Rotary electric machine

Abstract

To provide a rotary electric machine in which a cooling structure of a coil is simple and torque can be improved while suppressing a temperature rise bias in the coil.SOLUTION: A rotary electric machine includes an annular rotor 2 fixed to a rotation shaft 1 extending in a substantially horizontal direction, a stator core 3 in which slots 33 are formed between teeth 32 extending radially inward from a substantially annular yoke 31, and a coil 4 wound around the teeth 32. A cooling liquid is applied to the upper side of a coil end portion 41, and thereby the coil 4 is cooled. The quantity of heat generated when current flows through the coil 4 is varied for each of a plurality of portions split in the circumferential direction so that a temperature rise bias in the coil 4 is reduced. The area of a cross section of the slot 33, the number of conductive wires of the coil 4 passing through the slot 33 in the axial direction, or a current flowing through the coil 4 is varied for each of the plurality of portions split in the circumferential direction so that the torque is improved.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine including a stator core having a plurality of teeth extending radially inward from the inner peripheral surface of a substantially annular yoke, and coils wound around the teeth. [Background technology]

[0002] Patent Document 1 discloses a rotating electric machine including a ring-shaped rotor fixed to a rotating shaft extending in a substantially horizontal direction, a stator core disposed radially outward of the rotor, and coils having coil end portions protruding axially outward from the stator core. The rotating electric machine disclosed in Patent Document 1 includes a cooler provided with multiple injection holes that inject coolant toward the axial end faces or outer peripheral surfaces of the coil end portions to cool the coils, which generate heat when current is applied. In this rotating electric machine, the injection holes provided at the top and bottom of the coils have different opening areas to prevent uneven temperatures between the top and bottom of the coils.

[0003] Patent Document 2 discloses a generator in which the heat dissipation effect of the stator coil varies depending on the location due to external factors. In the generator disclosed in Patent Document 2, in order to suppress uneven temperature rise of the coil, the cross-sectional area of ​​the coil conductor wire in the part with small heat dissipation effect is made larger than the cross-sectional area of ​​the coil conductor wire in the part with large heat dissipation effect. Because the Joule heat that generates heat in the coil is proportional to the electrical resistance of the coil, by increasing the cross-sectional area of ​​the coil conductor wire in the part with small heat dissipation effect, the temperature of the coil in the part with small heat dissipation effect can be lowered. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-108361 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-081934 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Document 1, a rotating electric machine is known that includes a ring-shaped rotor fixed to a rotating shaft extending substantially horizontally, a stator core disposed radially outward of the rotor, and coils having coil end portions that protrude axially outward from the stator core. In such a rotating electric machine, when a coolant is poured onto the coil end portions from above, the coolant flows from an upper portion P1 of the coil end portions, along both the left and right sides of the coil end portions, to a lower portion P5, and then flows downward from the lower portion P5 of the coil end portions, as shown by the dashed arrows in Figure 8.

[0006] When cooling the coil by applying coolant to the upper side of the coil end portion in this manner, the coolant gradually removes heat from the coil as it flows from the upper part P1 of the coil end portion along both sides of the coil end portion to the lower part P5. As a result, the temperature of the coolant flowing down from the lower part P5 of the coil end portion at the end of application is higher than the temperature of the coolant flowing down from the upper part of the coil end portion at the beginning of application. For example, assume that the temperature of the coolant flowing down from the lower part P5 of the coil end portion at the end of application is 60°C and that the temperature of the coolant flowing down from the lower part of the coil end portion at the end of application is 100°C. To simplify the calculation of the coil temperature, assume that the coil is divided circumferentially into eight equal parts as shown in Figure 8, and that the coolant temperatures in each part are as shown in Figure 9. The eight parts are the upper part P1, upper right part P2, right part P3, lower right part P4, lower part P5, lower left part P6, left part P7, and upper left part P8, which are divided by the dashed dotted lines shown in Figure 8.

[0007] Figure 10 is a graph showing the results of a thermal analysis simulation of the relationship between the coolant temperature and the coil temperature. Assuming the coolant temperatures in the eight parts as described above, the relationship between the coolant temperature and the coil temperature shown in Figure 10 indicates that the coil temperature in each part will be the temperature shown in Figure 9. In other words, when the coil is cooled by pouring coolant onto the upper part P1 of the coil end, the temperature rise of the coil will be uneven, with the temperature at the lower part P5 being the highest.

