Stator of three-phase ac motor

Abstract

A stator of a three-phase AC motor according to the present invention comprises: a stator core; a plurality of slots arranged in the circumferential direction of the stator core; a coil that is accommodated in each slot and that has two lead wires led out from both ends of a winding wound so as to form a ring; and a crossover wire that, in a coil group composed of coils of the same phase, connects one of the two lead wires of the coil and one of the two lead wires of another coil, wherein a coil group of a second phase is arranged at a position offset from a coil group of a first phase by 120 degrees in the circumferential direction, a coil group of a third phase is arranged at a position offset from the coil group of the first phase by 240 degrees in the circumferential direction, and in a coil group of the same phase, slots from which lead wires respectively connected by the crossover wire are led out are arranged symmetrically about a common axis of symmetry.

Description

Stator of a three-phase AC motor

[0001] This disclosure relates to a stator for a three-phase AC motor.

[0002] A three-phase AC motor is known that has a stator in which a group of three-phase coils arranged in a star connection (Y connection) is positioned. In the coil group, multiple coils are connected by jumper wires.

[0003] Japanese Patent Publication No. 2014-073047, Japanese Patent Publication No. 2010-246353, International Publication No. 2019 / 208088, Japanese Patent Publication No. 2021-023045

[0004] In three-phase AC motors with fractional slots where the value obtained by dividing the number of slots by the number of poles is an irreducible fraction, such as three-phase supply motors with 10 poles and 12 slots or 14 poles and 12 slots, where the number of pole pairs (= number of poles ÷ 2) is odd, the winding arrangement of the same phase lacks rotational symmetry, making it difficult to connect coils in a way that provides rotational symmetry. Furthermore, in connections that do not provide symmetry, potential bias occurs in each coil, resulting in variations in the strength of the potential difference between adjacent coils. As a result, corona discharge is more likely to occur between adjacent coils, and dielectric breakdown is also more likely to occur. Therefore, it is desirable to improve the insulation between adjacent coils in the stator of a three-phase AC motor.

[0005] According to one aspect of the present disclosure, the stator of a three-phase AC motor comprises: a stator core; a plurality of slots arranged circumferentially around the stator core; a plurality of coils housed in each slot, each coil having a conductive winding wound in a loop and two conductive lead wires drawn out from both ends of the winding; and a conductive jumper wire that electrically connects one of the two lead wires of a coil to one of the two lead wires of another coil in a group of coils composed of coils of the same phase, wherein the coil groups are provided for the first, second, and third phases of the three-phase AC motor, with the second phase coil group positioned 120 degrees circumferentially offset from the first phase coil group, and the third phase coil group positioned 240 degrees circumferentially offset from the first phase coil group. In a group of coils, one of the two lead wires of a coil located at one end of the circumferentially arranged coils is designated as the phase terminal, and one of the two lead wires of a coil located at the other end of the circumferentially arranged coils is designated as the neutral point terminal. In a group of coils of the same phase, the slots from which the lead wires electrically connected by each jumper wire are drawn are arranged symmetrically with respect to a common axis of symmetry.

[0006] This is a perspective view showing the structure of a stator of a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to an embodiment of the present disclosure. This is a perspective view showing the structure of a winding. This is a perspective view showing the structure of a coil, showing a coil with a winding wound in a first winding direction. This is a perspective view showing the structure of a coil, showing a coil with a winding wound in a second winding direction. This is a cross-sectional view showing the stator shown in Figure 1. This is an exploded perspective view showing a group of U-phase coils arranged in the stator shown in Figure 1. This is a cross-sectional view showing a group of U-phase coils arranged in the stator shown in Figure 1. This is an exploded perspective view showing a group of V-phase coils arranged in the stator shown in Figure 1. This is a cross-sectional view showing a group of V-phase coils arranged in the stator shown in Figure 1. This is an exploded perspective view showing a group of W-phase coils arranged in the stator shown in Figure 1. This is a cross-sectional view showing a group of W-phase coils arranged in the stator shown in Figure 1. This is a cross-sectional view illustrating a set of slots having a common axis of symmetry in the stator. This is a cross-sectional view illustrating a set of slots having rotational symmetry in the stator. This is a diagram illustrating the relationship between the potential difference between terminals and the phase voltage in a stator where a star-connected group of three-phase coils is arranged. This figure illustrates the relationship between terminal potential difference and phase voltage in a stator with a star-connected three-phase coil group. This figure shows the star-connected three-phase coil group in the stator shown in Figure 1. This figure illustrates the calculation of the potential difference between adjacent coils U4 and W1 in the stator shown in Figure 1. This figure illustrates the calculation of the potential difference between adjacent coils U3 and V2 in the stator shown in Figure 1. This is a perspective view showing the potential difference between adjacent coils U4 and V1, and between adjacent coils U2 and V3 in the stator shown in Figure 1. This figure shows the single star connection of each coil group showing the potential difference between adjacent coils U4 and W1, between adjacent coils V4 and U1, and between adjacent coils W4 and V1 in the stator shown in Figure 1. This is a cross-sectional view showing the structure of a stator of a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to prior art. This is an exploded perspective view showing the U-phase coil group arranged in the stator shown in Figure 14.Figure 14 is an exploded perspective view showing the V-phase coil group arranged in the stator. Figure 14 is an exploded perspective view showing the W-phase coil group arranged in the stator. Figure 14 is a diagram illustrating the calculation of the potential difference between adjacent coils U30 and V40 in the stator. Figure 14 is a perspective view showing the potential difference between adjacent coils in the stator. Figure 14 is a diagram showing the single star connection of each coil group showing the potential difference between adjacent coils in the stator.

[0007] The following describes embodiments of the stator of a three-phase AC motor with reference to the drawings. In the following description, components having the same or similar function are denoted by the same reference numerals. Duplication of these components may be omitted. The drawings have been scaled appropriately for ease of understanding. Furthermore, the embodiments described below do not limit the technical scope or meaning of terms of the invention as described in the claims.

[0008] Furthermore, in the following description, terms are defined in consideration of the function in the embodiments of this disclosure, and may differ depending on the intent or convention of the user or operator. For example, in a three-phase AC motor, "winding" refers to a conductive wire or bundle of wires, such as copper wire, through which current flows. "Coil" refers to a bundle of conductive wires that are connected in the shape of a closed ring and overlap in a single unit. A coil can be divided into a portion housed in a slot in the stator and a portion that is not housed in a slot, but when clearly distinguishing between them, the former may be called the "winding" and the latter the "coil end." A "jumper wire" is a conductive component that connects the coil ends of two different coils. "Line symmetry" may be called "mirror symmetry," "mirror image," or "inversion." Also, "electrically connected" may be written as "connected," "short-circuited," or simply "connected." Furthermore, in the following description, the effective value of the potential difference between each terminal of U, V, and W is 400V. rmsHowever, the numbers listed here are just examples, and other numbers may also be used.

[0009] <Windings and Coils> Before describing the structure of the stator according to the embodiments of this disclosure, we will first describe the windings and coils used in the embodiments of this disclosure.

[0010] Figure 2A is a perspective view showing the structure of a winding. The conductive winding 50 has a conductive wire 52 and a coating 51 for insulating the wire 52 from the outside. The winding 50 may be composed of a single wire 52 or of multiple wires 52 bundled together.

