JP2003507994A - Water-cooled stator winding of electric motor - Google Patents

Abstract

(57) Abstract: The present invention relates to a cooling device for cooling a stator (200) having a winding (1). The windings, including the cooling members (14, 17, 101, 102), are electrically separated from each other and are thermally connected to the outer surface of the windings. The cooling member has at least one passage therethrough to receive cooling fluid from an external source. Water containing ions (e.g., water) can be used as a coolant to cool the stator because the passage receiving the coolant is insulated from the high voltage stator conductors. Allowing the use of water has significant advantages in configurations where deionized water is not readily available and reduces the cost of the water deionization system.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION The present invention relates to cooling stators of electric motors. Electric machines, such as motors and generators, generate heat in the windings during use and therefore generally require cooling to operate optimally and avoid damage to the components.

Many electric machines have a rotor assembly surrounded by stator windings, which are cooled by passing a cooling fluid through passages formed in the stator winding conductors themselves. For example, cooling water is typically supplied through passages in the conductors of the stator to remove heat from the stator. After that, the hot water
It is cooled by a heat exchanger before it is reused in the stator.

In certain applications, cooling with impure fluids (ie, those that have ions such as water) that can electrolyze to deposit solid materials and clog passages can be Disturbed by the high electric field of. In addition, impurities in the fluid may ionize and conduct inappropriate currents.

Therefore, in the conventional stator cooling system, more expensive deionized water is used instead of natural water (water). Providing deionized water generally requires that the processor maintain water purity and resistivity.

SUMMARY OF THE INVENTION The present invention is directed to a cooling device for cooling a stator having windings that are electrically isolated from each other. In a general aspect of the invention, a cooling device includes a cooling member that is thermally connected to an outer surface of a winding and that has at least one passage extending therein for receiving coolant from an external source.

Since the passages that receive the coolant do not extend inside the conductors of the stator, but inside the cooling means, it is possible to use water as a coolant for cooling the stator. . The cooling means is thermally connected to the stator winding via an electrically insulated grounded wall. Allowing the use of water has significant advantages when deionized water is not readily available or the user does not want to incur the cost of a water deionization system. For example, a ship having an electric motor with a stator that is cooled in a conventional manner requires the storage of deionized water for cooling. The externally cooled arrangement of the present invention eliminates this need.

Embodiments of the invention may have one or more of the following features. For example, in one embodiment of the invention the cooling member comprises at least one spirally wound tube defining a passage. For example, in a stator having a hollow inner surface and an outer surface, a spirally wound tube is thermally connected to the hollow inner surface and a second spirally wound tube is thermally connected to the outer surface of the stator. Connected.

In certain embodiments, the stator may be constructed such that the stator windings are radially spaced from the longitudinal axis of the stator and circumferentially spaced from one another. The alternating windings further have end regions that extend radially distal from the axis. This structure can be used to provide a three-phase stator winding assembly.
In this application, the cooling member further comprises a spirally wound tube in the end region of the stator winding. The spirally wound tube is thermally connected to the radially expanding end region. The spirally wound tube may be formed from a non-magnetic material such as aluminum or stainless steel.

In another embodiment of the present invention, the cooling member has a laminated heat conducting member, and each individual conducting member has a hole. The heat-conducting member is provided such that the holes generally define passages. The individual conducting members reduce eddy currents, preferably by being electrically isolated from adjacent conducting members. Eddy currents can significantly increase heating of the component. Electrical isolation is provided by providing an insulating material between the conductive members and corresponding outer surfaces on adjacent windings of the stator.

The individual conductive members have a radially extending portion provided between the outer surfaces of adjacent windings of the stator and thermally connected thereto. The radially expanding portion provides greater contact between the faces between the conductive member and the winding.

