Rotary electric machine having a stator assembly with stator slots lined with a plurality of molding materials

Abstract

A stator assembly for an electric motor includes stator teeth connected to a stator yoke to form a stator core. Adjacent teeth define stator slots. Stator windings are disposed within said slots. A molding material fills the slots around the windings, providing desired thermoelectric performance levels, including electrical insulation, thermal conductivity, and / or electrostatic shielding levels, in different slot regions. One method insulates the stator assembly by inserting a molding tool into the slot to define a void volume, filling the void volume with a dielectric molding material, and curing the dielectric molding material to form a slot liner adjacent to the tooth walls. Slot openings between adjacent teeth are filled with a conductive resin to form an electrostatic shielding layer. The electrical system includes an AC voltage bus connected to a power inverter module and a motor having the aforementioned stator assembly.

Description

Background Technology

[0001] Electric traction motors and motor-generator units, commonly referred to in the art as rotating electrical machines, are used to perform work in various electromechanical systems. For example, high-voltage electric motors are commonly used in electrified vehicles and other electrified systems to generate torque, such as to power wheels, drive belts, or rotary joints, while high-voltage generators are used to generate electricity. Such motors include a rotating component / rotor spaced shortly from surrounding stationary components / stators. In the stator assembly, multiple stator teeth are attached to a cylindrical stator yoke. The stator teeth project radially toward the rotor, which is typically positioned along the centerline of the stator assembly.

[0002] Further concerning the stator assembly construction, adjacent stator teeth are separated from each other by corresponding stator slots. These stator slots are filled with conductive wires or solid strip conductors to form stator windings. In an exemplary multiphase / alternating current (AC) rotating motor, an AC input voltage is applied to the stator windings from a power inverter module. The interaction between the rotor's magnetic field and the rotating magnetic field of the excited stator windings ultimately generates a push-pull force within the rotor-stator air gap. The resulting rotation of the rotor about its axis of rotation is then utilized and directed to the connected load. Summary of the Invention

[0003] This disclosure relates to improved slot insulation techniques for constructing rotating electric machines, wherein the machine is exemplified herein as an electric propulsion motor. Continuous operation of motors of the aforementioned type results in a significant amount of heat. This heat is particularly prevalent during continuous operation of the motor at high rotational speeds and / or high output torque levels. The heat generated and retained within the stator assembly structure ultimately reduces the electrical insulation on the stator windings, ultimately impairing motor performance. While thermal management systems are commonly used to regulate motor temperature, such as through controlled circulation of appropriate heat transfer fluids through the motor, additional features as described herein can be incorporated into the slot construction of the stator assembly to further optimize electrical and thermal performance.

[0004] In a particular approach, the slot insulation method envisioned herein involves the targeted use of molding materials that collectively provide predetermined levels of thermal and / or electrical (“thermoelectric”) performance in different regions of the stator slot, including two or more of electrical insulation, thermal conductivity, or electrostatic shielding. For this purpose, the molding compounds used to construct the molding materials each have different material compositions. Different molding compounds can individually provide grounding wall insulation, improved slot region thermal conductivity, and optional rotor electrostatic shielding.

[0005] As detailed herein, aspects of the proposed solution can be selectively implemented on existing / previously manufactured electric motor hardware to increase the operating voltage of such motors. By way of example, and not limitation, representative embodiments of the motor include, for example, a nominal 400V propulsion motor for battery-electric, hybrid-electric, or other electrified motor vehicles, which, using the teachings of this target slot insulation, can be modified to operate at a nominal 800V level. Therefore, a propulsion motor rated for a first voltage can be modified to operate at a higher second voltage, as detailed herein, possibly including implementations where the second voltage is approximately twice the first voltage.

[0006] As understood in the art, stator winding insulation for conductors in electric motors (e.g., those of the type commonly used as electric propulsion motors for electrified vehicles and other mobile platforms) often relies on paper slot liners to provide grounded wall insulation in the electromagnetically active regions of the stator assembly. Alternatively, enamel can be applied directly to the stator windings, where dielectric insulators and varnishes are also included on the weld side of such stator windings. The varnish used within the stator slots typically contains small cavitation or voids, primarily for mechanical reasons, which can collectively contribute to partial discharge events at lower operating voltages.

[0007] The insulation solution of the present invention relies on established manufacturing processes to transfer molding compounds with fundamentally different material properties. In the various embodiments detailed below, the molding compound includes at least two of the following: (i) a first molding compound (“slot liner”) having high dielectric strength, wherein the slot liner provides the aforementioned grounding wall insulation properties; (ii) a second molding compound (“slot filler”) having high thermal conductivity, which fills the void volume region within the stator slots, thereby reducing thermal interface resistance and partial discharge; and (iii) a third molding compound (“electrostatic shielding layer”) having high conductivity, which electromagnetically shields the magnetic rotor from adjacent stator windings, thereby reducing parasitic voltages that can be induced within the rotor.

[0008] In a representative embodiment, a stator assembly is described herein having a stator core. The stator core has a cylindrical stator yoke connected to radially projecting stator teeth or integrally formed with the radially projecting stator teeth. The stator assembly also includes stator windings and various molding materials. In this embodiment, the stator yoke, and thus the stator assembly, defines a central opening and has a longitudinal central axis, an outer diameter surface, and an inner diameter surface. The stator teeth are connected to the stator yoke and project radially into a central bore, i.e., toward the central axis. The stator teeth collectively define stator slots extending radially from the inner diameter surface of the stator yoke toward the outer diameter surface. The stator windings are disposed within the stator slots together with the aforementioned molding materials. The molding materials are located within each respective stator slot, thereby substantially filling the various void volumes present around the stator windings within the stator slots.

[0009] The molding material includes a slot liner that is adjacent to and in contact with the tooth walls of adjacent stator teeth, wherein the slot liner is constructed of a dielectric molding compound. The slot filler layer, in turn, contacts and surrounds the stator windings. The slot filler layer may be constructed of a thermally conductive molding compound, and in some embodiments, the thermally conductive molding compound may be the same as or similar to the material of the dielectric molding compound of the slot liner.

