WO2024099591A1

WO2024099591A1 - Internally cooled coils and housing for an electric machine

Info

Publication number: WO2024099591A1
Application number: PCT/EP2023/025466
Authority: WO
Inventors: Jacob Abraham KALLIVAYALIL; Anand Sathyan; Jie Li; Mihai Dorobantu; Lucas David STAHL; Michael Christopher TAYLOR
Original assignee: Eaton Intelligent Power Limited
Priority date: 2022-11-08
Filing date: 2023-11-08
Publication date: 2024-05-16

Abstract

An electric machine includes a rotor and a stator that includes an array of coil windings. Each coil winding includes a tubular body configured to allow dielectric fluid to move therethrough. The electric machine may further include a housing formed around an outer circumference of the array of coil windings of the stator and fluid channels to cool the dielectric fluid. Each coil winding of the array of coil windings may further include a first stator fluid opening at a top end the tubular body and a second stator fluid opening at a bottom end of the tubular body. Each coil winding of the array of coil windings may further include a third stator fluid opening at a middle location of the tubular body. The stator fluid openings can be fluidically coupled to the housing.

Description

INTERNALLY COOLED COILS AND HOUSING FOR AN ELECTRIC MACHINE

GOVERNMENT RIGHTS NOTICE

[0001] This invention was made with government support under U.S. Army TARDEC, DoD Subcontract 2020110-142030 under Contract HQ0034-20-2-0007. The government may have certain rights in the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63/423,577, filed November 8, 2022.

BACKGROUND

[0003] With the normalization of hybrid and electric vehicles and other applications requiring electric machines that can achieve high torque density and high power density simultaneously, electric machines become thermally limited in that peak power and/or torque can only be maintained for only a short time due to the inability to dissipate heat generated by the electric machine. The heat generated results in temperature hot spots which lead to the deterioration of the winding insulation, increased risk of demagnetization, and/or failure of electric machine components, such as bearings. Furthermore, space within applications using electric machines (e.g., vehicles) comes at a premium with battery systems and other required systems needing as much space as possible. Accordingly, there is a need for solutions to effectively and efficiently dissipate heat generated by high torque density and high power density of electric machines.

BRIEF SUMMARY

[0004] Electric machines with internally cooled coil windings in stator arrays and internally cooled housings are disclosed herein. Advantageously, the disclosed internally cooled coil windings in the stator allow for dielectric fluid to move within tubular bodies of the coil windings to dissipate heat generated by the electric machine, with the stator itself acting as a heat exchanger. Similarly, the internally cooled housing allows for dielectric fluid to move within internal channels (e.g., cooling fins) to further dissipate heat generated by the electric machine. These internally cooled coil windings in stator arrays and internally cooled housings allow for smaller separate heat exchangers (e.g., radiators) or even the elimination of separate heat exchangers in electric machine applications, providing valuable space for other required systems used in electric machine applications.

[0005] An electric machine includes a rotor and a stator that includes an array of coil windings. Each coil winding includes a tubular body configured to allow dielectric fluid to move therethrough.

[0006] In some cases, the electric machine further includes a housing formed around an outer circumference of the array of coil windings of the stator. In some cases, the housing includes a fluidic channel, a first stator housing fluid opening providing a first fluid inlet or outlet to the fluidic channel of the housing, the first stator housing fluid opening fluidically coupled to one coil winding of the array of coil windings, and a second stator housing fluid opening providing a second fluid inlet or outlet to the fluidic channel of the housing, the second stator housing fluid opening fluidically coupled to one coil winding of the array of coil windings. In some cases, the one coil winding of the array of coil windings to which the second stator housing fluid opening is fluidically coupled is a different coil winding than the one coil winding of the array of coil windings to which the first stator housing fluid opening is fluidically coupled.

[0007] In some cases, the housing further includes one or more third stator housing fluid openings providing one or more third fluid inlets or outlets to the fluidic channel of the housing, the one or more third stator housing fluid openings fluidically coupled to a middle location of one or more coil windings of the array of coil windings. In some cases, at least one of the first, second, and third stator housing fluid openings are fluidically coupled to at least every third coil winding of the array of coil windings. In some cases, at least one of the first, second, and third stator housing fluid openings are fluidically coupled to every coil winding of the array of coil windings. In some cases, the fluidic channel of the housing includes internal conformal cooling channels located within a plurality of cooling fins. In some cases, the electric machine further includes a first dielectric fluid distribution manifold coupled to a first flat end of the stator housing, a second dielectric fluid distribution manifold coupled to a second flat end of the stator housing. In some cases, the first dielectric fluid distribution manifold and the second dielectric fluid distribution manifold are fluidically coupled to an external heat exchanger or pump to move the dielectric fluid therethrough.