[0008] In rotating electric machines, as the temperature of the coil rises, the heat resistance and voltage resistance of the coating on the coil surface deteriorate, potentially resulting in dielectric breakdown. To prevent such dielectric breakdown, the design of the rotating electric machine requires that the temperature of the hottest part of the coil be kept below a certain level. Therefore, if there is a bias in the temperature rise of the coil, as shown in Figure 9, the maximum temperature of the lower part P5 will determine the rate at which current above a certain value can flow through the coil. Since the current that can flow through the coil is limited to a certain value, the torque of the rotating electric machine is also limited to a certain value.

[0009] One possible method for suppressing this uneven temperature rise in the coil is to provide a cooler with multiple injection holes that inject coolant into the coil end portion, as in the rotating electric machine disclosed in Patent Document 1, and increase the opening area of ​​the injection holes that inject coolant into the portion of the coil that generates the most heat. This method allows for concentrated cooling of the portion of the coil that generates the most heat, thereby increasing the amount of current that can be passed through the coil. However, a rotating electric machine equipped with such a cooler with multiple injection holes has a more complex coil cooling structure than a rotating electric machine that sprays coolant only on the upper portion P1 of the coil end portion, resulting in increased costs. Furthermore, a rotating electric machine equipped with such a cooler requires an increased flow rate of coolant delivered from the pump in accordance with the increased opening area of ​​the injection holes, which raises concerns about increased pumping losses.

[0010] Another possible method for suppressing uneven coil temperature rise is to suppress heat generation by expanding the cross-sectional area of ​​the coil in the portion where the temperature becomes high, as in the generator disclosed in Patent Document 2. However, while Patent Document 2 describes partially expanding the cross-sectional area of ​​the coil, it does not describe changing the shape of the stator core, making it unclear whether this method also involves changing the shape of the stator core. In rotating electrical machines using stator cores in which teeth extend radially inward from the inner peripheral surface of a substantially annular yoke and slots are formed between the teeth, coils are generally filled in the slots. Therefore, expanding the cross-sectional area of ​​the coils requires increasing the cross-sectional area of ​​the slots as well. Furthermore, increasing the cross-sectional area of ​​the slots reduces the circumferential width of the teeth and the radial width of the yoke, thereby reducing the torque of the rotating electrical machine.

[0011] FIG. 11 is a graph showing the results of a simulation performed using electromagnetic field analysis on the relationship between the cross-sectional area of ​​the slot and the torque of the rotating electric machine, with the ratio of the circumferential width of the tooth to the radial width of the yoke fixed. In the graph shown in FIG. 11, the reference value of the cross-sectional area of ​​the slot is plotted as 100% on the horizontal axis, and the torque value corresponding to the reference value of the cross-sectional area of ​​the slot is plotted as 100% on the vertical axis. FIG. 12 is a graph showing the results of a simulation performed using thermal analysis on the relationship between the heat generation amount and temperature of the coil. In the graph shown in FIG. 12, the heat generation amount at which the coil temperature reaches 208°C is plotted as 100% on the horizontal axis. To reduce the temperature of the lower coil part P5 from 208°C by approximately 10°C, the heat generation amount must be reduced to 90%, based on the relationship between the heat generation amount and temperature of the coil shown in FIG. 12. The Joule heat of the coil is proportional to the electrical resistance, assuming a constant current value. Therefore, to reduce the heat generation amount to 90%, the cross-sectional areas of the coil and slot must be increased by approximately 1.1 times. If the cross-sectional area of ​​the slot is increased by 1.1 times, the torque of the rotating electrical machine will decrease by about 3% due to the relationship between the cross-sectional area of ​​the slot and the torque of the rotating electrical machine shown in FIG.

