THERMAL MANAGEMENT OF AN ELECTRIC MOTOR

Abstract

A motor includes a housing. The motor includes a stator with a plurality of slots arranged axially along the axis of rotation of a rotor, the stator having a first end and a second end, the first and second ends being separated along the axis of rotation of the rotor. The motor includes stator windings arranged on the plurality of slots, the stator windings comprising a main set of windings, a first set of end turns near the first end, and a second set of end turns near the second end. The motor includes a cooling sleeve surrounding the stator windings, the cooling sleeve having a first opening near the first end of the stator and a second opening near the second end of the stator, and a thermally conductive dissipation cap connected to the cooling sleeve.Abbreviated figure: Fig 1.

Description

Title of the invention: THERMAL MANAGEMENT OF AN ELECTRIC MOTOR technical field

[0001] This disclosure generally relates to electric motors adapted for aerospace applications. More specifically, this disclosure relates to a thermal management device for an electric motor and methods for implementing such thermal management.

[0002] CONTEXT

[0003] High-speed AC electric motors (for example, motors with operating speeds on the order of approximately 80,000 revolutions per minute) are required for many aerospace applications. To achieve such high rotational speeds, stator winding structures with a low pole count (for example, two or four poles) are used. However, the implementation of stator windings with a low pole count can result in windings with end turns exhibiting comparatively large bundled wire volumes (compared to slower motors or motors with more poles).Generally, these high-speed engines employ two air-cooling methods: one used during flight, in which fast-moving dynamic air from outside the aircraft is directed to the engine stator; and a second used when the aircraft is stationary on the ground, in which compressed air is directed to the engine stator. Tests and experience have shown that the aforementioned cooling methods do not uniformly cool the engines, resulting in detrimental asymmetric heat buildup, particularly in the bundled wires that make up the end turns of low-pole-count engines. Such detrimental heat buildup can degrade the insulation of the windings inside and around the end turns, thereby reducing engine life and increasing the risk of engine burnout.Therefore, achieving uniform heat dissipation in all regions of high-speed AC electric motors remains a source of technical challenges and opportunities for improvement in the field.

[0004] SUMMARY

[0005] This disclosure relates to the thermal management of an electric motor.

[0006] In some examples, a motor includes a housing. The motor includes a stator with a plurality of slots arranged axially along a rotational axis of a rotor, the stator having a first end and a second end, the first The motor has stator windings arranged in a plurality of slots. The stator windings comprise a main set of windings, a first set of end turns near the first end, and a second set of end turns near the second end. The motor includes a cooling sleeve surrounding the stator windings. The cooling sleeve has a first opening near the first end of the stator and a second opening near the second end of the stator. A thermally conductive heat dissipation cap is connected to the cooling sleeve.

[0007] In various embodiments, an apparatus includes a cooling sleeve, comprising a section of a thermally conductive material having a first opening proportioned to accommodate a first end of a stator, and a second opening proportioned to accommodate a second end of the stator and a thermally conductive dissipation cap thermally connected to the cooling sleeve.

[0008] In some embodiments, a method for thermal management of an electric motor comprises providing a housing, providing a stator with a plurality of slots arranged axially along an axis of rotation of a rotor, the stator having a first end and a second end, the first end and the second end being separated along the axis of rotation of the rotor, and providing stator windings arranged on the plurality of slots, the stator windings comprising a main set of windings, a first set of end turns near the first end, and a second set of end turns near the second end.The method also includes providing a cooling sleeve surrounding the stator windings, the cooling sleeve having a first opening near the first end of the stator, and a second opening near the second end of the stator, and providing a thermally conductive dissipation cap thermally connected to the cooling sleeve.