[0008] In some cases, the electric machine further includes a pump configured to circulate the dielectric fluid through each of the array of coil windings of the stator. In some cases, each coil winding further includes a first stator fluid opening providing a first fluid inlet or outlet, the first stator fluid opening at a top end the tubular body, a second stator fluid opening providing a second fluid inlet or outlet, the second stator fluid opening at a bottom end of the tubular body, and a third stator fluid opening providing a third fluid inlet or outlet, the third stator fluid opening at a middle location of the tubular body, whereby dielectric fluid is able to move from the first stator fluid opening, through the top end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on a pump operation, and whereby dielectric fluid is able to move from the second stator fluid opening, through the bottom end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on the pump operation.

[0009] In some cases, the third stator fluid opening of each coil winding includes an interior dividing wall such that dielectric fluid moving from first stator fluid opening to the middle location of the tubular body does not come into contact with dielectric fluid moving from the second stator fluid opening to the middle location of the tubular body within a corresponding coil winding. In some cases, the third stator fluid opening of each coil winding allows for dielectric fluid moving from the first stator fluid opening to the middle location of the tubular body to contact with dielectric fluid moving from the second stator fluid opening to the middle location of the tubular body.

[0010] A stator for an electric machine includes an array of coil windings. Each coil winding includes a tubular body configured to allow dielectric fluid to move therethrough.

[0011] In some cases, each coil winding of the array of coil windings further includes a first stator fluid opening providing a first fluid inlet or outlet, the first stator fluid opening at a top end the tubular body and a second stator fluid opening providing a second fluid inlet or outlet, the second stator fluid opening at a bottom end of the tubular body. In some cases, each coil winding of the array of coil windings further includes a third stator fluid opening providing a third fluid inlet or outlet, the third stator fluid opening at a middle location of the tubular body, whereby dielectric fluid is able to move from the first stator fluid opening, through the top end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on a pump operation; and dielectric fluid is able to move from the second stator fluid opening, through the bottom end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on the pump operation. [0012] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 illustrates a dual rotor axial flux electric machine.

[0014] Figures 2A-2D illustrate unidirectional flow stator coil windings.

[0015] Figures 3A-3D illustrate bidirectional flow stator coil windings.

[0016] Figures 4A-4C illustrate bidirectional flow stator coil windings.

[0017] Figure 5A illustrates an outer portion of an electric machine housing.

[0018] Figure 5B illustrates an inner portion of an electric machine housing.

[0019] Figure 6A illustrates an electric machine housing.

[0020] Figure 6B a neutron radiograph of an internal channel in an electric machine housing.

[0021] Figure 6C and 6D illustrate views of internal channels of positioned in cooling fins of an electric machine housing.

[0022] Figure 7 illustrates unidirectional flow stator coil windings coupled to an electric machine housing with a plurality of cooling fins.

[0023] Figure 8A illustrates a side angled view of an array of coil windings coupled to an electric machine housing.

[0024] Figure 8B illustrates a side angled view of an electric machine housing.

[0025] Figure 9A illustrates a stator coupled to an electric machine housing having a coolant distribution manifold.

[0026] Figures 9B illustrates a coolant distribution manifold.

[0027] Figure 9C illustrate internal channels in a coolant distribution manifold.

DETAILED DESCRIPTION

[0028] Electric machines with internally cooled coil windings in stator arrays and housings are disclosed herein. Advantageously, the disclosed internally cooled coil windings in the stator allow for dielectric fluid to move within tubular bodies of the coil windings to dissipate heat generated by the electric machine, with the stator itself acting as a heat exchanger. Similarly, the internally cooled housing allows for dielectric fluid to move within internal channels (e.g., cooling fins) to further dissipate heat generated by the electric machine. These internally cooled coil windings in stator arrays and internally cooled housings allow for smaller separate heat exchangers (e.g., radiators) or even the elimination of separate heat exchangers in electric machine applications, providing valuable space for other required systems used in electric machine applications.

