Stator and rotating electric machine

Abstract

This rotating electric machine comprises a rotor (400) and a stator (300) which is disposed around the rotor (400), the stator (300) being provided with: a stator core (1); a stator coil (2) wound around the stator core (1); and a plurality of support members (4) that hold the stator coil (2) by being inserted between adjacent turns of the stator coil (2) in a coil end (7) where the stator coil (2) is protruding, and that have a total contact area with the stator coil (2) larger at a coil end tip part (7b) located away from the stator core (1) than at a coil end root part (7a) located close to the stator core (1).

Description

Stator and rotating electric machine

[0001] The present disclosure relates to a stator and a rotating electric machine.

[0002] A rotating electric machine is composed of a rotor and a stator, and the stator converts changes in the magnetic field generated by the rotation of the rotor into electrical energy. The stator has a stator core and coil ends that are wound around the stator core and protrude from the stator core at both ends. The magnetic field generated when the rotating electric machine is in operation acts on the stator with an electromagnetic force at twice the operating frequency, causing vibration.

[0003] In order to suppress this vibration, it has been proposed to provide an adhesion adjusting member and an insulating member between the stator coils at the coil ends. For example, in Patent Document 1, a tape with a predetermined surface adhesiveness is used as the adhesion adjusting member, and this is interposed between the insulating member filled between the multiple stator coils and the opposing stator coils, thereby adjusting the natural frequency to be lower than the excitation frequency caused by electromagnetic force, thereby preventing resonance caused by electromagnetic force.

[0004] Japanese Patent Application Laid-Open No. 2007-110771

[0005] However, when a rotating electric machine is in operation, the temperature rises due to the effects of Joule heat caused by electromotive force and interlinked magnetic flux, and conventional rotating electric machines have had the problem that the adhesion adjustment members and insulating members between the stator coils hinder cooling.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a rotating electric machine that can suppress temperature rise in the coil ends while suppressing vibrations that occur during operation of the rotating electric machine.

[0007] The stator according to the present disclosure includes a stator core, a stator coil wound around the stator core, and a plurality of support members that are inserted between adjacent stator coils at the coil ends from which the stator coils protrude to hold the stator coils, and have a larger total contact area with the stator coils at the tip ends of the coil ends that are farther from the stator core than at the base ends of the coil ends that are closer to the stator core.

[0008] According to the present disclosure, vibration of the coil end can be suppressed and the amount of cooling air flowing to the root portion of the coil end where the coil temperature is high can be increased, thereby suppressing an increase in the coil temperature at the root portion of the coil end.

[0009] Fig. 3 is a plan view showing a conceptual configuration of a rotary electric machine according to embodiment 1. Fig. 4 is a side view showing an end of a stator of the rotary electric machine according to embodiment 1. Fig. 5 is a view seen from the direction A in Fig. 2 according to embodiment 1. Fig. 6 is a graph showing the relationship between the axial position of a coil end and coil temperature according to embodiment 1. Fig. 7 is a view seen from the direction A in Fig. 2 according to embodiment 2. Fig. 8 is a view seen from the direction A in Fig. 2 according to embodiment 3.

[0010] Embodiment 1. A rotating electric machine according to Embodiment 1 will be described with reference to FIGS. 1, 2, and 3. As shown in FIG. 1, the rotating electric machine 100 includes a stator 300 fixed to a frame 200 and a rotor 400 supported for rotation. The stator 300 converts changes in the magnetic field generated by the rotation of the rotor 400 into electrical energy. FIG. 2 is a side view showing an end of the stator 300 of the rotating electric machine according to Embodiment 1. The stator 300 of the rotating electric machine includes a stator core 1 formed by laminating magnetic plates and a stator coil 2 wound around the stator core 1. The stator coil 2 includes a plurality of upper stator coils 2a and a plurality of lower stator coils 2b. The ends of the upper and lower stator coils 2a, 2b protrude from the end 1a of the stator core 1 and are electrically connected to form a coil end 7. A plurality of insulating rings 3 are inserted between the upper and lower stator coils 2a, 2b to hold the coil end 7 in an annular shape. The outer periphery of the lower stator coil 2 b is supported by a coil end fixing plate 5 .

[0011] The upper and lower stator coils 2a, 2b are adjacent to each other with a gap therebetween, and support members 4 are inserted between adjacent upper stator coils 2a and lower stator coils 2b. The support members 4 maintain a constant gap between adjacent upper stator coils 2a and lower stator coils 2b while ensuring rigidity. The dimensions and shape of the support members 4 are, for example, a rectangular parallelepiped with a thickness of about 1 cm if the gap between adjacent upper stator coils 2a and lower stator coils 2b is about 1 cm, and a contact surface with the upper or lower stator coil 2a, 2b that is a rectangle of about 4 cm square. Here, the dimensions of the contact surface of the support members 4 are the same regardless of the position where they are placed.

