ROTOR SYSTEM FOR PERMANENT MAGNET MOTORS POWERING ELECTRIC SUBMERSIBLE PUMPS

Abstract

Embodiments disclosed herein describe methods for improved permanent magnet motor rotor systems for submersible electric motors. The improved rotor system includes a single piece of material shaft with surface mounted permanent magnets. The single piece of material shaft minimizes the number of shaft bearings and locates the bearings outside of the stator windings.

Claims

1. An electrical submersible pump powered by a permanent magnet motor comprising a shaft, bearings, and a stator, wherein the shaft comprises a first rotor system.

2. The electrical submersible pump of claim 1, wherein the first rotor system comprises a plurality of permanent magnets positioned between an upper bearing and a lower bearing.

3. The electrical submersible pump of claim 2, further comprising a housing encompassing the stator and coupled to a head and base of the first rotor system proximate to the upper bearing and lower bearing, respectively.

4. The electrical submersible pump of claim 2, wherein the shaft has a proximal end that extends past the upper bearing and/or a distal end that extends past the lower bearing to allow an attachment of one or more additional rotor systems in series.

5. The electrical submersible pump of claim 4, wherein each of the one or more additional rotor systems comprises a plurality of additional permanent magnets positioned between an additional upper bearing and an additional lower bearing.

6. The electrical submersible pump of claim 4, wherein: the upper bearings are positioned between: the proximal end of the permanent magnet rotor system and the stator; and the proximal end of the shaft; and the lower bearings are positioned between: the distal end of the at least one permanent magnet rotor system and the stator; and the distal end of the shaft.

7. The electrical submersible pump of claim 4, wherein the attachment of the first rotor system to the one or more additional rotor systems in series transfers torque across the first rotor system and the one or more additional rotor systems.

8. The electrical submersible pump of claim 2, wherein: the shaft has depressions extending from an outer circumference of the shaft towards a central axis of the shaft; and the plurality of permanent magnets are positioned within the depressions.

9. The electrical submersible pump of claim 8, wherein each of the plurality of permanent magnets have a shape that corresponds to the shape of each of the depressions.

10. The electrical submersible pump of claim 9, wherein the stator comprises stacked laminations and copper windings, and the stacked laminations are positioned around the depressions embedded with the permanent magnets,

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0015] FIG. 1 depicts a permanent magnet motor rotor system, according to an embodiment.

[0016] FIG. 2 depicts a horizontal cross section of permanent magnet motor system, according to an embodiment.

[0017] FIG. 3 depicts a longitudinal cross section of a permanent magnet motor system, according to an embodiment.

[0018] FIG. 4 depicts a method for forming a permanent magnet motor, according to an embodiment.

[0019] Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure.

DETAILED DESCRIPTION

[0020] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present embodiments. It will be apparent, however, to one having ordinary skill in the art, that the specific detail need not be employed to practice the present embodiments. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present embodiments.

[0021] FIG. 1 depicts a permanent magnet motor rotor system 100, according to an embodiment. Permanent magnet motor rotor system 100 may include a shaft 110, upper bearings location 120, lower bearings location 130, depressions 140, and permanent magnets of a first polarity 150 and of a second polarity 160.

[0022] Shaft 110 may be a rotor that is a moving component of permanent magnet rotor system 100. Shaft 110 may include a proximal end 112 that extends past upper bearings location 120, and a distal end 114 that extends past lower bearings location 130. Proximal end 112 and distal end 114 may be configured to allow an attachment of a load or additional permanent magnet rotor systems 100 in series. By coupling a plurality of permanent magnet rotor systems 100 in series, torque across the multiple systems may be transferred to each other, such that the power of the plurality of permanent magnet rotor systems 100 may be customized and amplified.

[0023] Upper bearings location 120 may be positioned between proximal end 112 of shaft 110 and a first end 142 of depressions 140. Upper bearings location 120 may be a location where upper bearings are positioned, wherein the upper bearings are configured to reduce rotational friction while supporting radial and axial loads. Lower bearings location 30 maybe positioned between a second end 144 of depressions 140 and distal end 114 of shaft 110. Lower bearings location 130 may be a location where lower bearings are positioned, wherein the lower bearings are configured to reduce rotational friction while supporting radial and axial loads. The positioning the bearings 4 between the ends 112, 114 of the shaft 110 and the ends 142, 144 of the depressions 140 allow for the bearings to be positioned in a lower temperature environment. Furthermore, the location of the bearings outside of permanent magnets 150, 160 allow for no bearings 1 to be positioned inside of the stator, and the bearings to be positioned outside of all the stator copper windings.

