Rotary electrical machine

Abstract

The purpose of the present invention is to provide a rotary electrical machine with improved customizability. The rotary electrical machine comprises a stator and a rotor that faces the stator with an air gap therebetween. The rotor has a rotor core that has a plurality of magnet air grooves which run axially therethrough and a plurality of magnets that are fixed to the rotor core. The plurality of magnet air grooves include radial magnet air grooves that are disposed near q axes on both sides of a d axis, and a circumferential magnet air groove that is disposed between the radial magnet air grooves and on the radially inner side of the radial magnet air grooves. The radial magnet air grooves and the circumferential magnet air groove are in a U-shaped arrangement. The plurality of magnets each have the same dimensions and the same shape. The plurality of magnets are inserted into at least one of the plurality of magnet air grooves, and the number of the plurality of magnets is in accordance with a speed region to be used.

Description

Rotating electric machines

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

[0002] Interior permanent magnet motors with magnets embedded in the rotor are well known. Patent Document 1 discloses a rotor for a rotating electric machine that uses multiple identically shaped holes for magnet mounting and salient poles to vary the number of poles and the ratio of magnet torque to reluctance torque, thereby improving torque and electrical characteristics and production efficiency. Patent Document 2 also discloses a rotating electric machine that defines the pole arc and embedding depth of a V-shaped magnet arrangement, thereby improving efficiency and reducing magnet usage by simply modifying the rotor shape while keeping the current frame and stator core shape.

[0003] JP 2002-209349 A JP 2014-236577 A

[0004] However, conventional rotating electrical machines have a problem of limited customizability because the range of torque and speed regions in which high power density can be achieved is limited for the same number of poles and a wide range of body sizes.

[0005] Therefore, in the past, there were the following problems: - The target torque and speed ranges were fixed. - Output and efficiency deteriorated relative to the size. - Multiple types of magnets with different dimensions were required for each size. - The rotor structure had to be designed and reviewed each time to suit the size and application. In other words, there was room for improvement in customizability in the past.

[0006] The present invention has been made in view of the above-mentioned points, and has an object to provide a rotating electric machine with improved customizability.

[0007] A rotating electric machine according to one aspect of the present invention includes a stator and a rotor facing the stator across an air gap, the rotor having a rotor core with a plurality of magnet air grooves penetrating in the axial direction, and a plurality of magnets fixed to the rotor core, the plurality of magnet air grooves including radial magnet air grooves arranged near the q-axis on both sides of the d-axis, and circumferential magnet air grooves arranged between the radial magnet air grooves and radially inward of the radial magnet air grooves, the radial magnet air grooves and the circumferential magnet air grooves being arranged in a U-shape, each of the plurality of magnets having the same size and shape, each of the plurality of magnets being inserted into at least one of the plurality of magnet air grooves, and the number of the plurality of magnets being a number according to the speed range used.

[0008] According to one aspect of the present invention, it is possible to provide a rotating electric machine with improved customizability.

[0009] 1 is a diagram showing a schematic configuration of a motor 100 according to a first embodiment of the present invention. FIG. 1 is a diagram showing a schematic configuration of a motor 101 having the same magnet air groove arrangement as the motor 100 of FIG. 1 but with a reduced number of magnets. FIG. 2 is a diagram showing a schematic configuration of a motor 1100 having a different magnet air groove arrangement than the motor 100 of FIG. 1. FIG. 3 is a diagram showing the rotational speed-torque characteristics of the motors shown in FIGS. 1, 2, and 3. FIG. 4 is a diagram showing the rotational speed-efficiency characteristics of the motors shown in FIGS. 1, 2, and 3. FIG. 4 is a diagram showing a schematic configuration of a motor 2100 according to a second embodiment of the present invention. FIG. 5 is a diagram showing a schematic configuration of a motor 2101 having the same magnet air groove arrangement as the motor 2100 of FIG. 6 but with a reduced number of magnets. FIG. 6 is a diagram showing a schematic configuration of a motor 2102 having the same magnet air groove arrangement as the motor 2100 of FIG. 6 but with a reduced number of magnets. FIG. 7 is a diagram explaining the dimensions of the motors shown in FIGS. 6, 7, and 8. FIG. 5 is a diagram showing a schematic configuration of a motor 3100 according to a second embodiment of the present invention. FIG. 6 is a diagram showing a schematic configuration of a motor 4100 according to the second embodiment of the present invention. FIG. 7 is a diagram showing the efficiency characteristics of a motor by number of magnets. 14 is a table showing the number of magnets that will result in high efficiency in each speed range of the motor's rotational speed for each polar arc degree. FIG. 15 is a diagram showing the efficiency characteristics that can be achieved by a rotor core set to the number of magnets that will result in high efficiency in each speed range of the motor's rotational speed for each polar arc degree. FIG. 16 is a table showing the number of magnets that will result in high efficiency in each speed range of the motor's rotational speed for each parameter A. FIG. 17 is a diagram explaining the magnetization of each magnet. FIG. 18 is a diagram showing the magnetic field applied to each magnet.

