Rotating electric machines

Abstract

To provide a self-starting low cost rotary electric machine.SOLUTION: A rotary electric machine 2 includes a stator 10 and a rotor 12 rotating with respect to the stator 10. The stator 10 includes windings 22, 24 for generating rotating magnetic fields of P and 2P poles. The rotor 12 has P magnetic salient poles arranged in the circumferential direction formed by the rotor core 30 thereof, and has 2P magnetic poles arranged in the circumferential direction. The rotor core 30 is a block rotor core.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine. [Background technology]

[0002] Self-starting rotating electric machines are known that combine the characteristics of induction motors and synchronous motors and can be started from a power source without using an inverter. Conventionally, rotating electric machines have been proposed in which the rotor has a squirrel-cage conductor and the rotor is started by passing an induced current through it (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-37126 [Patent Document 2] Japanese Patent Application Publication No. 10-336927 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional rotating electric machines, the rotor has a squirrel-cage conductor, making the rotor structure complex, which hinders reduction in the manufacturing costs of the rotor and, in turn, the rotating electric machine.

[0005] The present invention has been made in light of such a situation, and one exemplary purpose of an embodiment of the present invention is to provide a low-cost rotating electric machine that is self-starting. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention provides a rotating electric machine comprising a stator and a rotor that rotates relative to the stator. The stator includes windings for generating a rotating magnetic field with a P pole and two P poles. The rotor has P magnetic salient poles arranged circumferentially by its rotor core, and also has 2P magnetic poles arranged circumferentially. The rotor core is a solid rotor core.

[0007] Another aspect of the present invention is also a rotating electric machine. This rotating electric machine includes a stator and a rotor that rotates relative to the stator. The stator includes windings for generating a rotating magnetic field with a P pole and two P poles. The rotor includes a rotor core having an annular portion and P salient poles that extend from the annular portion and are arranged in a circumferential direction, and has 2P magnetic poles that are arranged in the circumferential direction. The annular portion is a lamination, and the salient poles are solid salient poles or laminations with fewer laminations than the annular portion.

[0008] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, devices, systems, etc., are also valid aspects of the present invention. [Effects of the Invention]

[0009] According to one aspect of the present invention, a low-cost self-starting rotating electric machine can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a rotating electrical machine system according to an embodiment; [Figure 2] FIG. 2 is a diagram showing the results of a simulation of the starting characteristics of the rotating electric machine of FIG. [Figure 3] 2 is a diagram showing the results of a simulation of torque change with respect to the rotation speed of the rotating electric machine of FIG. 1. FIG. [Figure 4] FIG. 10 is a schematic diagram of a rotary electric machine system according to a modified example. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6]FIG. 10 is a schematic diagram of a rotating electrical machine system according to another modified example. [Figure 7] FIG. 10 is a cross-sectional view of a rotor for a rotating electric machine according to yet another modified example. [Figure 8] 8(a) and 8(b) are cross-sectional views of a rotating electrical machine including the rotor of FIG. [Figure 9] FIG. 10 is a cross-sectional view of a rotating electric machine 202 according to yet another modified example. [Figure 10] FIG. 10 is a view of the rotor of FIG. 9 as seen in the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, identical or equivalent components and members shown in each drawing will be assigned the same reference numerals, and duplicate explanations will be omitted where appropriate. Furthermore, the dimensions of the members in each drawing will be enlarged or reduced as appropriate for ease of understanding. Furthermore, some members that are not important for explaining the embodiments will be omitted from each drawing.

[0012] FIG. 1 is a schematic diagram of a rotating electric machine system 1 according to an embodiment. The rotating electric machine system 1 is used, for example, in, but not limited to, fans, pumps, compressors, and other general industrial machinery. The rotating electric machine system 1 includes a self-starting rotating electric machine 2 and a control device 4 that controls the rotating electric machine 2. The rotating electric machine 2 is shown in cross section perpendicular to its rotation axis R.

[0013] The rotating electric machine 2 includes a stator 10 and a rotor 12 that rotates about a rotation axis R relative to the stator 10.