[0029] In all embodiments, coil windings are electrically isolated from the electric machine housing. The coil windings can be electrically isolated from and fluidically connected to the electric machine housing using electrically non-conducting couplings. The coil windings are themselves electrically connected to the electric machine by suitable busbar and terminations arrangements to reflect the phase configuration of the electric machine. In some embodiments, a power greater than 200 kilowatts may be considered high power. In some embodiments, an energy density greater than 20 kilowatts per liter may be considered high energy density. At these power and power density readings from a typical efficiency motor, about 15 to 20 kW of thermal energy would have to be dissipated. The example power ratings are illustrative and non-limiting. A typical coolant (e.g., dielectric fluid) flow rate, which may depend on one or more of the application or ram air, may be about 8 liters per minute.

[0030] Figure 1 illustrates a dual rotor axial flux electric machine. Referring to Figure 1, an electric machine 100 includes a first rotor 102, a second rotor 104, and an array of coil windings 106. Each coil winding of the array of coil windings 106 includes a tubular body configured to allow dielectric fluid to move therethrough. In some cases, an electric machine 100 includes a single rotor (e.g., first rotor 102). In some cases, an electric machine 100 includes a housing (e.g., as described with respect to Figures 5A-9C below).

[0031] As used herein, unidirectional flow refers to a flow of liquid (e.g., dielectric fluid) through a body (e.g., a tubular body of a coil winding) in a single direction (e.g., from a top to a bottom of the body or from a bottom to a top of the body) at a time. However, the direction of that flow of liquid may reverse at any time (e.g., according to a pump operation).

[0032] As used herein, bidirectional flow refers to a flow of liquid (e.g., dielectric fluid) through a body (e.g., a tubular body of a coil winding) in more than one direction (e.g., from a top to a bottom of the body or from a bottom to a top of the body) at a time. For example, fluid can flow in a first direction through a first portion and/or section of a body (e.g., from a top to a bottom of that first portion and/or section of the body) while fluid flows in a second direction through a second portion and/or section of the body (e.g., from a bottom to a top of that second portion and/or section of the body) at the same time. The direction of that flow of liquid through that portion and/or section of the body may reverse at any time (e.g., according to a pump operation). [0033] In either case, direction of flow may be dependent upon operation of the electric machine (e.g., low speed vs. high speed) and/or a pump operation.

[0034] Figures 2A-2D illustrate unidirectional flow stator coil windings. Referring to Figure 2A, three unidirectional flow stator coil windings 200 are illustrated. Each unidirectional flow stator coil winding 200 includes a tubular body 202 that allows dielectric fluid to move therethrough, a first stator fluid opening 204 providing a first fluid inlet or outlet at a top end 206 of the tubular body 202, and a second stator fluid opening 208 providing a second fluid inlet or outlet at a bottom end 210 of the tubular body 202.

[0035] Referring to Figure 2B, a unidirectional flow stator coil winding 220 includes a tubular body 222 having a dielectric fluid 232 moving therethrough, a first stator fluid opening 224 providing a first fluid inlet or outlet at a top end 226 of the tubular body 222, and a second stator fluid opening 228 providing a second fluid inlet or outlet at a bottom end 230 of the tubular body 222. In this specific example, the second stator fluid opening 228 provides a fluid inlet for the dielectric fluid 232 and the first stator fluid opening 224 provides a fluid outlet for the dielectric fluid 232. The direction of the flow of the dielectric fluid 232 into the second stator fluid opening 228, through the bottom end 230 of the tubular body 222 to the top end 226 of the tubular body 222, and out of the first stator fluid opening 224 may be reversed according to a pump operation. [0036] Temperature distribution (in Celsius) throughout the tubular body 222 having the dielectric fluid 232 moving therethrough (e.g., at a particular flow rate) as well as the temperature of the dielectric fluid 232 being received at the second stator fluid opening 228 and discharged at the first stator fluid opening 224 is illustrated.

[0037] Referring to Figure 2C, a unidirectional flow stator coil winding 240 includes a tubular body 242 having a dielectric fluid moving therethrough, a first stator fluid opening 244 providing a first fluid inlet or outlet at a top end 246 of the tubular body 242, and a second stator fluid opening 248 providing a second fluid inlet or outlet at a bottom end 250 of the tubular body 242. [0038] A pressure drop (in pounds per square inch) to move dielectric fluid through the tubular body 242 (e.g., at a particular flow rate) is illustrated. A pump to move/circulate the dielectric fluid through each unidirectional flow stator coil winding 240 of an array of coil windings of the stator can be chosen accordingly.