[0011] Figures 2B and 2C are perspective views showing the structure of a coil. Figure 2B shows a coil with windings in a first winding direction, and Figure 2C shows a coil with windings in a second winding direction. A coil consists of bundles of windings 50, each wound in an annular or rectangular shape, connected in the same shape. A group of multiple coils of the same phase is called a "coil group." Coil groups are provided for each of the first phase (e.g., U phase), second phase (e.g., V phase), and third phase (e.g., W phase) of a three-phase AC motor. As will be described in detail later, a portion of the coil is housed in a slot provided in the stator core.

[0012] As shown in Figure 2B, coil 60P has a conductive winding 50 wound in a loop in a first winding direction. As shown in Figure 2C, coil 60N has a conductive winding 50 wound in a loop in a second winding direction. The first winding direction and the second winding direction are inversely related (opposite directions). For example, coil 60P with the winding in the first winding direction may be called a "forward-winding coil" and coil 60N with the winding in the second winding direction may be called a "reverse-winding coil," or coil 60P may be called a "reverse-winding coil" and coil 60N may be called a "forward-winding coil." There is no difference between coil 60P and coil 60N other than the reversed winding direction; for example, the material, thickness, and number of turns of the winding 50 are the same.

[0013] Furthermore, each of the coils 60P and 60N has two conductive lead wires (+) and (-) drawn out from both ends of the winding 50. For convenience, one end (+) of the lead wire is referred to as the "positive end" and the other end (-) as the "negative end," but other names may be used. In a group of coils of the same phase, the positive end of the lead wire of one coil and the negative end of the lead wire of another coil are electrically connected by a conductive jumper wire. The jumper wire, like the winding 50, is a component having a conductive wire material and a coating to insulate this wire material from the outside. Examples of jumper wire components include lead wires with an insulating material covering a cylindrical conductor, and busbars with resin molding applied to copper bars. Other examples include wiring using a printed circuit board, which has a copper foil pattern printed on an insulating substrate and is insulated with solder resist. In the embodiments of this disclosure, as will be described later, two coils of the same phase arranged adjacent to each other in the circumferential direction are one coil 60P with a winding in a first winding direction and the other coil 60N with a winding in a second winding direction opposite to the first winding direction.

[0014] <Stator Structure According to Embodiments of the Disclosure> As an example of embodiments of the disclosure, a stator of a 12-slot three-phase AC motor, which is conventionally used in 10-pole (number of pole pairs = 5) or 14-pole (number of pole pairs = 7) three-phase AC motors, will be described. However, this embodiment may also be applied to stators of three-phase motors with other numbers of poles and slots that generate magnetism with odd-numbered periods.

[0015] The structure of the stator of a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to an embodiment of the present disclosure is shown in Figures 1 and 3 to 6B. Figure 1 is a perspective view showing the structure of the stator of a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to an embodiment of the present disclosure. Figure 3 is a cross-sectional view showing the stator shown in Figure 1. Figure 4A is an exploded perspective view showing the U-phase coil group arranged in the stator shown in Figure 1. Figure 4B is a cross-sectional view showing the U-phase coil group arranged in the stator shown in Figure 1. Figure 5A is an exploded perspective view showing the V-phase coil group arranged in the stator shown in Figure 1. Figure 5B is a cross-sectional view showing the V-phase coil group arranged in the stator shown in Figure 1. Figure 6A is an exploded perspective view showing the W-phase coil group arranged in the stator shown in Figure 1. Figure 6B is a cross-sectional view showing the W-phase coil group arranged in the stator shown in Figure 1. Although only the slot S shown in Figure 3 is labeled with a slot identification number, there is a correspondence between the slot S and coils shown in Figures 1 and 3 to 6B, respectively. In each diagram, for the sake of clarity, the leader lines that constitute the phase terminals and the leader lines that constitute the neutral point terminal are schematically depicted as being extended outward from the stator.

[0016] The stator 100 of a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to an embodiment of the present disclosure comprises a stator core A, slots S, coils, and jumper wires. One direction along the circumference of the stator core A, where the multiple slots S are arranged, is referred to as the "circumferential direction." The "circumferential direction" of the stator core A is either clockwise or counterclockwise, but in this embodiment, as an example, the circumferential direction is set to clockwise. In order to identify the 12 slots S, each slot is assigned a slot identification number, for example, 1 to 12, along the circumferential direction.

[0017] The U-phase coil group consists of coils U4, U3, U2, and U1. Coils U4 and U3, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils U4 and U3 is coil 60P, and the other is coil 60N. Coils U2 and U1, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils U2 and U1 is coil 60P, and the other is coil 60N. One end terminal of the U-phase coil group is set as the "U-phase terminal," and the other end is set as the "neutral point terminal." The U-phase power lines are electrically connected to the U-phase terminal from the outside of the motor.

[0018] Coil U4 is housed in slots S of slot identification numbers 12 and 1. In coil U4, one lead wire (-) is drawn out from the position of slot S of slot identification number 12, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 1. Coil U3 is housed in slots S of slot identification numbers 1 and 2. In coil U3, one lead wire (+) is drawn out from the position of slot S of slot identification number 1, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 2. Coil U2 is housed in slots S of slot identification numbers 6 and 7. In coil U2, one lead wire (+) is drawn out from the position of slot S of slot identification number 6, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 7. Coil U1 is housed in slots S of slot identification numbers 7 and 8. In coil U1, one lead wire (-) is drawn from slot S of slot identification number 7, and the other lead wire (+) is drawn from slot S of slot identification number 8.

[0019] The lead wire (+) drawn from slot S of slot identification number 1 of coil U4 is designated as the terminal of the U phase. The lead wire (-) drawn from slot S of slot identification number 12 of coil U4 and the lead wire (+) drawn from slot S of slot identification number 1 of coil U3 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 2 of coil U3 and the lead wire (+) drawn from slot S of slot identification number 6 of coil U2 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 7 of coil U2 and the lead wire (+) drawn from slot S of slot identification number 8 of coil U1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 7 of coil U1 is designated as the neutral point terminal. By providing this jumper wire, in the U-phase coil group, coil U4, coil U3, coil U2, and coil U1, which has the neutral point N terminal, are electrically connected in series.

[0020] The V-phase coil group consists of coils V4, V3, V2, and V1. Coils V4 and V3, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils V4 and V3 is coil 60P, and the other is coil 60N. Coils V2 and V1, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils V2 and V1 is coil 60P, and the other is coil 60N. One end terminal of the V-phase coil group is set as the "V-phase terminal," and the other end is set as the "neutral point terminal." The V-phase power lines are electrically connected to the V-phase terminal from the outside of the motor.

[0021] Coil V4 is housed in slots S of slot identification numbers 8 and 9. In coil V4, one lead wire (-) is drawn out from the position of slot S of slot identification number 8, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 9. Coil V3 is housed in slots S of slot identification numbers 9 and 10. In coil V3, one lead wire (+) is drawn out from the position of slot S of slot identification number 9, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 10. Coil V2 is housed in slots S of slot identification numbers 2 and 3. In coil V2, one lead wire (+) is drawn out from the position of slot S of slot identification number 2, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 3. Coil V1 is housed in slots S of slot identification numbers 3 and 4. In coil V1, one lead wire (-) is drawn from slot S of slot identification number 3, and the other lead wire (+) is drawn from slot S of slot identification number 4.

