Rotary electric machine

Abstract

To provide a rotary electric machine capable of realizing a high output without upsizing a device.SOLUTION: A rotary electric machine comprises a rotor 11 and a stator 12. The rotor rotatably provided with a rotation axis C as a center comprises a plurality of rotor cores 111n to which a plurality of permanent magnets Mn are arranged, respectively. The stator provided in a circumferential direction of the rotor comprises a plurality of stator cores 121n to which a plurality of windings are arranged, respectively. Rotor cores each to which respective permanent magnets are arranged form a plurality of rotor poles, and stator cores each to which respective windings are arranged form a plurality of stator poles. A ratio of the number of stator poles Psn to the number of rotor poles Prn is represented by Psn:Prn=2:1.SELECTED DRAWING: Figure 2A

Description

[Technical field]

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

[0002] Technology related to rotating electric motors has been attracting attention as one of the technological themes of green innovation. Currently, there are several types of rotating electric motors with different characteristics for generating torque. For example, there is a synchronous motor equipped with a permanent magnet on the outer circumferential surface of the rotor core (see Patent Document 1). As a result, the range of application of rotating electric motors in society is expanding, and they are being used in various industrial fields. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 5982776 Summary of the Invention [Problem to be solved by the invention]

[0004] In rotating electric machines, it is desirable to increase the torque (achieve high output). Methods for increasing the torque include, for example, increasing the number of poles in the stator (multi-polarization method). However, with the methods used so far, there is a possibility that the rotating electric machine will become larger, and even if the torque can be increased, the range of application of the rotating electric machine will be narrowed, leaving room for improvement. Considering that rotating electric machines will be used in various aspects of society, it is desirable to be able to increase the torque without increasing the size of the rotating electric machine.

[0005] An object of the present invention is to provide a rotating electric machine capable of achieving high output without increasing the size of the device. [Means for solving the problem]

[0006] The present invention employs the following technical means to solve the above problems. The claims and the symbols in parentheses described in this section are examples showing the corresponding relationship with the specific means described in the embodiment described later as one aspect. Therefore, they do not limit the technical scope of the present invention.

[0007] A rotating electric machine (10) according to one aspect of the present invention includes a rotor (11) and a stator (12). The rotor (11) is rotatably provided around a rotation axis (C) and includes a plurality of rotor cores (111n) in which a plurality of permanent magnets (Mn) are arranged. The stator (12) is provided in the circumferential direction of the rotor and includes a plurality of stator cores (121n) in which a plurality of windings (Wn) are arranged. Each rotor core in which the permanent magnets are arranged forms a plurality of poles of the rotor, and each stator core in which the windings are arranged forms a plurality of poles of the stator. The rotating electric machine is configured such that the ratio of the number of poles of the stator (Psn) to the number of poles of the rotor (Prn) is Psn:Prn=2:1. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a rotating electric machine that can achieve high output without increasing the size. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of a rotating electric machine according to a first embodiment. [Figure 2A] FIG. 2A is a cross-sectional view taken along line AA showing a schematic configuration of a rotor and a stator according to the first embodiment. [Figure 2B] FIG. 2B is a BB cross-sectional view showing a schematic configuration of the rotor and the stator according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing the shape of a winding portion of the first pole-forming portion of the stator according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing the shape of the first pole forming portion of the stator according to the first embodiment. [Figure 5A]FIG. 5A is a diagram (part 1) showing a magnetic path generated between a rotor and a stator according to the first embodiment. [Figure 5B] FIG. 5B is a diagram (part 2) showing a magnetic path generated between the rotor and the stator according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing the relationship between torque and current phase angle (torque curve) in a typical interior permanent magnet synchronous motor (IPMSM). [Figure 7] FIG. 7 is a diagram showing the relationship between the torque and the phase angle of the current (torque curve) in the rotating electric machine according to the first embodiment. [Figure 8] FIG. 8 is a diagram showing a control system (drive circuit) for the rotating electric machine according to the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of control of the rotating electric machine according to the first embodiment. [Figure 10] FIG. 10 is a schematic configuration diagram of a rotating electric machine according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0011] First Embodiment FIG. 1 is a schematic diagram of a rotating electric machine 10 according to this embodiment. The rotating electric machine 10 according to this embodiment is a synchronous motor, which is an alternating-current motor whose rotational speed is equal to a synchronous speed. In other words, a synchronous motor is an electric motor that rotates at a synchronous speed determined by the frequency of a power source. As shown in FIG. 1, the rotating electric machine 10 is mainly composed of a rotor 11, a stator 12, an output shaft 13, and a housing case 14. The rotor 11 has a plurality of permanent magnets Mn. Thus, the rotating electric machine 10 according to this embodiment is an interior permanent magnet synchronous motor (IPMSM). Each permanent magnet Mn is arranged at a predetermined interval on the rotor 11. The rotor 11 is fixed to the output shaft 13. The rotor 11 outputs a rotational force generated by the rotational drive to a load to be driven via the output shaft 13. The stator 12 is provided in the circumferential direction of the rotor 11 in order to apply a force that rotates the rotor 11. The stator 12 has a plurality of armature windings Wn (hereinafter, referred to as "windings Wn" for convenience). The plurality of windings Wn are arranged at a predetermined interval on the stator 12. The stator 12 is fixed to a housing case 14 via a bracket (not shown). The output shaft 13 is supported by a bearing (not shown). The bearing is supported by the housing case 14. According to this configuration, in the rotating electric machine 10 according to this embodiment, when a multi-phase current is passed through each winding Wn of the stator 12 (when excited), a rotating magnetic field is generated that rotates at a rotational speed (i.e., a synchronous speed) determined by the frequency of the multi-phase current. As a result, the rotor 11 is attracted by the generated rotating magnetic field and rotates. 1, the direction of the rotation axis C of the rotor 11 is indicated by reference character Y, the vertical direction relative to the rotation axis C is indicated by reference character Z, and the horizontal direction relative to the rotation axis C is indicated by reference character X. These three-dimensional directions will be used in the same sense in the following description.

