JP6428586B2 - Rotating electric machine - Google Patents

Description

The present invention relates to a permanent magnet type rotating electrical machine.

In a permanent magnet type rotating electrical machine having a rotor having a conventional permanent magnet, due to the slots of the stator arranged opposite to the outer peripheral surface of the rotor core constituting the rotor, the rotor is rotated. The magnetic entrainment energy fluctuates, and as a result, a cogging torque that is a pulsation of torque is generated. This cogging torque hinders the smooth rotation of the rotor and causes noise and vibration, so it must be sufficiently reduced.

Conventionally, as a cogging torque reduction method in a permanent magnet type rotating electrical machine, a plurality of cogging compensators that can be moved independently in the axial direction are provided in the vicinity of the end surface of the permanent magnet in the axial direction, and the distance between adjacent cogging compensators is However, there has been proposed a method of arranging the rotor so that the relative angle with respect to the rotation axis of the rotor is (90 / P) degree + (360 m / P) degree. Here, P is the number of poles of the rotor, and m is an integer less than P (see, for example, Patent Document 1).

In addition, a conventional rotor includes a rotor core made of a magnetic material, a plurality of permanent magnets embedded in the rotor core, and a rotor cover that abuts against the end face of the rotor core. The permanent magnet type rotating electrical machine which reduces the cogging torque of the rotor by reducing the magnetic flux density of the permanent magnet guided by the stator by forming the leakage flux of each permanent magnet by the rotor cover. Has been proposed (see, for example, Patent Document 2).

Japanese Patent No. 4466275 (page 13, FIG. 1) Japanese Patent Laying-Open No. 2009-27768 (page 6, FIG. 1)

Since the conventional permanent magnet type rotating electric machine is configured as described above, in the structure in which a plurality of cogging compensators that are movable independently in the axial direction are disposed in the vicinity of the end surface on the axial direction side of the permanent magnet, There is a limit to the adjustment of the cogging torque, and there is a problem that the cogging torque cannot be sufficiently reduced.

In addition, since the outer shape of the rotor cover made of magnetic material in contact with the end face of the rotor core is arranged to be equal to the outer shape of the rotor core, the magnetic pulsation caused by the interaction between the magnet and the stator slot is a sine wave. There is a problem that the cogging torque cannot be sufficiently reduced. Furthermore, there is a problem that the moment of inertia increases due to an increase in the mass of the rotor cover.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a permanent magnet type rotating electrical machine that reduces cogging torque and reduces moment of inertia while eliminating the need for adjustment of cogging torque. It is to be.

The rotating electrical machine according to the present invention includes a stator having a slot, a rotor, and a permanent magnet inserted along the axial direction of the rotor. A plurality of protrusions that are different from the outer diameter shape and partially close the axial end of the permanent magnet are provided, and the outer periphery of the protrusion includes an adjustment iron core having a diameter that covers all the radial surfaces of the permanent magnet. .

In the present invention, since the adjustment iron core having a protrusion different from the outer diameter shape of the rotor is disposed at the axial end portion of the rotor, the cogging torque can be sufficiently reduced while making the adjustment of the cogging torque unnecessary. Stable power transmission can be realized under small torque fluctuations while ensuring high torque density, and high response can be ensured by reducing the moment of inertia.

It is sectional drawing of the rotary electric machine which shows Embodiment 1 of this invention. It is a perspective view which shows the cogging torque adjustment iron core of the rotary electric machine which shows Embodiment 1 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 1 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 1 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 1 of this invention. It is a figure which shows the magnetic flux density when not providing the cogging torque adjustment iron core of the rotary electric machine which shows Embodiment 1 of this invention. It is a figure which shows the magnetic flux density at the time of arrange | positioning the cogging torque adjustment iron core of the rotary electric machine which shows Embodiment 1 of this invention. It is a figure which shows the cogging torque waveform of the rotary electric machine which shows Embodiment 1 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 1 of this invention. It is a figure which shows the magnitude | size of the cogging torque of the rotary electric machine which shows Embodiment 1 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 2 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 3 of this invention. It is a perspective view of the rotor of the rotary electric machine which shows Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a sectional view of a rotating electrical machine showing Embodiment 1 of the present invention, and FIG. 2 is a perspective view showing a cogging torque adjusting iron core of the rotating electrical machine showing Embodiment 1 of the present invention. 3 to 5 are perspective views of the rotor of the rotating electrical machine showing Embodiment 1 of the present invention.