[0012] The number of support members 4 and the size of their contact surfaces affect the natural frequency of the coil ends 7. Increasing at least one of the number of support members 4 and the size of their contact surfaces increases the natural frequency of the coil ends 7. In other words, the number of support members 4 and the size of their contact surfaces are determined so that the natural frequency of the coil ends 7 is greater than the excitation frequency caused by electromagnetic force.

[0013] The coil end fixing plate 5, the upper and lower stator coils 2a, 2b, the insulating ring 3, and the support member 4 are fastened together with insulating tape 6, and the coil ends 7 are fixed as a unit.

[0014] The coil ends 7 are cooled from the outside by cooling air 8 that flows through the gaps between the upper and lower stator coils 2 a, 2 b, insulating ring 3, support member 4, and coil end fixing plate 5 from the inner diameter side to the outer diameter side of the stator 300.

[0015] Figure 3 is a view seen from the direction A in Figure 2. A coordinate system is shown in the lower right corner of the figure, with direction C representing the circumferential direction and direction A representing the axial direction. If we consider length L in the axial direction (not along the coil end 7) with end 1a (the coil root) of stator core 1 as the starting point O and tip 7c of coil end 7 as the end point, the side closer to starting point O is coil end root 7a, the side closer to the tip and further from the coil root is coil end tip 7b, and the boundary between coil end root 7a and coil end tip 7b is boundary BD. Support member 4 is not placed at coil end root 7a, but at coil end tip 7b.

[0016] For example, Figure 4 compares the temperature distribution at positions 0 to 1 / 2L, where the coil temperature is particularly high, for a conventional coil end (Figure 4d) and conditions where the boundary BD is changed to 1 / 2L (Figure 4a), 1 / 3L (Figure 4b), and 1 / 4L (Figure 4c). The horizontal axis represents the distance from the starting point O, and the vertical axis represents the internal temperature of the upper stator coil 2a constituting the coil end 7. The coil corner 7d (shown in Figure 3), where the upper and lower stator coils 2a and 2b are curved, experiences high temperatures due to the high magnetic flux density and thick coil insulation caused by the curved shape, making cooling difficult. In other locations, temperatures rise at positions where the support member 4 is located due to the obstruction of cooling airflow. On the other hand, when the boundary BD is changed to 1 / 2L, 1 / 3L, or 1 / 4L (Figures 4a to 4c), although the coil temperature rises slightly at the coil corner 7d, the magnitude of the increase is significantly smaller than that of the conventional coil end (Figure 4d). This is because cooling air flows in a large amount and is cooled in a concentrated manner due to the absence of the support member 4. In particular, when the boundary BD is set to 1 / 2L (FIG. 4a), the coil temperature can be significantly reduced at the coil corner portion 7d, thereby achieving a high cooling effect.

[0017] As mentioned above, heat generated by high magnetic flux density is concentrated particularly at the coil corners 7d. Therefore, the boundary BD should be located at a position between 1 / 4L and 1L from the starting point O, and preferably between 1 / 3L and 1L, so that the coil corners 7d are within an area free of the support member 4. A position of about 1 / 2L can further enhance the cooling effect. The support member 4 is placed in an appropriate position from the perspective of vibration suppression. Specifically, as mentioned above, the position should be determined so that the natural frequency is greater than the excitation frequency due to electromagnetic force.

[0018] By locating the support members 4 at the coil end tips 7b rather than at the coil end roots 7a, ventilation resistance at the coil end roots 7a, where the magnetic flux density is higher and the temperature is more likely to rise than at the coil end tips 7b, is kept low, allowing more cooling air to flow. This prevents the stator coil temperature at the coil end roots 7a from rising. Furthermore, because cooling can be concentrated at the coil end roots 7a, where the temperature is more likely to rise, the axial temperature distribution of the coil ends 7 can be made more uniform.

[0019] Embodiment 2. Figure 5 is a view seen from the direction A in Figure 2. A coordinate system is shown in the lower right of the figure, with direction C representing the circumferential direction and direction A representing the axial direction. In embodiment 1, an example was shown in which no support members 4 were arranged at the coil end root portion 7a, but embodiment 2 shows an example in which fewer support members 4 are arranged at the coil end root portion 7a than at the coil end tip portion 7b. Description of the same configuration as in embodiment 1 will be omitted. In Figure 5, the same reference numerals as in Figure 3 indicate the same or corresponding parts.