[0012] The present invention proposes a structure and a control method that realize a high volume ratio compared to conventional rotating electric machines. In the present invention, a high volume ratio means that a higher output is achieved than a conventional rotating electric machine (comparison object) even if the size is the same as the comparison object. In other words, it means that a high output can be achieved without making the rotating electric machine larger. It also means that the rotating electric machine can be made smaller if the output is the same. Since the output cost of a rotating electric machine is proportional to the volume, achieving a high volume ratio leads to a reduction in the output cost of the rotating electric machine. The inventors have conducted extensive research in consideration of these points. As a result, the inventors devised the following methods to achieve the above points: (i) a configuration in which the torque point at which maximum torque is generated (hereinafter, for convenience, referred to as the "maximum torque point") is increased compared to conventional configurations without increasing the number of magnetic poles of stator 12; (ii) a configuration in which the area of ​​the pole-facing surface of stator 12 (the pole-facing surface facing rotor 11) that generates torque is larger than conventional configurations; (iii) a configuration that utilizes a three-dimensional magnetic path (particularly transverse flux) that is generated when excited; and (iv) control using two-phase AC based on the configurations.

[0013] Generally, the ratio of the number of poles Psn of the stator 12 to the number of poles Prn of the rotor 11 is 3:1. In contrast, the present invention adopts a configuration in which the ratio of the number of poles Psn of the stator 12 to the number of poles Prn of the rotor 11 is 2:1, and the maximum torque point is doubled compared to the conventional configuration without increasing the number of poles Psn of the stator 12. In addition, the present invention adopts a configuration in which the rotor 11 has two pole-opposing surfaces of the stator 12 that generate torque, and the area of ​​the pole-opposing surfaces is doubled compared to the conventional configuration. Furthermore, the present invention adopts a configuration in which a three-dimensional magnetic path using a transverse magnetic flux is generated between the stator 12 and the rotor 11 when each winding Wn of the stator 12 is excited, and it is possible to use both the magnet torque Te and the reluctance torque Tr. With this configuration, the present invention realizes a higher volume ratio than the conventional one, and provides a rotating electric machine with high output with the same size (a rotating electric machine with the same output but small size).

[0014] (stator and rotor) 2A and 2B show cross-sectional views of a direction Z perpendicular to the axis of rotation C (axis of rotation C of rotor 11) of the rotating electric machine 10 according to this embodiment. FIG. 2A is a cross-sectional view taken along line AA showing a schematic configuration of the rotor 11 and the stator 12 according to this embodiment. FIG. 2B is a cross-sectional view taken along line BB showing a schematic configuration of the rotor 11 and the stator 12 according to this embodiment. In FIG. 2, the circumferential direction of the rotating electric machine 10 is indicated by reference character A, and the radial direction of the electric machine is indicated by reference character B. These two-dimensional directions are used in the same sense in the following explanations.