[0010] Hereinafter, a rotating electric machine according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, the scale and number of components may differ from the actual structure in order to make each component easier to understand.

[0011] First Embodiment FIG. 1 is a diagram illustrating a schematic configuration of a motor 100 according to a first embodiment of the present invention. FIG. 1 is a schematic diagram of the motor 100 as viewed from a direction parallel to a central axis J, which is the center of the rotational shaft of the motor 100. FIG. 1 is a diagram illustrating a sectorial cutaway view of one pole of the entire motor 100, showing a range including both adjacent q axes in a shape symmetrical about the d axis. In this embodiment, the motor 100 is described using an 8-pole, 48-slot motor as an example. However, the present invention is not limited to this, and can also be applied to motors with eight or more magnetic poles. Since the rotor area per pole changes depending on the number of magnetic poles, the motor is designed within the dimensional constraints described below.

[0012] Hereinafter, the direction parallel to the central axis J will be referred to as the axial direction. In the axial direction, the side extending toward the front from the plane of FIG. 1 will be referred to as the "one side," and the side extending away from the plane of FIG. 1 will be referred to as the "other side." Note that the terms "one side" and "other side" are names used merely for the purpose of explanation and do not limit the actual positional relationship or direction. Furthermore, unless otherwise specified, the radial direction centered on the central axis J will be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, will be simply referred to as the "circumferential direction." In the radial direction, the side closer to the central axis J will be referred to as the "radially inner side," and the side away from the central axis J will be referred to as the "radially outer side." In the circumferential direction, the clockwise side when viewed from one axial side will be referred to as the "one circumferential side," and the counterclockwise side will be referred to as the "other circumferential side."

[0013] In this specification, "extending in the axial direction" includes not only extending strictly in the axial direction but also extending in a direction tilted by less than 45° with respect to the axial direction. In addition, in this specification, "extending in the radial direction" includes not only extending strictly in the radial direction, i.e., in a direction perpendicular to the axial direction, but also extending in a direction tilted by less than 45° with respect to the radial direction. Furthermore, "parallel" includes not only being strictly parallel but also being tilted by an angle of less than 45° with respect to the direction perpendicular to the axial direction. Furthermore, "extending in a direction perpendicular to the axial direction" includes not only extending in a direction strictly perpendicular to the axial direction but also extending in a direction tilted by less than 45° with respect to the direction perpendicular to the axial direction.

[0014] The motor 100 is an example of a rotating electric machine. The motor 100 is an 8-pole, 48-slot motor. The motor 100 includes a stator 200, a rotor 300 disposed radially inward of the stator 200 and facing the stator 200 with an air gap therebetween, and a shaft 500 fixed to the rotor 300 and extending along a central axis J. The shaft 500 is the rotation axis of the motor 100.

[0015] The stator 200 has a stator core 201 and a stator coil 204. The stator core 201 has a core back portion 202 and teeth portions 203 that extend radially inward of the core back portion 202 and are arranged at equal intervals in the circumferential direction. The stator core 201 has slots 205 between the teeth portions 203. The stator coil 204 is housed in the slots 205 and wound around the teeth portions 203.

[0016] The rotor 300 includes a rotor core 301 and magnets 401, 402, and 403. The rotor core 301 has magnet air grooves 311, 312, and 313 that penetrate the rotor core 301 in the axial direction. The magnet air grooves 311 and 312 are disposed on the rotor core 301, respectively, on both sides of the d-axis toward the q-axis. These magnet air grooves disposed on both sides of the d-axis toward the q-axis are called radial magnet air grooves. The magnet air groove 313 is disposed circumferentially between the magnet air grooves 311 and 312, radially inward of the magnet air grooves 311 and 312, on the rotor core 301. The magnet air groove disposed between the radial magnet air grooves and radially inward of the radial magnet air groove is called a circumferential magnet air groove. The arrangement of the magnet air grooves 311, 312, and 313 resembles the Japanese katakana character U, and is therefore referred to as a U-shaped arrangement. Rotor core 301 is formed by stacking electromagnetic steel sheets in the axial direction. Note that, hereinafter, magnets inserted into the radial magnet air grooves and arranged so that their longitudinal direction is along the radial direction are referred to as radially arranged magnets. Also, magnets inserted into the circumferential magnet air grooves and arranged so that their longitudinal direction is along a direction perpendicular to the radial direction are referred to as circumferentially arranged magnets. In FIG. 1 , magnets 401 and 402 are radially arranged magnets, and magnet 403 is a circumferentially arranged magnet.