Inside the rotating electrical machine 1, there is a cylindrical rotor 3 into which a rotating shaft is inserted, and the rotor 3 is supported by a frame 7 at both ends of the shaft through brackets 9 by bearings 10. In addition, permanent magnets 6 are inserted into a plurality of openings provided along the circumferential direction of the rotor 3 and formed along the axial direction so that N poles and S poles are alternately arranged inside the rotor 3. And pasted. The stator 2 is disposed on the outer periphery of the rotor 3 through a minute gap. A coil 11 is accommodated in a slot 11 disposed on the inner peripheral side of the stator 2, and a current is passed through the coil 8, whereby a rotating magnetic field is formed in the stator 2, and the rotor 3 is synchronized with the rotating magnetic field. Rotates.

The stator core 4 constituting the stator 2 and the rotor core 5 constituting the rotor 3 are formed by laminating a plurality of electromagnetic steel plates in the rotation axis direction, but are formed from a dust core or the like. May be. Moreover, you may use various well-known things, such as what has a division | segmentation iron core structure and a thin connection core structure.

As shown in FIG. 4, the rotating electrical machine according to the first embodiment of the present invention has an opening in the slot 11 in the circumferential direction of the stator inner peripheral surface 12 of the stator 2 facing the outer peripheral surface of the rotor 3. Since the plurality of slot openings 13 and the teeth 14 constituting the stator 2 are alternately present, the permeability μ1 of the slot 13 and the permeability μ2 of the teeth 14 are alternately present. Thus, a magnetic permeability difference is alternately generated in the circumferential direction of the stator inner peripheral surface 12. The value of the magnetic permeability μ2 of the tooth portion 14 constituted by laminating electromagnetic steel sheets or the like is generally larger than the value of the magnetic permeability μ1 in the slot opening 13 determined by the air inside the slot 11 and the coil 8. 1000 times larger. For this reason, the magnetic flux generated from the rotor 3 passes through the tooth portion 14 instead of passing through the slot opening portion 13 having a large magnetic resistance. As a result, the magnetic flux is dense in the tooth portion 14 and in the slot opening portion 13. Coarse and a density distribution of the magnetic flux density B occurs along the circumferential direction.

The physical quantity obtained by B × B / μ is called magnetic entrainment energy. As the rotor 3 rotates, the magnetic entrainment energy at the center of the permanent magnet 6 fluctuates, and cogging torque that is a pulsation of torque is generated. This cogging torque is the number of times of the least common multiple of the number of slots 11 and the number of permanent magnets 6 for each rotation of the rotor 3 (6 permanent magnets 6 and 36 slots 11, that is, 6 poles and 36 slots). 36 times), and the period of the cogging torque is 10 ° (= 360 ° / 36) in mechanical angle. This cogging torque may cause positioning accuracy and vibration noise. In the magnet-embedded rotary electric machine in which the permanent magnet 6 is embedded in the rotor 3, the cogging torque is particularly large.

In order to reduce such cogging torque, in Embodiment 1 of the present invention, as shown in FIGS. 2 to 5, the rotor 3 is disposed at both ends in the axial direction of the rotor core 5 constituting the rotor 3. Unlike outer shape, a part in the circumferential direction central portion of the permanent magnet 6 inserted into a plurality of openings formed along the axial direction is provided along the circumferential direction of the rotor 3 infarction technique, the permanent magnet all six radial surface of infarction Guyo, adjusted as many projections 30 of the permanent magnet 6, the central portion direction of the permanent magnets 6 from the axial center, i.e., the cogging torque of the magnetic material having a d-axis direction Cogging torque adjusting iron cores 20, 20a, 20b, which are adjusting iron cores, are disposed.

6 is a diagram showing the magnetic flux density when the cogging torque adjusting iron core of the rotating electric machine according to the first embodiment of the present invention is not provided, and FIG. 7 is the cogging torque adjusting iron core of the rotating electric machine according to the first embodiment of the present invention. FIG. 8 is a diagram showing a cogging torque waveform of the rotating electrical machine according to the first embodiment of the present invention.

