Small-diameter high-speed submersible permanent magnet synchronous motor

Abstract

The invention belongs to the technical field of permanent magnet synchronous motors, and discloses a small-diameter high-speed submersible permanent magnet synchronous motor. Comprising a shell; the stator assembly is fixed in the casing and comprises a stator iron core fixedly connected with the casing and a stator winding embedded in the stator iron core; the rotor assembly is arranged in the cavity and is in running fit with the stator assembly; and the motor head and the tailstock are respectively fixed at the upper end and the lower end of the shell. The rotor assembly comprises a stepped motor shaft located in a cavity of the stator core, a plurality of rotor sections and a centralizing bearing, the stepped motor shaft comprises a bearing shaft and a leading-out shaft which are connected in sequence, the diameter of the bearing shaft is larger than that of the leading-out shaft, the leading-out shaft penetrates out of the motor head and is in running fit with the motor head, and the centralizing bearing and the rotor sections sleeve the bearing shaft at intervals; the rotor joints are in key connection with the bearing shaft. The small-diameter high-speed submersible permanent magnet synchronous motor provided by the invention solves the problems that the submersible permanent magnet synchronous motor is difficult to pass through a slim-hole well casing, the torsional deformation of the motor shaft is too large and the interference is caused during assembly.

Description

Technical Field

[0001] The invention relates to the technical field of permanent magnet synchronous motors, and in particular to a small-diameter high-speed submersible permanent magnet synchronous motor. Background Art

[0002] With the continuous deepening of oil field development, the cost of oil and gas exploration and development continues to rise. Slimhole wells have gradually become the development direction of current oil companies in deep wells, low-permeability oil fields, small oil reservoirs and redevelopment of old oil wells because of their low drilling cost and the characteristics of conventional drilling technology. Limited by the size of the production casing, the size of the submersible motor must be small enough to ensure smooth passage when going down the well. In the late stage of development, old oil wells enter the high water content production stage, requiring the submersible pump to have a larger displacement. For the same displacement, the centrifugal pump is more compact and smaller than the screw pump, and can better adapt to small-sized casings. However, driving the centrifugal pump requires the submersible motor to have a higher speed, so the submersible motor needs to have a larger power and power density.

[0003] Permanent magnet synchronous motors can show higher power density and efficiency than traditional asynchronous motors, so they are more adaptable to the well conditions of small wells. However, higher power density means higher heat generation per unit volume, and submersible permanent magnet synchronous motors work in a high-temperature and closed environment underground at the kilometer level, which places high requirements on the heat dissipation and temperature rise performance of submersible permanent magnet synchronous motors. At the same time, submersible permanent magnet motors are slender motors, which will undergo large torsional deformation during operation. The limited radial size of the motor limits the diameter of the motor shaft. If the motor shaft diameter is too small, the torsional deformation generated is too large, which will cause the rotor poles and stator teeth to not fit correctly, thereby affecting the torque output capacity of the motor, resulting in an increase in current, increased losses, and severe heat generation; if the motor shaft diameter is too large, it will affect the overall diameter of the motor, and the motor shaft will interfere with the small flat cable during assembly. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a small-diameter high-speed submersible permanent magnet synchronous motor to solve the problem that the submersible permanent magnet synchronous motor is difficult to pass through small wellbore casings and the problem of excessive torsional deformation of the motor shaft and interference during assembly.

[0005] According to the present invention, the small-diameter high-speed submersible permanent magnet synchronous motor comprises: a casing; a stator assembly fixed in the casing, the stator assembly comprising a stator core fixedly connected to the casing and a stator winding embedded in the stator core, a cavity being arranged at the center of the stator core; a rotor assembly arranged in the cavity and rotatably matched with the stator assembly, a motor head fixed at the upper end of the casing, and a tailstock fixed at the lower end of the casing. The rotor assembly comprises a stepped motor shaft located in the cavity, a plurality of rotor segments, and a plurality of stabilizing bearings, the stepped motor shaft comprising a load-bearing shaft close to the tailstock and a lead-out shaft close to the motor head connected in sequence, the diameter of the load-bearing shaft being larger than the diameter of the lead-out shaft, the lead-out shaft passing through the motor head and rotatably matched with the motor head, the stabilizing bearing and the rotor segment are spaced apart on the load-bearing shaft, and the rotor segment is key-connected to the load-bearing shaft.

[0006] Furthermore, the stator core is formed by axially stacking a plurality of stator punching sheets, the material of the stator punching sheets is 50WW310 silicon steel sheets, and a plurality of closed slots for embedding the stator windings are formed on the stator core.

