JP2013207920A - Permanent magnet type rotary electrical machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a permanent magnet type rotary electrical machine that reduces a cogging torque generated by magnetic anisotropy of an electromagnetic steel sheet.SOLUTION: A permanent magnet type rotary electrical machine 1 includes: a rotor 4 having a plurality of magnetic poles formed by permanent magnets 2 and a rotor core 3; and a stator 5 having a toric yoke 8, teeth 9 that are protruded inside from the yoke 8 and provided in the circumference of the rotor 4, and stator windings 7 that are wound around slots 10 sectioned by the teeth 9. The yoke 8 and teeth 9 are integrally constituted by electromagnetic steel sheets laminated in the rotation axis direction of the rotor 4. The shape of the inside of the stator 5 has deformation of a fourth order mode against a complete round. The deformation of the fourth order mode is configured to be deformation such that the diameter of the inside of the stator 5 becomes small in the rolling direction of the electromagnetic steel sheet and the direction orthogonal thereto.

Description

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

  Permanent magnet type rotating electrical machines have the merit of being small and capable of generating high torque, but on the other hand, the pulsation of torque is caused by the interaction between the magnetic flux of the permanent magnet arranged on the rotor or stator and the magnetic pole of the electromagnetic steel plate. There is a demerit that it is likely to occur. In particular, the pulsating torque at no load is called cogging torque, which may cause rotational positioning accuracy and vibration noise.

  In a conventional permanent magnet type electric motor, a rotor having a plurality of magnetic poles and a rotor core made of permanent magnets is provided, and a plurality of slots 5 are provided along the circumferential direction. A stator core having a formed stator core and an armature winding wound in the slot, and the stator core formed integrally with the teeth and the yoke is provided with a tooth facing the rotor. An auxiliary groove is formed in the end surface of the tip portion along the axial direction, and this auxiliary groove is partially formed on the end surface of the tip portion of the tooth, and is a slot at the innermost diameter between adjacent teeth. The opening width is configured to be larger than the wire diameter of the armature winding. In the conventional permanent magnet type electric motor, the cogging torque is reduced by such a configuration.

JP2011-188865A

  In the method of reducing the cogging torque used in the conventional permanent magnet type electric motor, there is a frequency component of the cogging torque that cannot be reduced. Here, when the number of magnetic poles formed by the permanent magnet is N, the frequency component of the cogging torque generated when the rotor makes one rotation of the mechanical angle is referred to as the “N mountain component of the cogging torque”, and 2N peaks The frequency component of the generated cogging torque is referred to as “2N peak component of cogging torque”.

  For example, in the case of a permanent magnet type rotating electrical machine having 10 poles and 12 slots, assuming that the rotor is in an ideal state magnetically, the number of cogging torques generated when the rotor makes one mechanical angle is 10 and 12. It is the 60th mountain which is the least common multiple. The cogging torque component that can be reduced with the conventional configuration is the frequency component of the cogging torque in this ideal state. In an actual permanent magnet type rotating electrical machine, an N peak component and a 2N peak component of cogging torque are generated due to magnetic anisotropy of an electromagnetic steel sheet. For example, in the case of a permanent magnet type rotating electrical machine having 10 poles and 12 slots, 10 and 20 peaks are generated when the rotor makes one mechanical angle. Since these are lower-order than the frequency component of the cogging torque in the ideal state, they cannot be reduced by the conventional method of devising the shapes of the teeth and slots themselves.

  The present invention has been made to solve the above-described problems, and an object thereof is to reduce cogging torque generated by magnetic anisotropy of an electromagnetic steel sheet.

  In the permanent magnet type rotating electrical machine according to the present invention, a rotor having a plurality of magnetic poles formed by permanent magnets and a rotor core, an annular yoke, and projecting inwardly from the yoke around the rotor. And a stator having a stator winding wound around a slot defined in the teeth, and the yoke and the teeth are laminated in the direction of the rotation axis of the mover. The inner shape of the stator has a spatial fourth-order mode deformation with respect to a perfect circle, and the spatial fourth-order mode deformation depends on the rolling direction of the electrical steel sheet and the rolling. This is a deformation in which the inner diameter of the stator becomes smaller in a direction orthogonal to the direction.

