STATOR ARRANGEMENT WITH WINDING SETS FEATURING HAIRNEEDLES MADE OF MULTIPLE LAYER HAIRNEEDLE LAYERS

Abstract

Stator arrangement (16) comprising: a plurality of stator slots (20) defining multiple slot layers (22A, ..., 22F); a plurality of hairpins (24), each having a first leg (26) positioned in one of the multiple slot layers (22A, ..., 22F) and a second leg (28) positioned in another of the multiple slot layers (22A, ..., 22F), each of the plurality of hairpins (24) being configured to allow current flow from the respective first leg (26) to the respective second leg (28); wherein the plurality of hairpins (24) is subdivided into multiple hairpin layers (54A, ..., 54F); wherein the plurality of hairpins (24) forms multiple winding sets (61, 62, 63, 64), each of the multiple winding sets (61, 62, 63, 64) at least partially contains the plurality of hairpins (24) from at least two of the multiple hairpin layers (54A, ..., 54F);wherein: the multiple hairpin layers (54A, ..., 54F) comprise first, second, third, fourth, fifth and sixth hairpin layers (54A, ..., 54F); the multiple winding sets (61, 62, 63, 64) comprise first, second, third and fourth winding sets (61, 62, 63, 64); and the multiple groove layers (22A, ..., 22F) comprise first, second, third, fourth, fifth and sixth groove layers (22A, ..., 22F); wherein: the first hairpin layer (54A) is defined by the plurality of hairpins (24) whose respective first leg (26A) is located in the first groove layer (22A) and whose respective second leg (28A) is located in the second groove layer (22B); the second hairpin layer (54B) is defined by the plurality of hairpins (24) whose respective first leg (26B) is located in the second groove layer (22B) and whose respective second leg (28B) is located in the first groove layer (22A);the third hairpin layer (54C) is defined by the plurality of hairpins (24) whose respective first leg (26C) is located in the third groove layer (22C) and whose respective second leg (28C) is located in the fourth groove layer (22D); the fourth hairpin layer (54D) is defined by the plurality of hairpins (24) whose respective first leg (26D) is located in the fourth groove layer (22D) and whose respective second leg (28D) is located in the third groove layer (22C); the fifth hairpin layer (54E) is defined by the plurality of hairpins (24) whose respective first leg (26E) is located in the fifth groove layer (22E) and whose respective second leg (28E) is located in the sixth groove layer (22F);the sixth hairpin layer (54F) is defined by the plurality of hairpins (24) whose respective first leg (26F) is located in the sixth groove layer (22F) and whose respective second leg (28F) is located in the fifth groove layer (22E); wherein: the first winding set (61) comprises a combination of the plurality of hairpins (24) from the first (54A) and third hairpin layers (54C); the second winding set (62) comprises a combination of the plurality of hairpins (24) from the second (54B) and fourth hairpin layers (54D); the third winding set (63) comprises a combination of the plurality of hairpins (24) from the fifth (54E) and third hairpin layers (54C); and the fourth winding set (64) comprises a combination of the multitude of hairpins (24) from the sixth (54F) and fourth hairpin layers (54D);wherein: the first winding set (61) comprises 12 from the plurality of hairpins (24) from the first hairpin layer (54A) connected in series with 6 from the plurality of hairpins (24) from the third hairpin layer (54C); the second winding set (62) comprises 12 from the plurality of hairpins (24) from the second hairpin layer (54B) connected in series with 6 from the plurality of hairpins (24) from the fourth hairpin layer (54D); the third winding set (63) comprises 12 from the plurality of hairpins (24) from the fifth hairpin layer (54E) connected in series with 6 from the plurality of hairpins (24) from the third hairpin layer (54C); and the fourth winding set (64) comprises 12 from the plurality of hairpins (24) from the sixth hairpin layer (54F) connected in series with 6 from the plurality of hairpins (24) from the fourth hairpin layer (54D).

