Stator of three-phase ac motor

Abstract

Provided is a stator of a three-phase AC motor, the stator comprising: a stator core; a plurality of slots arranged in the circumferential direction of the stator core; coils accommodated in respective slots and each having two lead wires led out from both ends of a winding wound so as to form a ring; and crossover wires connecting, in each coil group composed of the coils of the same phase, one of the two lead wires of a coil and one of the two lead wires of another coil. The coil group of the same phase is composed of a positive-direction coil group and a negative-direction coil group. In the positive-direction coil group of the same phase, the coils are connected in series by the crossover wires in the arrangement order of the coils of this phase along the circumferential direction. In the negative-direction coil group of the same phase, the coils are connected in series by the crossover wires in the arrangement order of the coils of this phase along a direction opposite to the circumferential direction. The coil group of a second phase is disposed at a position shifted by 120 degrees in the circumferential direction from the coil group of a first phase, and the coil group of a third phase is disposed at a position shifted by 240 degrees in the circumferential direction from the coil group of the first phase. In the coil group of the same phase, the slots from which the lead wires electrically connected by the respective crossover wires for the positive-direction coil group are led out and the slots from which the lead wires connected by the respective crossover wires for the negative-direction coil group are led out are arranged in line symmetry with respect to a shared line symmetry axis.

Description

Stator of a three-phase AC motor

[0001] The present disclosure relates to a stator of a three-phase AC motor.

[0002] There is known a three-phase AC motor having a stator in which a star-connected (Y-connected) three-phase coil group is arranged. In the coil group, a plurality of coils are connected by jumper wires.

[0003] Japanese Patent Application Laid-Open No. 2014-073047, Japanese Patent Application Laid-Open No. 2010-246353, International Publication No. 2019 / 208088, International Publication No. 2007 / 052385

[0004] Among three-phase AC motors having fractional slots in which the value obtained by dividing the number of slots by the number of poles is an irreducible fraction, such as a three-phase supply motor with 10 poles and 12 slots or 14 poles and 12 slots, in a three-phase AC motor where the number of pole pairs ( = number of poles ÷ 2) is odd, when the stator coils are double-star connected and a coil arrangement having rotational symmetry is made, a large potential difference of about the same magnitude as the terminal voltage appears between adjacent coils. As a result, corona discharge is likely to occur between adjacent coils, and insulation breakdown is also likely to occur. Therefore, in the stator of a three-phase AC motor, it is desired to enhance the insulation between adjacent coils.

[0005] According to one aspect of the present disclosure, a stator core is provided, a plurality of slots arranged circumferentially around the stator core is provided, 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 is provided, 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 is provided for the first, second, and third phases of a three-phase AC motor, and the group of coils of the same phase consists of a positive-direction coil group and a negative-direction coil group. In a group of positive coils of the same phase, the coils are electrically connected in series by jumper wires in the order of their arrangement along the circumferential direction, with one of the two lead wires of the coil at one end of the circumferentially arranged coils serving as the phase terminal, and one of the two lead wires of the coil at the other end of the circumferentially arranged coils serving as the neutral point terminal. In a group of negative coils of the same phase, the coils are electrically connected in series by jumper wires in the order of their arrangement along the opposite direction to the circumferential direction, with one of the two lead wires of the coil at one end of the coils arranged in the opposite direction to the circumferential direction serving as the phase terminal, and one of the two lead wires of the coil at the other end of the coils arranged in the opposite direction serving as the neutral point terminal. A group of second-phase coils is positioned 120 degrees circumferentially from the group of first-phase coils, and a group of third-phase coils is positioned 240 degrees circumferentially from the group of first-phase coils. A stator for a three-phase AC motor, in which, within a group of coils of the same phase, the slots from which lead wires electrically connected by each jumper wire for the positive coil group are drawn, and the slots from which lead wires electrically connected by each jumper wire for the negative coil group are drawn, are arranged symmetrically with respect to a common axis of symmetry.

[0006] It is a perspective view showing the structure of the stator of a 12-slot three-phase AC motor that generates magnetism with an odd number of pole pairs according to an embodiment of the present disclosure. It is a perspective view showing the structure of the winding. It is a perspective view showing the structure of a coil, showing a coil wound with a winding in the first winding direction. It is a perspective view showing the structure of a coil, showing a coil wound with a winding in the second winding direction. It is a cross-sectional view showing the stator shown in FIG. 1. It is an exploded perspective view showing the U-phase coil group arranged in the stator shown in FIG. 1. It is a cross-sectional view showing the U-phase coil group arranged in the stator shown in FIG. 1. It is an exploded perspective view showing the V-phase coil group arranged in the stator shown in FIG. 1. It is a cross-sectional view showing the V-phase coil group arranged in the stator shown in FIG. 1. It is an exploded perspective view showing the W-phase coil group arranged in the stator shown in FIG. 1. It is a cross-sectional view showing the W-phase coil group arranged in the stator shown in FIG. 1. It is a cross-sectional view explaining a set of slots having a common line symmetry axis in the stator. It is a cross-sectional view explaining a set of slots having rotational symmetry in the stator. It is a cross-sectional view showing a set of U-phase slots having a common line symmetry axis in an embodiment of the present disclosure. It is a cross-sectional view showing a set of V-phase slots having a common line symmetry axis in an embodiment of the present disclosure. It is a cross-sectional view showing a set of W-phase slots having a common line symmetry axis in an embodiment of the present disclosure. It is a diagram 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. It is a diagram 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. It is a diagram showing the star-connected three-phase coil group in the stator shown in FIG. 1. It is a perspective view showing the potential difference between the adjacent coils Ub1 and Va2, the potential difference between the adjacent coils Ub2 and Wa1, and the potential difference between the adjacent coils Wa2 and Vb1 in the stator shown in FIG. 1. It is an exploded perspective view showing the structure of the stator of a 12-slot three-phase AC motor that generates magnetism with an odd number of pole pairs according to the prior art. It is a cross-sectional view showing the U-phase coil group arranged in the stator shown in FIG. 15. It is a cross-sectional view showing the V-phase coil group arranged in the stator shown in FIG. 15. It is an exploded perspective view showing the W-phase coil group arranged in the stator shown in FIG. 15.

