Patent Application
20240039378
The present disclosure relates to the field of electric machines, and more particularly, stator winding arrangements and connections for such winding arrangements.
Electric machines are designed to meet specific operating requirements that depend at least in part on the intended application for the electric machine. Examples of design features that contribute to operating performance include stator size, rotor size, type and arrangement of the windings, and any of various other design parameters as will be recognized by those of ordinary skill in the art. All operating requirements for the electric machine must be met while also meeting certain space constraints that are also dependent upon the intended application for the electric machine.
In some applications, designers will strive to reduce the number of electrical conductor terminations and connections in the stator assembly, as a need to physically connect conductors in the stator core assembly adversely impacts cost and complexity of the manufacturing process. To this end, some stator windings utilize continuous conductor paths, including those having a square or rectangular cross-section for use in high-slot-fill, multi-phase stator winding configurations. Each such continuous conductor path includes a series of straight conductor segments disposed in respective slots of the stator core, which straight conductor segments are interconnected by end loop segments that project axially from either end of the core. In at least some winding arrangements, the end loop segments are readily formed of first and second legs that extend first radially-outwardly and then radially-inwardly, respectively, to thereby permit successive straight segments to reside in a common layer of different slots of the stator core, thereby providing a “cascaded” winding configuration.
Cascaded windings typically feature some radial transition of each conductor path between layers. However, because these transitions present significant manufacturing challenges and costs, these transitions are typically limited. Different connection challenges are encountered by designers depending on the winding features and the type of winding. For example, for a specific winding arrangement, it is often challenging to make special connections between certain winding segments between different layers, different paths, and/or those associated with different coils. When making such connections, care must be taken to maintain the desired operating requirements, including good balance between winding phases, while also maintaining the winding within the desired size constraints.
In view of the forgoing, it would be desirable to provide an electric machine with a cascaded winding arrangement having a high slot-fill-ratio and excellent phase balance, while also maintaining the desired size constraints. It would also be desirable to make such connections without compromising other operating requirements. Furthermore, it would be advantageous for such winding arrangement to be configured such that it is relatively easy and economical to manufacture a stator that includes the winding arrangement.
While it would be desirable to provide an electric machine that provides one or more of these or other advantageous features as may be apparent to those reviewing this disclosure, the teachings disclosed herein extend to those embodiments which fall within the scope of any eventually appended claims, regardless of whether they accomplish one or more of the above-mentioned advantages.
A stator for an electric machine includes a stator core having a plurality of slots formed therein and a multi-phase winding arrangement positioned on the stator core. The winding arrangement includes a plurality of cascaded conductors arranged in layers of the slots, the layers defining multiple layer pairs. The plurality of cascaded conductors form a plurality of parallel paths per phase, each of the parallel paths making multiple revolutions of the core with each revolution occurring within a layer pair. For each layer pair, a number of weaves (N) are formed between a first parallel path and a second parallel path in said layer pair, wherein N is greater than or equal to two.
In at least one embodiment, the winding arrangement of the stator defines a plurality of poles and includes a plurality of cascaded conductors arranged in layers of the slots. The layers of the slots define a plurality of layer pairs including at least a first layer pair and a second layer pair. The cascaded conductors form a plurality of parallel paths per phase in each of the layer pairs. A first plurality of weaves are formed between the parallel paths in the first layer pair, wherein said first plurality of weaves are associated with multiple poles of the plurality of poles including a first pole and a second pole. A second plurality of weaves are formed between said plurality of parallel paths in the second layer pair, wherein said second plurality of weaves also associated with the first pole and the second pole.
In at least one embodiment, the multi-phase winding arrangement includes a plurality of cascaded conductors arranged in layers of the slots, the layers defining multiple layer pairs. The plurality of cascaded conductors form a plurality of parallel paths per phase, each of the parallel paths making multiple revolutions of the core with each revolution occurring within a layer pair. For each layer pair, a first weave and a second weave are formed between a first parallel path and a second parallel path in said layer pair. The first weave is associated with a first pole of the plurality of poles, and the second weave is associated with a second pole of the plurality of poles. The first pole and the second pole are 1800 opposite one another on the stator core.
A stator for an electric machine is disclosed herein and includes a stator core with a winding arrangement positioned thereon. In at least one embodiment, the winding arrangement includes four cascaded parallel paths per phase, wherein each parallel path is associated with an adjacent cascaded parallel path and a complementary cascaded parallel path. The winding arrangement includes multiple weaves of complementary parallel paths within each layer pair. In at least one embodiment, four weaves of cascaded parallel paths are formed within each layer pair, per phase. For each weave of a layer pair, one cascaded parallel path switches layers with its complementary parallel path.