[0024] Depressions 140 may be grooves, indentations, machined depressions, millings, etc. positioned on an outer circumference of shaft 110, at a location between upper bearings 120 and lower bearings 130. Depressions 140 may extend from the outer circumference of shaft 110 and extend towards a central axis of shaft 110, wherein depressions 140 decrease a diameter across shaft 110 at locations that correspond with depressions 140. The depressions 140 allow for more magnet material to be placed within shaft 110. Shaft 110 may include a plurality of depressions 140, which may include any number of depressions 140. In embodiments, the depressions 140 may be spaced apart by channels 146, which may have a shorter width than that of depressions 140.

[0025] Permanent magnets 150, 160 may be materials where a magnetic field is generated by the internal structure of the material itself. Permanent magnets 150, 160 may include north magnet stacks 150 and south magnet stacks 160, with the same or different number of north magnet stacks 150 and south magnet stacks 160. In embodiments, the permanent magnets 150, 160 may have a shape that corresponds with a shape of depressions 140, such that the permanent magnets 150, 160 may be surface mounted within the depressions 140. When permanent magnets 150, 160 are positioned within depressions 140, the outer circumferences of the permanent magnets 150, 160 may correspond to the outer circumference of channels 146 to form uniform outer circumference. The positioning of the permanent magnets 150, 160 allows the permanent magnet rotor system 100 to locate the permanent magnets 150, 160 between the bearings to increase the power density, performance, torque, and torsional rigidity of permanent magnet rotor system 100.

[0026] FIG. 2 depicts a horizontal cross section of a permanent magnet motor system 200, according to an embodiment. Elements depicted in FIG. 2 maybe described above, and for the sake of brevity a further description of these elements is omitted.

[0027] As depicted in FIG. 2, shaft 110 may include a plurality of north stack permanent magnets 150 and south stack permanent magnets 160 positioned in depressions 140. A plurality of stator copper windings 210 may be positioned in stacked laminations 220, which encompasses shaft 110. Stacked laminations 220 may be encompassed by a housing 230 that is configured to be coupled to a head and base of the permanent magnet motor system 200.

[0028] Because permanent magnets 150, 160 are embedded within machined depressions, the diameter of shaft 110 can be sufficiently equal and maximized at all locations. In other words, the outer diameter of shaft 110 is slightly smaller than the inner diameter of laminations, while an annulus or air gap between laminations 220 and the outer diameter of shaft 110 is substantially constant.

[0029] FIG. 3 depicts a longitudinal cross section of permanent magnet motor system 200, according to an embodiment. Elements depicted in FIG. 3 maybe described above, and for the sake of brevity a further description of these elements is omitted.

[0030] As depicted in FIG. 3, upper bearings 302 and lower bearings 304 are positioned outside of the stator copper windings 210. This may allow upper bearings and lower bearings 130 to be positioned within a lower temperature environment than within the stator.

[0031] As further shown in FIG. 3, housing 230 may be coupled to a head 310 and base 320 of the permanent magnet motor system 200.

[0032] FIG. 4 depicts a method 400 for forming a permanent magnet motor system 200, according to an embodiment. The operations of the method presented below are intended to be illustrative. In some embodiments, the method may be accomplished with one or more additional operations not described, and/or without one or more of the operations discussed. Additionally, the order in which the operations of the method are illustrated in FIG. 4 and described below is not intended to be limiting.

[0033] At operation 410, a plurality of depressions may be machined out of the outer diameter of a shaft towards a central axis of the shaft. In embodiments, a plurality of channels may be formed between the plurality of channels, wherein the channels have a larger diameter than that of the plurality of depressions.

[0034] At operation 420, a plurality of permanent magnets may be positioned into the milled depressions. The plurality of permanent magnets may be shaped such that the circumference of the shaft is substantially constant between locations with permanent magnets and channels formed between the machined depressions.

[0035] At operation 430, stator copper windings and stacked laminations may be positioned around the machined depressions embedded with the permanent magnets.

[0036] At operation 440, upper and lower bearings may be positioned outside of the stator copper windings.

[0037] Reference throughout this specification to one embodiment, an embodiment, one example or an example means that a particular feature, structure or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, appearances of the phrases in one embodiment, in an embodiment, one example or an example in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures or characteristics may be combined in any suitable combinations and/or sub-combinations in one or more embodiments or examples. In addition, it is appreciated that the figures provided herewith are for explanation purposes to persons ordinarily skilled in the art and that the drawings are not necessarily drawn to scale.

[0038] Although the present technology has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred implementations, it is to be understood that such detail is solely for that purpose and that the technology is not limited to the disclosed implementations, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present technology contemplates that, to the extent possible, one or more features of any implementation can be combined with one or more features of any other implementation.