[0014] Hereinafter, the direction parallel to the rotation axis R of the rotor 12 will be referred to as the axial direction, any direction passing through the rotation axis R on a plane perpendicular to the rotation axis R will be referred to as the radial direction, the side closer to the rotation axis R in the radial direction will be referred to as the inner side, and the side farther away will be referred to as the outer side, and the direction along the circumference of a circle centered on the rotation axis R on a plane perpendicular to the rotation axis R will be referred to as the circumferential direction.

[0015] The stator 10 includes a stator core 20, a first winding 22 which is a winding for starting, and a second winding 24 which is a winding for synchronous operation. The stator core 20 includes an annular portion 26 and a plurality of (here, 48) teeth 28 extending radially inward from the annular portion 26. The stator core 20 is formed, for example, by laminating a plurality of electromagnetic steel sheets.

[0016] A first winding 22 and a second winding 24 are arranged in slots 29 between circumferentially adjacent teeth 28 by distributed winding or concentrated winding. The first winding 22 is, but is not limited to, a three-phase winding, and is connected to generate a rotating magnetic field with P (P≧2) poles (for example, four poles). The second winding 24 is, but is not limited to, a three-phase winding, and is connected to generate a rotating magnetic field with 2P poles (for example, eight poles).

[0017] There is no particular restriction on the radial positional relationship between the first winding 22 and the second winding 24. Therefore, the first winding 22 may be disposed radially outward of the second winding 24 as in the illustrated example, or the first winding 22 may be disposed radially inward of the second winding 24 as in the illustrated example.

[0018] The rotor 12 includes a rotor core 30 and P (here, four) magnets 32. The rotor core 30 is a so-called solid iron core. In other words, the rotor core 30 is a solid body. In this specification, "solid body" refers to a seamless, single piece of material. Therefore, a solid body is a non-laminated body and also a non-jointed body. The rotor core 30 is formed of a magnetic material, for example, carbon steel such as S45C. The rotor core 30 includes an annular portion 34 and P protrusions 36 protruding radially outward from the annular portion 34. The P protrusions 36, i.e., multiple protrusions 36, are arranged at equal intervals around the circumference. A rotating shaft 6 is fitted into the center of the rotor core 30.

[0019] The magnet 32 is a permanent magnet. The magnet 32 is formed in the shape of a plate with an arc-shaped cross section. The magnet 32 is fixed to the outer peripheral surface of the rotor core 30 between the protrusions 36 (i.e., the outer peripheral surface 34a of the annular portion 34), for example, by adhesive. The magnet 32 faces the teeth 28 of the stator core 20 in the radial direction. Because the magnet 32 is fixed to the outer peripheral surface (i.e., the surface) of the rotor core 30, manufacturing is easier than if it were not fixed in this way.

[0020] Although not particularly limited, the protrusion 36 and the magnet 32 have arc-shaped outer peripheral surfaces with the same radius of curvature centered on the rotation axis R. In other words, the outer peripheral surfaces of the protrusion 36 and the magnet 32 are flush with each other.

[0021] The rotor core 30 has a higher magnetic permeability than air. The magnets 32, which are permanent magnets, generally have approximately the same magnetic permeability as air. Therefore, the rotor core 30 has P magnetic salient poles, which are portions through which magnetic flux tends to flow radially outward, and are formed by protrusions 36.

[0022] The P magnets 32 are magnetized so that their outer circumferential sides have the same polarity (here, north pole). The magnetic flux of the magnets 32 flows into the protrusions 36 via the annular portions 34 and passes through the protrusions 36 toward the radially outward direction. As a result, the protrusions 36 function as magnetic poles of the opposite polarity to the outer circumferential sides of the magnets 32 (here, south poles). In other words, the rotor 12 of this embodiment is a consequent pole type rotor in which the protrusions 36 function as magnetic poles of the opposite polarity to the outer circumferential sides of the magnets 32, and has a total of 2P magnetic poles: P magnetic poles due to the magnets 32 and P magnetic poles due to the protrusions 36.