  A permanent magnet type rotating electrical machine with reduced cogging torque caused by magnetic anisotropy of an electromagnetic steel sheet can be obtained.

It is sectional drawing of the permanent magnet type rotary electric machine which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the component of the direction of a rolling direction of the magnetomotive force of the electromagnetic steel plate which concerns on Embodiment 1 of this invention, and the component of a direction orthogonal to a rolling direction. It is sectional drawing of the conventional permanent magnet type rotary electric machine. It is explanatory drawing which shows radius R inside the stator which concerns on Embodiment 1 of this invention, and angle (theta) of this radius R and a rolling direction. It is explanatory drawing which shows the relationship between the radius R inside the stator which concerns on Embodiment 1 of this invention, and angle (theta). It is explanatory drawing which shows the waveform of the cogging torque of the permanent magnet type rotary electric machine which concerns on this Embodiment 1. FIG. It is explanatory drawing which shows the frequency component of the cogging torque of the permanent magnet type rotary electric machine which concerns on this Embodiment 1. FIG. It is sectional drawing which shows the modification of the stator core which concerns on Embodiment 1 of this invention. It is sectional drawing of the stator core which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the modification of the stator core which concerns on Embodiment 2 of this invention. It is sectional drawing of the stator core which concerns on this Embodiment 3. FIG. It is sectional drawing which shows the modification of the stator core which concerns on this Embodiment 3. FIG.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a permanent magnet type rotating electrical machine 1 according to Embodiment 1 of the present invention. In FIG. 1, a permanent magnet rotating electrical machine 1 includes a rotor 4 having a permanent magnet 2 and a rotor core 3 that form a plurality of magnetic poles, and a stator 5 provided around the rotor 4. Yes. As the permanent magnet 2, a ferrite magnet, a neodymium magnet, a samarium cobalt magnet, or the like is used.

  The stator 5 includes a stator core 6 and a stator winding 7. The stator core 6 has an annular yoke 8, teeth 9 projecting inwardly from the yoke 8 to surround the rotor 4, and slots 10 partitioned by the teeth 9. The stator winding 7 is wound around the slot 10. Further, the yoke 8 and the teeth 9 are made of electromagnetic steel plates stacked in the direction of the rotation axis of the rotor 4. As a method of forming such a laminated magnetic steel sheet stator core 6, first, the electromagnetic steel sheet is cut out into a stator core shape by press punching, and then, for example, caulking or bonding in a press die is performed. A method of fixing each steel plate by a method is used.

  A slight gap is provided between the rotor 4 and the stator 5 so that the rotor 4 and the stator 5 do not come into contact with each other and are not damaged. The permanent magnet type rotating electrical machine 1 has an interaction between a rotating magnetic field generated by passing an alternating current through the stator winding 7 in the stator 5 and a magnetomotive force generated by the permanent magnet 2 in the rotor 4. The rotor 4 rotates in synchronization with the rotating magnetic field to generate a rotational torque.

  In this embodiment, the number of permanent magnets 2 (number of magnetic poles) in the rotor 4 is 10, and the number of teeth 9 of the stator 5 is 12, but the combination of the number of magnetic poles and the number of teeth is It is not limited.

  Hereinafter, the cogging torque generated by the magnetic anisotropy of the electromagnetic steel sheet, which is the subject of the present invention, will be described with reference to FIG.

  FIG. 2 shows a locus of magnetomotive force with a constant magnetic flux density in each in-plane direction of the electrical steel sheet (direction perpendicular to the rotation axis of the rotor 4). In the same figure, when the rolling direction is θ = 0 ° (mechanical angle), the trajectories in the range of θ = 0-90 ° are shown for the cases where the magnetic flux densities B = 1.0T and B = 1.4T, respectively. ing. It is known that an electromagnetic steel sheet has anisotropy even if it is a steel sheet called a non-oriented steel sheet whose magnetic properties do not depend on the rolling direction. If it is assumed that there is no magnetic anisotropy, the locus of the magnetomotive force that makes the magnetic flux density constant is irrelevant to the rolling direction, and thus becomes a ¼ perfect circle centered on the origin in FIG. However, in an actual electrical steel sheet, the anisotropy of the spatial secondary mode (in the case of B = 1.0T in FIG. 2) and the spatial quaternary mode (in the case of B = 1.4T in FIG. 2) mainly. Have. In particular, the anisotropy of the spatial fourth-order mode is large.

