Rotating electric machines

Abstract

A rotating electric machine is equipped with a stator including a stator winding and a stator core having slots. The stator winding includes phase coils, each of which is wound in a slot and connected to a phase terminal at one end and to a neutral point at the other end. The phase coils are respectively composed of unit coils connected in series between a corresponding one of the phase terminals and a neutral point, and are connected together using conductors. Each phase coil includes two or more reverse connecting conductors, each of which is oriented so that the direction in which the connecting conductor extends from the i+1th unit coil to the i+2th unit coil is opposite to the direction in which the connecting conductor extends from the i-th unit coil to the i+1th unit coil. This coil layout ensures the desired degree of electrical insulation in the stator.

Description

Technical Field

[0001] The present disclosure generally relates to a rotating electric machine. Background Art

[0002] Japanese Patent First Publication No. 2014-217136A discloses a stator winding used in a rotating electric machine. The stator winding is equipped with phase coils, each of which is composed of a plurality of unit coils wound in an overlapping winding form. The unit coils are connected in series with each other using connecting conductors. Specifically, the unit coils are made of conductor segments, each of which extends across a given number m of slots formed in a stator core and is arranged in the slots. The stator core has an outer connecting conductor arranged on its radial outer side and an inner connecting conductor arranged on its radial inner side. The slot spacing of the outer connecting conductor is selected to be an interval corresponding to (m-1) slots. The slot spacing of the inner connecting conductor is selected to be an interval corresponding to (m+1) slots. Alternatively, the slot spacing of the outer connecting conductor is selected to be an interval corresponding to (m+1) slots. The slot spacing of the inner connecting conductor is selected to be an interval corresponding to (m-1) slots.

[0003] Specifically, each phase coil of the stator winding includes 2n unit coils connected in series to have a first end and a second end. The first end is connected to a corresponding one of the corresponding phase terminals (i.e., a voltage terminal). The second end is connected to a neutral point. The 2n unit coils are divided into two groups: a first coil group and a second coil group. The first coil group extends in a clockwise direction from the phase terminal to occupy the entire periphery of the stator core. The second coil group extends in a counterclockwise direction from the first coil group to occupy the entire periphery of the stator core.

[0004] In the above structure of the stator winding, the unit coils are electrically connected in series with each other, and the voltage level generated at each unit coil depends on the length of the electrical conductor between itself and the phase terminal, so that the voltage levels at the unit coils are different from each other. The closer to the phase terminal, the higher the voltage generated at the unit coil. Overlapping windings usually produce a high potential difference between the unit coils, which may lead to reduced electrical insulation between the conductors of the unit coils. In order to ensure the desired degree of electrical insulation, it is necessary to increase the thickness of the insulating layer of the conductor. Summary of the invention

[0005] Therefore, an object of the present disclosure is to provide a rotating electric machine capable of controlling a decrease in the degree of electrical insulation of a stator.

[0006] According to one aspect of the present disclosure, a rotating electric machine is provided, comprising: (a) a stator, the stator comprising a stator core and a stator winding, a plurality of slots arranged adjacent to each other are formed in the stator core along the circumferential direction of the stator core, the stator winding being equipped with a plurality of phase coils wound in the slots; and (b) a rotor, the rotor being configured to face the stator and having a plurality of magnetic poles arranged adjacent to each other along the circumferential direction of the rotor. The phase coils are connected to corresponding phase terminals at their first ends and to a neutral point at their second ends. Each phase coil comprises a plurality of unit coils, which are connected in series to each other in a joining order starting from a corresponding one of the phase terminals. The unit coils are arranged away from each other at a given slot spacing between a corresponding one of the phase terminals and the neutral point. The unit coils are connected together using a connecting conductor. The connecting conductor includes a first connecting conductor and a second connecting conductor, the first connecting conductor connecting the i-th unit coil counted from the corresponding one of the phase terminals to the i+1-th unit coil in a joining order, and the second connecting conductor connecting the i+1-th unit coil counted from the corresponding one of the phase terminals to the i+2-th unit coil in a joining order. Each phase coil includes more than two reverse connecting conductors, each of which is provided by the second connecting conductor and is oriented so that in the circumferential direction of the stator core, the direction in which the second connecting conductor extends from the i+1-th unit coil to the i+2-th unit coil is opposite to the direction in which the first connecting conductor extends from the i-th unit coil to the i+1-th unit coil.

[0007] As described above, the above-mentioned rotating electric machine has a stator winding equipped with phase coils. The unit coil of each phase coil is arranged between a corresponding one of the phase terminals and the neutral point, and is configured in a slot of the stator core. If two unit coils of the same phase (one close to the phase terminal and the other close to the neutral point) are configured in the same slot, this will cause an increase in the potential difference occurring at these unit coils, which may cause a decrease in electrical insulation between them.

[0008] In order to alleviate the above-mentioned problems, the rotating electric machine in the present disclosure is designed to have at least two reverse connecting conductors in each phase coil. Each reverse connecting conductor is provided by one of the connecting conductors connecting the i+1th unit coil to the i+2th unit coil, and is oriented so that in the circumferential direction of the stator core, the direction in which one of the connecting conductors extends is opposite to the direction in which one of the connecting conductors connects the i-th unit coil to the i+1th unit coil. This enables those unit coils that are positioned close to each other in the order of engagement starting from the phase terminal to be arranged in the same slot, thereby minimizing the undesirable increase in the potential difference between the unit coils to ensure the desired degree of electrical insulation in the stator.

[0009] In a first preferred mode of the present disclosure, each phase coil may include at least two series-connected coil groups divided from the unit coil. The series-connected coil groups are connected in series with each other. Each series-connected coil group is equipped with a reverse connection conductor.

[0010] As described above, each series-connected coil group is provided with the reverse-connection conductor(s), thereby increasing the number of reverse-oriented unit coils, which helps promote a reduction in the potential difference between the unit coils.

[0011] In the second preferred mode, each coil group connected in series can be designed to include four unit coils connected in series with each other. The connecting conductor includes a first connection portion, a second connection portion, and a third connection portion. The first connection portion is connected between the first unit coil and the second unit coil, the first unit coil being the first one of the unit coils of each coil group connected in series, and the second unit coil being the second one of the unit coils, which is counted from the corresponding one of the phase terminals in the engagement sequence. The second connection portion is connected between the second unit coil and the third unit coil, and the third unit coil is the third one of the unit coils, which is counted from the corresponding one of the phase terminals in the engagement sequence. The third connection portion is connected between the third unit coil and the fourth unit coil, and the fourth unit coil is the fourth one of the unit coils, which is counted from the corresponding one of the phase terminals in the engagement sequence. In the circumferential direction of the stator core, the direction in which the second connection portion extends from the second unit coil to the third unit coil is opposite to the direction in which the first connection portion extends from the first unit coil to the second unit coil. In the circumferential direction of the stator core, the direction in which the third connection portion extends from the third unit coil to the fourth unit coil is opposite to the direction in which the second connection portion extends. The second connection portion and the third connection portion are used as reverse connection conductors.

[0012] In short, each coil group connected in series has a first connection portion, a second connection portion and a third connection portion, which are opposite in orientation to each other, and each of the above coil groups consists of four unit coils. This enables the unit coils positioned close to each other in the joining order to be arranged in the same slot, resulting in a reduced potential difference between the unit coils. Two reverse connection conductors can be provided for each pole pair in the circumferential direction.

[0013] In a third preferred mode, each phase coil may include two or more series-connected coil groups connected in parallel to each other and may occupy the entire circumference of the stator core. Each series-connected coil group of each phase coil occupies an angular range of the stator core that is less than the entire circumference of the stator core. The series-connected coil groups are offset from each other in the circumferential direction of the stator core.

[0014] As described above, each series-connected coil group of each phase coil extends over an angular range smaller than the entire circumference of the stator core, thereby facilitating easy provision of each series-connected coil group with a reverse connection conductor that reverses the connection direction.

[0015] In a fourth preferred mode, each phase coil may be composed of m unit coils connected in series with each other between a corresponding one of the phase terminals and a neutral point. Two or more reverse connection conductors are arranged over the entire circumference of the stator core.

[0016] As described above, the m unit coils of each phase coil are connected in series with each other between the phase terminal and the neutral point. In other words, the unit coils are all connected in series with each other, rather than in parallel. This coil layout enables two or more reverse connection conductors to be configured within the entire circumference of the stator core, thereby effectively reducing the potential difference between the unit coils in the intermediate range between the phase terminal and the neutral point.

[0017] In a fifth preferred mode, 2k slots may be formed in the stator core for each pole and each phase, where k is a natural number. The unit coil may be made of a conductor wound in an overlapping winding form. The unit coil has coil sides arranged in the slots in a multi-layer form stacked in the radial direction of the stator core. If one pole pitch is defined as j slot pitches, the connecting conductor extends at least one of j slot pitches, j-1 slot pitches, and j+1 slot pitches in the circumferential direction of the stator core.

[0018] In the above-mentioned coil layout in which the conductor is wound in the form of overlapping windings, the conductor is arranged in each slot in the form of radially stacked multiple layers. The coil units arranged adjacent to each other on the radial innermost side or the radial outermost side of the stator core can be connected together using connecting conductors. The unit coils of the same phase are arranged in 2k slots for each pole. The connecting conductors are connected between slots arranged away from each other at j slot spacings or j±1 slot spacings. This layout helps to reverse the circumferential orientation (i.e., the connection direction) of the connecting conductor. This structure enables the length of the connecting conductor to be reduced.

[0019] In the sixth preferred mode, each unit coil can be made of a plurality of conductor segments, each of which includes a pair of straight portions and a bend portion connecting the straight portions together. The straight portions of the conductor segments are joined together in the form of overlapping windings. Each connecting conductor is connected between the excess portions of the straight portions of the corresponding two unit coils arranged adjacent to each other in sequence according to the joining order.

[0020] As described above, each unit coil is composed of a plurality of conductor segments. This structure facilitates easy change of the slot pitch of the unit coil or the connecting conductor by changing the circumferential size of the bend portion connecting the straight portion or the circumferential interval between the welded portions at the ends of the straight portion.

[0021] In the seventh preferred mode, the connecting conductors may be alternately arranged on the first radial side and the second radial side of the stator core in the order of joining the unit coils. If one pole pitch is defined as j slot pitches, the connecting conductors on the first radial side of the stator core extend j slot pitches in the circumferential direction of the stator core. The connecting conductors on the second radial side of the stator core extend j±1 slot pitches in the circumferential direction of the stator core.

[0022] In the eighth preferred mode, similar to the seventh preferred mode, the connecting conductors may be alternately arranged on the first radial side and the second radial side of the stator core in the order of joining the unit coils. If one pole pitch is defined as j slot pitches, the connecting conductors on the first radial side of the stator core may extend alternately by j slot pitches and j+1 slot pitches in the circumferential direction of the stator core. The connecting conductors on the second radial side of the stator core may extend alternately by j-1 slot pitches in the circumferential direction of the stator core.

[0023] In the ninth preferred mode, similar to the seventh preferred mode, the connecting conductors may be alternately arranged on the first radial side and the second radial side of the stator core in the order of joining the unit coils. If one pole pitch is defined as j slot pitches, the connecting conductors on the first radial side of the stator core may extend alternately by j slot pitches and j+1 slot pitches in the circumferential direction of the stator core. The connecting conductors on the second radial side of the stator core may extend alternately by j slot pitches and j±1 slot pitches in the circumferential direction of the stator core.

[0024] In the tenth preferred mode, the phase coils may be arranged to have a given phase difference between ends leading to the phase terminals. The given phase difference satisfies the relationship of [480° / (the number of pole pairs×the number of arrays of unit coils connected in series to each other)].