[0010] The dielectric molding compound can be constructed from a thermosetting polymer material having a dielectric strength of at least about 20 kV / mm. In some configurations, the dielectric molding compound can have a thermal conductivity of less than about 10 W / mK, for example, 0.75 W / mK or greater. The trench filling layer can have a thermal conductivity of at least about 1 W / mK, while other possible values ​​and ranges of thermal conductivity are provided herein.

[0011] The thermally conductive molding compound of the groove filling layer may be a thermosetting polymer, which may itself contain thermally conductive fillers and have a thermal conductivity of at least about 1 W / mK or greater than about 5 W / mK in different possible embodiments.

[0012] In some configurations of the stator assembly, each pair of adjacent stator teeth is separated by an arcuate slot opening. In other configurations, the slot opening is closed; that is, the stator assembly is characterized by the absence of slot openings. In embodiments where open slot openings are present, the multilayer slot-filling material may include an electrostatic shielding layer. The electrostatic shielding layer is constructed of a paramagnetic or nonmagnetic material and is disposed within the slot opening.

[0013] One aspect of this disclosure includes a stator assembly having an electrically insulating paper liner positioned adjacent to stator teeth within a stator slot. In some configurations, non-conductive spacers, such as dielectric polymers shaped into particles, spheres, or balls, are disposed between the stator windings and the stator core (i.e., the stator yoke or stator teeth).

[0014] Coolant channels may optionally be located within stator slots, such as in multilayer molded material and / or stator windings. In such embodiments, the coolant channels are configured to connect to a coolant supply and deliver heat transfer fluid or coolant to the stator assembly.

[0015] This document also discloses a method for insulating a stator assembly of a rotating electrical machine. A representative embodiment of this method includes inserting a first molding tool into a stator slot of the stator core of the stator assembly to define a first void volume between the first molding tool and the tooth walls of an adjacent pair of stator teeth of the stator core, and filling the first void volume with a dielectric molding compound. The method further includes curing the dielectric molding compound to form a slot liner adjacent to the tooth walls, removing the first molding tool from the stator slot to form a second void volume within the stator slot, and inserting a conductive stator winding into the second void volume. This embodiment of the method further includes filling the second void volume with a thermally conductive molding compound and curing the thermally conductive molding compound to form a slot-filling layer surrounding the conductive stator winding.

[0016] Another aspect of this disclosure relates to an electrical system having a power inverter module connectable to a direct current (DC) voltage bus and operable to output an alternating current (AC) output voltage in response to a DC input voltage. The electrical system also includes an AC voltage bus connected to the power inverter module and a rotating electric motor connected to the AC voltage bus. The rotating electric motor has a stator assembly comprising: a stator yoke defining a central opening and having a longitudinal central axis, an outer diameter surface, and an inner diameter surface; and a plurality of stator teeth connected to the stator yoke to form a stator core.

[0017] The stator teeth project radially toward the longitudinal central axis into the central opening and collectively define the stator slots. The stator slots extend radially from the inner diameter surface of the stator yoke toward the outer diameter surface. The stator windings are disposed within the stator slots. A molding material is disposed within and substantially fills the stator slots around the stator windings, providing predetermined insulation properties in different regions of the stator slots. In this embodiment, the molding material provides two or more predetermined levels of electrical insulation, thermal conductivity, or electrostatic shielding.

[0018] The molding material includes a slot liner adjacent to and in contact with the stator wall of the stator teeth, wherein the slot liner is constructed of a dielectric molding compound having a dielectric strength of at least about 20 kV / mm, and a slot filler layer surrounding the stator windings. The slot filler layer is constructed of a thermally conductive molding compound having a thermal conductivity of at least about 1 W / mK.

[0019] The present invention also includes the following solutions:

[0020] Option 1. A stator assembly, comprising:

[0021] A stator yoke, the stator yoke defining a central opening and having a longitudinal central axis, an outer diameter surface, and an inner diameter surface;

[0022] A plurality of stator teeth are connected to the stator yoke to engage with the stator yoke to form a stator core. The stator teeth project radially toward the longitudinal central axis into the central opening and collectively define a plurality of stator slots, wherein the stator slots extend radially from the inner diameter surface of the stator core yoke toward the outer diameter surface of the stator core yoke.

[0023] A conductive stator winding disposed within the stator slot; and

[0024] A molding material disposed within and substantially filling the volume of the stator slot surrounding the stator winding, and providing predetermined thermoelectric performance levels in different regions of the stator slot, including two or more of electrical insulation levels, thermal conductivity levels, or electrostatic shielding levels.

[0025] Option 2. The stator assembly according to Option 1, wherein the molding material comprises a slot liner and a slot filler, the slot liner being adjacent to and in contact with the stator wall of the stator teeth and being constructed of a dielectric molding compound, and the slot filler surrounding the stator winding and being constructed of a thermally conductive molding compound.

[0026] Option 3. The stator assembly according to Option 2, wherein the dielectric molding compound of the slot liner is constructed of a first thermosetting polymer material having a dielectric strength of at least about 20 kV / mm, and the thermally conductive molding compound of the slot filling layer is constructed of a second thermosetting polymer material comprising thermally conductive particles and / or fiber filler material.

[0027] Option 4. The stator assembly according to Option 3, wherein the dielectric molding compound of the slot liner has a thermal conductivity of about 0.75 W / mK to about 10 W / mK, and the slot filling layer has a thermal conductivity of at least about 1 W / mK.

[0028] Option 5. The stator assembly according to Option 2, wherein each pair of adjacent stator teeth is separated by a corresponding slot opening, and the molding material includes an electrostatic shielding layer disposed within the corresponding slot opening and constructed of a conductive material.

[0029] Option 6. The stator assembly according to Option 2, wherein the stator assembly is characterized in that there is no stator slot opening between each pair of adjacent stator teeth, such that the stator slot is closed.

[0030] Option 7. The stator assembly according to Option 1, wherein the stator assembly includes an electrically insulating paper liner positioned adjacent to a stator tooth in each of the respective stator slots.

[0031] Option 8. The stator assembly according to Option 1 further includes a dielectric spacer disposed between the stator winding and the stator yoke.

[0032] Option 9. The stator assembly according to Option 1 further includes a coolant passage disposed in one or more of the stator slots, wherein the coolant passage is configured to be connected to a supply of heat transfer fluid.

