine comprising a stator having a stator winding for generating a rotating magnetic field, and a rotor having a plurality of magnetic poles and being arranged through an air gap between the stator,
The magnetic pole is formed by a magnet unit formed by overlapping a plurality of permanent magnets having different holding forces in the radial direction of the rotor,
At least two permanent magnets among the plurality of permanent magnets are low coercive force magnets having a coercive force that can be magnetized and demagnetized by a magnetic field formed by a d-axis current flowing in the stator winding,
The permanent magnet having the highest holding force among the plurality of permanent magnets is disposed on the side closest to the air gap,
The thickness in the rotor radial direction of each of the low holding force magnets is the same in all the magnet units in which the equivalent holding force obtained by combining the holding forces of the low holding force magnets constituting the magnet unit is provided in the rotor. Adjusted to be approximately the same,
Rotating electric machine characterized by that. Among the low holding force magnets constituting the magnet unit, at least one of the low holding force magnets has a holding force larger than the equivalent holding force, and at least one other low holding force magnet is equivalent to the equivalent holding force. Having a holding force smaller than the holding force,
The rotating electrical machine according to claim 1. The magnet unit includes N low-retention-force magnets,
The equivalent holding force is Hc_ep,
Of the N low holding force magnets, the thickness of the i-th low holding force magnet counted from the outer peripheral side or the rotation center side of the rotor is ti, and the holding force of the i-th low holding force magnet is If Hc_i,
The thickness ti of each of the N low holding force magnets is adjusted so that the following expression (1) is established for a desired equivalent holding force Hc_ep.
The rotating electrical machine according to claim 1 or 2, characterized in that

The thickness in the rotor radial direction of all the magnet units provided in the rotor is substantially the same,
The thickness in the rotor radial direction of each low holding force magnet constituting the magnet unit is different in each of the magnet units provided in the rotor,
The rotating electrical machine according to any one of claims 1 to 3, wherein The magnetic pole is configured by stacking at least two magnet units in the axial direction of the rotor, in which a plurality of permanent magnets having different holding forces are stacked in the radial direction of the rotor,
The rotating electrical machine according to any one of claims 1 to 4, wherein Among the plurality of permanent magnets constituting the magnet unit, at least one of the permanent magnets is a high holding force magnet having a holding force higher than that of the low holding force magnet.
The rotating electrical machine according to any one of claims 1 to 5, wherein A plurality of permanent magnets having different holding forces are superposed so as to be in series with the magnetization direction of the permanent magnet,
The thickness in the magnetization direction of each of the permanent magnets is adjusted so that an equivalent holding force obtained by combining the holding forces of the permanent magnets constituting the magnet becomes a desired holding force.
A magnet characterized by that. A method for producing a magnet in which a plurality of permanent magnets having different holding forces are stacked in series with the magnetization direction of the permanent magnet,
Cutting a plurality of permanent magnet blocks having different holding forces into a predetermined thickness in the magnetization direction of the permanent magnet blocks;
A plurality of permanent magnets having different holding forces and overlapping each other in series with the magnetization direction of the permanent magnet to form one magnet, and
The predetermined thickness is adjusted so that an equivalent holding force obtained by combining holding forces of the permanent magnets constituting the magnet becomes a desired holding force.
A method for manufacturing a magnet.

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