[0007] Furthermore, the thickness of the stator punching sheet is 0.5 mm, the slot shape of the closed slot is trapezoidal, and the number of the closed slots is 18.

[0008] Furthermore, the rotor segment is formed by stacking a plurality of silicon steel punchings in the axial direction. The material of the silicon steel punchings is 50WW310 silicon steel sheets. A plurality of magnetic steel slots are opened on the silicon steel punchings. The rotor magnetic steel is arranged in the magnetic steel slots. The rotor magnetic steel material is SmCo30H.

[0009] Furthermore, the thickness of the silicon steel punching sheet is 0.5 mm, the number of poles is 4, and the magnetic pole distribution is an internal radial type.

[0010] Furthermore, the stabilizing bearing comprises a bearing outer sleeve fixed to the rotor segment and a bearing inner sleeve rotating with the load-bearing shaft, the bearing inner sleeve and the load-bearing shaft are transitionally matched, and there is a gap between the bearing outer sleeve and the bearing inner sleeve and they are rotationally matched.

[0011] Furthermore, an anti-rotation card is placed between the bearing inner sleeve and the load-bearing shaft, and the anti-rotation card cooperates with the shaft keyway.

[0012] Furthermore, a motor oil hole is provided on the stepped motor shaft along the axis, and an oil storage groove connected to the motor oil hole is provided along the radial direction.

[0013] Furthermore, a thrust bearing is installed in the motor head for fixing the position of the rotor assembly in the axial direction. An oil filter is also installed at the upper end of the motor head to ensure that the motor oil entering the motor is clean and prevent scratching the internal structure. An oil drain hole is also provided on the outside of the tailstock for discharging the motor oil in the motor cavity.

[0014] Furthermore, the diameter of the casing is not greater than 89 mm, the length of the stator core is not greater than 6000 mm, and the rated power of the motor is not less than 60 kW.

[0015] Compared with the prior art, the small-diameter high-speed submersible permanent magnet synchronous motor provided by the present invention can adapt to the well conditions of small-bore oil wells, can smoothly pass through the production casing with a minimum inner diameter of "4-1 / 2", and can meet the use requirements of small-bore well casings and high-speed and high-load centrifugal pumps. Its motor shaft adopts a stepped motor shaft design, which reduces the diameter of the lead-out shaft in the motor head, saves more space for the motor cable connector, improves the reliability of the small flat cable connector, and solves the problem of excessive torsional deformation of the motor shaft leading to a decrease in output torque capacity. It has stronger stability during use, and its efficiency and power factor are higher than those of traditional three-phase asynchronous submersible motors, which can effectively reduce oil production costs and meet the requirements of green and efficient oil and gas production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a small-diameter high-speed submersible permanent magnet synchronous motor according to an embodiment of the present invention;

[0017] Figure 2 It is a schematic internal top view of the structure of a small-diameter high-speed submersible permanent magnet synchronous motor according to an embodiment of the present invention;

[0018] Figure 3 for Figure 1 The structural schematic diagram of the centering bearing is shown. DETAILED DESCRIPTION

[0019] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0020] Figure 1 and Figure 2 The structure of a small-diameter high-speed submersible permanent magnet synchronous motor 100 according to an embodiment of the present invention is shown. Figure 1 and Figure 2As shown, the small-diameter high-speed submersible permanent magnet synchronous motor 100 may include: a casing 5; a stator assembly 1 fixed in the casing 5, the stator assembly 1 including a stator core 6 fixedly connected to the casing 5 and a stator winding 7 embedded in the stator core 6, and a cavity 61 is provided at the center of the stator core 6; a rotor assembly 2 arranged in the cavity 61 and rotatably matched with the stator assembly 1, a motor head 3 fixed at the upper end of the casing 5, and a tailstock 4 fixed at the lower end of the casing 5. Among them, the rotor assembly 2 includes a stepped motor shaft 9, multiple rotor segments 14 and multiple stabilizing bearings 10 located in the cavity 61. The stepped motor shaft 9 may include a load-bearing shaft 18 close to the tailstock 4 and a lead-out shaft 19 close to the motor head 3 which are connected in sequence. The diameter of the load-bearing shaft 18 is larger than the diameter of the lead-out shaft 19. The lead-out shaft 19 passes through the motor head 3 and rotates with the motor head 3. The stabilizing bearings and the rotor segments 14 are spaced apart on the load-bearing shaft 18, and the rotor segments 14 are key-connected to the load-bearing shaft 18.