Description

TECHNICAL AREA The disclosure relates generally to a stator arrangement in an electrical machine and in particular to the winding configuration in a stator arrangement with bar windings. BACKGROUND An electric machine comprises a rotor assembly that is rotatable relative to a stator assembly. The stator assembly generally includes a number of stator windings inserted into slots in the stator assembly. A bar-winding stator assembly is sometimes used in electric machines to improve thermal efficiency and the overall power output of the machine. The number of turns or windings in a bar-winding stator assembly can generally only be changed in discrete steps corresponding to specific configurations. US 2006 / 0033394A1 discloses a stator arrangement with a sequentially assembled segmented coil in which conductor segments are arranged in six slot layers. A phase winding is composed of different coil types, each of which consists of conductor segments of a single, assigned type. DE 60311045T2 discloses a stator arrangement in which a phase winding is formed by the alternating connection of wave winding and loop winding segments. Within a winding set, different segment types are combined, connecting different pairs of slot layers. SUMMARY A stator arrangement comprises a plurality of stator slots defining multiple slot layers. The arrangement includes a plurality of electrical conductors or hairpins, each having a first leg positioned in one of the multiple slot layers and a second leg positioned in another of the multiple slot layers. In a bar-winding design, the electrical conductor is typically referred to by those skilled in the art as a "hairpin" and will be referred to as such in this description. The plurality of hairpins is subdivided into multiple hairpin layers. Each of the hairpins (the term "hairpins" is intended to denote "the plurality of hairpins") is configured to allow current flow from its respective first leg to its respective second leg. The hairpins form several winding sets, such as a first, second, third, and fourth winding set. Each winding set includes at least part of the hairpins of at least two of the multiple hairpin layers. The multiple slot layers include the first, second, third, fourth, fifth, and sixth slot layers. The multiple hairpin layers include the first, second, third, fourth, fifth, and sixth hairpin layers. At least one of the hairpin layers is shared by two winding sets. This stator winding arrangement improves the flexibility of the bar-winding stator arrangement by allowing for additional turn counts or configurations. The first set of wraps comprises a combination of hairpins from the first and third layers. The second set of wraps comprises a combination of hairpins from the second and fourth layers. The third set of wraps comprises a combination of hairpins from the fifth and third layers. The fourth set of wraps comprises a combination of hairpins from the sixth and fourth layers. Therefore, the third layer is shared by the first and third sets of wraps, and the fourth layer is shared by the second and fourth sets. The first set of wraps consists of 12 hairpins from the first layer, connected in a row with 6 hairpins from the third layer. The second set of wraps consists of 12 hairpins from the second layer, connected in a row with 6 hairpins from the fourth layer. The third set of wraps consists of 12 hairpins from the fifth layer, connected in a row with 6 hairpins from the third layer. The fourth set of wraps consists of 12 hairpins from the sixth layer, connected in a row with 6 hairpins from the fourth layer. The first hairpin layer is defined by hairpins with their respective first limb in the first groove layer and their respective second limb in the second groove layer. The second hairpin layer is defined by hairpins with their respective first limb in the second groove layer and their respective second limb in the first groove layer. The third hairpin layer is defined by hairpins with their respective first limb in the third groove layer and their respective second limb in the fourth groove layer. The fourth hairpin layer is defined by hairpins with their respective first limb in the fourth groove layer and their respective second limb in the third groove layer. The fifth hairpin layer is defined by hairpins with their respective first limb in the fifth groove layer and their respective second limb in the sixth groove layer.The sixth hairpin layer is defined by hairpins with their respective first leg in the sixth groove layer and their respective second leg in the fifth groove layer. Each of the hairpins can be a short-pitch coil or a full-pitch coil. The short-pitch and full-pitch coils are configured to extend over a first and second number, respectively, of the plurality of stator slots, such that the first number is smaller than the second. In one example, the first and second numbers are 8 and 9. In the first embodiment, the third and fourth hairpin layers can contain more short-pitch coils than each of the first, second, fifth, and sixth hairpin layers. For example, the third and fourth hairpin layers can each contain at least four short-pitch coils, while the first, second, fifth, and sixth hairpin layers can each contain at least two short-pitch coils. The first, second, third, and fourth winding sets can each define an identical number of multiple phases. In one embodiment, the multiple phases are