Axially segmented submersible permanent magnet motor

Abstract

The invention discloses an axially segmented submersible permanent magnet motor, and belongs to the field of permanent magnet motors. The stator and rotor sections are arranged along the rotating shaft, and the machine shell is arranged on the outermost side. The adjacent stator and rotor sections are connected through a centering bearing; the stator and rotor section comprises a rotor section and a stator section which are sequentially arranged from inside to outside; the upper end face and the lower end face of the alignment bearing are each provided with M axial grooves, N axial open holes and arc-shaped grooves formed between the adjacent axial grooves. The position of the axial groove corresponds to the position of the end winding; in the same stator section, each phase winding is wound in from one axial end and is wound out from the other axial end, and in the same parallel branch, the windings on different stator teeth are electrically connected in the arc-shaped grooves; and between adjacent stator sections, the windings of the same phase are connected in series in the axial opening. Under the condition that the electromagnetic performance of the submersible permanent magnet motor is not affected, the use efficiency of the axial length of the motor is improved, and the stability of the motor structure is improved.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet motors, and more specifically, relates to an axially segmented submersible permanent magnet motor. Background Art

[0002] With the continuous increase in oil and gas demand and the development of the equipment manufacturing industry, submersible motors and electric drill tool drive motors, as the core drive equipment of the oilfield well working system, have also developed rapidly. Traditional submersible motors mostly use several series-connected two-pole three-phase asynchronous motors. Such series-connected asynchronous motors will cause problems such as uneven power distribution due to different rotational speeds of the motor in each power unit and a decrease in output torque due to torsional deformation of the slender rotating shaft.

[0003] In response to the above problems, the solution of using a direct-drive permanent magnet synchronous motor to replace the original "reducer + asynchronous motor" drive system to meet the requirements of low speed and high torque has been innovatively applied to engineering practice, simplifying the drive system, avoiding the reduction of system reliability caused by the mechanical structure connection of the reducer gears, and at the same time, compared with asynchronous motors, the permanent magnet synchronous motor improves the efficiency and power factor of the system. Therefore, the application of a low-speed and high-torque direct-drive permanent magnet synchronous motor with an ultra-slender structure is particularly prominent in the downhole electric drill tool system and the submersible electric pump system.

[0004] Different from ordinary motors, the motors used to drive the downhole electric drill tool system and the submersible electric pump system have a special ultra-slender structure, which makes the winding processing technology in the stator slots difficult, and the windings are extremely prone to insulation damage and fixing loosening in the slots due to thermal expansion and contraction caused by temperature rise. For example, in the patent document with the application publication number CN201661451U, a direct-drive submersible electric screw pump is disclosed. This device cancels the reducer and the deceleration protector, and the output shaft of the permanent magnet motor is directly connected to the rotor shaft of the screw pump through a coupling, avoiding many disadvantages brought by the deceleration structure; however, due to its ultra-slender ratio of the motor (the motor slender ratio is as high as 1:50), there are difficulties in the stator winding threading process and technical bottlenecks in the rotor pole processing, which are not convenient for batch production. At the same time, due to the axial thermal expansion and contraction of the windings caused by winding heating, the inter-turn insulation of the windings in the slots is damaged, and it also brings great inconvenience to the fixing of the windings in the slots.