[0015] 2A and 2B, in order to clearly show the unique pole number ratio (Psn:Prn=2:1) ​​of the configuration of the present invention, an example is shown in which the number of poles of the rotor 11 is Prn:12 and the number of poles of the stator 12 is Psn:24. As shown in FIGS. 2A and 2B, the stator 12 has a plurality (24 pieces) of stator cores 121n (1211-1211) each having a predetermined space WS (hereinafter, for convenience, referred to as "coil space") for arranging each winding Wn. 24). Thus, each stator core 121n corresponds to a first pole forming portion. Each stator core 121n is arranged (annularly formed) at a predetermined interval (at a predetermined position) in the circumferential direction A of the stator 12. When the number of poles is 24, each stator core 121n (pole of the stator 12) is arranged within a range of a central angle of 15° (=360° / 24) based on the rotation axis C. If the interval between two adjacent stator cores 121n in the circumferential direction A is a central angle of 5°, the width of each stator core 121n in the circumferential direction A (pole width of the stator 12) corresponds to a central angle of 10° (=15°-5°). In addition, between the stator 12 and the rotor 11 in the radial direction B, a gap is provided that allows the rotor 11 to rotate with the stator 12 provided around it. Each stator core 121n is formed to extend from the inside (rotor 11 side) to the outside based on the rotation axis C. Therefore, a first end in the radial direction B of each stator core 121n is located outside the rotating electric machine 10, and a second end in the radial direction B is located on the pole-opposing surface 12S facing the rotor 11.

[0016] As described above, each stator core 121n has a winding Wn arranged in the coil space WS, and is excited by current flowing through the winding Wn. As a result, each stator core 121n forms a predetermined magnetic field. Furthermore, AC current of each phase of the two-phase AC flows through the winding Wn of each stator core 121n. The windings Wn are alternately (every other winding) connected in reverse such that the direction of the magnetic field alternates (is staggered) in the circumferential direction A when excited. If each phase of the two-phase AC (two phases that are shifted in phase by 180°) is defined as phase I and phase II, FIG. 2A shows each stator core 121n through which phase I AC current flows and each stator core 121n through which phase II AC current flows. n+1 1 shows an example of a stator 12 in which the first and second poles are alternately assigned.

[0017] As shown in FIG. 2B, the stator 12 has a first annular structural part 12a and a second annular structural part 12b. The annular structural parts 12a and 12b referred to here are, for example, planar and annular steel plates having a predetermined thickness. Each stator core 121n is integrally formed by connecting a first core part 121a of the first annular structural part 12a and a second core part 121b of the second annular structural part 12b in the rotation axis direction Y via a connecting part 121c. The space between the first core part 121a and the second core part 121b corresponds to a coil space WS in which the winding Wn is arranged. In other words, the conductor of the winding Wn is wound around the connecting part 121c. As a result, the winding Wn is located approximately at the center of the stator core 121n in the rotation axis direction Y. The first core portion 121a of the first annular structural portion 12a is fixed to the side plate 123a via a protruding portion 122a having a predetermined thickness provided in the rotation axis direction Y. The second core portion 121b of the second annular structural portion 12b is fixed to the side plate 123b via a protruding portion 122b having a predetermined thickness. In this manner, the stator 12 is configured by integrally forming a first pair of annular structural portions (twin rings). According to this configuration, each stator core 121n has a first pair of pole facing surfaces (two surfaces) as a pole facing surface 12S with respect to the rotor 11, the first pole facing surface 12Sa being a surface of the first core portion 121a facing the rotor 11, and the second pole facing surface 12Sb being a surface of the second core portion 121b facing the rotor 11. In this manner, in the rotating electric machine 10 according to this embodiment, the area of ​​the pole facing surface 12S of the stator 12 that generates torque is configured to be larger (twice as large) than in the conventional configuration.

[0018] As shown in FIG. 2A, the rotor 11 has an iron core made of a steel plate (e.g., a silicon steel plate), and includes a plurality (12 pieces) of rotor cores 111n (1111-1111), each of which has a predetermined space (not shown; hereinafter, for convenience, referred to as a "magnet space") for installing each permanent magnet Mn in the iron core. 12). Thus, each rotor core 111n corresponds to a second pole forming portion. Each rotor core 111n is arranged (annularly formed) at a predetermined interval (at a predetermined position) in the circumferential direction A of the rotor 11. Each rotor 111n is provided, for example, in the rotor main body 11mb. When the number of poles is 12, each rotor core 111n (pole of the rotor 11) is arranged within a range of a central angle of 30° (=360° / 12) based on the rotation axis C. If the interval between two adjacent rotor cores 111n in the circumferential direction A is a central angle of 10° (=5°×(2 / 1)), the width of each rotor core 111n in the circumferential direction A corresponds to a central angle of 20° (=30°−10°). In other words, the width of each permanent magnet Mn in the circumferential direction A (pole width of the rotor 11) corresponds to a central angle of 20° (=30°−10°). Each rotor core 111n is formed to extend from the outside (the stator 12 side) toward the inside with respect to the rotation axis C. Therefore, a first end in the radial direction B of each rotor core 111n is located inside the rotating electric machine 10, and a second end in the radial direction B is located on a pole-facing surface 11S facing the stator 12.