exactly three phases; the plurality of stator slots comprises exactly 72 slots; and the stator defines 8 poles. In another embodiment, the first and second winding sets each comprise a combination of the plurality of hairpins from the first, third, and fifth hairpin layers. The third and fourth winding sets each comprise a combination of the plurality of hairpins from the second, fourth, and sixth hairpin layers. In the second embodiment, the first and second winding sets can each comprise six hairpins from the plurality of hairpins from each of the first, third, and fifth hairpin layers. The third and fourth winding sets can each comprise six hairpins from the plurality of hairpins from each of the second, fourth, and sixth hairpin layers. In a further embodiment, the first, second, third, fourth, fifth, and sixth hairpin layers can each comprise the same number of windings with a shortened pitch. For example, each of the first through sixth hairpin layers can contain at least four windings with a shortened pitch. An electric machine can incorporate the stator arrangement described above. The foregoing features and advantages and other features and advantages of the present invention will be readily apparent from the following detailed description of the best ways of carrying out the invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic fragmentary sectional view of an electric machine with a stator assembly having several winding sets; Fig. 2 is a schematic fragmentary sectional view of the stator assembly of Fig. 1; Fig. 3 is a schematic perspective view of hairpins that can be used in the stator assembly of Fig. 1; Fig. 4 is a schematic drawing of electrical connections between the winding sets in the stator assembly of Fig. 1 in accordance with a first embodiment; Fig. 5 is a schematic wiring diagram for the stator assembly of Fig. 4; and Fig. 6 is a schematic drawing of electrical connections between the winding sets in the stator assembly of Fig. 1 in accordance with a second embodiment. DETAILED DESCRIPTION With reference to the figures, where the same reference numerals in the multiple views denote identical or similar components, Fig. 1 is a schematic, fragmentary sectional view of an electric motor / generator or electric drive machine, here referred to as the electric machine 10. The electric machine 10 can be used in a vehicle 12. The vehicle 12 can be any passenger or commercial vehicle, such as a hybrid electric vehicle (including a plug-in hybrid electric vehicle), an extended-range electric vehicle, or other vehicles. The electric machine 10 can include any device configured to generate an electric machine torque, for example, by converting electrical energy into rotary motion.For example, the electric machine 10 can be configured to receive electrical energy from a power source, such as a battery array (not shown). The power source can be configured to store and output electrical energy. The vehicle 12 can include a rectifier / inverter (not shown) to convert the direct current (DC) voltage from the battery array into alternating current (AC) voltage. The electric machine 10 can be configured to use the AC voltage from the rectifier / inverter to generate rotary motion. The electric machine 10 can also be configured to generate electrical energy when supplied with mechanical energy, such as the mechanical energy (torque) of a power machine. With reference to Fig. 1, the electric machine 10 comprises a rotor assembly 14 and a stator assembly 16. The rotor assembly 14 is rotatable relative to and within the stator assembly 16 about a longitudinal axis 18 (extending outwards from the side in Fig. 1). The rotor assembly 14 can be annular in shape and positioned around a shaft (not shown). The rotor assembly 14 can be of any type known to those skilled in the art, including, but not limited to, a rotor with internal permanent magnets, a rotor with surface permanent magnets, an induction rotor, a synchronous rotor, a reluctance rotor, or a separately excited / wound field rotor. The specific configuration of the rotor assembly 14 is not shown in Fig. 1. With reference to Fig. 1, the stator assembly 16 comprises a plurality of stator slots 20 extending from a stator core 21. The stator slots 20 can extend lengthwise along the longitudinal axis 18 and can be evenly spaced radially apart from one another around the longitudinal axis 18. The stator assembly 16 can contain any number of slots or poles suitable for the application in question. In one example, the number of stator slots 20 is exactly 72 (Fig. 1 is intended only as a schematic representation) and the stator assembly 16 defines 8 poles. Fig. 2 is a schematic, fragmentary sectional view of the stator assembly 16. In the embodiment shown, the stator assembly 16 comprises 72 slots. Fig. 2 shows stator slot numbers S11 to S31. The plurality of stator slots 20 can define several slot layers, such as first, second, third, fourth, fifth, and sixth slot layers 22A, B, C, D, E, and F, as shown in Fig. 2. The first slot layer 22A is furthest from the outer diameter 23 of the stator core 21, and the sixth slot layer 22F is closest to the outer diameter 23 of the stator core 21. However, it should be noted that each stator slot 20 can contain a different number of layers, comprising, but not limited to, four or eight layers. With reference to Figs. 1-2, the stator slots 20 can be partially open or closed