Stator with slot bridges

Abstract

This invention provides a stator with slot bridging elements, comprising a stator core and windings disposed on the stator core. The stator core defines an axial direction, a first end, and a second end of the stator. The stator core includes an outer diameter wall and a plurality of teeth extending radially inward from the outer diameter wall, defining a plurality of slots between the teeth. A plurality of bridging elements are positioned in the plurality of slots, each of the plurality of bridging elements extending across the circumferential width of an associated slot. The outer diameter wall, the plurality of teeth, and the plurality of bridging elements are all composed of a magnetically conductive material. The winding arrangement includes a plurality of conductors located in the slots, each of the plurality of conductors being radially outside one of the bridging elements located in an associated slot.

Description

Technical Field

[0001] This disclosure relates to the field of electric motors, and more specifically to stator arrangements for electric motors. Background Technology

[0002] Many electric motors are designed to operate over a wide speed range. These motors may suffer from significant AC losses during operation, leading to motor inefficiency. They may also experience unwanted noise, vibration, and harshness (NVH), further contributing to motor inefficiency and problems. AC losses and NVH issues are common in many electric motors, including those with integrated permanent magnet (IPM) motors.

[0003] Figure 8 An exemplary rotor and stator arrangement for an IPM motor 110 is shown. For simplicity, Figure 8 Only a limited portion of the rotor and stator arrangement is shown (i.e., a 45° span). For example... Figure 8 As shown, the IPM motor 110 includes a rotor 112 having a plurality of permanent magnets 114 embedded in a cavity within the rotor 112. The rotor 112 is surrounded by a stator 120. The stator 120 includes a stator core 122 on which a winding arrangement 130 is arranged. The stator core 122 includes a plurality of teeth 124, with slots 126 formed between these teeth 124. Conductors of the winding arrangement 130 extend through the slots 126 of the stator core 122. Current flowing through the winding arrangement 130 causes the rotor 112 to rotate about a central axis 11.

[0004] IPM motors exhibit high core losses even under no-load, non-operating conditions. In addition to mechanical losses, core losses also act as additional resistance losses. No-load core losses in IPM motors can account for up to 60% of total resistance losses. At high speeds, AC copper losses and core losses are typically the main losses that tend to reduce the motor's high-speed continuous power. High-speed continuous power is important for the performance of battery-powered electric vehicles (BEVs) and is often a significant requirement for the secondary drive unit in BEVs.

[0005] The main factors causing IPM motor noise are related to the stator structure. Increasing stator stiffness is a proven effective method for reducing motor noise. However, further reductions in motor noise are still needed.

[0006] In light of the foregoing, it is desirable to provide an improved motor that enhances motor performance by reducing high core losses within the motor. Reducing AC losses and NVH (noise, vibration, and harshness) within the motor would be particularly advantageous. It would also be beneficial if the improved motor could be used in battery electric vehicles (BEVs) to help provide high-speed continuous power. Summary of the Invention

[0007] In at least one embodiment, the stator for the motor includes a stator core and windings disposed on the stator core. The stator core defines an axial direction, a first end, and a second end of the stator. The stator core includes an outer diameter wall and a plurality of teeth extending radially inward from the outer diameter wall, defining a plurality of slots between the teeth. A plurality of bridging members are positioned in the plurality of slots, each of the plurality of bridging members extending across the circumferential width of an associated slot. Each of the outer diameter wall, the plurality of teeth, and the plurality of bridging members is composed of a magnetically conductive material. The winding arrangement includes a plurality of conductors located in the slots, each of the plurality of conductors being radially outside one of the plurality of bridging members located in an associated slot.

[0008] In at least one embodiment, the motor includes a rotor and a stator separated from the rotor by an air gap. The stator includes a stator core having a plurality of teeth with a plurality of slots formed between the teeth. A plurality of bridging members are positioned in the plurality of slots. A concave recess is formed on the radially inner side of each of the plurality of bridging members, and a conductor cavity is formed on the radially outer side of each of the plurality of bridging members. A winding arrangement is formed on the stator core, the winding arrangement including a plurality of conductors extending through the conductor cavities.