[0005] In order to alleviate the difficulties in winding assembly and the problems that the thermal expansion and contraction of the winding are likely to cause insulation damage and fixing loosening of the winding in the slot, a submersible direct-drive permanent magnet synchronous motor is disclosed in the patent document with the application publication number CN101969256A. This motor contains at least two permanent magnet motors. The coils of the same phase on the stator side are connected in series, and the adjacent rotor shafts are fixed through a coaxial connector, achieving the functions of simplified structure, convenient installation and maintenance. However, in the structure of this motor, the adjacent rotor shafts are fixed through a coaxial connector, which has problems such as too long connecting shaft length, low axial space utilization rate, and unstable axial connection. Moreover, the stator winding of the same phase usually winds in from one axial end and winds out from the same end. In the structure of this motor, in order to achieve the series connection of the coils of the same phase, a corresponding wire routing structure needs to be set on the motor housing, which will increase the design difficulty of the motor structure and seriously affect the mechanical strength of the motor housing. In the patent document with the authorization announcement number CN102223032B, a super-slender structure motor composed of unit combined permanent magnet synchronous motors is disclosed. This motor is a submersible motor composed of independent unit combined permanent magnet synchronous motors in the same direction. The three-phase windings of each unit motor operate in parallel, achieving complete electromagnetic and mechanical independence of each unit permanent magnet motor. However, to ensure the frequency conversion synchronous start of the combined permanent magnet synchronous motor, this submersible motor has strict requirements for the assembly process. The axis lines of the stator and rotor of each unit motor must be aligned respectively. Assembly errors will cause the shaft to be distorted and deformed, which will instead affect the electromagnetic performance of the motor. Summary of the Invention

[0006] Aiming at the defects and improvement requirements of the prior art, the present invention provides an axially segmented submersible permanent magnet motor, aiming to improve the utilization efficiency of the axial length of the motor and improve the stability of the motor structure without affecting the electromagnetic performance of the submersible permanent magnet motor.

[0007] To achieve the above object, the present invention provides an axially segmented submersible permanent magnet motor, including: a rotating shaft; a plurality of stator-rotor segments arranged on the outer side of the rotating shaft along the axial direction, and a motor housing arranged on the outer side of the plurality of stator-rotor segments; the adjacent stator-rotor segments are connected through a centering bearing; The stator-rotor segment includes a rotor segment and a stator segment arranged in sequence from the inside to the outside. There is an air gap between the rotor segment and the stator segment; the rotor segment is fixed on the outer surface of the rotating shaft; the stator segment includes a stator yoke, stator teeth arranged on the inner surface of the stator yoke along the circumferential direction, and a stator winding wound on the stator teeth; the stator yoke is fixed on the inner surface of the motor housing; On the upper and lower end faces of the centering bearing, M axial grooves and N axial openings are provided, and an arc-shaped groove is provided between adjacent axial grooves; M is the number of stator teeth, and N is the number of winding phases; the position of the axial groove corresponds to the position of the end winding of the adjacent stator segment; In the same stator segment, each phase winding winds in from one axial end and winds out from the other axial end. In the same parallel branch, the windings on different stator teeth are electrically connected in the arc-shaped grooves on the adjacent alignment bearings; between adjacent stator segments, the same phase winding is connected in series in the axial openings on the alignment bearings between the two stator segments.

[0008] Further, in the same stator segment, the ratio of the number of turns n1 and n2 of the windings on both sides of the stator tooth satisfies: minimizing the content of non-working harmonics without affecting the working harmonics.

[0009] Further, in the alignment bearing, the axial opening is arranged in the axial groove.

[0010] Further, the machine shell is an integral structure.

[0011] Further, stator yoke grooves are provided on the stator yoke, and machine shell sub-bosses that cooperate with the stator yoke grooves are provided at positions on the machine shell corresponding to the respective stator yoke grooves.

[0012] Further, in the axial opening of the alignment bearing, the two windings are connected in series through an aviation plug.

[0013] Further, in each stator segment, the stator teeth are fixed to the inner surface of the stator yoke in a detachable manner.

[0014] Further, in each stator segment, the stator teeth are assembled to the inner surface of the stator yoke through dovetail grooves and tolerance fits.

[0015] Further, in each electronic segment, the stator slots are parallel slots.

[0016] Generally speaking, through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved: (1) The present invention uses the same rotating shaft to connect multiple stator-rotor segments arranged axially, and adjacent stator-rotor segments are connected through alignment bearings, which can effectively improve the structural stability of the motor; axial grooves are provided at positions on the alignment bearings corresponding to the end windings of adjacent stator segments, which can accommodate the stator end windings, greatly increasing the utilization efficiency of the axial length of the motor; in the same stator segment, each phase winding winds in from one axial end and winds out from the other axial end, axial openings are provided in the alignment bearings, and the same phase winding in adjacent stator segments is connected in series in the axial openings on the alignment bearings between the two stator segments, which is convenient for control and easy to achieve synchronous operation, avoiding problems such as uneven power distribution due to inconsistent speeds and torque reduction caused by torsional deformation of the slender rotating shaft. At the same time, the specific winding winding method makes the number of turns of the winding in the slot half a turn less than that of other conventional windings in the slot, which can effectively reduce the requirement for the voltage level of the voltage source.