slots. With reference to Figs. 1-2, the stator assembly 16 includes a plurality of electrical conductors or hairpins 24. In a bar-winding design, the electrical conductor is typically referred to by those skilled in the art as a "hairpin" and is also referred to as such in this description. Fig. 3 is a schematic drawing of two types of electrical conductors or hairpins 24 that can be used in the stator assembly 16. It is understood that the hairpins 24 shown in Fig. 3 are only schematic and are not intended to represent the scale or specific shape of the hairpins 24 as known to those skilled in the art. With reference to Figs. 1-2, the hairpins 24 can have a substantially rectangular cross-section. However, any other cross-sectional shape can be used. With reference to Fig. 3, the hairpins 24 are segmented and comprise a first leg 26, a second leg 28, and a bent end section 30 between the first and second legs 26 and 28. The hairpins 24 are designed to allow current flow from the first leg 26 to the second leg 28. With reference to Fig. 3, the ends 32 of the hairpins 24, after being inserted into the stator slot 20, are bent outwards to allow welding connections between the hairpins 24. With reference to Fig. 3, two types of hairpins 24 are shown: a shortened-pitch winding 34 and a full-pitch winding 38. With reference to Fig. 3, the shortened-pitch winding 34 has a first span 40, and the full-pitch winding 38 has a second span 44. The span of the hairpin 24 can be defined as the angular distance between stator slots 20 through which a single hairpin 24 is positioned. As shown in Fig. 3, the second span 44 is larger than the first span 40. In other words, each hairpin 24 spans a predetermined number of stator slots 20. The shortened-pitch and full-pitch windings 34 and 38 are configured to extend over a first and second number, respectively, of the plurality of stator slots 20, the first number being smaller than the second.In one example, the first and second numbers are 8 and 9. With reference to Figs. 1-2, a stator slot lining 52 can be inserted into the stator slots 20 to electrically insulate the hairpins 24 from the stator core 21 and from each other. The hairpins 24 must be electrically insulated from the stator core to prevent phase-to-ground short circuits and from each other to prevent phase-to-phase short circuits. The hairpins 24 can be coated with lacquer, with the slot lining 52 providing additional protection. In the embodiment shown, the stator slots 20 are partially open slots, and the hairpins 24 and the stator slot lining 52 can be inserted axially or radially. However, the stator slots 20 can also be closed slots, and the hairpins 24 and the slot lining 52 can be inserted radially. Referring to Fig. 2, the hairpins 24 each have a first leg 26 inserted into one of the first, second, third, fourth, fifth, and sixth groove layers 22A-F, and a second leg 28 inserted into another of the first, second, third, fourth, fifth, and sixth groove layers 22A-F. The hairpins 24 can be divided into several hairpin layers, such as the first, second, third, fourth, fifth, and sixth hairpin layers 54A-F shown in Fig. 2 (and Figs. 4-5). The lines in Fig. 2 representing the hairpin layers 54A-F are only schematic and are not intended to show the scale or specific shape of the hairpins 24, as is known to those skilled in the art. With reference to Fig. 2, the first hairpin layer 54A (forward winding from first slot layer 22A to second slot layer 22B) is formed by the plurality of hairpins 24, the first leg 26A of which is located in the first slot layer 22A (e.g., in slot S21) and the second leg 28A of which is located in the second slot layer 22B (e.g., in slot S30). In other words, the first hairpin layer 54A is the forward winding from the first slot layer 22A to the second slot layer 22B. With reference to Fig. 2, the second hairpin layer 54B is defined by the plurality of hairpins 24, the first leg 26B of which is located in the second slot layer 22B (e.g., in slot S21) and the second leg 28B of which is located in the first slot layer 22A (e.g., in slot S12). In other words, the second hairpin layer 54B is the reverse winding from the second slot layer 22B to the first slot layer 22A. With reference to Fig. 2, the third hairpin layer 54C is defined by the plurality of hairpins 24, the first leg 26C of which is located in the third slot layer 22C (e.g., in slot S21) and the second leg 28C of which is located in the fourth slot layer 22D (e.g., in slot S30). In other words, the third hairpin layer 54C is the forward winding from the third slot layer 22C to the fourth slot layer 22D. With reference to Fig. 2, the fourth hairpin layer 54D is defined by the plurality of hairpins 24, the first leg 26D of which is located in the fourth slot layer 22B (e.g., in slot S21) and the second leg 28D of which is located in the third slot layer 22C (e.g., in slot S12). In other words, the fourth hairpin layer 54D is the reverse winding from the fourth slot layer 22D to the third slot layer 22C. With reference to Fig. 2, the fifth hairpin layer 54E is defined by the plurality of hairpins 24, the first leg 26E of which is located in the fifth slot layer 22E (e.g., in slot S21) and the second leg 28E of which is located in the sixth slot layer 22F (e.g., in slot S30). In other words, the fifth hairpin layer 54E is the forward winding from the fifth slot layer 22E to the sixth slot layer 