[0009] In at least one embodiment, the stator core includes a plurality of teeth with a plurality of slots formed between them. A plurality of bridging members are positioned in the plurality of slots, each of the plurality of bridging members extending between two adjacent slots. A concave recess is formed on the radially inner side of each of the plurality of bridging members, and a conductor cavity is formed on the radially outer side of each of the plurality of bridging members.

[0010] The above-described features and advantages, as well as other features and advantages, will become more apparent to those skilled in the art upon reference to the following detailed description and accompanying drawings. While it is desirable to provide a stator for an electric motor having one or more of these or other advantageous features (which will be apparent to those who consult this disclosure), the teachings disclosed herein extend to those embodiments that fall within the scope of the appended claims, regardless of whether they include or implement one or more of the advantages or features mentioned herein. Attached Figure Description

[0011] Figure 1 A plan view of a finite portion of the stator core, including bridging elements located in slots, is shown.

[0012] Figure 2 It shows Figure 1 An external perspective view of the stator core;

[0013] Figure 3 It shows Figure 1An internal three-dimensional view of the stator core;

[0014] Figure 4 It shows Figure 1 An external perspective view of a first alternative embodiment of the stator core;

[0015] Figure 5 It shows Figure 4 An internal perspective view of a first alternative embodiment of the stator core, in which hidden lines show the positioning of the bridging member in the slot;

[0016] Figure 6 It shows Figure 1 A plan view of a second alternative embodiment of the stator core;

[0017] Figure 7 It shows Figure 1 A plan view of a third alternative embodiment of the stator core; and

[0018] Figure 8 A plan view of a prior art IPM motor is shown. Detailed Implementation

[0019] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein feasible embodiments are illustrated by way of illustration. It should be understood that other embodiments may be utilized, and structural or logical changes may be made without departing from the scope of this disclosure. Therefore, the following detailed description should not be considered limiting, and the scope of the embodiments is defined by the appended claims and their equivalents.

[0020] This document discloses a stator assembly 20 for an electric motor, comprising a stator core 22 on which a winding arrangement 50 is positioned. The stator core 22 includes a plurality of teeth 24, with slots 26 formed between these teeth 24. Conductors 52 of the winding arrangement 50 extend through the slots 26. The stator core also includes a slot bridging member 40 extending across the slots 26. The slot bridging member is located radially inward of the conductors 52 of the winding arrangement. In at least one embodiment, the slot 26 is a semi-open slot, and the slot bridging member 40 is further located radially outward of a miniature cap 30 positioned at the end of the teeth 24.

[0021] Stator core with slot bridge connector

[0022] Now for special reference Figures 1 to 3 The stator core 22 is provided by an integral structure that forms around a central axis (i.e., from...). Figure 1 The page has axes extending outwards and inwards, but due to space constraints, the central axis itself is not located on... Figure 1The stator core is a generally cylindrical component defined by (as shown in the diagram). It is composed of a magnetically permeable material, such as ferromagnetic or other materials, including iron, nickel, cobalt, and various alloys and steels containing these elements. It should be understood that the term "magnetically permeable material" refers to any of the aforementioned materials or other materials with high magnetic permeability, and that those skilled in the art will find these materials advantageous for use in conjunction with the stator core.

[0023] In many embodiments, the stator core 22 is formed of sheets of material stacked on top of each other and adhered or otherwise joined together to form a so-called "lamination stack". However, in at least some embodiments, the stator core 22 is composed of an integral structure (e.g., a molded structure). The axial direction on the stator is defined as the direction parallel to the central axis; the radially inward direction is defined as the direction toward the central axis of the stator core 22; the radially outward direction is defined as the direction away from the central axis; and the circumferential direction is defined as the direction of movement about the central axis. The axial direction in... Figure 1 Point 10 is shown in the center, representing the axes extending outwards and inwards from the page. The radial direction is... Figure 1 The middle part is represented by a line segment with a double arrowhead (12). The circumferential direction is... Figure 1 The middle is represented by an arc with a double arrowhead 14. Although in Figure 1 The central axis is not shown, but it should be understood that the central axis of the stator core is located at... Figure 8 The center is shown by the "z" axis 11 (where Figure 8 The "x" and "y" axes in the diagram represent the radial direction.