[0025] In the above structure, the ends of the phase coils close to the phase terminals are dispersedly arranged in the circumferential direction of the stator core, thereby reducing the potential difference between the unit coils of different phases arranged adjacent to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be more fully understood through the detailed description given below and the drawings of preferred embodiments of the present invention, however, the detailed description and the drawings should not be considered to limit the present invention to specific embodiments, but they are only for the purpose of description and understanding.

[0027] In the attached picture:

[0028] Figure 1 is a cross-sectional view showing the overall structure of the rotating electrical machine;

[0029] Figure 2 It is shown installed in Figure 1 A perspective view of a stator core in a rotating electrical machine;

[0030] FIG3(a) shows Figure 1 A circuit diagram of a circuit of a rotating electrical machine;

[0031] FIG. 3( b ) shows a schematic diagram of a Figure 1 An expanded view of a stator winding in a rotating electrical machine;

[0032] Figure 4 is a diagram showing the structure of a unit coil having an overlapping winding structure;

[0033] Figure 5 is a partial view showing conductors arranged in a slot in a multi-layered form;

[0034] Figure 6 is a view showing a conductor segment;

[0035] Figure 7 is a partial view showing the order in which unit coils are joined together in a stator core;

[0036] Figure 8 is a developed plan view showing the order in which the unit coils are joined together;

[0037] Fig. 9 is a view showing the circumferential positions of the unit coils and the orientation of the connecting conductors connecting the unit coils together;

[0038] Fig.10 is a developed plan view showing the order in which unit coils are joined together in a conventional stator;

[0039] Fig.11 is a view showing the circumferential positions of unit coils in a conventional stator and the orientation of connection conductors connecting the unit coils together;

[0040] Fig.12 is a view showing the numbering of slots in which unit coils are arranged and the potential difference between the unit coils;

[0041] Fig.13 is a plan view showing the circumferential positions of the neutral point and phase terminals;

[0042] Fig.14 is a developed plan view showing the order in which the unit coils are joined together in the first modification of the first embodiment;

[0043] Fig.15 is a view showing the circumferential positions of the unit coils and the orientation of the connecting conductors connecting the unit coils together in the first modification of the first embodiment;

[0044] Fig.16 is a view showing the numbers of slots in which the unit coils are arranged and the potential differences between the unit coils in the first modification of the first embodiment;

[0045] Fig.17 is a developed plan view showing the order in which the unit coils are joined together in the second modification of the first embodiment;

[0046] Fig.18 is a view showing the circumferential positions of the unit coils and the orientation of the connecting conductors connecting the unit coils together in a second modification of the first embodiment;

[0047] Fig.19 is a view showing the numbers of slots in which the unit coils are arranged and the potential differences between the unit coils in a second modification of the first embodiment;

[0048] Fig. 20 is a development diagram showing a stator winding according to a second embodiment;

[0049] Fig.21 is a developed plan view showing the order in which unit coils are joined together in the second embodiment;

[0050] Fig. 22 is a view showing the circumferential positions of the unit coils and the orientation of the connecting conductors connecting the unit coils together in the second embodiment;

[0051] 23(a), 23(b) and 23(c) are views showing the circumferential positions of the unit coils and the orientation of the connecting conductors connecting the unit coils together in a modification of the second embodiment;

[0052] Fig.24 is a development diagram showing a stator winding according to a third embodiment;

[0053] 25( a) and 25( b) are views showing the circumferential positions of unit coils and the orientation of connecting conductors connecting the unit coils together in the third embodiment;

[0054] 26( a ) and 26( b ) are perspective views showing the structure of a stator according to a fourth embodiment;

[0055] Fig. 27 is a partial view showing the order in which unit coils are joined together in the stator core in the fourth embodiment;

[0056] 28( a ), 28( b ) and 28( c ) are views schematically showing variations of conductor segments;

[0057] 29( a ) and 29( b ) are partially enlarged perspective views showing coil ends of a stator in a fourth embodiment;

[0058] Fig.30 is a view showing the circumferential positions of the unit coils and the orientation of the connecting conductors connecting the unit coils together in the fourth embodiment;

[0059] Fig.31 is a partial view showing the order in which unit coils are joined together in a stator core in a first modification of the fourth embodiment;

[0060] Fig.32 is a partial view showing the order in which unit coils are joined together in the stator core in the second modification of the fourth embodiment. DETAILED DESCRIPTION

[0061] First embodiment

[0062] The rotating electric machine according to the present embodiment will be described below with reference to the accompanying drawings. The rotating electric machine in the present embodiment is designed as an electric drive motor that outputs drive power or torque to move an electric vehicle.

[0063] First, the overall structure of the rotating electrical machine 10 will be described. Figure 1 1 is a cross-sectional view showing the overall structure of the rotating electric machine 10. In the following discussion, the direction in which the rotation center axis of the rotating electric machine 10 is oriented will be referred to as the axial direction. The direction oriented perpendicular to the rotation center axis of the rotating electric machine 10 will be referred to as the radial direction. The direction extending circumferentially around the rotation center axis of the rotating electric machine 10 will be referred to as the circumferential direction. Figure 1 As shown, the rotary electric machine 10 is designed as an inner rotor type three-phase AC rotary electric machine, and includes a housing 11 , a rotor 20 , and a stator 30 .

[0064] The rotor 20 includes a rotating shaft 21, a rotor core 22, and a plurality of permanent magnets 23. The rotor core 22 is firmly fixed to the rotating shaft 21. The rotating shaft 21 is rotatably held by the housing 11 using bearings 12, 13. The permanent magnets 23 are arranged away from each other at a given interval in the circumferential direction of the rotor core 22, and are magnetized to have the following polarity: N poles and S poles arranged alternately in the circumferential direction, so that a plurality of magnetic poles are arranged adjacent to each other in the circumferential direction. The rotor 20 may be another type, such as a field winding type in which a field winding is wound around a claw pole core.

[0065] The stator 30 is arranged outside the rotor 20 in its radial direction. The stator 30 includes a stator core 31 and a stator winding 32. The stator core 31 is in a hollow cylindrical shape and is fixed to the inner surface of the circumferential wall of the housing 11. The stator core 31 is made of a stack of magnetic steel plates placed one on top of the other in the axial direction. Figure 2 As shown, the stator core 31 includes an annular support yoke 33 and pole teeth 34 extending inwardly from the support yoke 33 in the radial direction of the stator core 31. The stator core 31 also has slots 35, each of which is formed between two corresponding adjacent pole teeth 34. The rotating electric machine 10 in the present embodiment is designed so that the number of magnetic poles is eight, the number of pole pairs is four, and the number of slots for each pole and each phase is two. In other words, a total of forty-eight slots 35 arranged adjacent to each other in the circumferential direction thereof are formed in the stator core 31. In other words, 2k slots 35 are formed in the stator core 31 for each pole and each phase, where k is a natural number.

[0066] The stator winding 32 is made of a conductor wound through slots 35 of the stator core 31. The stator core 31 has coil ends 36 of the stator winding 32 extending to the outside of one of its opposite axial ends in the axial direction, and also has coil ends 37 of the stator winding 32 extending to the outside of the other of the opposite axial ends in the axial direction.

[0067] Fig. 3(a) is a circuit diagram showing an electrical structure for the stator winding 32. The stator winding 32 includes the following phase coils: a U-phase coil 32U, a V-phase coil 32V, and a W-phase coil 32W. The U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W are joined together at a neutral point N in the form of a star connection (also called a Y connection).

[0068] As shown in FIG. 3( b), each of the phase coils 32U, 32V, 32W is made of a plurality of unit coils U1 to U16, V1 to V16 or W1 to W16 connected in series with each other. Each unit coil is made of a coil conductor configured in two slots 35, and the two slots 35 are separated from each other by a given slot spacing (also referred to as a coil span or coil spacing) in the form of overlapping windings. The unit coils are joined together using jumper wires connected in series with each other. In the structure of FIG. 3( b), each of the phase coils 32U, 32V, 32W can also be regarded as including a plurality of coil groups connected in series. The coil groups connected in series are connected in series with each other to complete a corresponding one of the phase coils 32U, 32V, 32W.

[0069] Figure 4A unit coil 41 having an overlapping winding structure is shown. Each unit coil 41 is made of a conductor CR having a coil side occupying an area indicated by "CS" and a coil end occupying an area indicated by "CE". The coil side extends vertically, i.e., in the axial direction, and is arranged inside the slot 35. The coil end protrudes to the outside of the slot 35 in the axial direction. The conductor CR is made of a rectangular conductor having a substantially rectangular cross-section. The conductor CR is wound multiple times in the form of overlapping windings to complete a plurality of unit coils 41. In the present embodiment, the number of turns of the unit coils 41 is the same as each other. Portions of the unit coils 41 are used as jumper wires 42 to join the unit coils 41 together. The conductor CR may alternatively be made of a round wire having a circular cross-section.

[0070] like Figure 5 As clearly shown in FIG. 1 , the stator core 31 has conductors CR arranged in slots 35 in the form of multiple layers stacked one on another in the radial direction of the stator core 31. The conductors CR are wound in the form of overlapping windings to sequentially form turns in each slot 35 from the radial outside or the radial inside, so that the turns of the conductors CR are arranged radially adjacent to each other in each slot 35.

[0071] like Figure 6 As shown, the conductor CR may be made of conductor segments 50. Each conductor segment 50 is formed of a U-shaped rectangular conductor including two straight portions 51 and one bent portion 52 connecting the straight portions 51 together. Each straight portion 51 has a length longer than the axial length of the stator core 31, and also has an end away from the bent portion 52 as a redundant portion 53. After the conductor segment 50 is inserted into the slot 35, the redundant portion 51 of the straight portion 51 protrudes to the outside of the slot 35. The corresponding redundant portions 53 of the two conductor segments 50 are joined or welded together, thereby joining all the conductor segments 50 together.

[0072] Instead of using discrete conductor segments 50, the unit coils 41 for each phase coil may instead be made from a single continuous conductor.

[0073] 3( b ) again, the structure of each of the phase coils 32U, 32V, 32W will be described below. Each of the phase coils 32U, 32V, 32W includes a plurality of unit coils 41. For ease of discussion below, the unit coils 41 of the U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W will be referred to as unit coils U, unit coils V, and unit coils W, respectively.

[0074] The U-phase coil 32U is made of sixteen unit coils U1 to U16 electrically connected to each other in sequence. The U-phase coil 32U is connected to the U-phase terminal T1 at one end close to the unit coil U1 and is connected to the neutral point N at one end close to the unit coil U16.

[0075] Similarly, the V-phase coil 32V is made up of sixteen unit coils V1 to V16 that are electrically connected to each other in sequence. The V-phase coil 32V is connected to the V-phase terminal T2 at one end close to the unit coil V1, and is connected to the neutral point N at one end close to the unit coil V16. The W-phase coil 32W is made up of sixteen unit coils W1 to W16 that are electrically connected to each other in sequence. The W-phase coil 32W is connected to the W-phase terminal T3 at one end close to the unit coil W1, and is connected to the neutral point N at one end close to the unit coil W16.

[0076] As clearly shown in FIG. 3( a), an inverter 61 composed of a plurality of switches is connected between the battery 60 and the phase terminals T1 to T3. Specifically, the inverter 61 is made of a bridge circuit equipped with the same number of upper arms and lower arms as the phases of the stator winding 32, and constitutes a three-phase full-wave rectifier. The inverter 61 is used as a drive circuit to control the amount of power delivered to the rotating electric machine 10 so that the rotating electric machine 10 is driven or operated. Specifically, the inverter 61 is equipped with switches Sp, Sn for each phase. The switches Sp, Sn are connected in series with each other, and are also connected to a corresponding one of the phase terminals T1 to T3 of the phase coils 32U, 32V, 32W at the joint therebetween. The inverter 61 operates in a switching operation mode to adjust the amount of excitation current flowing through the rotating electric machine 10.

