CN114830497A - Stator assembly for an electric motor - Google Patents

Abstract

A stator assembly (10) for an electric motor (100) has a stator body (12), a plurality of slots (14) formed in the stator body (12), and a plurality of hairpins electrically connected together Phase winding of winding (24). The phase winding has a first phase winding branch (50) and a second phase winding branch (52). The plurality of slots (14) form at least one slot pair (19) surrounding the stator body (12). Each slot (14) of the slot pair (19) includes N radial slot positions (16, 18, 20, 22). N is an even number. Each radial slot location (16, 18, 20, 22) has an arm of a hairpin winding (24) located therein. The first phase winding branch (50) and the second phase winding branch (52) each comprise an equal number of hairpins distributed between the first slot (15) and the second slot (17) of the slot pair (19) arm. Each hairpin arm of the first phase winding branch (50) in the first slot (15) is in a corresponding position with the hairpin arm of the second phase winding branch (52) in the second slot (17) radial position. The first phase winding branch (50) and the second phase winding branch (52) are electrically connected in parallel.

Description

Stator assemblies for electric motors

technical field

The present invention relates to a stator assembly for an electric motor, an electric motor including such a stator assembly, and an electric vehicle including such an electric motor.

Background technique

Electric motors with stator assemblies utilizing hairpin windings are known to provide benefits including increased slot fill factor. However, conventional electric motors using hairpin windings have been found to suffer from a number of problems including, but not limited to, large back EMF values in use, increased AC losses, and imbalance in back EMF, resistive and inductive paths, all due to circulating currents Copper losses increase.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a stator assembly for an electric motor, the stator assembly comprising a stator body, a plurality of slots formed in the stator body, and a plurality of hairpin windings electrically connected together The phase winding includes a first phase winding branch and a second phase winding branch, wherein a plurality of slots form at least one slot pair around the stator body, each slot of the slot pair including N radial slot positions , N is an even number, and each radial slot location has an arm of the hairpin winding located therein, wherein the first and second phase winding branches each include first and second slots distributed in a pair of slots An equal number of hairpin arms between the slots, each hairpin arm of the first phase winding leg in the first slot in a corresponding position with the hairpin arm of the second phase winding leg in the second slot radial position, and the first phase winding branch and the second phase winding branch are electrically connected in parallel.

The stator assembly according to the first aspect of the invention may be primarily beneficial because the first and second phase winding branches each comprise an equal number of hairpin arms distributed between the first and second slots of the pair of slots, the first Each hairpin arm of a first phase winding leg in a slot is in a radial position corresponding to the hairpin arm of a second phase winding leg in a second slot, and the first and second phase winding legs The circuits are electrically connected in parallel.

In particular, by dividing the phase winding into first and second phase winding branches electrically connected in parallel, the level of the induced voltage in the phase winding is reduced due to back EMF and armature reactance to make operation compatible with the available supply voltage . However, in the case where an unequal number of hairpin arms is arranged in the pair of slots of each parallel branch, for example if the first parallel branch comprises more or less in the pair of slots than the second parallel branch In the case of hairpin arms, there may be phase and/or amplitude differences in the induced operating voltages between the first and second parallel branches.

By including an equal number of hairpin arms for each parallel branch within the pair of slots, the phase and/or amplitude difference of the back EMF and armature reaction produced by the currents flowing in the parallel paths in the first and second slots can be reduced or eliminated.

However, the first phase winding branch includes the arms of the hairpin windings located only in the first subset of radial slot locations and the second phase winding branch includes hairpin windings located only in the second subset of radial slot locations In the arrangement of the arms of the clamp winding, there may be uneven current flow through the first and second phase winding branches. In particular, radial slot locations located closer to the motor rotor in use may have additional induced voltages caused by additional leakage flux. This can lead to unbalanced resistances and inductances, for example where the first phase winding branch only includes arms at certain eg inner radial slot positions and the second phase winding leg only includes arms at some other eg outer radial slot positions arm arrangement. This can cause additional circulating currents or AC losses due to the current imbalance in each path.

By having an arrangement in which each hairpin arm of the first phase winding leg in the first slot is in a radial position corresponding to the hairpin arm of the second phase winding leg in the second slot (ie, by In the first and second phase winding branches comprising an equal number of hairpin arms distributed between corresponding radial slot positions of the first and second slots), the first and second phase winding branches may have more Balanced resistance and inductance, and thus can reduce circulating current and AC losses.

For a given input current, reducing circulating currents and AC losses in the windings can improve motor efficiency and/or thermal performance.

The first and second slots of the pair of slots may be circumferentially spaced from each other around the stator body, eg with at least one further slot between the first and second slots. The first and second slots may be spaced at a slot pitch around the stator body.

The phase windings may be located in a plurality of slots provided around the stator body. For example, the phase windings may be located in a first slot of adjacent slots and a second slot of adjacent slots, with a plurality of intermediate slots between the first and second slots. Each channel may include a plurality of adjacent grooves. The stator assembly may include multiple slot pairs. Each channel may include at least one slot of a pair of slots as previously described. For example, the first channel may comprise a plurality of first grooves of a plurality of groove pairs, and the second channel may comprise a plurality of second grooves of a plurality of groove pairs.

Each channel may include an equal number of hairpin arms distributed between the first and second phase winding legs. For example, each slot may include N hairpin arms in the first phase winding branch and N hairpin arms in the second phase winding branch.

Each channel may include an equal number of hairpin arms distributed between corresponding radial slot positions of the slots within the channel. For example, each slot may include N hairpin arms of the first phase winding branch distributed over each of N radial slot locations, and each slot may include N radial slots distributed N hairpin arms of the second phase winding branch on each of the positions. This provides uniform current distribution within each slot in use.

The hairpin arms of the first phase winding branch may be arranged in a first subset of radial slot locations within the first slot, and the hairpin arms of the second phase winding branch may be arranged radially in the second slot. Towards the second subset of slot locations, the radial slot locations of the first subset correspond to the radial slot locations of the second subset. For example, where the winding hairpin arm of the first phase winding leg is located at the first radial slot position of the first slot, the winding hairpin arm of the second phase winding leg may be located at the first radial slot position of the second slot Radial slot location.

The hairpin arms of the first phase winding leg may be disposed in the first slot in a first pattern, the hairpin arms of the first phase winding leg may be disposed in the second slot in a second pattern, and the second pattern Can be reversed from the first pattern.

The plurality of hairpin windings can include a first set of hairpin windings having a first cross-sectional area and a second set of hairpin windings having a second cross-sectional area, wherein the first cross-sectional area is greater than the second cross-sectional area . The first set of hairpin windings may be located radially outward of the second set of hairpin windings. This can be beneficial because positioning the smaller cross-sectional area arms at the radially inner slot locations can reduce AC losses induced in those hairpin arms that are more concentrated at the radially inner slot locations caused by the leakage flux of the slot. A hairpin arm connection with a smaller cross-sectional area has a smaller proportion of magnetic flux and less induced AC losses. The consequent splitting of these smaller cross-sectional area arms can be used to reduce or eliminate the possibility of circulating currents and losses within the phase path.

The first slot of the slot pair may include N/2 hairpin arms of the first phase winding leg and N/2 hairpin arms of the second phase winding leg. The second slot of the slot pair may include N/2 hairpin arms of the first phase winding leg and N/2 hairpin arms of the second phase winding leg.