[0017] Magnet 401 is inserted into magnet air groove 311 and fixed to rotor core 301 with, for example, an adhesive. Magnet 402 is inserted into magnet air groove 312 and fixed to rotor core 301 with, for example, an adhesive. Magnet 403 is inserted into magnet air groove 313 and fixed to rotor core 301 with, for example, an adhesive. In this embodiment, magnets 401, 402, and 403 have the same size and shape, and are housed one each in magnet air grooves 311, 312, and 313. When magnet 401 is housed in magnet air groove 311, there are gaps on both sides of magnet 401 that function as flux barriers 351. When magnet 402 is housed in magnet air groove 312, there are gaps on both sides of magnet 402 that function as flux barriers 352. Magnet air groove 313 has gaps that function as flux barriers 353 on both sides of magnet 403 when magnet 403 is housed therein.

[0018] Figure 2 is a diagram showing the schematic configuration of a motor 101 that has the same magnet air groove arrangement as the motor 100 of Figure 1 but has a reduced number of magnets. In the motor 101 of Figure 2, components similar to those of the motor 100 of Figure 1 are given the same reference numerals, and detailed descriptions will be omitted. The motor 101 is an example of a rotating electric machine. The motor 101 is an 8-pole, 48-slot motor. The motor 101 has a stator 200, a rotor 300 disposed radially inward of the stator 200 and facing it with an air gap between them, and a shaft 500 fixed to the rotor 300 and extending along a central axis J.

[0019] In motor 101, rotor 300 has rotor core 301 and magnets 401 and 402. Magnet 401 is inserted into magnet air groove 311 and fixed to rotor core 301 with, for example, an adhesive. Magnet 402 is inserted into magnet air groove 312 and fixed to rotor core 301 with, for example, an adhesive. Motor 101 in Figure 2 differs from motor 100 in Figure 1 in that it does not have magnet 403. In motor 101, magnet air groove 313 does not contain a magnet, so magnet air groove 313 as a whole functions as flux barrier 353.

[0020] Motor 100, in which the same magnet is inserted into all magnet air grooves as in Figure 1, can be used in the low-speed, high-torque range, while motor 101, in which no magnet is inserted into magnet air groove 313 and flux barrier 353 is used as in Figure 2, can be used in the high-speed, low-torque range. This point will be explained below in comparison with the comparative example in Figure 3.

[0021] Figure 3 is a diagram showing the schematic configuration of a motor 1100, which has a different arrangement of magnet air grooves than the motor 100 of Figure 1. In the motor 1100 of Figure 3, components similar to those of the motor 100 of Figure 1 are given the same reference numerals, and detailed description will be omitted. The motor 1100 is an 8-pole, 48-slot motor. The motor 1100 has a stator 200, a rotor 1300 disposed radially inward of the stator 200 and facing it across an air gap, and a shaft 500 fixed to the rotor 1300 and extending along a central axis J.

[0022] Rotor 1300 has rotor core 1301 and magnets 1401 and 1402. Rotor core 1301 has magnet air grooves 1311 and 1312 that penetrate in the axial direction. Magnet air grooves 1311 and 1312 are arranged in rotor core 1301 so that they are spaced apart from each other on the radially outer side and close to each other on the radially inner side. The arrangement of magnet air grooves 1311 and 1312 resembles the letter V, and is therefore referred to as a V-shaped arrangement. Magnet 1401 is inserted into magnet air groove 1311 and fixed to rotor core 1301, for example, with an adhesive. Magnet 1402 is inserted into magnet air groove 1312 and fixed to rotor core 301, for example, with an adhesive. Motor 1100 has the same physical size as motor 100 in FIG. 1 . Magnets 1401 and 1402 have the same size and shape, and are housed one in each of magnet air grooves 1311 and 1312. Magnet air groove 1311 has a gap that functions as flux barrier 1351 when magnet 1401 is housed therein. Magnet air groove 1312 has a gap that functions as flux barrier 1352 when magnet 1402 is housed therein.

[0023] In the case of the rotor structure (rotor 300) of this embodiment, compared to rotor 1300 (see Figure 3) with the same size and number of poles and a V-shaped magnet arrangement, it is possible to use more magnets of the same size per pole, as in the model of Figure 1 (three magnets arranged in a U-shaped magnet air groove). As a result, the magnetomotive force increases, which improves torque when the input current is the same, making it possible to design an optimal amount of magnetic flux for the large torque range.