[0022] The lead wire (+) drawn from slot S of slot identification number 9 of coil V4 is designated as the terminal of the V phase. The lead wire (-) drawn from slot S of slot identification number 8 of coil V4 and the lead wire (+) drawn from slot S of slot identification number 9 of coil V3 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 10 of coil V3 and the lead wire (+) drawn from slot S of slot identification number 2 of coil V2 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 3 of coil V2 and the lead wire (+) drawn from slot S of slot identification number 4 of coil V1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 3 of coil V1 is designated as the neutral point terminal. By providing this jumper wire, in the V-phase coil group, coil V4, which has the V-phase terminal, coil V3, coil V2, and coil V1, which has the neutral point N terminal, are electrically connected in series.

[0023] The W-phase coil group consists of coils W4, W3, W2, and W1. Coils W4 and W3, which are arranged adjacent to each other in the circumferential direction, have opposite winding directions. That is, one of coils W4 and W3 is coil 60P, and the other is coil 60N. Coils W2 and W1, which are arranged adjacent to each other in the circumferential direction, have opposite winding directions. That is, one of coils W2 and W1 is coil 60P, and the other is coil 60N. One end terminal of the W-phase coil group is set as the "W-phase terminal," and the other end is set as the "neutral point terminal." The W-phase power lines are electrically connected to the W-phase terminals from the outside of the motor.

[0024] Coil W4 is housed in slots S of slot identification numbers 4 and 5. In coil W4, one lead wire (-) is drawn out from the position of slot S of slot identification number 4, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 5. Coil W3 is housed in slots S of slot identification numbers 5 and 6. In coil W3, one lead wire (+) is drawn out from the position of slot S of slot identification number 5, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 6. Coil W2 is housed in slots S of slot identification numbers 10 and 11. In coil W2, one lead wire (+) is drawn out from the position of slot S of slot identification number 10, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 11. Coil W1 is housed in slots S of slot identification numbers 11 and 12. In coil W1, one lead wire (-) is drawn from slot S of slot identification number 11, and the other lead wire (+) is drawn from slot S of slot identification number 12.

[0025] The lead wire (+) drawn from slot S of slot identification number 5 of coil W4 is designated as the W-phase terminal. The lead wire (-) drawn from slot S of slot identification number 4 of coil W4 and the lead wire (+) drawn from slot S of slot identification number 5 of coil W3 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 6 of coil W3 and the lead wire (+) drawn from slot S of slot identification number 10 of coil W2 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 11 of coil W2 and the lead wire (+) drawn from slot S of slot identification number 12 of coil W1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 11 of coil W1 is designated as the neutral point terminal. By providing this jumper wire, in the W-phase coil group, coil W4, coil W3, coil W2, and coil W1, which has the neutral point N terminal, are electrically connected in series.

[0026] Since the terminal of the neutral point N of coil U1, the terminal of the neutral point N of coil V1, and the terminal of the neutral point N of coil W1 are electrically connected, the U-phase coil group, the V-phase coil group, and the W-phase coil group form a star connection (Y connection). The U-phase coil group consists of four U-phase coils connected in series in a row, the V-phase coil group consists of four V-phase coils connected in series in a row, and the W-phase coil group consists of four W-phase coils connected in series in a row. Therefore, the star connection between the U-phase coil group, the V-phase coil group, and the W-phase coil group is sometimes called a "single star connection".

[0027] <Stators that generate magnetism with an odd number of pole pairs> This section explains the characteristics of stators that generate magnetism with an odd number of pole pairs. Stators of electric motors that can be treated as having an odd number of pole pairs (= number of poles ÷ 2), such as 2 poles, 6 poles, 10 poles, or 14 poles, have the characteristics described below.

[0028] (1) The magnetic flux generated in the stator core is an odd function with an odd period in the circumferential direction of the stator.

[0029] (2) Among the characteristics of (1), Equation 1 is a general property of odd-period functions that is not found in electric motors with an even number of pole pairs.

[0030]

[0031] Here, f(r, θ, z) is the three-dimensional vector of magnetic flux density in polar coordinates (r, θ, z). r is the radial distance from the stator center, with positive being the direction extending radially from the center. θ is the angle of deviation from a reference line passing through the center of the stator, and its unit is radians. z is the position on the central axis of the stator. The three-dimensional vector f(r, θ, z) has three components: a radial component in polar coordinates, a circumferential component in polar coordinates, and a component in the central axis direction. From Equation 1, the magnetic flux density vector generated at any point (r, θ, z) on the stator core has the opposite sign to the magnetic flux density vector at a point located 180 degrees opposite the center of the stator in the circumferential direction. In other words, the direction of the magnetic flux density vector generated at a certain point on the stator is reversed in polarity for the magnetic flux density vector at a point 180 degrees opposite that point.

[0032] In order to generate an odd number of pole pairs of magnetism in the stator core and to possess the characteristics of Equation 1, the U-phase coil group, V-phase coil group, and W-phase coil group must be arranged such that the polarity of the magnetic flux density vector generated from a coil placed in an arbitrary slot of the stator is reversed from the polarity of the magnetic flux density vector generated from a coil placed in a slot 180 degrees opposite. Furthermore, since a three-phase AC motor needs to be electrically balanced, the U-phase coil group, V-phase coil group, and W-phase coil group must be arranged so that they are three rotationally symmetrical to each other.

[0033] In the embodiments of this disclosure, in a stator with 12 slots, as an example of a coil arrangement that satisfies Equation 1 and in which the U-phase coil group, V-phase coil group, and W-phase coil group are rotationally symmetrical three times with respect to each other, the positive and negative ends are assigned and connected to the coil lead wires of each coil U1 to U4 in Figures 4A and 4B, each coil V1 to V4 in Figures 5A and 5B, and each coil W1 to W4 in Figures 6A and 6B, as shown in Figures 3 to 6B. As a result, the 12-slot stator of this disclosure can generate magnetism with an odd number of pole pairs and can be mainly used as a 10-pole 12-slot or 14-pole 12-slot stator. Furthermore, although the torque of the motor decreases because the winding coefficient decreases, the 12-slot stator of this embodiment can also be used as a stator for motors with other pole counts, such as 2 poles, 6 poles, etc., where the number of pole pairs (= number of poles ÷ 2) is odd. Generally, the number of poles of a stator is determined by the shape of the rotor of the motor that is combined with the stator, and, if the rotor has permanent magnets, by the magnetic orientation of the permanent magnets.

[0034] In Figures 3 to 6B, two adjacent coils of the same phase have alternating forward-winding and reverse-winding directions. Therefore, during manufacturing, six forward-winding coils and six reverse-winding coils can be pre-arranged alternately in the 12 slots of the stator in the circumferential direction. Later, the positive and negative ends can be assigned to the two pairs of lead wires of the coils, and the symmetrical jumper wire connections in this embodiment can be made. This eliminates the need to identify the phase of each coil when arranging the coils in the stator core due to the symmetry of the jumper wires, thus simplifying manufacturing.

[0035] In Figure 1, a stator with 12 slots is arranged with multiple coils having a slot pitch (number of slots a coil spans) of 1, but this is just one example. Even if the number of slots is not 12, or the slot pitch of the coils is not 1, the embodiments of this disclosure are applicable as long as Equation 1 is satisfied and the conditions that the U-phase coil group, V-phase coil group, and W-phase coil group are rotationally symmetrical to each other three times are met.