In a particular embodiment, each winding is wound on a first axis and the cooling member is of a tube spirally wound about a second axis orthogonal to the first axis. Make a shape. Alternatively, the cooling member is in the form of a tube that is coaxially wound around the first axis. In this case, a first cooling member is provided on the upper surface of the winding, and a second cooling member in the form of a tube that is coaxially wound around the first axis is provided on the lower surface of the winding. The coaxially wound tube has a racetrack shape and may be a saddle shape.

Other advantages and features of the invention will be apparent from the following description and claims. (Detailed Description) Referring to FIG. The three-phase stator 1 has multi-phase coil assemblies 8 to 13,
They are arranged as the inner layers 11, 12, 13 of the phase coil assembly and the outer layers 8, 9, 10 of the phase coil assembly. Outer layer coil assembly 8, 9
, 10 have end regions 8a, 9a, 10a that extend away from the corresponding end regions of the adjacent internal phase coils. Each phase coil assembly has concentric coil windings 7 which are insulated from each other. Although the end regions 8a, 9a, 10a of the outer layer coil assemblies 8, 9, 10 are exaggerated in FIG. 1, they are not normally perpendicular to the central axis of the stator (see FIG. 3). As described in more detail below, the present invention is directed here to a cooling system that minimizes the exposure of water coolant to high voltages in the stator coils. This allows the use of water with ions.

The individual phase coil windings are formed of any electrically conductive material, such as copper, aluminum or the like. Typically, the phase coil is made of copper. The phase coil assembly can be formed using different methods.

For example, each phase coil assembly in the embodiment shown in FIG.
It has a number of concentric coil windings, each insulated. Typically,
Each phase coil assembly can consist of any number of concentric coil windings, depending on the stator motor design. Further, each concentric coil winding can consist of a respective insulated and integrally assembled coil to form the concentric coil winding. Each coil may be insulated to withstand the voltage between the coils and assembled to form concentric coil windings. Each concentric coil winding is then assembled to form a phase coil assembly. The assembly is well isolated with respect to phase-to-phase and phase-to-ground voltage levels.

In another method, the conductor is coaxially wound with a suitable per rotation insulator to form a phase coil assembly. The completed phase coil assembly is well isolated with respect to phase-phase and phase-ground voltage levels. In order to reduce eddy current losses in these coils, preferably any fully transposed Litz wire is generally used. In certain applications, Rutherford type conductors are used. Rutherford-type conductors consist of a large number of smaller strands that are sufficiently displaced to separate the AC electric field that conductors at arbitrary locations are exposed to. Rutherford Conductor
The flexibility makes the coil forming work easier. All phase coil assemblies are insulated to an industrially acceptable insulation class (eg Class H and F insulation). This insulation class usually determines the maximum temperature at which the conductor can operate. Similarly, Rutherford-type conductors are readily available from a number of sources including New England Electric, Lisbon, NH.

Please refer to FIG. The cooled stator system 100 has a central hole 2 in the stator.
The inner coil 14 of the stator, the outer coil 17 surrounded by the outer surface of the stator 1, and the end coil 101 wound around the ends 103 and 104 of the stator.
, 102. The outer coil 17 includes end portions 117, 119 that surround the outer layers 105, 106 of the phase coil assemblies 8, 9, 10 and a central portion 120 that surrounds the middle portion 107 of the inner layers of all the phase coil assemblies 8-13. Have and. Each of the inner coil 14, the outer coil 17, and the end coils 101 and 102 is
It is in fluid communication with the inlets 15, 18, 110, 11 and the outlets 16, 19, 111, 113, respectively.

As shown in FIG. 3, the cooled stator system 200 has a phase coil 1 surrounded by a non-metallic hollow tube 162 having an axis L. Cooling tubes 14, 10
1, 102 and 17 are wound around the phase coil 1 and housed in the core 160. The core 160 is typically about 0.05 cm (0.02 inch), an iron core comprised of a thick iron laminate structure such as those used in the automotive industry. The laminar structure is cut into circular pieces and assembled around the stator assembly 200.
As an alternative, the core 160 is formed by winding an iron wire having a high magnetic permeability. The core 160 is insulated by a varnish or an oxide to suppress eddy current heating. It is possible to sufficiently wrap this layer of wire to form the flat cylindrical outer surface 170 shown in FIG.