[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 conventions 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 same shape to form a closed loop. A coil can be divided into a portion housed in a stator slot 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". The number of slots that a coil housed in a stator slot spans may be called the "coil pitch". A "jumper wire" is a conductive component that connects the coil ends of two different coils. "Line symmetry" may be called "mirror symmetry", "mirror reflection", or "inversion". Also, "electrically connected" may be written as "short-circuited", "connected", or simply "connected". Furthermore, in the following explanation, the effective value of the potential difference between each terminal of UVW is 400V. rms However, 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. As will be described in detail later, a portion of the coil is housed in a slot provided in the stator core. 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.

[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. To identify the 12 slots S, each slot is assigned a slot identification number, for example, 1 to 12, along the circumferential direction. When one direction along the circumference of the stator core A where the multiple slots S are arranged is defined as the "circumferential direction," the direction opposite to that direction is referred to as the "opposite direction to the circumferential direction." For example, if the "circumferential direction" of the stator core A is clockwise, then the "opposite direction to the circumferential direction" of the stator core A is counterclockwise. Also, for example, if the "circumferential direction" of the stator core A is counterclockwise, then the "opposite direction to the circumferential direction" of the stator core A is clockwise.

[0017] When an embodiment of this disclosure is applied to the stator 100 of a three-phase AC motor with an odd number of pole pairs, the coil group of each phase consists of a positive coil group and a negative coil group having a polarity reversal relationship. For convenience, these are named "positive coil group" and "negative coil group," but other names may be used. For example, they may be named "positive coil group" and "negative coil group," or "first coil group" and "second coil group," respectively. In the positive coil group, the coils are electrically connected in series by jumper wires in the order of their arrangement along the circumferential direction of the coils of that phase. In the negative coil group, the coils are electrically connected in series by jumper wires in the order of their arrangement along the opposite direction to the circumferential direction of the coils of that phase. For example, when the slot identification numbers assigned to each slot to identify the slots S arranged in the circumferential direction of the stator core are 1 to n (where n is a positive integer, and in the embodiment illustrated in this disclosure, n is, for example, 12), the "circumferential arrangement of the coils" refers to the arrangement of the slots S arranged in ascending order of slot identification numbers 1 to n, and the "reverse circumferential arrangement of the coils" refers to the arrangement of the slots S arranged in descending order of slot identification numbers n to 1.

[0018] The U-phase coil group consists of coil Ua2, coil Ua1, coil Ub2, and coil Ub1. Coils Ua2 and Ua1 constitute, for example, a positive-direction coil group. One end terminal of the U-phase positive-direction coil group is set as the "U-phase terminal UA," and the other end terminal is set as the "neutral point terminal NUA." Coils Ub2 and Ub1 constitute, for example, a negative-direction coil group. One end terminal of the U-phase negative-direction coil group is set as the "U-phase terminal UB," and the other end terminal is set as the "neutral point terminal NUB." In the positive-direction coil group, coils Ua2 and Ua1, which are arranged adjacent to each other, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils Ua2 and Ua1 is coil 60P, and the other is coil 60N. In the negative-direction coil group, coils Ub2 and Ub1, which are arranged adjacent to each other, have their winding directions reversed (opposite directions). That is, one of coils Ub2 and Ub1 is coil 60P, and the other is coil 60N. The U-phase terminals UA and UB are electrically connected to the U-phase power lines from the outside of the motor.

[0019] Coil Ua2 is housed in slots S of slot identification numbers 12 and 1. In coil Ua2, 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 Ua1 is housed in slots S of slot identification numbers 1 and 2. In coil Ua1, 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 Ub2 is housed in slots S of slot identification numbers 6 and 7. In coil Ub2, 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 Ub1 is housed in slots S of slot identification numbers 7 and 8. In coil Ub1, 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.

[0020] In the U-phase positive coil group, the lead wire (+) drawn from slot S of slot identification number 1 of coil Ua2 is defined as the terminal UA of the U-phase. The lead wire (-) drawn from slot S of slot identification number 12 of coil Ua2 and the lead wire (+) drawn from slot S of slot identification number 1 of coil Ua1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 2 of coil Ua1 is defined as the neutral terminal NUA.

[0021] In the negative coil group of the U phase, the lead wire (+) drawn from slot S of slot identification number 6 of coil Ub2 is defined as the terminal UB of the U phase. The lead wire (-) drawn from slot S of slot identification number 7 of coil Ub2 and the lead wire (+) drawn from slot S of slot identification number 8 of coil Ub1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 8 of coil Ub1 is defined as the neutral terminal NUB.