[0077] The inverter 61 is equipped with an upper arm switch Sp and a lower arm switch Sn for each of the U phase, the V phase and the W phase. Each of the switches Sn and Sp is implemented by a voltage-controlled semiconductor switch, i.e., an N-channel MOSFET. The upper arm switch Sp has an upper arm diode Dp connected in reverse parallel thereto. Similarly, the lower arm switch Sn has a lower arm diode Dn connected in reverse parallel thereto. In the present embodiment, the diodes Dp and Dn are respectively implemented by the main diodes (i.e., parasitic diodes) of the switches Sp and Sn, but they can also be implemented alternatively using diodes separated from the switches Sp and Sn.

[0078] When the vehicle is driven, the controller 62 outputs an on / off signal to the switches Sp, Sn to deliver the three-phase AC voltage from the battery 60 to the stator winding 32 through the inverter 61, thereby rotating the rotor 20. The rotating shaft 21 of the rotor 20 is directly engaged to the crankshaft of the vehicle engine (not shown) or engaged through a clutch and / or a gear. In the case of direct engagement, the rotating shaft 21 rotates to start the engine.

[0079] The rotating electrical machine 10 may be designed to have the structure discussed below.

[0080] The inner rotor type rotating electrical machine 10 has an outer diameter ratio derived by dividing the outer diameter of the stator 30 (ie, the diameter of the outer circumference of the stator 30 ) by the outer diameter of the rotor 20 (ie, the diameter of the outer circumference of the rotor 20 ) and is in the range of 1.2 to 1.7.

[0081] The stack thickness to outer diameter ratio derived by dividing the thickness of the stator core 31 (i.e., the dimension of the stator core 31 in its axial direction) by the outer diameter of the rotor 20 (i.e., the diameter of the outer circumference of the rotor 20) is selected to be greater than 0.6. In this case, the rotary electric machine 10 is not a flat type but a long axis type suitable for high voltage.

[0082] The ratio of the coil end height to the stack thickness, which is derived by dividing the height of the coil end from one end of the stator 30 by the thickness of the stator core 31 (i.e., the dimension of the stator core 31 in its axial direction), is selected to be 0.25 or less. In the segmented stator winding 32 as described above, the height of the coil end can be reduced, thereby increasing the power density of the rotating electric machine 10.

[0083] The winding structure of the stator 30 having unique features will be described in detail below.

[0084] Figure 7 1 is a plan view showing the order or sequence (also referred to as the joining sequence) of steps in which the unit coils of the stator core 31 are joined to each other starting from, for example, the U-phase terminal T1 . Figure 8 is a developed plan view showing the sequence of steps for joining the unit coils to each other. For convenience, Figure 7 and Figure 8 Each of the diagrams shows only the U-phase coil 32U. Figure 7 and Figure 8 In the embodiment, slots 35 are numbered from 1 to 48, and will also be referred to as slots 1 to 48 below. Figure 8 The unit coils U1 to U16 configured in slots 1 to 48 are shown. For simplicity, Figure 7 Only the unit coils U1 to U4 are shown. Figure 8 The rightward direction in corresponds to Figure 7 In the clockwise direction.

[0085] exist Figure 7 and Figure 8, the order in which the unit coils U1 to U16 are connected starting from the starting point of the U-phase terminal T1 is indicated by arrows. Solid arrows represent the unit coils U1 to U16. Hollow arrows represent the jumpers or connecting parts of the unit coils U1 to U16. The connecting parts (hereinafter also referred to as connecting conductors) that connect two of the unit coils U1 to U16 arranged adjacent to each other in the connection order are represented by symbols "A1" to "A15". For example, the connecting part A1 connects the unit coils U1 and U2 together. The connecting part A2 connects the unit coils U2 and U3 together. The connecting part A3 connects the unit coils U3 and U4 together. The same is true for the following connecting parts.

[0086] For convenience, only refer to Figure 7 and Figure 8 Of the unit coils U1 to U4 of the U-phase coil 32U, the unit coil U1 is configured in slots 2 and 8. The unit coil U2 is configured in slots 7 and 13. The unit coil U3 is configured in slots 1 and 7. The unit coil U4 is configured in slots 8 and 14. Pairs of slots 1 and 2, pairs of slots 7 and 8, and pairs of slots 13 and 14 are used for the same phase and the same magnetic pole. In this pairing, only unit coils of the same phase, such as unit coils U1 to U8 of the U phase, are configured in the example shown. The connection portion A1 is connected between slots 2 and 7. The connection portion A2 is connected between slots 7 and 13. The connection portion A3 is connected between slots 1 and 8. Between the unit coil U4 and the subsequent unit coil U5, the connection portion A4 is connected between slots 14 and 20.

[0087] Each of the unit coils U1 to U4 extends 6 slot pitches, in other words, has coil sides (i.e., straight portions 51) arranged away from each other by 6 slot pitches. At least two of the connecting portions A1 to A3 connecting the unit coils U1 to U4 together are different from each other in slot pitch. Specifically, in the present embodiment, the connecting portion A1 is connected between two slots 35 (i.e., two coil sides) positioned away from each other by 5 slot pitches. The connecting portion A2 is connected between two slots 35 positioned away from each other by 6 slot pitches. The connecting portion A3 connects two slots 35 positioned away from each other by 7 slot pitches.

[0088] In the present embodiment, the pole pitch is equal to 6 slot pitches. If the number of slots 35 corresponding to the pole pitch is defined as "j", each of the unit coils U1 to U4 has a coil side portion arranged away from each other by j slot pitches. The connection portion A1 is connected between the slots 35 arranged away from each other by (j-1) slot pitches. The connection portion A2 is connected between the slots 35 arranged away from each other by j slot pitches. The connection portion A3 is connected between the slots 35 arranged away from each other by (j+1) slot pitches. The connection portion A4 extending from the unit coil U4 is connected between the slots 35 arranged away from each other by j slot pitches.

[0089] The orientation or direction (hereinafter also referred to as the connection direction) in which the connection parts A1 to A3 of the unit coils U1 to U4 extend circumferentially is different in the order of connection starting from the U-phase terminal T1. Figure 8 The connecting portion A2 extends in the counterclockwise direction (ie, Figure 8 Therefore, the unit coils U1 to U4 are turned or folded several times, in other words, the directions in which the unit coils U1 to U4 extend are reversed several times until they extend across the entire circumference of the stator core 31.

[0090] Specifically, the direction in which the connection portion A2 extends from the unit coil U2 to the unit coil U3 is opposite to the direction in which the connection portion A1 extends from the unit coil U1 to the unit coil U2. The connection portion A2 will also be referred to as the reverse connection portion hereinafter. The direction in which the connection portion A3 extends from the unit coil U3 to the unit coil U4 is opposite to the direction in which the connection portion A2 extends from the unit coil U2 to the unit coil U3. The connection portion A3 will also be referred to as the reverse connection portion hereinafter.

[0091] Although not described in detail, the unit coils U5 to U8, unit coils U9 to U12, and unit coils U13 to U16 extending from or following the unit coils U1 to U4 have the same arrangement as the unit coils U1 to U4. In short, the U-phase coil 32U includes four coil groups (hereinafter also referred to as arrays) connected in series, each coil group consisting of four unit coils U1 to U16, respectively. The four coil groups connected in series are connected in series to complete the U-phase coil 32U. Each coil group connected in series includes two reverse connection portions. In the following discussion, the reverse connection portion will also be referred to as a reverse connection conductor.

[0092] Fig. 93 is a view showing the circumferential positions of the unit coils U1 to U16 of the U-phase coil 32U, and the connection directions of the connection parts A1 to A15 of the U-phase coil 32U. As can be seen in the figure, the connection parts A2, A6, A10, A14 of the U-phase coil 32U are oriented in a counterclockwise direction between the U-phase terminal T1 and the neutral point N. The connection directions of the connection parts A2, A6, A10, A14 are opposite to the connection directions of the other connection parts. Therefore, those of the unit coils U1 to U16 that are relatively close to each other are arranged in the same slot 35, thereby reducing the potential difference between the unit coils U1 to U16.

[0093] The segment structure of the stator winding 32 will be described below. Each conductor segment 50 has two straight portions 51, which are arranged away from each other by 6 slot pitches and connected together by a bend portion 52. The same number of conductor segments 50 as the bend portion 52 of each of the unit coils U1 to U16 are arranged in the same slot 35. For each of the unit coils U1 to U16, the conductor segment 50 is wound in the form of overlapping windings. The excess portions 53 of the corresponding two conductor segments 50 arranged adjacent to each other in the unit coils U1 to U16 in the joining order are joined or welded together to form a corresponding one of the connection portions A1 to A15.

[0094] like Figure 8 As shown, the vertical direction corresponds to the radial direction of the stator core 31. The downward direction corresponds to the radially inward direction. The upward direction corresponds to the radially outward direction. At the radially innermost side of the stator core 31, each of the connection parts A2, A4, A6, A8, A10, A12, A14 is connected between the slots 35 arranged 6 slot pitches away from each other. At the radially outermost side of the stator core 31, each of the connection parts A1, A3, A5, A7, A9, A11, A13, A15 is connected between the slots 35 arranged 7 slot pitches away from each other. If the pole pitch is generally defined as j (=6 slot pitches), each of the connection parts A2, A4, A6, A8, A10, A12, A14 on the radially innermost side of the stator core 31 is connected between the slots 35 arranged j slot pitches away from each other. Each of the connecting portions A1, A3, A5, A7, A9, A11, A13, A15 connects between the slots 35 arranged away from each other by j±1 slot pitches.

[0095] The above-mentioned slot spacing of the connection parts A1 to A15 may alternatively be reversed between the radial outer side and the radial inner side of the stator core 31. Specifically, each of the connection parts A2, A4, A6, A8, A10, A12, A14 on the radial innermost side of the stator core 31 may be connected between slots 35 arranged away from each other by (j±1) slot spacings. Each of the connection parts A1, A3, A5, A7, A9, A11, A13, A15 on the radial outermost side of the stator core 31 may be connected between slots 35 arranged away from each other by j slot spacings. Instead of those connection parts in all the connection parts A1 to A15, some bends 52 of the conductor segments 50 may alternatively be used as connection parts. The use of the bends 52 as connection parts can be achieved by designing some conductor segments 50 so that the spacing between the straight parts (i.e., the coil side parts) 51 is different from the spacing between other conductor segments 50 and is the same as the required slot spacing.

[0096] Next, a description will be given of a reduction in the potential difference between the unit coils U1 to U16 achieved by the winding structure of the present embodiment.

[0097] In the following discussion, reference will be made to the following comparative example: Figure 8 , the sixteen unit coils U1 to U16 are connected in series with each other to have Fig.10 The winding structure shown is a conventional stator winding (eg, U-phase coil 32U). Fig.11 FIG. 2 shows the circumferential positions of the unit coils U1 to U16 in the existing stator winding and the connection direction of the connection portion. Fig.11 As can be seen in FIG. 1 , connection portions A1 to A8 of unit coils U1 to U9 are oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. Connection portions A9 to A15 of unit coils U9 to U16 are oriented in a counterclockwise direction between the U-phase terminal T1 and the neutral point N.

[0098] Fig.12 1 is a diagram showing the number of slots in which the unit coils U1 to U16 of the U-phase coil 32U of each of the stator winding 32 in the present embodiment and the above-mentioned conventional stator winding are arranged, and the potential difference between two of the unit coils U1 to U16 arranged in each slot. Figure 8 The unit coils U1 to U6 arranged in the slots of the existing stator winding are numbered the same as Fig.10 Same as in.