[0024] Additionally, the model in Figure 2 (two magnets placed in a U-shaped magnet air groove) uses the magnet air groove without a magnet inserted as a flux barrier. Because the magnetic permeability of air and magnets is nearly equal, the magnetic path does not change in the model in Figure 2, making it possible to suppress the magnetomotive force, enabling an optimal design for the amount of magnetic flux aimed at high speeds.

[0025] FIG. 4 is a diagram showing the rotational speed-torque characteristics of the motors shown in FIGS. 1, 2, and 3. FIG. 4 is a graph showing the characteristics of each motor under conditions where the input current and limit voltage are the same, with the horizontal axis representing rotational speed and the vertical axis representing torque. As shown in FIG. 4, motor 100 of FIG. 1 has a wider range of NT region compatibility than motor 1100 of FIG. 3, resulting in a rotor structure that allows for high torque. Therefore, according to this embodiment, it is possible to adjust the output and rotational speed to match the specifications.

[0026] FIG. 5 is a graph showing the rotational speed-efficiency characteristics of the motors shown in FIGS. 1, 2, and 3. FIG. 5 is a graph showing the characteristics of each motor under the same output conditions, with the horizontal axis representing rotational speed and the vertical axis representing efficiency. Compared to the model of FIG. 3 (two magnets arranged in a V-shaped magnet air groove), the model of FIG. 1 (three magnets arranged in a U-shaped magnet air groove) achieves high efficiency mainly in the low rotation range by reducing copper loss due to reduced current density. Meanwhile, the model of FIG. 2 (two magnets arranged in a U-shaped magnet air groove) shows almost the same tendency as the model of FIG. 3 (two magnets arranged in a V-shaped magnet air groove). As described above, according to this embodiment, it is possible to switch between the characteristics of the large torque region in the low rotation range and the characteristics of the V-shaped structure in the high rotation range by changing the magnet arrangement.

[0027] The first embodiment described above has the following advantages: - By using multiple magnets of the same size, it is possible to accommodate a wide range of body sizes and apply a magnet structure that can achieve high output and high efficiency. - By inserting or removing magnets in the magnet air grooves, it is possible to adjust the balance between magnetic flux and current, making it possible to manufacture the same rotor core to achieve the conflicting characteristics of high torque and high speed.

[0028] <Embodiment 2> Fig. 6 is a diagram showing the schematic configuration of a motor 2100 according to embodiment 2 of the present invention. In the motor 2100 in Fig. 6, the same components as those in the motor 100 in Fig. 1 are given the same reference numerals, and detailed description thereof will be omitted.

[0029] The motor 2100 is an example of a rotating electric machine. The motor 2100 is an 8-pole, 48-slot motor. The motor 2100 includes a stator 200, a rotor 2300 disposed radially inside the stator 200 and facing the stator 200 with an air gap therebetween, and a shaft 500 fixed to the rotor 2300 and extending along a central axis J.

[0030] Rotor 2300 has rotor core 2301 and magnets 2401, 2402, 2403, 2404, and 2405. Rotor core 2301 has magnet air grooves 2311, 2312, 2313, 2314, and 2315 that run through it in the axial direction. Magnet air grooves 2311, 2312, 2313, and 2314 are respectively arranged in rotor core 2301 on both sides of the d-axis, closer to the q-axis. Magnet air groove 2313 is arranged on the same radial axis as magnet air groove 2311. Magnet air groove 2313 is arranged radially inward of magnet air groove 2311. Magnet air groove 2314 is arranged on the same radial axis as magnet air groove 2312. Magnet air groove 2314 is arranged radially inward of magnet air groove 2312. Furthermore, magnet air groove 2315 is disposed circumferentially between magnet air groove 2313 and magnet air groove 2314 in rotor core 2301, and radially inward of magnet air grooves 2313 and 2314. The arrangement of magnet air grooves 2311, 2312, 2313, 2314, and 2315 resembles the Japanese katakana character U, and is therefore referred to as a U-shaped arrangement. In Figure 1, magnets 2401, 2402, 2403, and 2404 are radially arranged magnets, and magnet 2405 is a circumferentially arranged magnet.

[0031] Magnet 2401 is inserted into magnet air groove 2311 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2402 is inserted into magnet air groove 2312 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2403 is inserted into magnet air groove 2313 and fixed to rotor core 301 with, for example, an adhesive. Magnet 2404 is inserted into magnet air groove 2314 and fixed to rotor core 301 with, for example, an adhesive. Magnet 2405 is inserted into magnet air groove 2315 and fixed to rotor core 301 with, for example, an adhesive. In this embodiment, magnets 2401, 2402, 2403, 2404, and 2405 have the same size and shape, and are housed one in each of magnet air grooves 2311, 2312, 2313, 2314, and 2315.