[0019] As described above, in each rotor core 111n, a permanent magnet Mn is installed in the magnet space to generate a predetermined magnetic field. Also, each permanent magnet Mn is arranged such that the S pole and the N pole are alternately (every other pole) positioned on the pole facing surface 11S side facing the stator 12 so that the direction of the magnetic field alternates in the circumferential direction A. Fig. 2A shows each rotor core 111n with its S pole positioned on the pole facing surface 11S side facing the stator 12, and each rotor core 111n with its N pole positioned on the pole facing surface 11S side facing the stator 12. n+1 1 shows an example of a rotor 11 in which the first and second poles are alternately assigned.

[0020] As shown in FIG. 2B, the rotor 11 has a third annular structural portion 11a and a fourth annular structural portion 11b. The annular structural portions 11a and 11b are, for example, planar and annular steel plates having a predetermined thickness. Each rotor core 111n is integrally formed with the rotor body 11mb by connecting the third core portion 111a of the third annular structural portion 11a and the fourth core portion 111b of the fourth annular structural portion 11b in the rotation axis direction Y via a connecting portion 111c. Each of the third core portion 111a and the fourth core portion 111b has a magnet space in which a permanent magnet Mn is installed. In other words, two permanent magnets Mn, a first permanent magnet Ma and a second permanent magnet Mb, are installed in one rotor core 111n. In this way, the rotor 11 is configured by integrally forming a pair of second annular structural portions (twin rings). According to this configuration, each rotor core 111n has a second pair of pole facing surfaces (two surfaces) as pole facing surfaces 11S facing the stator 12, which are a third pole facing surface 11Sa which is the surface facing the stator 12 of the third core portion 111a, and a fourth pole facing surface 11Sb which is the surface facing the stator 12 of the fourth core portion 111b.

[0021] In this way, the rotating electric machine 10 according to the present embodiment has a configuration in which the number of stator cores 112n is twice the number of rotor cores 111n, and the ratio of the number of poles Psn of the stator 12 to the number of poles Prn of the rotor 11 is 2:1. With this configuration, the maximum torque point is greater than that of the conventional configuration without increasing the number of poles Psn of the stator 12. In other words, in the configuration of the present invention, the number of poles Prn of the rotor 11 is increased without increasing the number of poles Psn of the stator 12, and the maximum torque point is greater than that of the conventional configuration. For example, when the number of poles Psn of the stator 12 is 24, the number of poles Prn of the rotor 11 is 12 in the configuration of the present invention, whereas the number of poles Prn of the rotor 11 is 8 in the conventional configuration in which the ratio of the number of poles Psn of the stator 12 to the number of poles Prn of the rotor 11 is 3:1. In other words, the maximum torque point of the configuration of the present invention is increased by 1.5 times (=12 / 8) compared to the conventional configuration.

[0022] Also, for example, in the case where there are 24 stator cores 121n, in the configuration of the present invention, the width of each stator core 121n in the circumferential direction A (pole width of the stator 12) is a central angle of 10° (=15°-5°). On the other hand, in the conventional configuration where there are 24 stator cores 121n, the width of each stator core 121n in the circumferential direction A is generally a central angle of 7.5° (=15° / 2). Therefore, in the conventional configuration, since the maximum torque point is 8 poles (=24 / 3), the range in which the maximum torque is generated is 60° (=7.5°×8). In contrast, in the configuration of the present invention, since the maximum torque point is 12 poles (=24 / 2), the range in which the maximum torque is generated is 120° (=10°×12). Therefore, the configuration of the present invention can obtain a larger torque than the conventional configuration. The number of pole pairs Pn can be cited as a parameter that affects the increase in torque. The number of pole pairs Pn is 1 / 2 the value of the number of poles. Therefore, for example, in the case of a 24-pole machine having 24 stator cores 121n, the number of pole pairs Pn in the conventional configuration is 4 (=(24 / 3) / 2). In contrast, the number of pole pairs Pn in the configuration of the present invention is 6 (=(24 / 2) / 2). Therefore, the configuration of the present invention can obtain 1.5 times the torque as the conventional configuration.