[0022] By providing jumper wires as described above in each of the U-phase positive coil group and negative coil group, in the U-phase coil group, coil Ua2 having the U-phase terminal UA and coil Ua1 having the neutral point terminal NUA are electrically connected in series, and coil Ub2 having the U-phase terminal UB and coil Ub1 having the neutral point terminal NUB are electrically connected in series.

[0023] The V-phase coil group consists of coil Va2, coil Va1, coil Vb2, and coil Vb1. Coils Va2 and Va1 constitute, for example, a positive-direction coil group. One end terminal of the V-phase positive-direction coil group is set as the "V-phase terminal VA," and the other end terminal is set as the "neutral point terminal NVA." Coils Vb2 and Vb1 constitute, for example, a negative-direction coil group. One end terminal of the V-phase negative-direction coil group is set as the "V-phase terminal VB," and the other end terminal is set as the "neutral point terminal NVB." In the positive-direction coil group, coils Va2 and Va1, which are arranged adjacent to each other, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils Va2 and Va1 is coil 60P, and the other is coil 60N. In the negative-direction coil group, coils Vb2 and Vb1, which are arranged adjacent to each other, have their winding directions reversed (opposite directions). That is, one of coils Vb2 and Vb1 is coil 60P, and the other is coil 60N. The V-phase terminals VA and VB are electrically connected to the V-phase power lines from the outside of the motor.

[0024] Coil Va2 is housed in slots S of slot identification numbers 8 and 9. In coil Va2, 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 Va1 is housed in slots S of slot identification numbers 9 and 10. In coil Va1, 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 Vb2 is housed in slots S of slot identification numbers 2 and 3. In coil Vb2, 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 Vb1 is housed in slots S of slot identification numbers 3 and 4. In coil Vb1, 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.

[0025] In the V-phase positive coil group, the lead wire (+) drawn from slot S of slot identification number 9 of coil Va2 is defined as the V-phase terminal VA. The lead wire (-) drawn from slot S of slot identification number 8 of coil Va2 and the lead wire (+) drawn from slot S of slot identification number 9 of coil Va1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 10 of coil Va1 is defined as the neutral point terminal NVA.

[0026] In the negative coil group of the V phase, the lead wire (+) drawn from slot S of slot identification number 2 of coil Vb2 is defined as the terminal VB of the V phase. The lead wire (-) drawn from slot S of slot identification number 3 of coil Vb2 and the lead wire (+) drawn from slot S of slot identification number 4 of coil Vb1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 3 of coil Vb1 is defined as the terminal NVB of the neutral point.

[0027] By providing jumper wires as described above in each of the positive and negative coil groups of the V phase, in the V phase coil group, coil Va2 having the V phase terminal VA and coil Va1 having the neutral point terminal NVA are electrically connected in series, and coil Vb2 having the V phase terminal VB and coil Vb1 having the neutral point terminal NVB are electrically connected in series.

[0028] The W-phase coil group consists of coils Wa2, Wa1, Wb2, and Wb1. Coils Wa2 and Wa1 constitute, for example, a positive-direction coil group. One end terminal of the W-phase positive-direction coil group is set as the "W-phase terminal WA," and the other end is set as the "neutral point terminal NWA." Coils Wb2 and Wb1 constitute, for example, a negative-direction coil group. One end terminal of the W-phase negative-direction coil group is set as the "W-phase terminal WB," and the other end is set as the "neutral point terminal NWB." In the positive-direction coil group, coils Wa2 and Wa1, which are arranged adjacent to each other, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils Wa2 and Wa1 is coil 60P, and the other is coil 60N. In the negative-direction coil group, coils Wb2 and Wb1, which are arranged adjacent to each other, have their winding directions reversed (opposite directions). That is, one of coils Wb2 and Wb1 is coil 60P, and the other is coil 60N. W-phase power lines are electrically connected from the outside of the motor to terminals WA and WB of the W-phase.

[0029] Coil Wa2 is housed in slots S of slot identification numbers 4 and 5. In coil Wa2, 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 Wa1 is housed in slots S of slot identification numbers 5 and 6. In coil Wa1, 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 Wb2 is housed in slots S of slot identification numbers 10 and 11. In coil Wb2, 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 Wb1 is housed in slots S of slot identification numbers 11 and 12. In coil Wb1, 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.

[0030] In the W-phase positive coil group, the lead wire (+) drawn from slot S of slot identification number 5 of coil Wa2 is defined as the W-phase terminal WA. The lead wire (-) drawn from slot S of slot identification number 4 of coil Wa2 and the lead wire (+) drawn from slot S of slot identification number 5 of coil Wa1 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 6 of coil Wa1 is defined as the neutral point terminal NWA.

[0031] In the W-phase negative coil group, the lead wire (+) drawn from slot S of slot identification number 10 of coil Wb2 is designated as the W-phase terminal WB. The lead wire (-) drawn from slot S of slot identification number 11 of coil Wb2 and the lead wire (+) drawn from slot S of slot identification number 12 of coil Wb1 are electrically connected by jumper wires. The lead wire (-) drawn from slot S of slot identification number 11 of coil Wb1 is designated as the neutral point terminal NWB.