As shown in FIG. 7, by arranging the cogging torque adjusting iron cores 20a and 20b of the magnetic material with respect to the magnetic flux density 50 before arranging the cogging torque adjusting iron cores 20a and 20b, as shown in FIG. Magnetic flux at both axial ends of the rotor core 5 leaks toward the cogging torque adjusting iron cores 20a and 20b, and the magnetic flux density 51 decreases. The decrease in the magnetic flux density 51 generates an anti-phase component of the cogging torque, and the anti-phase component of the cogging torque acts in the direction of canceling the cogging torque that has existed conventionally. As described above, the cogging torque adjusting iron cores 20a and 20b having the same number of protrusions 30 as the number of the permanent magnets 6 in the d-axis direction so as to partially close the central portion in the circumferential direction of the permanent magnet 6 are disposed, and the rotor By reducing the magnetic flux density at both axial ends of the iron core 5, as shown in FIG. 8, the cogging torque 60 having a period determined by the least common multiple of the number of permanent magnets 6 and the number of slots 11 A new pole period cogging cogging torque 61 of opposite phase is generated.

The cogging cogging torque 61 having a new pole period with a reverse phase does not occur when the protrusion 30 does not block the permanent magnet 6 at all, or does not cover the entire surface of the permanent magnet 6, and part of the permanent magnet 6 is generated. It occurs for the first time when it is closed. At this time, the cogging torque 60 is canceled by the anti-phase cogging torque 61, and the cogging torque can be reduced by the difference of the cogging torque 61.

As described above, since the cogging torque adjusting iron cores 20a and 20b having the protrusions 30 different from the outer diameter shape of the rotor 3 are disposed at the axial end portion of the rotor 3, the adjustment of the cogging torque is unnecessary. Cogging torque can be sufficiently reduced, stable power transmission can be realized under small torque fluctuations while ensuring a high torque density, and a rotating electrical machine that can ensure high responsiveness by reducing the moment of inertia is made possible.

The axial thickness of the cogging torque adjusting iron cores 20a and 20b and the area of the protrusion 30 that partially closes the circumferential central portion of the permanent magnet 6, that is, the radial direction and the circumferential size, It can be changed depending on the shape and the product width, which is the laminated width of the rotor core 5, and is not limited to the first embodiment of the present invention.

In the first embodiment of the present invention, the cogging torque adjusting iron cores 20a and 20b are disposed at both axial ends of the rotor core 5, but are arranged only at one axial end of the rotor iron core 5. Even if installed, the effect of reducing the cogging torque can be obtained.

FIG. 9 is a perspective view of the rotor of the rotary electric machine showing the first embodiment of the present invention. The outer diameter of the rotor core 5, specifically, the diameter of the rotor core 5 in the d-axis direction is D, and the rotor. The product width of the iron core 5 is L. FIG. 10 is a diagram showing the magnitude of cogging torque of the rotating electrical machine according to the first embodiment of the present invention. As shown in FIG. 10, the effect of reducing the cogging torque is further increased by setting the relationship between the outer diameter D of the rotor core 5 and the product width L of the rotor core 5 to a range of D / L> 1.0. be able to.

As shown in FIG. 7, the cogging torque 60 having a period determined by the least common multiple of the number of permanent magnets 6 and the number of slots 11 and the cogging cogging torque 61 having a new anti-phase pole period are in the axial direction of the rotor core 5. Since it occurs only at both ends, when the product width L of the rotor core 5 is extremely long, the influence of the antiphase cogging torque 61 generated at both ends in the axial direction of the rotor core 5 on the entire product width L is limited. Therefore, the magnetic flux density at the central portion in the axial direction of the rotor core 5 cannot be sufficiently reduced only by arranging the cogging torque adjusting cores 20a and 20b at both axial ends of the rotor core 5. . Therefore, in order to obtain a sufficient cogging torque reduction effect, it is preferable to apply the present invention to a rotary electric machine having a structure in which the product width L of the rotor core 5 is short, for example, a thin rotary electric machine.