[0023] One or more notches (grooves) 34b are formed in the outer peripheral surface (surface) 34a of the annular portion 34 of the rotor core 30, which faces the magnet 32 in the radial direction. The notches 34b preferably extend in the axial direction as shown. By providing the notches 34b, it is possible to prevent eddy currents from being generated in the outer peripheral surface 34a of the annular portion 34, and to prevent the magnet 32 from generating heat.

[0024] The control device 4 supplies a drive current to the rotating electric machine 2 to control the rotation of the rotor 12. Specifically, the control device 4 supplies a drive current to the first winding 22 and the second winding 24 of the stator 10. The control device 4 may typically include a drive circuit. The control device 4 may also include an inverter. In any case, the configuration of the control device 4 is not particularly limited.

[0025] The above is the basic configuration of the rotating electric machine system 1. Next, its operation will be described. When the rotor 12 is stopped, the control device 4 starts supplying a drive current to the first winding 22. When the drive current flows through the first winding 22, a P-pole rotating magnetic field is generated along the teeth 28. This P-pole rotating magnetic field causes an eddy current to flow in the outer circumferential surface 36a of the protrusion 36, generating an induced torque and starting the rotor 12.

[0026] When the rotational speed of rotor 12 reaches approximately half the rotational speed of the P-pole rotating magnetic field, control device 4 stops the supply of power to first winding 22 to stop the generation of the P-pole rotating magnetic field, while starting the supply of drive current to second winding 24. As the drive current flows through second winding 24, a 2P-pole rotating magnetic field is further generated along teeth 28. This 2P-pole rotating magnetic field applies torque to magnet 32 and protrusions 36, causing rotor 12 to rotate at a synchronous speed. The supply of drive current to first winding 22 may be stopped substantially simultaneously with the start of supply of drive current to second winding 24. Alternatively, the supply of drive current to first winding 22 may be stopped and the supply of drive current to second winding 24 may be started without delay. Alternatively, the supply of drive current to first winding 22 may be stopped and the supply of drive current to second winding 24 may be started without delay.

[0027] Next, the inventors performed a simulation under the following conditions to confirm that the rotating electrical machine system 1 according to this embodiment is capable of self-starting and stable synchronization. <Stator 10> Outer diameter of stator core 20: 160mm Inner diameter of stator core 20: 100mm Gap between the stator core 20 and the rotor core 30: 0.40 mm Stator core 20 stack length (axial length): 50.0 mm Number of slots 29 in stator core 20: 48 <Rotor 12> Rotor core 30 outer diameter: 99.2 mm Rotor core 30 inner diameter: 38.0 mm Circumferential length of the outer surface of magnet 32: 4.30 Rotor core 30 stack length (axial length): 50.0 mm

[0028] 2 is a diagram showing the results of a simulation of the starting characteristics of the rotating electrical machine 2. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the rotation speed of the rotor 12 of the rotating electrical machine 2.

[0029] It can be seen from FIG. 2 that when the rotor 12 is stopped and a rotating magnetic field of the P pole is generated by energizing the first winding 22, the rotor 12 starts to rotate.

[0030] In addition, the rotation speed of the rotor 12 is about half the rotation speed of the rotating magnetic field of the P pole (here, 900 min -1 ), when the P-pole rotating magnetic field generated by the first winding 22 is switched to a 2P-pole rotating magnetic field generated by the second winding 24, the rotation speed of the rotor 12 fluctuates slightly immediately thereafter, but it can be seen that it gradually converges towards the synchronous speed.

[0031] FIG. 3 is a diagram showing the results of a simulation of torque change with respect to the rotation speed of the rotating electrical machine 2. In FIG. 3, the horizontal axis represents the rotation speed of the rotor 12 of the rotating electrical machine 2, and the vertical axis represents the induced torque generated in the rotor 12. From FIG. 3, the induced torque increases as the rotation speed increases from 0 to 900 min -1 It can be seen that the induction torque is 20 Nm or more in the range of 1000 rpm, and that the induction torque is sufficient to accelerate the rotor 12.

[0032] According to the present embodiment described above, it is possible to realize a self-startable rotating electric machine 2 having a simple structure that does not have a squirrel cage like conventional rotating electric machines. This reduces the manufacturing cost of the rotating electric machine 2.