[0039] Referring to Figure 2D, a cross section of a unidirectional flow stator coil winding 260 that includes a tubular body 262 that allows dielectric fluid to move therethrough, a portion of a rotor 264, and a structural connection 266 are illustrated. Variation in current density throughout the tubular body 262 of the unidirectional flow stator coil winding 260 is shown to decrease as a distance D from an air gap 268 between the unidirectional flow stator coil winding 260 and the portion of the rotor 264 increases.

[0040] Figures 3A-3D illustrate bidirectional flow stator coil windings. Referring to Figure 3A, three bidirectional flow stator coil windings 300 are illustrated. Each bidirectional flow stator coil winding 300 includes a tubular body 302 that allows dielectric fluid to move therethrough, a first stator fluid opening 304 providing a first fluid inlet or outlet at a top end 306 of the tubular body 302, a second stator fluid opening 308 providing a second fluid inlet or outlet at a bottom end 310 of the tubular body 302, and a third stator fluid opening 312 providing a third fluid inlet or outlet at a middle location 314 of the tubular body 302. Dielectric fluid is able to move from the first stator fluid opening 304, through the top end 306 of the tubular body 302 to the middle location 314 of the tubular body 302, and out the third stator fluid opening 312 and vice versa depending on a pump operation, and dielectric fluid is able to move from the second stator fluid opening 308, through the bottom end 310 of the tubular body 302 to the middle location 314 of the tubular body 302, and out the third stator fluid opening 312 and vice versa depending on the pump operation.

[0041] Referring to Figure 3B, a bidirectional flow stator coil winding 320 includes a tubular body 322 that allows dielectric fluid to move therethrough, a first stator fluid opening 324 providing a first fluid inlet or outlet at a top end 326 of the tubular body 322, a second stator fluid opening 328 providing a second fluid inlet or outlet at a bottom end 330 of the tubular body 322, and a third stator fluid opening 332 providing a third fluid inlet or outlet at a middle location 334 of the tubular body 322. Dielectric fluid 336 is illustrated moving from the first stator fluid opening 324, through the top end 326 of the tubular body 322 to the middle location 334 of the tubular body 322, and out the third stator fluid opening 332. Dielectric fluid 338 is able to move from the second stator fluid opening 328, through the bottom end 330 of the tubular body 322 to the middle location 334 of the tubular body 322, and out the third stator fluid opening 332. As explained above, this flow may be reversed depending on a pump operation.

[0042] Temperature distribution (in Celsius) throughout the tubular body 322 having the dielectric fluid 336, 338 moving therethrough (e.g., at a particular flow rate) as well as the temperature of the dielectric fluid 336 being received at the first stator fluid opening 324 and discharged at the third stator fluid opening 332 and dielectric fluid 338 being received at the second stator fluid opening 328 and discharged at the third stator fluid opening 332 is illustrated. [0043] As compared with unidirectional flow cooling (e.g., as illustrated in Figure 2B), bidirectional flow cooling illustrated in Figure 3B enables more effective cooling where current density (e.g., as illustrated in Figure 2D) is highest.

[0044] Referring to Figure 3C, a bidirectional flow stator coil winding 340 includes a tubular body 342 that allows dielectric fluid to move therethrough, a first stator fluid opening 344 providing a first fluid inlet or outlet at a top end 346 of the tubular body 342, a second stator fluid opening 348 providing a second fluid inlet or outlet at a bottom end 350 of the tubular body 342, and a third stator fluid opening 352 providing a third fluid inlet or outlet at a middle location 354 of the tubular body 342.

[0045] A pressure drop (in pounds per square inch) to move the dielectric fluid through the tubular body 342 (e.g., from the third stator fluid opening 352, through the middle location 354 of the tubular body 342 to the top end 346 of the tubular body 342 and out the first stator fluid opening 344; and from the third stator fluid opening 352, through the middle location 354 of the tubular body 342 to the bottom end 350 of the tubular body 342, and out the second stator fluid opening 348) at a particular flow rate is illustrated. A pump to move/ circulate the dielectric fluid through each bidirectional flow stator coil winding 340 of an array of coil windings of the stator can be chosen accordingly.

