Rotary electric machine and method for producing stator in rotary electric machine

Abstract

The stator coil of a rotary electric machine according to the present invention is constituted using concentric winding. The stator coil is constituted by inserting hairpin-shaped coil pieces 10, 11, 20, 21, 30, 31 of rectangular wires from one and the other sides and connecting the coil pieces. The length of a linear part of the coil pieces is set to half of the axial length of the stator core, and at both leg end parts, a protrusion and a recess are engaged with a protrusion shape or a recess shape. The coil pieces are constituted by the following three types: center coil pieces 10, 11 that make connection between slots in the circumferential direction in the vicinity of the center of the slot in the radial direction; inner coil pieces 20, 21 that make connection between the coil end parts in the circumferential direction at a position further inward in the radial direction than the radial position of the slot; and outer coil pieces 30, 31 that make connection in the circumferential direction at a position further outward in the radial direction. The lengths of the coil parts of the connected center coil pieces 10 and 11, coil pieces 20 and 31, and coil pieces 30 and 21 which are concentric are set to be identical so that the resistance values are uniform, and assembly workability is improved.

Description

Rotating electric machine and method for manufacturing stator for rotating electric machine

[0001] The present invention relates to a rotating electric machine having a stator structure in which the stator coils of a radial gap type rotating electric machine are concentrically wound with coils having different coil end shapes for each phase, thereby making it possible to make the electrical resistance value the same for each phase, a manufacturing method for a stator of a rotating electric machine, and a control system for the rotating electric machine.

[0002] High efficiency is required for rotating electric machines (motors) used as power sources for industrial machinery and for driving automobiles. To increase the efficiency of rotating electric machines, it is necessary to reduce losses in the machine, and a common design method is to consider designs that reduce the two major causes of losses in rotating electric machines: coil copper loss and iron core iron loss. Once the required output characteristics (rotation speed and torque) of the rotating electric machine are determined, mechanical loss is uniquely determined, so it is important to design to reduce iron loss and copper loss. Iron loss can be reduced by using soft magnetic materials. In general rotating electric machines, electromagnetic steel sheets are used in the iron core, and different loss levels are used depending on the thickness, Si content, etc. Soft magnetic materials include iron-based amorphous metals, which have higher magnetic permeability and lower iron loss than electromagnetic steel sheets, finemet, and other high-performance materials such as nanocrystalline materials that are expected to have high magnetic flux density. However, these material systems have many challenges in manufacturing rotating electrical machines inexpensively, such as the fact that the plate thickness is very thin at 0.025 mm and the hardness is 900 on the Vickers hardness scale, which is more than five times that of electromagnetic steel sheets. As a result, these high-performance materials cannot be applied to rotating electrical machines.

[0003] Copper loss is primarily determined by the relationship between the coil's resistance and current, so measures are taken to reduce coil resistance through cooling or current by preventing a decrease in the magnet's residual magnetic flux density. In recent years, automotive drive motors and other motors have been designed to minimize resistance to the theoretical limit by increasing the ratio of conductor to the cross-sectional area of ​​the stator slot (space factor). However, coils using rectangular wire, which can achieve a high space factor within the slot, have a complex structure for the coil ends that extend from both ends of the slot to the outside. Connecting these conductors by welding or other methods increases the volume (wire length) of the coil ends, resulting in problems such as a slight increase in resistance.

[0004] Patent Literature 1 discloses a technique in which two hairpin-shaped conductor segments are inserted into a motor stator coil, each segment is bent at the coil end on the opposite side of the insertion, and then welded to the bent conductor of another hairpin-shaped coil arranged circumferentially to form a circular coil. While this method is effective in increasing the slot space factor, it requires bending a thick, hard rectangular conductor during manufacturing, which can cause stress on the stator core, damage to the slot insulator, residual stress from bending at the connection, and difficulty in ensuring the reliability of the welded joint. Therefore, there is room for improvement in this manufacturing method. Furthermore, because space must be secured around the weld for welding, the coil end becomes larger on the welding side.

[0005] One known method that attempts to improve these problems is the technology described in Patent Document 2. Patent Document 2 describes a method for firmly joining the coil mechanically by using a press-fit tolerance for the tip shape of the coil. Patent Document 2 also uses a resin bobbin to firmly secure the coil insertion area and join the uneven tip by applying stress, thereby enabling a highly reliable connection.

[0006] The stator structures using rectangular wires shown in Patent Documents 1 and 2 employ a winding structure called wave winding. This is because the coil shape is consistent circumferentially, facilitating the formation of hairpin-shaped coils and the subsequent twisting and welding after insertion. In a wave winding structure, all coils are connected circumferentially, so the number of coils per phase is equal to the number of slots per pole per phase. This has the drawback of limited design flexibility, such as the need to increase the number of slots when increasing the number of parallel coils. In terms of design flexibility, wave winding requires an even number of turns per slot. When the number of slots per pole per phase is two, two coils, system 1 and system 2, are configured. However, the coils for system 1 and system 2 are evenly staggered and positioned in the same slot, resulting in significant magnetic interference between the two coils. This magnetic interference can disrupt the current waveform when the two coils are controlled and driven independently, due to mutual induced electromotive forces caused by misalignment of current application timing, for example.

[0007] A possible solution to the above problem is to use a concentrically wound coil configuration. In the manufacture of a typical rotating electric machine, a concentrically wound stator is manufactured by winding a bundle of thin round wires to form a coil, and then inserting the coil into a stator slot using a device called an inserter. Patent Document 3 shows a method of assembling a coil wound while pre-arranging the coil shape into a stator core.

[0008] JP 2011-239651 A International Publication No. 2020 / 017133 JP 2011-160572 A

[0009] In the manufacturing method using the technology disclosed in Patent Document 3, the coils are assembled in the axial direction or in the direction from the inner diameter to the outer diameter of the semi-closed slots where the tips of the teeth are shaped like flanges, which means that it is not possible to increase the ratio of the conductor cross-section to the cross-sectional area of ​​the slot, i.e., the space factor. Also, because the shape of the coil ends differs for each phase depending on the insertion order, it is difficult to produce coils with uniform resistance and inductance values.

[0010] The present invention was made in consideration of the above-mentioned background, and its purpose is to provide a concentrically wound stator for a rotating electric machine that combines hairpin-shaped conductors (coil pieces) made of rectangular wire to increase the space factor within the slots and to design the coil end shapes of the coils of each phase so that they do not interfere with each other. It also provides a stator coil configuration that allows the coil lengths of each coil layer to be the same, thereby making the coil resistance and coil inductance the same. Furthermore, it provides a rotating electric machine with improved stator coil assembly.

[0011] The present invention provides a method for solving the above-described problems, for example, as follows. According to one feature of the present invention, the stator coil of a distributed winding radial gap type rotating electric machine is configured to connect slots to achieve a concentric winding structure using hairpin-shaped or U-shaped coil pieces made of rectangular wire. The length of the straight portion of the coil piece is approximately half the axial length of the stator core, and both leg ends of the coil piece are formed with a convex or concave shape that allows them to fit. The coil end shapes of the coil pieces for each phase to form the concentric winding are different for each phase, and three types are prepared: a center coil piece with a structure that connects slots circumferentially with the slots' radial positions (insertion holes) at the same position or offset by one insertion hole; an inner coil piece with a shape that connects coil ends circumferentially with the slots' radial positions shifted radially inward; and an outer coil piece with a shape that connects coil ends circumferentially with the slots' radial positions shifted outward. In this case, the perimeter of the coil is longer for the coil connected radially outward than for the coil connected radially inward, because the outer diameter results in a longer coil end length, increasing the perimeter and resistance. To balance this, the coil on one axial side is connected as an inner coil end, and the other axial coil is connected as an outer coil end. This eliminates the difference in coil perimeter between the inner and outer coil pieces, balancing the coil resistance. The central coil, connected circumferentially near the radial center of the slot, is designed to have the same perimeter as the coil created by connecting the inner and outer coil pieces, i.e., to match the resistance. This allows the coil resistance and inductance to be homogenized, even though it is a concentrically wound coil constructed using flat rectangular conductors.

[0012] According to another feature of the present invention, the coil pieces are formed from rectangular wire and have two straight portions that are to be accommodated in circumferentially spaced slots, and coil end portions that extend outward in the direction of the rotation axis from the straight portions and connect the two straight portions. The coil end portions are formed by two extended portions that extend outward in the direction of the rotation axis from the straight portions of the coil pieces and connecting portions that circumferentially connect the ends of the extended portions. After the stator coil is connected, the connecting portions of the central coil pieces are arranged side by side in the radial direction, and the extended portions of the inner coil pieces are angled so that they bend radially inward, so that the connecting portions of the inner coil pieces are stacked in the direction of the rotation axis at a position radially inward from the stacked portions of the central coil pieces. The extended portions of the outer coil pieces are angled so that they bend radially outward, and the connecting portions of the outer coil pieces are stacked in the direction of the rotation axis at a position radially outward from the stacked portions of the central coil pieces. The angle of the inward bent portion of the extended material portion relative to the straight portion of the inner coil piece is preferably greater than 0 degrees and less than 45 degrees, and the angle of the outward bent portion of the extended material portion relative to the straight portion of the outer coil piece is preferably greater than 0 degrees and less than 45 degrees. If the inner coil piece and outer coil piece are shaped as described above, when inserting the coil pieces into the slots of the stator core from both sides in the rotation axis direction, the central coil piece, inner coil piece, and outer coil piece can be inserted and assembled one by one in order in the rotation axis direction.