22F. With reference to Fig. 2, the sixth hairpin layer 54F is defined by the plurality of hairpins 24, the first leg 26F of which is located in the sixth slot layer 22F (e.g., in slot S21) and the second leg 28E of which is located in the fifth slot layer 22E (e.g., in slot S12). In other words, the sixth hairpin layer 54F is the reverse winding from the sixth slot layer 22F to the fifth slot layer 22E. Fig. 4 is a schematic drawing of a first embodiment of the electrical connections 60 of the stator assembly 16. The hairpins 24 form several winding sets, such as first, second, third, and fourth winding sets 61, 62, 63, 64 (shown in Fig. 4) within the stator slots 20 (shown in Figs. 1-2). However, any number of winding sets can be configured according to the specific application. The first to fourth winding sets 61-64 can be connected in series or in parallel. The first to fourth winding sets 61-64 can define an identical number of multiple phases. In one embodiment, each winding set defines a "U" phase, a "V" phase, and a "W" phase. In another embodiment, each winding set defines five phases, i.e., the winding set defines a "U" phase, a "V" phase, an "X" phase, a "Y" phase, and a "Z" phase. However, the electrical machine 10 is not limited to a three-phase or five-phase machine and the number of phases may differ from those described here. As shown in Fig. 4, the first, second, third, and fourth winding sets 61-64 can be parallel to each other. Each of the first, second, third, and fourth winding sets 61-64 contains a different plurality of hairpins 24 connected in series. Fig. 5 is a schematic drawing of a winding layout 100 for the first to sixth hairpin layers 54A-F, corresponding to the connections shown in Fig. 4. Fig. 5 represents a stator arrangement 16 with 72 slots. The slot numbers are enclosed in brackets on the right-hand side by the letter “S” (so that numbers 1 to 72 correspond to slots S1 to S72). Fig. 5 shows all stator slots (S1-72), with the right-hand side of the figure folded over or adjoining the left-hand side. The letter “N” in Fig. 4 denotes the neutral connection, while U, V, and W denote the three phases. Although the winding layout 100 in Fig. 5 is shown for phase U, the layouts for phases V and W are similar. Other alternative configurations can be produced, for example, a “Y” configuration without a common neutral point or a delta connection, as is known to those skilled in the art. The first winding set 61 comprises a combination of hairpins 24 from the first and third hairpin layers 54A, C. Referring to Fig. 4-5, the first winding set 61 comprises a first winding set 66 from the first hairpin layer 54A and a second winding set 68 from the third hairpin layer 54C. The first and second winding sets 66, 68 are connected in series by a first bridge 84. Referring to Fig. 5, the first winding set 66 can contain 12 hairpins (see hairpins 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81 and 82) and the second winding set 68 can contain six hairpins (hairpins 85, 86, 87, 88, 89, 90). As shown in Fig. 5, the turn 82 of the first winding set 66 is connected to the turn 85 of the second winding set 68 via the first bridge 84. Figs. 4-5 show that the start cable 92 and the end cable 93 connect the ends of the first winding set 61. The second winding set 62 comprises a combination of hairpins 24 from the second and fourth hairpin layers 54B, D. Referring to Fig. 4-5, the second winding set 62 includes a third winding set 94 from the second hairpin layer 54B and a fourth winding set 96 from the fourth hairpin layer 54D. The third and fourth winding sets 94, 96 are connected in series by a second bridge 98. Fig. 4 shows that the start cable 101 and the end cable 99 connect the ends of the second winding set 62. The third winding set 63 comprises a combination of hairpins 24 from the fifth and third hairpin layers 54E, C. Referring to Figs. 4-5, the third winding set 63 comprises a fifth winding set 102 from the fifth hairpin layer 54E and a sixth winding set 104 from the third hairpin layer 54C. The fifth and sixth winding sets 102, 104 are connected in series by a third bridge 106. The fourth winding set 64 comprises a combination of hairpins 24 from the sixth and fourth hairpin layers 54F, D. Referring to Figs. 4-5, the fourth winding set 64 comprises a seventh winding set 108 from the sixth hairpin layer 54F and an eighth winding set 110 from the fourth hairpin layer 54D. The seventh and eighth winding sets 108, 110 are connected in series by a fourth bridge 112. Referring to Figs. 4-5, the first, third, fifth, and seventh winding sets 66, 94, 102, 108 each contain twelve hairpins, and the second, fourth, sixth, and eighth winding sets 68, 96, 104, 110 each contain six hairpins. Referring to Fig. 5, the third hairpin layer 54 is shared by the first and third winding sets 61, 63. The fourth hairpin layer 54D is shared by the second and fourth winding sets 62, 64. The shared use of hairpins 24 from the third and fourth hairpin layers 54C-D can compensate for an asymmetry between the rotor pole and stator tooth tips (not shown). The winding layout 100 is designed such that no voltage potential exists between parallel connections. The first, second, third, fourth, fifth, and sixth hairpin layers 54A-F (shown in Fig. 2) each contain a combination of shortened-pitch and full-pitch windings 34, 38 (shown in Fig. 3). As mentioned above, the shortened-pitch