[0046] As compared with the unidirectional flow pressure drop (e.g., as illustrated in Figure 2C), the pressure drop of the bidirectional flow is significantly reduced as a length of the tubular body 342 is essentially cut in half. This enables more efficient operation as power required to pump the fluid at a particular flow rate is significantly reduced (e.g., the pump may be parasitic to the electric machine) and can lead to a smaller pump being chosen, saving/providing valuable space for other required systems used in electric machine applications.

[0047] Referring to Figure 3D, a cross section of a tubular body 360 of a bidirectional flow coil winding 362 at a middle location 364 is illustrated. A third stator fluid opening 366 includes an interior dividing wall 370 such that dielectric fluid moving from the first stator fluid opening (not illustrated in this Figure) to the middle location 364 of the tubular body 360 does not come into contact with dielectric fluid moving from the second stator fluid opening 368 to the middle location 364 of the tubular body 360. This allows for dielectric fluid from the first stator fluid opening and the second stator fluid opening 368 to be kept separate (e.g., to flow to different coil windings and/or different locations in an internally cooled housing/manifold) if so desired. Alternatively, the third stator fluid opening 366 can be fluidically coupled to a same fluid moving mechanism (e.g., dielectric fluid hose) such that the dielectric fluid from the first stator fluid opening and the second stator fluid opening 368 are mixed within the fluid moving mechanism. It should be noted that the third stator fluid opening 366, 312, 332, 352 having the interior dividing wall 370 is illustrated in Figures 3A-3C, but the interior dividing wall 370 is not given a reference number in Figures 3A-3C for purposes of this discussion.

[0048] Figures 4A-4C illustrate bidirectional flow stator coil windings. Referring to Figures 4A-4C, a bidirectional flow stator coil winding 400 includes a tubular body 402 that allows dielectric fluid to move therethrough, a first stator fluid opening 404 providing a first fluid inlet or outlet at a top end 406 of the tubular body 402, a second stator fluid opening 408 providing a second fluid inlet or outlet at a bottom end 410 of the tubular body 402, and a third stator fluid opening 412 providing a third fluid inlet or outlet at a middle location 414 of the tubular body 402. Dielectric fluid is able to move from the first stator fluid opening 404, through the top end 406 of the tubular body 402 to the middle location 414 of the tubular body 402, and out the third stator fluid opening 412 and vice versa depending on a pump operation, and dielectric fluid is able to move from the second stator fluid opening 408, through the bottom end 410 of the tubular body 402 to the middle location 414 of the tubular body 402, and out the third stator fluid opening 412 and vice versa depending on the pump operation.

[0049] In this embodiment, the third stator fluid opening 412 allows for dielectric fluid moving from the first stator fluid opening 404 to the middle location 414 of the tubular body 402 to contact with dielectric fluid moving from the second stator fluid opening 408 to the middle location 414 of the tubular body 402 within the bidirectional flow stator coil winding 400 (e.g., within the third stator fluid opening 412 itself because there is no interior dividing wall (e.g., interior dividing wall 370) as illustrated in Figure 4C.

[0050] A cross-section of the tubular body 402 (e.g., as illustrated in Figure 4B) and cross sections of the first stator fluid opening 404, the second stator fluid opening 408, and the third stator fluid opening 412 (e.g., as illustrated in Figure 4A) have a rectangle tubular cross section. This should not be seen as limiting, as these cross-sections may be any cross-section that allows for the function described above, including but not limited to, circle tubular, oval tubular, triangle tubular, square tubular, pentagon tubular, hexagon tubular, heptagon tubular, and octagon tubular.

[0051] Figure 5A illustrates an outer portion of an electric machine housing. Figure 5B illustrates an inner portion of an electric machine housing. It should be noted that the housings described herein can be couped to a stator structurally and fluidically. The electric machine housings described herein may be made from materials with good thermal conductivity, such as aluminum, copper, an alloy thereof, or other metals or conductive polymers, to enable the housing to act as a heat exchanger. Referring to Figures 5A and 5B, a portion of an electric machine housing 500 can include a plurality of cooling fins 502 with internal conformal cooling channels (not illustrated in these Figures). Although not illustrated, each portion of an electric machine housing 500 may also include one or more stator fluid housing openings providing one or more fluid inlets or outlets to the fluidic channel/internal conformal cooling channels and be fluidically coupled to one or more coil winding of an array of coil windings of a stator.