[0023] Moreover, in the rotating electric machine 10 according to this embodiment, each stator core 121n has two pole opposing surfaces 12S (first pole opposing surface 12Sa and second pole opposing surface 12Sb) facing the rotor 11. Furthermore, in the rotating electric machine 10, each rotor core 111n is configured to have two pole opposing surfaces 11S (third pole opposing surface 11Sa and fourth pole opposing surface 11Sb) facing the stator 12. With this configuration, the area of ​​the pole opposing surface 12S of the stator 12 that generates torque is larger than in the conventional configuration. In the configuration of the present invention, there are two pole opposing surfaces. On the other hand, in the conventional configuration, there is one pole opposing surface. Therefore, the configuration of the present invention can obtain twice the torque of the conventional configuration.

[0024] As described above, the rotating electric machine 10 according to this embodiment can increase the torque while maintaining the size of the device. In other words, a rotating electric machine of the same size can achieve a high volume ratio.

[0025] (Pole forming part) FIG. 3 is a diagram showing the shape of the winding portion of the first pole forming portion of the stator 12 according to this embodiment. As described above, the first pole forming portion of the stator 12 according to this embodiment is each stator core 121n. Each stator core 121n has a portion (winding portion) where each winding Wn is arranged, and the connecting portion 121c of the stator core 121n corresponds to this portion. The shape of the vertical cross section (vertical cross section with respect to the rotation axis C) of the winding portion does not have to be rectangular. As shown in FIG. 3, it may be trapezoidal, for example. In the case of a trapezoidal shape, the length of the far side of the winding portion is longer than the length of the side closer to the rotation axis C. In other words, the trapezoidal winding portion spreads in the radial direction B. FIG. 4 is a diagram showing the shape of the first pole forming portion of the stator 12 according to this embodiment. In the stator core 121n according to this embodiment, the pole facing surface 12S facing the rotor 11 does not have to be linear. As shown in FIG. 4, it may be arcuate, for example.

[0026] Moreover, each pole-forming portion (first and second pole-forming portions) of the stator 12 and the rotor 11 is each stator core 121n and each stator core 111n. These portions may be formed, for example, not only from silicon steel plates, but also by laminating electromagnetic steel plates that may or may not contain silicon.

[0027] (coil space) The coil space WS is provided in each stator core 121n as a space for arranging the winding Wn that can secure a necessary magnetomotive force by a predetermined current. When the coil space WS is made large, it is preferable to provide the coil space WS horizontally along the rotation axis direction Y of the rotating electric machine 10 from the viewpoint of suppressing an increase in the overall length and volume.

[0028] (Three-dimensional magnetic path using transverse magnetic flux) 5A and 5B are diagrams (part 1 and part 2) showing a magnetic path MP generated between the rotor 11 and the stator 12 according to the present embodiment. FIG. 5A shows an example of the magnetic path MP generated between the rotor 11 and the stator 12 as viewed from the horizontal direction X relative to the rotation axis C of the rotating electric machine 10. FIG. 5B shows an example of the magnetic path MP generated between the rotor 11 and the stator 12 as viewed from the rotation axis direction Y of the rotating electric machine 10. The rotor 11 and the stator 12 are configured to generate a ring-shaped three-dimensional magnetic path MP as shown in FIG. 5A and FIG. 5B. In order to generate such a three-dimensional magnetic path MP, it is first necessary to generate a transverse magnetic flux (magnetic flux in the rotation axis direction). Therefore, in the rotating electric machine 10, each winding Wn installed on the stator 12 is configured to be located approximately at the center in the rotation axis direction Y of each stator core 121n. As a result, in the rotating electric machine 10, when a current flows through the winding Wn of the stator 12, a magnetic flux in the direction of the rotation axis Y, i.e., a horizontal magnetic flux, is generated. Furthermore, in order to generate the above-mentioned three-dimensional magnetic path MP, it is necessary to form a ring-shaped magnetic path using vertical and horizontal magnetic flux. Therefore, in the rotating electric machine 10, each winding Wn installed in the stator 12 is provided so as to be positioned between two permanent magnets Mn installed in the rotor 11, and the poles of the stator 12 and the poles of the rotor 11 are configured to face each other. Furthermore, in the rotating electric machine 10, in one rotor core 111n, the magnetic field directions (positions of the S pole and the N pole) of the two permanent magnets Mn (the first permanent magnet Ma and the second permanent magnet Mb) are configured to be opposite to each other. In other words, in the rotor 11, the positions of the S pole and the N pole of the permanent magnet Mn are configured to be opposite to each other in the direction of the rotation axis Y. As shown in FIG. 5B, in the stator 12, every other winding Wn is reversely connected, so that the direction of the magnetic field in the circumferential direction A is different.