[0033] Option 10. The stator assembly according to Option 1, wherein the molding material comprises a dielectric molding compound, a thermally conductive molding compound, and a conductive resin material, the dielectric molding compound being disposed between the tooth wall of an adjacent stator tooth and the thermally conductive molding compound, the thermally conductive molding compound being disposed between the dielectric molding compound and the stator winding, and the conductive resin material being disposed in a slot opening defined between adjacent stator tooth pairs.

[0034] Option 11. A method for insulating a stator assembly of a rotating electrical machine, comprising:

[0035] A first molding tool is inserted into a stator slot in the stator core of the stator assembly, thereby defining a first gap volume between the first molding tool and the tooth walls of an adjacent pair of stator teeth in the stator core.

[0036] The first void volume is filled with a dielectric molding compound;

[0037] The dielectric molding compound is cured to form a groove liner adjacent to the tooth wall;

[0038] Remove the first molding tool from the stator slot to form a second void volume within the stator slot;

[0039] The conductive stator winding is inserted into the second void volume;

[0040] The second void volume is filled with a thermally conductive molding compound; and

[0041] The thermally conductive molding compound is cured to form a slot-filling layer surrounding the conductive stator winding.

[0042] Option 12. The method according to Option 11 further includes:

[0043] The slot openings between adjacent pairs of stator teeth are filled with conductive resin; and

[0044] The conductive resin is cured to form an electrostatic shielding layer.

[0045] Option 13. The method according to Option 12 further includes:

[0046] Before filling the first void volume with the dielectric molding compound, a second molding tool is inserted into the slot opening; and

[0047] After the dielectric molding compound has cured and before the groove opening has been filled with the conductive resin, the second molding tool is removed from the groove opening.

[0048] Option 14. The method according to Option 11, wherein the dielectric molding compound comprises a thermosetting polymer material having a dielectric strength of at least about 20 kV / mm.

[0049] Option 15. The method according to Option 14, wherein the dielectric molding compound has a thermal conductivity of about 0.75 W / mK to about 10 W / mK.

[0050] Option 16. The method according to Option 11, wherein the thermally conductive molding compound comprises a thermosetting polymer material having a thermal conductivity of at least about 1 / mK and containing conductive particles and / or fiber fillers.

[0051] Option 17. The method according to Option 11 further includes forming at least one coolant passage in the stator slot, wherein the at least one coolant passage is configured to be connected to a supply of heat transfer fluid.

[0052] Option 18. An electrical system comprising:

[0053] A power inverter module that can be connected to a DC voltage bus and is operable to output an AC output voltage in response to a DC input voltage;

[0054] The AC voltage bus connected to the power inverter module; and

[0055] A rotary motor connected to the AC voltage bus, the rotary motor having a rotor assembly surrounded by a stator assembly, the stator assembly including:

[0056] A stator yoke, the stator yoke defining a central opening and having a longitudinal central axis, an outer diameter surface, and an inner diameter surface;

[0057] A plurality of stator teeth are connected to the stator yoke to form a stator core. The stator teeth project radially toward the longitudinal central axis into the central opening and collectively define a plurality of stator slots, wherein the stator slots extend radially from the inner diameter surface of the stator yoke toward the outer diameter surface.

[0058] A conductive stator winding disposed within the stator slot; and

[0059] A molding material disposed within and substantially filling the stator slots surrounding the stator winding, and providing predetermined thermoelectric performance levels at different regions of the stator slots, including two or more of electrical insulation, thermal conductivity, or electrostatic shielding levels, wherein the molding material comprises a slot liner and a slot filler layer, the slot liner being adjacent to and in contact with the stator wall of the stator teeth, the slot liner being constructed of a dielectric molding compound having a dielectric strength of at least about 20 kV / mm, and the slot filler layer surrounding the stator winding, wherein the slot filler layer is constructed of a thermally conductive molding compound having a thermal conductivity of at least about 1 W / mK.

[0060] Option 19. The electrical system according to Option 18, wherein each pair of adjacent stator teeth is separated by slot openings, and the molding material includes an electrostatic shielding layer disposed within the slot openings and constructed of a conductive material.

[0061] Option 20. The electrical system according to Option 18, wherein the electrical system is part of an electrified vehicle, and wherein the rotary motor is a propulsion motor for the electrified vehicle.

[0062] The foregoing summary is not intended to represent every possible embodiment or aspect of this disclosure. Rather, it is intended to illustrate some novel aspects and features disclosed herein. The foregoing features and advantages, as well as other features and advantages, will become apparent from the following detailed description of representative embodiments and modes for carrying out this disclosure, taken in conjunction with the accompanying drawings and appended claims. Attached Figure Description

[0063] Figure 1 This is a schematic illustration of an exemplary electrical system having a rotating motor with a stator assembly incorporating the molding material described herein.

[0064] Figure 2 It is a schematic plan view of a stator assembly, depicting a stator yoke and stator teeth, wherein stator slots located between adjacent stator teeth are filled with the molding material of this disclosure.

[0065] Figure 3 yes Figure 2 A cross-sectional view of a portion of the stator assembly, depicting a representative stator slot lined with and filled with molding material.

[0066] Figure 4 This is a cross-sectional view of a conductor of a representative stator winding, wherein the conductor is equipped with non-conductive spacer particles according to aspects of this disclosure.

[0067] Figure 5A method for constructing stator assemblies using the molding material described herein is described.

[0068] This disclosure allows for modifications and alternatives, with representative embodiments illustrated by way of example in the accompanying drawings and described in detail below. The inventive aspects of this disclosure are not limited to the disclosed embodiments. Rather, this disclosure is intended to cover modifications, equivalents, combinations, and alternatives that fall within the scope of this disclosure as defined by the appended claims. Detailed Implementation

[0069] This disclosure allows for embodiments in many different forms. Representative examples of this disclosure are shown in the accompanying drawings and are described in detail herein as non-limiting examples of the disclosed principles. Therefore, elements and limitations described in the abstract, introduction, summary, and detailed description sections but not expressly set forth in the claims should not be incorporated into the claims, individually or collectively, by implication, inference, or otherwise.