[0020] The dimensions and shape of the support member 4 are similar to those of embodiment 1. The support member 4 is a rectangular parallelepiped having a thickness similar to the gap between the adjacent upper and lower stator coils 2 a, 2 b and having contact surfaces with the upper and lower stator coils 2 a, 2 b. The dimensions of the contact surfaces of the support member 4 are the same regardless of the position where the support member 4 is placed.

[0021] In the coil end 7 shown in FIG. 5 , the boundary BD is, for example, 2 / 5L. The number of support members 4 arranged at the coil end root portion 7a is fewer than the number of support members 4 arranged at the coil end tip portion 7b. It is effective to arrange the support members 4 at the coil end root portion 7a in other gaps rather than in the gaps between the upper and lower stator coils 2a and 2b, where the temperature becomes relatively high at each axial position due to differences in circumferential magnetic flux density caused by differences in the phase of the current flowing through the upper and lower stator coils 2a and 2b. For example, in the case of a stator 300 having 72 upper and lower stator coils 2a and 2b, two upper and two lower stator coils 2a and 2b become hot every 60 degrees around the circumference of the coil end 7. For this reason, in the coil end root portion 7a shown in FIG. 5 , support members 4 are not arranged in the three gaps adjacent to the two upper stator coils 2c that become hot. Furthermore, six locations at 60-degree intervals are set where no support members 4 are arranged, thereby reducing the number of support members 4 in the circumferential direction by 18 (one-fourth of the total). The same applies to the support members 4 arranged between the lower stator coils 2b. In other words, the ratio of the number of support members 4 arranged at each axial position of the coil end roots 7a and the coil end tips 7b is 3:4.

[0022] Here, an example has been shown in which the boundary BD is 2 / 5L, but it may be determined in the same manner as in embodiment 1. The ratio of the number of support members 4 arranged at each axial position of the coil end root portion 7a and the coil end tip portion 7b may be, for example, 1:5 to 3:4, with 1:4 being more preferable. The support members 4 are arranged in appropriate positions from the perspective of vibration suppression. Specifically, the positions may be determined so that the natural frequency is greater than the excitation frequency due to electromagnetic force.

[0023] By reducing the number of support members 4 arranged at the coil end root portions 7a compared to the number of support members 4 arranged at the coil end tip portions 7b, ventilation resistance at the coil end root portions 7a is kept low, allowing more cooling air to flow. This prevents the stator coil temperature from rising at the coil end root portions 7a. Furthermore, because cooling can be concentrated on the upper and lower stator coils 2a, 2b, which are prone to temperature rise at the coil end root portions 7a, the axial temperature distribution of the coil ends 7 can be made more uniform.

[0024] Furthermore, by arranging the support members 4 in the coil end roots 7a in spaces other than the gaps between the upper and lower stator coils 2a, 2b, where temperatures tend to be relatively high, it is possible to intensively cool the upper and lower stator coils 2a, 2b, which have higher temperatures. This makes it possible to homogenize not only the axial temperature distribution of the coil ends 7, but also the circumferential temperature distribution of the coil end roots 7a.

[0025] In the first and second embodiments, examples have been shown in which all of the support members 4 have the same size and shape, but some of them may have different shapes and sizes.

[0026] Embodiment 3. Figure 6 is a view seen from the direction of the arrow A in Figure 2. A coordinate system is shown in the lower right of the figure, with direction C representing the circumferential direction and direction A representing the axial direction. In embodiments 1 and 2, examples were shown in which the number of support members 4 arranged on the coil end 7 was changed, but in embodiment 3, an example is shown in which the contact surface dimensions of the support members 4 are changed. Descriptions of configurations similar to those in embodiments 1 and 2 will be omitted. The same reference numerals in Figure 6 as in Figure 3 indicate the same or corresponding parts.

[0027] Of the support members 4, the support member 4a arranged in part of the coil end root portion 7a has a smaller contact surface dimension than the other support members 4b. For example, the radial length of the contact surface dimension of the support member 4a is 4 cm and the axial length is 2 cm. The contact surface dimension of the support member 4b is the same as that of the support member 4 in embodiment 1. Because the support members 4a and 4b maintain a constant gap between the adjacent upper or lower stator coils 2a, 2b, their thicknesses are the same as those in embodiments 1 and 2.