[0012] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating electric machine that has a simple coil cooling structure and that can improve torque while suppressing uneven temperature rise of the coil. [Means for solving the problem]

[0013] The rotating electric machine of the present invention comprises: a circular rotor fixed to a rotating shaft extending in an approximately horizontal direction and rotating integrally with the rotating shaft; a stator core arranged radially outside the rotor and having an approximately circular yoke and a plurality of teeth extending radially inward from the inner surface of the yoke, with slots formed between circumferentially adjacent teeth; and coils wound around the teeth, wherein the coils have coil end portions that protrude axially from the axial end face of the stator core, and the coils are cooled by pouring coolant over the coil end portions.The rotating electric machine is characterized in that by varying the amount of heat generated by passing current through the coil for each of a plurality of circumferentially divided parts, the uneven temperature rise of the coil is reduced, and by varying the cross-sectional area of ​​the slot cut by a plane perpendicular to the axial direction, the number of wires of the coil that pass axially through the slot, or the current flowing through the coil for each of the plurality of parts, the torque is improved.

[0014] In one aspect of the rotating electric machine of the present invention, the cross-sectional area of ​​the coil wire may differ for each of the multiple parts, and the cross-sectional area of ​​the coil wire may become smaller as it moves upward from the bottom to the top, and the cross-sectional area of ​​the slot cut by a plane perpendicular to the axial direction may differ for each of the multiple parts, and the cross-sectional area of ​​the slot may become smaller as it moves upward from the bottom to the top.

[0015] In one aspect of the rotating electric machine of the present invention, the number of wires of the coil that pass through the slot in the axial direction may differ for each of the multiple parts, and the number of wires of the coil that pass through the slot in the axial direction may increase as you move upward from the bottom to the top.

[0016] In one aspect of the rotating electric machine according to the present invention, a current flowing through the coil may be different for each of the plurality of portions, and the current flowing through the coil may increase upward from the bottom to the top.

[0017] In one aspect of the rotating electric machine of the present invention, a temperature sensor may be provided to measure the temperature of the coil for each of the plurality of parts, and the current flowing through the coil for each of the plurality of parts may be changed depending on the temperature of the coil for each of the plurality of parts measured by the temperature sensor.

[0018] According to this aspect, even when the flow rate of the coolant changes or when the rotating electrical machine tilts during operation, the heat generation amount of the coil can be adjusted for each of the multiple portions divided in the circumferential direction.

[0019] In one aspect of the rotating electric machine of the present invention, a calculation device is provided that can calculate the temperature of the coil for each of the multiple parts from the operating conditions of the rotating electric machine, and the current flowing through the coil for each of the multiple parts may be changed depending on the temperature of the coil for each of the multiple parts calculated by the calculation device.

[0020] According to this aspect, even when the flow rate of the coolant changes or when the rotating electrical machine tilts during operation, the heat generation amount of the coil can be adjusted for each of the multiple portions divided in the circumferential direction. [Effects of the Invention]

[0021] The present invention can provide a rotating electric machine that has a simple coil cooling structure and can improve torque while suppressing uneven temperature rise of the coil. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view of a rotating electric machine according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing a cross section of a stator core and a coil passing through a slot. [Figure 3] 3 is a diagram showing a cross section of a conductor wire of a coil and slots in the upper part of the rotating electric machine of the first embodiment. FIG. [Figure 4] 3 is a diagram showing a cross section of a conductor wire of a coil and slots in a lower part of the rotating electric machine of the first embodiment. FIG. [Figure 5]10 is a diagram showing a cross section of a conductor wire of a coil and slots in an upper part of a rotating electric machine according to a second embodiment. FIG. [Figure 6] 10 is a diagram showing a cross section of a conductor wire of a coil and slots in a lower part of a rotating electric machine according to a second embodiment. FIG. [Figure 7] 10 is a diagram showing a cross section of a stator core of a rotary electric machine according to a third embodiment and a coil passing through a slot. FIG. [Figure 8] FIG. 10 is a diagram showing the flow of coolant that has fallen onto the upper part of the coil end portion. [Figure 9] FIG. 10 is a diagram showing the temperatures of the coolant and the coil in eight parts P1 to P8. [Figure 10] 10 is a graph showing the results of a thermal analysis simulation of the relationship between the temperature of the coolant and the temperature of the coil. [Figure 11] 10 is a graph showing the results of simulating the relationship between the cross-sectional area of ​​a slot and the torque of a rotating electric machine by electromagnetic field analysis. [Figure 12] 10 is a graph showing the results of a thermal analysis simulation of the relationship between the heat generation amount and temperature of a coil. DETAILED DESCRIPTION OF THE INVENTION