[0013] According to another feature of the present invention, the stator core is composed of a core-back core and multiple tooth cores that are combined with the core-back core, and the tooth cores are made of a low-loss soft magnetic material. Furthermore, resin bobbins that accommodate multiple rectangular wires in the radial direction are each disposed in the slots between adjacent tooth cores. To improve coil assembly, the stator core may be split along the rotation axis.

[0014] The above coil configuration allows for the construction of concentrically wound coils with a high conductor space factor and minimal variation in coil resistance between phases. This allows for motor and system designs that take advantage of the features of a concentrically wound coil configuration. Furthermore, the number of coils can be determined independently of the number of slots per pole per phase, increasing the flexibility of series and parallel circuits and facilitating design changes to accommodate different voltage specifications and frequencies (rotation speed, torque). In other words, concentric winding allows for an odd number of turns per slot, which is not possible with wave winding, thereby increasing the design flexibility to accommodate the above-mentioned specification changes. Furthermore, because the coils are structured independently between systems, magnetic interference is reduced, reducing the number of drive circuits required. Furthermore, by optimizing the coil insertion order during the stator coil concave-convex fitting assembly process, the coils can be connected simultaneously during insertion and concave-convex fitting, significantly improving stator assembly.

[0015] 1A is a perspective view showing a coil shape (one pole for three phases) that realizes concentric winding of flat rectangular conductors in a stator of a radial gap type rotating electric machine 1 according to an embodiment of the present invention. FIG. 1B is a lead wire side projection view as seen from one side of the rotation axis of FIG. 1A. FIG. 1C is a counter lead wire side projection view as seen in the direction of arrow 70 from the other side of the rotation axis of FIG. 1A. FIG. 1D is a perspective view of the stator core 3 of FIG. 1. FIG. 1E is an axial projection view of the stator core 3 of FIG. 1 (before a resin bobbin 65 is attached). FIG. 1F is a perspective view of the bobbin 65 alone as seen from one side. FIG. 1G is a perspective view of the bobbin 65 alone as seen from the other side. FIG. 1H is an axial projection view of the stator core 3 of FIG. 1 (after the bobbin 65 is attached). FIG. 1H is a partial projection view as seen from the counter lead side 2b of the stator 2 shown in FIG. 1. FIG. 3A is a perspective view from the inside. FIG. 3B is a perspective view of the center coil piece 11 shown in FIG. 3B. FIG. 3B is a perspective view of the inner coil piece 21 shown in FIG. 3B. FIG. 3C is a perspective view of the outer coil piece 31 shown in FIG. 3B. FIG. 3D is a partial view as seen from the lead side 2a of the stator 2 shown in FIG. 1. 5A is a perspective view of the stator 2 shown in FIG. 4A, as seen from the inside. 5B is a perspective view of the central coil piece 10 shown in FIG. 4B. 5C is a perspective view of the inner coil piece 20 shown in FIG. 4B. 5D is a perspective view of the outer coil piece 30 shown in FIG. 4B. 5E is a perspective view of the lead coil piece 41 (the same applies to lead coil pieces 42 to 46) shown in FIG. 4B. 5F is a perspective view of the entire stator 2 after coil formation of the rotating electric machine 1 of this embodiment. 5G is a projection view of the lead side 2a of the stator 2 shown in FIG. 5A. 5H is a perspective view of the opposite lead side 2b of the stator 2 shown in FIG. 5A (however, the axis of rotation is inverted). 5G is a diagram showing a conventional stator 202, showing the configuration of one phase of a stator 202 with a wave winding coil structure using rectangular wire. 5H is a circuit diagram showing a two-parallel delta connection method for the stator 202. 5H is a connection diagram of the stator 202. 5H is a perspective view of another conventional stator 202A, showing the configuration of one phase of a stator with a wave winding structure using rectangular wire. 8A is a circuit diagram showing a two-series delta connection method for the stator 202A. FIG. 9A is a connection diagram of the stator 202A. FIG. 9B is a perspective view showing the configuration of one phase of the stator 2 having a concentric winding structure using rectangular wires in the rotary electric machine 1 of this embodiment. FIG. 9C is a circuit diagram showing a two-parallel delta connection method for the stator 2 of FIG. 8A. FIG. 9D is a connection diagram of the stator 2 of FIG. 9A. FIG. 9E is a perspective view showing the configuration of one phase of the stator 2 having a concentric winding structure using rectangular wires in the rotary electric machine 1 of this embodiment. FIG. 9F is a circuit diagram showing a two-series delta connection method for the stator 2 of FIG.13A is a diagram showing the coil slot arrangement model of a stator 2 with a wave winding structure using rectangular wire according to a conventional example. FIG. 14B is a diagram showing the flux linkage of the stator 2 of FIG. 13A. FIG. 15A is a diagram showing the flux linkage calculation result by magnetic field analysis using the model of FIG. 15A. FIG. 16A is a diagram showing the coil slot arrangement model of the stator 2 with a concentric winding structure using rectangular wire according to this example. FIG. 16B is a diagram showing the flux linkage of the stator 2 of FIG. 14A. FIG. 16B is a diagram showing the flux linkage calculation result by magnetic field analysis using the model of FIG. 15A. FIG. 16B is a diagram showing the order of assembling the concentric winding stator of this example, and is a projection view of the insertion assembly side (lead side) of the stator 2 in step 1. FIG. 16C is a diagram showing the order of assembling the concentric winding stator of this example. FIG. 16B is a diagram showing the insertion assembly side (lead side) of the stator 2 in step 1. FIG. 16C is a perspective view of the stator 2 in the state of FIG. 16A. 16B is a projection view of the insertion and assembly side (lead side) of the stator 2 in step 2 following Fig. 16A. Fig. 16C is a perspective view of the stator 2 in the state of Fig. 16C. Fig. 16D is a projection view of the insertion and assembly side (lead side) of the stator 2 in step 3 following Fig. 16C. Fig. 16E is a perspective view of the stator 2 in the state of Fig. 16E. Fig. 16F is a projection view of the insertion and assembly side (lead side) of the stator 2 in step 4 following Fig. 16E. Fig. 16G is a perspective sectional view showing an air compressor 100 driven by a rotating electric machine of the present invention.

[0016] Hereinafter, an embodiment of a rotating electric machine 1 of the present invention will be described with reference to the drawings. The following description shows a specific example of the contents of the present invention, and the present invention is not limited to these descriptions. Various changes and modifications can be made by those skilled in the art within the scope of the technical ideas disclosed in this specification. Furthermore, in all drawings used to explain the present invention, parts having the same function are designated by the same reference numerals, and repeated description thereof may be omitted.

[0017] The rotating electric machine 1 of this embodiment is used to drive various devices. FIG. 17 shows an example of such a device, a screw-type air compressor 100 driven by the rotating electric machine 1. The air compressor 100 includes the rotating electric machine 1, which supplies rotational power, and an air end 101, which generates compressed air using the rotational force of the rotating electric machine 1. The rotating electric machine 1 is a so-called interior permanent magnet synchronous motor, and includes a rotor 6 and a stator 2 housed within a housing 4. The housing 4 is composed of a cylindrical body 4a having openings on the front and rear sides, a front end bracket 4b attached to the front opening of the body 4a, and a rear end bracket 4c attached to the rear opening of the body 4a. A through hole is formed in the front end bracket 4b, and one end of the rotating shaft 5, to which the rotor 6 is fixed, protrudes from the interior of the housing 4 toward the front side. The stator 2 includes a stator core 3 and a stator coil 9 wound around the stator core 3. FIG. 17 shows a schematic view of the shape of the end core portion of the stator coil 9, and the detailed shape thereof is the shape shown in FIGS. 1 to 5, which will be described later.

[0018] The M rotor 120 of the air end 101 is connected to the rotating shaft 5 of the rotating electric machine 1 by a connecting means (e.g., a spline, a coupling, a gear, etc.) and supplies rotational power from the rotating electric machine 1 to the first shaft 105 of the air end 101. In this example, the rotating shaft 5 and the first shaft 105 are directly connected, and their rotation axis is Ax. A first bevel gear 110 is provided at the tip of the first shaft 105, and the bevel gear 110 is meshed with an adjacent second bevel gear 130, causing the second bevel gear 130 to rotate at a uniform speed in the opposite direction to the first bevel gear 110. Because the second bevel gear 130 is provided at the tip of the second shaft 135, the rotation of the second bevel gear 130 causes the F rotor 140 fixed to the second shaft 135 to rotate at a uniform speed in the opposite direction to the M rotor 120 fixed to the first shaft 105.