Hairpin arms located at odd radial slot positions of the first slot may be electrically connected in series with hairpin arms located at even radial slot positions of the second slot of the pair to form a first phase winding leg and located at Hairpin arms at even radial slot locations of the first slot may be electrically connected in series with hairpin arms at odd radial slot locations of the second slot to form a second phase winding leg.

According to a second aspect of the invention there is provided an electric motor comprising a stator according to the first aspect of the invention.

According to a third aspect of the present invention, there is provided an electric vehicle comprising an electric motor according to the second aspect of the present invention.

According to a fourth aspect of the present invention, there is provided a stator assembly for an electric motor, the stator assembly comprising a stator body, a plurality of slots formed in the stator body, and a plurality of hairpin windings electrically connected together The phase winding includes a first phase winding branch and a second phase winding branch, wherein a plurality of slots form at least one slot pair around the stator body, each slot of the slot pair including N radial slot positions , N is an even number, and where the arms of the hairpin windings located in odd radial slot positions of the first slot of the slot pair and the arms of the hairpin windings located in the even radial slot positions of the second slot of the slot pair Electrically connected in series to form a first phase winding leg, the arms of the hairpin winding at even radial slot positions of the first slot are electrically connected in series with the arms of the hairpin winding at odd radial slot positions of the second slot connected to form a second phase winding branch, and the first phase winding branch and the second phase winding branch are electrically connected in parallel.

The stator assembly according to the first aspect of the invention may be primarily beneficial because the arms of the hairpin windings are located at odd radial slot positions of the first slot of the pair and the even radial slot positions are located at the second slot of the pair. The arms of the hairpin windings are electrically connected in series to form a first phase winding branch, the arms of the hairpin windings located at the even-numbered radial slot positions of the first slot and the hairpin windings located at the odd-numbered radial slot positions of the second slot. The arms of the clip winding are electrically connected in series to form a second phase winding leg, and the first and second phase winding legs are electrically connected in parallel.

In particular, by dividing the phase winding into first and second phase winding branches electrically connected in parallel, the level of the induced voltage in the phase winding is reduced due to back EMF and armature reactance to make operation compatible with the available supply voltage . However, in the case where the first phase winding branch includes all the arms arranged in the first slot of the slot pair and the second phase winding branch includes all the arms arranged in the second slot of the slot pair, the first and There may be a phase difference between the induced operating voltages between the second slots.

By including the arms of the hairpin windings disposed in the first and second slots of each phase winding leg, the phase difference of the induced operating voltage between the first and second slots can be reduced or eliminated. However, the first phase winding branch includes the arms of the hairpin windings in a first subset of radial slot locations, and the second phase winding branch includes hairpins in a second subset of radial slot locations In the arrangement of the arms of the winding, there may be uneven current flow through the first and second phase winding branches. In particular, radial slot locations located closer to the motor rotor in use may have additional induced voltages caused by additional leakage flux. This can lead to unbalanced resistances and inductances, for example where the first phase winding branch only includes arms located at certain eg inner radial slot locations, and the second phase winding branch only comprises at some other eg outer radial slot locations position of the arm in the arrangement. This can cause additional circulating currents or AC losses due to the current imbalance in each path.

The first and second phase winding legs may have more balanced back EMF, resistance and inductance by including arms of hairpin windings disposed in odd and even radial slot locations in the first and second phase winding legs, Therefore, circulating copper losses can be reduced.

For a given input current, reducing circulating currents and AC losses in the windings can improve motor efficiency and/or thermal performance.

Each of the first phase winding branch and the second phase winding branch may include a hairpin winding having N/2 radial slot locations in the first slot and N in the second slot. /2 arms at radial slot locations. Each of the first phase winding branch and the second phase winding branch may include a hairpin winding having arms located at each of the N radial slot locations, eg simultaneously across each of the first slot and the second slot. N/2 arms in the first slot may be electrically connected in the first phase winding leg, and N/2 arms in the first slot may be electrically connected in the second phase winding leg. N/2 arms in the second slot may be electrically connected in the first phase winding leg, and N/2 arms in the second slot may be electrically connected in the second phase winding leg.

Each of the first and second slots may have N arms of the hairpin winding in N radial slot positions, eg, such that a single arm of the hairpin winding is disposed in a single radial slot position.

The first subset of arms located in the first slot may include arms having a first cross-sectional area. The first subset of arms may be distributed over odd and even radial slot positions of the first slot. The second subset of arms located in the first slot may include arms having a second cross-sectional area. The second subset of arms may be distributed over odd and even radial slot positions of the first slot. The third subset of arms located in the second slot may comprise arms of the first cross-sectional area. The third subset of arms may be distributed over odd and even radial slot positions of the second slot. The fourth subset of arms located in the second slot may comprise arms of the second cross-sectional area. The fourth subset of arms may be distributed over odd and even radial slot positions of the second slot. The first cross-sectional area may be larger than the second cross-sectional area.

This may be beneficial because each of the first and second phase winding branches may be formed by arms of first and second cross-sectional areas. Arms of different cross-sectional areas can have different resistances, so utilizing arms of different cross-sectional areas can reduce AC losses by placing arms of specific cross-sectional area at specific radial slot locations.

The first and third subset arms may be located at the first through N/2th radial slot positions of their respective slots, and the second and fourth subset arms may be located at (N/2)+1th through the respective slots. N radial groove location.

This includes the radially outer slot positions in the first to N/2th radial slot positions of each slot, and the (N/2)+1th through Nth radial slot positions of each slot includes the radially inner slot positions situation may be beneficial. In particular, in use, radially inner slot locations may be more prone to flux leakage. Locating arms of smaller cross-sectional area at radially inner slot locations can reduce the induced AC losses in these arms that are caused by slot leakage flux more concentrated at radially inner slot locations. Arms with smaller cross-sectional areas link proportionally less flux and have less inductive AC losses. The consequent splitting of these smaller cross-sectional area arms can be used to reduce or eliminate the possibility of circulating currents and losses within the phase path. Here, radially outer slot positions may be considered to be slot positions located at a greater radial distance from the center of the stator assembly than radially inner slot positions.

The N radial slot positions may extend from the radially outer slot positions to the radially inner slot positions, eg, such that the first radial slot position includes the radially outermost slot position and the Nth radial slot position includes the radially innermost slot position .

N may include even numbers greater than or equal to 4. N can include multiples of 4.

The first and second grooves may be adjacent to each other, eg, such that there are no further grooves between the first and second grooves.

The plurality of slots may form a plurality of slot pairs around the stator body. Adjacent pairs of slots may be spaced around the stator body, eg circumferentially spaced around the stator body, with at least one intermediate slot pair therebetween, the at least one intermediate slot pair corresponding to at least one additional phase winding.

The stator assembly may include at least one additional phase winding. At least one further phase winding may be provided in at least one further pair of slots and may comprise a similar structure as the phase winding. For example, the arms of the hairpin windings at odd radial slot positions of the first additional slot of the additional pair of slots may be connected to the hairpin windings at the even radial slot positions of the second additional slot of the additional slot pair The arms of the hairpin windings are electrically connected in series to form a first additional phase winding leg, and the arms of the hairpin windings located at the even radial slot positions of the first additional slot can be connected with the hairpins located at the odd numbered positions of the second additional slot. The arms of the type winding are electrically connected in series to form a second further phase winding branch, and the first and second further phase winding branches may be electrically connected in parallel.