[0032] By providing jumper wires as described above in each of the positive and negative coil groups of the W phase, in the W phase coil group, coil Wa2 having the W phase terminal WA and coil Wa1 having the neutral point terminal NWA are electrically connected in series, and coil Wb2 having the W phase terminal WB and coil Wb1 having the neutral point terminal NWB are electrically connected in series.

[0033] Since the neutral terminals NUA, NUB, NVA, NVB, NWA, and NWB 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). In the U-phase coil group, the positive coil group, in which coils Ua2 and Ua1 are connected in series in a straight line, and the negative coil group, in which coils Ub2 and Ub1 are connected in series in a straight line, are electrically connected via the neutral terminals NUA and NUB. In the V-phase coil group, the positive coil group, in which coils Va2 and Va1 are connected in series in a straight line, and the negative coil group, in which coils Vb2 and Vb1 are connected in series in a straight line, are electrically connected via the neutral terminals NVA and NVB. In the W-phase coil group, the positive-direction coil group, in which coils Wa2 and Wa1 are connected in series in a straight line, and the negative-direction coil group, in which coils Wb2 and Wb1 are connected in series in a straight line, are electrically connected via the neutral point terminals NVA and NVB. In other words, two star configurations are formed: a star connection for the positive-direction coil group and a star connection for the negative-direction coil group. This type of connection is called a "double star connection".

[0034] <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.

[0035] (1) The magnetic flux generated in the stator core is an odd function with an odd period in the circumferential direction of the stator.

[0036] (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.

[0037]

[0038] Here, f(r, θ, z) is a three-dimensional vector of magnetic flux density in polar coordinates (r, θ, z). r is the radial distance from the stator center, and the direction extending radially from the center is considered positive. 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. Furthermore, 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.

[0039] 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.

[0040] 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 each coil lead wire of coils Ua1 to Ub2 in Figures 4A and 4B, coils Va1 to Vb2 in Figures 5A and 5B, and coils Wa1 to Wb2 in Figures 6A and 6B, as shown in Figures 3 to 6B. As a result, the 12-slot stator 100 of this disclosure can generate magnetism with an odd number of pole pairs, and the stator 100 can be 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 100 of the embodiments of this disclosure 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.

[0041] 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.

[0042] In Figure 1, the stator 100, which has 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.

[0043] <Connection between coils by jumper wires in embodiments of this disclosure> One of the features of embodiments of this disclosure is that, in groups of coils of the same phase, in the positive direction group, 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, and in the negative direction group, the coils are electrically connected in series by jumper wires in the order in which they are arranged along the opposite direction to the circumferential direction of the coils of that phase. That is, in groups of coils of the same phase, in the positive direction group, 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 (omitting) any specific coils of that phase. Also, in groups of coils of the same phase, in the negative direction group, the coils are electrically connected by jumper wires in the order in which they are arranged along the opposite direction to the circumferential direction of the coils of that phase, without skipping over (omitting) any specific coils of that phase.

[0044] As shown in Figures 1, 3, 4A, and 4B, in the U-phase coil group, the positive coil group is arranged circumferentially in the order of coil Ua2, coil Ua1, etc., and the negative coil group is arranged in the opposite direction to the circumferential direction in the order of coil Ub2, coil Ub1, etc. Therefore, in the U-phase coil group, coil Ua2 and coil Ua1 are electrically connected by jumper wires, and coil Ub2 and coil Ub1 are electrically connected by jumper wires.

[0045] As shown in Figures 1, 3, 5A, and 5B, in the V-phase coil group, the positive coil group is arranged circumferentially in the order of coil Va2, coil Va1, etc., and the negative coil group is arranged in the opposite direction to the circumferential direction in the order of coil Vb2, coil Vb1, etc. Therefore, in the U-phase coil group, coil Va2 and coil Va1 are electrically connected by jumper wires, and coil Vb2 and coil Vb1 are electrically connected by jumper wires.

[0046] As shown in Figures 1, 3, 6A, and 6B, in the W-phase coil group, the positive-direction coil group is arranged circumferentially in the order of coil Wa2, coil Wa1, etc., while the negative-direction coil group is arranged in the opposite direction to the circumferential direction in the order of coil Wb2, coil Wb1, etc. Therefore, in the W-phase coil group, coil Wa2 and coil Wa1 are electrically connected by jumper wires, and coil Wb2 and coil Wb1 are electrically connected by jumper wires.

[0047] <Arrangement of Phase Terminals and Neutral Point Terminals in Embodiments of the Disclosure> One of the embodiments of the Disclosure is that the coils from which the terminals of each phase are drawn out and the coil from which the terminal of the neutral point N is drawn out are alternately arranged at positions offset by 60 degrees from each other in the circumferential direction of the stator 100. That is, the coils are arranged in the following order, with each coil offset by 60 degrees in the circumferential direction: coil Ua2 from which the terminal UA of the U-phase coil group is drawn out, coil Vb1 from which the neutral point terminal NVB of the V-phase coil group is drawn out, coil Wa2 from which the terminal WA of the W-phase coil group is drawn out, coil Ub1 from which the neutral point terminal NUB of the U-phase coil group is drawn out, coil Va2 from which the terminal VA of the V-phase coil group is drawn out, and coil Wb1 from which the neutral point terminal NWB of the W-phase coil group is drawn out. In other words, the spacing between the terminals of the neutral point on the stator core A alternates between 30 degrees and 90 degrees in the circumferential direction. Specifically, the spacing between neutral point terminal NUA and neutral point NUB is 30 degrees, the spacing between neutral point terminal NUB and neutral point NWA is 90 degrees, the spacing between neutral point terminal NWA and neutral point NUB is 30 degrees, the spacing between neutral point terminal NUB and neutral point NVA is 90 degrees, the spacing between neutral point terminal NVA and neutral point NWB is 30 degrees, and the spacing between neutral point terminal NWB and neutral point NUA is 90 degrees.