[0019] As the rotating electric machine 1 rotates, the M rotor 120 and the F rotor 140 rotate, and air is sucked in through the suction port of the M rotor 120 (not shown in the figure). As the M rotor 120 and the F rotor 140 further rotate, the teeth of each rotor disengage, and air is sucked into the tooth space. When the M rotor 120 and the F rotor 140 further rotate and the air is blocked by the wall of the casing 102, the suction is completed. The air trapped between the tooth space and the casing is compressed by the meshing of the rotors 120 and 140. As the rotors 120 and 140 rotate in this way, the air moves axially and is further compressed between the tooth space 145 and the casing 102, reaching a discharge port (not shown in the figure) and reaching a predetermined pressure. The compressed air is discharged from the discharge port opened in the casing 102.

[0020] 1A is a partial perspective view of a stator 2 of a rotating electric machine 1 according to an embodiment of the present invention. The rotating electric machine 1 of this embodiment is a radial gap type, and the coils of the stator 2 use so-called rectangular conductor wires (hereinafter referred to as "rectangular wires") whose cross section perpendicular to the longitudinal direction is rectangular. The stator coil 9 is formed by concentrically winding this rectangular wire. FIG. 1A partially shows the shape of one pole, three phases of the stator coil 9.

[0021] The stator 2 has a total of 48 slots and eight rotor poles. Coil pieces 10, 11, 20, 21, 30, 31, 41 to 46 arranged in each slot are rectangular wires with a rectangular cross section. Here, the stator 2 is divided into two parts along the rotation axis Ax, namely, a lead side 2a and a counter-lead side 2b. The lead side 2a of the stator coil 9 uses multiple coil pieces (10, 20, 30) that connect the slots, and multiple lead coil pieces 41 to 46 that are drawn out for connecting the stator coil 9. The counter-lead side 2b uses multiple coil pieces (11, 21, 31) that connect the slots of the stator core 3. A concentrically wound coil (called a U-phase coil) is formed by combining coil pieces (10, 20, 30) that are structured to connect the slots of the stator core 3 on the outlet side 2a in the circumferential direction of the slots, and coil pieces (11, 21, 31) that are structured to connect the slots of the stator core 3 on the opposite outlet side 2b in the circumferential direction at the same diameter as the radial position of the slots 3c.

[0022] The detailed shape of the stator core 3 will now be described using Figures 2A to 2E. Figure 2A is a perspective view of the stator core 3 alone on the lead side 2a, showing the bobbin 65 attached but without the stator coil 9 wound around it. Figure 2B is a partial enlarged view (however, without the bobbin 65) viewed from one side (lead side) of the rotation axis direction of Figure 2A. As shown in Figures 2A and 2B, the stator core 3 has a core-back core 3a formed on the outer periphery. The teeth portion is made of a total of 48 slots 3c arranged circumferentially by arranging tooth cores 3b formed by laminating amorphous metal foil strips cut into trapezoidal shapes. In a rotating electric machine 1 that rotates at high speeds, the supplied voltage is high-frequency, resulting in large iron loss in the teeth portion. Therefore, it is desirable to construct the teeth portion using a low-loss magnetic material. In this embodiment, the teeth portion is manufactured from a material different from the material (electromagnetic steel sheet) of the core-back core 3a portion. Instead of amorphous, the teeth may be made of Finemet, a nanocrystalline alloy material, or a nanocrystalline alloy with high saturation magnetization. Also, if the teeth are made of the same material as the core-back core 3a, such as electromagnetic steel sheet, using a low-iron-loss material, such as a thin steel sheet containing 6.5% Si, can be said to be a way to improve characteristics.

[0023] As shown in Figure 2B, the stator core 3 is constructed by combining tooth cores 3b, each with a trapezoidal cross section perpendicular to the rotation axis, and a core-back core 3a made of electromagnetic steel sheet to hold the tooth cores 3b. The core-back portion has a relatively low magnetic flux density compared to the tooth portion and is less affected by harmonics, so a relatively low-loss material can be used. This structure is designed in part because amorphous alloys are difficult to stamp into complex shapes, so a trapezoidal cross section can be achieved simply by cutting. A resin bobbin 65 is attached to fit this combined core shape for insulation. Figure 2C is a perspective view of the bobbin 65 from the inner periphery, and Figure 2D is a perspective view of the bobbin 65 from the outer periphery.

[0024] The bobbin 65 is formed to be half the overall length of the stator core 3 in the rotational axis direction, i.e., approximately the same length as the lead end 3a and the opposite lead end 3b of the stator core 3 (strictly speaking, the bobbin 65 is longer by the length of the flanges 67 and 68), and has the same width as the slot 3c when viewed in the circumferential direction. Inside the bobbin 65, m (here, m = 4) insertion holes 66a to 66d are formed radially from the inside to the outside, into which rectangular conductors are inserted parallel to the rotational axis direction. Partition walls are provided at the boundaries between the insertion holes 66a to 66d, ensuring that each coil piece is reliably insulated. Flanges 67 and 68 are provided at both axial ends of the bobbin 65, which also function to hold the bobbin 65 in the axial direction against the end faces of the teeth core 3b. Claw portions 67a, 68a with claw-like protruding contours are formed on the inner circumferential sides of the flange portions 67, 68, and the bobbins 65 are assembled by inserting them from the radially inner side toward the outer side of the stator core 3. At this time, the claw portions 67a, 68a are fitted into recesses 3d formed on the inner circumferential side of the core-back core 3a and continuing in the direction of the rotation axis. When all the bobbins 65 are assembled into the slots 3c of the stator core 3, the tooth cores 3b are constrained in the axial direction as well as the circumferential direction. Figure 2E is a diagram showing the state in which the bobbins 65 have been attached from the state shown in Figure 2B.

[0025] Returning to Figure 1 again, a concentrically wound coil (hereinafter, a coil with this structure will be referred to as a V-phase coil) is configured by combining inner coil pieces 20, which connect the slots 3c of the stator 2 on the lead side 2a with coil ends located radially inward of the conductors entering the slots, and outer coil pieces 31, which connect the slots of the stator 2 on the opposite lead side 2b radially outward of the radial position of the conductors.

[0026] Furthermore, a concentrically wound coil (hereinafter, a coil with this structure will be referred to as a W-phase coil) is formed by combining outer coil pieces 30 having a shape in which the coil ends are positioned outside the radial position where the conductors enter the slots and connect the slots of the stator 2 on the outlet side 2a, and inner coil pieces 21 having a structure in which the slots of the stator 2b on the opposite outlet side are connected radially inside the radial position of the conductors.

[0027] As described above, since the coil ends (coil pieces 20, 21) that pass through the inner periphery are shorter in length than the coil ends (coil pieces 30, 31) that pass through the outer periphery, when connecting the coils, the outer coil pieces 30 on the outer periphery are combined with the inner coil pieces 21, and similarly, the outer coil pieces 31 on the outer periphery are combined with the inner coil pieces 20, and the coil lengths of these are made the same as the length of the central coil pieces 10 and 11 to form the U-phase, V-phase, and W-phase coils, thereby preventing differences in resistance values ​​from occurring between the U-phase, V-phase, and W-phase. Furthermore, the portions (coil end portions) of the coil pieces 20 and 21 that are exposed from the stator core 3 are tilted inward, and the coil end portions are wired in a manner that stacks them in the direction of the rotation axis, and the portions (coil end portions) of the coil pieces 30 and 31 that are exposed from the stator core 3 are tilted outward, and the coil end portions are stacked in the direction of the rotation axis. This has the advantage that when inserting each coil piece (10, 11, 20, 21, 30, 31) and lead coil pieces 41 to 46 into slots 3c from both sides of the stator core 3 in the axial direction, the stator coil 9 can be assembled by inserting all of the coil pieces in order parallel to the axial direction.

[0028] 1B and 1C, when coil pieces 10, 11 are arranged so as to connect two slots in the circumferential direction at the same diameter as the radial position of the slots, the coil coming out of the slot in the part hidden by the coil must be connected to the other by a route that passes through either the inner or outer circumferential side, and it is necessary to form a shape that does not interfere with them even when they are arranged in the circumferential direction every 180 electrical degrees. Although only one pole of the formed coils is shown in Figures 1A to 1C, this structure is repeated every 180 electrical degrees (45 mechanical degrees), and by arranging coil pieces in all slots in the circumferential direction, the stator coil 9 of the rotating electric machine 1 is completed.