[0023] First Embodiment A rotating electric machine 10 according to a first embodiment will be described below with reference to Figures 1 to 4. Figure 1 is a perspective view of the rotating electric machine 10. As shown in Figure 1, the rotating electric machine 10 includes an annular rotor 2 fixed to a rotating shaft 1 extending substantially horizontally and rotating integrally with the rotating shaft 1, a stator core 3 disposed radially outward of the rotor 2, and coils 4. The rotor 2 includes a plurality of permanent magnets 21.

[0024] 2 is a diagram showing a cross section of the stator core 3 and the coil 4 passing through the slot 33. As shown in FIG. 2, the stator core 3 has a substantially annular yoke 31 and 48 teeth 32 extending radially inward from the inner peripheral surface of the yoke 31. Slots 33 are formed between adjacent teeth 32 in the circumferential direction, penetrating in the axial direction of the rotating shaft 1. The coil 4 is wound around the teeth 32, and has coil end portions 41 that protrude in the axial direction of the rotating shaft 1 from the axial end face of the stator core 3, as shown in FIG.

[0025] In the rotating electric machine 10, coolant sent from an oil pump (not shown) is applied from above the outer peripheral surface of the coil end portion 41, as shown by arrow A1 in FIG. 1. The coolant flows from the top of the coil end portion 41, down both left and right sides of the coil end portion 41, to the bottom, and then flows downward from the bottom of the coil end portion 41. The coolant that flows downward from the bottom of the coil end portion 41 is then returned to the oil pump through a recovery path (not shown). In this way, in the rotating electric machine 10, the coolant removes heat from the coil 4 as it flows from the top of the coil end portion 41, down both left and right sides of the coil end portion 41, to the bottom, thereby cooling the coil 4.

[0026] The coil 4 is formed by sequentially connecting multiple segment coils, each bent into a roughly U-shape so that the two legs extend parallel to each other. During the coil 4 formation process, the legs of the segment coils are inserted into the slots 33 from one axial end of the stator core 3, with the tips of the legs protruding from the other axial end of the stator core 3. Then, with the tips of the legs of the segment coils protruding from the other axial end of the stator core 3, the tips of the legs of the segment coils are connected to the tips of the legs of other segment coils, thereby connecting the segment coils to form the coil 4. Because the rotating electric machine 10 forms the coil 4 by connecting multiple segment coils in this manner, the cross-sectional area of ​​the coil 4 can be varied for each of the eight parts, as described below. All of the segment coils are made of rectangular wire with a rectangular cross section.

[0027] In the rotating electric machine 10, the cross-sectional areas of the conductors 42 of the coil 4 and the slots 33 vary for each of eight parts equally divided in the circumferential direction. The eight parts are an upper part P1, an upper right part P2, a right part P3, a lower right part P4, a lower part P5, a lower left part P6, a left part P7, and an upper left part P8, which are divided by the dashed lines shown in FIG. 2 . The uppermost part of these eight parts is the upper part P1, and the lowermost part is the lower part P5. Each of these eight parts includes six slots 33. FIG. 3 is a diagram showing a cross section of the conductors 42 of the coil 4 and the slots 33 in the upper part P1 of the rotating electric machine 10. FIG. 4 is a diagram showing a cross section of the conductors 42 of the coil 4 and the slots 33 in the lower part P5 of the rotating electric machine 10. In the rotating electric machine 10, the same number of conductors 42 of the coil 4 are inserted into each slot 33. FIGS. 3 and 4 show a cross section of the coil 4 when four conductors 42 of the coil 4 are inserted into each slot 33.