[0099] In the existing stator winding, the unit coils U1 to U16 are folded in their direction, in other words, reversed once, only at the midpoint between the unit coils U1 to U16, that is, between the U-phase terminal T1 and the neutral point N. Thus, each of the unit coils U1 to U16 arranged at a position closer to the U-phase terminal T1 than the midpoint is paired with a corresponding one of the other of the unit coils U1 to U16 arranged at a position closer to the neutral point than the midpoint, and are arranged in the same slot on a paired basis, resulting in an increase in the potential difference between the unit coils U1 to U16.

[0100] In the stator winding 32 of the present embodiment, the unit coils U1 to U4 have two reverse connection portions. In other words, the unit coils U1 to U4 are reversed twice in their directions. Therefore, a total of eight reverse connection portions are configured between the U-phase terminal T1 and the neutral point N. This results in a reduction in the potential difference between the unit coils U1 to U16 configured in the same slot.

[0101] Although not shown, the V-phase coil 32V, the W-phase coil 32W have the same structure as the U-phase coil 32U. Only one or two of the phase coils 32U, 32V, 32W may be designed to have the above-described structure.

[0102] Fig.13 The phase terminals T1, T2, T3 (at Fig.13 and will also be represented by “U”, “V” and “W” in the following figures) and the circumferential position of the neutral point N of the U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W.

[0103] exist Fig.13, the circumferential position of the end of the U-phase coil 32U leading to the U-phase terminal U coincides with the 8th slot. The circumferential position of the end of the V-phase coil 32V leading to the V-phase terminal V coincides with the 24th slot. The circumferential position of the end of the W-phase coil 32W leading to the W-phase terminal W coincides with the 40th slot. The above-mentioned ends of the U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W (hereinafter also referred to as the first end) are arranged at equal angular intervals away from each other in the circumferential direction of the stator core 31. In other words, each end of the U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W is positioned to have a phase difference of 120° between itself and the others. Similarly, the ends of the phase coils 32U, 32V, and 32W leading to the neutral point N (hereinafter also referred to as the second end) are arranged at equal angular intervals away from each other in the circumferential direction of the stator core 31 to have a phase difference of 120° between them. In summary, the first ends of the phase coils 32U, 32V, 32W leading to the U-phase terminal U, V-phase terminal V, and W-phase terminal W are arranged to have a phase difference of [480° / (number of pole pairs×number of phase coils connected in parallel to each other)].

[0104] The rotary electric machine 10 in the present embodiment provides the following advantageous advantages.

[0105] The rotary electric machine 10 is designed to have two or more reverse connection portions in each of the phase coils 32U, 32V, 32W. Each of the reverse connection portions of each of the phase coils 32U, 32V, 32W is provided by one of the connection portions A1 to A15 (hereinafter also referred to as the second connecting conductor), which connects the (i+1)th unit coil counted from the corresponding one of the U phase terminal T1, the V phase terminal T2, and the W phase terminal T3 in a joining order to the (i+2)th unit coil, and is oriented so that in the circumferential direction of the stator core 31 (i.e., the stator winding 32), the second connecting conductor extends from the (i+1)th unit coil counted from the corresponding one of the U phase terminal T1, the V phase terminal T2, and the W phase terminal T3 in a joining order to the (i+2)th unit coil in a direction opposite to the direction in which one of the connection portions connecting the i-th unit coil to the (i+1)th unit coil (hereinafter also referred to as the first connecting conductor) extends from the i-th unit coil to the (i+1)th unit coil. In other words, each of the phase coils 32U, 32V, 32W is folded or reversed two or more times in its orientation along the circumferential direction of the stator core 31. This allows those of the unit coils U1 to U16, V1 to V16, or W1 to W16 of the same phase that are close to each other from the viewpoint of the joining order to be arranged in the same slot of the stator core 31, thereby eliminating the risk that the potential difference between the unit coils U1 to U16, V1 to V16, or W1 to W16 may increase. This ensures the desired degree of electrical insulation of the stator 30.

[0106] As described above, each of the phase coils 32U, 32V, and 32W includes four coil groups connected in series, and each of the above coil groups is equipped with a reverse connection portion, which results in an increase in the number of parts of the corresponding one of the phase coils 32U, 32V, and 32W that are reversed in direction, which promotes the reduction of the potential difference between the unit coils.

[0107] As described above, each of the series-connected coil groups of each of the phase coils 32U, 32V, 32W includes four unit coils U1 to U16, V1 to V16, or W1 to W16 connected in series. For convenience, the following discussion will refer to the unit coils U1 to U4 as the corresponding four of the unit coils U1 to U16, V1 to V16, or W1 to W16. The series-connected coil group including the unit coils U1 to U4 is equipped with a first connection portion, a second connection portion, and a third connection portion, the first connection portion connecting the first coil unit (i.e., coil unit U1) and the second coil unit (i.e., coil unit U2) counted from the U-phase terminal T1 in the engagement order, the second connection portion connecting the second coil unit (i.e., coil unit U2) and the third coil unit (i.e., coil unit U3) counted from the U-phase terminal T1 in the engagement order, and the third connection portion connecting the third coil unit (i.e., coil unit U3) and the fourth coil unit (i.e., coil unit U4) counted from the U-phase terminal T1 in the engagement order. The third and fourth connections are selected as reverse connections. This allows those of the unit coils U1 to U4 that are arranged close to each other in the engagement sequence to be arranged in the same slot 35, thereby reducing the potential difference between the unit coils U1 to U4. In this case, each pole pair may include two reverse connections in the circumferential direction.

[0108] As described above, each of the phase coils 32U, 32V, 32W is composed of a total of sixteen (m) coil units (i.e., U1 to U16, V1 to V16, or W1 to W16) connected in series with each other from a corresponding one of the U-phase terminal T1, the V-phase terminal T2, and the W-phase terminal T3 to the neutral point N. Two or more reverse connection portions are placed within the range of the entire circumference of the stator core 31. This also helps to reduce the potential difference between the unit coils at the intermediate portion between the phase terminals and the neutral point.

[0109] Each unit coil is made of a conductor wound in the form of overlapping windings, and is arranged in the slot 35 in the form of multiple layers stacked in the radial direction of the stator core 31. Respective two of the unit coils that are arranged adjacent to each other in the circumferential direction of the stator core 31 and are located at the radial innermost or radial outermost side of the stator core 31 are connected together using a connecting portion. The unit coils of the same phase are arranged in corresponding two of the slots 35 for each pole. Each connecting portion is designed to connect two slots 35 that are arranged j or (j+1) slot pitches away from each other. This helps to reverse the connection direction (i.e., the circumferential direction) of the connecting portion to minimize the length of the connecting portion.

[0110] Each of the unit coils (i.e., U1 to U16, V1 to V16, or W1 to W16) is made of a plurality of conductor segments 50. This allows the length of a turn portion 52 connecting two straight portions 51 of each conductor segment 50 or the interval between the excess portions 53 of the straight portions 51 to be changed in the circumferential direction so as to change the slot pitch of the unit coils or the connecting portions.

[0111] The phase coils 32U, 32V, 32W are arranged to have a given phase difference between their ends close to, in other words, leading to, the phase terminals T1, T2, T3. The given phase difference is set to satisfy the relationship of [480° / (the number of pole pairs×the number of arrays of unit coils connected in parallel to each other)]. This reduces the potential difference between the corresponding adjacent two of the phase coils 32U, 32V, 32W.

[0112] The rotary electric machine 10 is not of a flat type but of a long-axis type suitable for high voltage, and therefore, it is essentially necessary to reduce the potential difference between the phase coils. The above-described structure of the rotary electric machine 10 is suitable for reducing the potential difference.

[0113] As described above, the stator winding 32 is a segmented structure. This structure makes it possible to reduce the height of the coil end to increase the power density of the rotating electric machine 10. The increase in power density can also be achieved by reducing the thickness of the insulating layer of the stator winding 32. However, the potential difference between adjacent phase coils must be reduced to ensure the desired degree of electrical insulation of the stator winding 32. Therefore, the above-mentioned structure of the stator winding 32 helps to obtain the desired degree of electrical insulation of the stator winding 32.

[0114] Modification of the First Embodiment

[0115] Next, a description will be given of a first modification of the structure of the stator winding 32. Similar to the above-described first embodiment, each of the phase coils 32U, 32V, 32W is composed of sixteen unit coils U1 to U16, V1 to V16, or W1 to W16.

[0116] Fig.14 1 is a developed plan view showing the sequence of steps for joining the unit coils U1 to U16, V1 to V16 or W1 to W16 to each other. Fig.14 With Figure 8 Only the U-phase coil 32U is shown in the same manner.

[0117] For simplicity, referring only to the unit coils U1 to U8 of the U-phase coil 32U, the unit coil U1 is configured in slots No. 1 and No. 8. The unit coil U2 is configured in slots No. 7 and No. 13. The unit coil U3 is configured in slots No. 14 and No. 20. The unit coil U4 is configured in slots No. 9 and No. 25. The unit coil U5 is configured in slots No. 13 and No. 19. The unit coil U6 is configured in slots No. 8 and No. 14. The unit coil U7 is configured in slots No. 1 and No. 7. The unit coil U8 is configured in slots No. 2 and No. 44. The connection portion A1 extends or connects between slots No. 2 and No. 7. The connection portion A2 connects between slots No. 13 and No. 20. The connection portion A3 connects between slots No. 14 and No. 19. The connection portion A4 extends or connects between slots No. 19 and No. 25. The connection portion A5 is connected between the slot No. 8 and the slot No. 13. The connection portion A6 is connected between the slot No. 7 and the slot No. 14. The connection portion A7 is connected between the slot No. 1 and the slot No. 44. Between the unit coil U8 and the subsequent unit coil U9, the connection portion A8 is connected between the slot No. 2 and the slot No. 43.

[0118] Each of the unit coils U1 to U8 extends 6 slot pitches. At least two of the connections A1 to A7 that connect the unit coils U1 to U8 together are different from each other in slot pitch. Specifically, in this modification, each of the connections A1, A3, A5, A7 is connected between two slots 35 (i.e., two coil sides) positioned 6 slot pitches away from each other. Each of the connections A2, A6 is connected between two slots 35 positioned 7 slot pitches away from each other.

[0119] If the number of slots 35 corresponding to the pole pitch (i.e., 6 slot pitches) is defined as "j", each of the unit coils U1 to U8 has coil sides arranged away from each other by j slot pitches. Each of the connecting portions A1, A3, A5, A7 is connected between slots 35 arranged away from each other by (j-1) slot pitches. The connecting portion A4 is connected between slots 35 arranged away from each other by j slot pitches. The connecting portions A2, A6 are respectively connected between slots 35 arranged away from each other by (j+1) slot pitches.

[0120] In the order of connection from the U-phase terminal T1, the directions in which the connection parts A1 to A7 of the unit coils U1 to U8 extend circumferentially (ie, the connection directions) are different from each other. Fig.14 The connecting parts A4 to A7 extend in the counterclockwise direction (ie, Fig.14 Therefore, the unit coils U1 to U8 are turned or folded several times, in other words, the direction in which the unit coils U1 to U8 extend is reversed several times until they are wound around the entire circumference of the stator core 31.

[0121] Specifically, the direction in which the connection portion A4 extends from the unit coil U4 to the unit coil U5 is opposite to the direction in which the connection portion A3 extends from the unit coil U3 to the unit coil U4. Therefore, the connection portion A4 is used as a reverse connection portion.