[0070] For the purposes of this specification, unless specifically waived, the use of the singular includes the plural and vice versa; the terms “and” and “or” should be both connective and disjoint; “any” and “all” should both mean “any and all”; and the words “including,” “containing,” “comprising,” “having,” etc., should mean “including rather than limiting.” Furthermore, approximate words such as “about,” “almost,” “substantially,” “generally,” “approximately,” etc., may be used herein in the sense of “being, near, or almost being” or “within ±5%” or “within acceptable manufacturing tolerances” or logical combinations thereof.

[0071] Referring to the accompanying drawings, in which the same reference numerals in several drawings denote the same or similar parts, electrical system 10 in Figure 1 The diagram is schematically depicted. The electrical system 10 includes a rotating electric motor 12 having a rotor assembly (“R”) 14 and a stator assembly (“S”) 16, the stator assembly 16 being equipped with the following detailed reference. Figure 3 The molding material 40 is described in detail. In this embodiment, the corresponding rotor and stator assemblies 14 and 16 are separated by a radial air gap 17.

[0072] The improvements described below pertain to the construction of stator assembly 16, and therefore rotor assembly 14 will not be described in detail. However, those skilled in the art will understand that rotor assembly 14 may optionally be implemented as an iron-containing / magnetic column with a set of permanent magnets attached to or embedded within it, wherein each permanent magnet is composed of, for example, ferrite, neodymium iron boron (“NdFeB”), samarium cobalt (“SmCo”), or another suitable magnetic material. In other configurations, rotor assembly 14 may operate as a reluctance rotor, and therefore the use of such permanent magnets is not necessary within the scope of this disclosure. That is, the construction of rotor assembly 14 can vary depending on the specific application, and therefore... Figure 1 The description in the text represents only one possible construction.

[0073] As described herein, stator assembly 16 is equipped with... Figure 2 and Figure 3 The molding material is generally shown as 40. As understood in the art, stator assembly 16 can sometimes generate significant heat, such as during sustained high-power / high-torque operating modes of rotating motor 12. This teaching aims to reduce operating temperature, improve operation, and extend the life of stator assembly 16, wherein some embodiments described below also enable improvements to existing rotating motor 12 using this teaching, such as increasing the excitation voltage from a nominal 400V level to a nominal 800V level, for example, as described above.

[0074] In a typical embodiment of the electrical system 10, a suitable heat transfer fluid 21, such as automatic transmission fluid, a diluted glycol mixture, or other suitable coolant, may be stored in a reservoir 22 and circulated through the rotary motor 12, for example, by operation of a coolant pump (“P”) 23. The resulting flow of the heat transfer fluid 21 in… Figure 1 The symbol FF is schematically indicated in the diagram, where the following description and... Figure 3 The embodiment shown may guide the heat transfer fluid 21 through the multiple stator slots 20 of the stator assembly 16 for this purpose (see [link]). Figure 2 ).

[0075] exist Figure 1 In the exemplary electrical system 10 shown, the rotor assembly 14 is concentrically arranged within the stator assembly 16, i.e., the stator assembly 16 is externally connected to and thus surrounds the rotor assembly 14, as shown. The rotating motor 12 will therefore be a radial flux type motor, and in this particular embodiment, the aforementioned air gap 17 will be a radial stator-rotor air gap. Other possible configurations of the rotating motor 12 can be implemented, wherein the relative positions of the rotor assembly 14 and the stator assembly 16 are reversed, such that the rotor assembly 14 is externally connected to and surrounds the stator assembly 16. For consistency of illustration, the following will describe... Figure 1A representative embodiment is provided in which the rotor assembly 14 is radially located within the stator assembly 16, without limiting the construction to this configuration.

[0076] Figure 1 The electrical system 10 is shown in possible configurations as a representative propulsion system, such as for an electrified motor vehicle, robot, or other mobile platform (not shown). In this embodiment, the electrical system 10 includes an AC (“AC”) voltage bus 13 selectively energized via a traction power inverter module (“TPIM”) 28. This is transmitted through a high-voltage battery pack (“B”). HV This occurs during the operation of 24 (e.g., multi-unit lithium-ion, lithium-sulfur, nickel metal hydride, or another suitable high-energy voltage source). The AC voltage bus 13 transmits AC voltage (“VAC”) to / from the individual phase windings of the rotating motor 12 as needed to generate output torque (arrow T). M When operating in drive mode or electric mode, the output torque from the energized rotary motor 12 (arrow T) M Ultimately, it is applied to the connected rotor shaft 51 and directed to the coupled load (“L”) 54, such as by one or more wheels of the exemplary electrified vehicle described above, or alternatively, a propeller shaft, drive belt, rotary joint, or other component of a fixed or moving system.

[0077] Still referencing Figure 1 The electrical system 10 may also include a DC voltage bus 15 connected to a DC-DC (“DC-DC”) converter 26, such as an auxiliary power module. As will be understood by those skilled in the art, the DC-DC converter 26 is configured to decrease or increase a relatively high DC voltage (“VDC”) as needed via switching and filtering operations based on internal semiconductors. The DC-DC converter 26 is connected between the battery pack 24 and the TPIM 28 via the positive (+) and negative (-) rails or terminals on the high-voltage side of the DC voltage bus 15. In some configurations, the low-voltage / auxiliary battery pack (“B…”) is connected between the battery pack 24 and the TPIM 28. AUX The auxiliary battery pack 124 can be connected to the positive (+) and negative (-) rails or terminals on the low-voltage side of the DC voltage bus 15, wherein the auxiliary battery pack 124 may be implemented as a lead-acid battery or a battery constructed of another suitable chemical composition for the application, and is configured to store or supply an auxiliary voltage of 12-15V (“V”). AUX () to one or more connected auxiliary devices (not shown).