[0052] Figure 6A illustrates an electric machine housing. Figure 6B a neutron radiograph of an internal channel in an electric machine housing. Figure 6C and 6D illustrate views of internal channels of positioned in cooling fins of an electric machine housing. Referring to Figure 6A, an electric machine housing 600 can be formed around an outer circumference of an array of coil windings of a stator (not illustrated in these Figures).

[0053] Referring to Figures 6A-6D, the electric machine housing 600 can include a fluidic channel 602 (e.g., as illustrated in Figures 6B-6D), a first stator housing fluid opening 604 providing a first fluid inlet or outlet to the fluidic channel 602 of the housing 600, and a second stator housing fluid opening 606 providing a second fluid inlet or outlet to the fluidic channel 602 of the housing 600. The first stator housing fluid opening 604 is fluidically coupled to one coil winding of the array of coil windings and the second stator housing fluid opening 606 opening is fluidically coupled to one coil winding of the array of coil windings.

[0054] In some cases, the one coil winding of the array of coil windings to which the second stator housing fluid opening 606 is fluidically coupled is a different coil winding than the one coil winding of the array of coil windings to which the first stator housing fluid opening 604 is fluidically coupled. In some cases, the housing 600 further includes one or more third stator housing fluid openings 608 providing one or more third fluid inlets or outlets to the fluidic channel of the housing. In some cases, the one or more third stator housing fluid openings 608 fluidically coupled to a middle location of one or more coil windings of the array of coil windings, as is further described with respect to Figures 8A and 8B).

[0055] Referring to Figures 6C and 6D, a portion of a housing 600 includes the fluidic channel 602 as internal conformal cooling channels located within a plurality of cooling fins 610.

[0056] Figure 7 illustrates unidirectional flow stator coil windings coupled to an electric machine housing with a plurality of cooling fins. Referring to Figure 7, three unidirectional flow stator coils 700, 702, 704 are positioned within an inner portion of an electric machine housing 706. Dielectric fluid can flow from a dielectric fluid distribution manifold 708 to the first unidirectional flow stator coil 700 via a first dielectric hose 710, through the first unidirectional flow stator coil 700, to the second unidirectional flow stator coil 702 via a second dielectric hose 712, through the second unidirectional flow stator coil 702 to the third unidirectional flow stator coil 704 via a third dielectric hose 714, and into the electric machine housing 706 via a fourth dielectric hose 716.

[0057] Figure 8A illustrates a side angled view of an array of coil windings coupled to an electric machine housing. Figure 8B illustrates a side angled view of an electric machine housing. Referring to Figures 8A and 8B, an array of coil windings 800 is coupled (e.g., structurally and fluidically) to an electric machine housing 810. The array of coil windings 800 are bidirectional flow coil windings, however, other embodiments could include unidirectional flow coil windings. As such, the array of coil windings 800 can include any features described herein with respect to bidirectional flow coil windings and/or unidirectional flow coil windings.

[0058] The electric machine housing 810 includes connections 812 and 814 to an external heat exchanger. Connections 812 and 814 may serve as inflow or outflow connections to the external heat exchanger depending on the desired mode of operation of the electric machine. The electric machine housing 810 further includes a plurality of fluidic channels 816 (which may be considered a single fluidic channel). The electric machine housing 810 further includes, for each coil winding of the array of coil windings 800, a first stator housing fluid opening 818 providing a first fluid inlet or outlet to the fluidic channels 816 of the housing 810 (with the first stator housing fluid opening 818 fluidically coupled to one coil winding of the array of coil windings via a first stator fluid opening), a second stator housing fluid opening 820 providing a second fluid inlet or outlet to the fluidic channels 816 of the housing 810 (with the second stator housing fluid opening 820 fluidically coupled to one coil winding of the array of coil windings 800 via a second stator fluid opening), and a third stator housing fluid opening 822 providing one or more third fluid inlets or outlets to the fluidic channels 816 of the housing 810 (with the third stator housing fluid opening 822 fluidically coupled to a middle location of one or more coil windings of the array of coil windings 800 via a third stator fluid opening).