[0029] Figures 3A to 3E are diagrams illustrating the structure of the non-lead side 2b of the stator 2 shown in Figure 1. Figure 3A shows a portion of the stator coil 9 on the non-lead side 2b projected in the direction of the rotation axis from the arrow 70 side in Figure 1, and Figure 3B is a perspective view from the inner circumferential side. Note that the illustrated coil pieces 11 and coil pieces 21 in Figures 3A and 3B are circumferentially offset from the view from the arrow 70 side in Figure 1A. The central coil piece 11, whose coil end is positioned at the same diameter as the conductor insertion position of slot 3c, has four different radially sized coil pieces 11 arranged in such a way that they connect from one of the four slot insertion holes 66a to 66d in the bobbin 65 to four insertion holes five slots apart circumferentially. In this case, the insertion holes 66a to 66d, counted from the inner circumferential side into which one end of the coil piece 11 is inserted, are numbered the same. For this reason, four types of coil pieces 11 having different sizes are prepared.

[0030] FIG. 3C shows a perspective view of the shape of the central coil piece 11. The coil piece 11 is a conductive wire formed by baking insulating enamel onto a rectangular annealed copper wire. The coil piece 11 is comprised of linear portions 11a and 11e that are accommodated in the slots 3c, extended portions 11b and 11d that are connected to the linear portions 11a and 11e, respectively, and extend outward in the direction of the rotation axis from the slots 3c, and a connecting portion 11c that connects the ends of the extended portions 11b and 11d to the connecting portion. The coil piece 11, which is comprised of the portions 11a to 11e, is formed by bending a rectangular wire into a generally U-shape, like a hairpin. Due to the overall arrangement space of the stator coil 9, in order to secure an area on the inner periphery of the connecting portion 11c of the coil piece 11, the extended portions 11b and 11d of the coil piece 11 are slightly bent radially outward at an angle θ ４ It is preferable to bend the wire by only θ ４ (The radius of curvature of the extension portion 11b and the connecting portion 11c may be less than a dozen degrees.) The radius of curvature of the connection portion between the extension portion 11b and the connecting portion 11c is relatively small so as not to interfere with other coil pieces. Similarly, the radius of curvature of the connection portion between the extension portion 11d and the connecting portion 11c is also relatively small.

[0031] The end legs of the central coil piece 11 are shaped like recesses 11f and 11g. This shape is achieved by punching out the inner peripheral portion of the recess using a press or the like, and then forming a plating layer of approximately 10 μm thick on the cut cross section using electrolytic tin plating. Since the outer skin of the coil piece 11 is covered with enamel, no plating layer is formed, and only the cut surface is plated with the plating layer. As shown in FIG. 3B , the radially inner portion of the connection portion 11c of the central coil piece 11 is arranged so that portions of the coil ends (extended portions 21b and 21d) of the inner coil piece 21 partially overlap in the direction of the rotation axis, and similarly, portions of the coil ends (extended portions 31b and 31d) of the outer coil piece 31 partially overlap in the direction of the rotation axis.

[0032] The inner coil piece 21 is formed in a substantially U-shape and is formed by linear portions 21a and 21e, extension portions 21b and 21d extending outward in the rotation axis direction from the slot 3c, and a connecting portion 21c connecting the ends of the extension portions 21b and 21d spaced apart in the axial direction. The extension portions 21b and 21d of the coil piece 21 are angled θ with respect to the linear portions 21a and 21e. ５ Furthermore, in order to ensure the arrangement space of the entire stator coil 9 at the portion of the coil piece 21 that is more inward than the connecting portion 21c, and in order to prevent interference with other coil pieces, the bending radius R of the connecting portion between the extension portion 21b and the connecting portion 21c and the bending radius R of the connecting portion between the extension portion 21d and the connecting portion 21c must be relatively small.

[0033] The outer coil piece 31 is formed in a substantially U-shape and is formed by linear portions 31a and 31e, extension portions 31b and 31d extending outward in the rotation axis direction from the slot 3c, and a connection portion 31c connecting the ends of the extension portions 11b and 11d spaced apart in the axial direction. The extension portions 31b and 31d of the coil piece 31 are angled θ with respect to the linear portions 31a and 31e. ６ Furthermore, in order to ensure the arrangement space of the entire stator coil 9 at the outer circumferential portion of the coil pieces 31 than the connecting portion 31c, and also in order to ensure the arrangement space at the outer circumferential portion of the coil pieces 31, the bending radius R at the connecting portion between the extension portion 31b and the connecting portion 31c and the bending radius R at the connecting portion between the extension portion 31d and the connecting portion 31c need to be relatively small so as not to interfere with other coil pieces.

[0034] When the inner coil pieces 21 are assembled as shown in Fig. 3B, the four connection portions 21c are arranged to overlap in the direction of the rotation axis. Similarly, four different sized outer coil pieces 31 are prepared, and when they are assembled as shown in Fig. 3B, the four connection portions 31c are arranged to overlap in the direction of the rotation axis.

[0035] As shown in Figure 3B, the connection portions 11c of the four central coil pieces 11 are prepared in four different sizes and are arranged radially from the inside to the outside at the same position in the rotation axis direction from the inside to the outside. The shape of the connection portions 11c is not linear, but is formed in an arc shape that extends in the circumferential direction along the circumferential direction of the stator core 3. The height of the coil end portion of the coil piece 11 (height from the end of the stator core) is h ４ The four inner coil pieces 21 are prepared in four different sizes, and their connection portions 21c are arranged side by side at the same radial position so as to be stacked in the axial direction. The shape of the connection portions 21c is not linear, but is formed in an arc shape along the circumferential direction of the stator core 3. The maximum height of the coil end portions of the stacked coil pieces 21 (maximum height from the end of the stator core) is h ５ Furthermore, four different sizes of outer coil pieces 31 are prepared, and their connection parts 31c are arranged side by side at the same radial position so as to be stacked in the axial direction. The shape of the connection parts 31c is not linear, but is formed in an arc shape along the circumferential direction of the stator core 3. The maximum height of the coil end parts of the stacked coil pieces 31 (maximum height from the end of the stator core) is h ６ Here, the height h ４ >h ５ , and h ４ >h ６ It is desirable to have the following relationship. ５ and ６ The magnitude relationship between these is arbitrary.

[0036] As described above, the inner coil pieces 21 are formed by bending the rectangular wire rising from the straight portions 21a and 21e radially inward so as not to interfere with the connection portions 11c of the four central coil pieces 11 and not to protrude further inward than the innermost diameter portion of the stator core 3. As shown in Figure 3B, the coil pieces 21 rising from the radially inner side of the slot 3c are configured to have the lowest coil height, and the coil pieces 21 at the next radial position are positioned higher to ensure the wire thickness and a slight gap so that the connection portions 21c are located above the innermost coil piece 21. The connection portions 21c of the coil pieces 21 rising from the next radial position (the third insertion hole from the inside) are positioned even higher, and the connection portions 21c of the coil pieces 21 rising from the next radial position (the fourth insertion hole from the inside) are positioned even higher. Like the central coil piece 11, the inner coil piece 21 also has recesses 21f and 21g formed at the coil ends (the ends of the straight portions 21a and 21e opposite the coil ends), and the cut surfaces are tin-plated.

[0037] In Figure 3B, the bobbin 65 is omitted only for the portion of the slot 3c where the coil piece 21 is inserted, so that the shape and location of the ends (21f, 21g) of the coil piece 21 can be seen. The concave coil piece 21 is set to be shorter than the length of the non-lead side 2b of the stator core 3 in the direction of the rotation axis so as not to protrude from the end of the stator core 3. The recesses 21f, 21g are designed to be fitted with the protrusions 20f, 20g, which will be described later in Figure 4, at a portion located a predetermined distance inward from the end. The axial positions of the recesses 11f, 11g, 31f, 31g formed at the ends of the other coil pieces, i.e., the central coil piece 11 and the outer coil pieces 31, are also the same.

[0038] The outer coil pieces 31 are formed by bending the rectangular wire rising from the straight portions 31a and 31e outward in the radial direction so as not to interfere with the central coil pieces 11. Since the outer coil pieces 11 often have a margin in the core back portion, they can be bent outward significantly. In this embodiment, too, the bending angle θ ６The angle is set to a relatively large angle of about 45 degrees. In this case, as shown in FIG. 3B , the coil pieces 11 rising from the innermost slot insertion holes are configured so that the coil height of the connection portion 11c is the highest, and the coil piece 11 for the second insertion hole is positioned lower to ensure a wire thickness and a slight gap, so that it is positioned below the coil piece 11 rising from the first insertion hole. Similarly, the shape of each coil piece 11 is designed so that the connection portion 11c of the coil piece 11 rising from the third insertion hole from the inside is even lower, and the connection portion 11c of the coil piece 11 rising from the fourth insertion hole is below that. Recesses 31f and 31g are formed in the ends of these outer coil pieces 11, and they are tin-plated, just like the inner coil pieces 31.

[0039] 4A to 4D are partial structural diagrams illustrating the axial configuration (lead wire side) of the stator core 3 that constitutes the stator 2 shown in Fig. 1A, and perspective views illustrating the shapes of each coil. Fig. 4A shows a portion of an axial projection of the lead side 2a of the stator core 3, and Fig. 4B is a perspective view of that. Because lead coil pieces 41 to 46 are present on the lead side 2a of this stator core 3, the way they straddle the slots 3c is different from the case of Figs. 3A and 3B.