Stator Core
Referring now to
Winding Conductors
Referring now to
The end loop 42 includes a first sloped portion 50 and a second sloped portion 52 that meet at an apex portion 54. The first sloped portion 50 is substantially co-radial with the common layer 48, the first straight segment 44 and the second straight segment 46. The second sloped portion 52 is substantially non-co-radial with the common layer 48, the first straight segment 44 and the second straight segment 46. The apex portion 54 includes a first radial extension portion 56. The first radial extension portion 56 extends from the first sloped portion 50 in the radially outward direction, which provides a radial outward adjustment for the end loop 42. A second sloping radial extension portion 58 connects the second sloped portion 52 and the second straight 46. The second radial extension portion 58 extends from the second sloped portion 52 in the radially inward direction, which provides a radial inward adjustment for the end loop 42.
While the end loop 42 has been shown wherein the radial outward adjustment is adjacent the apex portion 54 and the radial inward adjustment is adjacent the second sloped portion 52, it will be recognized that this is but one embodiment of an end loop segment that may be used in association with the cascaded winding arrangement described in further detail below. Those skilled in the art can appreciate that the radial outward and inward adjustments can be on any one or on any two of the first sloped portion 50, the second sloped portion 52, and the apex portion 54 in order to provide the cascaded winding pattern. Moreover, it will be recognized that other arrangements of the end loop 42 are possible in order to provide the cascaded winding pattern disclosed herein.
Referring now to
The straight segment 46 extends through a one of the core slots 12 from the first end 18 to the second end 20 of the stator core 10. As the first straight segment 46 exits the second end 20, the first straight segment 46 is attached to an end of another end loop, shown schematically at 66, which is substantially identical to the end loops 42, 60, and 62. The end loop 66 is attached at another end to a second straight segment, shown schematically at 44. The second straight segment 44 extends upwardly through another one of the core slots 12 of the stator core 10 and attaches to a portion 44a of another end loop 42a, which is substantially identical to the end loop segments 42, 60, and 62. Similarly, the end loop segment 42a connects to another straight segment 46a and returns to the opposite end of the stator core 10. The pattern of connecting end loop segments 42, 66, and 42a and straight segments, such as the straight segments 44, 46, 44a, 46a, as outlined above, continues throughout one substantial pass (i.e., a revolution) about the circumference of the stator core 10. Thereafter, each conductor path may transition to additional layers and make one or more additional passes around the stator core, as explained in further detail below.
As will be recognized from
Winding Arrangement
With reference now to
With particular reference now to
As noted above, the conductors of the winding 70 are arranged in eight (8) layers within the slots. Each phase of the winding 70 includes four parallel paths and each parallel path makes four revolutions around the stator core. The leads to each of the paths are illustrated in
The winding 70 of
The winding 70 of
After extending through the core at layer seven of slot 42, a weave end turn 76 causes path 1 to return back to layer eight at slot 48. Together weave end turn 76 and weave end turn 77 form a weave of two conductor paths that results in complementary cascaded parallel paths 1 and 7 switching layer positions (i.e., weave end turn 76 results in path 1 moving to layer eight and weave end turn 77 results in path 7 moving to layer seven, wherein paths 1 and 7 are complementary cascaded parallel paths). Accordingly, the term “weave” as used herein refers to an end loop configuration that results in one cascaded parallel path switching layers with a complementary cascaded parallel path within a given layer pair. A weave is considered to be “associated with a pole” when the weave occurs in association with an end loop extending between said pole and an adjacent pole of the phase.
With continued reference to
With continued reference to
Following end turn 86, path 1 extends through the core at layer seven of slot 121. Thereafter, a series of cascaded end loops 88 cause path 1 to move successively through layer seven in each of slots 127, 133, 139 and 1 (see
With path 1 now in middle outer layer pair (i.e., layers five and six), the path completes another revolution of the stator core, similar to that described in the preceding paragraphs. The complete trace of path 1 is not described in detail herein for the sake of brevity, however, it will be recognized that the trace through the middle-outer layer pair is substantially similar to the trace through outermost layer pair. Accordingly the trace of path 1 through the middle-outer layer pair includes numerous cascaded end turns that allow path 1 to remain in the same layer in successive slots (similar to end turns 74, 78, 84 and 88), two end turns that are associated with weaves allowing complementary cascaded parallel paths 1 and 7 to switch layer within the layer pair (similar to end turns 76 and 86), and one over-under end turn arrangement (similar to over-under arrangement 80) that causes adjacent cascaded parallel paths 1 and 2 to switch left and right positions.