and full-pitch windings 34, 38 are configured to extend over a first and second number, respectively, of the plurality of stator slots 20, the first number being smaller than the second number. In the first embodiment, the third and fourth hairpin layers 54C, 54D can comprise more windings 34 with a reduced pitch than each of the first, second, fifth, and sixth hairpin layers 54A, B, E, F. Referring to Fig. 5, the first, second, fifth, and sixth hairpin layers 54A, B, E, F can each comprise at least two hairpins with a reduced pitch, for example, first and second hairpins 114, 116 with a reduced pitch. In the embodiment shown, the first and second hairpins 114, 116 with a reduced pitch each span eight slots, from slot S11 to S19 and from slot S12 to S20, respectively. Referring to Fig. 5, the third and fourth hairpin layers 54C and 54D can each contain at least four hairpins with a reduced step size, such as third, fourth, fifth and sixth hairpins 118, 120, 122, 124 with a reduced step size.In the embodiment shown, the third to sixth hairpins 118, 120, 122, 124 each span eight grooves with a shortened step width, from groove S11 - S19, from S12 - S20 and from S47 - S55, from S48 - S56 (layer 54C) or from S56 - S64, from S57 - S65 and from S20 - S28, from S21 - S29 (layer 54D). Fig. 6 is a schematic drawing of a second embodiment of the electrical connections 160, which can be used in the stator arrangement 16 of Fig. 1. As shown in Fig. 6, the first, second, third, and fourth winding sets 161, 162, 163, and 164 are parallel to each other. Each of the first, second, third, and fourth winding sets 161–164 contains a different plurality of hairpins 24 connected in series. In the second embodiment, the first and second winding sets 161, 162 can both comprise a combination of hairpins 24 from any of the six hairpin layers 54A - F, e.g. they can comprise a combination of hairpins 24 from the first, third and fifth hairpin layers 54A, C, E or a combination of other hairpin layers. With reference to Fig. 6, the first winding set 161 comprises first, second, and third winding sets 166, 168, 170 (connected in series by respective bridges 192) from the first, third, and fifth hairpin layers 54A, C, E, respectively. With reference to Fig. 6, the second winding set 162 comprises fourth, fifth, and sixth winding sets 174, 176, 178 (connected in series by respective bridges 192) from the first, third, and fifth hairpin layers 54A, C, E, respectively. Each of the first to sixth winding sets 166, 168, 170, 174, 176, 178 can contain six hairpins 24.In other words, the first and second winding sets 161, 162 can each contain six hairpins 24 from each of the first, third and fifth hairpin layers 54A, C, E. The third and fourth winding sets 163, 164 can both comprise a combination of hairpins 24 from any of the six hairpin layers 54A - F, for example, they can contain a combination of hairpins 24 from the second, fourth and sixth hairpin layers 54B, D, F. With reference to Fig. 6, the third winding set 163 comprises the seventh, eighth, and ninth winding sets 180, 182, 184 (connected in series by respective bridges 192) from the second, fourth, and sixth hairpin layers 54B, D, F, respectively. With reference to Fig. 6, the fourth winding set 164 comprises the tenth, eleventh, and twelfth winding sets 186, 188, 190 (connected in series by respective bridges 192) from the second, fourth, and sixth hairpin layers 54B, D, F, respectively. Each of the sixth to twelfth winding sets 180, 182, 184, 186, 188, 190 can contain six hairpins 24.In other words, the third and fourth winding sets 163, 164 can each contain six hairpins 24 from each of the second, fourth and sixth hairpin layers 54B, D, F. Therefore, in the second embodiment, the first, third, and fifth hairpin layers 54A, C, E of the first and second winding sets 161, 162 can be shared, while the second, fourth, and sixth hairpin layers 54B, D, F of the third and fourth winding sets 163, 164 can be shared. The windings in Fig. 6 are connected in a delta configuration, but they can alternatively be connected in a Y configuration, as in Fig. 4. The configurations outlined above allow for greater flexibility in the design of an electric machine 10 with a specific torque or system voltage requirement. Arbitrarily specifying a configuration for an electric machine 10 will not produce the required torque output or meet minimum noise requirements. Only specific configurations with a specific number of slots, a specific number of phases, a specific number of poles, a specific number of winding sets, a specific configuration of hairpin layers 54A-F (relative to slot layers 22A-F), etc., will produce the desired functionality. These specific configurations cannot be determined simply through investigation. If an arrangement is not chosen correctly, the design will either perform poorly or fail to meet the functional requirements.Due to the large number of possible combinations, functioning configurations are neither easy to determine nor obvious. The detailed description and the drawings or figures support and describe the invention, but the scope of the invention is defined only by the claims. Although some of the best ways and other embodiments for carrying out the claimed invention have been described in detail, various alternative designs and embodiments exist for putting the invention, as defined in the accompanying claims, into practice.