[0028] 3 and 4, the cross-sectional area of ​​the conductor 42 of the coil 4 in the upper portion P1 is smaller than the cross-sectional area of ​​the conductor 42 of the coil 4 in the lower portion P5. The cross-sectional area of ​​the conductor 42 of the coil 4 varies for each of the eight portions, and the cross-sectional area of ​​the conductor 42 decreases upward from the lower portion P5 to the upper portion P1. That is, the cross-sectional area of ​​the conductor 42 in the lower portion P5 is the largest, the cross-sectional area of ​​the conductor 42 in the lower right portion P4 and the lower left portion P6 is smaller than the cross-sectional area of ​​the conductor 42 in the lower portion P5, the cross-sectional area of ​​the conductor 42 in the right portion P3 and the left portion P7 is smaller than the cross-sectional area of ​​the conductor 42 in the lower right portion P4 and the lower left portion P6, the cross-sectional area of ​​the conductor 42 in the upper right portion P2 and the upper left portion P8 is smaller than the cross-sectional area of ​​the conductor 42 in the right portion P3 and the left portion P7, and the cross-sectional area of ​​the conductor 42 in the upper portion P1 is smaller than the cross-sectional area of ​​the conductor 42 in the upper right portion P2 and the upper left portion P8. The cross-sectional area of ​​the conductor 42 in the lower right portion P4 is the same as the cross-sectional area of ​​the conductor 42 in the lower left portion P6, the cross-sectional area of ​​the conductor 42 in the right portion P3 is the same as the cross-sectional area of ​​the conductor 42 in the left portion P7, and the cross-sectional area of ​​the conductor 42 in the upper right portion P2 is the same as the cross-sectional area of ​​the conductor 42 in the upper left portion P8.

[0029] The cross-sectional area of ​​each slot 33 taken along a plane perpendicular to the direction of the rotation axis 1 is large enough to accommodate four conductive wires 42. Therefore, the cross-sectional area of ​​the slot 33 varies among the eight parts, and decreases upward from the lower part P5 to the upper part P1. That is, the cross-sectional area of ​​the slot 33 in the lower part P5 is largest, the cross-sectional areas of the slots 33 in the lower right part P4 and the lower left part P6 are smaller than the cross-sectional area of ​​the slot 33 in the lower part P5, the cross-sectional areas of the slots 33 in the right part P3 and the left part P7 are smaller than the cross-sectional areas of the slots 33 in the lower right part P4 and the lower left part P6, the cross-sectional area of ​​the slots 33 in the upper right part P2 and the upper left part P8 is smaller than the cross-sectional area of ​​the slots 33 in the right part P3 and the left part P7, and the cross-sectional area of ​​the slot 33 in the upper part P1 is smaller than the cross-sectional area of ​​the slots 33 in the upper right part P2 and the upper left part P8. The cross-sectional area of ​​the slot 33 in the lower right portion P4 is the same as the cross-sectional area of ​​the slot 33 in the lower left portion P6, the cross-sectional area of ​​the slot 33 in the right portion P3 is the same as the cross-sectional area of ​​the slot 33 in the left portion P7, and the cross-sectional area of ​​the slot 33 in the upper right portion P2 is the same as the cross-sectional area of ​​the slot 33 in the upper left portion P8.

[0030] In order to vary the cross-sectional area of ​​the slots 33 for each of the eight parts, at least one of the circumferential width of the teeth 32 and the radial width of the yoke 31 varies for each of the eight parts. Figures 3 and 4 show a cross section of the conductor 42 and the stator core 3 when both the circumferential width of the teeth 32 and the radial width of the yoke 31 vary for each of the eight parts. As shown in Figures 3 and 4, when both the circumferential width of the teeth 32 and the radial width of the yoke 31 vary for each of the eight parts, the circumferential width of the teeth 32 and the radial width of the yoke 31 are smallest at the lower part P5 and increase upward from the lower part P5 to the upper part P1.

[0031] The smaller the cross-sectional area of ​​the conductor 42, the higher the electrical resistivity of the coil 4, and therefore the amount of heat generated. Therefore, in the rotating electric machine 10, the cross-sectional area of ​​the conductor 42 of the coil 4 varies for each of the eight parts as described above, so that the temperature of the entire coil 4 is made uniform and uneven temperature rise in the coil 4 can be suppressed compared to when the conductor 42 of all eight parts has the same cross-sectional area as the conductor 42 in the lower part P5.

