JP2008005637A - Permanent magnet embedded electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily provide a small permanent magnet-embedded electric motor with low vibration, low noise, high output and high efficiency, which can be manufactured easily, without making the outside diameter of a rotor into a variant petal shape, since torque ripples can be reduced by the demand for low vibration and low noise, and in which man-hours will not increase, since a core will not skew. <P>SOLUTION: The electric motor is provided with a stator 2, where an annular yoke and a plurality of teeth are radially formed by leaving circumferential direction space to serve as a winding groove, and the rotor which is confronted with the stator 2 via a small gap and generates a magnetic field in a permanent magnet embedded in a rotor core which is held freely rotatably. A first rotor 3, where inverted arcuate magnets, projecting to a rotor center side and in a plate shape are arranged alternately, and a second rotor 6, where inverted arcuate magnets are arranged and laminated in the axial direction and constitute the rotor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor that is required to be small and highly efficient, such as a compressor, an electric vehicle, a hybrid vehicle, and a fuel cell vehicle, which require a small and highly efficient characteristic, particularly in an embedded permanent magnet electric motor.

  In recent years, awareness of coexistence with the global environment and energy saving has increased, and electric motors installed in electric devices such as compressors used in air conditioners and refrigerators, electric motors installed in electric vehicles, hybrid vehicles, fuel cell vehicles, etc. However, there is a demand for small size and high efficiency, and a magnet embedded motor or the like in which a magnet is arranged inside the rotor is often used. Further, there is a strong demand for low vibration and low noise, and it is important to reduce torque ripple for low vibration and low noise.

In the conventional example, a single part shape of the slit in the rotor provided for embedding the permanent magnet and a part of the outer diameter are linear (for example, refer to Patent Document 1), a stator core or a rotor core Is skewed (see, for example, Patent Document 2).
Japanese Patent Laying-Open No. 2004-320989 (page 9, FIG. 2) JP 2000-175380 (page 3, FIG. 1)

  FIG. 6 shows an example of a conventional permanent magnet embedded motor. 101 is a rotor core, 102 is a permanent magnet disposed in the groove of the rotor core, and 103 is a slit provided at the end of the rotor core magnetic pole. The outer shape of the rotor core is not a circle but a petal shape formed by connecting arcs having a radius R1 offset from the center of the maximum radius R by a1. Since the outer diameter of the rotor is not a circle but a petal shape, it is difficult to manufacture a punching die as compared to a circle, and it is difficult to ensure the accuracy of the rotor.

  FIG. 7 shows an example of a conventional permanent magnet embedded motor. (A) represents an example of a stator, 104 represents a stator core, and 105 represents a tooth. The stator core 104 is skewed by rotating the teeth 105 in the rotational direction. (B) represents a rotor, 106 represents a rotor core, and 107 represents a permanent magnet disposed in a groove of the rotor core 106. The skew is formed by rotating the magnetic poles in the rotational direction. Skewing has the effect of smoothing the switching of magnetic poles, and is effective in reducing vibration and noise. However, it is difficult to apply a high-occupancy winding to a skewed stator core, and stacking the same rotor core sheets makes the magnet shape complicated. When the magnet shape is simplified, different rotor core sheets are used. As a result, the assembly man-hours become complicated, which may lead to a decrease in reliability.

  The present invention solves such a conventional problem. The outer diameter of the rotor is circular and easy to manufacture, and since it does not skew, the number of man-hours is not increased and vibration is low, noise is small, and the size is small. An object of the present invention is to provide a permanent magnet embedded motor with high output and high efficiency.

In order to solve the above-described problems, the present invention provides a stator in which a plurality of teeth are radially formed with a circumferential interval between an annular yoke and a winding groove, and a small gap between the stator and the stator. In a motor including a rotor that generates a field with a permanent magnet embedded in a rotor core that is opposed to and rotatably supported, a reverse arc shape and a flat plate shape projecting toward the center of the rotor The rotor is configured by axially laminating the first rotor in which the magnets are alternately arranged and the second rotor in which the reverse arc magnet that is convex toward the center of the rotor is arranged. This is an embedded permanent magnet electric motor.