Claims

Stator arrangement (16) comprising: a plurality of stator slots (20) defining multiple slot layers (22A, ..., 22F); a plurality of hairpins (24), each having a first leg (26) positioned in one of the multiple slot layers (22A, ..., 22F) and a second leg (28) positioned in another of the multiple slot layers (22A, ..., 22F), each of the plurality of hairpins (24) being configured to allow current flow from the respective first leg (26) to the respective second leg (28); wherein the plurality of hairpins (24) is subdivided into multiple hairpin layers (54A, ..., 54F); wherein the plurality of hairpins (24) forms multiple winding sets (61, 62, 63, 64), each of the multiple winding sets (61, 62, 63, 64) at least partially contains the plurality of hairpins (24) from at least two of the multiple hairpin layers (54A, ..., 54F);wherein: the multiple hairpin layers (54A, ..., 54F) comprise first, second, third, fourth, fifth and sixth hairpin layers (54A, ..., 54F); the multiple winding sets (61, 62, 63, 64) comprise first, second, third and fourth winding sets (61, 62, 63, 64); and the multiple groove layers (22A, ..., 22F) comprise first, second, third, fourth, fifth and sixth groove layers (22A, ..., 22F); wherein: the first hairpin layer (54A) is defined by the plurality of hairpins (24) whose respective first leg (26A) is located in the first groove layer (22A) and whose respective second leg (28A) is located in the second groove layer (22B); the second hairpin layer (54B) is defined by the plurality of hairpins (24) whose respective first leg (26B) is located in the second groove layer (22B) and whose respective second leg (28B) is located in the first groove layer (22A);the third hairpin layer (54C) is defined by the plurality of hairpins (24) whose respective first leg (26C) is located in the third groove layer (22C) and whose respective second leg (28C) is located in the fourth groove layer (22D); the fourth hairpin layer (54D) is defined by the plurality of hairpins (24) whose respective first leg (26D) is located in the fourth groove layer (22D) and whose respective second leg (28D) is located in the third groove layer (22C); the fifth hairpin layer (54E) is defined by the plurality of hairpins (24) whose respective first leg (26E) is located in the fifth groove layer (22E) and whose respective second leg (28E) is located in the sixth groove layer (22F);the sixth hairpin layer (54F) is defined by the plurality of hairpins (24) whose respective first leg (26F) is located in the sixth groove layer (22F) and whose respective second leg (28F) is located in the fifth groove layer (22E); wherein: the first winding set (61) comprises a combination of the plurality of hairpins (24) from the first (54A) and third hairpin layers (54C); the second winding set (62) comprises a combination of the plurality of hairpins (24) from the second (54B) and fourth hairpin layers (54D); the third winding set (63) comprises a combination of the plurality of hairpins (24) from the fifth (54E) and third hairpin layers (54C); and the fourth winding set (64) comprises a combination of the multitude of hairpins (24) from the sixth (54F) and fourth hairpin layers (54D);wherein: the first winding set (61) comprises 12 from the plurality of hairpins (24) from the first hairpin layer (54A) connected in series with 6 from the plurality of hairpins (24) from the third hairpin layer (54C); the second winding set (62) comprises 12 from the plurality of hairpins (24) from the second hairpin layer (54B) connected in series with 6 from the plurality of hairpins (24) from the fourth hairpin layer (54D); the third winding set (63) comprises 12 from the plurality of hairpins (24) from the fifth hairpin layer (54E) connected in series with 6 from the plurality of hairpins (24) from the third hairpin layer (54C); and the fourth winding set (64) comprises 12 from the plurality of hairpins (24) from the sixth hairpin layer (54F) connected in series with 6 from the plurality of hairpins (24) from the fourth hairpin layer (54D). Stator arrangement (16) according to claim 1: wherein each of the plurality of hairpins (24) is a shortened-pitch winding (34) or a full-pitch winding (38), wherein the shortened-pitch and full-pitch windings (34, 38) are configured to extend over a first and second number of the plurality of stator slots (20), respectively, such that the first number is smaller than the second number; wherein the first, second, third, fourth, fifth and sixth hairpin layers (54A, ..., 54F) each contain both shortened-pitch windings (34) and full-pitch windings (38); and wherein the third hairpin layer (54C) contains more shortened-pitch windings (34) than each of the first, second, fifth and sixth hairpin layers (54A, ..., 54F). Stator arrangement (16) according to claim 2, wherein: the third and fourth layers each contain at least four windings (34) with a reduced step size; and the first (54A), second (54B), fifth (54E) and sixth hairpin layer (54F) each contain at least two windings (34) with a reduced step size. Stator arrangement (16) according to claim 1, wherein: the first winding set (61) and the second winding set (62) each