The cooled stator system 200 is inserted inside the motor housing.
The entire assembly, including the stator and motor housing, is impregnated with epoxy resin and all components of the stator are glued together to form a unitary structure. The inner coil 14 is supported inside the stator 1 by a hollow tube 162. Inner coil 14, outer coil 1
7, and the end coils 101, 102 are electrically separated from the stator 1 by an insulator 150. The insulator 150 maintains the coils 14, 17, 101, 102 at ground potential, thus allowing the use of water with ions. The insulator 150 is
It is formed from any insulating material that can withstand the operating voltage and the heat generated by the stator 1. Insulator 150 is generally thick enough to withstand operating voltages. The thickness of the insulator 150 is determined by the dielectric strength (insulating property) of the material. For example, the thickness of an insulating material having a high dielectric strength may be less than the thickness of an insulating material having a low dielectric strength. Typically, the insulator 150 is about 0.0
It has a thickness between about 025 cm and 0.25 cm (about 0.001 to 0.100 inch). Examples of insulating materials include, but are not limited to, epoxy resin, mica, and glass.

In operation, heat is conducted from the conductors of the stator through the insulator 150 to the coils 14, 17, 101, 102 with cooled water. Exits 16, 19,
By having a higher fluid pressure at the inlets 15, 18, 110, 112 than at 111, 113, the cooling fluid flows inside the coils 14, 17, 101, 102. Therefore, the heat conducted to the water is removed from the cooled stator system. In order to improve the cooling of the stator 1, the inner coil 14 removes heat from the inside and the other outer coil 17 and the end coils 101, 102 remove heat from the outside. FIG. 3A shows the phase coils 8-13 surrounded by a cooling tube 17.

Please refer to FIG. In another embodiment, as shown in FIG. 1, the cooled stator system 200 has the stator 1 surrounded by a heat conductive material 24. The heat-conducting material 27, 37 is provided around the intermediate portion 107 of the stator 1 in a series of plate 21
Are formed by stacking. Phase coils 8, 9, 10, 11, 12, 13
Are assembled around the hollow tube 162 such that they contact each other at the hollow tube surface.
However, the sides of the coil are separated from each other on the outer surface of the coil assembly 7. This gap is filled with a wedge-shaped portion 37 (here aluminum) of the plate 21 as shown in FIG. The aluminum wedge 37 facilitates the removal of heat from the coil side 7. In particular applications, aluminum wedges 37 are formed in a laminated structure to reduce eddy current losses. These laminated structures are
It further has a hole 25 used for passage of cooling water. Each phase coil (8-13)
These wedge-shaped parts are provided in, and the phase coil assembly is impregnated with epoxy resin,
It is also possible to test electrically and thermally before assembling it into the stator assembly. When all the phase assemblies are assembled, the stator coil assembly with cooling wedges forms the assembly 12 shown in FIG.

The plate 21 is made of a heat conductive material. Examples of heat conductive materials are metals such as copper, iron, aluminum and UCAR International of Nashville, TN.
Inc. ), A flexible graphite material such as Grafoil®. Grafoil® is about 100% copper.
While having double the electrical resistance properties, it advantageously has a thermal conductivity similar to that of copper. Typically, the plate is made of a non-magnetic material such as copper or aluminum. Each plate 21 has a main part 320 and a wedge-shaped part 37 extending in the radial direction toward the central axis of the stator. Typically, the ends 10 of the stator are arranged such that the passages 25 from each plate form an external hollow 29 for mounting cooling tubes.
The plate 21 is aligned between 3, 104. The outer hollow 29 has a central axis (L
A) and provides a passageway for the water flow path. Each plate 21 can also be isolated from adjacent plates to reduce eddy currents that increase heating.