[0122] Although not described in detail, the unit coils U9 to U16 following the unit coils U1 to U8 have the same arrangement as the unit coils U1 to U8. In short, the U-phase coil 32U includes two coil groups connected in series, each coil group consisting of eight unit coils U1 to U16, respectively. The two coil groups connected in series are connected in series to complete the U-phase coil 32U. Each coil group connected in series includes a reverse connection portion.

[0123] Fig.15 32U, and the connection direction of the connecting parts A1 to A15 of the U-phase coil 32U. As can be seen in the figure, the connecting parts A1 to A3 of the U-phase coil 32U are oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. The connection direction of the connecting parts A4 to A11 is oriented in a counterclockwise direction. The connection direction of the connecting parts A12 to A15 is oriented in a clockwise direction again. Therefore, those of the unit coils U1 to U16 that are relatively close to each other are arranged in the same slot 35, thereby reducing the potential difference between the unit coils U1 to U16.

[0124] exist Fig.14 In the figure, at the radially innermost side of the stator core 31 (i.e., the lower side in the figure), each of the connection parts A2, A4, A6, ... is connected between the slots 35 arranged 6 slot pitches or 7 slot pitches away from each other. At the radially outermost side of the stator core 31 (i.e., the upper side in the figure), each of the connection parts A1, A3, A5, A7, ... is connected between the slots 35 arranged 5 slot pitches away from each other. If the pole pitch is generally defined as j (=6 slot pitches), each of the connection parts A2, A4, A6, ... on the radially innermost side of the stator core 31 is connected between the slots 35 arranged (j+1) slot pitches away from each other. Each of the connection parts A1, A3, A5, A7, ... is connected between the slots 35 arranged (j-1) slot pitches away from each other.

[0125] The above-mentioned slot pitches of the connection portions A1 to A15 may alternatively be reversed between the radially outer side and the radially inner side of the stator core 31. Specifically, each of the connection portions on the radially innermost side of the stator core 31 may be connected between slots 35 arranged away from each other by (j-1) slot pitches. Each of the connection portions on the radially outermost side of the stator core 31 may be connected between slots 35 arranged away from each other by j or (j+1) slot pitches.

[0126] Fig.163 is a view showing a reduction in the potential difference between the unit coils of the stator winding 32 in this modification and the existing stator winding. The existing stator winding is designed to have the same Fig.10 and Fig.11 This diagram shows the number of slots in which the unit coils U1 to U16 of the U-phase coil 32U of each of the stator winding 32 in the present embodiment and the conventional stator winding are arranged, and the potential difference between two of the unit coils U1 to U16 arranged in each slot. In the present embodiment, the number of the unit coils U1 to U16 arranged in the slots is the same as Fig.14 The same as in.

[0127] As is apparent from the above discussion, in the stator winding 32 in the present embodiment, the series-connected coil group consisting of the unit coils U1 to U8 is designed to have a reverse connection portion. Similarly, the series-connected coil group consisting of the unit coils U9 to U16 has a reverse connection portion. Therefore, each series-connected coil group has a reduced potential difference between the unit coils arranged in the same slot.

[0128] Although not shown, the V-phase coil 32V, the W-phase coil 32W have the same structure as the above-described U-phase coil 32U. Only one or two of the phase coils 32U, 32V, 32W may be designed to have the above-described structure.

[0129] Second Modification of the First Embodiment

[0130] Next, a second modification of the structure of the stator winding 32 will be described. Similarly to the above-described first embodiment, each of the phase coils 32U, 32V, 32W is composed of sixteen unit coils U1 to U16, V1 to V16, or W1 to W16.

[0131] Fig.17 1 is a developed plan view showing the sequence of steps for joining the unit coils U1 to U16, V1 to V16 or W1 to W16 to each other. Fig.17 With Figure 8 Only the U-phase coil 32U is shown in the same manner.

[0132] For simplicity, referring only to the unit coils U1 to U8 of the U-phase coil 32U, the unit coil U1 is configured in slots 2 and 8. The unit coil U2 is configured in slots 8 and 14. The unit coil U3 is configured in slots 1 and 7. The unit coil U4 is configured in slots 1 and 43. The unit coil U5 is configured in slots 37 and 43. The unit coil U6 is configured in slots 2 and 44. The unit coil U7 is configured in slots 38 and 44. The unit coil U8 is configured in slots 32 and 38.

[0133] The connection portion A1 extends or connects between slot No. 2 and slot No. 8. The connection portion A2 connects between slot No. 7 and slot No. 14. The connection portion A3 connects between slot No. 1 and slot No. 43. The connection portion A4 extends or connects between slot No. 1 and slot No. 43. The connection portion A5 connects between slot No. 37 and slot No. 44. The connection portion A6 connects between slot No. 2 and slot No. 44. The connection portion A7 connects between slot No. 32 and slot No. 38. Between the unit coil U8 and the subsequent unit coil U9, the connection portion A8 connects between slot No. 32 and slot No. 38.

[0134] Each of the unit coils U1 to U8 extends 6 slot pitches. One (or more) of the connecting parts A1 to A7 that connect the unit coils U1 to U8 together is different from each other in slot pitch. Specifically, in this modification, each of the connecting parts A1, A3, A4, A6, A7 is connected between two slots 35 (i.e., two coil sides) located 6 slot pitches away from each other. Each of the connecting parts A2, A5 is connected between two slots 35 located 7 slot pitches away from each other.

[0135] If the number of slots 35 corresponding to the pole pitch (i.e., 6 slot pitches) is defined as "j", each of the unit coils U1 to U8 has coil sides arranged j slot pitches away from each other. Each of the connecting portions A1, A3, A4, A6, A7 is connected between slots 35 arranged j slot pitches away from each other. Each of the connecting portions A4, A5 is connected between slots 35 arranged (j+1) slot pitches away from each other.

[0136] In the order of connection from the U-phase terminal T1, the directions in which the connection portions A1 to A7 of the unit coils U1 to U8 extend circumferentially (ie, the connection directions) are different from each other. Fig.17 The connecting parts A2 to A4 extend in the counterclockwise direction (ie, Fig.17 The connecting portion A5 extends in the clockwise direction. The connecting portions A6 to A7 extend in the counterclockwise direction. Therefore, the unit coils U1 to U8 are turned or folded several times, in other words, the direction in which the unit coils U1 to U8 extend is reversed several times along their orientation until they are wound around the entire circumference of the stator core 31.

[0137] Specifically, the direction or orientation of connection A2 is opposite to the direction or orientation of connection A1. The orientation of connection A5 is opposite to the orientation of connection A4. The orientation of connection A6 is opposite to the orientation of connection A5. Therefore, connections A2, A5, A6 are used as reverse connections.

[0138] Although not described in detail, the unit coils U9 to U16 after the unit coils U1 to U8 have the same arrangement as the unit coils U1 to U8. In short, the connection parts A10, A13, A14 of the connection parts A9 to A15 connecting the unit coils U9 to U16 are used as reverse connection parts. In terms of the relationship with the connection part A8 connecting the last unit coil U8 in the first half group of the unit coils U1 to U16 and the first unit coil U9 in the second half group, the connection part A9 after the connection part A8 is used as a reverse connection part. The connection part A9 is arranged in the slot 35 away from each other by 5 slot pitches.

[0139] Fig.18 3 is a view showing the circumferential positions of the unit coils U1 to U16 of the U-phase coil 32U, and the connection directions of the connection portions A1 to A15 of the U-phase coil 32U. As can be seen from the figure, those of the unit coils U1 to U16 that are relatively close to each other are arranged in the same slot 35, thereby reducing the potential difference between the unit coils U1 to U16.

[0140] exist Fig.17 In the embodiment, at the radially innermost side (i.e., the lower side in the figure) of the stator core 31, each of the connection parts A2, A4, A6, ... is connected between the slots 35 arranged 6 slot pitches or 7 slot pitches away from each other. At the radially outermost side (i.e., the upper side in the figure) of the stator core 31, each of the connection parts A1, A3, A5, A7, ... is connected between the slots 35 arranged 5 slot pitches, 6 slot pitches, or 7 slot pitches away from each other. If the pole pitch is generally defined as j (= 6 slot pitches), each of the connection parts A2, A4, A6, ... on the radially innermost side of the stator core 31 is connected between the slots 35 arranged j or (j+1) slot pitches away from each other. Each of the connection parts A1, A3, A5, A7, ... is connected between the slots 35 arranged j, (j+1), or (j-1) slot pitches away from each other.

[0141] The above-described slot pitches of the connection portions A1 to A15 may alternatively be reversed between the radially outer side and the radially inner side of the stator core 31 .

[0142] Fig.19 3 is a view showing a reduction in the potential difference between the unit coils of the stator winding 32 in this modification and the existing stator winding. The existing stator winding is designed to have the same Fig.10 and Fig.11This diagram shows the number of slots in which the unit coils U1 to U16 of the U-phase coil 32U of each of the stator winding 32 in the present embodiment and the conventional stator winding are arranged, and the potential difference between two of the unit coils U1 to U16 arranged in each slot. In the present embodiment, the number of the unit coils U1 to U16 arranged in the slots is the same as Fig.17 The same as in.

[0143] As is apparent from the above discussion, in this modification, the U-phase coil 32U composed of the unit coils U1 to U16 is designed to have two or more reverse connection portions. This results in a reduction in the potential difference between the unit coils arranged in the same slot.

[0144] Although not shown, the V-phase coil 32V, the W-phase coil 32W have the same structure as the above-described U-phase coil 32U. Only one or two of the phase coils 32U, 32V, 32W may be designed to have the above-described structure.

[0145] Second embodiment

[0146] The stator winding 32 in the second embodiment will be described below, which is different from the first embodiment in that each of the U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W is designed to have a double parallel coil layout. Fig. 20 The double parallel coil layout of the U-phase coil 32U, the V-phase coil 32V, and the W-phase coil 32W is shown.

[0147] like Fig. 20 As clearly shown in the figure, the U-phase coil unit 32U includes two coil groups connected in series: a first coil group G1 connected in series and a second coil group G2 connected in series. The first coil group G1 connected in series consists of eight unit coils: unit coils U11, U12, U13, U14, U15, U16, U17, U18 electrically connected in series with each other. The second coil group G2 connected in series consists of eight unit coils: unit coils U21, U22, U23, U24, U25, U26, U27, U28 electrically connected in series with each other. The first coil group G1 connected in series and the second coil group G2 connected in series are connected in parallel to each other.

[0148] Similarly, the V-phase coil unit 32V includes two coil groups connected in series: a first coil group G1 connected in series and a second coil group G2 connected in series. The first coil group G1 connected in series consists of eight unit coils: unit coils V11, V12, V13, V14, V15, V16, V17, V18 electrically connected in series with each other. The second coil group G2 connected in series consists of eight unit coils: unit coils V21, V22, V23, V24, V25, V26, V27, V28 electrically connected in series with each other. The first coil group G1 connected in series and the second coil group G2 connected in series are connected in parallel with each other. The W-phase coil unit 32W includes two coil groups connected in series: a first coil group G1 connected in series and a second coil group G2 connected in series. The first coil group G1 connected in series consists of eight unit coils: unit coils W11, W12, W13, W14, W15, W16, W17, W18 electrically connected in series with each other. The second series-connected coil group G2 consists of eight unit coils: unit coils W21, W22, W23, W24, W25, W26, W27, W28 electrically connected in series with each other. The first series-connected coil group G1 and the second series-connected coil group G2 are connected in parallel with each other.

[0149] Fig.21 32U is a developed plan view showing the sequence of steps in which the unit coils U11 to U28 of the U-phase coil 32U are joined to each other. Fig.21 With Figure 8 Only the U-phase coil 32U is shown in the same manner.