  In FIG. 2, paying attention to the case of B = 1.4T in the spatial fourth-order mode, the magnetic properties in the rolling direction (θ = 0 °) and the direction perpendicular to the rolling direction (θ = 90 °) are good and constant. The magnetomotive force required to obtain the magnetic flux density is small, but the magnetic properties in the direction of θ = 30 to 60 ° with respect to the rolling direction are relatively poor, and the magnetomotive force required to obtain a constant magnetic flux density is large.

  As described above, the stator core 6 is formed by cutting and fixing each shape from a steel plate by a method such as press punching. For ease of manufacture, the stator core 6 is cut for each tooth 9 and each yoke 8. Without this, the stator core 6 may be formed by cutting all the teeth 9 and the annular yoke 8 together and fixing the cut steel plates without rotating them. In such a case, all the electromagnetic steel sheets constituting the stator core 6 have the rolling direction in the same direction. As a result, the magnetic flux interlinking in the stator 5 is strongly influenced by the magnetic anisotropy of the magnetic steel sheet, and a portion having a large magnetic permeability and a portion having a small magnetic permeability are generated depending on the portion in the rolling direction. As a result, the N peak and 2N peak components of the cogging torque are generated.

  In the example of this embodiment, in the permanent magnet type rotating electrical machine 1 with 10 poles and 12 slots, when there is a spatial fourth-order mode component in the anisotropy of the electrical steel sheet, the least common multiple of 10 poles and 4 mode numbers is used. There are 20 peaks of cogging torque components. An object of the present invention is to reduce a component resulting from such magnetic anisotropy of cogging torque.

  For explanation of the present invention, FIG. 3 shows a conventional permanent magnet type rotating electric machine for comparison, and FIG. 4 shows a stator core 6 according to the first embodiment. As shown in FIGS. 3 and 4, in the conventional permanent magnet type rotating electrical machine, the inner shape of the stator 5 is a perfect circle, whereas according to the first embodiment of the present invention, the stator core 6 The inner shape (equal to the inner shape of the stator 5) has a spatial fourth-order mode deformation at a specific mechanical angle θ (phase). Note that the deformation of the spatial fourth-order mode is that the deformation is repeated four times while θ changes from 0 to 360 °.

  More specifically, as shown in FIG. 4, the inner radius R of the stator core 6 (equal to the inner radius R of the stator 5) is shown in relation to the angle θ with the rolling direction of the magnetic steel sheet. In this case, as shown in FIG. 5, in the first embodiment, R is minimum at θ = 0 °, 90 °, 180 °, 270 °, and θ = 45 °, 135 °, 225 °, 315 °. In this configuration, R is maximized. Thus, by making the inner shape of the stator 5 into the shape shown in FIG. 4, the size of the gap between the stator 5 and the rotor 4 changes in the spatial fourth-order mode in the circumferential direction, and is fixed. The suction force between the rotor 5 and the rotor 4 changes in the space quaternary mode in the circumferential direction. As a result, the cogging torque component caused by the spatial fourth order mode of magnetic anisotropy of the electrical steel sheet and the spatial fourth order mode component of the attractive force cancel each other, so that the cogging torque component caused by the magnetic anisotropy of the cogging torque Can be reduced.