[0017] (2) In this embodiment, in the same stator segment, each phase winding winds in from one axial end and winds out from the other axial end, such that the number of turns of the windings on both sides of the same stator tooth differs by 1. Thus, the ratio of the number of turns of the windings on both sides of the same stator tooth can be adjusted by adjusting the number of turns of the windings. In a preferred embodiment of the present invention, in the same stator segment, the ratio of the number of turns n1 and n2 of the windings on both sides of the stator tooth satisfies: without affecting the working harmonics, minimizing the content of non-working harmonics, thereby being able to generate specific harmonics for eliminating specific harmonics in the air gap of the motor and improving the working characteristics of the motor.

[0018] (3) In a preferred embodiment of the present invention, the axial openings for connecting the windings of the same phase between adjacent stator segments are arranged within the axial slots, which can improve the mechanical strength of the centering bearing while ensuring the realization of related functions.

[0019] (4) In a preferred embodiment of the present invention, the machine housing adopts an integrated structure with good mechanical strength. In a further preferred embodiment thereof, stator yoke grooves are provided on the yoke, and machine housing sub-protrusions that cooperate with the stator yoke grooves are provided at positions on the machine housing corresponding to the respective stator yoke grooves. The stator is fixed through the mutual cooperation of the stator yoke grooves and the machine housing sub-protrusions. The structural design is simple and does not affect the mechanical strength of the machine housing.

[0020] (5) In a preferred embodiment of the present invention, within the axial openings of the centering bearing, the two windings are connected in series through an aviation plug, which can effectively ensure the reliability of the electrical connection.

[0021] (6) In a preferred embodiment of the present invention, the stator teeth are fixed to the inner surface of the stator yoke in a detachable manner, so that when winding the windings, the windings can be first wound on the stator teeth and then assembled, which reduces the difficulty of winding processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of an axially segmented submersible permanent magnet motor provided by an embodiment of the present invention.

[0023] Figure 2 It is a schematic cross-sectional view of a centering bearing provided by an embodiment of the present invention.

[0024] Figure 3 It is a wiring diagram of a stator winding provided by an embodiment of the present invention.

[0025] Figure 4 It is a schematic cross-sectional view of a stator provided by an embodiment of the present invention.

[0026] Figure 5 It is a schematic diagram of winding on partial stator teeth provided by an embodiment of the present invention.

[0027] In all the drawings, the same reference numerals are used to denote the same elements or structures, where: 1 - housing, 2 - stator teeth, 3 - stator winding, 4 - aviation plug (female), 5 - aviation plug (male), 6 - axial slot, 7 - end winding, 8 - stator yoke, 9 - axial opening, 10 - oil film, 11 - parallel winding lead-out wire, 12 - rotating shaft, 13 - rotor segment, 14 - stator yoke groove, 15 - housing boss, 16 - arc groove. Detailed implementation mode

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] In the present invention, terms such as "first", "second", etc. (if any) in the present invention and the drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0030] In order to overcome the problems that the winding processing technology in the stator slots of ultra-slender ratio synchronous motors is difficult, and the winding insulation in the slots and the fixing will be loosened due to the thermal expansion and contraction caused by temperature rise while improving the utilization efficiency of the axial length of the motor and the stability of the motor structure without affecting the electromagnetic performance of the motor, the present invention provides an axially segmented submersible permanent magnet motor. The overall concept is to axially segment the stator and rotor of the motor to reduce the winding processing technology difficulty and relieve the problems that the winding insulation in the slots and the fixing will be loosened due to the thermal expansion and contraction caused by temperature rise; an improved centering bearing is used to connect adjacent axial segments, and the winding winding method in each stator segment is improved, so that the electrical series connection of the same-phase windings between adjacent stator segments can be realized without setting a wiring structure on the housing, and the requirement for the power supply voltage level is reduced, while the connection stability between each axial segment is improved.