[0048] <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.

[0049] 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.

[0050] <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.

[0051] 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 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).

[0052] <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 of the jumper wires for the positive coil group are drawn, and the slots from which lead wires electrically connected by each of the jumper wires for the negative coil group are drawn, are arranged symmetrically with respect to a common axis of symmetry.

[0053] Figure 8 is a cross-sectional view showing a set of U-phase slots having a common axis of symmetry in an embodiment of the present disclosure. The jumper wires of the U-phase coil group are arranged symmetrically with respect to the common axis of symmetry LU. Specifically, as shown in Figure 8, 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, while 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.

[0054] Figure 9 is a cross-sectional view showing a set of V-phase slots having a common axis of symmetry in an embodiment of the present disclosure. As shown in Figure 9, 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 8 and slot S of slot identification number 4, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LV, while slot S of slot identification number 9 and slot S of slot identification number 3, from which the lead wires electrically connected to the jumper wires are drawn, are arranged symmetrically with respect to the axis of symmetry LV.

[0055] Figure 10 is a cross-sectional view showing a set of W-phase slots having a common axis of symmetry in an embodiment of the present disclosure. As shown in Figure 10, 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 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 the axis of symmetry LW, while 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.

[0056] <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 "".

[0057] Figure 11 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 reference point for potential, and its potential is denoted as "0V".

[0058] In a stator with a star-connected three-phase coil group, the effective value V is the potential difference between each terminal of U, V, and W to which a sinusoidal three-phase balanced voltage is applied. e [V rms ] and the peak value E0 [V] of the phase voltage at each terminal. peak The relationship between ] and is given by Equation 2.

[0059]

[0060] Figure 12 illustrates 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.

[0061] In a stator with a star-connected three-phase coil group, the phase voltage E at the U-phase terminal is... u [Vpeak [V] is represented by Equation 3, and the phase voltage E of the V-phase terminal v [V peak ] is represented by Equation 4, and the phase voltage E of the W-phase terminal w [V peak ] is represented 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 E u [V peak ] is 2π / 3 ahead in phase from E w [V peak ] is E u [V peak ] and is assumed to be 2π / 3 behind in phase.

[0062]

[0063]

[0064]

[0065] Fig. 13 is a diagram showing the star-connected three-phase coil groups in the stator shown in Fig. 1.

[0066] In the U-phase coil group, the forward coil group in which coil Ua2 and coil Ua1 are connected in series in a row and the reverse coil group in which coil Ub2 and coil Ub1 are connected in series in a row are electrically connected via the neutral terminals NUA and NUB. In the V-phase coil group, the forward coil group in which coil Va2 and coil Va1 are connected in series in a row and the reverse coil group in which coil Vb2 and coil Vb1 are connected in series in a row are electrically connected via the neutral terminals NVA and NVB. In the W-phase coil group, the forward coil group in which coil Wa2 and coil Wa1 are connected in series in a row and the reverse coil group in which coil Wb2 and coil Wb1 are connected in series in a row are electrically connected via the neutral terminals NWA and NWB. The neutral terminals NUA, NUB, NVA, NVB, NWA, and NWB constitute the neutral point N of the coils arranged in the stator of the three-phase AC motor. Therefore, a double-star connection is formed by the star connection related to the forward coil group and the star connection related to the reverse coil group.

[0067] 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.

[0068] For example, in the forward-direction coil group of the U-phase coil group, the potentials of the lead wires of coil Ua1 and coil Ua2 are set in order from the one closest to the neutral point N to E ua1 , E ua2 Let's assume that in the negative direction coil group of the U-phase coil group, the potentials of the lead wires of coil Ub1 and coil Ub2 are set in order from the one closest to the neutral point N to E. ub1 , E ub2 Let E ua1 = E ub1 = E u / 2, E ua2 = E ub2 = 2E u It becomes / 2. E u This is expressed by equation 3.

[0069] Furthermore, in the forward coil group of the V-phase coil group, the potentials of the lead wires of coil Va1 and coil Va2 are set in order from the one closest to the neutral point N to E va1 , E va2 Let's assume that in the negative direction coil group of the V-phase coil group, the potentials of the lead wires of coil Vb1 and coil Vb2 are set in order from the one closest to the neutral point N to E. vb1 , E vb2 Let E va1 = E vb1 = E v / 2, E va2 = E vb2 = 2E v It becomes / 2. E v This is expressed by equation 4.

[0070] Furthermore, in the forward-direction coil group of the W-phase coil group, the potentials of the lead wires of coil Wa1 and coil Wa2 are set in order from the one closest to the neutral point N to E wa1 , E wa2 Let's assume that in the negative direction coil group of the W-phase coil group, the potentials of the lead wires of coil Wb1 and coil Wb2 are set in order from the one closest to the neutral point N to E. wb1 , Ewb2 Let E wa1 = E wb1 = E w / 2, E wa2 = E wb2 = 2E w It becomes / 2. E w This is expressed by equation 5.