[0009] Any of the following features, or any combination thereof, may be used with the above examples. The cooling sleeve may include one or more cooling channels for the passage of cooling fluid inside the sleeve. A high thermal conductivity dielectric film may be disposed between the inside of the cooling sleeve and the stator windings, and the dielectric film may be in contact with both the cooling sleeve and the stator windings. The high thermal conductivity dielectric film may be one or more of a film based on polyoxydiphenylene-pyromellitimide, an Al2O3-based ceramic film, or a NiA1-based ceramic film. The thermally conductive heat dissipation cap may include a flange comprising a first inner surface configured to mate with an axial end of the first set of end turns, such that the thermally conductive heat dissipation cap includes a truncated cone connected to the flange, comprising a second inner surface configured to mate with the first set of end turns between the axial end of the first set of end turns and the main set of windings. The flange of the thermally conductive heat dissipation cap may come into direct contact with the first opening of the cooling sleeve.The heat dissipation cap may include a rear iron sleeve, the rear iron sleeve comprising a cylindrical section of heat-conducting material extending from the flange to the main winding assembly parallel to the axis of rotation. The motor may include a heat pipe connecting the cooling sleeve and the heat dissipation cap, such that the cooling sleeve and the heat dissipation cap do not come into direct contact with each other. The heat dissipation cap may include a rear iron sleeve, the rear iron sleeve comprising a cylindrical section of heat-conducting material extending from the cap to the main winding assembly parallel to the axis of rotation, such that the heat pipe extends from the rear iron sleeve to the cooling sleeve.The heat pipe is L-shaped and comes into contact with at least part of the cap.

[0010] Other technical features can be readily apparent to a person skilled in the art from the following figures, descriptions, and claims. Brief description of the drawings

[0011] For a more complete understanding of this disclosure, reference is made to the following description taken in conjunction with the accompanying drawings, in which:

[0012] Fig. 1 illustrates some technical problems addressed by embodiments according to the present disclosure;

[0013] Figures [Fig. 2A] to [Fig. 2G] illustrate examples of an engine using dissipation caps and cooling sleeves according to embodiments of the present disclosure; and

[0014] Figure 3 illustrates an example of a process according to this disclosure. DETAILED DESCRIPTION

[0015] Figures 1 to 3, described below, and the various embodiments used to describe the principles of this disclosure are provided for illustrative purposes only and shall not be construed in any way as limiting the scope of this disclosure. Those skilled in the art will understand that the principles of this disclosure can be implemented in any type of suitably arranged device or system.

[0016] As noted above, certain aircraft components, particularly compressors, rely on high-speed AC electric motors for their drive power. To achieve the required rotational speed, the underlying physics of electrical induction makes motors with a low pole count a highly preferable design choice. For example, a two-pole motor completes a full 360-degree revolution on a single polarity switch, whereas a four-pole motor rotates only 180 degrees on a single polarity switch. Thus, all other things being equal, fewer poles result in a higher rotational speed.

[0017] However, although the end turns of a motor do not, by themselves, produce electromagnetic force, the coil pitch of the end turns affects the electromagnetic field in the motor core, and achieving a suitable coil pitch in a two-pole motor requires longer end-turn windings. Again, all else being equal, a two-pole motor will have more insulated wire in its end turns than a comparable motor with more than two poles. Thus, end turns with comparatively larger volumes of insulated wire represent a generally unavoidable design consequence of motor design for maximum speed.

[0018] For information purposes and to illustrate certain technical issues addressed by embodiments according to this disclosure, [Fig. 1] shows a thermal map of a cross-section of a two-pole motor 100 that does not use the thermal management methods and apparatus of this disclosure. The motor 100 includes a stator 101 arranged inside a housing 103. The stator has windings around the core slots (for example, slot 105) as well as end-turn windings that extend upward and radially outward from the center of the core and occupy the region 107 inside the housing 103. The housing 103 also includes a first port 109a, which is configured to receive cooling air from a dynamic air supply fed by rapidly moving external air when the aircraft is in flight.The 103 case also includes a second port 109b, which is configured to receive cooling air from an onboard power supply. compressed air in high temperature / low airflow situations, for example when the aircraft is parked or taxiing.

[0019] As indicated by the closed shapes showing the isotherms inside the housing 103, region 107, despite the cooling air supply from either the first port 109a or the second port 109b, is significantly warmer than the regions inside the housing 103 closer to the first and second ports 109a and 109b. During rolling and low airflow operating scenarios, the measured and modeled temperatures for region 113 fluctuate around 140 °C, while the temperature in region 111 fluctuates around 190 °C, because the cooling airflow from the first port 109a and the second port 109b beyond the windings in region 111 is comparatively lower than in other areas inside the housing 103.Experience shows that, when maintained at temperatures above 140°C, typical insulating materials (e.g., baked epoxies) suitable for use in high-speed motors undergo thermal degradation, with the degradation rate doubling for every additional 10°C increase above 140°C. Thus, in this example, the insulation of the end-turn wires in region 111 is expected to wear out approximately sixteen times faster than that in region 113, presenting an undesirable risk of burning out motor 100 due to short circuits caused by thermally degraded insulation.