A stator in which a plurality of teeth are radially formed at circumferential intervals to be an annular yoke and a winding groove, and a rotation that is rotatably held facing the stator through a slight gap. In the electric motor having a rotor that generates a magnetic field by a permanent magnet embedded in the core of the core, a first rotor in which reverse arc-shaped and flat-plate-shaped magnets that are convex toward the center of the rotor are alternately arranged And a second rotor having a reverse arc magnet that protrudes toward the rotor center side in the axial direction to form a permanent magnet embedded type electric motor that constitutes a rotor. The torque pulsation of the second rotor and the torque pulsation of the second rotor are substantially reversed, so that the synthesized torque pulsation can be reduced, and a small, high-output and high-efficiency permanent magnet embedded motor can be provided.

  In the embodiment of the present invention, a stator in which a plurality of teeth are radially formed with a circumferential interval as an annular yoke and a winding groove is opposed to the stator via a slight gap. In a motor equipped with a rotor that generates a field with a permanent magnet embedded in a rotor core that is rotatably held, alternating arc-shaped and flat-plate magnets projecting toward the center of the rotor A permanent magnet embedded in which a rotor is configured by axially laminating a first rotor arranged in a rotor and a second rotor arranged with a reverse arc magnet projecting toward the center of the rotor. This is a built-in electric motor, and the synthesized torque pulsation can be reduced by roughly reversing the torque pulsation of the first rotor and the torque pulsation of the second rotor.

  The embodiment of the present invention is the embedded permanent magnet electric motor according to claim 1, wherein the thickness ratio of the first rotor and the second rotor is different. Synthetic torque pulsation can be further reduced.

  In addition to the first rotor and the second rotor, the embodiment of the present invention has a magnetic pole arrangement opposite to that of the first rotor and has a flat plate shape and a convex shape on the rotor center side. An embedded permanent magnet electric motor characterized in that a rotor is formed by laminating third rotors in which arc-shaped magnets are alternately arranged in the axial direction. Both N and S poles have a flat plate shape. Since the permanent magnet is composed of two types of permanent magnets, ie, a permanent magnet having a reverse arc shape, both poles can be magnetically balanced.

  The embodiment of the present invention is characterized in that the plate-shaped magnet is a magnet having a higher energy product than the reverse arc-shaped magnet that protrudes toward the center of the rotor. Each permanent magnet can be used by making a motor with a weak magnetic flux, for example, a magnetic flux that is concentrated, for example, a ferrite magnet that is concentrated and balanced with a strong magnetic flux, for example, a rare earth magnet. .

  The embodiment of the present invention is a permanent magnet embedded electric motor according to any one of claims 1 to 4, characterized in that a rotor core by powder sintering is used. The degree of freedom in shape increases, and the magnetic flux of the permanent magnet between the rotors can be optimally introduced into the stator core.

  Furthermore, the embodiments of the present invention are a compressor equipped with the permanent magnet embedded electric motor according to any one of claims 1 to 5, and further, an electric vehicle, a hybrid vehicle, and a fuel cell vehicle.

Embodiments of the present invention will be described below with reference to the drawings.
(Example 1)
FIG. 1 is a plan view of a permanent magnet embedded electric motor 1 showing a first embodiment of the present invention. The stator 2 is formed with a plurality of teeth radially at intervals in the circumferential direction that becomes an annular yoke and a winding groove.

  2A is a sectional view of the first rotor, FIG. 2B is a sectional view of the second rotor, and FIG. 2C is a side view of the rotor. In the first rotor 3, plate-shaped permanent magnets 4 (N poles) and reverse arc-shaped permanent magnets 5 (S poles) projecting toward the center of the rotor are alternately arranged inside the rotor. On the other hand, the second rotor 6 has a structure in which only a reverse arc-shaped permanent magnet 7 that protrudes toward the center of the rotor is disposed. Adjacent permanent magnets have different polarities and prevent magnetic flux that is short-circuited through the rotor core in the space 8 formed by grooves or holes. In FIG. 2C, the arrangement of the permanent magnets is schematically shown by a flat plate-shaped permanent magnet 4 by a broken line and a reverse arc-shaped permanent magnet 5 by a thick line. The N pole is composed of two types of a permanent magnet 4 having a flat plate shape and a permanent magnet 5 having a reverse arc shape, and the S pole is composed only of the permanent magnet 5 having a reverse arc shape.