[0021] In the small-diameter high-speed submersible permanent magnet synchronous motor 100 of the embodiment of the present invention, by setting a stepped motor shaft 9, and setting the diameter of its bearing shaft 18 to be larger, and setting the diameter of the lead-out shaft 19 to be smaller, it is possible to ensure that the bearing shaft 18 used to bear the rotor section 14 produces a smaller torsional deformation, thereby helping to ensure that the stepped motor shaft 9 as a whole produces a smaller torsional deformation, while the smaller diameter of the lead-out shaft 19 avoids the problem of interference with the motor cable connector. The setting of the stepped motor shaft 9 not only saves more space for the motor cable connector and improves the reliability of the small flat cable connector, but also solves the problem of reduced output torque capacity due to excessive torsional deformation of the motor shaft. The rotor section 14 is installed on the bearing shaft 18 by a key connection, which is convenient for the installation and fixation of the rotor section 14 on the one hand, and helps to improve the torque output capacity of the motor on the other hand.

[0022] In such Figure 2 In the preferred embodiment shown, the bearing shaft 18 may be provided with a plurality of shaft keyways 20 in the axial direction, and the rotor segment 14 may be provided with a key 8 that matches the shaft keyway 20, and the key 8 of the rotor segment 14 may be installed in the shaft keyway 20. The stator core 6 may be pressed into the housing 5 by a horizontal press. A lead-out shaft hole may be formed inside the motor head 3, and the lead-out shaft 19 passes through the lead-out shaft hole and rotates with the motor head 3. The motor head 3 and the tailstock 4 may be threadedly connected to the two ends of the stator assembly 1, respectively.

[0023] According to the present invention, in Figure 2 In the preferred embodiment shown, the stator core 6 may be formed by axially stacking a plurality of stator punching sheets, the material of the stator punching sheets may be 50WW310 silicon steel sheets, and a plurality of closed slots 71 for embedding the stator winding 7 may be formed on the stator core 6 .

[0024] Furthermore, the thickness of the stator punching sheet is preferably 0.5 mm, the groove shape of the closed slot 71 is preferably trapezoidal, and the number of the closed slots is preferably 18.

[0025] The rotor segment 14 can be formed by stacking a plurality of silicon steel punchings in the axial direction. The material of the silicon steel punchings can be 50WW310 silicon steel sheets. A plurality of magnetic steel slots 15 can be opened on the silicon steel punchings. The magnetic steel slots 15 are provided with rotor magnetic steels 12. The rotor magnetic steel material can be SmCo30H.

[0026] Furthermore, the thickness of the silicon steel punching sheet is preferably 0.5 mm, the number of poles is preferably 4, and the magnetic pole distribution is preferably an internal radial type.

[0027] like Figure 2 As shown, the silicon steel punching sheet is also provided with a motor shaft hole 141, a pull rod hole 11 and a self-rivet point 13.

[0028] According to the present invention, in Figure 1 and Figure 3 In the preferred embodiment shown, the stabilizing bearing 10 may include a bearing outer sleeve 16 fixed to the rotor section 14 and a bearing inner sleeve 17 rotating with the load-bearing shaft 18, the bearing inner sleeve 17 and the load-bearing shaft 18 are transitionally matched, and there is a gap between the bearing outer sleeve 16 and the bearing inner sleeve 18 and they are rotationally matched. In this embodiment, the inner surface of the bearing outer sleeve 16 and the outer surface of the bearing inner sleeve 17 form a pair of friction pairs for supporting the motor rotor section 14 to ensure that the motor has a uniform air gap.

[0029] Preferably, if Figure 3 As shown, an anti-rotation card 21 may be placed between the bearing inner sleeve 17 and the load-bearing shaft 18 , and the anti-rotation card cooperates with the shaft keyway 20 to prevent the bearing inner sleeve 17 from rotating relative to the load-bearing shaft 18 .

[0030] In such Figure 2 In the preferred embodiment shown in FIG. 1 , the stepped motor shaft 9 may be provided with a motor oil hole 91 along the axial direction, and an oil storage groove 22 (such as a groove 22 connected to the motor oil hole 91) may be provided along the radial direction. Figure 1 and Figure 3 As shown in FIG. 1 , the oil storage groove 22 is connected to the centering bearing 10 for lubricating the centering bearing 10.

[0031] Preferably, the step motor shaft 9 may be made of 35CrMo high-strength alloy steel, and the shaft head of the step motor shaft 9 may be an involute spline.