FIG. 5 is a plan view of the plate 21 including the coil 306, the main portion 320, and the tooth portion 37 of the stator 1. Each plate may have passages 25 radially arranged at equal intervals around the stator middle portion 107. For example,
Each plate 21 may have a passage for each winding of the stator. As shown in more detail in FIG. 6, the coil 306 has adjacent windings 6, 7 having an inner end 32 and an outer end 34. The teeth 37 are packed between adjacent windings so that the windings make contact at the inner end 32, the hollow side, and are spaced at the outer end 34. The inner body 37 provides additional surface area for heat transfer between the windings and the coolant manifold.

In an alternative embodiment, fluid may be transferred from one passage to another to form a continuous fluid flow loop. For example, in FIG. 6, passage 25 may be connected to passage 36 so that fluid passes from passage 25 to passage 36 before it exits the cooling system. In other embodiments, the hot water from the cooling system may be cooled by passing it through a heat exchanger before reinjecting it into the system. Alternatively, the water to the cooling system can be drawn from the main source of water and discarded after use.

In yet another embodiment, the stator winding assembly is cooled using a stator cooling system having a morphology similar to the stator windings themselves. For example, please refer to FIGS. A type of stator winding 400 similar to the phase coil assemblies 11, 12, 13 of the three-phase stator 1 (see FIG. 1) is shown independent of its adjacent phase coil assembly. In this embodiment, the cooling system 41
0 is concentrically wound around the shaft 415 of the stator winding 400 and
00 has a pair of cooling pipes 412 and 414 arranged on the opposite side. Incidentally, the shaft 415
Is orthogonal to the axis L of the embodiment of the cooled stator system 200 shown in FIG. More specifically, cooling tubes 412 are arranged in thermal contact with the inner and outer surfaces of stator winding 400, respectively.

As in the case of the cooling pipes described above, the cooling pipes 412 and 414 are formed of a non-magnetic material such as aluminum or stainless steel. Due to its corrosion resistance and low eddy current loss characteristics, stainless steel is suitable for many applications.

Unlike the embodiments described in connection with FIGS. 1-6, the cooling tubes 412, 414 are
It is coaxially wound in a saddle-shaped racetrack shape similar to the stator winding 400. As shown in FIG. 8, the cooling tubes are wound to conform to the generally curved surface of the stator windings and are wound in a bifilar fashion.

By “bifilar” is meant that the cooling tubes of two lengths are wound in parallel (closely wound) with one above the other. This allows
Each cooling pipe 412, 414 has an inlet 416, 4 that extends from the outer periphery of the cooling pipe.
18 and a helical structure with outlets 420, 422. Winding a cooling tube using a bifilar method advantageously places the inlet and outlet next to each other without the need for a length of tube extending backwards across the wound cooling tube. To be able to be done. Furthermore, the cooling tube itself couples to the magnetic flux from the magnetic field of the stator windings, forming a coil that cools the stator windings. The bifilar method reduces eddy current loss by reducing the voltage and circulating current flowing through the cooling tube.

One approach to winding the cooling tubes 412, 414 in a bifilar fashion is to have a fixed length of the cooling tube at its midpoint to form a U-shaped bend 424 (FIG. 7). Can be folded on itself. After that, the folded length of the cooling pipe is directed to the outside and is coaxially wound so that one of the cooling pipes is folded back.

In a multi-phase stator having multiple stator windings (eg, the three-phase stator assembly of FIG. 1), the cooling tubes 412, 414 of the cooling system 410 are individually housed in each of the stator windings. Provide a subsystem that can be tested separately and independently.

[Brief description of drawings]

FIG. 1 is a perspective view showing a single-layer three-phase stator having a coil winding.

2 is an exploded perspective view of the stator of FIG. 1 including an external spiral cooling tube.

FIG. 3 is a cross-sectional view schematically showing the stator and the cooling pipe of FIG.

FIG. 3A is a perspective view showing a partial assembly of stator coils with cooling tubes.

FIG. 4 is a cross-sectional view of an alternative embodiment stator cooling system.