[0033] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. Modifications are shown below.

[0034] (Variation 1) Fig. 4 is a schematic diagram of a rotary electric machine system 1 according to a modified example. Fig. 4 corresponds to Fig. 1. The following mainly describes the differences from the embodiment.

[0035] In this modified example, the P protrusions 36 of the rotor core 30 are formed separately from the annular portion 34 and are joined to the annular portion 34. The joining method is not particularly limited, and may be mechanical joining, for example. In the illustrated example, the protrusions 36 are joined by slidingly fitting engagement protrusions 36b, which have a substantially T-shaped cross section and are provided on the inner periphery of the protrusions 36, into holes 34c, which are provided on the outer periphery of the annular portion 34. The holes 34c only need to have a shape corresponding to (i.e., a complementary shape with) the engagement protrusions 36b.

[0036] Fig. 5 is a cross-sectional view taken along line AA in Fig. 4. The annular portion 34 is a laminate. Although not particularly limited, the number of layers in the illustrated example is 24. The annular portion 34 is formed, for example, by laminating a plurality of electromagnetic steel sheets.

[0037] As shown in the figure, the protrusion 36 is a laminate or a block (which can also be considered as a laminate with one layer) having fewer layers than the annular portion 34. Although not particularly limited, in the example shown, the number of layers is three.

[0038] Grooves 36c extending in the circumferential direction may be provided on the outer peripheral surface 36a of the protrusion 36. This makes it possible to prevent overheating by limiting the current flowing through the outer peripheral surface 36a of the protrusion 36. Note that the grooves 36c are not limited to the example shown in the figure.

[0039] According to this modified example, compared to when the protrusion 36 is made into a laminate with the same number of layers as the annular portion 34, more eddy currents flow in the outer surface 36a of the protrusion 36, and therefore a higher induced torque is generated, allowing the rotor 12 to start.

[0040] Furthermore, if eddy currents flow to the inside of the magnet 32, the magnet 32 will heat up, and if the magnet 32 is fixed to the rotor core 30 with adhesive, for example, there is a risk that the magnet 32 will become detached. In contrast, in this modified example, the annular portion 34 is a laminated body, and therefore it is possible to prevent eddy currents from being generated on the outer circumferential surface 34a of the annular portion 34, and it is possible to prevent the magnet 32 from being heated.

[0041] (Variation 2) Fig. 6 is a schematic diagram of a rotating electrical machine system 1 according to another modification. Fig. 6 corresponds to Fig. 1. The following mainly describes the differences from the embodiment.

[0042] The rotor 12 includes a rotor core 30 and P (here, four) sets of magnets 32. The rotor core 30 is formed in an annular shape. P sets of magnet accommodating holes 30a are formed in the rotor core 30, each set being doubled in the radial direction and spaced apart in the circumferential direction.

[0043] The magnet 32 is formed in the shape of a plate that is long in the axial direction and has a rectangular cross section. The magnet 32 is housed in the magnet housing hole 30a of the rotor core 30 and fixed therein by, for example, an adhesive. The shape of the magnet 32 is not particularly limited, and the cross section may be formed in an arc shape.

[0044] Both end portions 30b of the magnet accommodating holes 30a extend toward the outer peripheral surface of the rotor core 30, and form flux barriers that suppress leakage magnetic flux between adjacent magnets 32.

[0045] To reiterate, rotor core 30 has a higher magnetic permeability than air, and magnets 32, which are permanent magnets, generally have approximately the same magnetic permeability as air. Therefore, magnetic flux flows more easily in circumferential region 30c (region surrounded by dotted line) on the outer periphery of rotor core 30 where magnet accommodating holes 30a are not formed than in circumferential region 30d (region surrounded by dashed line) where magnet accommodating holes 30a are formed, forming a magnetic salient pole. In other words, rotor 12 of this modified example also has P magnetic salient poles in the circumferential direction.