[0029] In this way, the rotating electric machine 10 according to the present embodiment can further increase the torque by utilizing the three-dimensional magnetic path MP having the above characteristics and by using the magnet torque Te and the reluctance torque Tr in combination. In other words, a rotating electric machine of the same size can achieve a higher volume ratio. One of the factors that determine the efficiency of a rotating electric machine is the length of the magnetic path. In the configuration of the present invention, the ratio of the number of poles Psn of the stator 12 to the number of poles Prn of the rotor 11 is 2:1. In the configuration of the present invention, fewer magnetic paths are generated and the length of the magnetic path is shorter than in the conventional configuration in which the ratio of the number of poles Psn of the stator 12 to the number of poles Prn of the rotor 11 is 3:1. Therefore, the magnetic resistance is small, which acts to increase the torque. The magnet torque Te is a torque generated by attraction and repulsion between the poles of the rotating magnetic field of the stator 12 and the magnetic poles of the permanent magnet Mn of the rotor 11. The reluctance torque Tr is generated only by the attractive force between the poles of the rotating magnetic field of the stator 12 and the salient poles of the rotor 11.

[0030] (torque curve) Fig. 6 is a diagram showing the relationship between torque and current phase angle (torque curve) in a typical interior permanent magnet synchronous motor (IPMSM). In Fig. 6, the horizontal axis shows current phase angle β [unit: °], and the vertical axis shows various torques (magnet torque Te, reluctance torque Tr, composite torque T (= Te + Tr) [unit: %]) and voltage Va [unit: %]. In the example shown in Fig. 6, the current phase angle β is shown to range from -30° to +90°.

[0031] As shown in FIG. 6, the magnet torque Te is zero when the current phase angle β is +90°, and is the maximum positive value when the current phase angle β is 0°. On the other hand, the reluctance torque Tr is the maximum positive value when the current phase angle β is 45°, and is zero when the current phase angle β is 0° or +90°. Due to this relationship, the various torques Te, Tr, and T can be controlled by changing the current phase angle β. Therefore, in order to output the maximum torque, it is sufficient to control the current so that a three-dimensional magnetic path MP (composite magnetic field) between each stator core 121n and each rotor 111n is generated at a position where the sum of the magnet torque Te and the reluctance torque Tr is maximized (the composite torque T is maximized).

[0032] FIG. 7 is a diagram showing the relationship (torque curve) between the torque and the current phase angle in the rotating electric machine 10 according to this embodiment. As shown in FIG. 7, the rotating electric machine 10 is configured so that the reluctance torque Tr is a positive maximum value when the current phase angle β is 0°, and is zero when the current phase angle β is -30° or +30°. In other words, when the current phase angle β is 0°, both the magnet torque Te and the reluctance torque Tr are positive maximum values, and the composite torque is also maximum. The rotating electric machine 10 is also configured so that the maximum value of the reluctance torque Tr is substantially the same as the maximum value of the magnet torque Te. Therefore, the composite torque in the rotating electric machine 10 is approximately twice as large as that in the conventional configuration.

[0033] (two-phase control) The rotating electric machine 10 according to this embodiment employs two-phase control (control by two-phase AC) as the control means of the above configuration. FIG. 8 is a diagram showing a control system 1 (drive circuit) of the rotating electric machine 10 according to this embodiment. As shown in FIG. 8, the control system 1 mainly includes a switching circuit 2, a gate bridge circuit 3, and a power supply 4. The switching circuit 2 is, for example, a bridge circuit (inverter) having four switching elements Sn (S1-S4) and four circulating diodes Dn (D1-D4). The bridge circuit is composed of two half-bridge circuits. The half-bridge circuit is composed of one leg having two arms each of which is composed of one switching element Sn and one circulating diode Dn connected in anti-parallel to the switching element Sn. In the switching circuit 2, the power supply 4 switches the winding Wn through which the current flows by switching on and off each switching element Sn. The gate bridge circuit 3 is a circuit that controls the driving of each switching element Sn of the switching circuit 2. The gate bridge circuit 3 controls the driving of each switching element Sn by transmitting an ON or OFF command (control signal) to the element.

[0034] Specifically, when an ON signal is sent from the gate bridge circuit 3 to the switching elements S1 and S4 and an OFF signal is sent from the gate bridge circuit 3 to the switching elements S2 and S3, the switching circuit 2 forms a first circuit of the power source 4 → switching element S1 → rotating electric machine 10 → switching element S4 → power source 4. When an ON signal is sent from the gate bridge circuit 3 to the switching elements S2 and S3 and an OFF signal is sent from the gate bridge circuit 3 to the switching elements S1 and S4, the switching circuit 2 forms a second circuit of the power source 4 → switching element S3 → rotating electric machine 10 → switching element S2 → power source 4. If a voltage with a positive amplitude is output in the two circuits formed, a positive current flows. On the other hand, if a voltage with a negative amplitude is output, a negative current flows. In this way, in the rotating electric machine 10, by controlling each switching element Sn, two circuits are formed and two-phase current can be controlled.