[0028] In the coil end 7 shown in FIG. 6 , the boundary BD is, for example, 4 / 9L. The contact surface dimensions of the support member 4a disposed in a portion of the coil end root portion 7a are smaller than those of the support member 4 shown in the first and second embodiments. It is effective to position the support member 4a between the upper and lower stator coils 2a and 2b, for example, where the temperature becomes relatively high at each axial position due to differences in circumferential magnetic flux density caused by differences in the phase of the currents flowing through the upper and lower stator coils 2a and 2b. As described in the second embodiment, for example, in the case of a stator 300 having 72 upper and lower stator coils 2a and 2b, two upper and two lower stator coils 2a and 2b reach high temperatures every 60 degrees around the circumference of the coil end 7. For this reason, in the coil end root portion 7a shown in FIG. 6 , support members 4a with small contact surface dimensions are disposed in three gaps adjacent to the two upper stator coils 2c that reach high temperatures. Furthermore, since the support members 4a are arranged at six locations every 60 degrees, 18 support members 4a are arranged in the circumferential direction. The same applies to the support members 4a arranged between the lower stator coils 2b.

[0029] Here, an example is shown in which the boundary BD is set to 4 / 9L, but this may be determined in the same manner as in embodiment 1. For example, the ratio of the contact surface dimensions of the support member 4 at the coil end root portion 7a and the coil end tip portion 7b may be set to 1:4 to 2:3, and preferably 1:2. The support members 4a, 4b are positioned so as to have appropriate positions and dimensions from the perspective of vibration suppression. Specifically, the position and contact surface dimensions may be determined so that the natural frequency is greater than the excitation frequency due to electromagnetic force.

[0030] In this way, by making the contact surface dimension between at least one of the support members 4 arranged at the coil end root portion 7a and the stator coil 2 smaller than the contact surface dimension between the support member 4 arranged at the coil end tip portion 7b and the stator coil 2, the ventilation resistance at the coil end root portion 7a is kept low and more cooling air flows. This makes it possible to suppress a rise in the temperature of the stator coil at the coil end root portion 7a. Furthermore, because it is possible to cool intensively the upper and lower stator coils 2a, 2b, which are prone to temperature rise at the coil end root portion 7a, the axial temperature distribution of the coil end 7 can be made more uniform.

[0031] Furthermore, at the coil end root portions 7a, the support members 4a, which have smaller contact surface dimensions than the support members 4 in the first and second embodiments, are arranged between the upper and lower stator coils 2a, 2b, the areas around which the temperatures become relatively higher, and therefore the upper and lower stator coils 2a, 2b, which have higher temperatures, can be cooled intensively. This makes it possible to uniform not only the axial temperature distribution of the coil ends 7, but also the circumferential temperature distribution of the coil end root portions 7a.

[0032] In this embodiment, an example has been shown in which support members 4a with smaller contact surface dimensions than support member 4 are arranged in part of coil end root portion 7a, but they may also be arranged in coil end tip portion 7b. Also, in embodiment 3, all of the support members arranged in coil end root portion 7a may be support members 4a with smaller contact surface dimensions than support member 4.

[0033] In addition to the above, the embodiments can be freely combined, any of the components of the embodiments can be modified, or any of the components of the embodiments can be omitted.

[0034] 100 Rotating electric machine, 200 Frame, 300 Stator, 400 Rotor, 1 Stator core, 2 Stator coil, 2a Upper stator coil, 2b Lower stator coil, 3 Insulating ring, 4, 4a, 4b Support member, 5 Coil end fixing plate, 6 Insulating tape, 7 Coil end, 7a Coil end root portion, 7b Coil end tip portion, 8 Cooling air

Claims

1. A stator core, a stator coil wound around the stator core, at the coil ends where the stator coil protrudes, a plurality of support members inserted between adjacent stator coils to hold the stator coils, and having a larger total contact area with the stator coils at the coil end tip portions farther from the stator core than at the coil end root portions closer to the stator core, a stator comprising the same.

2. The plurality of support members are not arranged at the coil end root portions and are arranged at the coil end tip portions, the stator according to Claim 1.

3. The number of the support members arranged at the coil end root portions is less than the number of the support members arranged at the coil end tip portions, the stator according to Claim 1.

4. The contact surface dimensions of at least any one of the support members arranged at the coil end root portions with the stator coil are smaller than the contact surface dimensions of the support members arranged at the coil end tip portions with the stator coil, the stator according to Claim 1.

5. The boundary between the coil end root portion and the coil end tip portion is at a position of not less than 1 / 4L and less than 1L in the axial direction with the length from the end of the stator core as the starting point and the tip of the coil end as the ending point being L, the stator according to any one of Claims 1 to 4.

6. A rotor, the stator according to any one of Claims 1 to 4 arranged around the rotor, a rotating electrical machine comprising the same.

7. A rotor, the stator according to Claim 5 arranged around the rotor, a rotating electrical machine comprising the same.