The stator assembly may include first, second, and third plurality of slot pairs disposed about the stator body, the first plurality of slot pairs may have the first phase winding disposed therein, and the second plurality of slot pairs may have disposed therein of the second phase winding, the third plurality of slot pairs may have the third phase winding disposed therein. The first, second and third phase windings may comprise the same structure, eg with first and second phase winding branches electrically connected in the manner previously described.

The first, second and third plurality of slot pairs may be arranged in a repeating pattern around the stator body, such as such that the first plurality of slot pairs are followed by the second plurality of slot pairs, followed by the third plurality of slot pairs, followed by The first multiple slot pairs, and so on.

According to a fifth aspect of the invention there is provided an electric motor comprising a stator assembly according to the first aspect of the invention.

According to a sixth aspect of the present invention, there is provided an electric vehicle comprising the electric motor according to the second aspect of the present invention.

Where appropriate, preferred features of the various aspects of the invention may apply equally to other aspects of the invention.

Description of drawings

In order to better understand the invention, and to show more clearly how the invention is carried out, the invention will now be described by way of example with reference to the following drawings:

Figure 1 is a schematic perspective view showing a stator assembly according to the present invention;

Figure 2a is a schematic plan view of the stator assembly of Figure 1;

Figure 2b is an enlarged view of section X of Figure 2a;

Figure 2c is a schematic plan view of the stator assembly of Figure 2 when wound;

Figure 3 is a schematic perspective view of a hairpin winding pre-bending for use with the stator assembly of Figure 1;

4 is a table showing the positioning of pre-bent hairpin windings within slots of the stator assembly of FIG. 1;

Figure 5 is a schematic perspective view of a hairpin winding for use with the stator assembly of Figure 1 after bending;

Figure 6a is a schematic view of the stator assembly of Figure 1 with hairpin windings inserted and bent to define radial rows;

Figure 6b is an enlarged view of portion X of Figure 6a;

7 is a table showing the positioning of the connecting portions of the hairpin windings within the radial row after bending;

8 is a table showing the positioning of hairpin winding arms relative to their respective connecting portions;

FIG. 9 is a first schematic diagram illustrating electrical connections of phase windings of the stator assembly of FIG. 1;

FIG. 10 is a second schematic diagram illustrating electrical connections of phase windings of the stator assembly of FIG. 1;

FIG. 11 is a first schematic diagram showing the mechanical and electrical connection of windings for use with the stator assembly of FIG. 1;

Fig. 12 is a schematic diagram showing the radial position of the connecting portion of the hairpin winding arm relative to the slot of the stator assembly of Fig. 1;

13 is a schematic diagram of hairpin arms disposed in pairs of slots of the stator assembly of FIG. 1;

Figure 14 is a schematic diagram showing the electrical connection of the arms in the single slot of Figure 13;

Figure 15a is a schematic diagram showing the electrical connection of the arms of the slot pair of Figure 13;

Figure 15b is a schematic diagram showing the physical location of the hairpin arms in the electrical connection scheme of Figure 15a;

16 is a schematic diagram illustrating a fully wound stator assembly in accordance with the present invention;

Figure 17 is a schematic diagram showing the complete electrical connection of the stator assembly of Figure 16;

Figure 18 is a schematic diagram showing a first additional embodiment of a hairpin arm disposed within the stator of the present invention;

Figure 19 is a schematic diagram showing a second additional embodiment of a hairpin arm disposed within the stator of the present invention;

Figure 20 is a schematic diagram showing a third additional embodiment of a hairpin arm disposed within the stator of the present invention;

FIG. 21 is a schematic diagram of an electric motor including the stator assembly of FIG. 1; and

FIG. 22 is a schematic diagram of an electric vehicle including the motor of FIG. 17 .

Detailed ways

In Figures 1 and 2a-c, a stator assembly 10 according to an embodiment of the present invention is shown, which is isolated without any windings.

The stator assembly 10 has a generally cylindrical stator body 12 and a plurality of slots 14 formed in the stator body 12 . The plurality of slots 14 are generally rectangular in shape, each slot 14 having four radial slot positions 16, 18, 20, 22, a limited number of slots 14 are shown schematically in Figures 2a and 2b, from the stator body 12 The radially outer side is arranged to the radially inner side of the stator body 12 . In this embodiment, there are 60 slots.

The stator assembly 10 is intended to be a stator assembly for a three-phase electric motor. Thus, the windings of the stator assembly 10 are electrically connected to form three-phase windings, commonly referred to as A, B, and C. The slots 14 are arranged in slots 13 surrounding the stator body, each slot 13 corresponding to a specific phase. The slots 13 circulate circumferentially around the stator body 12, so that the first slot 13 corresponds to the A phase, the second slot 13 adjacent to the first slot 13 corresponds to the B phase, and the second slot 13 adjacent to the second slot 13 corresponds to the B phase. The third channel 13 corresponds to phase C, the fourth channel 13 adjacent to the third channel 13 corresponds to phase A, and so on.

The stator assembly 10 is wound using hairpin windings 24 whose general form is shown in FIG. 3 . Each hairpin winding 24 has a first arm 26 and a second arm 28 connected by a generally u- or v-shaped portion 30 . Each hairpin winding 24 has a first connection portion 32 and a second connection portion 34 at the ends of the respective first and second arms 26 and 28 . The connecting portions 32, 34 are bent portions of the arms 26, 28 to form an electrical connection between the hairpin windings 24, and the ends of the connecting portions 32, 34 have no electrically insulating coating. In this embodiment, 120 hairpin windings 24 are used to wind the stator assembly 10 in the following manner.

Each hairpin winding 24 is inserted into the stator assembly 10 such that the first arm 26 of the hairpin winding 24 is located in the first slot 14 and the second arm 28 of the hairpin winding 24 is located in the second slot 14, The second slot 14 is circumferentially spaced from the first slot 14 around the stator body 10 . In the embodiment shown, the slot pitch 14 of the hairpin winding is 6, for example, such that the hairpin winding 24 having the first arm 26 located in the nominal slot 14 labeled "1" has the The corresponding second arm 28 in the nominal slot 14 of "7". It will be appreciated here that the numbering of the slots is such that the numbering increases in a counter-clockwise direction when viewed from the terminal end of the stator assembly, as shown in Figure 2a.

The hairpin windings 24 are inserted into the stator assembly 10 such that the hairpin windings 24 form an outer winding layer 36 and an inner winding layer 38, as schematically shown in Figure 2c. In this embodiment, the hairpin windings 24 of the outer layer 36 have arms 26, 28 of larger cross-sectional area than the hairpin windings 24 of the inner layer 38 for reasons discussed below. However, it should be understood that within the scope of the present invention, hairpin windings of arms having the same cross-sectional area for the outer winding layer 36 and the inner winding layer 38 may also be used.

In the outer winding layer 36 , the hairpin windings 24 are located in the slots 14 such that the first arms 26 are located at the first radial slot locations 16 and the second arms 28 are located at the second radial slot locations 18 . In the inner winding layer 38 , the hairpin windings 24 are located in the slots 14 such that the first arm 26 is located at the third radial slot location 20 and the second arm 28 is located at the fourth radial slot location 22 . Thus, the outer winding layer 36 occupies the first radial slot location 16 and the second radial slot location 18 , while the inner winding layer 38 occupies the third radial slot location 20 and the fourth radial slot location 22 . The position of the arms 26, 28 of the hairpin winding 24 within the slot 14 can be seen in Figure 4, with S designating the slot number and L designating the radial slot location.