[0031] The following is Embodiment 1.

[0032] An axially segmented submersible permanent magnet motor, as Figures 1 to 4 shown, includes: A rotating shaft 12; a plurality of stator-rotor segments arranged outside the rotating shaft 12 and axially, and a housing 1 arranged outside the plurality of stator-rotor segments; adjacent stator-rotor segments are connected by a centering bearing; The stator-rotor section includes a rotor section 13 and a stator section arranged successively from inside to outside. An air gap is provided between the rotor section 13 and the stator section; the rotor section 13 is fixed to the outer surface of the rotating shaft 12; the stator section includes a stator yoke 8, stator teeth 2 circumferentially arranged on the inner surface of the stator yoke 8, and a stator winding 3 wound around the stator teeth 2; the stator yoke 8 is fixed to the inner surface of the machine housing 1.

[0033] By segmenting the motor circumferentially, the present invention can overcome the problems of high processing difficulty of the winding in the stator slots of the ultra-slender ratio synchronous motor and the insulation damage and fixing loosening of the winding in the slots caused by the thermal expansion and contraction of the winding due to temperature rise. At the same time, the adjacent stator-rotor sections are connected by centering bearings, which can effectively ensure the axial connection stability.

[0034] As Figure 1 and Figure 2 shown, in this embodiment, on the upper and lower end faces of the centering bearing, M axial grooves 6 and N axial openings 9 are provided, and arc-shaped grooves are provided between adjacent axial grooves 6 for electrical connection of the parallel branch lead-out wires 11 in the same stator section; the positions of the axial grooves 6 correspond to the positions of the end windings 7 of the adjacent stator sections. M is the number of stator teeth, and N is the number of winding phases. Optionally, the motor provided in this embodiment is a three-phase motor, and the number of stator teeth is 18, that is, M = 18, N = 3, and, as Figure 2 shown, in this embodiment, the 3 axial openings 9 are evenly arranged in the 3 axial grooves 6. An oil film 10 is also provided inside the centering bearing for lubrication and pressure equalization.

[0035] By providing axial grooves at the corresponding positions of the two axial end faces of the centering bearing and the end windings, the end windings can be accommodated, thereby improving the axial space utilization rate.

[0036] In this embodiment, in the same stator section, each phase winding winds in from one axial end and winds out from the other axial end, and in the same parallel branch, the windings on different stator teeth are electrically connected in the arc-shaped grooves on the adjacent centering bearings. Figure 3 Shown is the electrical distribution diagram of one of the phase windings. Optionally, the lower end is the winding inlet end, and the upper end is the winding outlet end.

[0037] As Figure 1 shown, between adjacent stator sections, the same phase windings are connected in series in the axial openings 9 of the centering bearings between the two stator sections. As an optional implementation manner, in the axial openings of the centering bearing, the two windings are connected in series through an aviation plug. Specifically, one winding is connected to the aviation plug (male) 4, and the other winding is connected to the aviation plug (female) 5, thereby realizing a stable electrical connection between the two windings.

[0038] In this embodiment, by making each phase winding in the same stator segment wind in from one axial end and wind out from the other axial end, compared with the conventional winding method, the winding-in end and the winding-out end of each phase winding are respectively located at both ends, and the number of turns of the winding is half a turn less. On the one hand, the same-phase windings between adjacent stator segments can be directly connected in series in the axial openings of the centering bearings, without the need to additionally set up a wiring structure on the housing. On the other hand, when the windings of each phase are connected in series, the requirement for the power supply voltage level can be reduced, ensuring that the motor can be normally powered even when the axial length of the motor is relatively long.