[0036] <Connection between coils by jumper wires in embodiments of this disclosure> One of the embodiments of this disclosure is that, in a group of coils of the same phase, the coils are electrically connected in series by jumper wires in the order in which they are arranged along the circumferential direction of the coils of that phase. That is, in a group of coils of the same phase, the coils are electrically connected by jumper wires in the order in which they are arranged along the circumferential direction of the coils of that phase, without skipping over (not passing over) any specific coil of that phase.

[0037] As shown in Figures 1, 3, 4A, and 4B, the U-phase coil group is arranged circumferentially in the order of coil U4, coil U3, coil U2, and coil U1. Therefore, in the U-phase coil group, coil U4 and coil U3 are electrically connected by jumper wires, coil U3 and coil U2 are electrically connected by jumper wires, and coil U2 and coil U1 are electrically connected by jumper wires. For example, it is not possible to skip (overwrite) coil U3 and electrically connect coil U4 and coil U2 with a jumper wire.

[0038] Furthermore, as shown in Figures 1, 3, 5A, and 5B, the V-phase coil group is arranged circumferentially in the order of coil V4, coil V3, coil V2, and coil V1. Therefore, in the V-phase coil group, coil V4 and coil V3 are electrically connected by jumper wires, coil V3 and coil V2 are electrically connected by jumper wires, and coil V2 and coil V1 are electrically connected by jumper wires. For example, it is not done to skip (overwrite) coil V2 and electrically connect coil V3 and coil V1 with jumper wires.

[0039] Furthermore, as shown in Figures 1, 3, 6A, and 6B, the W-phase coil group is arranged circumferentially in the order of coil W4, coil W3, coil W2, and coil W1. Therefore, in the W-phase coil group, coil W4 and coil W3 are electrically connected by jumper wires, coil W3 and coil W2 are electrically connected by jumper wires, and coil W2 and coil W1 are electrically connected by jumper wires. For example, it is not done to electrically connect coil W4 and coil W1 by jumper wires, skipping over (overlapping) coils W3 and W2.

[0040] <Arrangement of Phase Terminals and Neutral Point Terminals in Embodiments of the Present Disclosure> One of the embodiments of the present disclosure is that the slots S from which the terminals of each phase are drawn out and the slots S from which the terminal of the neutral point N is drawn out are alternately arranged at positions that are 60 degrees apart from each other in the circumferential direction of the stator 100. That is, the slots S are arranged in the following order, with each slot S shifted by 60 degrees in the circumferential direction: slot S of slot identification number 1 from which the terminal of the U-phase of the U-phase coil group is drawn out, slot S of slot identification number 3 from which the terminal of the neutral point N of the V-phase coil group is drawn out, slot S of slot identification number 5 from which the terminal of the W-phase of the W-phase coil group is drawn out, slot S of slot identification number 7 from which the terminal of the neutral point N of the U-phase coil group is drawn out, slot S of slot identification number 9 from which the terminal of the V-phase of the V-phase coil group is drawn out, and slot S of slot identification number 11 from which the terminal of the neutral point N of the W-phase coil group is drawn out. If the slot pitch of the coil is not 1, the arrangement of the phase terminals and the neutral point terminal will not be 60 degrees apart.

[0041] <Sets of slots with a common axis of symmetry> We will now explain "sets of slots with a common axis of symmetry." Figure 7A is a cross-sectional view illustrating sets of slots in the stator that have a common axis of symmetry.

[0042] Let M be an integer representing the number of slots in the stator. From the M slots, select several pairs of two slots. In the selected pairs of two slots, if the remainder when the sum of the slot identification numbers of each pair is divided by M is the same, then the relationship "each pair of two slots has a common axis of symmetry" holds true. For example, in the 12 slots shown in Figure 7A, suppose we select a pair of slot identification numbers 12 and 8, a pair of slot identification numbers 1 and 7, and a pair of slot identification numbers 2 and 6. The sum of 12 and 8 is 20, and the remainder when 20 is divided by 12 (=M) is 8. The sum of 1 and 7 is 8, and the remainder when 8 is divided by 12 is 8. The sum of 2 and 5 is 8, and the remainder when 8 is divided by 12 is 8. Therefore, since the remainder is always the same 8 in each set, the set of slots consisting of slot identification numbers 12 and 8, the set of slots consisting of slot identification numbers 1 and 7, and the set of slots consisting of slot identification numbers 2 and 6 share a common axis of symmetry LU. In general, the axis of symmetry is the set of midpoints between two points, and is characterized by the property that the sum of points (sum of vectors) is equal. Furthermore, integers can be classified by the number of periods (remainders) by distinguishing them by the remainder when an integer is divided by the number of slots M.

[0043] <Sets of slots with rotational symmetry> We will now explain "sets of slots with n rotational symmetries". Figure 7B is a cross-sectional view illustrating sets of slots with rotational symmetry in the stator.

[0044] Suppose we select several pairs of two slots from the M available slots. In the selected pairs of two slots, if the remainder when the absolute difference between the slot identification numbers of each pair is divided by M is equal to M / n, then the relationship "each pair of two slots has n rotational symmetries (360 ÷ n degrees of rotational symmetry)" holds true. For example, suppose we select a pair of slots with identification numbers 12 and 6, a pair of slots with identification numbers 1 and 7, and a pair of slots with identification numbers 2 and 8 from the 12 slots shown in Figure 7B. The absolute difference between 12 and 6 is 6, and the remainder when 6 is divided by 12 (=M) is 6. The absolute difference between 1 and 7 is 6, and the remainder when 6 is divided by 12 (=M) is 6. The absolute difference between 2 and 8 is 6, and the remainder when 6 is divided by 12 (=M) is 6. In each set, the remainder is always the same 6 (= 12 ÷ 2), so the set of slots with slot identification numbers 12 and 6, the set of slots with slot identification numbers 1 and 7, and the set of slots with slot identification numbers 2 and 8 have two rotational symmetries (360 ÷ 2 = 180 degrees of rotational symmetry). In general, n-fold rotational symmetry is the set of rotational operations (actions of rotation) of points that coincide when a point is rotated by a certain angle (360 ÷ n degrees) with respect to the center of rotation, and is characterized by the property that the difference between points is constant (the absolute value of the vector difference is constant).

[0045] Note that in Figure 7B, only the U-phase coil group, coils U110 to U140, is shown, and the V-phase and W-phase are omitted. Coil U140 is housed in slots S with slot identification numbers 12 and 1. In coil U140, one lead wire (-) is drawn from the position of slot S with slot identification number 12, and the other lead wire (+) is drawn from the position of slot S with slot identification number 1. Coil U130 is housed in slots S with slot identification numbers 1 and 2. In coil U130, one lead wire (+) is drawn from the position of slot S with slot identification number 1, and the other lead wire (-) is drawn from the position of slot S with slot identification number 2. Coil U120 is housed in slots S with slot identification numbers 6 and 7. In coil U120, one lead wire (+) is drawn from the position of slot S of slot identification number 6, and the other lead wire (-) is drawn from the position of slot S of slot identification number 7. Coil U110 is housed in slot S of slot identification numbers 7 and 8. In coil U110, one lead wire (-) is drawn from the position of slot S of slot identification number 7, and the other lead wire (+) is drawn from the position of slot S of slot identification number 8.