[0032] Figure 7 is a diagram showing the schematic configuration of motor 2101, which has the same magnet air groove arrangement as motor 2100 in Figure 6 but has a reduced number of magnets. In motor 2101 in Figure 7, components similar to those in motor 2100 in Figure 6 are assigned the same reference numerals, and detailed descriptions will be omitted. Motor 2101 is an example of a rotating electric machine. Motor 2101 is an 8-pole, 48-slot motor. Motor 2101 has stator 200, rotor 2300 disposed radially inward of stator 200 facing it with an air gap between them, and shaft 500 fixed to rotor 2300 and extending along central axis J.

[0033] In motor 2101, rotor 2300 has rotor core 2301 and magnets 2401, 2402, 2403, and 2404. Magnet 2401 is inserted into magnet air groove 2311 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2402 is inserted into magnet air groove 2312 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2403 is inserted into magnet air groove 2313 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2404 is inserted into magnet air groove 2314 and fixed to rotor core 2301 with, for example, an adhesive. Motor 2101 in FIG. 7 differs from motor 2100 in FIG. 6 in that it does not have magnet 2405. In motor 2101 , magnet air groove 2315 does not contain a magnet, so magnet air groove 2315 functions as a flux barrier 2355 as a whole.

[0034] Figure 8 is a diagram showing the schematic configuration of motor 2102, which has the same magnet air groove arrangement as motor 2100 in Figure 6 but has a reduced number of magnets. In motor 2102 in Figure 8, components similar to those in motor 2100 in Figure 6 are given the same reference numerals, and detailed descriptions will be omitted. Motor 2102 is an example of a rotating electric machine. Motor 2102 is an 8-pole, 48-slot motor. Motor 2102 has stator 200, rotor 2300 disposed radially inward of stator 200 facing it with an air gap between them, and shaft 500 fixed to rotor 2300 and extending along central axis J.

[0035] In motor 2102, rotor 2300 has rotor core 2301 and magnets 2401, 2402, and 2405. Magnet 2401 is inserted into magnet air groove 2311 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2402 is inserted into magnet air groove 2312 and fixed to rotor core 2301 with, for example, an adhesive. Magnet 2405 is inserted into magnet air groove 2315 and fixed to rotor core 2301 with, for example, an adhesive. Motor 2102 in FIG. 8 differs from motor 2100 in FIG. 6 in that it does not have magnets 2403 and 2404. In motor 2102, magnet air grooves 2313 and 2314 do not contain magnets, and therefore magnet air grooves 2313 and 2314 entirely function as flux barriers 2353 and 2354, respectively.

[0036] Motor 2100, in which the same magnet is inserted into all magnet air grooves as shown in Figure 6, can be used in the low-speed, high-torque range. Motor 2101, in which no magnet is inserted into magnet air groove 2315 and flux barrier 2355 is used as shown in Figure 7, can be used in the medium-speed, medium-torque range. Motor 2102, in which no magnet is inserted into magnet air grooves 2313 and 2314 and flux barriers 2353 and 2354 are used as shown in Figure 8, can be used in the high-speed, low-torque range.

[0037] FIG. 9 is a diagram explaining the dimensions of the motors shown in FIGS. 6, 7, and 8. The rotor structure of this embodiment, as shown in FIG. 9, has an arrangement that improves the effect of switching and adjusting each region by adjusting the angle of the magnet air grooves relative to the d-axis and the radial embedding depth of the magnets. The detailed arrangement is configured based on the following considerations: (a) When the electrical angle between the d-axis and the end of the radially arranged magnet on the d-axis side and the air gap side (radially outer side) of the magnet is θmp, with respect to the origin, the arrangement satisfies 0.250π≦θmp≦0.4π. (b) The arrangement satisfies 0.3≦A(=Y / m)≦0.8, where A is the ratio of the radial embedding depth m of the magnet air grooves to the radial length Y of the core back portion 202 of the stator 200. (c) The arrangement satisfies B(=w / t)≧1.5, where B is the ratio of the dimension (bridge width) w between the magnet air grooves to the thickness t of the electromagnetic steel sheets laminated as the rotor core. (d) When the spatial angle between the radially arranged magnet and the d-axis is the magnet angle Θmd, and the spatial angle between the q-axis and the d-axis is Θqd, this is an arrangement in which Θmd≧Θqd. (e) An arrangement in which the longitudinal direction of the circumferentially arranged magnet is perpendicular to the d-axis. (f) When there are multiple radially arranged magnets and circumferentially arranged magnets, the angle between each radially arranged magnet is ≈180°, and the angle between each circumferentially arranged magnet is ≈180°, that is, an arrangement in which the radially arranged magnets are parallel to each other and the circumferentially arranged magnets are parallel to each other.