The connecting portions 32 , 34 of the hairpin windings extend axially outward from the stator body 12 of the stator assembly 10 when the hairpin windings 24 are located in the slots 14 . To be able to connect the hairpin windings 24 , the connecting portions 32 , 34 of the hairpin windings are twisted/bent such that the connecting portions 32 , 34 are twisted so that the connecting portions 32 , 34 extend in the axial direction of the stator assembly 10 Previously, extending circumferentially around the stator body 12 with respect to the respective arms 26 , 28 . This twisted hairpin winding is shown in isolation in Figure 5, and the positioning of the bent connecting portion is shown in Figures 2b and 6-8. The first connection portion 32 and the second connection portion 34 are twisted in opposite directions, that is, when viewed from the terminal end of the stator assembly 10, the first connection portion 32 is twisted in a clockwise direction, and when viewed from the terminal end of the stator assembly 10, The second connection portion 34 is twisted in a counterclockwise direction.

Assuming that the first arm 26 and the second arm 28 of each hairpin winding 24 are located at different radial slot positions of different slots, this results in the connecting portions 32 , 34 being at different radial slot positions according to the radial slot positions of their respective arms 26 , 28 Sequentially twist in the direction. Accordingly, the first connecting portion 32 of the outer winding layer 36 with the first arm 26 at the first radial slot location 16 is twisted in a clockwise direction. The second connecting portion 34 of the outer winding layer 36 with the second arm 28 at the second radial slot location 18 is twisted in a counterclockwise direction. The first connecting portion 32 of the inner winding layer 38 with the first arm 26 at the third radial slot location 20 is twisted in a clockwise direction. The second connecting portion 34 of the inner winding layer 38 with the second arm 28 at the fourth radial slot location 22 is twisted in a counterclockwise direction.

The connecting portions 32, 34 of each hairpin winding 24 are twisted to the same extent. This gives an arrangement in which the connecting portions 32, 34 are aligned in radial rows 40, each radial row 40 having four radial positions 42, 44, 46, 48, as illustrated in Figures 6a, 6b and 11 Sexually shown. It should be understood that the radial positions of the radial rows 44 that form loop connections may be slightly different than the radial positions of radial rows 44 that do not form loop connections. For example, the input and output connections of each phase winding may be at a first radial position 42 that is radially offset from the first radial positions 42 of the other radial rows 40 .

In this embodiment, the degree of twist is such that each radial row 40 covers a corresponding slot 14 , although those skilled in the art will appreciate that arrangements in which the radial rows 40 are not aligned with the slots 14 are also contemplated.

In this embodiment, the connecting portions 32, 34 are twisted at a pitch of 3 grooves. This results in an arrangement in which, for example, the first connecting portion 32 of the hairpin winding 24 has the first arm 26 at the first radial slot position 16 of the slot 14 marked "1", at a position corresponding to the marking "1" The first radial position 42 of the radial row 40 of slots 14 at "58". The second connecting portion 34 of the same hairpin winding 24 has the second arm 28 at the second radial slot position 18 of the slot 14 marked "7", located radially corresponding to the slot marked "10" Second radial position 44 of row 40 .

Similarly, the second connecting portion 34 of the hairpin winding 24, having the second arm 28 at the second radial slot location 18 of the slot 14 marked "55", is located corresponding to the slot 14 marked "58" The second radial position 44 of the radial row 40 . The radial positions of the connecting portions 32, 34 relative to the radial slot positions of the respective arms 26, 28 can be seen from a comparison of Figures 5 and 7, where R represents the number of radial rows (corresponding to the number of slots S), P represents the radial position (corresponding to the radial slot position L), as can also be seen in FIG. 8 .

Given the positioning of the connecting portions 32, 34, the electrical connections of the hairpin windings 24 to form the three-phase windings will be discussed below with reference to Figures 9-16.

As can be seen from Figures 9 and 10, each phase winding A, B, C has a first phase winding branch 50 and a second phase winding branch 52 electrically connected in parallel. The structure of phase winding A will be discussed below, although those skilled in the art will understand that phase windings B and C have similar structures.

Each phase winding branch 50, 52 consists of a series of four loops electrically connected together in series. Each loop consists of a plurality of hairpin windings 24 and includes hairpin windings 24 which, when connected together, form a loop around the stator body 12 . It is considered here that a loop is formed in which an electrical path can be traced from a first connecting portion 32 at a first radial position 42 of a given radial row 40 to a second connecting portion 32 at a second radial position 44 of the same radial row The connecting portion 34, and vice versa, and wherein the electrical path can be traced from the first connecting portion 32 at the third radial position 46 of a given radial row 40 to the first connecting portion 32 at the fourth radial position 48 of the same radial row 40. Two connecting parts 34 and vice versa. The loop is schematically represented by line shading in Figure 12, which will be described later.

The loops 54, 56, 58, 60 of the first phase winding branch 50 will be described below, although it will be clear later that the loops of the second phase winding branch 52 have a similar structure.

The first loop 54 of the sequence of first phase winding branches 50 utilizes the hairpin windings 24 of the outer winding layer 36 . As briefly mentioned above, the first connecting portion 32 of the hairpin winding 24, having the first arm 26 at the first radial slot position 16 of the slot 14 marked "1", is located corresponding to the first radial slot position 16 of the slot marked "58" ” of the first radial position 42 of the radial row 40 of grooves 14 . This first connection portion 32 serves as a starting point for the first loop 54, and in particular, the starting point may serve as an input connection through which, in use, current is input into the first loop 54, for example from the inverse of an electric motor Inverter (not shown) input. The position of the arms at the start and end of the loop can be seen in Figure 10, while the radial position of the connecting portion can be seen in Figures 11 and 12. FIG. 12 particularly shows the radial position of the connecting portions 32 , 34 with respect to the respective grooves 14 . The line shaded portion of FIG. 12 shows the connecting portions 32 , 34 having the arms 26 , 28 in the same slot 14 , while the dotted hatching shows the connecting portions 32 , 34 having the arms 26 , 28 in the other slot 14 . .

The second connecting portion 34 of the same hairpin winding 24 has the second arm 28 at the second radial slot position 18 of the slot 14 marked "7", located radially corresponding to the slot marked "10" Second radial position 44 of row 40 . The first connecting portion 32 of the next hairpin winding 24 in the first loop 54 has the first arm 26 at the first radial slot position 16 of the slot 14 marked "13", located at the position corresponding to the first radial slot position 16 of the slot marked "13" The first radial position 42 of the radial row of 10" grooves.

This arrangement of hairpins is similarly repeated around the stator body 12 until the first loop 54 terminates in the second connecting portion 34 of the hairpin winding 24 having a second radial slot located in the slot 14 marked "55" The second arm 28 at position 18, the second connecting portion 34 is located at a second radial position 44 corresponding to the radial row 40 of slots 14 marked "58".

Thus, the first loop 54 begins at the first radial position 42 corresponding to the radial row 40 of slots 14 marked "58" and ends at the first radial position 40 corresponding to the radial row 40 of slots 14 marked "58" Two radial positions 44 .

It will be appreciated that this gives an arrangement in which the first and second connecting portions 32 , 34 of the sequential hairpin windings 24 defining the first loop 54 are in the first radial direction of the radial row 40 around the stator body 12 . The location 42 and the second radial location 44 are adjacent to each other. This adjacent arrangement of the connecting portions 32, 34 enables direct welding between the hairpin windings 24 within the first loop 54 to mechanically and electrically connect the hairpin windings within the first loop 54 in series twenty four. Such direct soldering is a relatively direct connection compared to, for example, arrangements requiring intermediate electrical conductors.