[0020] Figures 2A to 2G illustrate examples of a 200 engine using dissipation caps and cooling sleeves according to embodiments of this disclosure. For consistency and convenience of cross-referencing, elements common to several of Figures 2A to 2G are numbered similarly.

[0021] Figure 2A shows a compressor 205, which includes a motor 200. In this example, the compressor 205 is a centrifugal compressor, comprising a first wheel 299a and a second wheel which are driven by a drive shaft 295. In this example, a common housing 201 houses both the internal elements of the compressor 205 and the motor 200, although embodiments in which the motor 200 is housed separately from one or more components which it drives are possible, and within the envisaged scope of this disclosure. As shown in the figures, the housing 201 also includes one or more ports, such as port 203, for the intake and exhaust of cooling air from a dynamic air supply (for example, as the first port 109a in [Fig.l]) and / or from an on-board compressed air supply (for example, as described with reference to the second port 109b in [Fig.l]).The cooling air supplied by the first, second and third orifices enters the 201 case and, . at a minimum, passes over an external part of the motor 200, thus dissipating the heat generated by the passage of electric current through the windings of the motor 200.

[0022] Figure 2B provides a detailed cross-sectional view of an example of an engine 200, comprising a cooling sleeve 207 and first and second thermally conductive dissipation caps 230a and 230b, according to this disclosure. Figure 2C provides a detailed view of the thermally conductive dissipation cap 230a.

[0023] As described with reference to [Fig. 1], the challenges associated with supplying high-speed, low-pole AC motors are that these motors, compared to motors with more poles, have more insulated wire in the end-turn region, which is susceptible to accumulating destructive heat. As described herein, certain embodiments according to this disclosure provide improved thermal management for such motors through the use of a cooling sleeve that is, at a minimum, thermally connected to one or more thermally conductive heat sinks, which are themselves thermally connected to the end-turn windings and the cooling sleeve. Consequently, heat in the end-turn windings is dissipated to the thermally conductive heat sinks and then to the cooling sleeve.In this way, although the end-turn windings may generate more heat or experience less cooling airflow from port 203 than other parts of the motor 200, the combined action of the thermally conductive dissipation caps and the cooling sleeve means that the temperature in the "hot pockets" of the motor assembly (e.g., region 111 in [Fig. 1]) can be reduced by 40 °C or more, thus keeping motor windings significantly below the temperature regime (e.g., 180 °C or more) associated with accelerated insulation degradation.

[0024] With reference to the explanatory example in [Fig. 2B], the motor 200 comprises a rotor 293, which is connected to the drive shaft 295. The rotor 293 is configured to rotate about the axis of rotation 291 in response to a magnetomotive force generated in an air gap between the rotor 293 and the insulated wire windings on a plurality of slots in the stator 209. In this example, the insulated wire windings on the stator 209 may be arranged in a low-pole configuration (e.g., two-pole or four-pole), in which each winding comprises a set of main windings 211b that are arranged across the air gap 213 from the rotor 293. Each winding also comprises a first set of end turns 21a at a first end 215a of the stator 209, and a second set of end turns 211c arranged at a second end 215b of the stator 209.As illustrated in the figure, the first set. The first set of end turns 21a and the second set of end turns 211c are axially adjacent to the main windings 211b. In this illustrative example, the motor 200 also includes a back iron 217, comprising a section of iron or other ferromagnetic material supporting the stator slots 209 near the main windings 211b.

[0025] The person skilled in the art will appreciate that, during the normal operation of the motor 200 by generating a magnetomotive force on the transmission shaft 295 and the wheels 299a and 299b, the passage of electric current through the main windings 211b, the winding of the first end turn 21la and the second end turn 211c necessarily causes heating by Joule effect, increasing the temperature of the motor in and around the current-carrying wires carried on the stator 209.