[0040] 4C is a perspective view of the central coil piece 10. The coil piece 10 is formed in a hairpin shape, in other words, a substantially U-shape, and is formed by linearly formed straight portions 10a and 10e, extension portions 10b and 10d extending outward from the slot 3c, and a connection portion 10c connecting the ends of the extension portions 11b and 11d spaced apart in the axial direction. Of these, the extension portions 10b and 10d and the connection portion 10c form the coil end portion. The extension portions 10b and 10d of the coil piece 10 are angled θ with respect to the linear portions 10a and 10e. １The coil segments 10 are bent radially outward by only a small radius. Furthermore, in order to ensure sufficient space for the overall arrangement of the stator coil 9 at the outer periphery of the connection portion 10c of the coil segments 10, and to prevent interference with other coil segments, the bending radius of the connection portion between the extension portion 10b and the connection portion 10c and the connection portion between the extension portion 10d and the connection portion 10c are made relatively small. The ends of the coil segments 10 are formed (cut) into protrusions 10f and 10g. These dimensions are appropriate for press-fitting into the recesses 11f and 11g of the symmetrical coil segments 11 (see FIG. 2C). The cut surfaces of the recesses 11f and 11g are tin-plated, just like the protrusions 10f and 10g.

[0041] The lead coil pieces 41-43 are accommodated in the innermost insertion hole 66a among multiple insertion holes 66a-66d formed in the bobbin 65. In the inner coil piece 20, the insertion holes 66b-66d in which the lead coil piece 41 is located form a concentric coil via the outer coil piece 31 (see FIG. 3B) on the opposite lead side 2b, and are connected to 66a-66c in the slots 3c across five slots (37.5 degrees) in the circumferential direction, thereby connecting the lead coil pieces 41 and 44. In the central coil piece 10, the innermost insertion hole 66a in which the lead coil piece 42 is located forms a concentric coil via the central coil piece 11 (see FIG. 3B) on the opposite lead side 2b, and is connected to the lead coil piece 45 in the outermost insertion hole 66d in the slot 3c across five slots in the circumferential direction. The central coil piece 10 is composed of three pieces: a piece connecting the starting slot insertion hole 66b to the slot insertion hole 66a on the side spanning five slots in the circumferential direction, a piece connecting the starting slot insertion hole 66c to the slot insertion hole 66b on the side spanning five slots in the circumferential direction, and a piece connecting the slot insertion hole 66d to the slot insertion hole 66c on the side spanning five slots in the circumferential direction. The outer coil piece 30 has a structure in which the innermost insertion hole 66a where the lead coil piece 43 is located forms a concentric coil via the inner coil piece 21 on the anti-lead side 2b (see Figure 3B), and is connected to the lead coil piece 46 of the outermost insertion hole 66d of the slot 3c spanning five slots in the circumferential direction.

[0042] Figure 4F shows the shape of the lead coil piece 41. The lead coil pieces 41 to 46 have exactly the same shape, so common parts can be used. The lead coil piece 41 is made by bending a nichrome wire with a rectangular cross section into a crank shape. The straight portion 41a, bent portion 41b, and extended portion 41c form a structure in which the nichrome wire has a stepped shape near the center in the longitudinal direction. As shown in Figure 4B, the coil pieces 41 to 46 are dimensionally related so that they do not interfere with the respective coil pieces 10, 20, and 30 when installed.

[0043] 4C, 4D, and 4E are prepared in three types each with slightly different sizes, and lead coil pieces 41 to 46 of the same dimensions are prepared, thereby forming a stator coil 9 for one phase as shown in FIG. 4A on the lead side 2a of the stator 2. The radially inner lead wires (41 to 43) of the stator coil 9 extend inward beyond the innermost position of the stator core 3. In this embodiment, this is because there is no room on the inner side, but if the design allows for more room on the inside, the lead coil pieces 41 to 43 can also be configured to fit outside the inner diameter of the stator 2. In addition, the length of the straight portion of each coil piece (10a, 10e, 20a, 20e, 30a, 30e, 41a, etc.) is formed to be longer than the length of the outlet side 2a of the stator core 3, and the dimensional relationship is configured such that the end where the convex portion of each coil piece (10f, 10g, 20f, 20g, 30f, 30g, 41f, etc.) is formed protrudes into the stator core 3 on the anti-outlet side 2b.

[0044] Fig. 5A is a perspective view of the stator 2 of a radial gap type rotating electric machine 1 according to an embodiment of the present invention, showing all coils mounted circumferentially using concentric windings of flat rectangular conductors. Fig. 5B is a perspective view of the lead side 2a portion of the stator 2 (before joining with the opposite lead side 2b portion), and Fig. 2B is a perspective view of the opposite lead side 2b portion of the stator 2 (before joining with the lead side 2a portion), viewed from the opposite side of the rotation axis (from the direction of arrow 70 in Fig. 1). The lead side 2a stator and the opposite lead side 2b stator are assembled in the direction of the rotation axis, and the recesses (10f, 10g, 20f, 20g, 30f, 30g, 41f, etc.) and the protrusions (11f, 11g, 21f, 21g, 31f, 31g) inside the bobbin 65 on the opposite lead side 2b side are fitted together to form a coil. 1, in order to balance the resistance values ​​of the coils, the inner coil pieces 20 on the lead side 2a and the outer coil pieces 31 on the opposite lead side 2b are combined in the axial direction to form a concentric winding, and the outer coil pieces 30 on the lead side 2a and the inner coil pieces 21 on the opposite lead side 2b are combined in the axial direction to form a concentric winding. Near the center in the radial direction, assembly is performed so that the central coil piece 10 on the lead side 2a and the central coil piece 11 on the opposite lead side 2b are combined to form a concentric winding. Furthermore, when the lengths in the direction of the rotation axis Ax of the stator core 3 on the outlet side 2a and the anti-outlet side, which have a divided structure, are equal, the lengths of the straight portions 10a, 10e, 20a, 20e, 30a, 30e of the coil pieces 10, 20, 30 on the outlet side 2a are made longer than the lengths of the straight portions 11a, 11e, 21a, 21e, 31a, 31e of the coil pieces 11, 21, 31 on the anti-outlet side 2b.

[0045] Next, the winding structure of the stator coil 9 of this embodiment will be described. Before describing the structure of this embodiment, the winding structure of a conventional coil will be described using Figures 6A to 6C and 7A to 7C. Figure 6A is a perspective view showing the configuration of one phase of a stator with a wave winding structure using rectangular wire as a conventional example, Figure 6B is a circuit diagram of a two-parallel delta connection, and Figure 6C is a connection diagram thereof. Figure 6A shows the upper half of Figure 6C.

[0046] The small circled numbers, i.e., circle 1 and circle 8, represent lead wires. The coil leading from circle 1 connects via the lower coil end to the second insertion hole of slot 43, six slots circumferentially away, and then via the upper coil end to slot 37, six slots circumferentially away. It then connects via the lower coil end to slots 31, 25, 19, and 13, connecting to slot 8, which spans five slots circumferentially, with a short-pitch coil 17. The coil then makes one full turn across six slots, spanning slots 2, 44, 38, 26, 20, and 14. It then connects via a long-pitch coil 16 to the third insertion hole, and from slot 1, it makes two turns as described above, before exiting through the fourth insertion hole of slot 8. This becomes the U-phase of system 1, with terminals at circle 1 and circle 8, and is connected as the U-phase coil 18 of system 1 in Figure 6B. Similarly, the U-phase coil that enters from circle 14 and is connected to circle 7 is configured as system 2. This is connected as U-phase coil 19 of system 2 in Figure 6B. As can be seen from this, with wave winding, because divided coil pieces are connected in the circumferential direction, the number of coils cannot be greater than the number of slots per pole per phase, and with 8 poles and 48 slots, there would only be two coils per phase.

[0047] FIG. 7A is a perspective view showing the configuration of one phase of a stator with a wave winding structure using rectangular wire as another conventional example. FIG. 7B is a circuit diagram of a two-series delta connection, and FIG. 7C shows its connection diagram. The wave winding shown in FIG. 6A has two coils, so in addition to the two-delta connection shown in FIG. 6, a one-delta connection can be configured in which two coils of the same phase are connected in series. That is, as shown in FIG. 7B, this configuration is possible by connecting two coils of the same phase, circle 1-circle 8 coil and circle 14-circle 7 coil, in series, and similarly delta-connecting two coils of the same phase in series for other phases. This configuration allows rotating electric machines with multiple voltage specifications, such as 200V and 400V specifications, to be realized with the same winding configuration, simply by changing the wiring. Furthermore, although not shown, a Y-connection is also possible, and two-series, one-Y-connection, and two-Y-parallel connections are also possible. However, since the number of turns cannot be changed, the voltage change is limited to a factor of 1.73.