[0078] Now for reference Figure 2 As will be understood by those skilled in the art, the above references Figure 1The stator assembly 16 of the exemplary rotary motor 12 described may be constructed from a stack of annular, thin laminations (“lam”) of electrical steel or another ferrous material, for example, 2-5 mm thick per lamin. The stator assembly 16 also has a plurality of stator teeth 16T, each stator tooth projecting radially from a cylindrical stator yoke 16Y having an outer diameter (OD). Furthermore, the stator yoke 16Y, and therefore the stator assembly 16, has an outer diameter surface 260 and an inner diameter surface 360, and surrounds a central opening 160 defined by the stator yoke 16Y. The stator teeth 16T extend radially inward toward the longitudinal central axis 11 of the stator assembly 16, wherein… Figure 1 The longitudinal central axis 11 in the configuration shown also serves as the axis of rotation for the rotor shaft 51. The stator yoke 16Y and stator teeth 16T thus form the stator core 16C.

[0079] like Figure 2 As shown, each pair of adjacent stator teeth 16T is separated by a corresponding stator slot 20. That is, each stator slot 20 is defined by a pair of adjacent stator teeth 16T and has said pair of adjacent stator teeth 16T on both sides. The conductive stator winding 30 is positioned within the stator slot 20. For simplicity and clarity, Figure 2 Details have been omitted. See below for reference. Figure 3 Exemplary embodiments of the stator winding 30 are described, wherein the stator winding 30 in various embodiments takes the form of conductive wires or rod segments, typically, but not necessarily, made of copper. Each stator winding 30 is ultimately connected to... Figure 1 The AC voltage bus 13 is electrically excited by it. Within the scope of this disclosure, each of the stator slots 20 is lined and / or filled with a multilayer molding material 40, which will now be referenced. Figures 3-5 Describe its structure in detail.

[0080] Figure 3 A representative stator slot 20 constructed according to this teaching is shown. In particular, a variety of different polymeric molding compounds are used in the construction of the multilayer molding material 40 to optimize performance, especially in terms of improved grounding wall insulation and thermal conductivity in specific regions of the stator slot 20, and also... Figure 1 The increased electrostatic shielding near the air gap 17. As depicted, the stator slot 20 has a width (W) and a length (L). The length (L) extends from a first end E1 of the stator slot 20 near the outer diameter surface 260 of the stator yoke 16Y to a second end E2 adjacent to and possibly adjacent to or leading to the inner diameter end 360. Therefore, the volume defined by the stator slot 20 is determined by the width (W), length (L), and depth of the slot 20, i.e. Figure 1 and Figure 2The axial length of the stator assembly 16 is defined, as will be understood by those skilled in the art. This slot volume is primarily, but not entirely, occupied by the stator winding 30, while the remaining slot volume is substantially occupied by the molding material 40 of this disclosure.

[0081] As envisioned herein, the molding material 40 provides different predetermined levels of electrical insulation and thermal conductivity within each stator slot 20. For this purpose, each corresponding molding compound used in the construction of the molding material 40 is injected or otherwise applied to a specific corresponding region of the stator slot 20 to optimize thermal and electrical properties in a region-specific manner within each stator slot 20.

[0082] In one possible embodiment, molding material 40 forms a groove liner 42, which is positioned adjacent to and in contact with the stator tooth 16T, i.e., coating or lining its groove tooth wall 200. Figure 1 and Figure 2 In a possible configuration of the stator assembly 16, the molding material 40 suitable for constructing the slot liner 42 comprises a dielectric molding compound in an uncured and moldable state prior to molding with the stator assembly 16. In possible embodiments, the slot liner 42 may be constructed from a thermosetting polymer material having a dielectric strength of at least about 20 kV / mm. In some configurations, the molding material 40 of the slot liner 42 may have a thermal conductivity of less than about 10 W / mK. Exemplary molding materials include, but are not limited to, epoxy resins, phenolic resins, polyurethanes, silicones, acrylic resins, polyesters, bismaleimides, benzoxazines, etc. Although not strictly necessary, such molding materials may optionally be filled with solid particulate materials or short fibers, such as glass fibers, silica, oxides, nitrides, or other suitable structural reinforcements of aluminum, silicon, etc.

[0083] Figure 3 The slot filler layer 44 shown is disposed between the stator winding 30 and the aforementioned slot liner 42, wherein the slot filler layer 44 surrounds the stator winding 30. For clarity, in Figure 3 A small air gap 31, enlarged in size, can exist between the stator winding 30 and the adjacent slot fill layer 44, for example, due to processing ( Figure 5 And in order to have sufficient space for mounting the stator winding 30, the slot filler layer 44 envisioned herein is constructed of a thermally conductive molding compound, such as a thermosetting polymer containing thermally conductive particulate filler and having a thermal conductivity of at least about 1 W / mK or greater than about 5 W / mK in other configurations.

[0084] The molding material 40 used to construct the groove filling layer 44 can be of roughly the same category as the molding material 40 used to construct the groove liner 42. However, the particulate filler of the polymeric molding compound used for the groove filling layer 44 is specifically conductive, i.e., non-dielectric. Therefore, suitable conductive materials include aluminum, copper, nickel, tin, iron, silver, gold, and various alloys. Other suitable materials include carbon-based materials such as carbon black, nanotubes, graphene, diamond, etc.

[0085] To reduce costs and simplify manufacturing, the same materials can be used to construct the slot liner 42 and the slot filler layer 44. In this embodiment, the molding materials for the slot liner 42 and the slot filler layer 44 can be added to the stator slot 20 in the same manufacturing step, thereby simplifying and streamlining the manufacturing process. Even if the same or similar polymers are used everywhere, molding will be performed in two steps: (1) a first molding process occurs before the insertion of the stator winding 30 to form the slot liner 42, and (2) a second molding process occurs after the insertion of the stator winding 30, as referenced below. Figure 5 What is described.

[0086] In some embodiments, each pair of adjacent stator teeth 16T is separated by an arcuate slot opening 45 along the inner diameter surface 360, wherein the slot opening 45 is also as... Figure 2 As depicted. When the slot opening 45 is open, the multilayer molding material 40 may include an electrostatic shielding layer 46 disposed within the slot opening 45. For each molding, the electrostatic shielding layer 46 may be constructed of austenitic or conductive paramagnetic material, such as a conductive polymer.