[0024] Continue to refer to Figures 1 to 3 The stator core 22 includes a plurality of core slots 26 (or simply “slots”) formed between a plurality of teeth 24. The teeth 24 extend radially inward from the circumferential outer diameter wall 23 of the stator core 22. The core slots 26 extend between the outer diameter wall 23 and slot openings formed at the circumferential inner diameter surface 25 of the stator core (i.e., the inner diameter surface 25 defined at the ends of the teeth 24). The core slots 26 and teeth 24 also extend along an axial direction 10 parallel to the central axis of the stator core 22 between a first axial end 28 and a second axial end 29 of the stator core (i.e., the first end 28 opposite the second end 29 of the stator core in the axial direction). The core slots 26 and associated teeth 24 are equidistantly spaced around the circumferential inner diameter surface 25 of the stator core 22, and the respective inner surfaces of the teeth 24 extend axially parallel to the central axis.

[0025] In at least some embodiments, each tooth 24 of the stator core includes a microcap 30 positioned on the radially inner end of the tooth 24. The microcap 30 is a circumferentially outwardly extending protrusion / projection at the radially inner end of each tooth 24 on opposite sides of the tooth 24. This protrusion may also be referred to as a "foot" at the end of the tooth. Pairs of opposing microcaps 30 on adjacent slots form entrances to the slots, these entrances forming semi-closed slot openings 32 (which may also be referred to as "semi-open" slots). Therefore, the circumferential width of each slot 26 is smaller at the microcap 30 than at a more radially outward position and / or at the center of the slot 26. For example, as... Figure 1 As shown, the width of each slot 26 along the circumferential inner surface 25 of the stator core 22 is less than “w1” at the slot opening 32, and equal to “w1” as shown at a more central location in the slot 26. An exemplary description of such a stator core with a microcap is described in U.S. Patent Publication No. 2024-0275228-A1 (U.S. Application No. 18 / 441,426), published August 15, 2024, the entire contents of which are incorporated herein by reference.

[0026] A slot bridging member 40 is positioned in each slot. Each slot bridging member 40 is provided by a thin segment of magnetically conductive material extending between two adjacent teeth 24 forming the slot 26. Therefore, the circumferential width of the slot bridging member 40 is equal to the circumferential width of the slot itself (i.e., w1), but its radial thickness dimension (d1) is much smaller than the circumferential width (w1). For example, in at least some embodiments, w1 is five to twenty times d1. Furthermore, when the stator core 22 is provided by a laminated stack, the radial thickness d1 of each of the plurality of bridging members 40 can be between approximately 1.5 and 2 times the thickness of one lamination of the laminated stack (e.g., within a tolerance of + / - 15% of 1.75 times the thickness of one lamination). Furthermore, in at least some embodiments, 0.3 mm ≤ d1 ≤ 0.6 mm.

[0027] exist Figures 1 to 3 In one embodiment, the slot bridging member 40 extends circumferentially between adjacent teeth 24, without any radial component other than the radial thickness dimension (d1) of the bridging member 40. Therefore, it will be appreciated that the slot bridging member 40 can be arcuate and generally defined along a radius relative to the central axis of the stator core. In at least one embodiment, the slot bridging member is not arcuate but extends in a straight line between two teeth 24. However, in other embodiments, the slot bridging member 40 also includes some radial component, for example, in conjunction with the following... Figure 6 and Figure 7 The components are described in further detail.

