阅读说明：本技术 带有狭槽闭合件的电机 (Electric machine with slot closure ) 是由 安德鲁·卡沙 雅各布·克里赞 唐纯 于 2019-07-09 设计创作，主要内容包括：本公开提供了“带有狭槽闭合件的电机”。一种电机,包括：定子,所述定子具有限定开口狭槽的齿；和狭槽闭合件,其设置在所述狭槽中。每个狭槽闭合件都包括被非磁性壳体包围的磁通桥。所述狭槽闭合件设置在齿中的相邻齿之间,其中所述壳体接合并跨越所述相邻齿。所述壳体分别在所述磁通桥和所述相邻齿之间形成非磁性间隙,以减小扭矩波动的可能性。(The present disclosure provides a "motor with slot closure". An electric machine comprising: a stator having teeth defining open slots; and a slot closure disposed in the slot. Each slot closure includes a flux bridge surrounded by a non-magnetic housing. The slot closure is disposed between adjacent ones of the teeth with the housing engaging and spanning the adjacent teeth. The housing forms a non-magnetic gap between the flux bridge and the adjacent tooth, respectively, to reduce the likelihood of torque ripple.)

1. An electric machine, comprising:

a stator having teeth defining open slots; and

slot closures, each slot closure comprising a flux bridge surrounded by a non-magnetic housing and disposed between adjacent ones of the teeth, wherein the housing engages and spans the adjacent teeth, wherein the housing forms a non-magnetic gap between the flux bridge and the adjacent teeth, respectively, to reduce a likelihood of torque ripple.

2. The electric machine of claim 1, wherein the flux bridge is a first flux bridge and each of the slot closures further comprises a second flux bridge positioned in the housing such that a portion of the housing is disposed between the first and second flux bridges to form another non-magnetic gap between the flux bridges.

3. The electric machine of claim 2 wherein the further non-magnetic gap is angled with respect to a radially inner side of the housing.

4. The electric machine of claim 2, wherein each of the slot closures further comprises a third flux bridge positioned in the housing between the first and second flux bridges such that portions of the housing are disposed between the first and third flux bridges to form a third non-magnetic gap and the second and third flux bridges to form a fourth non-magnetic gap, respectively.

5. The electric machine of claim 4, wherein the third flux bridge has a cross-sectional area that is less than a cross-sectional area of the first flux bridge.

6. The electric machine of claim 1, wherein the flux bridge is encapsulated in the housing.

7. The electric machine of claim 1 further comprising a winding disposed in the slot between the radially outer end of the slot and the slot closure.

8. The electric machine of claim 1 wherein the adjacent teeth each define a recessed portion configured to receive a protrusion of the housing to secure the slot closure in a corresponding one of the slots.

9. An electric machine, comprising:

a stator having radially extending teeth defining slots between adjacent teeth, the slots having slot openings defined between tips of the adjacent teeth; and

slot closures disposed in the slot openings to close the slots, each of the slot closures including a non-magnetic housing spanning an associated one of the slot openings and a flux bridge disposed in the housing, wherein the flux bridge is completely surrounded by the housing.

10. The electric machine of claim 9, wherein a portion of the housing is disposed between one of the adjacent teeth and the flux bridge to form a non-magnetic gap.

11. An electrical machine as claimed in claim 1 or 9, wherein the flux bridges are formed from a ferromagnetic material.

12. The electric machine of claim 1 or 9, wherein the housing is plastic.

13. An electric machine as claimed in claim 1 or 9, wherein the slot closure extends the length of the slot.

14. The electric machine of claim 9, further comprising a rotor supported for rotation within the stator, and wherein a portion of the housing is disposed between the flux bridge and the rotor.

15. A method of assembling a stator, comprising:

providing a stator core having slots with openings;

winding a conductor in the slot;

manufacturing the flux bridge from a ferromagnetic material;

encapsulating the flux bridge in a non-magnetic housing to form a slot closure; and

inserting the slot closure into one of the openings such that the non-magnetic housing forms at least one non-magnetic gap between the flux bridge and stator to reduce the likelihood of torque ripple.

Technical Field

The present disclosure relates to electric motors, and more particularly to electric motors including slot closures.

Background

Vehicles, such as battery electric vehicles and hybrid electric vehicles, include a traction battery assembly to serve as an energy source for the vehicle. The traction battery may include components and systems that help manage vehicle performance and operation. The traction battery may also include high voltage components, and an air or liquid thermal management system for controlling the battery temperature. The traction battery is electrically connected to a motor that provides torque to the driven wheel. Electrical machines typically include a stator and a rotor that cooperate to convert electrical energy into mechanical motion, or vice versa.