[0087] In the initial configuration with slot opening 45, the hardened / cured electrostatic shielding layer 46 effectively acts as a Faraday shield, thus closing the slot opening 45 with the electrostatic shielding layer 46 helps reduce parasitic losses. Without the electrostatic shielding layer 46, that is, since the laminations of the stator assembly 16 are ferromagnetic, there would be a possibility of reduced... Figure 1 The magnetic flux leakage path of the rotor assembly 14. Optionally, the multilayer molding material 40 may include a paper liner 49 positioned near the tooth wall 200 of the stator teeth 16T within the stator slot 20 and serving as an electrical insulator, having for use with reference below. Figure 5 The described embodiment with this insulating paper 49 is selected to work together.

[0088] Still referencing Figure 3 Within the scope of this disclosure, various embodiments comprising two or more of the aforementioned layers are conceivable, namely, slot liner 42, slot filler 44, or electrostatic shielding layer 46. In one such embodiment, the stator slot 20 can be as follows: Figure 3 It is molded as depicted in the description, namely, the groove liner 42, the groove filler 44, and the electrostatic shielding layer 46.

[0089] Alternatively, each stator slot 20 can be lined with a paper liner 49, or the stator assembly 16 that already has such a paper liner 49 can be improved. In either case, the stator slot 20 can be molded using a slot filling layer 44 and an electrostatic shielding layer 46. Thus, this embodiment will include two layers, namely the slot filling layer 44 and the electrostatic shielding layer 46, as well as the aforementioned paper liner 49, which can actually be considered as an additional layer of multilayer molding material 40.

[0090] In yet another embodiment, Figure 1 and Figure 2 The stator assembly 16 may be characterized by the absence of the arcuate slot opening 45. That is, the adjacent tips of the individual stator teeth 16T may abut or engage with each other, or be integrally formed, such that the stator slot 20 is closed at both ends E1 and E2. Such an embodiment can utilize the slot liner 42 and the slot filler layer 44, foregoing the use of the electrostatic shielding layer 46, for a total of two layers.

[0091] Those skilled in the art will understand from this disclosure that embodiments of the teachings may include providing a reference stator assembly 16 having the aforementioned insulating paper liner 49 mounted in the stator slot 20. In a representative embodiment, Figure 1 The rotary motor 12 can be configured, for example, as an electric propulsion motor for electrified motor vehicles, ships, aircraft, rail vehicles, robots, power units, or other moving or stationary platforms. When the rotary motor 12 is initially configured to operate at a first output voltage, for example, 400-500V in a representative first voltage example, the addition of the slot-filling layer 44 and the electrostatic shielding layer 46 can be used to improve the initial insulation capability of the rotary motor 12. This helps to make Figure 1 The rotary motor 12 is capable of operating at higher output voltages, such as nominal 800-1000V, consistent with the non-limiting 400-500V example.

[0092] Another conceivable embodiment is that the coolant passage 52 is disposed within the stator slot 20, for example, in the conductor forming the stator winding 30, or in the surrounding material 40, such as in Figure 3 and Figure 5 The coolant channel 52 is located in the filler layer 44 shown in the diagram. This coolant channel 52 is configured to connect to a coolant supply, for example... Figure 1 The reservoir 22 and pump 23. For example, the stator winding 30 may be configured as a hollow conductor, such that the coolant channel 52 is defined by copper or other conductive material. Other methods may include molding the coolant channel 52 into various molding compounds used to construct the slot liner 42 and / or slot filler layer 44, i.e., molding the slot will allow the cooling channel 52 to be formed within the molding compound, as an alternative to more complex methods such as using hollow conductors.

[0093] Various methods can be used for this purpose, such as molding a dummy insert inside the stator slot 20, wherein such insert defines the shape and geometry of the coolant channel 52. As those skilled in the art will understand, such coolant channel 52 is retained when the dummy insert is subsequently removed.

[0094] Brief Reference Figure 4 49, replacing paper lining Figure 1 and Figure 2 The stator assembly 16 may include stator windings 30 and stator yoke 16Y and / or stator teeth 16T (see...). Figure 3 Electrically insulating (or thermally conductive) spacers 50 are provided between the stator windings 30 and the spacers 50. Spacers 50 may be constructed from resin comprising suspended particles, spheres, or balls containing dielectric / insulating material. Alternatively, a solid material with an adhesive coating may be applied to the outer surface 300 of the stator windings 30, or applied to... Figure 3 On the slotted wall 200, to ensure the spacing between the stator winding 30 and the slotted wall 200, and to eliminate the need for the paper liner 49 or the first molding step. The maximum size of this spacer 50 should be smaller than that of the stator winding 30 and the slotted wall 200. Figure 3 The intended spacing of the slotted tooth walls 200 is such that there is sufficient clearance during the insertion of the stator winding 30, but large enough to ensure that... Figure 2 The minimum required spacing is maintained between the stator winding 30 and the stator core 16C.

[0095] In some embodiments, for constructing Figure 4 The molding material for spacer 50 can be the same dielectric molding material used to construct slot liner 42. If a solid material is used to construct spacer 50, an electrically insulating / dielectric material such as ceramic, glass, or a suitable polymer can be used. As a few examples, exemplary materials for this purpose include oxides, nitrides, epoxy resins, phenolic resins, or thermoplastic polymers. Solid materials may require adhesives to adhere to stator winding 30, such as epoxy resins, phenolic resins, acrylates, polyurethanes, or another polymer with a suitable adhesive. In the case of thermoplastics or partially cured thermosetting plastics, the molding material can be molten / liquid-sprayed onto stator winding 30 such that the molding material adheres appropriately to stator winding 30 after subsequent cooling.

[0096] refer to Figure 5 This shows the use of Figure 3 Molded material 40 construction Figure 1 and Figure 2Method 100 for stator assembly 16. As generally described above, up to three different molding compounds can be used, and therefore the described embodiments are adaptable for constructing various alternative configurations described above. Method 100 is described with respect to operation on one stator slot 20, and as shown, its description applies to multiple stator slots 20, that is, the manner in which a given stator slot 20 is molded is applicable. Figure 2 Each remaining stator slot 20, and in most practical implementations, is carried out simultaneously.

[0097] Beginning with box B102, where a “box” represents one or more specific steps in the process sequence for implementing method 100, the assembled stator core 16C (see [link to documentation]). Figure 2 The stator slots 20 can be arranged on the working surface, wherein the stator slots 20 are defined by two adjacent stator teeth 16T. Once arranged in this way, method 100 proceeds to block B104, as indicated by arrow A, possibly with the aid of a fixing device or support.