  The torque characteristics of the rotor having this configuration will be described with reference to FIG. FIG. 3 shows the rotor electrical angle on the horizontal axis and the torque on the vertical axis. This motor is a three-phase six-pole motor, and has a torque pulsation of one cycle at an electrical angle of 20 degrees.

  ◇ indicates a torque waveform when the first rotor 3 is used alone. □ is a torque waveform when only the second rotation 6 is configured. The first rotor 3 has a generally downwardly convex graph, and the second rotor 6 has a generally upwardly convex graph. A triangle indicates the torque waveform of this embodiment, and it can be seen that the torque pulsation is greatly reduced.

  As described above, in this embodiment, torque pulsation can be easily achieved by stacking two types of rotors without changing the rotor outer diameter into a petal-like irregular shape or skewing the iron core. It is possible to provide a permanent magnet embedded type electric motor that can be greatly reduced, has low vibration, low noise, is small, has high output, and is highly efficient.

  In addition, by using a magnet having a higher energy product than the reverse arc-shaped magnet 5 for the plate-shaped permanent magnet 4, the magnetic flux of a weak magnetic flux, for example, a ferrite magnet is concentrated, and the balance with a strong magnetic flux, for example, a rare-earth magnet. By making the motor balanced, each permanent magnet can be utilized, and a low-cost, compact, high-output and highly efficient embedded permanent magnet motor can be provided. A magnet-embedded electric motor can be provided.

  In this embodiment, the reverse arc-shaped permanent magnet 5 inserted into the first rotor 3 and the reverse arc-shaped permanent magnet 7 inserted into the second rotor 6 are configured separately. , And may be configured integrally in the axial direction. The N pole and the S pole may be reversed. Although this embodiment is an example of a 6-pole interior magnet type electric motor, the same effect can be obtained even when the number of poles is different.

(Example 2)
In the first embodiment, an example in which torque pulsation can be further reduced by changing the lamination ratio of the first rotor 3 and the second rotor 6 will be described. FIG. 4 is a graph showing the lamination ratio of the first rotor 3 on the horizontal axis and the torque pulsation ratio of the permanent magnet embedded electric motor on the vertical axis. In addition, the torque pulsation of the structure where the lamination | stacking thickness of the 1st rotor 3 is the same as the 2nd rotor 6, ie, the lamination | stacking ratio of the 1st rotor 3 is 50% was set to 1.

  As apparent from FIG. 4, the configuration in which the lamination ratio of the first rotor 3 is 55% and the lamination ratio of the second rotor is 45% has the smallest torque pulsation, and the lamination of the first rotor 3 It is possible to reduce the ratio to 96% or less with respect to the configuration in which the ratio is 50%, which is more effective.

  As described above, in the present embodiment, the first rotor 3 and the second rotor 6 can be formed without changing the outer diameter of the rotor into a petal-like irregular shape or skewing the iron core. Torque pulsation can be easily reduced significantly by optimizing the lamination ratio of the two types of rotors, and a compact, high-power, high-efficiency permanent magnet embedded motor with low vibration and low noise is provided. be able to.

(Example 3)
The difference between the present embodiment and the first embodiment is that the configuration of the rotor is three stages. In addition to the first rotor 3 and the second rotor 6, a third rotor 9 is provided. A laminated structure is used. This will be described below with reference to FIG.