[0026] To eliminate the heat accumulated due to Joule heating in the windings of the motor 200, the stator 209 is arranged inside a cooling sleeve 207, which may be a cylindrical section of thermally conductive material, such as stainless steel (for example, SS-300 stainless steel) which surrounds the stator 209 around the main windings 211b, and according to embodiments, extends axially towards the first end turn 21la and the second end turn 21le, terminating with a first opening 219a near the first end turn 21la, and a second opening 219b near the second end turn 211c. In some embodiments, the cooling sleeve 207 includes one or more cooling channels 221 through which a coolant can flow to, from and within the cooling sleeve 207.Suitable coolants include, but are not limited to, oil and dielectric coolants (e.g., diethylbenzene [DEB], dibenzyltoluene, diarylalkyl, partially hydrogenated terphenyl, silicate esters, and silicone oil). As shown in the figures, one or more O-rings 223a and 223b may be used to seal the coolant inside the cooling sleeve 207. Other examples of suitable coolants include, but are not limited to, water-based coolants (e.g., ethylene glycol or propylene glycol) and refrigerants.

[0027] As illustrated in Figures 2B and 2C, the inside of the cooling sleeve 207 is dimensioned to generally conform to an outer profile of the main windings 211b and the first and second end turns 21a and 211c, but not necessarily to touch (i.e., be in thermally conductive contact with) the actual windings. To ensure thermal conduction between the cooling sleeve 207 and the heat-generating windings of the motor 200, A layer of dielectric film or dielectric buffer 227 is disposed between the windings (e.g., the winding of the first end turn 21la and the cooling sleeve 207) such that the dielectric buffer 227 fills all the spaces between the cooling sleeve 207 and the winding and draws heat from the windings to the cooling sleeve. Examples of suitable materials for the dielectric buffer 227 include, but are not limited to, poly-oxydiphenylene-pyromellitimide-based films (e.g., KAPTON®), Al₂O₃-based ceramic films, or AlN-based ceramic films.

[0028] As illustrated in Figures 2B and 2C, the motor 200 also includes one or more heat dissipation caps, comprising a first thermally conductive heat dissipation cap 230a disposed near the winding of the first end turn 21la and a second thermally conductive heat dissipation cap 230b disposed near the second end turn 21le. In this example, the first and second thermal dissipation caps 230a and b comprise an annular section (i.e., having a hole in the middle for the passage of the drive shaft 295) made of a thermally conductive material, such as aluminum or aluminum nitride (AIN), which includes a flange 231 and a frustoconical portion 233. It should be noted that, in some embodiments, the flange 231 may be omitted and the first or second thermally conductive heat dissipation caps 230a and 230b may have a flat annular shape.The flange 231 includes an inner surface 235, which is proportioned to mate with an axial end of the first or second set of end turns. Similarly, the frustoconical portion 233 includes a second inner surface 237 that is configured to mate with an inner portion (i.e., closer to the drive shaft 295) of the end turns. As with the cooling sleeve 207, one or more dielectric pads or layers of thermally conductive material 239a and 239b can be interposed to fill the space between the end turn windings and the first and second inner surfaces 235 and 237 and maintain conductive thermal contact between the end turn windings and the thermally conductive dissipation caps 230a and 230b.

[0029] During operation, the Joule heat generated in the end-turn windings (e.g., the first end turn 211a) flows conductively through the heat dissipation caps (e.g., the first thermally conductive heat dissipation cap 230a) and is then directed to the cooling sleeve 207. In this way, certain embodiments according to this disclosure provide improved heat rejection of the Joule heat developed in the windings (in particular, the end turns) of the motor 200, by "covering the corners" of the cooling cover and providing a thermally conductive path from the thermally conductive dissipation paths to the cooling sleeve 207 which can be liquid-cooled and / or more directly into the airflow path of the air ports (e.g., port 203 in housing 201).

[0030] According to the embodiments, the thermally conductive path from the thermally conductive heat sinks 230a and 230b to the cooling sleeve 207 can be provided by a variety of structures. In the example shown in Figures 2A to 2C, the flange 231 makes direct contact with the cooling sleeve 207 along the first opening 219a and the second opening 219b. Thus, the outer edges of the cooling sleeve 207 are the thermal contact points between the thermally conductive heat sinks 230a and 230b and the cooling sleeve 207. However, this disclosure encompasses additional embodiments, including embodiments in which the cooling sleeve 207 does not extend to the axial ends of either of the windings of the first end turn 211a or the second end turn 211c.