[0046] Figure 7B illustrates the connection of the jumper wires between coils U140, U130, U120, and 110, which have rotational symmetry. Of the two lead wires of coil U130, the lead wire (+) drawn from slot S of slot identification number 1 is designated as the terminal of the U phase. The lead wire (-) drawn from slot S of slot identification number 2 of coil U130 and the lead wire (+) drawn from slot S of slot identification number 1 of coil U140 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 12 of coil U140 and the lead wire (+) drawn from slot S of slot identification number 6 of coil U120 are electrically connected by a jumper wire. The lead wire (-) from slot S of slot identification number 7 of coil U120 and the lead wire (+) from slot S of slot identification number 8 of coil U110 are electrically connected by a jumper wire. The lead wire (-) from slot S of slot identification number 7 of coil U110 is designated as the neutral point terminal. By providing this jumper wire, in the U-phase coil group, coil U130, coil U140, coil U120, and coil U110, which has the neutral point terminal, are connected in series.

[0047] In Figure 7B, the connecting wire (-) from slot S of slot identification number 12 of coil U140 and the connecting wire (+) from slot S of slot identification number 6 of coil U120 spans 180 degrees in the circumferential direction of the stator, resulting in a long connecting wire. In Figure 7B, where the connecting wires are arranged to be rotationally symmetric, only the U-phase coil group is shown. However, the V-phase coil group and the W-phase coil group are also rotationally symmetric to the U-phase coil group, so similarly, there is one long connecting wire in each, resulting in a total of three coil connecting wires that span 180 degrees.

[0048] The 180-degree coil jumper wires are the longest of all the jumper wires connecting the coils in the stator, and the presence of three such wires makes them prone to entanglement, thus posing a manufacturing challenge for the stator. The same applies to stators that generate magnetism with other odd-numbered pole pairs.

[0049] <Set of slots having a common axis of symmetry in embodiments of the present disclosure> One of the embodiments of the present disclosure is characterized in that, in a group of coils of the same phase, the slots from which lead wires electrically connected by each jumper wire are drawn are arranged symmetrically with respect to a common axis of symmetry.

[0050] As shown in Figures 4B and 7A, the jumper wires of the U-phase coil group are arranged symmetrically with respect to a common axis of symmetry LU. Specifically, for the U-phase coil group, slot S of slot identification number 12 and slot S of slot identification number 8, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LU; slot S of slot identification number 1 and slot S of slot identification number 7, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LU; and slot S of slot identification number 2 and slot S of slot identification number 6, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to a common axis of symmetry LU.

[0051] As shown in Figure 5B, the jumper wires of the V-phase coil group are arranged symmetrically with respect to a common axis of symmetry LV. Specifically, for the V-phase coil group, slot S of slot identification number 2 and slot S of slot identification number 10, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LV; slot S of slot identification number 3 and slot S of slot identification number 9, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LV; and slot S of slot identification number 4 and slot S of slot identification number 8, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to a common axis of symmetry LV.

[0052] As shown in Figure 6B, the jumper wires of the W-phase coil group are arranged symmetrically with respect to a common axis of symmetry LW. Specifically, for the W-phase coil group, slot S of slot identification number 6 and slot S of slot identification number 10, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LW; slot S of slot identification number 5 and slot S of slot identification number 11, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LW; and slot S of slot identification number 4 and slot S of slot identification number 12, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to a common axis of symmetry LW.

[0053] <Calculation of Potential Difference Between Adjacent Coils in Embodiments of the Disclosure> In the stator 100 of a three-phase AC motor according to embodiments of the disclosure, the potential difference between adjacent coils in the circumferential direction can be reduced by electrically connecting the coils in the same phase group with jumper wires under the three features described above. The calculation of the potential difference between adjacent coils in the circumferential direction will be explained below with numerical examples. Furthermore, in the following, when the value of the potential difference or voltage refers to the effective value, the unit will be V rms When the potential difference or phase voltage value refers to an instantaneous value or peak value, the unit is V. peak This is used to distinguish between the two. Generally, when the waveform of the potential difference or phase voltage is a sine wave, its RMS value is equal to 1 / √2 times the peak value. When the waveform of the potential difference or phase voltage is a square wave, its RMS value is equal to the peak value. The relationship between the RMS value and the peak value differs depending on the shape of the waveform being dealt with, but the relative magnitudes of the potential difference and phase voltage remain unchanged. Hereafter, the waveform of the potential difference or phase voltage will be treated as a sine wave. That is, the RMS value is 1 / √2 times the peak value. In the figure, the unit of the RMS value is "V rms It is abbreviated as "V" instead of "".

[0054] Figure 8 illustrates the relationship between the potential difference between terminals and the phase voltage in a stator where a star-connected three-phase coil group is arranged. The neutral point N is used as the potential reference, and its potential is denoted as "0V".

[0055] In a stator in which a star-connected three-phase coil group is arranged, the effective value V of the potential difference between each terminal of UVW to which a sine-wave three-phase balanced voltage is applied e [V rms and the peak value E0 [V peak of the phase voltage of each terminal have the relationship of Equation 2.

[0056]

[0057] FIG. 9 is a diagram for explaining the relationship between the potential difference between terminals and the phase voltage in a stator in which a star-connected three-phase coil group is arranged.

[0058] In a stator in which a star-connected three-phase coil group is arranged, the phase voltage E of the U-phase terminal u [V peak is expressed by Equation 3, the phase voltage E of the V-phase terminal v [V peak is expressed by Equation 4, and the phase voltage E of the W-phase terminal w [V peak is expressed by Equation 5. Here, t represents time [s], f [Hz] represents the fundamental frequency of the phase voltage, and j represents the imaginary unit. E v [V peak is 2π / 3 ahead in phase from E u [V peak , and E w [V peak is 2π / 3 behind in phase from E u [V peak .[[]END]]

[0059]

[0060]

[0061] ]END]]

[0062] FIG. 10 is a diagram showing a star-connected three-phase coil group in the stator shown in FIG. 1.

[0063] In the U-phase coil group, coil U4, coil U3, coil U2, and coil U1, which have a U-phase terminal, are electrically connected in series via jumper wires. In the V-phase coil group, coil V4, coil V3, coil V2, and coil V1, which have a V-phase terminal, are electrically connected in series via jumper wires. In the W-phase coil group, coil W4, coil W3, coil W2, and coil W1, which have a W-phase terminal, are electrically connected in series via jumper wires. Since the neutral point N terminal of coil U1, the neutral point N terminal of coil V1, and the neutral point N terminal of coil W1 are electrically connected, the U-phase coil group, the V-phase coil group, and the W-phase coil group form a single star connection.

[0064] Assuming that the impedance of each coil in the stator 100 of a three-phase AC motor is the same, the voltage drop (potential difference drop) across each coil in each phase is equivalent. Under this assumption, if there are n coils in series per phase, the potential at the position of the lead wires between each coil is divided into n equal parts.

[0065] In the U-phase coil group, the potential of the lead wires of each coil is set in order from the one closest to the neutral point N to E u1 , E u2 , E u3 , E u4 Let E u1 = E u / 4, E u2 = 2E u / 4, E u3 =3E u / 4, E u4 = 4E u It becomes / 4. E u This is expressed by equation 3.