[0028] In addition to having circumferential dimensions (w1) and radial dimensions (d1), it will also be noted that the slot bridge 40 has an axial dimension. Figures 1 to 3 In one embodiment, the slot bridging member extends axially for the full length of each slot 26 of the stator core (i.e., between the first end 28 and the second end 29). However, it will be appreciated that in at least some embodiments, the axial extension of the slot bridging member 40 is less than the entire axial length of the slot, as described below. Figure 4 and Figure 5 The implementation method is explained in further detail.

[0029] Continue to refer to Figures 1 to 3 As can be seen from the implementation, the slot bridging member 40 is located radially inside the conductor 52 of the winding arrangement 50 within the slot 26, but radially outside the end of the tooth 24 along the inner diameter surface 25. Specifically, the slot bridging member 40 is located radially outside the miniature cap 30 within the slot. Therefore, each slot bridging member 40 is radially distanced "r1" from the inner diameter surface 25 within the slot 26, where r1 is greater than the maximum radial dimension of the miniature cap 30 at the end of the slot 26.

[0030] The slot bridging member 40 can be disposed in the slot in different configurations. In at least one embodiment, the slot bridging member 40 is integrally formed with the tooth 24. Thus, each layer of the lamination stack providing the stator core 22 can be stamped or otherwise formed to include the slot bridging member 40 extending between the teeth 24. Alternatively, in at least one embodiment, the slot bridging member 40 can be provided by a separate segment of the magnetic material added to the stator core 22 after the teeth are formed. For example, the slot bridging member 40 can be a separate / independent piece from the teeth 24 of the stator core 22, which are adhered, welded, friction-fitted, or otherwise arranged in the slot 26, wherein each slot bridging member extends between two adjacent teeth 24 of the stator core 22.

[0031] Slot bridging connectors advantageously connect adjacent stator tooth pairs and offer several benefits. For example, each slot bridging connector 40 creates a short-circuit path for electromagnetic flux to flow between adjacent pairs of stator teeth. Therefore, slot bridging connectors can also be referred to as “short-circuit bridging connectors.” As explained in further detail herein, these short-circuit bridging connectors 40 can advantageously reduce core losses, reduce leakage flux entering the stator core slots to reduce AC copper losses, and reduce noise within the motor by providing a more robust stator structure.

[0032] Winding arrangement on the stator core

[0033] As described above, a winding arrangement 50 is provided on the stator core 22. The winding arrangement 50 consists of a plurality of conductors 52 extending axially through the slots 26. For simplicity, only... Figure 1Conductor 52 is shown in one of the slots. However, it will be appreciated that conductor 52 is also located in other slots 26 of the stator core 22. End turns (not shown) connect conductor 52 in different slots. The slot conductors 52 and the end turns together form the complete winding arrangement of the stator 20.

[0034] The conductors 52 and end turns used to secure the winding arrangement 50 can be provided by any of the various wires and wire segments commonly used to form motor windings. For example, the winding arrangement can be provided by segmented conductors (or “hairpin” conductors) inserted into slots 26 in the axial direction. An exemplary description of a winding arrangement formed by segmented conductors is described in U.S. Patent Publication No. 2023 / 0396115 (U.S. Application No. 18 / 325,535), the entire contents of which are incorporated herein by reference.

[0035] In at least one embodiment, the conductor 52 in the groove is a copper wire or wire segment having a generally rectangular shape. The conductor 52 may be insulated with an insulating coating (e.g., a polymer such as PVC or other materials). Although in Figure 1 The diagram shows a generally rectangular conductor, but it should be recognized that any conductor of various shapes, sizes, and forms can be used in slot 26, as is common in the formation of stator windings, such as circular conductors. Conductors 52 can be arranged in a single column in each slot 26. For example, in at least some embodiments, six or eight conductors can extend through each slot, arranged in a single column, where each conductor is associated with a “layer” of conductors within the slot. The width of each conductor 52 is less than the width of the associated slot (e.g., less than...). Figure 1 (The dimension “w1” in the text).