[0031] Figure 2D illustrates, in partial cross-section, an example of an embodiment showing an alternative structure for a thermally conductive path from the first and second thermally conductive heat sinks 230a and 230b to the cooling sleeve 207 according to the present disclosure. As shown in the figure, in the example of Figure 2D, the cooling sleeve 207 is axially shorter compared to the embodiments shown in Figures 2A to 2C and is generally coextensive with the back iron 217 and the main windings 211b and does not, by itself, reach the flanges of the first and second thermally conductive heat sinks 230a and 230b. Consequently, and as illustrated in Figure 2D, the first and second thermally conductive heat sinks 230a and 230b comprise first and second back iron sleeves 241a and 241b, respectively.As shown in the figure, each of the rear iron sleeves 241a and 241b extends from the respective flanges of the first and second thermally conductive dissipation caps 230a and 230b to meet at the first opening 219a and the second opening 219b, respectively. Tests have confirmed that, in this arrangement, temperature drops in the end-turn windings of the order of 30 °C or more compared to the temperatures shown in the example in [Fig. 1] are observed, meaning that shortening the cooling sleeve 207 as illustrated in [Fig. 2D] still eliminates the destructive "hot spots" in the end-turn windings described with reference to [Fig. 1].

[0032] Figures 2E to 2G illustrate examples of other embodiments according to the present disclosure, in which, instead of thermally connecting the first and second heat-conducting dissipation caps 230a and 230b to the cooling sleeve via the rear iron sleeves 241a and 241b, the motor 200 can be lightened by replacing some of the material of the rear iron sleeves 241a and 241b with heat pipes to connect the heat-conducting dissipation caps 230a and 230b to the cooling sleeve 207.

[0033] With reference to the illustrative examples in Figures 2E to 2G, the rear iron sleeves 241a and 241b can be axially shortened (compared to the example in [Fig. 2D]), to leave a first gap 243a between the cooling sleeve 207 and the first heat-conducting dissipation cap 230a and a second gap 243b between the cooling sleeve 207 and the second heat-conducting dissipation cap 230b. As shown in the figures, instead of a full cylindrical section of material, sufficient thermal contact to keep the windings of the motor 200 out of the destructive temperature regimes described with reference to [Fig. 1] can be obtained by filling the gaps with one or more heat pipes (for example, the first heat pipe 245a and the second heat pipe 245b).Each of the heat pipes 245a and 245b may comprise solid or hollow sections (e.g., cylindrical, square or star-shaped (to increase the surface area)) of a highly conductive material, such as aluminium or aluminium nitride.

[0034] According to embodiments, the first and second heat pipes 245a and 245b can connect to the first and second thermally conductive dissipation caps 230a and 230b at the rear iron sleeves 241a and 241b, as illustrated in Figures 2E and 2F. Alternatively, the first and second 245a and 245b can extend to the flange 231 for improved heat dissipation in the axially outermost portions of the end coils, as illustrated in [Fig. 2G]. While the illustrative examples in Figures 2E to 2G show embodiments with only two heat pipes, the present disclosure considers and encompasses more heat pipes (e.g., ten).

[0035] Figure 3 illustrates the operations of an example method 300 for providing thermal management of an electric motor according to this disclosure.

[0036] With reference to the non-limiting example in [Fig. 3], in operation 305, a housing for a motor (for example, housing 201) is provided. Depending on the embodiment, the housing provided in operation 305 may have one or more openings for the passage of cooling air (for example, dynamic air or air from a compressed air supply). In some embodiments, the housing provided in operation 305 may be integrated into one or more components driven by the motor (such as a compressor).

[0037] In operation 310, a stator is provided, the stator comprising a plurality of slots arranged axially along an axis of rotation of a rotor configured to rotate in an air gap between an inner portion of the stator and the outer portion of the rotor. In some embodiments, the stator provided in operation 310 is a "low-pole" stator configured to be wound with only two or four poles, in order to maximize the angular travel of the rotor between the phase switches.