[0035] FIG. 9 is a diagram showing an example of control of the rotating electric machine 10 according to this embodiment. The rotating electric machine 10 according to this embodiment is two-phase controlled by the control system 1 having the above configuration. The control system 1 controls the supply of two-phase AC currents (I-phase AC current and II-phase AC current) flowing from the power source 4 to each stator core 121n in a predetermined excitation interval (range of 20° to 30°) by switching control of the switching elements Sn. FIG. 9 shows an example of a control waveform of an output voltage in the case of the excitation interval (range of 20°). The rotating electric machine 10 is configured to use magnet torque Te and reluctance torque Tr in combination. Therefore, in the excitation interval of the rotating electric machine 10, the output voltage for supplying the I-phase AC current and the output voltage for supplying the II-phase AC current are controlled so that torques are generated in the order of "magnet torque Te (repulsion)" → "reluctance torque Tr (attraction)" → "magnet torque Te (attraction)". Here, the above-mentioned "magnet torque Te (repulsion)" refers to the repulsion between the poles of the rotating magnetic field of the stator 12 and the magnetic poles of the permanent magnets Mn of the rotor 11. The above-mentioned "reluctance torque Tr (attraction)" refers to the attraction between the poles of the rotating magnetic field of the stator 12 and the salient poles of the rotor 11. The above-mentioned "magnet torque Te (attraction)" refers to the attraction between the poles of the rotating magnetic field of the stator 12 and the magnetic poles of the permanent magnets Mn of the rotor 11.

[0036] In the control example shown in FIG. 9, the control system 1 outputs a positive voltage to each stator core 121n assigned to the I phase as an output voltage for supplying an I-phase AC current during a time period corresponding to the first excitation interval (20° range). As a result, the pole of each stator core 121n becomes an N pole during the excitation interval, and a magnet torque Te is generated. The control system 1 provides a non-excitation interval (10° range). At this time, a reluctance torque Tr is generated. When the phase of the current is zero, a maximum reluctance torque Tr is generated. After a time period corresponding to the non-excitation interval has elapsed, a negative voltage is output to each stator core 121n assigned to the I phase during a time period corresponding to the second excitation interval (20° range). As a result, the pole of each stator core 121n becomes an S pole during the excitation interval, and a magnet torque Te is generated.

[0037] The control of the II-phase AC current is similar. The control system 1 controls each of the stator cores 121 assigned to the II-phase AC current in a time period corresponding to the third excitation interval (range of 20°) as an output voltage for supplying the II-phase AC current. n+1 This outputs a positive voltage to each stator core 121. n+1 When the time corresponding to the non-excitation interval (range of 10°) has elapsed, the control system 1 controls each of the stator cores 121 assigned to the II phase to have a pole of N pole during the fourth excitation interval (range of 20°). n+1 This causes each stator core 121 to output a negative voltage. n+1 The pole of becomes a south pole during the excitation interval.

[0038] The initial section (5° range) of the first excitation interval in I-phase control overlaps with the final section (5° range) of the third excitation interval in II-phase control. Similarly, the initial section (5° range) of the second excitation interval in I-phase control overlaps with the final section (5° range) of the fourth excitation interval in II-phase control. In this way, a predetermined phase (15° range) is provided between the control period for the supply of I-phase AC current and the control period for the supply of II-phase AC current.

[0039] In this way, the control system 1 alternately controls the supply of I-phase AC current and the supply of II-phase AC current, and switches the pole nature (S pole and N pole) of each stator core 121n. Specifically, the control system 1 switches each stator core 121n assigned to the II phase to the S pole after each stator core 121n assigned to the I phase becomes an N pole. n+1 The pole of each stator core 121n assigned to the I phase becomes an S pole, and then the pole of each stator core 121 assigned to the II phase becomes an S pole. n+1 The supply of I-phase AC current and II-phase AC current is controlled so that the pole of I becomes the N pole. As a result, the magnetic field generated by the excitation rotates, and the rotor 11 rotates in synchronization with the rotation of the magnetic field.

[0040] As described above, in the configuration of the present invention, the control system 1 controls the current supplied to each stator core 121n (each winding Wn) of the rotating electric machine 10 so that a three-dimensional magnetic path MP between each stator core 121n and each rotor 111n is generated at a position where the composite torque T (=Te+Tr) of the magnet torque Te and the reluctance torque Tr is maximized. As a result, in the configuration of the present invention, it is possible to increase the torque while maintaining the size of the device. Therefore, in the configuration of the present invention, a higher volume ratio than the conventional one can be realized, and a rotating electric machine with high output can be provided with the same size (a small rotating electric machine with the same output). Furthermore, according to the configuration of the present invention, since the rotating electric machine 10 is configured to perform two-phase control, a cheaper drive circuit can be used compared to the conventional drive circuit that performs three-phase control, leading to cost reduction.