Disclosure of Invention

According to one embodiment, an electric machine includes a stator having teeth defining open slots and slot closures disposed in the slots. Each slot closure includes a flux bridge surrounded by a non-magnetic housing. The slot closure is disposed between adjacent ones of the teeth with the housing engaging and spanning the adjacent teeth. The housing forms a non-magnetic gap between the flux bridge and the adjacent tooth, respectively, to reduce the likelihood of torque ripple.

According to another embodiment, an electric machine includes a stator having radially extending teeth defining slots between adjacent teeth. The slot has a slot opening defined between the tips of adjacent teeth. A slot closure is disposed in the opening to close the slot. Each of the slot closures includes a non-magnetic housing spanning an associated one of the openings and a flux bridge disposed in the housing, wherein the flux bridge is completely surrounded by the housing.

According to yet another embodiment, a method of assembling a stator includes: providing a stator core having a slot with an opening; and winding a conductor in the slot. The method further comprises the following steps: manufacturing a flux bridge from a ferromagnetic material; encapsulating the flux bridge in a non-magnetic housing to form a slot closure; and inserting the slot closure into one of the openings such that the non-magnetic housing forms at least one non-magnetic gap between the flux bridge and the stator to reduce the likelihood of torque ripple.

Drawings

Fig. 1 is a schematic view of an electric machine.

Fig. 2 is a perspective view of one end of the stator of the electric machine, showing all winding paths.

Fig. 3 is an axial cross-sectional view of a portion of an electric machine.

Fig. 4 is an enlarged view of the slot closure of fig. 3.

Fig. 5 is a perspective view of a flux bridge.

Fig. 6 is a partial cross-sectional view of another stator.

Fig. 7 is a cross-sectional view of a slot closure according to another embodiment.

Fig. 8 is a cross-sectional view of a slot closure according to yet another embodiment.

Fig. 9 is a flowchart illustrating a method of manufacturing a stator.

Detailed Description

Embodiments of the present disclosure are described herein. However, it is to be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As one of ordinary skill in the art will appreciate, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combination of features shown provides a representative embodiment for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations.

Referring to fig. 1, the electric machine 20 may be used in a vehicle such as an all-electric vehicle or a hybrid electric vehicle. Of course, the motor 20 may also be used in non-vehicular applications. The electric machine 20 may be referred to as an electric motor, a traction motor, a generator, or the like. The motor 20 may be a permanent magnet motor, an induction motor, or the like. The electric machine 20 is capable of functioning as both a motor and a generator.

In a vehicle environment, the electric machine 20 may be powered by the traction battery of the vehicle. The traction battery may provide a high voltage Direct Current (DC) output from one or more arrays of battery cells (sometimes referred to as a battery cell stack) within the traction battery. The battery cell array may include one or more battery cells that convert stored chemical energy into electrical energy. A battery may include a housing, a positive electrode (cathode), and a negative electrode (anode). The electrolyte allows ions to move between the anode and cathode during discharge and then return during recharge. The terminals allow current to flow out of the battery cells for use by the vehicle.

The traction battery may be electrically connected to one or more power electronic modules. The power electronics module may be electrically connected to the electric machine 20 and may provide the ability to transfer electrical energy bi-directionally between the traction battery and the electric machine. For example, a typical traction battery may provide a DC voltage, while the electric machine 20 may require a three-phase Alternating Current (AC) voltage to function. The power electronics module may include an inverter that converts the DC voltage to a three-phase AC voltage according to the requirements of the motor 20. In the regeneration mode, the power electronics module may convert the three-phase AC voltage from the electric machine 20 acting as a generator to the DC voltage required by the traction battery.

Referring to fig. 1 and 2, the motor 20 includes a housing 21 enclosing a stator 22 and a rotor 24. The stator 22 is fixed to the housing 21 and includes a cylindrical core 32 having an inner diameter 28 (which defines the bore 30) and an outer diameter 29. The core 32 may be formed from a plurality of stacked laminations. The rotor 24 is supported for rotation within the bore 30. The rotor 24 may include windings or permanent magnets that interact with the windings of the stator 22 to produce rotation of the rotor 24 when the motor 20 is energized. The rotor 24 may be supported on a drive shaft 26 that extends through the housing 21.