Embodiment 2. FIG.
In the first embodiment, the configuration in which the cogging torque adjusting iron cores 20, 20a, and 20b of the magnetic body provided with the protrusions 30 from the axial center to the circumferential central portion of the permanent magnet 6, that is, the d-axis direction has been described. , circumferential end portions infarction technique, radial surface of the permanent magnet 6 of the permanent magnets 6 inserted into a plurality of openings formed along the axial direction is provided along the circumferential direction of the rotor 3 all a busy Guyo, as many protrusions of the permanent magnet 6, the circumferential end portion boundary direction of the permanent magnets 6 from the axial center, that is possible to obtain the same effect by arranging the q-axis direction it can.

FIG. 11 is a perspective view of a rotor of a rotating electrical machine showing Embodiment 2 of the present invention. In the second embodiment, magnetic cogging torque adjusting iron cores 21 having protrusions 31 different from the outer diameter shape of the rotor 3 are disposed at both axial ends of the rotor iron core 5 constituting the rotor 3. However, unlike the first embodiment, the cogging torque adjusting iron core 21 having the same number of protrusions 31 as the number of the permanent magnets 6 is disposed in the q-axis direction of the rotor 3.

As a result, as in the first embodiment, the magnetic flux at the axial end of the rotor core 5 can be reduced, and the least common multiple of the number of slots 11 and the number of permanent magnets 6 as shown in FIG. And a cogging cogging torque 61 having a new anti-phase period, and a cogging torque 60 having a period determined by the least common multiple of the number of slots 11 and the number of permanent magnets 6, The cogging torque can be reduced by the difference between the cogging torques 61, which is offset by the torque 61. The cogging cogging torque 61 having a new pole period with a reverse phase does not occur in a state where the protrusion 31 does not block the permanent magnet 6 at all, or a state where the permanent magnet 6 is blocked over the entire surface. It occurs for the first time when it is closed.

As described above, since the cogging torque adjusting iron core 21 having the protrusion 31 different from the outer diameter shape of the rotor 3 is disposed at the axial end of the rotor 3, the cogging torque is not required to be adjusted. Can be sufficiently reduced, stable power transmission can be realized under small torque fluctuations while securing a high torque density, and further, a rotating electrical machine capable of ensuring high responsiveness by reducing the moment of inertia is made possible.

Embodiment 3 FIG.
In the first embodiment, the configuration in the case where the number of the protrusions 30 and the number of the permanent magnets 6 are the same has been described. However, a plurality of protrusions 30 are provided along the circumferential direction of the rotor 3 and formed along the axial direction. the circumferential direction central portion and the circumferential end of the permanent magnets 6 inserted into the opening portion busy technique, all the radial surface of the permanent magnet 6 busy Guyo projections unit, twice the number of the permanent magnets 6 Similar effects can be obtained even with the arrangement.

FIG. 12 is a perspective view of a rotor of a rotating electric machine showing Embodiment 3 of the present invention. In the first embodiment, the method of reducing the fundamental wave component of the cogging torque having a period determined by the least common multiple of the number of slots 11 and the number of permanent magnets 6 has been described. However, in the third embodiment, the number of permanent magnets 6 is reduced. By arranging the cogging torque adjusting iron core 22 having twice the protrusion 32, the second harmonic component of the cogging torque, which is a pulsation component twice the fundamental wave component of the cogging torque, can be reduced. In the third embodiment, the protrusions 32 have the same number of protrusions as the number of permanent magnets 6 in the d-axis direction of the rotor 3 and the same number of protrusions as the number of permanent magnets 6 in the q-axis direction of the rotor 3. Have.

When the cogging torque adjusting iron core 22 having the protrusions 32 that is twice the number of the permanent magnets 6 is disposed, 2 of the fundamental wave component of the cogging torque having a period determined by the least common multiple of the number of the slots 11 and the number of the permanent magnets 6. A cogging torque having an antiphase period which is a double pulsation component is generated. At this time, the cogging torque is canceled by the anti-phase cogging torque that is a pulsation component twice the fundamental wave component, and the cogging torque can be reduced by the difference of the cogging torque. Cogging cogging torque of a new pole period with a reverse phase does not occur when the projection 32 does not block the permanent magnet 6 at all, or when the permanent magnet 6 is blocked over the entire surface, and partially blocks the permanent magnet 6. It occurs for the first time when it is in the state of being.