[0038] In operation 315, stator windings are provided according to the polar structure (for example, two or four poles) of the stator. The stator windings provided in operation 315 comprise a main set of windings that are radially adjacent to the motor rotor, and a first set of end turns that are axially adjacent to the main set of windings and located near a first end of the stator. The stator windings provided in operation 315 also comprise a second set of end turns that are axially adjacent to the main set of windings and located near a second end of the stator, such that the first set of end turns is axially separated from the second set of end turns by the main set of windings.

[0039] In operation 320, a cooling sleeve (for example, the cooling sleeve 207 in Figures 2A to 2G) is provided, such that the cooling sleeve surrounds the stator windings. The cooling sleeve may surround the main winding assembly and, in some embodiments, the cooling sleeve extends axially beyond the main winding assembly, either partially or completely to the ends of the end turns.

[0040] In operation 325, one or more thermally conductive dissipation caps are provided, each of the one or more thermally conductive dissipation caps being thermally connected to the cooling sleeve. As described with reference to Figures 2A to 2G, embodiments according to this disclosure include, but are not limited to, achieving thermal contact by direct contact between the openings of the cooling sleeve and the flanges of the one or more thermally conductive dissipation caps (for example, as illustrated in [Fig. 2C]), achieving thermal contact via a back iron sleeve in contact with a shortened cooling sleeve (for example, as illustrated in [Fig. 2D]), or using one or more heating tubes to fill a gap between the one or more thermally conductive dissipation caps and the cooling sleeve.

[0041] It may be advantageous to establish definitions for certain words and expressions used in this patent document. The terms "contain" and "include", as well and their derivatives, signify inclusion without limitation. The term "or" is inclusive, meaning both and / or. The expression "associated with," as well as its derivatives, can mean to include, to be included in, to interconnect with, to contain, to be contained in, to connect to or with, to couple with or with, to be communicable with, to cooperate with, to intertwine, to juxtapose, to be close to, to be related to or with, to have, to have a property of, to have a relationship with or with, or similar. The expression "at least one of," when used with a list of items, means that different combinations of one or more of the listed items can be used, and that only one item from the list may be necessary. For example, "at least one of: A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0042] The description in this disclosure shall not be construed as implying that any particular element, step, or function is an essential or critical element that must be included within the scope of the claim. The scope of the patented subject matter is defined solely by the permitted claims.

[0043] Although this disclosure has described certain embodiments and generally associated methods, modifications and permutations of these embodiments and methods will be obvious to those skilled in the art. Accordingly, the above description of examples of embodiments does not define or restrict this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.

Claims

Demands

1. Motor (100; 200), the motor (100; 200) comprising: a housing (103; 201); a stator (101; 209) with a plurality of slots arranged axially along an axis of rotation (291) of a rotor (293), the stator (101; 209) having a first end (215a) and a second end (215b), in which the first end (215a) and the second end (215b) are separated along the axis of rotation (291) of the rotor (293); stator windings (101; 209) arranged on the plurality of slots, the stator windings (101; 209) comprising a main set of windings (211b), a first set of end turns (21la) near the first end (215a) and a second set of end turns (21le) near the second end (215b); a cooling sleeve (207) surrounding the stator windings (101;209), the cooling sleeve (207) having a first opening (219a) near the first end (215a) of the stator (101; 209), and a second opening (219b) near the second end (215b) of the stator (101; 209); and a thermally conductive dissipation cap (230a, 230b) thermally connected to the cooling sleeve (207).

2. Engine (100; 200) according to claim 1, wherein the cooling sleeve (207) comprises one or more cooling channels (221) for the passage of cooling fluid inside the sleeve (207).

3. Motor (100; 200) according to claim 1, wherein a high thermal conductivity dielectric film (227) is disposed between the inside of the cooling sleeve (207) and the stator windings (101; 209), and wherein the dielectric film (227) comes into contact with both the cooling sleeve (207) and the stator windings (101; 209).

4. Motor (100; 200) according to claim 3, wherein the high thermal conductivity dielectric film (227) comprises one or more of a poly-oxydiphenylene-pyromellitimide based film, of an Al2O3-based ceramic film or an AlN-based ceramic film.

5. Motor (100; 200) according to claim 1, wherein the heat-conducting dissipation cap (230a, 230b) comprises a flange (231), comprising a first inner surface (235) configured to mate with an axial end of the first set of end turns (211a), wherein the heat-conducting dissipation cap (230a, 230b) comprises a truncated cone connected to the flange (231), comprising a second inner surface (237) configured to mate with the first set of end turns (211a) between the axial end of the first set of end turns (211a) and the main set of windings (211b).