[0032] Furthermore, in the rotating electric machine 10, because the cross-sectional area of ​​the slots 33 differs for each of the eight parts as described above, torque can be improved compared to a case in which all of the slots 33 have the same cross-sectional area as the slots 33 in the lower part P5. When thermal analysis and electromagnetic field analysis were performed on the rotating electric machine 10 in which the cross-sectional areas of the conductors 42 of the coils 4 and the slots 33 differ for each of the eight parts as described above, the results showed that torque was improved by 3.8% compared to a rotating electric machine in which the cross-sectional areas of the conductors 42 and the slots 33 in all eight parts are the same as in the lower part P5.

[0033] In this way, the rotating electric machine 10 can improve torque while suppressing uneven temperature rise in the coil 4. In order to minimize uneven temperature rise in the coil 4, the rotating electric machine 10 needs to determine the cross-sectional areas of the wires 42 and the slots 33 in the eight parts P1 to P8 after confirming the temperature distribution of the coil 4 through thermal analysis simulations and experiments. In the rotating electric machine 10 described above, the cross-sectional areas of the wires 42 and the slots 33 are different for each of the eight parts obtained by dividing the circumferential direction into eight equal parts, but the number of parts divided circumferentially does not have to be eight. For example, the cross-sectional areas of the wires 42 and the slots 33 may be different for each of the 16 parts obtained by dividing the circumferential direction into 16 equal parts, or the cross-sectional areas of the wires 42 and the slots 33 may be different for each of the 16 slots 33.

[0034] <Second embodiment> Next, a rotating electric machine 20 according to a second embodiment will be described with reference to Figures 5 and 6. The rotating electric machine 20 according to the second embodiment has the same configuration as the rotating electric machine 10 according to the first embodiment, except that the cross-sectional areas of the slots 33a are all the same and the number of conductors 42a of the coils 4a passing through the slots 33a varies for each of the multiple circumferentially divided portions. Therefore, the same components as those in the rotating electric machine 10 according to the first embodiment are denoted by the same reference numerals and will not be described.

[0035] The rotating electric machine 20 comprises a ring-shaped rotor 2 fixed to a rotating shaft 1 extending substantially horizontally and rotating integrally with the rotating shaft 1, a stator core 3a arranged radially outside the rotor 2, and a coil 4a.

[0036] The stator core 3a has a substantially annular yoke 31a and 48 teeth 32a extending radially inward from the inner circumferential surface of the yoke 31a. Slots 33a penetrating in the axial direction of the rotating shaft 1 are formed between adjacent teeth 32a in the circumferential direction. The radial width of the yoke 31a is uniform around the entire circumference, and all teeth 32a have the same radial length and circumferential width. Therefore, the cross-sectional area of ​​the slots 33a when cut along a plane perpendicular to the direction of the rotating shaft 1 is the same.

[0037] The coil 4a is wound around the teeth 32a, and like the coil 4 of the rotating electric machine 10 of the first embodiment, has a coil end portion 41 that protrudes from the axial end face of the stator core 3a in the axial direction of the rotating shaft 1. Like the rotating electric machine 10 of the first embodiment, the rotating electric machine 20 also has a coolant sprayed from above the outer circumferential surface of the coil end portion 41.

[0038] In the rotating electric machine 20, the number of conductors 42a of the coil 4a that pass through the slots 33a in the axial direction differs between the upper and lower portions that are divided circumferentially. FIG. 5 is a diagram showing a cross section of the conductors 42a of the coil 4a in the upper portion and the slots 33a. As shown in FIG. 5, five conductors 42a pass through in the axial direction in the upper portion. FIG. 6 is a diagram showing a cross section of the conductors 42a of the coil 4a in the lower portion and the slots 33a. As shown in FIG. 6, four conductors 42a pass through in the axial direction in the lower portion. Although the cross-sectional area of ​​the slot 33a is the same in the upper and lower portions, the upper portion has more conductors 42a passing through it, so the cross-sectional area per conductor 42a is smaller in the upper portion than in the lower portion.

[0039] As described above, in the rotating electric machine 20, the number of wires 42a passing through the slots 33a is greater in the upper part than in the lower part, and the cross-sectional area of ​​the wires 42a is smaller, resulting in a higher electrical resistance. Therefore, in the rotating electric machine 20, the temperature of the entire coil 4a is more uniform, and uneven temperature rise of the coil 4a can be suppressed, compared to when four wires 42a pass through the slots 33a in the axial direction in both the upper and lower parts.