comprise a combination of the plurality of hairpins (24) from the first (54A), third (54C) and fifth hairpin layer (54E); and the third winding set (63) and the fourth winding set (64) each comprise a combination of the plurality of hairpins (24) from the second (54B), fourth (54D) and sixth hairpin layer (54F). Stator arrangement (16) according to claim 4, wherein: the first (61) and second winding set (62) each contain 6 from the plurality of hairpins (24) from each of the first (54A), third (54C) and fifth hairpin layers (54E); and the third (63) and fourth winding set (64) each contain 6 from the plurality of hairpins (24) from each of the second (54B), fourth (54D) and sixth hairpin layers (54F). An electrical machine comprising: a stator assembly (16); a rotor assembly (14) rotatable relative to the stator assembly (16); wherein the stator assembly (16) comprises: a plurality of stator slots (20) defining the first, second, third, fourth, fifth, and sixth slot layers (22A, ..., 22F); a plurality of hairpins (24), each having a respective first leg (26) positioned in one of the first, second, third, fourth, fifth, and sixth slot layers (22A, ..., 22F), and a respective second leg (28) positioned in another of the first, second, third, fourth, fifth, and sixth slot layers (22A, ..., 22F), each of the plurality of hairpins (24) being configured to allow current flow from the respective first leg (26) to the respective second leg (28);wherein the multitude of hairpins (24) is subdivided into first, second, third, fourth, fifth and sixth hairpin layers (54A, ..., 54F); and the plurality of hairpins (24) forms first, second, third and fourth winding sets (61, 62, 63, 64), each of the first, second, third and fourth winding sets (61, 62, 63, 64) containing at least part of the plurality of hairpins (24) from at least two of the first, second, third, fourth, fifth and sixth hairpin layers (54A, ..., 54F); wherein: the multiple hairpin layers (54A, ..., 54F) comprise first, second, third, fourth, fifth and sixth hairpin layers (54A, ..., 54F); the multiple winding sets (61, 62, 63, 64) comprise first, second, third and fourth winding sets (61, 62, 63, 64); and the multiple groove layers (22A, ..., 22F) comprise first, second, third, fourth, fifth and sixth groove layers (22A, ..., 22F);wherein: the first hairpin layer (54A) is defined by the plurality of hairpins (24) whose respective first leg (26A) is located in the first groove layer (22A) and whose respective second leg (28A) is located in the second groove layer (22B); the second hairpin layer (54B) is defined by the plurality of hairpins (24) whose respective first leg (26B) is located in the second groove layer (22B) and whose respective second leg (28B) is located in the first groove layer (22A); the third hairpin layer (54C) is defined by the plurality of hairpins (24) whose respective first leg (26C) is located in the third groove layer (22C) and whose respective second leg (28C) is located in the fourth groove layer (22D);the fourth hairpin layer (54D) is defined by the plurality of hairpins (24) whose respective first leg (26D) is located in the fourth slot layer (22D) and whose respective second leg (28D) is located in the third slot layer (22C); the fifth hairpin layer (54E) is defined by the plurality of hairpins (24) whose respective first leg (26E) is located in the fifth slot layer (22E) and whose respective second leg (28E) is located in the sixth slot layer (22F); the sixth hairpin layer (54F) is defined by the plurality of hairpins (24) whose respective first leg (26F) is located in the sixth slot layer (22F) and whose respective second leg (28F) is located in the fifth slot layer (22E); wherein: the first winding set (61) a The combination comprises the multitude of hairpins (24) from the first (54A) and third hairpin layer (54C);the second winding set (62) comprises a combination of the plurality of hairpins (24) from the second (54B) and fourth hairpin layer (54D); the third winding set (63) comprises a combination of the plurality of hairpins (24) from the fifth (54E) and third hairpin layer (54C); and the fourth winding set (64) comprises a combination of the plurality of hairpins (24) from the sixth (54F) and fourth hairpin layers (54D); wherein: the first winding set (61) comprises 12 from the plurality of hairpins (24) from the first hairpin layer (54A) connected in series with 6 from the plurality of hairpins (24) from the third hairpin layer (54C); the second winding set (62) comprises 12 from the plurality of hairpins (24) from the second hairpin layer (54B) connected in series with 6 from the plurality of hairpins (24) from the fourth hairpin layer (54D);the third winding set (63) comprises 12 from the plurality of hairpins (24) from the fifth hairpin layer (54E) connected in series with 6 from the plurality of hairpins (24) from the third hairpin layer (54C); and the fourth winding set (64) comprises 12 from the plurality of hairpins (24) from the sixth hairpin layer (54F) connected in series with 6 from the plurality of hairpins (24) from the fourth hairpin layer (54D).

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