[0059] In this embodiment, the first, second, and third stator housing fluid openings 818, 820, 822 are all fluidically coupled to a corresponding coil winding of the array of coil windings 800. In some cases, two of the stator housing fluid openings (e.g., the first and the second stator housing fluid openings 818, 820) are fluidically coupled to a corresponding coil winding of the array of coil windings 800 (e.g., in the case of unidirectional flow coil windings). In some cases, only one of the stator housing fluid openings (e.g., the third stator housing fluid opening 822) is fluidically coupled to a corresponding coil winding of the array of coil windings 800. This allows for every coil windings of the array of coil windings 800 to be fluidically coupled with the electric machine housing 810 via a stator housing fluid opening.

[0060] Figure 9A illustrates a stator coupled to an electric machine housing having a coolant distribution manifold. Figures 9B illustrates a coolant distribution manifold. Figure 9C illustrate internal channels in a coolant distribution manifold. Referring to Figure 9A, a first dielectric fluid distribution manifold 900 is coupled (e.g., structurally and fluidically) to a first flat end 902 of an electric machine housing 904 and a second dielectric fluid distribution manifold 910 is coupled (e.g., structurally and fluidically) to a second flat end (not illustrated) of the electric machine housing 904. A stator having an array of coil windings 906 is coupled (e.g., structurally and fluidically) to the electric machine housing 904. In some cases, the first dielectric fluid distribution manifold 900 and the second dielectric fluid distribution manifold 910 are fluidically coupled to an external heat exchanger and/or pump to move/circulate the dielectric fluid therethrough via a manifold outlet 912 (e.g., one manifold outlet 912 for each dielectric fluid distribution manifold). Referring to Figure 9C, each dielectric fluid distribution manifold 900, 910 includes internal fluidic channels 914 to move fluid to and/or from the electric machine housing 904.

[0061] Depending on the design choices such as the number of stator housing fluid openings (e.g., such as stator housing fluid opening 718), the number of stator fluid openings, flow rate, pump sizing, bidirectional flow coils or unidirectional flow coils, torque and power density requirements as well as the associated heat dissipation needed to meet the torque and power density requirements, and/or other variables known to those familiar with design of electric machines, 1) every coil winding of an array of coil windings can be connected to an electric machine housing and/or dielectric fluid distribution manifold; 2) every other coil winding of an array of coil windings can be connected to an electric machine housing and/or dielectric fluid distribution manifold; 3) every third coil winding of an array of coil windings can be connected to an electric machine housing and/or dielectric fluid distribution manifold; 4) only one or two coil windings of an array of coil windings can be connected to an electric machine housing and/or dielectric fluid distribution manifold. Other coil windings of an array of coil windings can be connected to one another as illustrated between stator coils 700, 702 of Figure 7 and stator coils 702, 704 of Figure 7 and/or connected to an external heat exchanger (e.g., radiator). Any of these connections can be made, for example, using any of the devices (e.g., stator fluid opening, stator housing fluid opening, dielectric hose, etc.) described herein and/or known to those to those familiar with design of electric machines.

[0062] Furthermore, in various implementations, there can be any number of coil windings connected to an electric machine housing, dielectric fluid distribution manifold, external heat exchanger, and/or pump; and any number of coil windings connected to each other in order to connect to a coil winding that is connected to the electric machine housing, dielectric fluid distribution manifold, external heat exchanger, and/or pump. .

[0063] In some cases, an array of coil windings of a stator as described herein can be structurally coupled to a structural housing (e.g., with no fluidic coupling). In these cases, the array of coil windings may be coupled with an external heat exchanger. In some of these cases, a dielectric fluid distribution manifold may be included.

[0064] The complex internal geometry of the array of coil windings, housing, and/or dielectric fluid manifold may be challenging to manufacture using conventional means. Therefore, additive manufacturing methods, such as laser powder fusion and binder jetting. In certain embodiments, manufacture of such systems could be made using a cast process, for example a lost wax process. However, such processes are more complex, may not yield a final product having the same level of internal detail, and can leave residue that is difficult to fully remove after production is complete. However, such processes may be useful in the context of a corpus of electric machine housings that are produced by additive manufacturing, for example to match the footprint and interface of a common group of machines, where production via casting or other methods would not be commercially viable in the abstract, but are viable in the specific context.

[0065] In some cases, a bidirectional flow coil winding can be manufactured by, for example, manufacturing two smaller unidirectional coil windings and stacking them on one another. Depending on the type of the third stator fluid opening being used (e.g., with or without a divider wall), a bidirectional flow coil winding may need further modifying beyond stacking two smaller unidirectional coil windings. In any case, additive manufacturing can be used to manufacture unidirectional flow coil windings and bidirectional flow coil windings.