[0071] For example, the potential difference between coil Ub1 and the adjacent coil Va2 can be calculated as follows: In slot S with slot identification number 8, the lead wire (-) of coil Va2 is adjacent to the lead wire (+) of coil Ub1. Therefore, the potential difference between the mutually adjacent coils Ub1 and Va2 is theoretically potential E. ub1 and potential E va1 This is the difference between the two. However, here, the maximum potential difference that can occur between coil Ub1 and coil Va2 is defined as potential E. ub1 and potential E va2 Calculate the difference between the two. Potential E ub1 and potential E va2 The square of the absolute value of the difference between |E ub1 -E va2 | 2 This is calculated according to Equation 6.

[0072]

[0073] Therefore, the peak value of the maximum potential difference that can occur between coil Ub1 and coil Va2 is |E ub1 -E va2 | [V peak This can be expressed as shown in Equation 7.

[0074]

[0075] 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 Ub1 and coil Va2 is |E ub1 -E va2 | [V peak ] is approximately 432 [V] from equation 7. peak The result is calculated as follows, and when converted to an RMS value (multiplied by 1 / √2), it is 306 Vrms.

[0076] Figure 14 is a perspective view showing the potential difference between adjacent coils Ub1 and Va2, between adjacent coils Ub2 and Wa1, and between adjacent coils Wa2 and Vb1 in the stator shown in Figure 1.

[0077] The potential difference between coil Ub2 and coil Wa1, and the potential difference between coil Wa2 and coil Vb1, can be calculated in the same way as the potential difference between coil Ub1 and coil Va2, and their peak value is 432V. peak Therefore, when converted to an effective value, it is 306V rms That is the case.

[0078] <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 15 to 18. The conventional stator shown in Figures 15 to 18 does not have the same line symmetry as the stator according to the embodiment of this disclosure. Figure 15 is an exploded perspective 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 16 is a cross-sectional view showing the U-phase coil group arranged in the stator shown in Figure 15. Figure 17 is a cross-sectional view showing the V-phase coil group arranged in the stator shown in Figure 15. Figure 18 is an exploded perspective view showing the W-phase coil group arranged in the stator shown in Figure 15. Although slot identification numbers are only assigned to the slots S shown in Figures 16 to 18, there is a correspondence between the slots S and coils shown in Figures 15 to 18. In each figure, for the sake of clarity, the leader lines that constitute the terminals of the phases and the leader lines that constitute the terminal of the neutral point are schematically drawn in a state where they are extended outward from the stator.

[0079] 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.

[0080] The U-phase coil group consists of coil Ua20, coil Ua10, coil Ub20, and coil Ub10. Coils Ua20 and Ua10 constitute, for example, a positive-direction coil group. One end terminal of the U-phase positive-direction coil group is set as the "U-phase terminal UA," and the other end is set as the "neutral point terminal NUA." Coils Ub20 and Ub10 constitute, for example, a negative-direction coil group. One end terminal of the U-phase negative-direction coil group is set as the "U-phase terminal UB," and the other end is set as the "neutral point terminal NUB." In the positive-direction coil group, coils Ua20 and Ua10, which are arranged adjacent to each other, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils Ua20 and Ua10 is coil 60P, and the other is coil 60N. In the negative-direction coil group, coils Ub20 and Ub10, which are arranged adjacent to each other, have their winding directions reversed (opposite directions). That is, one of coils Ub20 and Ub10 is coil 60P, and the other is coil 60N. The U-phase terminals UA and UB are electrically connected to the U-phase power lines from the outside of the motor.

[0081] Coil Ua20 is housed in slots S of slot identification numbers 1 and 2. In coil Ua2, 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 Ua10 is housed in slots S of slot identification numbers 12 and 1. In coil Ua10, 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 Ub20 is housed in slots S of slot identification numbers 6 and 7. In coil Ub20, 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 Ub10 is housed in slots S of slot identification numbers 7 and 8. In coil Ub10, 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.

[0082] In the U-phase positive coil group, the lead wire (+) drawn from slot S of slot identification number 1 of coil Ua20 is defined as the terminal UA of the U-phase. The lead wire (-) drawn from slot S of slot identification number 2 of coil Ua20 and the lead wire (+) drawn from slot S of slot identification number 1 of coil Ua10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 12 of coil Ua10 is defined as the neutral terminal NUA.

[0083] In the negative coil group of the U phase, the lead wire (+) drawn from slot S of slot identification number 6 of coil Ub20 is designated as the terminal UB of the U phase. The lead wire (-) drawn from slot S of slot identification number 7 of coil Ub20 and the lead wire (+) drawn from slot S of slot identification number 8 of coil Ub10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 7 of coil Ub10 is designated as the neutral terminal NUB.

[0084] By providing jumper wires as described above in each of the U-phase positive coil group and negative coil group, in the U-phase coil group, the coil Ua20 having the U-phase terminal UA and the coil Ua10 having the neutral point terminal NUA are electrically connected in series, and the coil Ub20 having the U-phase terminal UB and the coil Ub10 having the neutral point terminal NUB are electrically connected in series.