[0150] For simplicity, referring only to the first series-connected coil group G1 of the U-phase coil 32U, the unit coil U11 is configured in slots 2 and 8. The unit coil U12 is configured in slots 7 and 13. The unit coil U13 is configured in slots 14 and 20. The unit coil U14 is configured in slots 9 and 25. The unit coil U15 is configured in slots 26 and 32. The unit coil U16 is configured in slots 31 and 37. The unit coil U17 is configured in slots 25 and 31. The unit coil U18 is configured in slots 20 and 26.

[0151] The connection portion A11 extends or connects between slot No. 2 and slot No. 7. The connection portion A12 connects between slot No. 13 and slot No. 20. The connection portion A13 connects between slot No. 14 and slot No. 19. The connection portion A14 extends or connects between slot No. 25 and slot No. 32. The connection portion A15 connects between slot No. 26 and slot No. 31. The connection portion A16 connects between slot No. 31 and slot No. 37. The connection portion A17 connects between slot No. 20 and slot No. 25.

[0152] Each of the unit coils U11 to U18 extends 6 slot pitches. One (or more) of the connecting portions A11 to A17 that connect the unit coils U1 to U8 together is different from each other in slot pitch. Specifically, in the present embodiment, each of the connecting portions A11, A13, A15, A17 is connected between two slots 35 (i.e., two coil sides) positioned 5 slot pitches away from each other. The connecting portion A16 is connected between two slots 35 positioned 6 slot pitches away from each other. Each of the connecting portions A12, A14 is connected between two slots 35 positioned 7 slot pitches away from each other.

[0153] If the number of slots 35 corresponding to the pole pitch (i.e., 6 slot pitches) is defined as "j", each of the unit coils U11 to U18 has coil sides arranged away from each other by j slot pitches. Each of the connecting portions A11, A13, A15, A17 is connected between slots 35 arranged away from each other by (j-1) slot pitches. The connecting portion A16 is connected between slots 35 arranged away from each other by j slot pitches. Each of the connecting portions A12, A14 is connected between slots 35 arranged away from each other by (j+1) slot pitches.

[0154] In the order of connection from the U-phase terminal T1, the directions in which the connection portions A11 to A17 of the unit coils U11 to U18 extend circumferentially (ie, the connection directions) are different from each other. Fig.21 The connecting parts A16 to A17 extend in the counterclockwise direction (ie, Fig.21 Therefore, the unit coils U11 to U18 are turned or folded several times, in other words, the direction in which the unit coils U11 to U18 extend is reversed along their orientation until they are wound around the entire circumference of the stator core 31.

[0155] Specifically, the direction in which the connection portion A16 extends from the unit coil U16 to the unit coil U17 is opposite to the direction in which the connection portion A15 extends from the unit coil U15 to the unit coil U16. Therefore, the connection portion A16 is used as a reverse connection portion.

[0156] Although not described in detail, the unit coils U21 to U28 of the second series-connected coil group G2 are opposite in circumferential orientation to the unit coils U11 to U18 of the first series-connected coil group G1 as described above, but the slot spacing of the unit coils U21 to U28 and the connecting portions A18 to A27 is the same as the slot spacing in the first series group G1. In other words, the U-phase coil 32U in the second embodiment includes a first series-connected coil group G1 and a second series-connected coil group G2, each of the coil groups G1, G2 consisting of eight unit coils connected in series to each other. Each of the first series-connected coil group G1 and the second series-connected coil group G2 includes a reverse connection portion.

[0157] Fig. 22 It is a view showing the circumferential positions of the unit coils U11 to U18 of the first series-connected coil group G1 and the unit coils U21 to U28 of the second series-connected coil group G2 of the U-phase coil 32U, and also showing the connection directions of the connection portions A11 to A27 of the U-phase coil 32U.

[0158] like Fig. 22 As can be seen in the figure, in the first series-connected coil group G1, the connection direction of the connection parts A11 to A15 of the U-phase coil 32U is oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. The connection direction of the connection parts A16 to A17 is oriented in a counterclockwise direction. In the second series-connected coil group G2, the connection direction of the connection parts A21 to A25 is oriented in a counterclockwise direction between the U-phase terminal T1 and the neutral point N. The connection direction of the connection parts A26 to A27 is oriented in a clockwise direction. The first series-connected coil group G1 and the second series-connected coil group G2 are respectively wound in the above-mentioned manner to have reverse connection parts, so that those of the unit coils U11 to U28 that are positioned close to the U-phase terminal T1 or the neutral point N are arranged in the same slot 35, thereby avoiding the undesirable increase of the potential difference between the unit coils U11 to U28.

[0159] Each of the first series-connected coil group G1 and the second series-connected coil group G2 occupies an angular range of the stator core 31 that is less than the entire circumference of the stator core 31. The first series-connected coil group G1 and the second series-connected coil group G2 are offset from each other in the circumferential direction of the stator core 31 so that the U-phase coil 32U itself occupies the entire circumference of the stator core 31.

[0160] exist Fig.21In the embodiment of the present invention, at the radially innermost side of the stator core 31 (i.e., the lower side of the stator core 31 as shown in the figure), each of the connection parts A12, A14, A16, ... is connected between the slots 35 arranged 6 slot pitches or 7 slot pitches away from each other. At the radially outermost side of the stator core 31 (i.e., the upper side of the stator core 31 as shown in the figure), each of the connection parts A11, A13, A15, A17, ... is connected between the slots 35 arranged 5 slot pitches away from each other. If the pole pitch is generally defined as j (=6 slot pitches), each of the connection parts A12, A14, A16, ... on the radially innermost side of the stator core 31 is connected between the slots 35 arranged j or (j+1) slot pitches away from each other. Each of the connection parts A11, A13, A15, A17, ... is connected between the slots 35 arranged (j-1) slot pitches away from each other.

[0161] The above-mentioned slot pitches of the connection portions A11 to A17, A21 to A27 may alternatively be reversed between the radially outer side and the radially inner side of the stator core 31. Specifically, the connection portions on the radially innermost side of the stator core 31 may be connected between slots 35 arranged away from each other by (j-1) slot pitches. The connection portions on the radially outermost side of the stator core 31 may be connected between slots 35 arranged away from each other by j or (j+1) slot pitches.

[0162] Although not shown, the V-phase coil 32V, the W-phase coil 32W have the same structure as the U-phase coil 32U described above. Only one or two of the phase coils 32U, 32V, 32W may be designed to have the above-described structure.

[0163] The phase coils 32U, 32V, 32W, each including two parallel coil arrays (i.e., the first series-connected coil group G1 and the second series-connected coil group G2), are preferably designed to have ends arranged at positions close to the phase terminals T1, T2, or T3 or the neutral point N and dispersedly and evenly located on the periphery of the stator core 31. It is also recommended that the phase coils 32U, 32V, 32W be arranged to satisfy the relationship of [480° / (the number of pole pairs×the number of arrays of unit coils connected in parallel to each other)]. This reduces the potential difference between the corresponding adjacent two of the phase coils 32U, 32V, 32W.

[0164] The rotary electric machine 10 in the present embodiment is designed to have phase coils 32U, 32V, 32W, and as described above, each of the phase coils 32U, 32V, 32W includes two coil arrays connected in parallel: a first series-connected coil group G1 and a second series-connected coil group G2 electrically connected in parallel to each other. Each of the first series-connected coil group G1 and the second series-connected coil group G2 is wound to occupy an angular range of the stator core 31 that is less than the entire circumference of the stator core 31. The first series-connected coil group G1 and the second series-connected coil group G2 are offset from each other in the circumferential direction of the stator core 31, thereby facilitating easy creation of a reverse connection portion to reverse the connection direction of the unit coils.

[0165] Modification of the Second Embodiment

[0166] A modification of the stator core 31 equipped with the phase coils 32U, 32V, 32W each of which includes two coil arrays connected in parallel will be described below.

[0167] Figure 23(a) to Figure 23(c) It is a view showing the circumferential positions of the unit coils U11 to U18 of the first series-connected coil group G1 and the unit coils U21 to U28 of the second series-connected coil group G2 of the U-phase coil 32U, and also showing the connection directions of the connection portions A11 to A27 of the U-phase coil 32U.

[0168] In the variation shown in FIG. 23( a), in the first series-connected coil group G1, the connection direction of the connection portion A11 is oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. The connection directions of the connection portions A12 to A17 are oriented in a counterclockwise direction. In the second series-connected coil group G2, the connection direction of the connection portion A21 is oriented in a counterclockwise direction between the U-phase terminal T1 and the neutral point N. The connection directions of the connection portions A22 to A27 are oriented in a clockwise direction. The connection portions A12, A22 are used as reverse connection portions.

[0169] In the variation shown in FIG. 23( b), in the first series-connected coil group G1, the connection direction of the connection portion A11 is oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. The connection directions of the connection portions A12 to A15 are oriented in a counterclockwise direction. The connection directions of the connection portions A16 to A17 are oriented in a clockwise direction again. In the second series-connected coil group G2, the connection direction of the connection portion A21 is oriented in a counterclockwise direction between the U-phase terminal T1 and the neutral point N. The connection directions of the connection portions A22 to A25 are oriented in a clockwise direction. The connection directions of the connection portions A26 to A27 are oriented in a counterclockwise direction again. The connection portions A12, A16, A22, and A26 are used as reverse connection portions.

[0170] In each variation in Figures 23(a) and 23(b), the first series-connected coil group G1 and the second series-connected coil group G2 differ from each other in the positions of the phase terminal and the neutral point. The circumferential direction in which the unit coils of the first series-connected coil group G1 extend from the U-phase terminal to the neutral point is opposite to the circumferential direction in which the unit coils of the second series-connected coil group G2 extend from the U-phase terminal to the neutral point.

[0171] In the variation shown in FIG. 23( c ), in the first series-connected coil group G1, the connection direction of the connection portion A11 is oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. The connection direction of the connection portion A12 is oriented in a counterclockwise direction. The connection directions of the connection portions A13 to A15 are oriented in a clockwise direction. The connection direction of the connection portion A16 is oriented in a counterclockwise direction. The connection direction of the connection portion A17 is oriented in a clockwise direction.

[0172] In the second series-connected coil group G2 of FIG. 23( c), the connection direction of the connection portion A21 is oriented in a clockwise direction between the U-phase terminal T1 and the neutral point N. The connection direction of the connection portion A22 is oriented in a counterclockwise direction. The connection directions of the connection portions A23 to A25 are oriented in a clockwise direction. The connection direction of the connection portion A26 is oriented in a counterclockwise direction. The connection direction of the connection portion A27 is oriented in a clockwise direction again. The connection portions A12, A13, A16, A17 of the first series-connected coil group G1 and the connection portions A22, A23, A26, A27 of the second series-connected coil group G2 are used as reverse connection portions.

[0173] 23(c) differ from each other in the positions of the phase terminals and the neutral point. The circumferential orientations of the unit coils of the first and second series-connected coil groups G1 and G2 are substantially the same.

[0174] exist Figure 23(a) to Figure 23(c) In a variation of this, the first series-connected coil group G1 and the second series-connected coil group G2 are respectively wound in the above-mentioned manner to have reverse connection portions, so that those of the unit coils U11 to U28 positioned close to the U-phase terminal T1 or the neutral point N are configured in the same slot 35, thereby avoiding an undesirable increase in the potential difference between the unit coils U11 to U28.

[0175] exist Figure 23(a) to Figure 23(c) In a variation of Fig.21 and Fig. 22, each of the first series-connected coil group G1 and the second series-connected coil group G2 is wound to occupy an angular range of the stator core 31 that is less than the entire circumference of the stator core 31. The first series-connected coil group G1 and the second series-connected coil group G2 are offset from each other in the circumferential direction of the stator core 31 so that the U-phase coil 32U itself occupies the entire circumference of the stator core 31.