[0046] In this modified example, when a driving current flows through the first winding 22, a rotating magnetic field of a P pole is generated along the teeth 28, and eddy currents flow in the outer peripheral portion of the region 30d that constitutes the magnetic salient pole on the outer surface 30e of the rotor core 30, generating an induced torque, and the rotor 12 starts.

[0047] This modification can achieve the same effects as the embodiment. Furthermore, this modification can prevent the magnet 32 from peeling off from the rotor core 30 due to centrifugal force by embedding the magnet 32 in the rotor core 30. Furthermore, it can prevent eddy currents from being generated on the outer peripheral surface of the magnet 32, and can prevent the magnet 32 from generating heat.

[0048] In Figure 6, an example is described in which the magnet accommodating holes 30a and magnets 32 are arranged in two layers in the radial direction, but as a further variation, only one magnet accommodating hole 30a and magnet 32 may be provided in the radial direction, or three or more layers may be arranged.

[0049] (Variation 3) Fig. 7 is a cross-sectional view of the rotor 12 of a rotating electric machine 2 according to yet another modified example. Fig. 7 is a cross-sectional view of the rotor 12 cut along a plane including the rotation axis R. The stator 10 is not shown in Fig. 7. Figs. 8(a) and 8(b) are cross-sectional views of the rotating electric machine 2, respectively, and correspond to the cross-sectional view along line BB and line CC in Fig. 7.

[0050] The rotor 12 of this modified example includes a first rotor portion 112A and a second rotor portion 112B that are aligned in the axial direction.

[0051] The first rotor portion 112A includes a first rotor core 130A. The first rotor core 130A includes an annular portion 134A and P (e.g., four) protrusions 136A protruding radially outward from the annular portion 134A. The P protrusions 136A, i.e., the plurality of protrusions 136A, are provided at equal intervals in the circumferential direction. The first rotor core 130A is a block body, similar to the rotor core 30 of the embodiment. Alternatively, the first rotor core 130A is similar to the rotor core 30 of the first modification example, in that the annular portion 134A and the protrusions 136A are formed as separate bodies, the annular portion 134A is a laminated body, and the protrusions 136A are a laminated body having fewer layers than the annular portion.

[0052] The second rotor portion 112B includes a second rotor core 130B and 2P magnets 32. The second rotor core 130B is formed in an annular shape. The 2P magnets 32 are magnetized so that the magnetic poles on the outer periphery alternate in the circumferential direction. The 2P magnets 32 may be embedded in the second rotor core 130B. In either case, the second rotor portion 112B is configured not to have magnetic salient poles. The second rotor core 130B is formed, for example, by laminating a plurality of electromagnetic steel plates.

[0053] The stator 10 of this modified example includes a first stator portion 10A and a second stator portion 10B aligned in the axial direction. The first stator portion 10A includes a first stator core 20A and a first winding 22. The first stator core 20A includes a first annular portion 26A and a plurality of (here, 48) first teeth 28A extending radially inward from the first annular portion 26A. The first stator core 20A is formed, for example, by laminating a plurality of electromagnetic steel sheets. The first winding 22 is, although not limited to, a three-phase winding here, and is connected to generate a rotating magnetic field of the P pole.

[0054] The second stator portion 10B includes a second stator core 20B and a second winding 24. The second stator core 20B includes a second annular portion 26B and a plurality of (here, 48) second teeth 28B extending radially inward from the second annular portion 26B. The second stator core 20B is formed, for example, by laminating a plurality of electromagnetic steel sheets. The second winding 24 is a three-phase winding here, although not particularly limited thereto, and is connected to generate a rotating magnetic field with two poles P.

[0055] In this modification, when a driving current is supplied to the first winding 22 of the first stator portion 10A to generate a rotating magnetic field of the P pole while the rotor 12 is stopped, eddy currents flow on the outer peripheral surface of the protrusion 136A of the first stator core 20A of the first stator portion 10A, generating an induced torque and starting the first rotor portion 12A and the rotor 12. When the rotational speed of the rotor 12 has accelerated to about half the rotational speed of the rotating magnetic field of the P pole, a driving current is supplied to the second winding 24 to generate a rotating magnetic field of the 2P poles, and magnetic interaction between the rotating magnetic field of the 2P poles and the 2P magnetic poles of the second rotor portion 12B causes the second rotor portion 12B and the rotor 12 to rotate at a synchronous speed.