[0066] In the V-phase coil group, the potential of the lead wires of each coil is set in order from the one closest to the neutral point N to E v1 , E v2 , E v3 , E v4 Let E v1 = E v / 4, E v2 = 2E v / 4, E v3=3E v / 4, E v4 = 4E v It becomes / 4. E v This is expressed by equation 4.

[0067] In the W-phase coil group, the potential of the lead wires of each coil is set in order from the one closest to the neutral point N to E w1 , E w2 , E w3 , E w4 Let E w1 = E w / 4, E w2 = 2E w / 4, E w3 =3E w / 4, E w4 = 4E w It becomes / 4. E w This is expressed by equation 5.

[0068] Figure 11 illustrates the calculation of the potential difference between adjacent coils U4 and W1 in the stator shown in Figure 1.

[0069] The potential difference between coil U4 and the adjacent coil W1 can be calculated as follows: In slot S with slot identification number 12, the lead wire (+) of coil W1 is adjacent to the lead wire (-) of coil U4. Therefore, the potential difference between the adjacent coils U4 and W1 is theoretically potential E u3 and potential E w1 This is the difference between the two. However, here, the maximum potential difference that can occur between coil U4 and coil W1 is defined as potential E. u4 and potential E w1 Calculate the difference between the two. Potential E u4 and potential E w1 The square of the absolute value of the difference between |E u4 -E w1 | 2 This is calculated according to Equation 6.

[0070]

[0071] Therefore, the maximum potential difference |E| that can occur between coil U4 and coil W1 is... u4 -E w1 | [V peak This can be expressed as shown in Equation 7.

[0072]

[0073] For example, the effective value V of the potential difference between each terminal of UVW e is 400 V rms In the case of, the peak value |E u4 - E w1 | [V peak ] calculated from Equation 7 is approximately 374 [V peak ], and when converted to the effective value (multiplied by 1 / √2), it is 265 V rms is.

[0074] FIG. 12 is a diagram for explaining the calculation of the potential difference between the adjacent coils U3 and V2 in the stator shown in FIG. 1.

[0075] The potential difference between the coil U3 and the adjacent coil V2 is calculated as follows. In the slot S with the slot identification number 2, since the lead wire (-) of the coil U3 is adjacent to the lead wire (+) of the coil V2, the potential difference between the adjacent coils U3 and V2 is the potential E u3 and the potential E v2 The difference between. The absolute value of the difference between the potential E u3 and the potential E v2 The square of |E u3 - E v2 | 2 is calculated according to Equation 8.

[0076]

[0077] Therefore, the peak value |E u3 - E v2 | [V peak ] that can be obtained between the coil U3 and the coil V2 can be expressed as in Equation 9.

[0078]

[0079] From Equation 9, the peak value |E For example, the effective value V of the potential difference between each terminal of UVW e is 400 V rms [[ID=I In the case of, the peak value |E u3 - E v2 | [V ] obtained between the coil U3 and the coil V2 ispeak is about 356 [V from Equation 9 peak and when converted to the effective value, it is 252 Vrms.

[0080] Fig. 13A is a perspective view showing the potential difference between adjacent coils U4 and V1, and the potential difference between adjacent coils U2 and V3 in the stator shown in Fig. 1. In Fig. 13A, the coil group of the W phase is not shown. For example, the effective value V of the potential difference between each terminal of UVW e is 400 V rms In this case, the potential difference between adjacent coils U4 and V1 is about 265 V rms and the potential difference between coils U2 and V3 is about 262 V rms is.

[0081] Fig. 13A is a diagram showing the single-star connection of each coil group showing the potential difference between adjacent coils U4 and W1, the potential difference between adjacent coils V4 and U1, and the potential difference between adjacent coils W4 and V1 in the stator shown in Fig. 1. A lead wire that becomes the terminal of the U phase is drawn out from coil U4, a lead wire that becomes the terminal of the V phase is drawn out from coil V4, and a lead wire that becomes the terminal of the W phase is drawn out from coil W4. Also, lead wires that become the terminals of the neutral point N are drawn out from coils U1, V1, and W1. Therefore, in the stator 100, the potential difference between adjacent coils is the highest between coils U4 and W1, between coils V4 and U1, and between coils W4 and V1. For example, the effective value V of the potential difference between each terminal of UVW e is 400 V, the potential difference between adjacent coils U4 and W1 is at most about 265 V rms and the potential difference between adjacent coils V4 and U1 is at most about 265 V rms and the potential difference between adjacent coils W4 and V1 is at most about 265 V rms is.

[0082] <Conventional Stator Structure> The structure of a stator for a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to conventional technology is shown in Figures 14 to 20. The jumper wires of the conventional stator shown in Figures 14 to 20 do not have the same line symmetry as the stator according to the embodiment of this disclosure. Figure 14 is a cross-sectional view showing the structure of a stator for a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to conventional technology. Figure 15 is an exploded perspective view showing the U-phase coil group arranged in the stator shown in Figure 14. Figure 16 is an exploded perspective view showing the V-phase coil group arranged in the stator shown in Figure 14. Figure 17 is an exploded perspective view showing the W-phase coil group arranged in the stator shown in Figure 14. Although only the slot S shown in Figure 14 is labeled with a slot identification number, there is a correspondence between the slot S and coils shown in Figures 14 to 17. In each figure, for the sake of clarity, the leader wires constituting the phase terminals and the leader wires constituting the neutral point terminal are schematically drawn in a state where they are extended outward from the stator.

[0083] The stator 200 of a 12-slot three-phase AC motor that generates an odd number of pole pairs of magnetism according to conventional technology comprises a stator core A, slots S, coils, and jumper wires. To identify the 12 slots S, each slot is assigned a slot identification number, for example, 1 to 12.

[0084] The U-phase coil group consists of coils U40, U30, U20, and U10. Coils U40 and U30, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their wires is reversed (opposite direction). That is, one of coils U4 and U3 is coil 60P, and the other is coil 60N. Coils U20 and U10, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their wires is reversed (opposite direction). That is, one of coils U20 and U10 is coil 60P, and the other is coil 60N.

[0085] Coil U40 is housed in slots S of slot identification numbers 12 and 1. In coil U40, one lead wire (-) is drawn out from the position of slot S of slot identification number 12, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 1. Coil U30 is housed in slots S of slot identification numbers 1 and 2. In coil U3, one lead wire (+) is drawn out from the position of slot S of slot identification number 1, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 2. Coil U20 is housed in slots S of slot identification numbers 6 and 7. In coil U2, one lead wire (+) is drawn out from the position of slot S of slot identification number 6, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 7. Coil U10 is housed in slots S of slot identification numbers 7 and 8. In coil U1, one lead wire (-) is drawn from slot S of slot identification number 7, and the other lead wire (+) is drawn from slot S of slot identification number 8.

[0086] The lead wire (+) drawn from slot S of slot identification number 1 of coil U40 is the terminal of the U phase. The lead wire (-) drawn from slot S of slot identification number 12 of coil U40 and the lead wire (+) drawn from slot S of slot identification number 1 of coil U30 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 2 of coil U30 and the lead wire (+) drawn from slot S of slot identification number 6 of coil U20 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 7 of coil U20 and the lead wire (+) drawn from slot S of slot identification number 8 of coil U10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 7 of coil U10 is designated as the neutral point terminal. By providing this jumper wire, in the U-phase coil group, coil U40, coil U30, coil U20, and coil U10, which has the neutral point N terminal, are electrically connected in series.