[0085] The V-phase coil group consists of coil Va20, coil Va10, coil Vb20, and coil Vb10. Coils Va20 and Va10 constitute, for example, a positive-direction coil group. One end terminal of the V-phase positive-direction coil group is set as the "V-phase terminal VA," and the other end is set as the "neutral point terminal NVA." Coils Vb20 and Vb10 constitute, for example, a negative-direction coil group. One end terminal of the V-phase negative-direction coil group is set as the "V-phase terminal VB," and the other end is set as the "neutral point terminal NVB." In the positive-direction coil group, coils Va20 and Va10, which are arranged adjacent to each other, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils Va20 and Va10 is coil 60P, and the other is coil 60N. In the negative-direction coil group, coils Vb20 and Vb10, which are arranged adjacent to each other, have their winding directions reversed (opposite directions). That is, one of coils Vb20 and Vb10 is coil 60P, and the other is coil 60N. The V-phase terminals VA and VB are electrically connected to the V-phase power lines from the outside of the motor.

[0086] Coil Va20 is housed in slots S of slot identification numbers 5 and 6. In coil Va20, 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 Va10 is housed in slots S of slot identification numbers 4 and 5. In coil Va10, 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 Vb20 is housed in slots S of slot identification numbers 10 and 11. In coil Vb20, 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 Vb10 is housed in slots S of slot identification numbers 11 and 12. In coil Vb10, 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.

[0087] In the V-phase positive coil group, the lead wire (+) drawn from slot S of slot identification number 5 of coil Va20 is defined as the V-phase terminal VA. The lead wire (-) drawn from slot S of slot identification number 6 of coil Va20 and the lead wire (+) drawn from slot S of slot identification number 5 of coil Va10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 4 of coil Va10 is defined as the neutral point terminal NVA.

[0088] In the negative coil group of the V phase, the lead wire (+) drawn from slot S of slot identification number 10 of coil Vb20 is designated as the terminal VB of the V phase. The lead wire (-) drawn from slot S of slot identification number 11 of coil Vb20 and the lead wire (+) drawn from slot S of slot identification number 12 of coil Vb10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 11 of coil Vb10 is designated as the terminal NVB of the neutral point.

[0089] By providing jumper wires as described above in each of the positive and negative coil groups of the V phase, in the V phase coil group, coil Va20 having terminal VA of the V phase and coil Va10 having terminal NVA of the neutral point are electrically connected in series, and coil Vb20 having terminal VB of the V phase and coil Vb10 having terminal NVB of the neutral point are electrically connected in series.

[0090] The W-phase coil group consists of coil Wa20, coil Wa10, coil Wb20, and coil Wb10. Coils Wa20 and Wa10 constitute, for example, a positive-direction coil group. One end terminal of the W-phase positive-direction coil group is set as the "W-phase terminal WA," and the other end is set as the "neutral point terminal NWA." Coils Wb20 and Wb10 constitute, for example, a negative-direction coil group. One end terminal of the W-phase negative-direction coil group is set as the "W-phase terminal WB," and the other end is set as the "neutral point terminal NWB." In the positive-direction coil group, coils Wa20 and Wa10, which are arranged adjacent to each other, have a relationship where the winding direction of their windings is reversed (opposite direction). That is, one of coils Wa20 and Wa10 is coil 60P, and the other is coil 60N. In the negative-direction coil group, coils Wb20 and Wb10, which are arranged adjacent to each other, have their winding directions reversed (opposite directions). That is, one of coils Wb20 and Wb10 is coil 60P, and the other is coil 60N. W-phase power lines are electrically connected to the W-phase terminals WA and WB from the outside of the motor.

[0091] Coil Wa20 is housed in slots S of slot identification numbers 9 and 10. In coil Wa2, 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 Wa10 is housed in slots S of slot identification numbers 8 and 9. In coil Wa10, 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 Wb20 is housed in slots S of slot identification numbers 2 and 3. In coil Wb20, 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 Wb10 is housed in slots S of slot identification numbers 3 and 4. In coil Wb10, 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.

[0092] In the W-phase positive coil group, the lead wire (+) drawn from slot S of slot identification number 9 of coil Wa20 is defined as the W-phase terminal WA. The lead wire (-) drawn from slot S of slot identification number 10 of coil Wa20 and the lead wire (+) drawn from slot S of slot identification number 9 of coil Wa10 are electrically connected by a jumper wire. The lead wire (-) drawn from slot S of slot identification number 3 of coil Wa10 is defined as the neutral point terminal NWA.

[0093] In the W-phase negative coil group, the lead wire (+) drawn from slot S of slot identification number 2 of coil Wb20 is designated as the W-phase terminal WB. The lead wire (-) drawn from slot S of slot identification number 3 of coil Wb20 and the lead wire (+) drawn from slot S of slot identification number 4 of coil Wb10 are electrically connected by jumper wires. The lead wire (-) drawn from slot S of slot identification number 8 of coil Wb10 is designated as the neutral point terminal NWB.

[0094] By providing jumper wires as described above in each of the positive and negative coil groups of the W phase, in the W phase coil group, coil Wa20 having the W phase terminal WA and coil Wa10 having the neutral point terminal NWA are electrically connected in series, and coil Wb20 having the W phase terminal WB and coil Wb10 having the neutral point terminal NWB are electrically connected in series.