[0036] Alternative implementation methods for trough bridge connectors

[0037] Now for reference Figure 4 and Figure 5 In at least one alternative embodiment of the stator core 22, the slot bridging member 40 may have a finite axial dimension (i.e., a finite axial depth) such that the slot bridging member 40 extends less than the entire axial length of the slot 26. For example, each slot bridging member 40 may extend only half the axial depth of the associated slot 26 in the axial direction. This embodiment in Figure 4 and Figure 5 The image is illustrated by slot bridging members 40a and 40b. In this embodiment, some slot bridging members 40a are positioned on the upper / first axial half of the stator core 22, and other slot bridging members 40b are positioned on the lower / second axial half of the stator core. The distribution of slot bridging members 40a and 40b between the first and second axial halves of the stator core 22 may be equal or unequal, but the spacing between the slot bridging members is consistent. For example, in... Figure 4 and Figure 5 In this embodiment, the number of slot bridges 40b on the second axial half of the stator core is twice the number of slot bridges 40a on the first half of the stator core, but both slot bridges 40a and 40b are evenly spaced around the stator core (e.g., in a 1-2-1-2 pattern between the first and second halves of the stator core). This consistent spacing of the slot bridges 40a and 40b creates an arrangement that, depending on the application, can advantageously strengthen the stator to reduce noise and can also provide reduced flux leakage and reduced core losses.

[0038] Now for reference Figure 6 and Figure 7 In at least some alternative embodiments of the stator core 22, the slot bridging members 40 are particularly arcuate and / or angled. In these embodiments, the slot bridging members 40c are neither linear nor follow a circumferential arc, depending on their distance from the central axis of the stator core. Instead, the slot bridging members 40c have a particular / unique shape. For example, the central segment 42 of each slot bridging member 40c may be particularly arcuate based on an arc radius much smaller than the distance of the slot bridging member 40c from the central axis (e.g., the arc radius of the central segment 42 may be defined by a distance less than half the distance from the central axis). Furthermore, the opposite sides 44, 46 of the central segments 42 may each be linear individually, but angled relative to each other. Figure 6 In an exemplary embodiment, the central section 42 is specifically arc-shaped, and the first circumferential side 44 of the slot bridge 40 is angled relative to the second circumferential side 46 of the slot bridge. Figure 7 In an exemplary embodiment, the central section 42 of the slot bridge 40d is also specifically arc-shaped, but based on the radius ratio Figure 6 Its radius is small. Furthermore, in Figure 7 In an exemplary embodiment, the first side 44 is angled to a greater extent than the second side 44 (e.g., closer to 90°). Furthermore, in Figure 7 In an exemplary embodiment, the first side 44 and the second side of the slot bridge connector 40d taper slightly as they move away from the tooth 24 and toward the central section 42 of the slot bridge connector 40c.

[0039] Continue to refer to Figure 7 In at least one alternative embodiment, the end of each slot bridge 40d is connected to the radially inner end of the adjacent tooth. In this embodiment, the distance r1 is zero. The slot bridges 40d are angled such that concave recesses / cavities 48 are sequentially formed along the inner diameter 25 of the stator core. These recesses 48 are arranged at the ends of the slots 26 and extend toward the slots in a radially outward direction. In other words, in other embodiments where the slots are semi-enclosed, the recesses 48 are located at positions where openings to the slots will be provided. Figure 7 This arrangement can also be viewed as an implementation in which slot bridges are used to connect microcaps, thereby forming a single structure extending across the slots. This is Figure 6 The slotted bridge connector is an alternative to the implementation of the miniature cap.