The stator core 32 has teeth 33, the teeth 33 defining slots 34 between adjacent teeth. The slots 34 are circumferentially disposed about the core 32 and extend outwardly from the inner diameter 28. The slots 34 may be equally spaced about the circumference and extend axially from a first end 36 to a second end 38 of the core 32. In the illustrated embodiment, the core 32 defines thirty-six slots, but in other embodiments, the core 32 may include more or fewer slots. The motor 20 includes windings 40, the windings 40 being disposed in the slots 34 of the core 32 between the radially outer ends 42 and the openings of the slots. The windings may be hairpin windings, (as shown) distributed windings or concentrated windings. The winding 40 may include a plurality of phases, e.g., three phases, and each phase may include a plurality of parallel paths. An insulator such as paper may be provided between the winding 40 and the core 32.

Fig. 3 is a partial cross-sectional view of the motor 20 showing four of the slots 34. The slots 34 are referred to as "open slots" because each slot 34 has a slot opening 50 defined between the tips 52 of adjacent teeth. The open slots facilitate manufacture of the stator 22, but increase the likelihood of undesirable torque ripple and other negative characteristics. Previous designs have proposed inserting a metal wedge in the slot opening to fully close the slot, similar to the closed slot design. However, these designs also create undesirable features such as short high permeation paths for magnetization flux that are counterproductive to torque production below rated operating conditions.

Referring to fig. 4, the present application discloses a slot closure 60 that includes both conductive and insulative materials to form a non-magnetic gap within the slot closure 60 to reduce torque ripple and other negative characteristics. In one embodiment, each slot closure 60 includes a housing 62 and one or more flux bridges 64. The housing 62 is formed of a non-magnetic and non-conductive material (e.g., plastic). The flux bridges 64 are bodies of ferromagnetic material (e.g., soft magnetic composite material). The flux bridges 64 are completely contained within the housing 62 such that portions of the housing form a non-magnetic gap between the flux bridges 64 and the teeth 33. As used herein, "non-magnetic gap" does not necessarily refer to a void space, i.e., an air gap, but rather refers to a magnetic void due to the engagement of an insulating material (e.g., air, plastic, etc.) between two or more magnetic components.

In the embodiment shown in fig. 4, each slot closure member 60 includes a first flux bridge 64a and a second flux bridge 64 b. Each of the first and second flux bridges is encapsulated by a housing 62 to enclose the flux bridges 64 in a non-magnetic and non-conductive material. For example, the housing 62 includes a first portion 66 disposed between the flux bridge 64a and the teeth 33a to form a nonmagnetic gap 70. The housing 62 also includes a second portion 68 disposed between the flux bridge 64b and the tooth 33 to form a second nonmagnetic gap 72. A third portion 74 of the housing 62 is disposed between the first flux bridge 64a and the second flux bridge 64b to form a third nonmagnetic gap 76. A radially outer portion 78 of the housing 62 separates the flux bridge 64 from the winding 40 to form a fourth non-magnetic gap 80, and a radially inner portion 82 encloses a radially inner side of the flux bridge 64.

Referring to fig. 4 and 5, each flux bridge 64 may include a prismatic body 90, the prismatic body 90 having opposing end faces 92 and a plurality of side faces extending between the end faces. In the illustrated embodiment, the body 90 includes four sides 94, 96, 98, and 100 and has a generally triangular cross-section. Of course, other geometries are contemplated (see, e.g., fig. 7 and 8). The first flux bridge 64a and the second flux bridge 64b may be the same component disposed in the housing 62 in different orientations. The angled side 96, which is at an acute angle relative to the side 94, allows the flux bridges 64a, 64b to overlap while maintaining the third nonmagnetic gap 76.

The slot closure 60 may be formed by first manufacturing the flux bridge 64 and encapsulating the flux bridge 64 with resin (which hardens to form the housing 62). Alternatively, a fully formed housing 62 may be manufactured, said housing 62 comprising openings for receiving the flux bridges 64 therein. The flux bridges 64 are then inserted into the openings of the housing 62 to complete the assembly.

Referring back to fig. 3 and 4, slot closure 60 may have a length that is substantially equal to the length of stator core 32, e.g., the distance between ends 36 and 38. Flux bridges 64 may be continuous along slot closure member 60 and, in addition, have a length substantially equal to the length of core 32. The slot closure 60 may be installed in the slot opening 50 by inserting the slot closure 60 into the opening 50 from one end of the core 32.

The teeth 33 and slot closure 60 may include features that cooperate to retain the slot closure 60 in the slot opening 50. For example, the teeth 33 may include recessed portions 102, the recessed portions 102 receiving the tabs 104 of the slot closure 60. A recessed portion 102 may be formed on each opposing side of the teeth 33 and each opposing side of the slot closure 60 may include a tab 104 to fully secure the slot closure 60 in place. The recessed portion 102 may extend along the length of the teeth 33 and the protrusion 104 may extend along the length of the slot closure 60.