  5 (a), (b), (c), and (d) respectively show a cross section of the first rotor 3, a cross section of the second rotor 6, a cross section of the third rotor 9, and this embodiment. The side of the rotor is shown. As shown in FIG. 5A, the first rotor 3 is configured by alternately arranging flat permanent magnets 4 on the N poles and reverse arc-shaped permanent magnets 5 on the S poles. As shown in FIG. 5 (b), the second rotor 6 is configured by disposing permanent magnets 7 having an arcuate shape for both the N pole and the S pole. Further, as shown in FIG. 5 (c), the third rotor 9 has a reverse arc-shaped permanent magnet 10 for the N pole and a flat plate-shaped permanent magnet for the S pole, as opposed to the first rotor 3. The magnets 11 are arranged alternately. In FIG. 5 (d), regarding the arrangement of the permanent magnets, the plate-shaped permanent magnets 4 and 11 are schematically shown by broken lines, and the reverse arc-shaped permanent magnets 5, 7, and 10 are schematically shown by thick lines. Since both the N pole and the S pole are composed of two types of permanent magnets, a plate-shaped permanent magnet and a reverse arc-shaped permanent magnet, there is a feature that both poles are magnetically balanced. For example, when a plate-shaped magnet having an energy product higher than that of a reverse arc-shaped magnet is used, the magnetic flux of the N pole of the first rotor 3 is increased and partial magnetic saturation may occur. By increasing the magnetic flux of the south pole with the third rotor 9, there is an effect of making partial magnetic saturation difficult to occur. By using a motor that balances the magnetic flux concentration of, for example, a ferrite magnet with a weak magnetic flux and the balance with a strong magnetic flux, for example, a rare earth magnet, each permanent magnet can be used, and it is an inexpensive, compact, high-power, high-efficiency permanent magnet. An embedded electric motor can be provided, and a smaller, high-power and high-efficiency permanent magnet embedded electric motor can be provided.

  In addition, the use of a rotor core by powder sintering increases the degree of freedom in the shape of the rotor core, and the magnetic flux of the permanent magnet between the rotors can be optimally introduced into the stator core. It is possible to provide a permanent magnet embedded type electric motor that is highly efficient in output.

  In addition, by mounting the permanent magnet embedded electric motor of the present invention, it is possible to contribute to the reduction in size and efficiency of compressors, electric vehicles, hybrid vehicles, and fuel cell vehicles.

The present invention can realize a small, high-output, high-efficiency electric motor with a simple configuration, and thus is useful as a permanent magnet embedded electric motor for compressors, electric vehicles, hybrid vehicles, fuel cell vehicles, and the like.

The top view which shows the permanent magnet embedded type motor in one Example of this invention (A) is sectional drawing which shows the 1st rotor, (b) is sectional drawing which shows the 2nd rotor, (c) Side view which shows the same rotor Graph showing the same torque waveform Graph showing the torque pulsation ratio (A) is sectional drawing which shows the 1st rotor of the other Example of this invention, (b) is sectional drawing which shows the 2nd rotor, (c) is sectional drawing which shows the 3rd rotor. Figure, (d) is a side view showing the rotor Half sectional view showing a rotor of a conventional permanent magnet embedded motor A perspective view showing a rotor and a stator of a conventional permanent magnet embedded motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Embedded permanent magnet motor 2 Stator 3 1st rotor 4, 11 Flat permanent magnet 5, 7, 10 Reverse arc permanent magnet 6 2nd rotor 8 Space part 9 3rd rotor 101, 106 Rotor core 102, 107 Permanent magnet 103 Space part 104 Stator core 105 Stator teeth

Claims (7)

A stator in which a plurality of teeth are radially formed at circumferential intervals to be an annular yoke and a winding groove, and a rotation that is rotatably held facing the stator through a slight gap. In the electric motor having a rotor that generates a magnetic field by a permanent magnet embedded in the core of the core, a first rotor in which reverse arc-shaped and flat-plate-shaped magnets that are convex toward the center of the rotor are alternately arranged An embedded permanent magnet electric motor characterized in that a rotor is formed by laminating a second rotor on which a reverse arc magnet projecting toward the center side of the rotor is arranged in the axial direction. The permanent magnet embedded electric motor according to claim 1, wherein a thickness ratio of the first rotor and the second rotor is different. In addition to the first rotor and the second rotor, a plate shape and a reverse arc-shaped magnet that protrudes toward the rotor center side are alternately arranged with a magnetic pole arrangement opposite to the first rotor. An embedded permanent magnet electric motor characterized in that a rotor is formed by laminating three rotors in the axial direction. The embedded permanent magnet electric motor according to any one of claims 1 to 3, wherein the flat magnet is a magnet having a higher energy product than a reverse arc magnet having a convex shape toward the rotor center. The embedded permanent magnet electric motor according to any one of claims 1 to 4, wherein a rotor iron core by powder sintering is used. A compressor equipped with the interior permanent magnet motor according to any one of claims 1 to 5. An electric vehicle, a hybrid vehicle, and a fuel cell vehicle equipped with the permanent magnet embedded electric motor according to any one of claims 1 to 5.