[0048] Next, the winding structure of the stator coil 9 of this embodiment will be described. FIG. 8A is a perspective view showing the configuration of one phase of a stator with a concentric winding structure using rectangular wire according to the present invention, FIG. 8B is a circuit diagram of a two-parallel delta connection, and FIG. 8C shows the connection diagram. Only the U-phase coil is shown in FIGS. 8A to 8C. Comparing FIG. 8C with FIG. 6C reveals that the U-phase coils are located in the same slot. Since this embodiment is configured with concentric winding, it is composed of eight partial coils (slot numbers 2 and 7, 8 and 13, 14 and 19, 20 and 25, 26 and 31, 32 and 37, 38 and 43, and 44 and 1) in five slots (straddling 37.5 degrees). In FIG. 8C, four concentric winding partial coils are connected in series to form partial coil group 28 of system 1 and partial coil group 29 of system 2. The partial coil group 28 of system 1 is connected to the U-phase coil portion of Figure 8B to form the stator coil 50a, and the partial coil group 29 of system 2 is connected to the U-layer portion of another delta connection to form the stator coil 50b, resulting in the coils of the circuit diagram of Figure 8B.

[0049] Fig. 9A is a perspective view showing the configuration of another single phase of a stator 2 with a concentric winding structure using rectangular wire according to the present invention, Fig. 9B is a circuit diagram of a two-series delta connection, and Fig. 9C shows the connection diagram. As with the conventional example of Fig. 7A, two coil groups 28, 29 can be configured with a concentric winding structure, and these two can be connected in series to correspond to a one-delta connection as shown in Fig. 9B. This makes it possible to configure a motor that is compatible with both 200V and 400V specifications.

[0050] FIG. 10A is a circuit diagram of an 8-parallel delta connection showing another configuration for one phase of a concentrically wound stator 2 using rectangular wire according to the present invention, and FIG. 10B shows the connection diagram. As shown in FIG. 10B, the concentric winding in this embodiment is configured with eight coils 32 to 39. Therefore, up to eight parallel connection configurations are possible. While FIGS. 10A and 10B show an 8-parallel delta connection configuration in which all coils are connected in parallel, as shown in FIG. 10B, eight parallel configurations are possible by connecting one concentrically wound coil 32 to 39 per coil. Naturally, two-series and four-parallel configurations are also possible. This makes it possible to accommodate four voltage specifications.

[0051] Figure 11 is a circuit configuration diagram of a control system for a rotating electric machine when a concentrically wound stator 2 is driven by two inverter devices. For a large-capacity rotating electric machine 1A, dividing the drive circuit (inverter device) into two may reduce circuit manufacturing costs rather than increasing the capacity of the drive circuit (inverter device) and driving a single rotating electric machine with a single drive circuit. Also, in some cases, the rotating electric machine is driven using multiple control circuits to disperse heat generated in the power device portion of the drive circuit. In this case, a system is adopted in which the winding is divided into two and shared by each drive circuit (inverter device).

[0052] FIG. 11 shows the connection configuration, with the control circuit 52a of system 1 connected to the stator coil 50a of system 1, and the control circuit 52b of system 2 connected to the stator coil 50b of system 2 for drive. The power supplies of the control circuits 52a and 52b are connected to separate systems, and separate rectifier circuits 51a and 51b generate separate direct currents to drive the rotating electric machine through PWM (Pulse Width Modulation) switching. Although not shown in FIG. 11, a drive device having a microcomputer is provided to control the on / off of the gate signals of the control circuits 52a and 52b. When using these configurations, it is clear that the rotating electric machine 1 must have two or more sets of windings, such as 50a and 50b. In the wave winding examples shown in Figures 6A and 7A, only two in-phase windings are possible, so although it is possible to switch between 200V and 400V specifications, it becomes impossible to use a drive system using two control circuits when using the 400V specification (two in series, one delta connection). In other words, in order to switch voltage specifications and drive two control circuits with a rotating electric machine 1 with a single winding specification, four or more coils per phase are required. This is possible with the concentric winding structure of the present invention, which allows for separation into up to eight coils.

[0053] Figure 12 shows a coil slot arrangement model of a stator 202 with a wave winding structure using rectangular wire, and Figures 13A and 13B show the results of magnetic flux linkage calculations using this model through magnetic field analysis. When two coil groups are driven using two control circuits, as in Figure 11, magnetic interference between the coils can be a problem. When the coupling coefficient between the two coils is high and the operation of one control circuit does not match that of the other, an induced voltage is generated between the coils, resulting in mutual distortion of the currents. Figure 13A shows the results of magnetic field analysis confirming this phenomenon. Figure 13A shows the slot arrangement for wave winding. As shown in slot 204, coils U1 and U2 of system 1 are intermixed in a staggered manner within a single slot. The same applies to the other phases, with coils V1 and V2 of system 1 intermixed in a staggered manner within a single slot, and coils W1 and W2 of system 1 intermixed in a staggered manner within a single slot.

[0054] Figure 13A shows the flux linkage results for one coil (system 1) when a sine wave is applied to the other coil (system 2). The horizontal axis of Figure 13A is time (unit: seconds), and the vertical axis is flux linkage (Wb). The analysis was performed using three-phase AC, but only the U phase is shown here. The magnetic flux of u1, the side where current is applied, is shown with a solid line, and the magnetic flux of u2, where the flux linkage is detected, is shown with a dotted line. Because the two lines match closely, the graph shows only the solid line. Figure 13B shows the flux linkage and coupling coefficient for all three phases. The coupling coefficient is 1 for all three phases, confirming a high degree of magnetic influence. This means that a wave-wound coil is not suitable for driving with two control circuits.

[0055] FIG. 14 shows a coil slot arrangement model for a stator 2 with a concentric winding structure using rectangular wire according to this embodiment. In a calculation model for concentric winding, only coils of the same system are placed in the same slot. For example, only the V1-phase coil is placed in slot 301. This circuit is for the two-parallel delta connection shown in FIG. 8. The dashed line indicated by reference numeral 71 indicates the boundary between the U1 coil and the U2 coil. FIG. 15B shows the calculation results of the coil flux linkage interference obtained by magnetic field analysis using this model. In the concentric winding configuration, four coils are arranged circumferentially, so it is believed that the influence of coils other than those near the boundary is small. Comparing u1 and u2, unlike the results shown in FIG. 13A, where the two values ​​match, the flux linkage of coil u2 is smaller than that of coil u1, as shown in FIG. 15A. As shown in FIG. 15B, the coupling coefficient is approximately 0.1, indicating small magnetic interference.

[0056] Next, the assembly sequence of the concentrically wound stator 2 according to this embodiment will be described with reference to Figures 16A to 16H. Figures 16A, 16C, 16E, and 16G are projection views of the insertion assembly side (lead side) of the stator 2, and Figures 16B, 16D, 16F, and 16H are perspective views (for one phase) of the stator 2 in the states shown in Figures 16A, 16C, 16E, and 16G, respectively.

[0057] Figure 16A shows the stator core 3 in an assembled state. From this state, coil pieces are inserted into the insertion holes 66a to 66d of the bobbin 65 in the slot 3c while taking into consideration the assembly sequence. Figure 16B is a perspective view of the stator 2 in the state shown in Figure 16A. Figure 16B shows the state in which the assembly of the coil pieces 11, 21, and 31 on the opposite lead side has already been completed.

[0058] Figure 16C shows a state in which, from the state in Figure 16A, lead coil pieces 41 to 43 have been inserted into the inner insertion holes 66a, and lead coil pieces 44 to 46 have been inserted into the outer slot insertion holes 66d. Figure 16D is a perspective view of the stator 2 in Figure 16C. In Figures 16C and 16D, the lead coil pieces 41 to 43 are inserted into the slot at the starting point 60 and the slot one slot away thereafter, so that the lead coil pieces 41 to 43 for one turn in the circumferential direction are inserted. The outer lead coil pieces 44 to 46 are inserted from a position five slots away from the starting point 60, so that the lead coil pieces 44 to 46 for one turn in the circumferential direction are inserted. The lead coil pieces 41 to 46 can be inserted in any order. In other words, the lead wires (41 to 43) are inserted into the inner insertion holes 66a every other slot in the circumferential direction, and the lead wires (44 to 46) are inserted into the outer insertion holes 66d every other slot in the circumferential direction, either in order or in random order. Looking at the projection diagram in Figure 16C, it can be seen that even after inserting the lead coil pieces 41 and 42, the holes of the insertion holes other than the insertion holes into which the lead coil pieces 41 and 42 are inserted are still visible on the projection surface. Similarly, the lead coil pieces 41 to 46 are inserted into the inner insertion holes 66a constituting the other phases every other slot in the circumferential direction. Similarly, the lead coil pieces 44 to 46 are inserted into the outer insertion holes 66d every other slot in the circumferential direction.