  In FIG. 6, in the 10 pole 12 slot permanent magnet rotating electrical machine 1, the cogging torque of the permanent magnet rotating electrical machine 1 in which the inner shape of the stator 5 is a conventional perfect circle and the inner shape of the stator 5 are changed. The cogging torque waveforms of the permanent magnet type rotating electrical machine 1 to which the spatial quaternary mode deformation of the present invention is applied are compared and shown. In the drawing, the horizontal axis represents the rotation angle θ ′ expressed in electrical angle, and the vertical axis represents the magnitude of the cogging torque. FIG. 7 shows the result of analyzing the cogging torque of FIG. 6 for each frequency (number of cogging torque peaks in one electrical angle cycle). In the permanent magnet type rotating electrical machine 1 with 10 poles and 12 slots, the cogging torque of 20 peaks which is the least common multiple of the mode order 4 and the pole number 10 due to the magnetic anisotropy of the spatial fourth order mode of the magnetic steel sheet, that is, 2N peaks 6 and 7, it can be seen that the 2N peak component of the cogging torque is reduced by applying the deformation of the spatial fourth-order mode of the present invention to the shape inside the stator 5. .

  4 shows a shape in which the slot 10a of the stator core 6 is disposed at a position that coincides with the rolling direction of the electromagnetic steel sheet, but it is not necessary to be limited to this. For example, as in the modification shown in FIG. 8, any of the slots 10 of the stator core 6 may have a shape that does not coincide with the rolling direction of the electrical steel sheet, and the direction orthogonal to the rolling direction of the electrical steel sheet. The same applies to. Regardless of the slot shape of the stator core 6 and the shape of the teeth 10, the 2N peak component of the cogging torque can be particularly reduced by applying the inner shape of the stator core 6 shown in FIG. 4.

  As described above, in the permanent magnet type rotating electrical machine 1 according to the present invention, the rotor 4 having the plurality of magnetic poles formed by the permanent magnet 2 and the rotor core 3, the annular yoke 8, and the inner side from the yoke 8. And a stator 5 having a stator winding 7 wound around a slot 10 defined in the tooth 9, and a yoke 8 and a tooth 9. , And integrally formed by electromagnetic steel plates laminated in the direction of the rotation axis of the mover 4, and the inner shape of the stator 5 has a deformation of a spatial fourth-order mode with respect to a perfect circle, and the spatial fourth-order Since the deformation of the mode is such that the inner diameter of the stator 5 becomes smaller in the rolling direction of the electrical steel sheet and in the direction orthogonal to the rolling direction, the cogging torque generated by the magnetic anisotropy of the electrical steel sheet It is possible to obtain the effect that it is possible to obtain a permanent magnet type rotary electric machine 1 having reduced.

Embodiment 2. FIG.
FIG. 9 is a sectional view of a stator core 6 according to Embodiment 2 of the present invention. In this embodiment, by providing the grooves 11 on the inner surface of the teeth 9b excluding the rolling direction of the electrical steel sheet and the teeth 9a positioned in the direction orthogonal to the rolling direction, the above-described spatial quaternary mode is deformed. Forming. More specifically, the teeth 9a not provided with the grooves 11 have a substantially smaller inner diameter by the depth of the grooves 11 than the teeth 9b provided with the grooves 11. That is, by providing the groove 11, the inner shape of the stator 5 has a spatial fourth-order mode deformation with respect to a perfect circle, and the spatial fourth-order mode deformation depends on the rolling direction of the electrical steel sheet and the deformation. In the direction orthogonal to the rolling direction, the inner diameter of the stator core 6 (corresponding to the inner diameter of the stator 5) can be reduced.

  By configuring in this way, the same effect as in the first embodiment can be obtained. Furthermore, in this embodiment, since it is only necessary to add the groove 11 to the stator core 6 whose inner shape is substantially circular, even if the magnetic properties of the electromagnetic steel sheet to be used are changed, the teeth provided with the groove 11 are provided. By appropriately designing the number and position, and the number, arrangement and depth of the grooves 11 in each tooth 9b, a desired low cogging torque permanent magnet type rotating electrical machine can be easily obtained.

