Synchronous induction motor

Abstract

To provide a synchronous induction motor capable of sufficiently utilizing magnetic flux.SOLUTION: The synchronous induction motor 1 according to the embodiment includes a stator 3 provided with coils 2, a first rotor 5 provided with permanent magnets 4, and a second rotor 8 provided with conductor bars 6 and short-circuit rings 7, and the first rotor 5 and the second rotor 8 are concentrically arranged with the stator 3 interposed therebetween and rotate in synchronization with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a synchronous induction motor. [Background technology]

[0002] Conventionally, as described in Patent Document 1, for example, there is a synchronous induction motor that has a secondary conductor and a permanent magnet in the rotor, operates as an induction motor at start-up, and operates as a synchronous motor after acceleration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-119727 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional induction synchronous motors, the secondary conductors are positioned closer to the outer periphery of the rotor, and therefore the permanent magnets are positioned closer to the inner periphery than the secondary conductors. This increases the distance between the permanent magnets and the stator, which can lead to the risk of not being able to fully utilize the magnetic flux after acceleration.

[0005] Therefore, a synchronous induction motor capable of fully utilizing magnetic flux is provided. [Means for solving the problem]

[0006] The induction synchronous motor according to the embodiment comprises a stator provided with a coil, a first rotor provided with a permanent magnet, and a second rotor provided with a conductor bar and a short-circuit ring, the first rotor and the second rotor being arranged concentrically on either side of the stator and rotating synchronously with each other. [Brief explanation of the drawings]

[0007] [Figure 1]FIG. 1 is a diagram illustrating a configuration example of a synchronous induction motor according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating a configuration example in which a first rotor and a second rotor are coupled together; [Figure 3] Diagram 1 showing another example of the configuration of an induction synchronous motor [Figure 4] Diagram 2 showing another example of the structure of an induction synchronous motor [Figure 5] Diagram 3 showing another example of the configuration of an induction synchronous motor [Figure 6] Schematic diagram showing another example of permanent magnet arrangement [Figure 7] FIG. 10 is a diagram schematically illustrating another example of the configuration of the stator. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, the embodiments will be described with reference to the drawings. Although several configuration examples with different details will be described below, the basic concept will first be described with reference to Figs. 1 to 3.

[0009] As shown in Fig. 1, the synchronous induction motor 1 of this embodiment includes a stator 3 provided with a coil 2, a first rotor 5 provided with a permanent magnet 4, and a second rotor 8 provided with a conductor bar 6 and a short-circuit ring 7 (see Fig. 2). The stator 3, first rotor 5, and second rotor 8 are housed in a frame (not shown). Fig. 1 is a cross-sectional view taken along line II in Fig. 2, and shows an area of ​​approximately 1 / 6 of the circumference of the synchronous induction motor 1 as viewed from the axial direction, but hatching of the stator 3, first rotor 5, and second rotor 8 has been omitted to make the drawing easier to understand.

[0010] The stator 3 is formed into a generally cylindrical shape by laminating a plurality of iron core materials, and has a plurality of mounting slots 9 arranged in the circumferential direction for mounting the coils 2. In this embodiment, the mounting slots 9 open on the outer periphery side, that is, on the side of the first rotor 5. Note that the number and shape of the mounting slots 9 are merely examples and are not limited to those shown in FIG. 1.

[0011] The first rotor 5 is formed into a generally cylindrical shape by laminating multiple iron core materials, and is arranged concentrically around the central axis of rotation (J) on the outer periphery of the stator 3. This first rotor 5 is formed with, for example, two magnet housing sections 10 lined up in the circumferential direction and open to the inner periphery, and a permanent magnet 4 is, for example, adhered to each magnet housing section 10. In other words, the permanent magnet 4 is provided on the first rotor 5 with a portion thereof exposed on the stator 3 side. Note that the number, shape, and arrangement of the permanent magnets 4 and magnet housing sections 10 are merely examples and are not limited to those shown in FIG. 1.

[0012] The second rotor 8 is formed into a generally cylindrical shape by laminating multiple iron core materials, and is arranged concentrically around the central axis of rotation (J) on the inner periphery of the stator 3. In other words, the second rotor 8 is arranged concentrically with the first rotor 5, with the stator 3 in between. Furthermore, on the outer periphery of the second rotor 8, that is, at a position closer to the stator 3, multiple conductor slots 11 are formed along the circumferential direction.