[0066] Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

Claims

CLAIMS What is claimed is:

1. An electric machine comprising: a rotor; and a stator comprising an array of coil windings, wherein each coil winding comprises a tubular body configured to allow dielectric fluid to move therethrough.

2. The electric machine of claim 1 , further comprising a housing formed around an outer circumference of the array of coil windings of the stator, wherein the housing comprises: a fluidic channel; a first stator housing fluid opening providing a first fluid inlet or outlet to the fluidic channel of the housing, the first stator housing fluid opening fluidically coupled to one coil winding of the array of coil windings; and a second stator housing fluid opening providing a second fluid inlet or outlet to the fluidic channel of the housing, the second stator housing fluid opening fluidically coupled to one coil winding of the array of coil windings.

3. The electric machine of claim 2, wherein the one coil winding of the array of coil windings to which the second stator housing fluid opening is fluidically coupled is a different coil winding than the one coil winding of the array of coil windings to which the first stator housing fluid opening is fluidically coupled.

4. The electric machine of claim 2, wherein the housing further comprises one or more third stator housing fluid openings providing one or more third fluid inlets or outlets to the fluidic channel of the housing, the one or more third stator housing fluid openings fluidically coupled to a middle location of one or more coil windings of the array of coil windings.

5. The electric machine of claim 4, wherein at least one of the first, second, and third stator housing fluid openings are fluidically coupled to at least every third coil winding of the array of coil windings.

6. The electric machine of claim 4, wherein at least one of the first, second, and third stator housing fluid openings are fluidically coupled to every coil winding of the array of coil windings.

7. The electric machine of claim 2, wherein the fluidic channel of the housing comprises internal conformal cooling channels located within a plurality of cooling fins.

8. The electric machine of claim 2, further comprising: a first dielectric fluid distribution manifold coupled to a first flat end of the housing; and a second dielectric fluid distribution manifold coupled to a second flat end of the housing, wherein the first dielectric fluid distribution manifold and the second dielectric fluid distribution manifold are fluidically coupled to an external heat exchanger or pump to move the dielectric fluid therethrough.

9. The electric machine of claim 1 , further comprising a pump configured to circulate the dielectric fluid through each of the array of coil windings of the stator.

10. The electric machine of claim 1, wherein each coil winding further comprises: a first stator fluid opening providing a first fluid inlet or outlet, the first stator fluid opening at a top end the tubular body; a second stator fluid opening providing a second fluid inlet or outlet, the second stator fluid opening at a bottom end of the tubular body; and a third stator fluid opening providing a third fluid inlet or outlet, the third stator fluid opening at a middle location of the tubular body, whereby dielectric fluid is able to move from the first stator fluid opening, through the top end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on a pump operation; and whereby dielectric fluid is able to move from the second stator fluid opening, through the bottom end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on the pump operation.

11. The electric machine of claim 10, wherein the third stator fluid opening of each coil winding comprises an interior dividing wall such that dielectric fluid moving from first stator fluid opening to the middle location of the tubular body does not come into contact with dielectric fluid moving from the second stator fluid opening to the middle location of the tubular body within a corresponding coil winding.

12. The electric machine of claim 10, wherein the third stator fluid opening of each coil winding allows for dielectric fluid moving from the first stator fluid opening to the middle location of the tubular body to contact with dielectric fluid moving from the second stator fluid opening to the middle location of the tubular body.

13. A stator for an electric machine, comprising: an array of coil windings, wherein each coil winding comprises a tubular body configured to allow dielectric fluid to move therethrough.

14. The stator of claim 13, wherein each coil winding of the array of coil windings further comprises: a first stator fluid opening providing a first fluid inlet or outlet, the first stator fluid opening at a top end the tubular body; and a second stator fluid opening providing a second fluid inlet or outlet, the second stator fluid opening at a bottom end of the tubular body.

15. The stator of claim 14, wherein each coil winding of the array of coil windings further comprises: a third stator fluid opening providing a third fluid inlet or outlet, the third stator fluid opening at a middle location of the tubular body, whereby dielectric fluid is able to move from the first stator fluid opening, through the top end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on a pump operation; and dielectric fluid is able to move from the second stator fluid opening, through the bottom end of the tubular body to the middle location of the tubular body, and out the third stator fluid opening and vice versa depending on the pump operation.