The second loop 56 of the sequence utilizes the hairpin windings 24 of the inner winding layer 38 . The first connecting portion 32 of the hairpin winding 24 has the first leg 26 at the third radial slot position 20 of the slot 14 marked "1", located radially corresponding to the slot 14 marked "58" Third radial position 46 of row 40 . This first connecting portion 32 is used as a starting point for the second loop 56 . The second loop 56 is then constructed in a similar manner to the first loop 54 until the second loop 56 terminates at the second connecting portion 34 of the hairpin winding 24 having a fourth diameter located in the slot 14 marked "55" The second arm 28 toward the slot location 22 is located at a fourth radial location 48 corresponding to the radial row 40 of slots 14 labeled "58".

As can be seen from the above, the end of the first loop 54 is located at the second radial position 44 corresponding to the radial row 40 of slots 14 marked "58" and the start of the second loop 56 is located corresponding to the radial row 40 marked "58" The third radial position 46 of the radial row 40 of slots 14 . Since the ends of the first loop 54 and the start of the second loop 56 are located at adjacent radial positions of the same radial row 40, the first loop 54 and the second loop 56 can be directly welded to each other, thereby joining the first loop 54 and the second loop 54 together. Loop 56 is mechanically and electrically connected in series. Such direct soldering is a relatively direct connection compared to, for example, arrangements requiring intermediate electrical conductors. With respect to the connection parts 32, 34 in Figures 11 and 12, the connections between the loops can be seen.

The third loop 58 of the sequence utilizes the hairpin windings 24 of the inner winding layer 38 . The second connecting portion 34 of the hairpin winding 24 has the second arm 28 at the fourth radial slot position 22 of the slot 14 marked "2", located radially corresponding to the slot 14 marked "5" Fourth radial position 48 of row 40 . This second connection portion 34 is used as a starting point for the third loop 58 . The third loop 58 is then constructed in a similar manner to the first loop 54 and the second loop 56, until the third loop 58 terminates at the first connecting portion 32 of the hairpin winding 24, which has the slot marked "8" The first arm 26 of the third radial slot location 20 of 14 is located at the third radial location 46 corresponding to the radial row 40 of slots 14 marked "5".

As can be seen from the above, the end of the second loop 56 is located at the fourth radial position 48 corresponding to the radial row 40 of slots 14 marked "58" and the start of the third loop 58 is located corresponding to the radial row 40 marked "58" The fourth radial position 48 of the radial row 40 of slots 14 . Since the ends of the second loop 56 and the start of the third loop 58 are located in the spaced radial rows 40, direct welding between the second loop 56 and the third loop 58 cannot be made. Electrical conductors 62, commonly referred to as jumpers, are used to bridge the gap, thereby providing an indirect connection between the second loop 56 and the third loop 58, mechanically and electrically connecting the second loop 56 and the third loop 58 in series.

While indirect connections may be considered less beneficial than direct connections, it should be noted that the end of the second loop 56 and the start of the third loop 58 are located at the fourth radial position 48 of their respective radial rows 40 . This enables a relatively direct indirect connection between the second loop 56 and the third loop 58 .

The fourth loop 60 of the sequence utilizes the hairpin windings 24 of the outer winding layer 36 . The second connecting portion 34 of the hairpin winding 24 has the second arm 28 at the second radial slot position 18 of the slot 14 marked "2", located radially corresponding to the slot 14 marked "5" Second radial position 44 of row 40 . This second connecting portion 34 is used as a starting point for the fourth loop 60 . The fourth loop 60 is then constructed in a manner similar to the first loop 54, the second loop 56, and the third loop 58 until the fourth loop 60 terminates at the first connection portion 32 of the hairpin winding 24, which has a position marked as The first arm 26 of the first radial slot position 16 of the slot 14 of the "8" at the first radial position 42 corresponding to the radial row 40 of the slot 14 labeled "5".

As can be seen from the above, the end of the third loop 58 is located at the third radial position 46 corresponding to the radial row 40 of slots 14 marked "5", and the start of the fourth loop 60 is located corresponding to the radial row 40 marked "5" The second radial position 44 of the radial row 40 of grooves 14 . Since the end of the third loop 58 and the start of the fourth loop 60 are located at adjacent radial positions of the same radial row 40, the third loop 58 and the fourth loop 60 can be directly welded to each other, thereby joining the third loop 58 and the fourth loop 60 together. The loop 60 is mechanically and electrically connected in series. Such direct soldering is a relatively direct connection compared to, for example, arrangements requiring intermediate electrical conductors.

Furthermore, since the start of the first loop 54 and the end of the fourth loop 60 are both located at the first radial position 42 of the respective radial row 40, the input and output of the sequence are connected, ie the input of the first phase winding branch 50 and output connections, can be formed at the same radial position, which enables a relatively simple connection arrangement. The start of the first loop 54 and the end of the fourth loop 60 are located in radial rows 40 that are spaced apart from each other, which may further aid ease of connection.

As mentioned above, the second phase winding branch 52 is constructed in a manner generally similar to that of the first phase winding branch 50 . In particular, the second phase winding branch 52 is a sequence of four loops 64, 66, 68, 70 electrically connected together in series. However, as will be appreciated, the loops 64, 66, 68, 70 of the second phase winding branch have different start and end positions than the loops 54, 56, 58, 60 of the first phase winding branch 50, and have positions at Arms 26 , 28 of hairpin winding 24 in different slots 14 .

The first loop 64 of the sequence of second phase winding branches 52 utilizes the hairpin windings 24 of the outer winding layer 36 . The first connecting portion 32 of the hairpin winding 24 has the first arm 26 at the first radial slot position 16 of the slot 14 marked "2", located radially corresponding to the slot 14 marked "59" The first radial position 42 of the row 40 . This first connecting portion 32 is used as a starting point for the first loop 64 . The first loop 64 is then constructed in a similar manner to the first loop 54 of the sequence of the first phase winding branches 50 until the first loop 64 terminates at the second connecting portion 34 of the hairpin winding 24 having The second arm 28 in the second radial slot position 18 of the slot 14 marked "56" is located in the second radial position 44 corresponding to the radial row 40 of slots 14 marked "59".

It is thus clear that the starting point of the first loop 54 of the sequence of the first phase winding branches 50 and the starting point of the first loop 64 of the sequence of the second phase winding branches 52 are at their respective adjacent radial rows 40 . A radial location 42 is adjacent to each other. This enables relatively direct input connections to be made for the first phase winding branch 50 and the second phase winding branch 52 .

The second loop 66 of the sequence of the second phase winding branches 52 utilizes the hairpin windings 24 of the inner winding layer 38 . The first connecting portion 32 of the hairpin winding 24 has the first leg 26 at the third radial slot position 20 of the slot 14 marked "2", located radially corresponding to the slot 14 marked "59" Third radial position 46 of row 40 . This first connecting portion 32 is used as a starting point for the second loop 66 . The second loop 66 is then constructed in a similar manner to the first loop 64 until the second loop 66 terminates at the second connecting portion 34 of the hairpin winding 24 having a fourth diameter labeled "56" at the slot 14 The second arm 28 toward slot location 22 is located at a fourth radial location 48 corresponding to the radial row 40 of slots 14 marked "59".