[0040] exist Figures 1 to 7 In each embodiment, it will be appreciated that the slot bridging member 40 divides the slot 26 into two distinct portions. First, each slot bridging member 40 defines a conductor cavity 51 on its radially outer side (i.e., a cavity 51 defined between the slot bridging member 40 and the circumferential outer diameter wall 23). Second, each slot bridging member 40 defines a concave recess 41 in the associated slot 26 on its radially inner side (i.e., a recess extending from the inner diameter surface 25 toward the circumferential outer diameter wall 23). In some embodiments, the concave recess is larger than the other concave recesses. For example, in Figure 7 In the implementation method, with Figure 1 Compared to the concave recess, the concave recess 41 is relatively smaller. More specifically, in Figure 7 In one embodiment, the relatively small pit 48 is used as a concave recess 41.

[0041] Operation of motors including stators with slot bridges

[0042] It will be appreciated that the disclosed stator assembly can be used in an electric motor. Specifically, stator assembly 20 can be used in an electric motor, wherein stator assembly 20 is separated from the rotor by an air gap. The rotor can be any of various types of rotors, for example... Figure 8 The rotor 112 of the IPM motor is shown. However, it will be appreciated that the stator assembly 20 can also be used for other types of motors, such as induction motors. In at least one application, the stator assembly 20 is particularly advantageous when used as a secondary drive unit in a BEV.

[0043] As previously described, stator assembly 20 advantageously provides loss reduction and NVH improvement compared to conventional stator designs. This loss reduction is particularly useful for secondary drive unit applications. The bridging elements 40 in the stator design are advantageous in at least three ways: (1) they create short-circuit paths for electromagnetic flux, which can be used to reduce core losses; (2) they reduce leakage flux entering the slots, thereby reducing AC copper losses; and (3) they utilize a more robust stator structure to reduce noise. Furthermore, the NVH reduction provided by the embodiments described herein allows the motor to operate efficiently over a wide range of operating speeds. This loss reduction is significant during a typical drive cycle of the secondary drive unit iDM (Integrated Drive Module).

[0044] In addition to the advantages mentioned above, additional benefits will be recognized. For example, stator assembly 20 is configured to reduce leakage flux into the slots and copper conductors, and specifically to reduce leakage flux under no-load and light-load conditions. The bridging member 40 of the stator assembly provides additional structural support to the stator core, thereby reducing NVH (noise, vibration, and harshness). The bridging member 40 extends across the slots while still enabling complete oil cooling within the slots 26, and no additional seals are required in the slots. When used in conjunction with segmented conductors, the bridging member also provides support for the segmented conductors.

[0045] In testing, stator assembly 20 showed a reduction of over 10% in core losses and resistance losses under no-load conditions. The stator assembly also showed a 10% reduction in AC copper losses under sinusoidal input conditions and a 15% reduction under PWM (pulse width modulation) loss input conditions. Exemplary NVH benefits were also demonstrated in testing, including a reduction of up to 5 dB in equivalent radiated power (ERP) observed at the main mechanical orders (orders 24, 48, and 72). This reduction can be attributed at least in part to the increase in stiffness in the tangential direction. The benefits may be even greater for induction motors, where the electromagnetic force in the tangential direction contributes more to noise and vibration levels than in IPM motors.

[0046] Although various embodiments of stator assemblies with slotted bridges have been described herein, those skilled in the art will understand that other implementations and modifications are possible. Furthermore, aspects of the various embodiments described herein can be combined with or replaced by aspects from other features to arrive at embodiments different from those described herein. Therefore, it should be understood that the various features and functions disclosed above and others, or alternatives thereof, can be voluntarily combined into many other different systems or applications. Those skilled in the art can subsequently make various substitutions, modifications, variations, or improvements therein that are not currently foreseen or anticipated, and these are also intended to be covered by any final appended claims.

Claims

1. A stator for an electric motor, comprising: A stator core, defining an axial direction, a first end, and a second end, the stator core comprising: Outer diameter wall; A plurality of teeth extending radially inward from the outer diameter wall, defining a plurality of grooves between the plurality of teeth; and A plurality of bridging members located in the plurality of slots, each of the plurality of bridging members extending across the circumferential width of the associated slot; Each of the outer diameter wall, the plurality of teeth, and the plurality of bridging elements is composed of a magnetically conductive material; and A winding arrangement disposed on the stator core, the winding arrangement comprising a plurality of conductors located in the slots, each of the plurality of conductors being located radially outside one of the plurality of bridging elements located in an associated slot.