[0087] The V-phase coil group consists of coils V40, V30, V20, and V10. Coils V40 and V30, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their wires is reversed (opposite direction). That is, one of coils V40 and V30 is coil 60P, and the other is coil 60N. Coils V20 and V10, which are arranged adjacent to each other in the circumferential direction, have a relationship where the winding direction of their wires is reversed (opposite direction). That is, one of coils V20 and V10 is coil 60P, and the other is coil 60N.

[0088] Coil V40 is housed in slots S of slot identification numbers 2 and 3. In coil V40, one lead wire (+) is drawn out from the position of slot S of slot identification number 2, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 3. Coil V3 is housed in slots S of slot identification numbers 3 and 4. In coil V30, one lead wire (-) is drawn out from the position of slot S of slot identification number 3, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 4. Coil V20 is housed in slots S of slot identification numbers 8 and 9. In coil V20, one lead wire (-) is drawn out from the position of slot S of slot identification number 8, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 9. Coil V10 is housed in slots S of slot identification numbers 9 and 10. In coil V10, one lead wire (+) is drawn from slot S of slot identification number 9, and the other lead wire (-) is drawn from slot S of slot identification number 10.

[0089] The lead wire (+) drawn from slot S of slot identification number 2 of coil V40 is designated as the terminal of the V phase. The lead wire (-) drawn from slot S of slot identification number 3 of coil V40 and the lead wire (+) drawn from slot S of slot identification number 4 of coil V30 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 3 of coil V30 and the lead wire (+) drawn from slot S of slot identification number 9 of coil V20 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 8 of coil V20 and the lead wire (+) drawn from slot S of slot identification number 9 of coil V10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 10 of coil V10 is designated as the neutral point terminal. By providing this jumper wire, in the V-phase coil group, coil V40, coil V30, coil V20, and coil V10, which has the neutral point N terminal, are electrically connected in series.

[0090] The W-phase coil group consists of coils W40, W30, W20, and W10. Coils W40 and W30, which are arranged adjacent to each other in the circumferential direction, have a relationship in which the winding direction of their wires is reversed (opposite direction). That is, one of coils W40 and W30 is coil 60P, and the other is coil 60N. Coils W20 and W10, which are arranged adjacent to each other in the circumferential direction, have a relationship in which the winding direction of their wires is reversed (opposite direction). That is, one of coils W20 and W10 is coil 60P, and the other is coil 60N.

[0091] Coil W40 is housed in slots S of slot identification numbers 4 and 5. In coil W40, one lead wire (-) is drawn out from the position of slot S of slot identification number 4, and the other lead wire (+) is drawn out from the position of slot S of slot identification number 5. Coil W30 is housed in slots S of slot identification numbers 5 and 6. In coil W30, one lead wire (+) is drawn out from the position of slot S of slot identification number 5, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 6. Coil W20 is housed in slots S of slot identification numbers 10 and 11. In coil W20, one lead wire (+) is drawn out from the position of slot S of slot identification number 10, and the other lead wire (-) is drawn out from the position of slot S of slot identification number 11. Coil W10 is housed in slots S of slot identification numbers 11 and 12. In coil W10, one lead wire (-) is drawn from slot S of slot identification number 11, and the other lead wire (+) is drawn from slot S of slot identification number 12.

[0092] The lead wire (+) drawn from slot S of slot identification number 5 of coil W40 is designated as the W-phase terminal. The lead wire (-) drawn from slot S of slot identification number 4 of coil W40 and the lead wire (+) drawn from slot S of slot identification number 5 of coil W30 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 6 of coil W30 and the lead wire (+) drawn from slot S of slot identification number 10 of coil W20 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 11 of coil W20 and the lead wire (+) drawn from slot S of slot identification number 12 of coil W10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 11 of coil W10 is designated as the neutral point terminal. By providing this jumper wire, in the W-phase coil group, coil W40, coil W30, coil W20, and coil W10, which has the neutral point N terminal, are electrically connected in series.

[0093] Since the terminal of the neutral point N of coil U10, the terminal of the neutral point N of coil V10, and the terminal of the neutral point N of coil W10 are electrically connected, the U-phase coil group, the V-phase coil group, and the W-phase coil group are connected in a star configuration (Y configuration). The U-phase coil group consists of four U-phase coils connected in series in a row, the V-phase coil group consists of four V-phase coils connected in series in a row, and the W-phase coil group consists of four W-phase coils connected in series in a row, so the star configuration between the U-phase coil group, the V-phase coil group, and the W-phase coil group is a single star configuration.

[0094] <Calculation of potential difference between adjacent coils using conventional technology>

[0095] Figure 18 illustrates the calculation of the potential difference between adjacent coils U30 and V40 in the stator shown in Figure 14.

[0096] In a stator in which a group of three-phase coils connected in a star configuration using conventional technology are arranged, the phase voltage E of the U-phase terminal u200 [V peak ] is expressed in equation 10, where the phase voltage E of the V-phase terminal v200 [V peak ] is expressed in equation 11, where the phase voltage E of the W-phase terminal w200 [V peak ] is expressed in Equation 12. Here, t represents time [s], f represents the fundamental frequency [Hz] of the phase voltage, and j represents the imaginary unit. E v200 [V peak ] is E u200 [V peak The phase is 2π / 3 ahead of ], E w200 [V peak ] is E u200 [V peak Assume that the phase is 2π / 3 behind [the other phase].

[0097]

[0098]

[0099]

[0100] In the U-phase coil group, the potential of the lead wires of each coil is set in order from the one closest to the neutral point N to E u10 , E u20 , E u30 , E u40 Let E u10 = E u200 / 4, E u20 = 2E u200 / 4, E u30 =3E u200 / 4, E u40 = 4E u200 It becomes / 4. E u This is represented by equation 10.

[0101] In the V-phase coil group, the potential of the lead wires of each coil is set in order from the one closest to the neutral point N to E v10 , E v20 , E v30 , Ev40 Let E v10 = E v200 / 4, E v20 = 2E v200 / 4, E v30 =3E v200 / 4, E v40 = 4E v200 It becomes / 4. E v This is represented by equation 11.

[0102] In the W-phase coil group, the potential of the lead wires of each coil is set in order from the one closest to the neutral point N to E w10 , E w20 , E w30 , E w40 Let E w10 = E w200 / 4, E w20 = 2E w200 / 4, E w30 =3E w200 / 4, E w40 = 4E w200 It becomes / 4. E w This is expressed by equation 12.

[0103] The potential difference between coil U30 and the adjacent coil V40 can be calculated as follows: In slot S with slot identification number 2, the lead wire (-) of coil U30 is adjacent to the lead wire (+) of coil V40, so the potential difference between the adjacent coils U30 and V40 is potential E u30 and potential E v40 This is the difference between the two. Potential E u30 and potential E v40 The square of the absolute value of the difference between |E u30 -E v40 | 2 This is calculated according to Equation 13.

[0104]

[0105] Therefore, the peak value of the maximum potential difference that can occur between coil U30 and coil V40 is |E u30 -E v40 | [V peak This can be expressed as shown in Equation 14.