As can be seen from the above, the end of the first loop 64 is located at the second radial position 44 corresponding to the radial row 40 of slots 14 marked "59", and the starting point of the second loop 66 is located corresponding to the radial row 40 marked "59" The third radial position 46 of the radial row 40 of slots 14 . Since the ends of the first loop 64 and the start of the second loop 66 are located at adjacent radial positions of the same radial row 40, the first loop 64 and the second loop 66 can be welded directly to each other, thereby joining the first loop 64 and the second loop 64 together. Loop 66 is mechanically and electrically connected in series. Such direct soldering is a relatively direct connection compared to, for example, arrangements requiring intermediate electrical conductors.

The third loop 68 of the sequence utilizes the hairpin windings 24 of the inner winding layer 38 . The second connecting portion 34 of the hairpin winding 24 has the second arm 28 at the fourth radial slot position 22 of the slot 14 marked "1", located radially corresponding to the slot 14 marked "4" Fourth radial position 48 of row 40 . This second connecting portion 34 is used as a starting point for a third loop 68 . The third loop 68 is then constructed in a similar manner to the first loop 64 and the second loop 66, until the third loop 68 terminates at the first connecting portion 32 of the hairpin winding 24, which has the slot marked "7" The first arm 26 of the third radial slot location 20 of 14 is located at the third radial location 46 corresponding to the radial row 40 of slots 14 marked "4".

As can be seen from the above, the end of the second loop 66 is located at the fourth radial position 48 corresponding to the radial row 40 of slots 14 marked "59" and the start of the third loop 68 is located corresponding to the radial row 40 marked "59" The fourth radial position 48 of the radial row 40 of slots 14 . Since the ends of the second loop 66 and the start of the third loop 68 are located in the spaced radial rows 40, no direct welding can be made between the second loop 66 and the third loop 68. Electrical conductors 72, commonly referred to as jumpers, are used to bridge the gap to provide an indirect connection between the second loop 66 and the third loop 68, mechanically and electrically connecting the second loop 66 and the third loop 68 in series.

Although an indirect connection may be considered less beneficial than a direct connection, it should be noted that the end of the second loop 66 and the start of the third loop 68 are located at the fourth radial position 48 of their respective radial rows 40 . This enables a relatively direct indirect connection between the second loop 66 and the third loop 68 .

It will also be noted here that the end of the second loop 66 and the start of the third loop 68 of the sequence of the second phase winding leg 52 are located at the end of the second loop 56 and the third loop 58 of the first phase winding leg 52 between the starting points. For example, it can be said that the radial rows of the beginning and the end of the loop with the sequence of the second phase winding legs 52 are nested within the radial row of the beginning and the end of the loop with the sequence of the first phase winding legs 50 . This arrangement may enable the electrical conductors 72 connecting the second loop 66 and the third loop 68 of the second phase winding leg 52 to be nested within the loop connecting the second loop 56 and the third loop 58 of the first phase winding leg 50 within the electrical conductor 62 . This enables connection arrangements with relatively small axial heights.

The fourth loop 70 of the sequence utilizes the hairpin windings 24 of the outer winding layer 36 . The second connecting portion 34 of the hairpin winding 24 has the second arm 28 at the second radial slot position 18 of the slot 14 marked "1", located radially corresponding to the slot 14 marked "4" Second radial position 44 of row 40 . This second connecting portion 34 is used as a starting point for the fourth loop 70 . The fourth loop 70 is then constructed in a manner similar to the first loop 64, the second loop 66, and the third loop 68 until the fourth loop 70 terminates at the first connecting portion 32 of the hairpin winding 24, which has a position marked as The first arm 26 of the first radial slot position 16 of the "7" slot 14 is located at the first radial position 42 corresponding to the radial row 40 of the slot 14 labeled "4".

As can be seen from the above, the end of the third loop 68 is located at the third radial position 46 corresponding to the radial row 40 of slots 14 marked "4", and the start of the fourth loop 70 is located corresponding to the radial row 40 marked "4" The second radial position 44 of the radial row 40 of grooves 14 . Since the end of the third loop 68 and the start of the fourth loop 70 are located at adjacent radial positions of the same radial row 40, the third loop 68 and the fourth loop 70 can be welded directly to each other, thereby joining the third loop 68 and the fourth loop 70 together. Loop 70 is mechanically and electrically connected in series. Such direct soldering is a relatively direct connection compared to, for example, arrangements requiring intermediate electrical conductors.

Furthermore, since the start of the first loop 64 and the end of the fourth loop 70 are both located at the first radial position 42 of the respective radial row 40, the input and output of the sequence are connected, ie the input of the second phase winding branch 52 and output connections, can be formed at the same radial position, which enables a relatively simple connection arrangement. The start of the first loop 64 and the end of the fourth loop 70 are located in radial rows 40 spaced apart from each other, which may further aid ease of connection.

It can also be seen that the end of the fourth loop 60 of the sequence of the first phase winding branches 50 and the end of the fourth loop 70 of the sequence of the second phase winding legs 52 are at the end of their respective adjacent radial rows 40. A radial location 42 is adjacent to each other. This enables relatively direct output connections to be made for the first phase winding branch 50 and the second phase winding branch 52 .

As can be seen from the discussion above, the first phase winding branch 50 and the second phase winding branch 52 are each formed by a hairpin winding 24 having a given slot provided around the stator body 12 Arms 26 , 28 in two slots 14 of pair 19 . Here, slot pair 19 is considered to be a slot spaced apart by a slot pitch of six, although for the particular embodiment shown, it will also be understood that slot pair 19 may be considered a pair of adjacent slots 14 in channel 13 , as shown in Figure 15b. If we consider the slots marked "1" and "7", as shown in Figure 13, then the first phase winding leg 50 has the first 16 radial slot positions and the first 16 radial slot positions provided in the slot 14 marked "1" The first arm 26 in the three radial slot positions 20, and the second arm 28 disposed in the second radial slot position 18 and the fourth radial slot position 22 of the slot 14 marked "7". Similarly, the second phase winding leg 52 has the first arm 26 disposed in the first radial slot position 16 and the third radial slot position 20 of the slot 14 marked "7", and the The second arm 28 in the second radial slot location 18 and the fourth radial slot location 22 of the slot 14 of 1". In Figures 13 to 15, for clarity, arms 26, 28 in slot "1" are labeled a1-a4, while arms 26, 28 in slot "7" are labeled b1-b4.

This electrical connection can be seen more clearly in Figure 15a. It should be understood that the electrical connections shown in Figures 14 and 15a are not full electrical connections of the phase windings, but are schematic diagrams intended to illustrate the electrical connections between the arms provided in the slots of the pair of slots 19.

Thus, it can be said more generally that the arms in the first radial slot position 16 of the first slot 15 of the slot pair 19 and the second radial slot of the second slot 17 of the second slot 17 of the slot pair 19 in the arm and slot pair 19 in the third radial slot position 20 The arms in location 18 and fourth radial slot location 22 are electrically connected in series to define a portion of the first phase winding leg 50, the pair of slots 19 are two circumferentially spaced apart slots 14 that carry the same phase current. Then, the arms in the first radial slot position 16 and the third radial slot position 20 of the second slot 17 of the slot pair 19 and the second radial slot position 18 and the fourth radial slot position 18 of the first slot 15 of the slot pair 19 The arms in the slot locations 22 are electrically connected in series to define a portion of the second phase winding leg 52 . This arrangement is repeated for all pairs of slots 19 around the stator body 12, thereby forming three-phase windings A, B, C.