[0098] At box B104, a first molding tool T1 and a second molding tool T2 can be inserted into the stator slot 20. The corresponding first and second molding tools T1 and T2 can be removable physical barriers that, together with the slot wall 200, define the volume and geometry of the first void volume V1. Method 100 then proceeds to box B106, as indicated by arrow B.

[0099] In block B106, the first void volume V1 needs to be filled with the dielectric molding compound of the groove liner 42, and then the molding compound is allowed to cure. In various embodiments, molding and subsequent steps may include, for example, transfer molding, injection molding, casting, vacuum casting, etc. As understood in the art, the resin may be injected as a liquid into the corresponding first void volume V1 and then hardened. Curing may continue until the groove liner 42 has been sufficiently cured for the purpose of removing the second molding tool T2. Method 100 then proceeds to block B108, as indicated by arrow C.

[0100] In box B108, the second molding tool T2 is removed, leaving the slot opening 45. The slot 20 is lined with a slot liner 42 at this stage, with the first molding tool T1 still in place. Method 100 then proceeds to box B110, as indicated by arrow D.

[0101] Still referencing Figure 5 Block B110 includes filling the groove opening 45 with the conductive material described above as serving as the electrostatic shielding layer 46, and subsequently allowing the injected material to cure. Method 100 then proceeds to block B112.

[0102] Box B112 requires the removal of the first molding tool T1. This action leaves a large void volume V2 in the stator slot 20, which is surrounded by the slot liner 42 and the electrostatic shielding layer 46. Method 100 then proceeds to box B114.

[0103] exist Figure 5 In frame B114, the conductors of stator winding 30 are spaced apart within the second gap volume V2 of frame B112. Although in Figure 5 Four conductors are shown at box B114, but fewer or more conductors may be present in other embodiments. The insertion of the conductors leaves a third void volume V3 around the conductors, i.e., empty space around the conductors. Once the conductors of the stator winding 30 have been inserted into the stator slots 20, method 100 proceeds to box B116, as shown.

[0104] Block B116 includes filling the third void volume V3 with the aforementioned thermally conductive compound to form a slot-filled layer 44. Alternatively, in addition to or instead of using potentially expensive hollow conductors for the stator winding 30, coolant channels 52 can be simultaneously molded within the slot-filled layer 44, for example, using a removable tool (not shown).

[0105] In a more general embodiment, the method for insulating the stator assembly 16 of the rotating electric motor 12 may include inserting a molding tool into a stator slot 20 of the stator core 16C of the stator assembly 16, thereby defining at least one void volume within the stator slot 20, for example, in the molding tool, for example... Figure 5 The first void volume V1, as described above, is formed between the second molding tool T2 and the slot wall 200 of an adjacent pair of stator teeth 16T of the stator core 16C. The void volume is filled with a dielectric molding compound, which is then cured to form a slot liner 42 adjacent to the tooth wall 200. The molding tool is then removed from the stator slot 20. This method continues by filling the voids in the slot openings 45 between adjacent pairs of stator teeth 16T with conductive resin to form… Figure 3 46. ​​Electrostatic shielding layer.

[0106] In some embodiments, such as the improved 400V to 800V example mentioned above, the stator slot 20 is occupied by the conductive stator winding 30 before insertion of the molding tool and before injection of the described dielectric material. In some cases, the stator winding 30 may be wound in a paper liner 49, also before insertion of such a molding tool. Implementations may include... Figure 4 The dielectric spacer 50 is positioned between the stator winding 30 and the stator yoke 16Y.

[0107] In the manufacturing process of a void volume comprising a first void volume V1 adjacent to the slot tooth wall 200 and a second void volume V2 adjacent to the first void volume V1, the method may include filling the second void volume V2 with a previously described thermally conductive molding material, wherein the second void volume V2 is adjacent to the slot liner 42. This is followed by curing the thermally conductive molding material to form a slot filling layer 44, and then removing the molding tool, in this case, the molding tool T2, from the stator slot 20. Various possible implementations of the method may include forming within the stator slot 20... Figure 3 The coolant passage 52, wherein the coolant passage 52 is configured to connect to Figure 1 The supply of the heat transfer fluid 21 shown.

[0108] This teaching aims to provide a slot insulation system and accompanying method for filling the stator slots 20 of the stator assembly 16 described above with various molding compounds of the multilayer molding material 40 described above. In general, the multilayer molding material 40 reduces transmission line phenomena known as the corona effect, where a localized electric field near the stator slot 20 can cause ionization and thus partial discharge. The layered approach to molding the stator slot 20 provides an application-appropriate level of grounding wall insulation, improved thermal conductivity in the design area of ​​the stator slot 20, and surrounding ferrous material of the stator core 16C, and in some configurations, provides electrostatic shielding near the air gap 17 between the stator assembly 16 and the rotor assembly 14, such as... Figure 1 What is depicted.

[0109] Various aspects of the present invention can be selectively implemented on existing motor hardware to increase the excitation voltage as described above without insulation failure and without requiring excessive design of the insulation system of the stator assembly 16. Thus Figure 1 The final construction of the rotating electric motor 12, or a similar configuration thereof, enjoys reduced operating temperature and rotor parasitic voltage. Furthermore, the disclosed method 100 can help reduce the complexity of the HV insulation system for upgrading the rotating electric motor 12, thereby reducing manufacturing costs and potentially avoiding maintenance costs associated with premature insulation failure. In view of the foregoing disclosure, those skilled in the art will readily understand these and other accompanying benefits of this teaching.

[0110] While some preferred modes and other embodiments have been described in detail, various alternative designs and embodiments exist for implementing the teachings as defined in the appended claims. Those skilled in the art will recognize that modifications can be made to the disclosed embodiments without departing from the scope of this disclosure. Furthermore, the concept explicitly includes combinations and sub-combinations of the described elements and features. The detailed description and accompanying drawings are supportive and descriptive of the teachings, the scope of which is defined only by the claims.