[0176] Although not shown, the V-phase coil 32V, the W-phase coil 32W have the same structure as the above-described U-phase coil 32U. Only one or two of the phase coils 32U, 32V, 32W may be designed to have the above-described structure.

[0177] Third embodiment

[0178] Unlike the first embodiment, the stator winding 32 in the third embodiment is designed to have phase coils 32U, 32V, 32W, each of which is composed of four coil arrays connected in parallel. Fig.24 FIG. 2 shows the coil connection of the stator winding 32 in this embodiment. Specifically, Fig.24 As can be seen in the figure, the U-phase coil 32U includes four series-connected coil groups G1, G2, G3, and G4 electrically connected in parallel to each other. The series-connected coil group G1 consists of four unit coils: unit coils U11, U12, U13, and U14. Similarly, the series-connected coil group G2 consists of unit coils U21, U22, U23, and U24. The series-connected coil group G3 consists of unit coils U31, U32, U33, and U34. The series-connected coil group G4 consists of unit coils U41, U42, U43, and U44. The V-phase coil 32V and the W-phase coil 32W have the same structure as the U-phase coil 32U, and their detailed description will be omitted here.

[0179] 25( a ) and 25 ( b ) are views showing the circumferential positions of the unit coils U11 to U44 of the series-connected coil group G1 to G4 of the U-phase coil 32U, and also showing the connection directions of the connection portions A11 to A43 of the U-phase coil 32U.

[0180] Figure 25 (a) shows the first type of stator winding 32 in the third embodiment. Specifically, each of the coil groups G1 to G4 connected in series has two reverse connection parts. The grouped reverse connection parts of the coil groups G1 to G4 connected in series are arranged at equal intervals away from each other along the circumferential direction of the stator core 31. More specifically, in the coil group G1 connected in series, the connection direction of the connection parts A11 and A13 is oriented in the clockwise direction. The connection direction of the connection part A12 is oriented in the counterclockwise direction. The connection parts A12 and A13 are used as reverse connection parts. The coil groups G2, G3, and G4 connected in series have the same structure as the coil group G1 connected in series.

[0181] Each of the coil groups G1 to G4 connected in series has two reverse connections. This allows those of the unit coils U11 to U44 located near the U-phase terminal T1 or the neutral point N to be arranged in the same slot 35, thereby minimizing the undesirable increase in the potential difference between the unit coils U11 to U44.

[0182] FIG25( b) shows the second type of stator winding 32 in the third embodiment. Specifically, two of the coil groups G1 to G4 connected in series, namely the coil groups G1 and G2 connected in series, each have two reverse connection parts. The connection part A12 of the coil group G1 connected in series and the connection part A32 of the coil group G2 connected in series are used as reverse connection parts. The other coil groups G3 and G4 connected in series do not have reverse connection parts.

[0183] As is apparent from the above discussion, the U-phase coil 32U includes a series-connected coil group equipped with a reverse connection portion (i.e., the series-connected coil group G1, G2) and a series-connected coil group not equipped with a reverse connection portion (i.e., the series-connected coil group G3, G4), but the U-phase coil 32U is designed to have at least two reverse connection portions so that the unit coils U11 to U44 that are located closer to the U-phase terminal T1 or the neutral point N are arranged in the same slot 35, which reduces the potential difference between the unit coils U11 to U44.

[0184] In the stator winding 32 of Figures 25(a) and 25(b), each of the coil groups G1 to G4 connected in series is wound to occupy an angular range of the stator core 31 that is less than the entire circumference of the stator core 31. The coil groups G1 to G4 connected in series are offset from each other in the circumferential direction of the stator core 31 so that the U-phase coil 32U itself occupies the entire circumference of the stator core 31.

[0185] Although not shown, the V-phase coil 32V, the W-phase coil 32W have the same structure as the above-described U-phase coil 32U. Only one or two of the phase coils 32U, 32V, 32W may be designed to have the above-described structure.

[0186] Fourth embodiment

[0187] The rotating electric machine 10 in each of the above-described embodiments is configured such that the number of magnetic poles is eight, the number of pole pairs is four, and the number of slots is forty-eight, but it may be designed in a different manner. The rotating electric machine 10 in the fourth embodiment is designed such that the number of magnetic poles is twelve, the number of pole pairs is six, and the number of slots is seventy-two. The rotating electric machine 10 in this embodiment has substantially the same structure as the first embodiment except for the number of magnetic poles and the number of slots 35. Similar to the above-described embodiments, the stator winding 32 is made of conductor segments.

[0188] Fig. 26 (a) and Fig. 26 (b) show the structure of the stator 30 in which seventy-two slots are formed. Fig. 26 (a) is a perspective view showing a welded portion of the conductor segment 50 located at a first end (i.e., coil end 37) of the stator 30. Fig. 26 (b) is a perspective view showing a bent portion of the conductor segment 50 located at a second end (i.e., coil end 36) of the stator 30 opposite to the first end in the axial direction of the stator 30.

[0189] The U-phase coil 32U, V-phase coil 32V, and W-phase coil 32W of the stator 30 are arranged on the coil end 37, and their ends (hereinafter also referred to as winding ends) are close to the U-phase terminal, V-phase terminal, and W-phase terminal indicated by "U", "V", and "W" in the figure. Fig.24 As shown, each of the phase coils 32U, 32V, 32W is designed to have four coil arrays connected in parallel, and therefore has eight winding ends: four close to a corresponding one of the U-phase terminal, the V-phase terminal, the W-phase terminal, and four close to the neutral point. The winding ends of each of the phase coils 32U, 32V, 32W close to the neutral point N are connected together using a neutral line 38.

[0190] Each of the phase coils 32U, 32V, 32W includes four parallel-connected coil arrays (i.e., series-connected coil groups G1, G2, G3, G4), which are similar in structure to the phase coils 32U, 32V, 32W except for the number of unit coils. Fig.24The same as shown in . Specifically, each of the series-connected coil groups of each of the phase coils 32U, 32V, 32W includes six coil units electrically connected in series with each other. More specifically, the U-phase coil 32U includes series-connected coil groups G1, G2, G3, G4 connected in parallel with each other. The series-connected coil group G1 consists of six unit coils U11 to U16. Similarly, the series-connected coil group G2 consists of six unit coils U21 to U26. The series-connected coil group G3 consists of six unit coils U31 to U36. The series-connected coil group G4 consists of six unit coils U41 to U46.

[0191] Fig. 27 3 is a plan view showing the sequence of steps (ie, the sequence of joining) in which a plurality of unit coils are joined together in the stator core 31. For convenience, Fig. 27 Only the series-connected coil group G1 (ie, unit coils U11 to U16) of the U-phase coil 32U is shown. Fig. 27 , the slots 35 of the stator core 31 are numbered 1 to 72. The joining order is indicated by arrows starting from the U-phase terminal as a starting point. The arrows on the bend 52 side of the conductor segment 50 are indicated by solid lines. The arrows on the welding portion side of the conductor segment 50 are indicated by dotted lines.

[0192] exist Fig. 27 , the unit coil U11 is arranged in slot No. 3 and slot No. 9. The unit coil U12 is arranged in slot No. 70 and slot No. 4. The unit coil U13 is arranged in slot No. 63 and slot No. 69. The unit coil U14 is arranged in slot No. 58 and slot No. 64. The unit coil U15 is arranged in slot No. 64 and slot No. 70. The unit coil U16 is arranged in slot No. 69 and slot No. 3. The unit coils U11 to U16 extend 6 slot pitches in the circumferential direction of the stator core 31. The connecting portion A11 is connected between slot No. 70 and slot No. 3, which are arranged 5 slot pitches away from each other. The connecting portion A12 is connected between slot No. 69 and slot No. 4, which are arranged 7 slot pitches away from each other. The connecting portion A13 is connected between slot No. 58 and slot No. 63, which are arranged 5 slot pitches away from each other. The connecting portion A14 is connected between slot No. 64 and slot No. 70, which are arranged 6 slot pitches away from each other. The connection portion A15 is connected between the slot No. 64 and the slot No. 69 which are arranged away from each other by 5 slot pitches.

[0193] As is apparent from the above discussion, the connections A11, A13, A15 on the radially innermost side of the stator core 31 extend for 5 slot pitches respectively. The connections A12, A14 on the radially outermost side of the stator core 31 extend for 6 or 7 slot pitches. The above slot pitches of the connections A11 to A15 may alternatively be reversed between the radially outer side and the radially inner side of the stator core 31. Fig. 27, the conductor segment 50 connected to the U-phase terminal of the unit coil U11 is represented by “ A0 ”.

[0194] In the present embodiment, the connection portions whose slot pitches are different from each other are provided by differentiating the size of the turning portion 52 of the conductor segment 50 along the circumferential direction of the stator core 31. Specifically, FIG. 28(a), FIG. 28(b), and FIG. 28(c) show three types of conductor segments 50 represented by 50A, 50B, and 50C. FIG. 28(a) shows a conductor segment 50A for 5 slot pitches. FIG. 28(b) shows a conductor segment 50B for 6 slot pitches. FIG. 28(c) shows a conductor segment 50C for 7 slot pitches.

[0195] Figure 28(a) to Figure 28(c) The conductor segments 50A to 50C in the embodiment have the same total length. The bends 52 of the conductor segments 50A to 50C have the same total length, but have different dimensions La, Lb, Lc (hereinafter also referred to as circumferential dimensions) in the circumferential direction of the stator core 31 (i.e., transverse dimensions, such as Figure 28(a) to Figure 28(c) , in other words, the coil side portions, i.e., the intervals between the straight portions 51 of the conductor segments 50A to 50C) are different in construction from each other. Specifically, in the conductor segments 50A, 50B, 50C, a portion of the turn portion 52 extending away from the straight portion 51 and a line extending perpendicular to the axial direction of the stator core 31 (i.e., the axial end surface of the stator core 31) form different angles. As shown in FIG. 28(a), FIG. 28(b), and FIG. 28(c), the conductor segments 50A, 50B, 50C have an angle of θa>θb>θc. This results in different circumferential dimensions La, Lb, Lc (La<Lb<Lc) of the turn portion 52 of the conductor segments 50A, 50B, 50C without changing the total length of the turn portion 52. Such a geometric shape of the turn portion 52 enables the coil end of the conductor segment 50 to be reduced.

[0196] The conductor segment 50A in FIG28( a) is used as each of the connection portions A11, A13, A15 arranged at 5 slot pitches on the radially innermost side of the stator core 31. The conductor segments 50B, 50C in FIG28( b) and FIG28( c) are used as the connection portions A12, A14 arranged at 6 and 7 slot pitches on the radially outermost side of the stator core 31.

[0197] Fig. 29 (a) and Fig. 29 (b) are enlarged views showing the coil end 37 of the stator winding 32 located at the end of the stator core 31 where the turn portion 52 is arranged. Fig. 29 (a) shows the coil end 37 viewed from the radial inside of the stator core 31. Fig. 29 (b) shows the coil end 37 viewed from the radial outside of the stator core 31. As can be seen in the figure, each conductor segment 50 has a portion (hereinafter also referred to as an interference avoider) bent in the radial or axial direction of the stator core 31 so as to eliminate physical interference between the conductor segments 50.

[0198] The conductor segments 50 arranged at the end of the stator core 31 provided with the turn portion 52 include connection portions for different slot pitches, while the conductor segments 50 arranged at the end of the stator core 31 provided with the welding portion of the conductor segments 50 and used as connection portions are all provided for 6 slot pitches. This facilitates easy welding of the ends of the conductor segments 50, thereby improving productivity of the stator winding 32.