[0059] 16E , three inner coil pieces 20 and three outer coil pieces 30 are inserted. The inner coil pieces 20 are inserted into the second insertion hole 66b from the inside of the starting point 60 and the insertion hole 66b five slots away from the starting point 60 in the circumferential direction. Similarly, a coil piece 20 is inserted into the outer insertion hole 66c, and then another coil piece 20 is inserted into the outer insertion hole 66d. In this manner, the inner coil pieces 20 are inserted in order from the second inner insertion hole 66b to the fourth insertion hole 66d. As a result, the coil pieces 20 are stacked so that the connection portion 20c of the coil piece 20 inserted into the insertion hole 66d is located at the top and the connection portion 20c of the coil piece 20 inserted into the insertion hole 66b is located at the bottom. This insertion of three coil pieces 20 at a time is repeated six times (six layers) around the entire circumferential direction, starting again from a position 10 slots away from the starting point 60.

[0060] The outer coil pieces 30 are first inserted into the third insertion hole 66c from the inside of the slot four slots circumferentially away from the starting point 60, and the insertion hole 66c of the slot nine slots circumferentially away from the starting point 60. The outer coil pieces 30 must be inserted in order, starting from outer insertion hole number 3 and moving inward. First, the lead coil pieces 44, 46 are inserted into outer insertion hole number 4, then the coil piece 30 is inserted into insertion hole number 3, then the coil piece 30 is inserted into insertion hole number 2, and finally the coil piece 30 is inserted into insertion hole number 1. At this time, the coil pieces are inserted in order starting with the lowest coil end height by stacking them so that the bent portions 46b of the lead coil pieces 44, 46 are positioned close to the stator core 3, the connection portion 30c of the coil piece 30 inserted into insertion hole No. 3 is positioned next to it in the direction of the rotation axis, and next to that of the connection portion 30c of the coil piece 30 inserted into insertion hole No. 2, and the connection portion 30c of the coil piece 30 inserted into insertion hole No. 1 is positioned furthest from the stator core 3. As shown in the projection view of Figure 16E, even after the coil pieces 20, 30 have been inserted, it can be confirmed that the insertion holes 66a to 66d, indicated by arrows 72a and 72b, for inserting the central coil pieces, are still visible from the direction of the rotation axis.

[0061] Next, as shown in Figures 16G and 16H, three central coil pieces 10 are inserted at the positions indicated by arrows 72a and 72b in Figure 16E. The central coil pieces 10 are first inserted into the outermost insertion hole 66d of the second slot circumferentially from the starting point 60 and the third insertion hole 66c of the seventh slot circumferentially from the starting point 60. Next, the central coil pieces 10 are inserted into the third insertion hole 66c of the second slot circumferentially from the starting point 60 and the second insertion hole 66b of the seventh slot circumferentially from the starting point 60. Finally, the central coil pieces 10 are inserted into the second insertion hole 66b of the slot two slots circumferentially from the starting point 60 and the innermost insertion hole 66a of the slot seven slots circumferentially from the starting point 60. In this embodiment, the coil end portions of the coil pieces 10 are aligned at an angle θ in Figure 4C. １ As shown in FIG. 1, the coil pieces 10 are tilted outward by about 5 degrees, so it is preferable to insert the coil pieces 10 in order from the outer insertion hole No. 4. In addition, the connection portions 10c of the inserted three types of coil pieces 10 are at the same height H in the axial direction. １ The holes are aligned in the radial direction.

[0062] The above-described insertion of the three central coil pieces 10 is repeated six times (six layers) in the entire circumferential direction, starting again from a position 10 slots away from the starting point 60 in the circumferential direction. In this way, assembly of the lead-out side stator coil 9 is completed, and the completed state is as shown in FIG. 5B.

[0063] The assembly sequence for the coil pieces 11, 21, and 31 on the non-lead side of the stator core 3 is essentially the same as the assembly method shown in Figures 16E and 16G. Because the lead wires corresponding to 41 to 46 are not used on the non-lead side 2b, four coil pieces 11, 21, and 31 are inserted. First, the inner coil pieces 21 are inserted into the slots 3c from insertion holes 1 to 4 in order, and this process is repeated circumferentially for eight phases. Next, the outer coil pieces 31 are inserted into the slots 3c from insertion holes 4 to 1 in order, and this process is repeated circumferentially for eight phases. Next, the center coil pieces 11 are inserted into slots 4 to 1 in order, and this process is repeated circumferentially for eight phases, completing the assembly of the coil pieces on the non-lead side 2b. This completed state is shown in Figure 5C. The insertion sequence of these coil pieces does not necessarily have to be as described above. For example, the assembly order of the inner coil pieces 20 and the outer coil pieces 30 may be reversed, with the outer coil pieces 30 being assembled first, followed by the inner coil pieces 20.

[0064] 5B and 5C, the stator core 3 on the lead side 2a and the stator core 3 on the anti-lead side 2b are joined together while temporarily fixing the coil end portions of each coil piece so that they do not move in the direction of the rotation axis, thereby fitting the convex portions of coil pieces 10, 20, 30, 41 to 46 into the concave portions of coil pieces 11, 21, 31. Through this procedure, the mechanical assembly of the stator 2 is completed.

[0065] As can be seen in Figure 6A, the wave-wound coil pieces of the conventional example have adjacent coil pieces that cross and intertwine, making it impossible to assemble them one by one. Instead, the coil pieces must be fixed together and installed in the slots 3c all at once before being inserted into the bobbin of the stator core. Also, once assembled, it is difficult to remove the coil pieces one by one. The concentrically wound, concave-convex fitting coil pieces 10, 11, 20, 21, 30, 31 of this embodiment can be said to have an advantage over wave winding in terms of ease of coil assembly.

[0066] As described above, according to the present invention, by combining outer coil pieces 30, 31 with longer coil end lengths relative to the inner coil pieces 20, 21, the central coil pieces 10, 11, which are connected circumferentially at the same diameter as the radial position of the slot, are designed to have the same circumferential length, i.e., resistance, as the coil created by connecting the inner and outer coil pieces. This makes it possible to homogenize the resistance and inductance of the coil, even though it is a concentrically wound coil made using a flat rectangular conductor.

[0067] The coil configuration of the present invention allows for the construction of a concentrically wound stator coil 9 with a high conductor space factor and minimal variation in coil resistance between phases. This enables motor and system designs that take advantage of the features of a concentrically wound coil configuration. Furthermore, since the number of coils can be determined independently of the number of slots per pole per phase, design flexibility is increased when choosing between series and parallel circuits during wiring, facilitating design changes to accommodate different voltage specifications and frequencies (rotation speed, torque). Concentric winding allows for an odd number of turns per slot, which is not possible with wave winding, thereby enhancing design flexibility to accommodate the above-mentioned specification changes. Furthermore, because the coils are structured independently between systems, magnetic interference is reduced, thereby reducing the number of drive circuits that can be used. Furthermore, by optimizing the coil insertion order during the concave-convex fitting assembly of the stator coil, assembly can be performed simultaneously with insertion and concave-convex fitting. The present invention is not limited to the above-described embodiments, and various modifications are possible within the spirit and scope of the invention.

[0068] DESCRIPTION OF SYMBOLS 1, 1A... rotating electric machine, 2... stator, 2a... lead side, 2b... anti-lead side, 3... stator core, 3a... core-back core, 3b... teeth core, 3c... slot, 3d... recess, 4... housing, 4a... body portion, 4b, 4c... end bracket, 5... rotating shaft, 6... rotor, 7... rotor core, 8... permanent magnet, 9... stator coil, 10, 11... central coil piece, 11a, 11e... straight portion, 11b, 11d... extension portion, 11c... connection portion, 15... standard pitch coil, 16... long pitch coil, 17... short pitch coil, 18... U-phase coil of system 1, 19... U-phase coil of system 2, 20, 21... inner coil piece, 28... (first) partial coil group, 29... (second) partial coil group, 30, 31...outer coil piece, 32 to 39...(1 to 8) concentric wound coil groups, 41 to 46...lead coil piece, 50a...(system 1) winding, 50b...(system 2) winding, 51...rectifier (converter), 52a, 52b...control circuit (inverter device), 53a, 53b...system power supply (three phase), 65...resin bobbin, 66a to 66d...insertion hole, 67, 68...flange portion, 67a, 68a...claw portion, 100...air compressor, 101...air end, 102...casing, 105...first shaft, 110...first bevel gear, 120...M rotor, 130...second bevel gear, 135...second shaft, 140...F rotor, 145...tooth form space, 202...stator, Ax...rotation axis

Claims

1. A rotating electric machine comprising: a rotor fixed to a rotating shaft; and a stator in which a coil is formed by inserting and connecting multiple U-shaped coil pieces made of rectangular wire into slots from one or the other side in the rotational axis direction of a stator core in which multiple slots for accommodating multiple rectangular wires are formed in the circumferential direction, wherein the coil pieces are made of rectangular wire and have two straight sections that are to be accommodated in the slots separated in the circumferential direction, and a coil end section that is formed to extend outward in the direction of the rotational axis from the straight sections and connects the two straight sections; the coil pieces include a central coil piece in which the straight sections and the coil end section are arranged on a circumference when viewed in a plan view from the rotational axis direction; an inner coil piece in which the coil end section is bent radially inward with respect to the portion to be accommodated in the slot; and an outer coil piece in which the coil end section is bent radially outward with respect to the portion to be accommodated in the slot, a rotating electric machine characterized in that the circumferential length of the coil end portions of the inner coil pieces is shorter and the circumferential length of the coil end portions of the outer coil pieces is longer than the circumferential length of the coil end portions of the central coil pieces, a pair of the central coil pieces are inserted into the first slot set from one side or the other in the direction of the rotation axis and electrically connected, and the inner coil pieces and the outer coil piece wires are inserted into the second or third slot set from one side or the other in the direction of the rotation axis and electrically connected to form a concentrically wound stator coil.