As described above, since the cogging torque adjusting iron core 22 having the protrusion 32 different from the outer diameter shape of the rotor 3 is disposed at the axial end of the rotor 3, the cogging torque is not required to be adjusted. Can be sufficiently reduced, stable power transmission can be realized under small torque fluctuations while securing a high torque density, and further, a rotating electrical machine capable of ensuring high responsiveness by reducing the moment of inertia is made possible.

Embodiment 4
In the first embodiment, the configuration in which the number of the protrusions 30 and the number of the permanent magnets 6 are the same has been described. However, in the plurality of openings provided along the circumferential direction of the rotor 3 and formed along the axial direction. circumferential part fort skill of the inserted permanent magnet 6, all busy Guyo a protrusion in the radial direction of the surface of the permanent magnet 6, the same effect even in the configuration in which as many arranged slots 11 Can be obtained.

FIG. 13 is a perspective view of a rotor of a rotating electrical machine showing Embodiment 4 of the present invention. In the first to third embodiments, the method of reducing the fundamental wave component or the second harmonic component of the cogging torque having a period determined by the least common multiple of the number of slots 11 and the number of permanent magnets 6 has been described. In the fourth embodiment, by arranging the cogging torque adjusting iron cores 23 having the same number of protrusions 33 as the number of slots 11, harmonic components of the cogging torque generated by the stator 2 can be reduced.

When the cogging torque adjusting cores 23 having the same number of protrusions 33 as the number of slots 11 are disposed, the antiphase is a harmonic component of the cogging torque having a period determined by the least common multiple of the number of slots 11 and the number of permanent magnets 6. The cogging torque of the period is generated. At this time, the cogging torque is canceled out by the anti-phase cogging torque that is the pulsation component of the harmonic of the fundamental wave component, and the cogging torque can be reduced by the difference of the cogging torque. The cogging cogging torque of the new pole period with the opposite phase does not occur in a state where the projection 33 does not block the permanent magnet 6 at all, or a state where the permanent magnet 6 is blocked over the entire surface, and partially blocks the permanent magnet 6. It occurs for the first time when it is in the state of being.

As described above, since the cogging torque adjusting iron core 23 having the projection 33 different from the outer diameter shape of the rotor 3 is disposed at the axial end of the rotor 3, the cogging torque is not required to be adjusted. Can be sufficiently reduced, stable power transmission can be realized under small torque fluctuations while securing a high torque density, and further, a rotating electrical machine capable of ensuring high responsiveness by reducing the moment of inertia is made possible.

DESCRIPTION OF SYMBOLS 1 Rotating electric machine, 2 Stator, 3 Rotor, 4 Stator iron core, 5 Rotor iron core, 6 Permanent magnet, 7 Frame, 8 Coil, 9 Bracket, 10 Bearing, 11 Slot, 12 Stator inner peripheral surface, 13 Slot opening, 14 Tooth, 20, 20a, 20b, 21, 22, 23 Cogging torque adjusting iron core, 30, 31, 32, 33 Protrusion, 50, 51 Magnetic flux density, 60, 61 Cogging torque

Claims (8)

In a rotating electrical machine having a stator having a slot, a rotor, and a permanent magnet inserted along the axial direction of the rotor, an outer diameter shape of the rotor is formed at an axial end of the rotor. And a plurality of protrusions that partially block the axial end of the permanent magnet, and the outer periphery of the protrusion includes an adjusting iron core that has a diameter that covers all the radial surfaces of the permanent magnet. Rotating electric machine.
The rotating electrical machine according to claim 1, wherein the adjusting iron core is provided at both axial ends of the rotor. The rotating electrical machine according to claim 1, wherein the number of the protrusions is the same as the number of the permanent magnets. The rotating electrical machine according to any one of claims 1 to 3, wherein the protrusion is located at a circumferential center of the permanent magnet. The rotating electrical machine according to any one of claims 1 to 3, wherein the protrusion is located at a circumferential end of the permanent magnet. 3. The rotating electrical machine according to claim 1, wherein the protrusion has twice as many as the permanent magnet. The rotating electrical machine according to claim 6, wherein the protrusion is located at a circumferential center and a circumferential end of the permanent magnet. The rotating electrical machine according to claim 1, wherein the number of the protrusions is the same as the number of the slots.

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