After completing another revolution of the stator core in the middle-outer layer pair (i.e., layers five and six), path 1 is then moved to the middle-inner layer pair (i.e., layers three and four). This is accomplished by one of the long pitch end turns 94 shown in
Following the long pitch end turns 94, path 1 continues with another revolution of the core in the middle-inner layer pair. Again, this revolution around the core is similar to that described previously in association with the outermost layer pair. Accordingly the trace of path 1 through the middle-inner layer pair includes numerous cascaded end turns that allow path 1 to remain in the same layer in successive slots (similar to end turns 74, 78, 84 and 88), two end turns that are associated with weaves allowing complementary cascaded parallel paths 1 and 7 to switch layer with the layer pair (similar to end turns 76 and 86), and one over-under end turn arrangement (similar to over-under arrangement 80) that causes adjacent cascaded parallel paths 1 and 2 to switch left and right positions.
After completing the revolution of the core in the middle-inner layer pair, path 1 then transitions to the inner most layer pair (i.e., layers 1 and 2). Again, this revolution around the core is similar to those described previously. Finally, path 1 terminates at layer one of slot 1, where another lead is provided to the path (as indicated by the bold box around path 1). This completes the trace for path 1, which includes four revolutions around the stator core and two weaves per revolution. Paths 2, 7 and 8 are parallel paths of the same phase as path 1. The traces of these paths are similar to that of path 1. While these traces have not been described in detail herein for the sake of brevity, the exact traces of these paths is evident from the tabular schematic diagram of
In view of the foregoing, it will be recognized that the winding arrangement disclosed herein includes a cascaded winding arrangement including multiple weaves for each cascaded parallel path in each layer pair. Each weave is comprised of two end turns, including a first weave end turn (e.g., 76 or 86) and a second weave end turn (e.g., 77 or 87). The weaves of each phase, and of each parallel path of such phase (e.g., each of paths 1, 2, 7 and 8 in
In addition to the above, it will be recognized that the winding arrangement 70 disclosed herein includes two sets of adjacent cascaded parallel paths per phase (e.g., paths 1 and 2 are a first set of adjacent cascaded parallel paths, and paths 7 and 8 are a second set of adjacent cascaded parallel paths). Moreover, each parallel path of each phase also has a complementary cascaded parallel path (e.g., path 7 is a complementary cascaded parallel path to path 1, and path 8 is a complementary cascaded parallel path to path 2). This arrangement results in each layer pair having four weaves. For example, at layer pair seven-eight, two weaves are associated with the pole of slots 42-44 (i.e., a first weave between path 1 and path 7 and a second weave between path 2 and path 8), and two weaves are associated with the pole of slots 114-116 (i.e., a first weave between path 1 and path 7 and a second weave between path 2 and path 8). When all of the layer pairs are considered, there are sixteen total weaves in the winding arrangement, including four weaves associated with each layer pair.
The foregoing winding arrangement results in a winding with exceptional layer balancing of the individual parallel wires. For each phase, each parallel wire is housed in the same average layer position as the other parallel wires, for all the slots of a slot type of all the poles. The winding includes more than N weaves for each parallel path per phase, wherein N is an even number greater than or equal to two. The weaves of each layer pair are also spaced equally apart. Moreover, the weaves for each layer pair are associated with the same poles.
Although the various embodiments have been provided herein, it will be appreciated by those of skill in the art that other implementations and adaptations are possible. For example, although the cascaded winding arrangement has been described herein as being formed from continuous conductors, it would also be possible to form the winding from segmented portions of wire. As another example, while the exemplary winding arrangement disclosed herein only includes two weaves for each pair of complementary cascaded parallel paths, additional weaves are also possible, such as three, four, or more. Additionally, it will be recognized that certain terms such as up, down, left, right, etc. are terms of convenience based on a particular orientation and viewpoint of the stator and that opposite or different terms may be used to describe the same embodiment of the stator, depending on perspective. Furthermore, aspects of the various embodiments described herein may be combined or substituted with aspects from other features to arrive at different embodiments from those described herein. Thus, it will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by any eventually appended claims.