[0032] In such Figure 1In the preferred embodiment shown, a thrust bearing 23 may be installed in the motor head 3 for fixing the position of the rotor assembly 2 in the axial direction. An oil filter 24 may also be installed at the upper end of the motor head 3 for ensuring that the motor oil entering the motor is clean and preventing scratches on the internal structure. An oil drain hole 25 may also be provided on the outer side of the tailstock 4 for discharging the motor oil in the motor cavity.

[0033] According to the present invention, in a preferred embodiment, the diameter of the casing 5 is not greater than 89 mm, the length of the stator core 6 is not greater than 6000 mm, and the rated power of the motor is not less than 60 kW.

[0034] The small-diameter, high-speed, submersible permanent magnet synchronous motor 100 of the embodiment of the present invention can adapt to the well conditions of small-bore oil wells, can smoothly pass through the production casing with a minimum inner diameter of "4-1 / 2", and meet the use requirements of high-speed and high-load centrifugal pumps. It has strong stability, and its efficiency and power factor are higher than those of traditional three-phase asynchronous submersible motors, which can effectively reduce oil production costs and meet the requirements of green and efficient oil and gas production.

[0035] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0036] In the description of the present application, it should be understood that the terms "axial", "length", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A small-diameter high-speed submersible permanent magnet synchronous motor, characterized in that: include: chassis; A stator assembly fixed in the housing, the stator assembly comprising a stator core fixedly connected to the housing and a stator winding embedded in the stator core, wherein a cavity is provided at the center of the stator core; a rotor assembly disposed in the cavity and rotatably matched with the stator assembly, a motor head fixed to the upper end of the casing, and A tailstock fixed at the lower end of the casing, Wherein, the rotor assembly includes a stepped motor shaft, a plurality of rotor segments and a plurality of stabilizing bearings located in the cavity; the stepped motor shaft includes a load-bearing shaft close to the tail stock and a lead-out shaft close to the motor head which are connected in sequence; the diameter of the load-bearing shaft is larger than the diameter of the lead-out shaft; the lead-out shaft passes through the motor head and rotatably cooperates with the motor head; the stabilizing bearing and the rotor segment are spaced apart on the load-bearing shaft; and the rotor segment is key-connected to the load-bearing shaft.

2. The small-diameter high-speed submersible permanent magnet synchronous motor according to claim 1, characterized in that: The stator core is formed by axially stacking a plurality of stator punching sheets, the material of the stator punching sheets is 50WW310 silicon steel sheets, and a plurality of closed slots for embedding the stator winding are formed on the stator core.

3. The small-diameter high-speed submersible permanent magnet synchronous motor according to claim 2, characterized in that: The thickness of the stator punching sheet is 0.5 mm, the groove shape of the closed slot is trapezoidal, and the number of the closed slots is 18.

4. The small-diameter high-speed submersible permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that: The rotor segment is formed by stacking a plurality of silicon steel punching sheets in the axial direction. The material of the silicon steel punching sheets is 50WW310 silicon steel sheets. A plurality of magnetic steel slots are opened on the silicon steel punching sheets. The magnetic steel slots are provided with rotor magnetic steels. The rotor magnetic steel material is SmCo30H.

5. The small-diameter high-speed submersible permanent magnet synchronous motor according to claim 4, characterized in that: The thickness of the silicon steel punching sheet is 0.5 mm, the number of poles is 4, and the magnetic pole distribution mode is the built-in radial type.

6. The small-diameter high-speed submersible permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that: The straightening bearing comprises a bearing outer sleeve fixed to the rotor section and a bearing inner sleeve rotating with the load-bearing shaft, the bearing inner sleeve and the load-bearing shaft are transitionally matched, and there is a gap between the bearing outer sleeve and the bearing inner sleeve and they are rotationally matched.

7. The small-diameter high-speed submersible permanent magnet synchronous motor according to claim 6, characterized in that: An anti-rotation card is placed between the bearing inner sleeve and the load-bearing shaft, and the anti-rotation card cooperates with the shaft keyway.

8. The small-diameter high-speed submersible permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that: The stepped motor shaft is provided with a motor oil hole along the axis, and is provided with an oil storage groove in radial direction and connected with the motor oil hole.

9. The small-diameter high-speed submersible permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that: A thrust bearing is installed in the motor head for fixing the position of the rotor assembly in the axial direction. An oil filter is also installed at the upper end of the motor head for ensuring that the motor oil entering the motor is clean and preventing scratches on the internal structure. An oil drain hole is also provided on the outer side of the tailstock for discharging the motor oil in the motor cavity.

10. The small-diameter high-speed submersible permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that: The diameter of the casing is not greater than 89 mm, the length of the stator core is not greater than 6000 mm, and the rated power of the motor is not less than 60 kW.

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