  FIG. 9 shows the shape in which the slot 10a of the stator core 6 is disposed at a position coinciding with the rolling direction of the electromagnetic steel sheet, but it is not necessary to be limited to this. For example, as in the modification shown in FIG. 10, any slot 10 of the stator core 6 may have a shape that does not coincide with the rolling direction of the electromagnetic steel sheet, and is a direction orthogonal to the rolling direction of the electromagnetic steel sheet. The same applies to. Regardless of the slot shape of the stator core 6 and the shape of the teeth 10, the 2N peak component of the cogging torque can be particularly reduced by appropriately providing the groove 11 shown in FIG.

  As described above, in the permanent magnet type rotating electrical machine 1 according to the present invention, the grooves 11 are formed on the inner surface of at least some of the teeth 9b excluding the teeth 9a positioned in the rolling direction of the electromagnetic steel sheet and the direction orthogonal to the rolling direction. It is possible to obtain the effect that the permanent magnet type rotating electrical machine 1 in which the deformation of the spatial fourth-order mode can be formed and the cogging torque generated by the magnetic anisotropy of the electromagnetic steel sheet is reduced can be obtained. Can do.

Embodiment 3 FIG.
FIG. 11 is a sectional view of a stator core 6 according to Embodiment 3 of the present invention. In this embodiment, the radial direction length of the teeth 9c located in the rolling direction of the electrical steel sheet and the direction orthogonal to the rolling direction is made longer than the teeth 9d other than the teeth 9c, so that Forming a deformation. By configuring in this way, the same effect as in the first embodiment can be obtained.

  FIG. 11 shows a shape in which the slot 10a of the stator core 6 is disposed at a position that coincides with the rolling direction of the electromagnetic steel sheet, but it is not necessary to be limited to this. For example, as in the modification shown in FIG. 12, any of the slots 10 of the stator core 6 may have a shape that does not coincide with the rolling direction of the electrical steel sheet, and the direction orthogonal to the rolling direction of the electrical steel sheet. The same applies to. Regardless of the slot shape of the stator core 6 and the shape of the teeth 10, as shown in FIG. 11, the 2N peak component of the cogging torque can be particularly reduced by appropriately configuring the length of each tooth 9. it can.

  As described above, in the permanent magnet type rotating electrical machine 1 according to the present invention, the radial direction length of the teeth 9c positioned in the rolling direction of the electrical steel sheet and the direction orthogonal to the rolling direction is longer than the teeth 9d other than the teeth 9c. By doing so, it is possible to form a spatial quaternary mode deformation, and to obtain the effect of obtaining the permanent magnet type rotating electrical machine 1 in which the cogging torque generated by the magnetic anisotropy of the electromagnetic steel sheet is reduced. it can.

  1, 4, and 8 to 12, the number of the teeth 9 and the slots 10 is twelve, but these may be arbitrary numbers.

  DESCRIPTION OF SYMBOLS 1 Permanent magnet type rotary electric machine, 2 Permanent magnet, 3 Rotor iron core, 4 Rotor, 5 Stator, 6 Stator iron core, 7 Stator winding, 8 Yoke, 9, 9a, 9b, 9c, 9d Teeth, 10 10a slot.

Claims (3)

A plurality of magnetic poles formed by permanent magnets, and a rotor having a rotor core;
An annular yoke, a tooth projecting inwardly from the yoke and provided around the rotor, and a stator having a stator winding wound around a slot defined in the tooth;
The yoke and the teeth are integrally formed of electromagnetic steel plates stacked in the direction of the rotation axis of the rotor,
The inner shape of the stator has a spatial fourth-order mode deformation with respect to a perfect circle,
The deformation in the space quaternary mode is a deformation in which the inner diameter of the stator is reduced in the rolling direction of the electromagnetic steel sheet and the direction orthogonal to the rolling direction.   It is characterized in that the deformation of the spatial fourth-order mode is formed by providing grooves on the inner surface of at least some of the teeth except for the rolling direction of the electrical steel sheet and the teeth positioned in the direction orthogonal to the rolling direction. The permanent magnet type rotating electrical machine according to claim 1.   The radial direction length of the teeth located in the rolling direction of the electrical steel sheet and the direction orthogonal to the rolling direction is made longer than the teeth other than the teeth, thereby forming a spatial quaternary mode deformation. The permanent magnet type rotating electrical machine according to claim 1.

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