5 is a cross-sectional view taken along the plane AA of FIG. 4 showing the end of the cooling system.

6 is an enlarged view of part A of the cooling system of FIG.

FIG. 7 is a perspective view of an alternative embodiment of a coil winding stator cooling system.

8 is a perspective view showing a cross section of the stator cooling system of FIG. 7.

9 is an end view of the stator cooling system of FIG. 7.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, C A, CH, CN, CR, CU, CZ, DE, DK, DM , DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, K E, KG, KP, KR, KZ, LC, LK, LR, LS , LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, SL, TJ, TM , TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Snitchler, Gregory El.             United States 01545 Massachusetts             Shrewsbury Ireta Road, Tutu               64 (72) Inventor Gumble, Bruce Bee.             United States 02482 Massachusetts             Wellesley Pinewood Law             Do 14 (72) Inventor Bushko, Darewz Antoni             United States 01748 Massachusetts             Hopkinton Lamp Lighter             4 F-term (reference) 5H603 AA13 BB01 BB07 BB12 CA01                       CA05 CB02 CB03 CB23 CB26                       CC01 CC18 CD04 CD11 CD21                       CE13 EE12                 5H609 PP02 PP06 PP09 QQ04 QQ12                       RR37 RR40 RR46 RR53 RR69                       RR73 RR74 SS03

Claims (18)

[Claims] 1. A stator cooling device having a plurality of windings, each winding electrically insulated from other windings, the device comprising a cooling member thermally connected to an outer surface of the winding. The cooling member has at least one passage extending therein for receiving a coolant from an external source. 2. The apparatus of claim 1, wherein the cooling member comprises at least one spirally wound tube defining the at least one passage. 3. The winding of the stator is formed so as to define a hollow inner surface and an outer surface, and the cooling member has a plurality of spirally wound tubes, and the spirally wound tubes. The apparatus of claim 2 wherein a first tube of the two is thermally connected to the hollow inner surface and a second tube of the second tube is thermally connected to the outer surface. 4. The ends of the stator windings radially spaced from the longitudinal axis of the stator and circumferentially spaced from one another, the windings alternatingly extending distally radially from the axis. The apparatus of claim 3 having a region, wherein the cooling member comprises a spirally wound tube having an end region thermally connected to the radially expanding end region. . 5. The apparatus of claim 1 wherein each of said phase coils comprises a single conductor wound coaxially. 6. The apparatus of claim 1, wherein each of the phase coils comprises a plurality of coaxially wound coils. 7. The device of claim 3, wherein the plurality of spirally wound tubes are formed from a non-magnetic material. 8. The apparatus according to claim 1, wherein the cooling member is composed of a plurality of heat-conducting members having a multi-layered structure, and each of the heat-conducting members has a hole forming the at least one passage as a whole. 9. The device of claim 8 wherein each conductive member is electrically isolated from an adjacent conductive member. 10. The apparatus according to claim 9, further comprising an insulating material provided between the conductive member and a corresponding outer surface of an adjacent winding of the stator. 11. The apparatus of claim 8 wherein each conductive member has a radially extending portion disposed between the outer surfaces of adjacent windings of the stator and thermally connected to the outer surface. . 12. The heat conductive member is formed of a non-magnetic material.
The device according to. 13. Each winding is wound on a first shaft and the cooling member is
3. The device of claim 2 in the form of a tube helically wound about a second axis orthogonal to the first axis. 14. The apparatus of claim 2 wherein each winding is wound on a first axis and the cooling member is in the form of a tube coaxially wound about the first axis. 15. The cooling member is provided on an upper surface of the winding, and the device has a second cooling member in the shape of a tube coaxially wound around the first axis, The device according to claim 14, wherein the second cooling member is provided on a lower surface of the winding. 16. The apparatus of claim 14, wherein the coaxially wound tube has a racetrack shape. 17. The coaxially wound tube has a saddle shape.
The device according to. 18. The device of claim 15, wherein the coaxially wound tube is formed of a non-magnetic material.