2. A rotating electric motor as described in claim 1, wherein the coil end portions are formed by two extension portions extending outward in the direction of the rotation axis from the straight portions of the coil pieces and a connection portion circumferentially connecting the ends of the extension portions, and after the stator coil is connected, the connection portions of the central coil pieces are arranged so as to be lined up in the radial direction, and by setting an angle so that the extension portions of the inner coil pieces bend radially inward, the connection portions of the inner coil pieces are arranged so as to be stacked in the direction of the rotation axis at a radially inner portion than the stacked portion of the central coil pieces, and by setting an angle so that the extension portions of the outer coil pieces bend radially outward, the connection portions of the outer coil pieces are arranged so as to be stacked in the direction of the rotation axis at a radially outer portion than the stacked portion of the connection portions of the central coil pieces.

3. A rotating electric motor as described in claim 2, wherein the angle of the inward bend of the extended material portion relative to the straight portion of the inner coil piece is greater than 0 degrees and not greater than 45 degrees, and the angle of the outward bend of the extended material portion relative to the straight portion of the outer coil piece is greater than 0 degrees and not greater than 45 degrees, and the inner coil pieces and the outer coil pieces are alternately connected so that the coil length of one turn is made equal to the coil length of one turn formed by the two central coil pieces.

4. A rotating electric motor as described in claim 3, characterized in that when inserting coil pieces into the slots of the stator core from both sides in the direction of the rotation axis, the central coil piece, the inner coil piece, and the outer coil piece can be inserted and assembled one by one in sequence parallel to the direction of the rotation axis.

5. A rotating electric machine as claimed in claim 1, characterized in that the stator coil is formed by concentric winding, making it possible to configure a number of parallel connections greater than the number of slots per pole per phase.

6. A rotating electric machine as claimed in claim 3, wherein the stator core is composed of a core-back core and a number of teeth cores which are combined with the core-back core, the teeth cores are made of a low-loss soft magnetic material, and a resin bobbin which accommodates a number of rectangular wires in the radial direction is disposed in each of the slots between the adjacent teeth cores.

7. A rotating electric machine according to claim 3, characterized in that it is configured so that a single winding specification can simultaneously accommodate a plurality of voltage specifications and a plurality of control devices.

8. A rotating electric machine according to claim 3, characterized in that an odd number of turns are configured in one of said slots.

9. A control system for a rotating electric machine as claimed in claim 3, wherein the stator coil has a parallel delta winding configuration, each delta winding portion is connected to a plurality of inverter devices, and the inverter devices are configured to independently supply excitation voltage to each delta winding portion.

10. A control system for a rotating electric machine as claimed in claim 9, characterized in that a converter circuit corresponding to each of said inverter devices is provided, and power is supplied to said converter circuits from an independent system power supply.

11. A rotating electric machine comprising: a rotor fixed to a rotating shaft; a stator core arranged on the outer periphery of the rotor, with a plurality of slots formed in the circumferential direction; and a stator coil formed of a plurality of U-shaped coil pieces made of rectangular wire inserted into the slots from the lead-out side or the opposite lead-out side in the direction of the rotating shaft; wherein a bobbin having a slot hole for accommodating m pieces of the rectangular wire in the radial direction is arranged in each of the slots; and the coil pieces inserted from the lead-out side in the direction of the rotating shaft are: a) prepared as a group of the coil pieces formed by two straight portions accommodated in the slot holes spaced five slots apart in the circumferential direction and coil end portions extending outward in the direction of the rotating shaft from the straight portions and extending in the direction of the rotating shaft and in the circumferential direction to connect the two straight portions, the group including m-1 types of central coil pieces, m-1 types of outer coil pieces whose coil end portions are bent so as to bend radially outward, and m-1 types of inner coil pieces whose coil end portions are bent so as to bend radially inward; b) starting from the slot hole which is the starting point of the inner coil piece, m-1 types of the inner coil pieces are stacked in the radial direction over the entire circumferential direction such that the connection portions extending in the circumferential direction of the coil end portions of the inner coil pieces are stacked in the radial direction; c) starting from the slot hole which is located four slots circumferentially away from the starting point of the inner coil piece, m-1 types of the outer coil pieces are stacked in the circumferential direction over the entire circumferential direction such that the connection portions extending in the circumferential direction of the coil end portions of the outer coil pieces are stacked in the rotation axis direction; d) starting from a position two slots circumferentially away from the starting point, m-1 types of the central coil pieces are stacked in the circumferential direction over the entire circumferential direction such that the connection portions extending in the circumferential direction of the coil end portions of the central coil pieces are aligned in the radial direction; and the coil pieces to be inserted from the opposite end in the rotation axis direction are e) preparing m types of central coil pieces, m types of outer coil pieces whose coil end portions are bent so as to be bent radially outward, and m types of inner coil pieces whose coil end portions are bent so as to be bent radially inward, as groups of coil pieces each formed by two straight portions received in the slot holes spaced five slots apart in the circumferential direction and coil end portions formed so as to extend outward in the direction of the rotation axis from the straight portions and extending in the direction of the rotation axis and in the circumferential direction to connect the two straight portions;f) starting from the slot hole which serves as the starting point of the inner coil piece, m-1 types of the inner coil pieces are stacked all around in the circumferential direction such that connection portions extending in the circumferential direction of the coil end portions of the inner coil pieces are stacked in the radial direction; g) starting from the slot hole which is four slots circumferentially away from the starting point of the inner coil piece, m-1 types of the outer coil pieces are stacked all around in the circumferential direction such that connection portions extending in the circumferential direction of the coil end portions of the outer coil pieces are stacked in the rotation axis direction; h) starting from a position two slots circumferentially away from the starting point, m-1 types of the central coil pieces are stacked all around in the circumferential direction such that connection portions extending in the circumferential direction of the coil end portions of the central coil pieces are aligned in the radial direction; and a concentrically wound coil is formed by connecting the set of coil pieces inserted into the slot of the stator core from the lead side and the set of coil pieces inserted from the opposite lead side within the slot hole.

12. A method for manufacturing a stator for a rotating electric machine, comprising the steps of: preparing a plurality of lead wires each having a shape obtained by bending a straight rectangular wire into a crank shape; and, at the lead-out side in the direction of the rotation axis, before performing step b), placing one lead piece in the innermost slot hole on the starting point side that accommodates the inner coil pieces, and placing one lead piece in the outermost slot on the other side; before performing step c), placing one lead piece in the innermost slot hole on the starting point side that accommodates the outer coil pieces, and placing one lead piece in the outermost slot on the other side; and before performing step d), placing one lead piece in the innermost slot on one side of the slots that accommodate the central coil pieces, and placing one lead piece in the outermost slot on the other side.

13. A manufacturing method for a stator in a rotating electric machine as recited in claim 12, characterized in that a convex portion or a concave portion is formed on the open ends of the inner coil piece, the inner coil piece, the central coil piece and the lead piece on the lead side, a concave portion or a convex portion corresponding to the lead side is formed on the open ends of the inner coil piece, the inner coil piece and the central coil piece on the anti-lead side, and the convex portions and concave portions of the lead side and anti-lead side coil pieces are fitted within the slot holes of the bobbin, thereby electrically connecting the coil pieces.

14. A method for manufacturing a stator for a rotating electric machine according to claim 13, characterized in that the order of execution of the assembly step b) and the assembly step c) can be reversed, and the order of execution of the assembly step f) and the assembly step g) can be reversed.

15. A manufacturing method for a stator in a rotating electric machine as recited in claim 14, characterized in that the circumferential length of the coil ends of the inner coil pieces is shorter and the circumferential length of the coil ends of the outer coil pieces is longer than the circumferential length of the coil end portion of the central coil piece, the central coil piece on the output side and the central coil piece on the opposite output side are connected, the inner coil piece on the output side and the outer coil piece on the opposite output side are connected, and the outer coil piece on the output side and the inner coil piece on the opposite output side are connected, thereby making the circumferential lengths of the concentric parts uniform.

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