[0013] This second rotor 8 is formed by die-casting a conductor such as aluminum, so that conductor bars 6 are formed in conductor slots 11, and short-circuit rings 7 that short-circuit each conductor bar 6 are formed at both axial ends. Furthermore, the second rotor 8 has a shaft hole 13 formed in its center, through which a shaft member 12 passes, and the shaft member 12 is fixed into the shaft hole 13 by press-fitting or shrink-fitting. Note that the number and shape of the conductor slots 11 are merely examples and are not limited to those shown in FIG. 1.

[0014] When starting, the second rotor 8 of the induction motor 1 configured as above functions like an induction motor, generating starting torque, making it self-starting and allowing it to start from a commercial power source. After accelerating to near synchronous speed, the first rotor 5 acts as a field and the induction motor 1 is driven like a synchronous motor.

[0015] At this time, in the induction synchronous motor 1, the first rotor 5 and the second rotor 8 rotate in synchronization with each other. Specifically, as shown in Fig. 2 as a first example of connection, a connecting member 14 is fixed to one axial end face of each of the first rotor 5 and the second rotor 8. This connecting member 14 is formed in a shape that straddles the short-circuit ring 7 and the coil end 15, and as one rotor rotates, the other rotor rotates.

[0016] That is, in the case of connection example 1, the rotors are directly connected by the connecting member 14, so that they rotate in a synchronized state, i.e., as a unit and at the same rotation speed. However, as shown in connection example 2, by providing a connecting member 14A that connects the second rotor 8 and the shaft member 12, the first rotor 5 and the second rotor 8 can also be indirectly connected and synchronized. Furthermore, the connecting member 14 or the connecting member 14A can also be applied to other configuration examples described later. The stator 3 is fixed to the frame at the end opposite to the connecting member 14.

[0017] Next, the operation and effects of the above-described configuration will be described. As mentioned above, in conventional configurations, secondary conductors such as conductor bars 6 are positioned closer to the outer periphery to ensure starting torque, and permanent magnets 4 are positioned further inward than the secondary conductors, which can lead to concerns that the magnetic flux may not be fully utilized after acceleration. In this case, if the permanent magnets 4 are positioned further outward than the secondary conductors to enable effective use of the magnetic flux, sufficient starting torque may not be obtained. Furthermore, if the secondary conductors and permanent magnets 4 are positioned at roughly the same radial position, the amount of secondary conductors and permanent magnets 4 that can be positioned is reduced, which can result in deterioration of characteristics.

[0018] Therefore, in this embodiment, a stator 3 having a coil 2, a first rotor 5 having a permanent magnet 4, and a second rotor 8 having a conductor bar 6 and a short-circuit ring 7 are provided, and the first rotor 5 and the second rotor 8 are arranged concentrically on either side of the stator 3 and rotate synchronously with each other.

[0019] With this configuration, the induction synchronous motor 1 has the conductor bars 6 arranged closer to the outer periphery of the second rotor 8, thereby shortening the distance to the rotor and ensuring starting torque. Also, the induction synchronous motor 1 has the permanent magnets 4 arranged on the inner periphery of the first rotor 5, thereby shortening the distance between the permanent magnets 4 and the stator 3, allowing for more effective use of magnetic flux and improving efficiency. In other words, the induction synchronous motor 1 is configured to make full use of magnetic flux.

[0020] Furthermore, in the induction synchronous motor 1, the first rotor 5 is arranged on the outer periphery of the stator 3, the second rotor 8 is arranged on the inner periphery of the stator 3, and the openings of the mounting slots 9 are formed on the first rotor 5 side. As a result, after starting, magnetic flux flows only between the first rotor 5 and the stator 3, shortening the magnetic path and enabling a high power factor, thereby improving the operating characteristics during normal operation.

[0021] Furthermore, in the induction synchronous motor 1, the permanent magnets 4 are arranged in a state where at least a portion of each is exposed, thereby improving the utilization efficiency of the magnetic flux.

[0022] <Another example of a synchronous induction motor configuration, part 1> Although the induction synchronous motor 1 is capable of self-starting as described above, there is a risk that it may not start if the starting torque is insufficient. Furthermore, in actual applications where the induction synchronous motor 1 is used, it is anticipated that reliable starting may be important. In such cases, in order to ensure reliable starting, in other words, to improve the starting characteristics, it is considered necessary to make effective use of the magnetic flux on the second rotor 8 side.

[0023] Therefore, in the synchronous induction motor 1A shown in Figure 3, the mounting slots 9 of the stator 3A are formed in a shape that opens on the inner periphery side, that is, on the side of the second rotor 8A. This results in a relatively larger starting torque compared to the configuration in Figure 1, improving starting characteristics and ensuring reliable starting. Note that the induction motor shown in Figure 1 and the synchronous induction motor 1A shown in Figure 3 are not superior to each other, but rather the configuration can be selected appropriately depending on whether starting characteristics or operating characteristics are prioritized. Note that the first rotor 5A is the same as the first rotor 5 shown in Figure 1.