[0040] Furthermore, since the rotating electric machine 20 has five conductors 42a passing through the upper slots 33a, the magnetomotive force at the upper part is increased compared to when there are four conductors 42a passing through the slots 33a axially at both the upper and lower parts, thereby improving torque.

[0041] <Third embodiment> Next, a rotating electric machine 30 according to a third embodiment will be described with reference to Fig. 7. The rotating electric machine 30 according to the third embodiment has the same configuration as the rotating electric machine 10 according to the first embodiment, except that the cross-sectional areas of the conductors of the coils 4b and the slots 33a are all the same, and the current value of the coils 4b differs for each of the multiple circumferentially divided portions. Therefore, the same components as those in the rotating electric machine 10 according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0042] The rotating electric machine 30 includes a ring-shaped rotor 2 fixed to a rotating shaft 1 extending substantially horizontally and rotating integrally with the rotating shaft 1, a stator core 3a arranged radially outside the rotor 2, and a coil 4b.

[0043] The stator core 3a has a substantially annular yoke 31a and 48 teeth 32a extending radially inward from the inner circumferential surface of the yoke 31a. Slots 33a penetrating in the axial direction of the rotating shaft 1 are formed between adjacent teeth 32a in the circumferential direction. The radial width of the yoke 31a is uniform around the entire circumference, and all teeth 32a have the same radial length and circumferential width. Therefore, the cross-sectional area of ​​the slots 33a when cut along a plane perpendicular to the direction of the rotating shaft 1 is the same.

[0044] The coils 4b are wound around the teeth 32a, and like the coils 4 of the rotating electric machine 10 of the first embodiment, have coil end portions 41 that protrude in the axial direction of the rotating shaft 1 from the axial end face of the stator core 3a. Like the rotating electric machine 10 of the first embodiment, the rotating electric machine 30 also has a coolant applied from above the outer peripheral surface of the coil end portions 41. The conductors of the coils 4b all have the same cross-sectional area.

[0045] FIG. 7 is a cross-sectional view of the stator core 3a of the rotating electric machine 30 and the coils 4b passing through the slots 33a. In the rotating electric machine 30, a first inverter (not shown) is connected to the coils 4b axially passing through the slots 33a above the dashed-dotted line L1 shown in FIG. 7, and a second inverter (not shown) is connected to the coils 4b axially passing through the slots 33a below the dashed-dotted line L1. That is, the first inverter is connected to the upper half of the coils 4b, and the second inverter is connected to the lower half of the coils 4b. The current flowing through the upper half of the coils 4b is larger than the current flowing through the lower half of the coils 4b. Therefore, in the rotating electric machine 30, the temperature of the entire coils 4b is more uniform, thereby suppressing uneven temperature rise in the coils 4b, compared to when the current flowing through the upper half of the coils 4b is the same as the current flowing through the lower half of the coils 4b.

[0046] Furthermore, in the rotating electric machine 30, the current flowing through the upper half of the coil 4b is greater than the current flowing through the lower half of the coil 4b, and therefore the magnetomotive force in the upper half of the coil 4b is increased compared to when the current flowing through the upper half of the coil 4b is the same magnitude as the current flowing through the lower half of the coil 4b, thereby improving the torque.

[0047] The rotating electric machine 30 can determine the values ​​of the currents to be passed through the upper and lower halves of the coil 4b by checking the temperature distribution of the coil 4b according to the operating conditions through thermal analysis simulations or experiments. Alternatively, the rotating electric machine 30 may be provided with temperature sensors on the upper and lower parts of the coil 4b to measure the temperatures of the upper and lower parts of the coil 4b in real time and determine the values ​​of the currents to be passed through the upper and lower halves of the coil 4b according to the temperatures measured by the temperature sensors. Instead of providing a temperature sensor, the rotating electric machine 30 may be provided with a computing device that can calculate the temperature distribution of the coil 4b according to the operating conditions and determine the values ​​of the currents to be passed through the upper and lower halves of the coil 4b according to the temperature calculated by the computing device. By providing a temperature sensor or computing device in this way, the rotating electric machine 30 can grasp the temperature of the coil 4b in real time and perform optimal current control to suppress uneven temperature increases in the coil 4b, even when the flow rate of the coolant changes or the rotating electric machine 30 tilts during operation.