[0199] Refer again Fig. 27 , for example, the U-phase terminal indicated by "U" of the U-phase coil 32U is connected to the conductor segment 50 configured in slot No. 3. The neutral point N is connected to the conductor segment 50 configured in slot No. 69. Arranged next to slot No. 3 in the clockwise direction is the unit coil U11. Arranged next to slot No. 3 in the counterclockwise direction are the unit coils U12 and U16. Arranged next to slot No. 69 in the clockwise direction are the unit coils U12 and U16. Arranged next to slot No. 69 in the counterclockwise direction are the unit coils U13 and U15. In other words, each of the series-connected coil groups G1, G2, G3, and G4 of the U-phase coil 32U is composed of unit coils, some of which are arranged on circumferentially opposite sides of each of the U-phase terminal and the neutral point N. This promotes a reduction in the potential difference between the coil units of the stator winding 32.

[0200] Fig.30 1 is a view showing the circumferential positions of the unit coils U11 to U16 of the series-connected coil group G1, the unit coils U21 to U26 of the series-connected coil group G2, the unit coils U31 to U36 of the series-connected coil group G3, and the unit coils U41 to U46 of the series coil unit G4 of the U-phase coil 32U, and also showing the connection direction of the connection portion of the U-phase coil 32U. Each of the series-connected coil groups G1 to G4 is equipped with a connection portion including a reverse connection portion for reversing the connection direction between two adjacent unit coils in accordance with the engagement order.

[0201] Specifically, in the coil group G1 connected in series, the direction or orientation of the connection portion A14 extending from the unit coil U14 to the unit coil U15 is opposite to the direction or orientation of the connection portion A13 extending from the unit coil U13 to the unit coil U14. Therefore, the connection portion A14 is used as a reverse connection portion. The same is true for the coil groups G2 to G4 connected in series. The connection portion A24 of the coil group G2 connected in series is used as a reverse connection portion. The connection portion A34 of the coil group G3 connected in series is used as a reverse connection portion. The connection portion A44 of the coil group G4 connected in series is used as a reverse connection portion. This makes the unit coils of each of the coil groups G2 to G4 connected in series, which are close to each other starting from the U phase terminal in the order of engagement, configured in the same slot, thereby avoiding the undesirable increase in the potential difference between the unit coils U11 to U44. The V phase coil 32V and the W phase coil 32W have the same structure as the U phase coil 32U, and their detailed description will be omitted here.

[0202] Fig.31 and Fig.32 Shows Fig. 27 A variation of the stator winding 32 is shown in FIG.

[0203] The following discussion will refer only to the variants and Fig. 27 The difference between the stator winding 32.

[0204] exist Fig.31 In a variation of , unit coil U11 is configured in slot No. 70 and slot No. 4. Unit coil U12 is configured in slot No. 3 and slot No. 9. Unit coil U13 is configured in slot No. 9 and slot No. 15. Unit coil U14 is configured in slot No. 4 and slot No. 10. Unit coil U15 is configured in slot No. 10 and slot No. 16. Unit coil U16 is configured in slot No. 15 and slot No. 21. Each of unit coils U11 to U16 extends 6 slot pitches. Connecting portion A11 extends or connects between slot No. 70 and slot No. 3, which are arranged 5 slot pitches away from each other. Connecting portion A12 is connected between slot No. 9 and slot No. 15, which are arranged 6 slot pitches away from each other. Connecting portion A13 is connected between slot No. 4 and slot No. 9, which are arranged 5 slot pitches away from each other. Connecting portion A14 is connected between slot No. 10 and slot No. 16, which are arranged 6 slot pitches away from each other. The connection portion A15 is connected between the No. 10 slot and the No. 15 slot which are arranged away from each other by 5 slot pitches.

[0205] exist Fig.31In a variation of, the orientation or direction of the connection portion A13 extending from the unit coil U13 to the unit coil U14 is opposite to the orientation or direction of the connection portion A12 extending from the unit coil U12 to the unit coil U13. The direction of the connection portion A14 extending from the unit coil U14 to the unit coil U15 is opposite to the direction of the connection portion A13 extending from the unit coil U13 to the unit coil U14. Therefore, the connection portions A13, A14 are used as reverse connection portions. Although not described in detail, the same applies to the other coil groups G2 to G4 connected in series. The above arrangement makes those of the unit coils of each of the coil groups G1 to G4 connected in series that are close to each other starting from the U-phase terminal in the order of engagement configured in the same slot, thereby avoiding the undesirable increase in the potential difference between the unit coils U11 to U44. The V-phase coil 32V and the W-phase coil 32W have the same structure as the U-phase coil 32U, and their detailed description will be omitted here.

[0206] Except for the position of the U-phase terminal of the stator winding 32 and the portion from which the neutral point N extends, Fig.32 The variation shown in FIG. 1 is similar to the one shown in FIG. 1 in terms of the layout of the unit coils U11 to U16. Fig.31 The same as in.

[0207] Other Implementations

[0208] The above-described embodiment may be modified in the following manner.

[0209] The stator core 31 may be designed to have two or more slots for each pole and each phase, for example, four or more slots.

[0210] The rotating electric machine 10 may alternatively be designed as an outer rotor type. The rotating electric machine 10 may alternatively be used for various types of moving objects or electric devices for commercial or domestic use, rather than being used as an electric motor for propelling a vehicle.

Claims

1. A rotating electrical machine (10), comprising: A stator (30) comprising a stator core (31) in which a plurality of slots (35) arranged adjacent to each other in a circumferential direction of the stator core are formed, and a stator winding (32) equipped with a plurality of phase coils (32U, 32V, 32V) wound in the slots; and A rotor (20) is configured to face the stator and has a plurality of magnetic poles, the plurality of magnetic poles being arranged adjacent to each other along a circumferential direction of the rotor, wherein The phase coils are connected to respective phase terminals (T1, T2, T3) at first ends of the phase coils and to a neutral point (N) at second ends of the phase coils; Each of the phase coils includes a plurality of unit coils (41) which are connected in series with each other in a joining order starting from a corresponding one of the phase terminals and are arranged away from each other by a given slot spacing between a corresponding one of the phase terminals and the neutral point, and the unit coils are connected together using a connecting conductor (42). The connecting conductors include a first connecting conductor connecting an i-th unit coil counted from a corresponding one of the phase terminals to an i+1-th unit coil in a bonding order, and a second connecting conductor connecting an i+1-th unit coil counted from a corresponding one of the phase terminals to an i+2-th unit coil in a bonding order, and Each of the phase coils includes more than two reverse connecting conductors, each of which is provided by the second connecting conductor and is oriented so that in the circumferential direction of the stator core, the direction in which the second connecting conductor extends from the i+1th unit coil to the i+2th unit coil is opposite to the direction in which the first connecting conductor extends from the i-th unit coil to the i+1th unit coil.

2. The rotating electrical machine according to claim 1, characterized in that Each of the phase coils includes a plurality of series-connected coil groups into which the unit coil is divided, the series-connected coil groups are connected to each other in series or in parallel, and each of the series-connected coil groups is provided with the reverse-connection conductor.

3. The rotating electrical machine according to claim 2, characterized in that Each of the series-connected coil groups includes four unit coils connected in series with each other, The connecting conductor includes a first connecting portion, a second connecting portion, and a third connecting portion, the first connecting portion being connected between a first unit coil and a second unit coil, the second connecting portion being connected between the second unit coil and a third unit coil, the third connecting portion being connected between the third unit coil and a fourth unit coil, the first unit coil being the first unit coil among the unit coils of each of the series-connected coil groups counted in a coupling sequence from a corresponding one of the phase terminals, the second unit coil being the second unit coil among the unit coils counted in a coupling sequence from a corresponding one of the phase terminals, the third unit coil being the third unit coil among the unit coils counted in a coupling sequence from a corresponding one of the phase terminals, and the fourth unit coil being the fourth unit coil among the unit coils counted in a coupling sequence from a corresponding one of the phase terminals, In the circumferential direction of the stator core, the direction in which the second connection portion extends from the second unit coil to the third unit coil is opposite to the direction in which the first connection portion extends from the first unit coil to the second unit coil. In the circumferential direction of the stator core, the direction in which the third connection portion extends from the third unit coil to the fourth unit coil is opposite to the direction in which the second connection portion extends, and The second connection portion and the third connection portion are used as the reverse connection conductor.

4. The rotating electrical machine according to claim 2 or 3, characterized in that: Each of the phase coils includes two or more series-connected coil groups connected in parallel to each other and occupies the entire circumference of the stator core, Each of the series-connected coil groups of each of the phase coils occupies an angular extent of the stator core that is less than the entire circumference of the stator core, and The series-connected coil groups are offset from each other in a circumferential direction of the stator core.

5. The rotating electrical machine according to any one of claims 1 to 4, characterized in that Each of the phase coils is composed of m unit coils connected in series to one another between a corresponding one of the phase terminals and the neutral point, and wherein the two or more reverse-connecting conductors are arranged over the entire circumference of the stator core.

6. The rotating electrical machine according to any one of claims 1 to 5, characterized in that 2k slots are formed in the stator core for each pole and each phase, where k is a natural number, The unit coils are made of conductors wound in the form of overlapping windings, and coil sides of the unit coils are arranged in the slots in the form of multiple layers stacked in a radial direction of the stator core, If one pole pitch is defined as j slot pitches, the connecting conductor extends for at least one of j slot pitches, j-1 slot pitches, and j+1 slot pitches in the circumferential direction of the stator core.

7. The rotating electrical machine according to claim 6, characterized in that Each of the unit coils is made of a plurality of conductor segments (50), each of the conductor segments includes a pair of straight portions (51) and a bend portion (52) connecting the straight portions together, the straight portions of the conductor segments being joined together in the form of overlapping windings, and Each of the connecting conductors is connected between redundant portions (53) of the straight portions of corresponding two of the unit coils which are sequentially arranged adjacent to each other in a bonding order.

8. The rotating electrical machine according to any one of claims 1 to 7, characterized in that The connecting conductors are alternately arranged on a first radial side and a second radial side of the stator core in a joining order of the unit coils, If one pole pitch is defined as j slot pitches, the connecting conductor on the first radial side of the stator core extends for j slot pitches in the circumferential direction of the stator core, and The connecting conductor on the second radial side of the stator core extends for j±1 slot pitches in the circumferential direction of the stator core.

9. The rotating electrical machine according to any one of claims 1 to 7, characterized in that The connecting conductors are alternately arranged on a first radial side and a second radial side of the stator core in a joining order of the unit coils, If one pole pitch is defined as j slot pitches, the connecting conductor on the first radial side of the stator core extends for j slot pitches and j+1 slot pitches in the circumferential direction of the stator core, and The connecting conductor on the second radial side of the stator core extends for j-1 slot pitches in the circumferential direction of the stator core.

10. The rotating electrical machine according to any one of claims 1 to 7, characterized in that The connecting conductors are alternately arranged on a first radial side and a second radial side of the stator core in a joining order of the unit coils, If one pole pitch is defined as j slot pitches, the connecting conductor on the first radial side of the stator core extends for j slot pitches and j+1 slot pitches in the circumferential direction of the stator core, and The connecting conductor on the second radial side of the stator core extends by j slot pitches and j±1 slot pitches in the circumferential direction of the stator core.

11. The rotating electrical machine according to any one of claims 1 to 10, characterized in that The phase coils are arranged to have a given phase difference between ends leading to the phase terminals, the given phase difference satisfying the relationship of [480° / (the number of pole pairs×the number of arrays of the unit coils connected in parallel to each other)].

Images