2. The stator of claim 1, further comprising a microcap located at the radially inner end of the tooth and extending in a circumferential direction, wherein the microcap defines a semi-open slot, and wherein the bridging member is located radially outer of the microcap.

3. The stator according to claim 1, wherein the plurality of bridging members are integrally formed with the plurality of teeth.

4. The stator of claim 1, wherein the radial thickness of each of the plurality of bridging members is less than the circumferential width of the associated slot.

5. The stator of claim 4, wherein the stator core is provided by a laminated stack, and wherein the radial thickness of each of the plurality of bridging members is between 1.5 and 2 times the thickness of one lamination of the laminated bridging member.

6. The stator according to claim 4, wherein the radial thickness is between 0.3 mm and 0.6 mm.

7. The stator of claim 1, wherein each of the plurality of bridging members has a finite axial depth in an associated slot, the finite axial depth being less than the distance from the first end to the second end of the associated slot.

8. The stator according to claim 7, wherein the plurality of bridging members comprises a first group of plurality of bridging members arranged on a first axial half of the stator core and a second group of plurality of bridging members arranged on a second axial half of the stator core.

9. The stator of claim 1, wherein each of the plurality of bridging members includes a first circumferential side and a second circumferential side, wherein the first circumferential side is angled relative to the second circumferential side.

10. The stator of claim 9, wherein the first circumferential side and the second circumferential side of each bridging member are separated by a central section, wherein the central section is an arcuate section defined by a radius smaller than the distance from the bridging member to the central axis of the stator core.

11. The stator according to claim 9, wherein each bridging member is connected to the radially inner end of an adjacent tooth, and wherein a recess is formed along the inner diameter of the stator core via the bridging member.

12. An electric motor, comprising: Rotor; as well as The stator, separated from the rotor by an air gap, comprises: A stator core, the stator core comprising a plurality of teeth, wherein a plurality of slots are formed between the plurality of teeth; A plurality of bridging members located in the plurality of slots, wherein a concave recess is formed on the radially inner side of each of the plurality of bridging members, and a conductor cavity is formed on the radially outer side of each of the plurality of bridging members; and A winding arrangement formed on the stator core, the winding arrangement comprising a plurality of conductors extending through the conductor cavity.

13. The motor of claim 12, wherein the stator core further comprises a plurality of miniature caps located at the ends of the plurality of teeth, wherein each of the plurality of bridging members is located radially outside an associated pair of miniature caps among the plurality of miniature caps.

14. The motor of claim 12, wherein each of the plurality of bridging members is defined by an axial depth, the axial depth being less than the axial depth of each of the plurality of slots.

15. The motor of claim 12, wherein each of the plurality of bridging members includes a first circumferential side and a second circumferential side, wherein the first circumferential side is angled relative to the second circumferential side.

16. The motor according to claim 12, wherein the motor is an internal permanent magnet (IPM) motor.

17. A stator core, comprising: Multiple teeth, with multiple grooves formed between the multiple teeth; as well as A plurality of bridging elements are located in the plurality of slots, each of the plurality of bridging elements extending between two adjacent slots, wherein a concave recess is formed on the radially inner side of each of the plurality of bridging elements, and a conductor cavity is formed on the radially outer side of each of the plurality of bridging elements.

18. The stator core of claim 17, wherein the plurality of bridging members are integrally formed with the plurality of teeth.

19. The stator core of claim 17, further comprising a plurality of microcaps located at the ends of the plurality of teeth, wherein each of the plurality of bridging members is located radially outside an associated pair of microcaps among the plurality of microcaps.

20. The stator core of claim 17, wherein each of the plurality of bridging members is defined by an axial depth less than the axial depth of each of the plurality of slots.

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