[0038] The bridge width w between each magnet does not have to be the same as the bridge width between other magnets. Also, the bridge portions between the magnets are linear, parallel bridges, and flux barriers are used to reduce the iron plate portions between the magnets, preventing magnetic flux (leakage flux) from looping between the inner and outer peripheries of the magnets.

[0039] For the model with 0.45≦A≦0.55, the number of magnet air grooves and the maximum number of magnets that can be placed is 5, as shown in Figure 6. For the model with A≧0.60, the number of magnet air grooves and the maximum number of magnets that can be placed is 3, as shown in Figure 10. For the model with A≦0.30, the number of magnet air grooves and the maximum number of magnets that can be placed is 7, as shown in Figure 11.

[0040] Fig. 10 is a diagram showing a schematic configuration of a motor 3100 according to embodiment 2 of the present invention. In the motor 3100 of Fig. 10, components similar to those of the motor 2100 of Fig. 6 are given the same reference numerals, and detailed description thereof will be omitted.

[0041] The motor 3100 is an example of a rotating electric machine. The motor 3100 is an 8-pole, 48-slot motor. The motor 3100 includes a stator 200, a rotor 3300 disposed radially inside the stator 200 and facing the stator 200 with an air gap therebetween, and a shaft 500 fixed to the rotor 3300 and extending along a central axis J.

[0042] Rotor 3300 has rotor core 3301 and magnets 3401, 3402, and 3405. Rotor core 3301 has magnet air grooves 3311, 3312, and 3315 that run through it in the axial direction, and flux barrier air grooves 3313 and 3314. Flux barrier air grooves 3313 and 3314 are too small in size to accommodate magnets 3401, 3402, and 3405. Flux barrier air grooves 3313 and 3314 function as flux barriers 3353 and 3354. In FIG. 10 , magnets 3401 and 3402 are radially arranged magnets, and magnet 3405 is a circumferentially arranged magnet.

[0043] In motor 3100 of Fig. 10, air grooves for flux barriers are provided between the magnet air grooves. Motor 3100 of Fig. 10 has an air groove arrangement for comparing a pattern where 0.6≦parameter A and a pattern where parameter A≦0.6. When the distance between magnets is wide, as in Fig. 10, there is a lot of leakage flux (magnetic flux that loops between the inner and outer periphery of the magnet), so to prevent leakage flux, air grooves for flux barriers are provided between the magnets to be used only as flux barriers. In other patterns (such as five or seven magnet insertion grooves), air grooves for flux barriers may also be provided between magnets when the distance between magnets is wide.

[0044] Fig. 11 is a diagram showing a schematic configuration of a motor 4100 according to embodiment 2 of the present invention. In the motor 4100 of Fig. 11, components similar to those of the motor 2100 of Fig. 6 are given the same reference numerals, and detailed description thereof will be omitted.

[0045] The motor 4100 is an example of a rotating electric machine. The motor 4100 is an 8-pole, 48-slot motor. The motor 4100 includes a stator 200, a rotor 4300 disposed radially inside the stator 200 and facing the stator 200 with an air gap therebetween, and a shaft 500 fixed to the rotor 4300 and extending along a central axis J.

[0046] The rotor 4300 has a rotor core 4301, and magnets 4401, 4402, 4403, 4404, 4405, 4406, and 4407. The rotor core 4301 has magnet air grooves 4311, 4312, 4313, 4314, 4315, 4316, and 4317 that penetrate in the axial direction. In Fig. 11, the magnets 4401, 4402, 4403, 4404, 4405, and 4406 are radially arranged magnets, and the magnet 4407 is a circumferentially arranged magnet.

[0047] FIG. 12 is a graph showing motor efficiency characteristics by number of magnets. FIG. 12 is a graph showing motors with three, four, and five magnets, with the horizontal axis representing rotational speed and the vertical axis representing efficiency. As shown in FIG. 12, the five-magnet model (motor 2100 in FIG. 6) achieves maximum efficiency improvement in the low-speed range. The four-magnet model (motor 2101 in FIG. 7) achieves efficiency improvement compared to models with other magnet counts in the medium-speed range. The three-magnet model (motor 2102 in FIG. 8) expands the high-efficiency range in the high-speed range.

[0048] The second embodiment described above has the following advantages: The arrangement that maximizes the effect of the U-shaped magnet arrangement and maximizes the switching function alleviates magnetic saturation on the d-axis air gap side or near the q-axis, and a magnetic path is formed throughout the rotor core, thereby achieving an expansion of the high-efficiency region.