It can be seen that this electrical connection provides for the hairpin windings 24 of the first phase winding branch 50 and the second phase winding branch 52 distributed between the first slot 15 and the second slot 17 of the slot pair 19 An equal number of arms, while the first phase winding branch 50 and the second phase winding branch 52 each also have respective radial slot positions 16 , 18 , 20 distributed in the first slot 15 and the second slot 17 of the slot pair 19 , 22 equal number of hairpin arms. This electrical connection can provide several benefits. In particular, by dividing each phase winding into two parallel branches, the induced voltage levels in the phase windings are reduced due to back EMF and armature reactance to make operation compatible with the available supply voltage. The formation of each parallel branch of the phase winding by the mixed arms of adjacent slots 14 of slot pairs 13 around the stator body 12 can then reduce or eliminate any phase difference in the induced operating voltage between the slots 14 . Each parallel branch is formed not only by mixing arms from the grooves of each groove pair 19 , but also by mixing arms at each radial groove location 16 , 18 , 20 , 22 . This may reduce or eliminate any variation in inductance and/or resistance between adjacent slots of slot pair 19, and thus may reduce circulating currents and/or AC losses within stator assembly 10 in use.

As briefly mentioned above, by forming the outer winding layer 36 and the inner winding layer 38 from hairpin windings with different arm thicknesses, the reduction of circulating currents and/or AC losses can be further enhanced.

In an embodiment of the invention, the outer winding layer 36 is formed from the hairpin windings 24 having a larger arm cross-sectional area than the hairpin windings 24 forming the inner winding layer 38 . This results in the arrangement of a given slot pair 19 as shown in FIG. 13 . It should be understood that Figure 13 depicts the physical positions of the arms 26, 28 within the slot 14 and that the slots are depicted in increasing numerical order from left to right for clarity.

It can be seen that for a given slot 14 of slot pair 19, the arms at the first radial slot location 16 and the second radial slot location 18 are larger than the arms at the third radial slot location 20 and the fourth radial slot location 22 The arms have a larger cross-sectional area. As shown in Figures 14 and 15, the arms of a given slot are then electrically connected such that one of the arms of the larger cross-sectional area is electrically connected in series with one of the arms of the smaller cross-sectional area to form a first subgroup 74 of slots, The other arm of the larger cross-sectional area is electrically connected in series with the other arm of the smaller cross-sectional area to form a second subgroup 76 of slots. Then, the first slot subgroup 74 and the second slot subgroup 76 are electrically connected in parallel.

Repeating this configuration for each slot of a given phase gives the aforementioned arrangement, where each phase winding branch is formed by a hybrid arm of adjacent slots of a slot pair, each phase winding branch is formed at each radial slot location and each phase winding leg is also formed by mixing arms of different cross-sectional area.

This arrangement may further reduce circulating currents within the stator assembly 10 in use, and thus reduce the AC losses experienced.

Locating a smaller cross-sectional area arm at the radially inner slot location can result in a reduction in AC losses in that arm. The AC loss is proportional to the magnitude of the cross-slot leakage flux enclosed by the physical boundary of the arm, which in turn is proportional to its cross-sectional area given the slot boundary. The AC losses in the arms may be mainly eddy currents reacting to the leakage flux. The strength of the cross-slot leakage flux increases towards the rotor side of the stator, so maximum loss minimization can be achieved by placing a smaller cross-sectional area closer to the rotor. Therefore, by carefully choosing the relative cross-sectional areas, AC losses can be minimized. It was further concluded that the resistance and inductance of any hairpin is proportional to its position in the slot and its cross-sectional area. The connection of these hairpins in parallel paths can cause additional circulating and unbalanced currents to flow between the paths, which can lead to additional losses. To minimize this additional loss, it may be beneficial to ensure that each parallel path has an equal share of hairpins in each cross-sectional area and slot location.

FIG. 17 schematically shows the electrical connections of the stator assembly 10 , wherein the isolated numbers show the hairpin winding numbering according to FIG. 4 , and SXLY represents a given hairpin arm 26 , 28 corresponding to the hairpin winding 24 slot number and radial slot location. It can be seen that each loop consists of five hairpin windings 24, such that each loop has five turns, and each phase A, B, C of the stator assembly 10 has 20 turns.

Further examples of hairpin arm arrangements can be seen in Figures 18 to 20, resulting in an equal number of hairpin arms distributed between the first and second slots of a pair of slots, and each first and second The two-phase winding legs include an equal number of hairpin arms distributed between respective radial slot positions of the first and second slots.

In the arrangement of Figure 18, the slots 14 are provided in channels 300 around the stator body 12, each channel 300 having three slots. For example, the first channel 302 has slots "55", "56" and "57", while the second channel 304 has slots "1", "2" and "3".

Here, the individual grooves within the first channel 302 and the second channel 304 may be considered to form the groove pair 19 . For example, in the embodiment of Figure 18, there are three groove pairs 19 in the first channel 302 and the second channel 304, the grooves "55" and "1", the grooves "56" and "2", and the grooves " 57" and "3". Considering each slot pair 19, it can be seen that there is an equal number of hairpin arms distributed between the slots of the pair, with the line shaded arm representing the first phase winding leg and the dot shaded arm representing the second phase winding leg . It can also be seen that within the slot pair, the arms are evenly distributed between the radial slot locations 16, 18, 20, 22.

For example, considering slot pair 19 of slots "55" and "1", it can be seen that in slot "55" there is an arm in the first phase winding leg 50 at the fourth radial slot location 22, There are arms in the second phase winding branch 52 at the three radial slot locations 20 . Then in slot "1" there are arms in the first phase winding leg 50 at the third radial slot position 20 and arms in the second phase winding leg 52 at the fourth radial slot position 22.

Considering the slot pair 19 of slots "56" and "2", it can be seen that in slot "56", the first phase winding leg 50 at the second radial slot location 18 and the third radial slot location 20 There are arms and there are arms in the second phase winding leg 52 at the first radial slot location 16 and the fourth radial slot location 22 . In slot "2" there are arms in the first phase winding leg 50 at the first radial slot position 16 and the fourth radial slot position 22, and in the second radial slot position 18 and the third radial slot The second phase winding branch 52 at position 20 has an arm.

Considering the slot pair 19 of slots "57" and "3", it can be seen that in slot "57" there is an arm in the first phase winding leg 50 at the first radial slot location 16, and in the second radial There is an arm to the second phase winding branch 52 at slot location 18 . Then in slot "3" there are arms in the first phase winding leg 50 at the second radial slot position 18 and arms in the second phase winding leg 52 at the first radial slot position 16.

Thus, each slot 14 of slot pair 19 is actually the reverse pattern of the other slot 14 of slot pair 19 . As can be seen from the arrangement of the third channel 306 of the slots "7", "8" and "9" shown in Figure 18, which is the same as the arrangement of the slots "55", "56" and "57", for The continuous channel 300 around the body is repeated.

Figure 18 also shows briefly and schematically how the hairpin arms are arranged within the loops forming the phase winding branches in accordance with the previous embodiments.

Those skilled in the art will appreciate that the arrangement shown in Figure 18 may, in practice, require the use of hairpin windings 24 with arms of different lengths. For example, the hairpin arm at the second radial slot location 18 of slot "56" may need to be connected to the hairpin arm at the third radial slot location 20 of slot "1". This connection is typically made over slot "58", which requires a different, ie, shorter, connection extension for slot "56" than the longer connection extension required for slot "1". This arrangement is similar to what is known in the art as "short pitch".