[0106]

[0107] For example, the effective value V of the potential difference between each terminal of U, U, and W. e 400V rms In this case, the peak value of the maximum potential difference that can occur between coil U30 and coil V40 is |E u30 -E v40 | [V peak ] is approximately 351 [V] from equation 14. peak It can be calculated as follows, and its effective value is 351V rms That is the case.

[0108] Figure 19 is a perspective view showing the potential difference between adjacent coils U30 and V40 in the stator shown in Figure 14. For example, the effective value V of the potential difference between each terminal of U, V, and W. e 400V rms In this case, the potential difference between the adjacent coils U30 and V40 is approximately 351V. rms That is the case.

[0109] Figure 20 is a perspective view showing the potential difference between adjacent coils in the stator shown in Figure 14. Figure 21 is a diagram showing the single star connection of each coil group, showing the potential difference between adjacent coils in the stator shown in Figure 14.

[0110] Similar to the potential difference between adjacent coils U30 and V40 explained with reference to Figures 14 to 19, the potential differences between other adjacent coils can be calculated as follows: For example, the potential difference between adjacent coils W30 and U20 is 252V. rms The potential difference between adjacent coils U10 and V20, and between adjacent coils V10 and W20, is 153V. rms The potential difference between the adjacent coils W10 and U40 is 265V. rms That is the case.

[0111] <Comparison of Embodiments of the Present Disclosure with the Prior Art> As shown in Figures 20 and 21, in the stator 200 of the prior art, a potential bias occurs in each coil, resulting in asymmetrical strengths and weaknesses in the potential difference between adjacent coils. As a result, corona discharge is likely to occur between adjacent coils, and dielectric breakdown is also likely to occur. Furthermore, for example, the effective value V of the potential difference between each terminal of U, V, and W... e 400V rms In this case, the maximum potential difference between adjacent coils is approximately 351V. rms That is the case.

[0112] In contrast, in the embodiments of this disclosure, the slots S from which the terminals of each phase are drawn and the slot from which the terminal of the neutral point N is drawn are alternately arranged at positions offset by 60 degrees from each other in the circumferential direction of the stator 100. Therefore, the potentials generated in each coil are symmetrical. Also, in the embodiments of this disclosure, as shown in Figures 13A and 13B, the maximum potential difference between adjacent coils in the stator 100 occurs between each of the coils from which the terminals of the phases are drawn and the coil from which the terminal of the neutral point is drawn. For example, the effective value V of the potential difference between each terminal of U, V, and W. e 400V rms In this case, the maximum potential difference between adjacent coils is approximately 265V. rms Thus, the stator 100 according to the embodiment of the present disclosure has a smaller maximum potential difference between adjacent coils than the stator 200 according to the prior art. Therefore, the stator 100 according to the embodiment of the present disclosure is less prone to dielectric breakdown than the stator 200 according to the prior art. Accordingly, according to the embodiment of the present disclosure, the insulation between adjacent coils in the stator of a three-phase AC motor can be improved.

[0113] Although the present disclosure has been described in detail above, this disclosure is not limited to the individual embodiments and modifications described above. These embodiments and modifications can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. Furthermore, these embodiments and modifications can be implemented in combination. For example, the order of operations and processes in the embodiments and modifications described above are shown as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments and modifications described above.

[0114] <Note> The following additional information is disclosed regarding the above embodiments and modifications.

[0115] (Note 1) The motor comprises a stator core, a plurality of slots arranged circumferentially around the stator core, a plurality of coils housed in each slot, each coil having a conductive winding wound in a loop and two conductive lead wires drawn out from both ends of the winding, and a conductive jumper wire that electrically connects one of the two lead wires of one coil to one of the two lead wires of another coil in a group of coils composed of coils of the same phase, the coil groups being provided for the first, second, and third phases of the three-phase AC motor, the second phase coil group being positioned 120 degrees circumferentially from the first phase coil group, and the third phase coil group being positioned 240 degrees circumferentially from the first phase coil group. A stator for a three-phase AC motor, wherein in a group of coils, one of the two lead wires of a coil located at one end of the circumferentially arranged coils is designated as the phase terminal, and one of the two lead wires of a coil located at the other end of the circumferentially arranged coils is designated as the neutral point terminal, and in a group of coils of the same phase, the slots from which the lead wires electrically connected by each jumper wire are drawn are arranged symmetrically with respect to a common axis of symmetry. (Note 2) A stator for a three-phase AC motor as described in Note 1, wherein the slot from which the phase terminals are drawn and the slot from which the neutral point terminal is drawn are located 60 degrees apart in the circumferential direction. (Note 3) A stator for a three-phase AC motor as described in Note 1 or 2, wherein in a group of coils of the same phase, the coils are electrically connected in series by jumper wires in the order in which the coils of that phase are arranged along the circumferential direction. (Note 4) A stator for a three-phase AC motor as described in Note 1 or 2, wherein, in a group of coils of the same phase, a coil with a winding in a first winding direction and a coil with a winding in a second winding direction opposite to the first winding direction are arranged adjacent to each other in the circumferential direction.

[0116] 50 Winding 51 Coating 52 Wire 60P, 60N Coil 100 Stator A Stator core LU, LV, LW Axis of symmetry S Slot N Neutral point U Terminals of U-phase U1, U2, U3, U4 Coils of U-phase V Terminals of V-phase V1, V2, V3, V4 Coils of V-phase W Terminals of W-phase W1, W2, W3, W4 Coils of W-phase

Claims

Stator core and The stator core comprises a plurality of slots arranged in the circumferential direction, A plurality of coils, each housed in the aforementioned slot, wherein each coil has a conductive winding wound in a loop and two conductive lead wires drawn out from both ends of the winding, In a group of coils composed of coils of the same phase, a conductive jumper wire electrically connects one of the two lead wires of one coil to one of the two lead wires of another coil, Equipped with, The coil group is provided for each of the first, second, and third phases of the three-phase AC motor. The coil group of the second phase is positioned at a position shifted 120 degrees in the circumferential direction from the coil group of the first phase, and the coil group of the third phase is positioned at a position shifted 240 degrees in the circumferential direction from the coil group of the first phase. In the coil group, one of the two lead wires of the coil located at one end of the coils arranged in the circumferential direction is designated as the phase terminal, and one of the two lead wires of the coil located at the other end of the coils arranged in the circumferential direction is designated as the neutral point terminal. A stator for a three-phase AC motor, wherein in the group of coils of the same phase, the slots from which the lead wires, electrically connected by each of the jumper wires, are drawn are arranged symmetrically with respect to a common axis of symmetry. 　 The stator of a three-phase AC motor according to claim 1, wherein the slot from which the terminal of the phase is drawn out and the slot from which the terminal of the neutral point is drawn out are located at positions offset by 60 degrees from each other in the circumferential direction. 　 A stator for a three-phase AC motor according to claim 1 or 2, wherein in the group of coils of the same phase, the coils are electrically connected in series by the jumper wires in the order of arrangement along the circumferential direction of the coils of that phase. 　 A stator for a three-phase AC motor according to claim 1 or 2, wherein in the group of coils of the same phase, a coil with a winding in a first winding direction and a coil with a winding in a second winding direction opposite to the first winding direction are arranged adjacent to each other in the circumferential direction.

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