[0056] According to this modification, it is possible to achieve the same effects as those of the embodiment.

[0057] In this modification, the stator 10 and the rotor 12 are each divided into two parts in the axial direction, but they may also be divided into three or more parts in the axial direction. For example, the stator 10 and the rotor 12 may be divided into three parts in the axial direction, in which case the central rotor part in the axial direction may be configured similarly to the first rotor part 12A, and the rotor parts on both sides may be configured similarly to the second rotor part 12B. Of course, the central rotor part may be configured similarly to the second rotor part 12B, and the rotor parts on both sides may be configured similarly to the first rotor part 12A.

[0058] (Variation 4) Fig. 9 is a cross-sectional view of a rotating electric machine 202 according to yet another modification. Fig. 9 is a cross-sectional view of the rotating electric machine 202 cut along a plane including the rotation axis R. Fig. 10 is a view of the rotor 212 in Fig. 9 as viewed in the axial direction. The rotating electric machine 202 of this modification is a so-called axial gap type rotating electric machine. The rotating electric machine 202 includes two stators 210 and a rotor 212 provided between the two stators 210.

[0059] Stator 210 has windings (not shown) arranged thereon, which generate a rotating magnetic field of P poles and 2P poles. Note that it does not matter whether the windings are distributed windings or concentrated windings.

[0060] The rotor 212 includes an annular rotor core 230 and a plurality of magnets 232. The rotor core 230 corresponds to the rotor core 30 of the embodiment. Specifically, the rotor core 230 is a so-called solid iron core and is formed of a magnetic material, for example, carbon steel such as S45C. The rotor core 230 has a plurality of magnet accommodating holes 230a formed at equal intervals in the circumferential direction, penetrating the rotor core 230 in the axial direction. The magnets 232 are accommodated in the magnet accommodating holes 230a. The magnets 232 are magnetized in the axial direction, and all of them have the same magnetization direction. A circumferential region 230c (region surrounded by a dotted line) where no magnet accommodating holes 230a are formed allows magnetic flux to flow more easily than a circumferential region where the magnet accommodating holes 230a are formed, and constitutes a magnetic salient pole.

[0061] According to this modification, it is possible to achieve the same effects as those of the embodiment.

[0062] (Variation 5) In the embodiment and the first and second modifications, the stator 10 is described as having a first winding 22 and a second winding 24, i.e., a double winding. However, the present invention is not limited to this, and the stator 10 may have a single winding. In this case, the number of poles of the rotating magnetic field to be generated can be changed by switching the connections. A single winding results in a simpler structure.

[0063] (Variation 6) In the embodiment and the above-mentioned modified examples, a so-called inner rotor type rotating electric machine has been described, but this is not limited to this, and the technical ideas of the present embodiment and the above-mentioned modified examples may also be applied to a so-called outer rotor type rotating electric machine.

[0064] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the combined effects of the combined embodiments and modifications. [Explanation of symbols]

[0065] 1 rotating electric machine system, 10 stator, 12 rotor, 22 first winding, 24 second winding.

Claims

1. a stator; a rotor that rotates relative to the stator; Equipped with the stator includes a winding for generating a rotating magnetic field of a P pole (P is a natural number of 2 or more) and two P poles; the rotor includes a rotor core having an annular portion and P salient poles extending from the annular portion and arranged in a circumferential direction, and has 2P magnetic poles arranged in a circumferential direction, the annular portion is a laminate, The rotary electric machine wherein the salient pole is a block salient pole or a laminated body having a smaller number of laminations than the annular portion.

2. 2. The rotating electric machine according to claim 1, wherein the rotor is a consequent pole type rotor having P magnetic poles formed by magnets and P magnetic poles formed by the rotor core.

3. the magnet is disposed on a surface of the rotor core, The rotating electric machine according to claim 2 , wherein a notch is formed in a surface portion of the rotor core facing the magnet.

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