The slot closure 60, which includes both electrical conduction (e.g., flux bridges 64) and insulation (e.g., housing 62 material), provides a high permeability path for the magnetization flux across the air gap 71 between the stator 22 and rotor 24 and provides improved characteristics at both high and low torque operating points. At high torque, the flux bridges 64 provide a path for extraneous leakage flux that may contribute to torque ripple, while at low torque, the nonmagnetic gaps prevent excess magnetization flux from being lost due to leakage. Previous metal wedge slot closures did not have any nonmagnetic gaps and could not prevent excessive magnetizing flux loss due to leakage during low torque operation.

The slot closures 60 may all be arranged in the slot openings 50 in the same orientation as shown in fig. 3. Alternatively, the slot closure 60 may be placed in different orientations in different slots 34. As shown in fig. 6, the direction of the slot closures 60 may alternate along the circumferential direction of the stator core 32. In fig. 6, adjacent slot closures are rotated 180 ° relative to each other about their longitudinal axes. This can be used to tune the torque ripple response, for example, by increasing the torque ripple to below the rated torque in exchange for reducing the torque ripple at the rated torque.

The flux bridges may be of many different sizes, shapes and orientations to meet the specific needs of a particular machine. Fig. 7 shows another slot closure member 120, the other slot closure member 120 including a single flux bridge 122 disposed in a housing 124. Similar to slot closure 60 described above, housing 124 encapsulates flux bridge 122 to form a non-magnetic gap between flux bridge 122, stator teeth 33, and windings 40. The flux bridges 122 may be cylindrical and have an elliptical cross-sectional shape with a major axis extending between the teeth and a minor axis extending in a radial direction of the stator core 32.

Referring to fig. 8, in yet another embodiment, the slot closure 130 includes three flux bridges 132, 134, and 136 disposed within the housing. Each of the flux bridges is completely surrounded by portions of the housing 138 to form a plurality of nonmagnetic gaps. A first portion of the housing 138 is disposed between the flux bridge 136 and the teeth 33 to form a first non-magnetic gap 139. The second portion of the housing 138 forms a non-magnetic gap 140 between the flux bridge 134 and the flux bridge 136. The third portion of the housing 138 forms a non-magnetic gap 142 between the flux bridge 132 and the flux bridge 136. The fourth portion of the housing 138 forms a nonmagnetic gap 144 between the flux bridge 132 and the flux bridge 134. The fifth portion of the housing 138 forms a non-magnetic gap 146 between the flux bridge 132 and the teeth 33.

The three flux bridges 132, 134, and 136 may be substantially identical, have different sizes and shapes, or a combination thereof. For example, the three flux bridges may be prismatic bodies having a rectangular cross-section, but wherein flux bridges 132 and 136 are larger than flux bridge 134. Of course, other combinations are possible, which allow the slot closures to be tuned to the particular motor to which they are mounted.

Referring to fig. 9, a method 150 of manufacturing a stator includes providing a stator core having slots with openings at step 152. The stator core may be the same as or similar to the stator core 32 described above. At step 154, conductors are installed in the slots to form stator windings. The windings may be distributed windings, concentrated windings, or hairpin windings. At step 156, the flux bridge is made of a ferromagnetic material. The flux bridges can be manufactured in a variety of different shapes and sizes as described above. At step 158, the flux bridges are encapsulated in a non-magnetic housing to form a plurality of slot closures. The non-magnetic housing may be formed by overmolding the flux bridges in an overmolding material, such as a plastic resin. According to an embodiment, a plurality of flux bridges may be arranged in a spaced apart relationship and encapsulated to form a slot closure having a plurality of flux bridges. At step 160, slot closures are inserted into the slot openings such that each non-magnetic housing forms at least one non-magnetic gap between a respective one of the flux bridges and the stator to reduce the likelihood of torque ripple.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously mentioned, the features of the various embodiments may be combined to form further embodiments of the invention, which may not be explicitly described or illustrated. While various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, and the like. Accordingly, embodiments described as less desirable with respect to one or more characteristics than other embodiments or prior art implementations are also within the scope of the present disclosure and may be desirable for particular applications.

According to an embodiment, the package further comprises overmolding the flux bridge in an overmolding material that hardens to form the housing.

According to an embodiment, the flux bridges have a length substantially equal to the length of the stator.