[0095] In the U-phase coil group, the positive-direction coil group, in which coil Ua20 and coil Ua10 are connected in series in a single line, and the negative-direction coil group, in which coil Ub20 and coil Ub10 are connected in series in a single line, are electrically connected via the neutral point terminals NUA and NUB. In the V-phase coil group, the positive-direction coil group, in which coil Va20 and coil Va10 are connected in series in a single line, and the negative-direction coil group, in which coil Vb20 and coil Vb10 are connected in series in a single line, are electrically connected via the neutral point terminals NVA and NVB. In the W-phase coil group, the positive-direction coil group, in which coil Wa20 and coil Wa10 are connected in series in a single line, and the negative-direction coil group, in which coil Wb20 and coil Wb10 are connected in series in a single line, are electrically connected via the neutral point terminals NWA and NWB. Therefore, a double star connection is formed by a star connection for the positive coil group and a star connection for the negative coil group.

[0096] <Potential difference between adjacent coils in the prior art> In a stator arranged with a group of three-phase coils connected in a star configuration according to the prior art shown in Figures 14 to 18, the effective value V of the potential difference between each terminal of U, V, and W is e 400V rms In this case, the potential difference between adjacent coils is a maximum of 400V. rms For example, the effective value V of the potential difference between the terminal UB of the U phase and the terminal VB of the V phase. e 400V rms In this case, the potential difference between the adjacent coils Ub20 and Va20 is 400V. rms This is the result.

[0097] <Comparison of Embodiments of the Present Disclosure with the Prior Art> As shown in Figures 14 to 18, in the stator 200 of the prior art, a large potential difference appears, which is about the same as the voltage between the terminals. For example, the effective value Ve of the potential difference between each terminal of U, V, and W is 400V rms In this case, the maximum potential difference between adjacent coils is approximately 400V. rms As a result, corona discharge is more likely to occur between adjacent coils, and dielectric breakdown is also more likely to occur.

[0098] In contrast, in the embodiments of this disclosure, the maximum potential difference between adjacent coils in the stator 100 occurs between each of the coils from which the phase terminals are drawn and the coil from which the neutral point terminal is drawn, as shown in Figure 14. For example, the effective value Ve of the potential difference between each terminal of U, V, and W is 400V rms In this case, the effective value of the maximum potential difference between adjacent coils is approximately 306V. 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.

[0099] 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.

[0100] <Note> The following additional notes are disclosed regarding the above embodiments and modifications.

[0101] (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 group of coils is provided for each of the first, second, and third phases of the three-phase AC motor, and the group of coils of the same phase consists of a positive-direction coil group and a negative-direction coil group. In a group of positive coils of the same phase, the coils are electrically connected in series by jumper wires in the order of their arrangement along the circumferential direction, with one of the two lead wires of the coil at one end of the circumferentially arranged coils serving as the phase terminal, and one of the two lead wires of the coil at the other end of the circumferentially arranged coils serving as the neutral point terminal. In a group of negative coils of the same phase, the coils are electrically connected in series by jumper wires in the order of their arrangement along the opposite direction to the circumferential direction, with one of the two lead wires of the coil at one end of the coils arranged in the opposite direction to the circumferential direction serving as the phase terminal, and one of the two lead wires of the coil at the other end of the coils arranged in the opposite direction serving as the neutral point terminal. A group of second-phase coils is positioned 120 degrees circumferentially from the group of first-phase coils, and a group of third-phase coils is positioned 240 degrees circumferentially from the group of first-phase coils. A stator for a three-phase AC motor, in which, within a group of coils of the same phase, the slots from which lead wires electrically connected by each jumper wire for the positive coil group are drawn, and the slots from which lead wires electrically connected by each jumper wire for the negative coil group 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 in each of the positive coil group and negative coil group within the same phase group, a coil wound in a first winding direction and a coil wound in a second winding direction opposite to the first winding direction are arranged adjacent to each other in the circumferential direction.

[0102] 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 NUA, NUB, NVA, NVB, NWA, NWB Terminals of neutral point UA, UB Terminals of U phase Ua1, Ua2, Ub1, Ub2 U phase coil VA, VB Terminals of V phase Va1, Va2, Vb1, Vb2 V phase coil WA, WB Terminals of W phase Wa1, Wa2, Wb1, Wb2 V phase coil

Claims

1. 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 to form 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, wherein the group of coils is provided for each of the first, second, and third phases of a three-phase AC motor, and the group of coils of the same phase consists of a positive-direction coil group and a negative-direction coil group. In the group of positive coils of the same phase, the coils are electrically connected in series by the jumper wires in the order of their arrangement along the circumferential direction, with one of the two lead wires of the coil located at one end of the circumferentially arranged coils serving as the phase terminal, and one of the two lead wires of the coil located at the other end of the circumferentially arranged coils serving as the neutral point terminal. In the group of negative coils of the same phase, the coils are electrically connected in series by the jumper wires in the order of their arrangement along the opposite direction to the circumferential direction, with one of the two lead wires of the coil located at one end of the coils arranged in the opposite direction to the circumferential direction serving 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 opposite direction serving as the neutral point terminal. A stator for a three-phase AC motor, wherein the coil group of the second phase is positioned at a circumferential angle of 120 degrees from the coil group of the first phase, the coil group of the third phase is positioned at a circumferential angle of 240 degrees from the coil group of the first phase, and in the coil group of the same phase, the slots from which the lead wires electrically connected by each of the jumper wires for the positive coil group are drawn, and the slots from which the lead wires electrically connected by each of the jumper wires for the negative coil group are drawn, are arranged symmetrically with respect to a common axis of symmetry.

2. The stator of a three-phase AC motor according to claim 1, wherein in each of the positive coil group and the negative coil group within the same phase group of coils, 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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