[0041] <Modification> FIG. 10 is a schematic diagram of a plurality of rotating electric machines 10n according to a modified example. In the configuration shown in FIG. 10, a plurality of rotating electric machines 10n are configured by being connected to the same output shaft 13 (i.e., the rotation axis C). In such a configuration, the first rotating electric machine 101 and the second rotating electric machine 102 may be integrally formed at their contacting portions. FIG. 10 shows an example in which a common permanent magnet Mn is provided in the rotor 111 of the first rotating electric machine 101 and the rotor 112 of the second rotating electric machine 102. When a plurality of rotating electric machines 10n are configured by being connected to each other, a larger torque can be obtained compared to a single rotating electric machine 10.

[0042] The present invention is not limited to the above-mentioned embodiment, modified examples, etc., and various modifications are possible within the scope of the gist of the present invention. In addition, the configurations shown in the embodiment and modified examples can be arbitrarily combined with each other. That is, although the present invention has been described based on the embodiment, it is understood that the present invention is not limited to the embodiment, structure, etc. The present invention also includes various modified examples and modifications within the equivalent range. In addition, various combinations and forms, and even other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present invention. [Explanation of symbols]

[0043] 1 Control system; 10 Rotating electric machines; 11 rotor; 111n rotor core; 12 stator; 121n stator core; Mn permanent magnets; Wn winding.

Claims

1. A rotating electric machine (10), A rotor (11) provided rotatably about a rotation axis (C) and including a plurality of rotor cores (111n) in which a plurality of permanent magnets (Mn) are respectively arranged; a stator (12) provided in a circumferential direction of the rotor and including a plurality of stator cores (121n) on which a plurality of windings (Wn) are respectively arranged; Each rotor core on which each permanent magnet is disposed defines a plurality of poles of the rotor, and each stator core on which each winding is disposed defines a plurality of poles of the stator, A rotating electric machine configured so that a ratio of the number of poles (Psn) of the stator to the number of poles (Prn) of the rotor is Psn:Prn=2:

1.

2. The stator has a first pair of annular structures (12a, 12b) forming the respective stator cores, Each of the stator cores is configured to have a first pair of pole facing surfaces (12Sa, 12Sb) facing the rotor, The rotor has a second pair of annular structures (11a, 11b) forming the rotor cores, 2. The rotating electric machine according to claim 1, wherein each of the rotor cores is configured to have a second pair of pole facing surfaces (11Sa, 11Sb) facing the stator.

3. The first pair of annular structures includes a first annular structure (12a) and a second annular structure (12b), Each of the stator cores is integrally formed by connecting a first core portion (121a) of the first annular structural portion and a second core portion (121b) of the second annular structural portion in a rotation axis direction (Y), each of the windings is disposed at a predetermined position between the first core portion and the second core portion in the rotation axis direction, 3. The rotating electric machine according to claim 2, wherein each of the stator cores is configured to have, as the first pair of pole opposing surfaces against the rotor, a first pole opposing surface (12Sa) which is the surface of the first core portion facing the rotor, and a second pole opposing surface (12Sb) which is the surface of the second core portion facing the rotor.

4. The second pair of annular structures includes a third annular structure (11a) and a fourth annular structure (11b), Each rotor core is integrally formed by connecting a third core portion (111a) of the third annular structural portion and a fourth core portion (111b) of the fourth annular structural portion in a rotation axis direction (Y), The permanent magnets are disposed at predetermined positions of the third core portion and the fourth core portion, 4. The rotating electric motor according to claim 2 or 3, wherein each rotor core is configured to have, as the second pair of pole opposing surfaces against the stator, a third pole opposing surface (11Sa) which is the opposing surface of the third core portion toward the stator, and a fourth pole opposing surface (11Sb) which is the opposing surface of the fourth core portion toward the stator.

5. The rotating electric machine according to claim 1 , wherein each of the windings is disposed so as to be positioned at a center of each of the stator cores in a rotation axis direction (Y).

6. The stator is configured such that the windings arranged on each of the stator cores are alternately connected inversely in the circumferential direction (A), and when two-phase currents flow through the windings and the windings are excited, the directions of the magnetic fields are different; 6. The rotating electric machine according to claim 1, wherein the pole characteristics of each of the stator cores are switched by alternately controlling the supply of current to a first phase and controlling the supply of current to a second phase of the two phases.

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