[0049] Furthermore, the effect of switching and adjusting the number of magnets according to each speed range in the rotor structure of this embodiment is that the following actions and operations occur depending on the arrangement of the magnet air grooves according to the above-mentioned polar arc degree θmp and parameter A.

[0050] (1) Efficiency improvement by polar arc degree θmp Figure 13 is a table showing the number of magnets required for high efficiency in each speed range of the motor rotation speed for each polar arc degree θmp. In Figure 13, the polar arc degree θmp [deg] is specified vertically, and the motor rotation speed [min] is specified horizontally. －１ In other words, in FIG. 13, when the polar arc degree θmp is 0.250π [deg], the rotation speed of the motor is 500 to 3000 [min －１ ], the model with five magnets is highly efficient. Also, in Figure 13, when the polar arc degree θmp is 0.300π [deg], the motor rotation speed is 500 to 2500 [min －１ ], the model with five magnets is highly efficient.

[0051] 14 is a graph showing the efficiency characteristics achievable by the rotor core set to the number of magnets for high efficiency in FIG. 13, for each polar arc degree θmp. FIG. 14 is a graph showing the cases where the polar arc degree θmp is 0.250π [deg], 0.300π [deg], 0.350π [deg], and 0.400π [deg], with the horizontal axis representing the rotation speed and the vertical axis representing the efficiency. For example, in the curve in FIG. 14 where the polar arc degree θmp is 0.250π [deg], the efficiency is high when the motor rotation speed is between 500 and 3000 [min －１ ] shows the efficiency of the model with five magnets in the low speed range, and the motor rotation speed is 3500 to 5500 [min －１ ] shows the efficiency of the model with four magnets in the medium speed range, and the motor rotation speed is 6000 to 8000 [min －１ ] shows the efficiency of the three magnet model in the high speed region.

[0052] The model with polar arc degree θmp≦0.250π has a 3000 to 5000 [min] difference compared to the model with 0.250π≦polar arc degree θmp≦0.40π. －１ ] has a slight improvement in efficiency in the medium speed range, but is less efficient in other speed ranges, so it has little customizability as a rotor core.

[0053] In the model with 0.250π≦pole arc degree θmp≦0.40π, magnetic saturation on the d-axis air gap side or near the q-axis is alleviated by bringing the magnets closer together, reducing iron loss, which is energy loss due to magnetization. In addition, the fundamental component of magnetic flux density that contributes to torque is improved, so under the same torque conditions, copper loss is reduced by suppressing current. Therefore, loss suppression achieves a wide range of high efficiency.

[0054] (2) Efficiency Improvement by Parameter A Figure 15 is a table showing the number of magnets that provides high efficiency in each speed range of the motor rotation speed for each parameter A. In Figure 15, parameter A is specified vertically and the motor rotation speed [min －１ In other words, in FIG. 15, when the parameter A is 0.30, the rotation speed of the motor is 500 to 1500 [min －１ ], the model with seven magnets is highly efficient. Also, in FIG. 15, when the parameter A is 0.45, the motor rotation speed is 500 to 3000 [min －１ ], the model with five magnets is highly efficient.

[0055] 16 is a graph showing the efficiency characteristics achievable by the rotor core set to the number of magnets for high efficiency in FIG. 15, for each parameter A. FIG. 16 is a graph showing the cases where parameter A is 0.3, 0.45, 0.55, 0.65, and 0.75, with the horizontal axis representing the rotation speed and the vertical axis representing the efficiency. For example, in the curve in FIG. 16 where parameter A is 0.3, the efficiency is achievable when the motor rotation speed is 500 to 1500 [min －１ ] shows the efficiency of the model with seven magnets in the low speed range, and the motor rotation speed is 2000 to 2500 [min －１ ] shows the efficiency of the six-magnet model in the low-speed region, and the motor rotation speed is 3000 to 5000 [min －１ ] shows the efficiency of the model with five magnets in the medium speed range, and the motor rotation speed is 5500 to 8000 [min －１ ] shows the efficiency of the three magnet model in the high speed region.

[0056] In the model shown in Figure 10 where parameter A ≥ 0.60, the radial depth of the magnet embedding position is shortened, so the number of magnet air grooves and the maximum number of magnets that can be placed are reduced. －１ In the model with parameter A≦0.30 shown in FIG. 11, the number of magnet air grooves and the maximum number of magnets that can be arranged increase, and the efficiency deteriorates in the low to medium speed range below 2000 [min －１ ], the efficiency is slightly improved in a limited speed range below 5000 [min], but the improvement in the maximum efficiency value is not achieved. －１ In the medium to high speed range above this, efficiency deteriorates due to an increase in leakage flux caused by an excessive radial embedding depth of the magnet. From these results, it is preferable that 0.3≦parameter A≦0.8, and more preferably 0.3≦parameter A≦0.6.