6. Motor (100; 200) according to claim 5, wherein the flange (231) of the heat-conducting dissipation cap (230a, 230b) comes into direct contact with the first opening (219a) of the cooling sleeve (207).

7. Motor (100; 200) according to claim 5, wherein the heat-conducting dissipation cap (230a, 230b) comprises a rear iron sleeve, the rear iron sleeve comprising a cylindrical section of heat-conducting material extending from the flange (231) to the main winding assembly (211b) parallel to the axis of rotation (291).

8. Motor (100; 200) according to claim 1, also comprising a heat pipe (245a, 245b) connecting the cooling sleeve (207) and the thermally conductive dissipation cap (230a, 230b), wherein the cooling sleeve (207) and the thermally conductive dissipation cap (230a, 230b) are not directly in contact with each other.

9. Motor (100; 200) according to claim 8, wherein the heat-conducting dissipation cap (230a, 230b) comprises a rear iron sleeve, the rear iron sleeve comprising a cylindrical section of heat-conducting material extending from the cap (230a, 230b) to the main winding assembly (211b) parallel to the axis of rotation (291), and wherein the heat pipe (245a, 245b) extends from the rear iron sleeve to the cooling sleeve (207).

10. Motor (100; 200) according to claim 9, wherein the heat pipe (245a, 245b) is L-shaped and comes into contact with at least a part of the cap (230a, 230b).

11. Device comprising: a cooling sleeve (207), comprising a section of a thermally conductive material having a first opening (219a) proportioned to accommodate a first end (215a) of a stator (101; 209), and a second opening (219b) proportioned to accommodate a second end (215b) of the stator (101; 209); and a thermally conductive dissipation cap (230a, 230b) thermally connected to the cooling sleeve (207).

12. Device according to claim 11, wherein the cooling sleeve (207) comprises one or more cooling channels (221) for the passage of cooling fluid inside the sleeve (207).

13. Apparatus according to claim 11, also comprising a high thermal conductivity dielectric film (227) disposed on an inner surface (235) of the cooling sleeve (207), and in which the dielectric film (227) is proportioned simultaneously to the cooling sleeve (207) and to the stator windings (101; 209).

14. Apparatus according to claim 13, wherein the high thermal conductivity dielectric film (227) comprises one or more of a poly-oxydiphenylene-pyromellitimide-based film, an Al2O3-based ceramic film or an AlN-based ceramic film.

15. Device according to claim 11, wherein the heat-conducting dissipation cap (230a, 230b) comprises a flange (231), comprising a first inner surface (235) configured to mate with an axial end of a set of end turns of the stator (101; 209), wherein the heat-conducting dissipation cap (230a, 230b) comprises a truncated cone connected to the flange (231), comprising a second inner surface (237) configured to mate with the set of end turns between the axial end of the set of end turns and a main set of stator windings (101; 209).

16. Device according to claim 15, wherein the flange (231) of the heat-conducting dissipation cap (230a, 230b) between directly in contact with the first opening (219a) of the cooling sleeve (207).

17. Device according to claim 15, wherein the thermally conductive dissipation cap (230a, 230b) comprises a rear iron sleeve, the rear iron sleeve comprising a cylindrical section of thermally conductive material extending from the flange (231) to the main winding assembly (211b) of the stator (101; 209).

18. Device according to claim 11, also comprising a heat pipe (245a, 245b) connecting the cooling sleeve (207) and the thermally conductive dissipation cap (230a, 230b), wherein the cooling sleeve (207) and the thermally conductive dissipation cap (230a, 230b) are not directly in contact with each other.

19. Apparatus according to claim 18, wherein the heat-conducting dissipation cap (230a, 230b) comprises a rear iron sleeve, the rear iron sleeve comprising a cylindrical section of heat-conducting material extending from the cap (230a, 230b) to the main winding assembly (211b) of the stator (101; 209), and wherein the heat pipe (245a, 245b) extends from the rear iron sleeve to the cooling sleeve (207).

20. Apparatus according to claim 19, wherein the heat pipe (245a, 245b) is in the shape of an "L" and comes into contact with at least a part of the cap (230a, 230b).

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