A similar alternative embodiment can be seen in Figures 19 and 20, with three grooves 14 per channel. Those skilled in the art will appreciate that the arrangement shown in Figure 19 may, in practice, require the use of hairpin windings 24 with arms of the same length.

Figure 21 schematically shows a motor 100 comprising a stator assembly 10, the motor 100 comprising a rotor 102 which, in use, rotates relative to the stator assembly 10 when current flows through the phase windings A, B, C. Further details of the motor 100 are not relevant to the present invention and are therefore not described here for the sake of brevity, but will be well known and understood by those skilled in the art.

FIG. 22 schematically shows an electric vehicle 200 including the motor 100 . Again, further details of the vehicle 200 are not relevant to the present invention and are therefore not described here for the sake of brevity, but are well known and understood by those skilled in the art.

Claims (27)

1. A stator assembly for an electric motor, the stator assembly comprising a stator body, a plurality of slots formed in the stator body, and a phase winding comprising a plurality of hairpin windings electrically connected together, the phase winding comprising a first phase winding leg and a second phase winding leg, wherein the plurality of slots form at least one slot pair around the stator body, each slot of the slot pair comprising N radial slot locations, N being an even number, and each radial slot location having an arm of a hairpin winding located therein, wherein the first and second phase winding legs each comprise an equal number of hairpin arms distributed between the first and second slots of the slot pair, each hairpin arm of the first phase winding leg in the first slot being in a radial position corresponding to the hairpin arm of the second phase winding leg in the second slot, and the first and second phase winding legs are electrically connected in parallel.

2. The stator assembly of claim 1 wherein the first and second slots of the slot pair are circumferentially spaced from each other about the stator body, and at least one additional slot is located between the first and second slots.

3. The stator assembly of claim 1 or 2, wherein the hairpin arms of the first phase winding leg are disposed in a first subset of radial slot positions in the first slot, and the hairpin arms of the second phase winding leg are disposed in a second subset of radial slot positions in the second slot, the first subset of radial slot positions corresponding to the second subset of radial slot positions.

4. The stator assembly according to any of the preceding claims, wherein the hairpin arms of the first phase winding branch are disposed in a first pattern within a first slot, the hairpin arms of the first phase winding branch are disposed in a second pattern within a second slot, and the second pattern is opposite the first pattern.

5. The stator assembly of any of the preceding claims, wherein the phase windings are located within a plurality of slots disposed about the stator body, each slot comprising a plurality of adjacent slots, the stator assembly comprises a plurality of slot pairs, and each slot comprises at least one slot of a slot pair.

6. The stator assembly of claim 5, wherein each slot comprises an equal number of hairpin arms distributed between a first phase winding leg and a second phase winding leg.

7. The stator assembly of claim 5 or claim 6, wherein each slot comprises N hairpin arms in a first phase winding branch and N hairpin arms in a second phase winding branch.

8. The stator assembly of any of claims 5-7, wherein each slot includes an equal number of hairpin arms distributed between respective radial slot positions of slots within the slot.

9. The stator assembly of claim 8, wherein each slot comprises N hairpin arms of a first phase winding leg distributed over each of N radial slot positions, and each slot comprises N hairpin arms of a second phase winding leg distributed over each of N radial slot positions.

10. The stator assembly of any of the preceding claims, wherein the plurality of hairpin windings includes a first set of hairpin windings having a first cross-sectional area and a second set of hairpin windings having a second cross-sectional area, wherein the first cross-sectional area is greater than the second cross-sectional area.

11. The stator assembly of claim 10, wherein the first set of hairpin windings are located radially outward of the second set of hairpin windings.

12. The stator assembly according to any of the preceding claims, wherein a first slot of the slot pair comprises N/2 hairpin arms of a first phase winding branch and N/2 hairpin arms of a second phase winding branch, and a second slot of the slot pair comprises N/2 hairpin arms of the first phase winding branch and N/2 hairpin arms of the second phase winding branch.

13. The stator assembly according to any of the preceding claims, wherein the hairpin arms at odd-numbered radial slot positions of a first slot are electrically connected in series with the hairpin arms at even-numbered radial slot positions of a second slot of a pair of slots to form a first phase winding leg, and the hairpin arms at even-numbered radial slot positions of the first slot are electrically connected in series with the hairpin arms at odd-numbered radial slot positions of the second slot to form a second phase winding leg.

14. An electric motor comprising a stator assembly according to any of the preceding claims.

15. An electric vehicle comprising an electric motor according to claim 14.

16. A stator assembly for an electric motor, the stator assembly comprising a stator body, a plurality of slots formed in the stator body, and a phase winding comprising a plurality of hairpin windings electrically connected together, the phase winding comprising a first phase winding leg and a second phase winding leg, wherein the plurality of slots form at least one slot pair around the stator body, each slot of the slot pair comprising N radial slot locations, N being an even number, each radial slot location having a wall of the hairpin winding located therein, and wherein arms of the hairpin windings located in odd radial slot locations of a first slot of the slot pair are electrically connected in series with arms of the hairpin windings located in even radial slot locations of a second slot of the slot pair to form a first phase winding leg, arms of the hairpin windings located in even radial slot locations of the first slot being electrically connected in series with arms of the hairpin windings located in odd radial slot locations of the second slot, to form a second phase winding branch and the first and second phase winding branches are electrically connected in parallel.

17. The stator assembly of claim 16, wherein a first subset of the arms in the first slot comprise arms of a first cross-sectional area, a second subset of the arms in the first slot comprise arms of a second cross-sectional area, a third subset of the arms in the second slot comprise arms of the first cross-sectional area, and a fourth subset of the arms in the second slot comprise arms of the second cross-sectional area.

18. The stator assembly of claim 17, wherein the first subset of arms and the third subset of arms are located at first through N/2 radial slot positions of their respective slots, and the second subset of arms and the fourth subset of arms are located at (N/2) +1 through N radial slot positions of their respective slots.

19. The stator assembly of any of claims 16-18, wherein the N radial slot positions extend from a radially outer slot position to a radially inner slot position such that a first radial slot position comprises a radially outermost slot position and an nth radial slot position comprises a radially innermost slot position.

20. The stator assembly of any of claims 16-19, wherein N comprises an even number greater than or equal to 4.

21. The stator assembly of any of claims 16-20, wherein the first and second slots are adjacent to each other.

22. The stator assembly of any of claims 16-21, wherein the plurality of slots form a plurality of slot pairs around the stator body, and adjacent slot pairs are spaced around the stator body, at least one intermediate slot pair being located between adjacent slot pairs.

23. The stator assembly of any of claims 16-22, wherein the stator assembly comprises at least one additional phase winding disposed in at least one additional slot pair.

24. The stator assembly of any of claims 16-23, wherein the stator assembly comprises a first plurality of slot pairs disposed about the stator body, the first plurality of slot pairs having a first phase winding disposed therein, a second plurality of slot pairs having a second phase winding disposed therein, and a third plurality of slot pairs having a third phase winding disposed therein.

25. The stator assembly of claim 24, wherein the first, second, and third pluralities of slot pairs are arranged in a repeating pattern around the stator body.

26. An electric motor comprising a stator assembly according to any of claims 16 to 25.

27. An electric vehicle comprising an electric motor according to claim 26.

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