[0048] In the rotating electric machine 30 described above, the coil 4b is divided into two, an upper part and an upper part, but the number of divisions may be other than two. For example, the coil 4b may be divided into eight parts as in the rotating electric machine 10 of the first embodiment, with an inverter connected to each of the eight parts, from the upper part P1 to the upper left part P8, and the current flowing through the coil 4b may increase upward from the lower part P5 to the upper part P1. Also, an H-bridge current controller may be connected to each turn of the coil 4b, so that the current value varies for each turn. Increasing the number of divisions of the coil 4b in this way can further improve the effect of suppressing uneven temperature rise in the coil 4b.

[0049] <Supplementary information on the embodiment> The rotating electric machine of the present invention is not limited to the above-described embodiment, and can be embodied in various forms within the scope of the present invention. For example, the number of teeth of the stator core may be any number other than 48. [Explanation of symbols]

[0050] 1 rotating shaft, 2 rotor, 3, 3a stator core, 4, 4a, 4b coil, 10, 20, 30 rotating electric machine, 21 permanent magnet, 31, 31a yoke, 32, 32a teeth, 33, 33a slot, 41 coil end portion, 42, 42a conductor, P1 upper portion, P2 upper right portion, P3 right portion, P4 lower right portion, P5 lower portion, P6 lower left portion, P7 left portion, P8 upper left portion.

Claims

1. a rotor having an annular shape fixed to a rotation shaft extending in a substantially horizontal direction and rotating integrally with the rotation shaft; a stator core disposed radially outward of the rotor, the stator core having a substantially annular yoke and a plurality of teeth extending radially inward from an inner circumferential surface of the yoke, with slots formed between adjacent teeth in the circumferential direction; a coil wound around the tooth, The coil has a coil end portion that protrudes in the axial direction from an axial end surface of the stator core, A rotating electric machine in which a coolant is poured onto an upper side of the coil end portion to cool the coil, By varying the amount of heat generated by energizing the coil for each of the multiple circumferentially divided portions, the uneven temperature rise of the coil is reduced, A rotating electric machine characterized in that torque is improved by varying the cross-sectional area of ​​the slot cut by a plane perpendicular to the axial direction, the number of wires of the coil passing through the slot in the axial direction, or the current flowing through the coil for each of the multiple portions.

2. 2. The rotating electric machine according to claim 1, The cross-sectional area of ​​the conductor wire of the coil varies for each of the plurality of portions, and the cross-sectional area of ​​the conductor wire of the coil becomes smaller as it goes upward from the bottom to the top, A rotating electric machine characterized in that the cross-sectional area of ​​the slot when cut by a plane perpendicular to the axial direction varies for each of the multiple portions, and the cross-sectional area of ​​the slot becomes smaller as it moves upward from the bottom to the top.

3. 2. The rotating electric machine according to claim 1, A rotating electric machine characterized in that the number of wires of the coil passing through the slots in the axial direction varies for each of the multiple sections, and the number of wires of the coil passing through the slots in the axial direction increases as you move upward from the bottom to the top.

4. 2. The rotating electric machine according to claim 1, A rotating electric machine characterized in that the current flowing through the coil varies for each of the plurality of portions, and the current flowing through the coil increases as it goes upward from the bottom to the top.

5. 5. The rotating electric machine according to claim 4, A rotating electric machine characterized by having a temperature sensor that measures the temperature of the coil for each of the multiple parts, and changing the current flowing through the coil for each of the multiple parts depending on the temperature of the coil for each of the multiple parts measured by the temperature sensor.

6. 5. The rotating electric machine according to claim 4, A rotating electric machine characterized by comprising an arithmetic device that can calculate the temperature of the coil for each of the plurality of parts from the operating conditions of the rotating electric machine, and changing the current flowing through the coil for each of the plurality of parts according to the temperature of the coil for each of the plurality of parts calculated by the arithmetic device.

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