Claims

1. A stator assembly comprising: a stator yoke defining a central opening and having a longitudinal center axis, an outer diameter surface, and an inner diameter surface; a plurality of stator teeth connected to the stator yoke to combine with the stator yoke to form a stator core, the stator teeth projecting radially into the central opening toward the longitudinal center axis and collectively defining a plurality of stator slots, wherein the stator slots extend radially from the inner diameter surface of the stator yoke toward the outer diameter surface of the stator yoke; an electrically conductive stator winding disposed within the stator slots; a dielectric spacer disposed between the stator winding and the stator yoke, wherein the dielectric spacer comprises a suspension of particles, spheres, or balls of a dielectric material; and a molding material disposed within and filling a volume of the stator slots surrounding the stator winding and providing a predetermined level of thermoelectric properties in different regions of the stator slots, including two or more of an electrical insulation level, a thermal conductivity level, or an electrostatic shielding level.

2. The stator assembly of claim 1, wherein the molding material comprises a slot lining layer adjacent to and in contact with stator walls of the stator teeth and constructed of a dielectric molding compound, and a slot fill layer surrounding the stator winding and constructed of a thermally conductive molding compound.

3. The stator assembly of claim 2, wherein the dielectric molding compound of the slot lining layer is constructed of a first thermoset polymer material having a dielectric strength of at least 20 kV / mm, and the thermally conductive molding compound of the slot fill layer is constructed of a second thermoset polymer material including thermally conductive particulate and / or fibrous filler material.

4. The stator assembly of claim 3, wherein the dielectric molding compound of the slot lining layer has a thermal conductivity of 0.75 W / mK to 10 W / mK, and the slot fill layer has a thermal conductivity of at least 1 W / mK.

5. The stator assembly of claim 2, wherein each pair of adjacent stator teeth is separated by a respective slot opening, and the molding material includes an electrostatic shielding layer disposed within the respective slot opening and constructed of an electrically conductive material.

6. The stator assembly of claim 2, wherein the stator assembly is characterized by an absence of a stator slot opening between each pair of adjacent stator teeth, such that the stator slots are closed.

7. The stator assembly of claim 1, wherein the stator assembly includes an electrical insulation paper liner positioned adjacent to the stator teeth of each respective one of the stator slots.

8. The stator assembly of claim 1, further comprising a coolant channel disposed within one or more of the stator slots, wherein the coolant channel is configured to be connected to a supply of a heat transfer fluid.

9. The stator assembly of claim 1, wherein the molding material comprises a dielectric molding compound, a thermally conductive molding compound, and an electrically conductive resin material, the dielectric molding compound is disposed between tooth walls of adjacent stator teeth and the thermally conductive molding compound, the thermally conductive molding compound is disposed between the dielectric molding compound and the stator winding, and the electrically conductive resin material is disposed in a slot opening defined between an adjacent pair of stator teeth.

10. A method for insulating a stator assembly of a rotating electric machine, comprising: inserting a first molding tool into a stator slot of a stator core of the stator assembly, thereby defining a first void volume between the first molding tool and tooth walls of an adjacent pair of stator teeth of the stator core; filling the first void volume with a dielectric molding compound; curing the dielectric molding compound to form a slot lining proximate the tooth walls; removing the first molding tool from the stator slot to form a second void volume within the stator slot; inserting an electrically conductive stator winding into the second void volume; filling the second void volume with a thermally conductive molding compound; and curing the thermally conductive molding compound to form a slot fill layer surrounding the electrically conductive stator winding.

11. The method of claim 10, further comprising: filling a slot opening between the adjacent pair of stator teeth with an electrically conductive resin; and curing the electrically conductive resin to form an electrostatic shield layer.

12. The method of claim 11, further comprising: prior to filling the first void volume with the dielectric molding compound, inserting a second molding tool into the slot opening; and after curing the dielectric molding compound and prior to filling the slot opening with the electrically conductive resin, removing the second molding tool from the slot opening.

13. The method of claim 10, wherein the dielectric molding compound comprises a thermoset polymer material having a dielectric strength of at least 20 kV / mm.

14. The method of claim 13, wherein the dielectric molding compound has a thermal conductivity of 0.75 W / mK to 10 W / mK.

15. The method of claim 10, wherein the thermally conductive molding compound comprises a thermoset polymer material having a thermal conductivity of at least 1 / mK and including electrically conductive particulate and / or fibrous filler material.

16. The method of claim 10, further comprising forming at least one coolant channel within the stator slot, wherein the at least one coolant channel is configured to be connected to a supply of heat transfer fluid.

17. An electrical system, comprising: a power inverter module connectable to a direct current voltage bus and operable to output an alternating current output voltage in response to a direct current input voltage; an alternating current voltage bus connected to the power inverter module; and a rotating electric machine connected to the alternating current voltage bus, the rotating electric machine having a rotor assembly surrounded by a stator assembly, the stator assembly comprising: a stator yoke defining a central opening and having a longitudinal center axis, an outer diameter surface, and an inner diameter surface; ​ ​ ​ ​ a plurality of stator teeth connected to the stator yoke to form a stator core, the stator teeth projecting radially into the central opening toward the longitudinal center axis and collectively defining a plurality of stator slots, wherein the stator slots extend radially from the inner diameter surface of the stator yoke toward the outer diameter surface; an electrically conductive stator winding disposed within the stator slots; and a molding material disposed within and filling the stator slots around the stator winding and providing a predetermined level of thermoelectric properties at different regions of the stator slots, including two or more of an electrical insulation level, a thermal conductivity level, or an electrostatic shielding level, wherein the molding material includes a slot lining layer adjacent to and in contact with stator walls of the stator teeth, the slot lining layer constructed from a dielectric molding compound having a dielectric strength of at least 20 kV / mm, and a slot filling layer around the stator winding, wherein the slot filling layer is constructed from a thermally conductive molding compound having a thermal conductivity of at least 1 W / mK.

18. The electrical system of claim 17, wherein, each pair of adjacent stator teeth is separated by a slot opening, and the molding material includes an electrostatic shielding layer disposed within the slot opening and constructed from an electrically conductive material.

19. The electrical system of claim 17, wherein the electrical system is part of an electrified vehicle, and wherein the rotating electric machine is a propulsion motor for the electrified vehicle.

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