[0057] As described above, by selecting a value for the parameter A in the range of 0.3≦parameter A≦0.8 according to the body size, a wide range of high efficiency can be realized.

[0058] (3) As the post-assembly magnetization and dimensional constraint parameter A due to parameter B and magnet angle Θmd decreases and the radial embedding depth m of the magnet air groove increases, magnetization of the magnet after assembly tends to become more difficult. However, the rotor structure of the present invention, as shown in FIG. 17 , has a magnet arrangement that reduces leakage flux and ensures a magnetic path near the q-axis, thereby forming a magnetic path throughout the rotor core. FIG. 17 explains the magnetization of each magnet. FIG. 17 shows how magnets 2401-2405 assembled in rotor 2300 are magnetized by magnetizing yoke 600. In FIG. 17 , the intensity of the magnetic field is represented by the darkness of the color; the darker the color, the stronger the magnetic field generated by magnetizing yoke 600. With the rotor structure of FIG. 17 , all of magnets 2401-2405 are positioned in areas with strong magnetic fields, as shown in FIG. 17 .

[0059] FIG. 18 is a diagram showing the magnetic field applied to each magnet. In FIG. 18, the vertical axis represents the strength of the magnetic field generated by the magnetizing yoke 600, and the horizontal axis represents the longitudinal distance of each magnet. As shown in FIG. 18, a magnetic field three times stronger than the holding force is applied to each magnet, satisfying the required magnetic field, making magnetization possible after assembly. In other words, according to the present invention, multiple magnets inserted into multiple magnet air grooves can be magnetized after assembly. In addition, this magnet arrangement allows for tolerance of dimensional constraints on the shaft and clamp structure, as the circumferentially arranged magnets are not positioned toward the inner diameter side.

[0060] In the present invention, the number of magnet air grooves per pole is preferably 3 to 12.

[0061] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0062] This application claims priority based on Japanese Patent Application No. 2024-125547, filed on August 1, 2024, and incorporates by reference all the contents of said Japanese Patent Application.

[0063] REFERENCE SIGNS LIST 100...motor 200...stator 300...rotor 301...rotor core 500...shaft

Claims

1. A rotating electric machine comprising: a stator; and a rotor facing the stator across an air gap; wherein the rotor has a rotor core having a plurality of magnet air grooves penetrating in the axial direction; and a plurality of magnets fixed to the rotor core; wherein the plurality of magnet air grooves include radial magnet air grooves arranged near the q-axis on both sides of the d-axis, and circumferential magnet air grooves arranged between the radial magnet air grooves and radially inward of the radial magnet air grooves; wherein the radial magnet air grooves and the circumferential magnet air grooves are arranged in a U-shape; wherein each of the plurality of magnets has the same size and shape; wherein each of the plurality of magnets is inserted into at least one of the plurality of magnet air grooves; and wherein the number of the plurality of magnets is a number according to the speed range used.

2. A rotating electric machine according to claim 1, characterized in that, when the electrical angle between the d-axis end of the radially arranged magnet on the d-axis side and the air gap side and the d-axis is θmp, the arrangement satisfies 0.250π≦θmp≦0.4π.

3. The rotating electric machine according to claim 1, characterized in that the stator has a stator core and a stator coil, the stator core has a core back portion and teeth portions extending radially inward of the core back portion and arranged at equal intervals in the circumferential direction, and the parameter A, which is the ratio of the radial embedding depth m of the plurality of magnet air grooves to the radial length Y of the core back portion, is arranged so that 0.3≦A (= Y / m) ≦ 0.

8.

4. A rotating electric machine according to claim 1, characterized in that a parameter B, which is the ratio of the dimension w between the plurality of magnet air grooves to the thickness t of the electromagnetic steel sheets laminated as the rotor core, is arranged so that B (= w / t) ≧ 1.

5.

5. A rotating electric machine according to claim 1, characterized in that the arrangement satisfies Θmd≧Θqd, where Θmd is the spatial angle between the radially arranged magnets and the d axis, and Θqd is the spatial angle between the q axis and the d axis.

6. A rotating electric machine according to claim 1, characterized in that the longitudinal direction of the circumferentially arranged magnets is arranged perpendicular to the d-axis.

7. A rotating electric machine according to claim 1, characterized in that the radially arranged magnets are parallel to each other and the circumferentially arranged magnets are parallel to each other.

8. A rotating electric machine according to claim 1, characterized in that the number of magnetic poles is eight or more.

9. A rotating electric machine according to claim 1, characterized in that the magnets inserted into the magnet air grooves can be magnetized afterwards.

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