[0024] The stator 3A and second rotor 8A shown in FIG. 3 share the same general configuration as induction motors. Therefore, the stator 3A and second rotor 8A can be reused from other existing induction motors or can be adapted for use in other induction motors. This allows the induction synchronous motor 1A to be manufactured using an existing induction motor manufacturing line, and parts can be shared with other induction motors, greatly contributing to a reduction in manufacturing costs. Of course, it is also possible to manufacture only the stator 3A or only the second rotor 8A on an existing induction motor manufacturing line, or to share parts with existing induction motors.

[0025] <Another example of a synchronous induction motor configuration, part 2> The synchronous induction motor 1 is configured to effectively utilize magnetic flux by shortening the distance between the stator 3 and the conductor bars 6 or permanent magnets 4. In this case, as in the synchronous induction motor 1B shown in FIG. 4, a first rotor 5B provided with permanent magnets 4 can be arranged on the inner periphery of the stator 3B, and a second rotor 8B provided with conductor bars 6 and a short-circuit ring 7 can be arranged on the inner periphery of the stator 3B, forming a concentric arrangement. Note that the stator 3B is the same as the stator 3A shown in FIG. 3.

[0026] Even with this configuration, it is possible to arrange the permanent magnets 4 and conductor bars 6 close to the stator 3B, and to obtain the various effects described above, such as making effective use of magnetic flux. Furthermore, by forming the mounting slots 9 so that they open toward the first rotor 5, the magnetic path is shortened, achieving a high power factor and improving operating characteristics during normal operation.

[0027] The stator 3B and the second rotor 8B shown in FIG. 4 share a common configuration with a typical synchronous motor. Therefore, the stator 3B and the second rotor 8B can be reused from other existing synchronous motors or can be adapted for use in other synchronous motors. This allows the stator 3B and the second rotor 8B to be manufactured using an existing synchronous motor manufacturing line or to share parts with synchronous motors, which significantly contributes to reducing manufacturing costs. Of course, it is also possible to manufacture only the stator 3B or only the second rotor 8B using an existing synchronous motor manufacturing line or to share parts with other synchronous motors.

[0028] <Another example of a synchronous induction motor configuration, part 3> In the second alternative configuration example, emphasis is placed on operational characteristics after acceleration, but if emphasis is placed on starting characteristics at startup, as in the case of a synchronous induction motor 1C shown in Fig. 5, the mounting slots 9 of the stator 3C can be formed so that they open on the second rotor 8C side, that is, on the outer periphery. This configuration also achieves the various effects described above, such as the effective use of magnetic flux, and improves starting characteristics by increasing the starting torque. Note that the first rotor 5C is the same as the first rotor 5B shown in Fig. 4.

[0029] <Other examples of permanent magnet arrangement> Up to this point, we have shown configuration examples in which the permanent magnets 4 are arranged in an exposed state at least in part, but as in the synchronous induction motor 1D shown as another arrangement example 1 in FIG. 6, for example, the permanent magnets 4 can be inserted into magnet insertion holes 16 formed inside the first rotor 5D and embedded in the first rotor 5D. In this case, it is also possible to have a configuration in which multiple permanent magnets 4 are embedded. The stator 3D and second rotor 8D can be appropriately selected from those shown in FIGS. 1 to 5.

[0030] Even with this configuration, the various effects described above can be obtained, such as the effective use of magnetic flux. The number of permanent magnets 4 needs to be one or more, and it is also possible to arrange three or more permanent magnets 4 radially, as in a two-layer structure. Furthermore, depending on whether starting characteristics or running characteristics are prioritized, the mounting slots 9 of the stator 3D can be opened on either the outer circumferential side or the inner circumferential side, allowing for a configuration that suits the respective characteristics.

[0031] Furthermore, as shown in the second example of the arrangement of the induction synchronous motor 1E, the permanent magnets 4 may be arranged to cover the inner circumferential surface of the first rotor 5E, i.e., the permanent magnets 4 may be arranged in their entirety so as to be exposed from the first rotor 5E. In this case, although not shown, multiple permanent magnets 4 are provided adjacent to each other in the circumferential direction, and are arranged so that the magnetic poles of adjacent permanent magnets 4 face in opposite directions. This arrangement also achieves the various effects described above, such as the effective use of magnetic flux. The stator 3E and second rotor 8E may be selected from those shown in FIGS. 1 to 5 as appropriate.

[0032] Furthermore, as in the third example of the induction synchronous motor 1F, when the first rotor 5F is arranged on the inner periphery of the stator 3F, the permanent magnets 4 can be embedded inside the first rotor 5F. This configuration also achieves the various advantages described above, such as effective utilization of magnetic flux. The number of permanent magnets 4 can be one or more; three or more can be arranged, or multiple permanent magnets 4 can be arranged radially, as in a two-layer structure. Depending on whether starting characteristics or operating characteristics are prioritized, the mounting slots 9 of the stator 3D can be opened on either the outer or inner periphery, allowing for a configuration suited to the respective characteristics. The stator 3F and second rotor 8F can be appropriately selected from those shown in Figures 1 to 5.

[0033] Furthermore, as in the induction synchronous motor 1G shown as alternative arrangement example 4, a configuration can be adopted in which the permanent magnets 4 are arranged to cover the outer peripheral surface of the first rotor 5G. In this case, although not shown, a plurality of permanent magnets 4 are provided adjacent to each other in the circumferential direction, and are arranged so that the magnetic poles of adjacent permanent magnets 4 face in opposite directions. Even with this configuration, the various effects described above can be obtained, such as the effective use of magnetic flux. The stator 3G and second rotor 8G can be appropriately selected from those shown in Figures 1 to 5.

[0034] Furthermore, although the symbols D, E, F, G, etc. are omitted, if the stator 3 or the second rotor 8 in the above-mentioned Arrangement Example 1 and Arrangement Example 2 has a configuration common to an existing induction motor, the stator 3 or the second rotor 8 can be reused from the existing induction motor or can be diverted to another induction motor. Furthermore, if the stator 3 or the first rotor 5 in the above-mentioned Arrangement Example 3 and Arrangement Example 4 has a configuration common to an existing synchronous motor, the stator 3 or the first rotor 5 can be reused from the existing induction motor or can be diverted to another synchronous motor.

[0035] <Other examples of stator configurations> Up to this point, we have been using a stator 3 with laminated iron core material as an example. However, the stator 3H can also have a so-called coreless structure, as in the synchronous induction motor 1H shown in Figure 7. In this case, the stator 3H does not have an iron core material, and each coil 2 is fixed in a predetermined positional relationship using resin material 17. This configuration also allows the coils 2 to be closer to the permanent magnets 4 and conductor bars 6, thereby achieving the various advantages described above, such as effective use of magnetic flux. Furthermore, since there is no iron core material, there are no slot openings, making it possible to effectively utilize magnetic flux from both the first rotor 5H and the second rotor 8H. Note that the first rotor 5H and the second rotor 8H can be appropriately selected from those shown in Figures 1 to 6 and the like.

[0036] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0037] In the drawings, 1 and 1A to 1H indicate an induction synchronous motor, 2 indicates a coil, 3 and 3A to 3H indicate a stator, 4 indicates a permanent magnet, 5 and 5A to 5H indicate a first rotor, 6 indicates a conductor bar, 7 indicates a short-circuit ring, 8 and 8A to 8H indicate a second rotor, and 17 indicates a resin material.

Claims

1. a stator provided with a coil; a first rotor provided with a permanent magnet; a second rotor provided with conductor bars and a short-circuit ring; The first rotor and the second rotor are arranged concentrically with the stator in between, and rotate in synchronization with each other in a synchronous induction motor.

2. the first rotor is disposed on the outer circumferential side of the stator, 2. The synchronous induction motor according to claim 1, wherein the second rotor is disposed on the inner circumferential side of the stator.

3. the first rotor is disposed on the inner circumferential side of the stator, 2. The synchronous induction motor according to claim 1, wherein the second rotor is disposed on the outer circumferential side of the stator.

4. 2. The synchronous induction motor according to claim 1, wherein the permanent magnet is provided on the first rotor with at least a portion of the permanent magnet exposed to the rotor side.

5. 3. The synchronous induction motor according to claim 2, wherein the stator and the second rotor are adapted from another existing induction motor or can be adapted for use in another induction motor.

6. 4. The synchronous induction motor according to claim 3, wherein the stator and the first rotor are adapted from another existing synchronous motor or can be converted to another synchronous motor.

7. 5. The synchronous induction motor according to claim 1, wherein the stator has slots for mounting the coils, the slots opening toward the first rotor.

8. 5. The synchronous induction motor according to claim 1, wherein the stator has slots for mounting the coils, the slots opening toward the second rotor.

9. 5. The synchronous induction motor according to claim 1, wherein the stator has a coreless structure in which the coils are hardened with a resin material.

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