[0039] To ensure mechanical strength, in this embodiment, the housing is an integral structure. And to facilitate the fixation between the stator and the housing, as an alternative embodiment, as Figure 1 and Figure 4 shown, in this embodiment, stator yoke grooves 14 are provided on the stator yoke, and housing sub-protrusions 5 that cooperate with the stator yoke grooves are provided at positions on the housing corresponding to the stator yoke grooves. By the cooperation of the stator yoke grooves 14 and the housing sub-protrusions 15, each stator segment is fixed on the housing. In this embodiment, while axially segmenting the stator and the rotor, a structure without an independent housing is adopted. Using the "flashlight battery assembly" principle, each modular stator segment is pressed into the integrally formed motor housing with good mechanical strength, having good mechanical strength.

[0040] To further reduce the assembly difficulty of the stator windings, as an alternative embodiment, this embodiment adopts modular stator teeth. Specifically, in each stator segment, the stator teeth are fixedly arranged on the inner surface of the stator yoke in a detachable manner. More specifically, in each stator segment, the stator teeth are assembled on the inner surface of the stator yoke through dovetail grooves and tolerance fits, as Figure 4 shown. Based on this design of modular stator teeth, for the axially segmented submersible permanent magnet motor provided in this embodiment, during manufacturing and processing, the windings can be first wound on the modular stator teeth and then assembled on the stator yoke, and the winding processing is realized by embedding stator slot wedges through the stator slot wedge openings.

[0041] As a preferred embodiment, in this embodiment, as Figure 4 described, in each electronic segment, the stator slots are parallel slots to further improve the heat dissipation effect and motor efficiency, enhance mechanical strength, reduce noise and vibration, and improve electromagnetic performance.

[0042] The following is Embodiment 2.

[0043] An axially segmented submersible permanent magnet motor. This embodiment is similar to the above Embodiment 1, the difference being that in this embodiment, a further optimized design is carried out on the number of turns of the windings.

[0044] Figure 5As shown, it is a schematic diagram of the winding on some stator teeth, where A, B, and C respectively represent the three-phase windings. According to Figure 5 It can be known that since the winding adopts a winding method with less than half a turn, that is, when the stator winding 3 winds around the stator tooth 2, it winds in from one end and winds out from the other end, so that the number of turns n1 and n2 of the windings on both sides of the same stator tooth differ by 1, that is, n2 = n1 + 1. Different from the traditional winding method of winding in and out from the same end, the winding method proposed in this embodiment can control the ratio of the number of turns of the windings on both sides of the same stator tooth by controlling the number of turns of the windings. Therefore, specific harmonics can be generated through the design of the number of turns of the windings to eliminate specific harmonics in the air gap of the motor and improve the working characteristics of the motor. Based on this, in this embodiment, in the same stator segment, the ratio of the number of turns n1 and n2 of the windings on both sides of the stator tooth satisfies: minimizing the content of non-working harmonics without affecting the working harmonics.

[0045] It is easy to understand that the working harmonics of the motor are correspondingly determined by its number of slots and poles. Taking a 12-slot 10-pole motor as an example, its working harmonic is the 5th harmonic. Through parameter scanning, it can be known that when a less-than-half-turn winding with the front end winding in and the rear end winding out is adopted in each slot, and n1 / n2 = 0.875, the magnetic potential distribution generated by the stator winding is shown in Table 1. Taking the traditional method of winding in and out from the same end as a comparison, it can be seen that this embodiment effectively suppresses the useless 1st harmonic, and the reduction amplitude is as high as 97.5%. The reduction of the non-working magnetic potential harmonics is beneficial to improving the motor efficiency and reducing the motor heating at the same time; .

[0046] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An axially segmented submersible permanent magnet motor, characterized in that: include: A rotating shaft; a plurality of stator and rotor segments arranged outside the rotating shaft and arranged along the axial direction, and a casing arranged outside the plurality of stator and rotor segments; adjacent stator and rotor segments are connected via a centering bearing; The stator and rotor segments include a rotor segment and a stator segment arranged in sequence from the inside to the outside, and an air gap is arranged between the rotor segment and the stator segment; the rotor segment is fixed to the outer surface of the rotating shaft; the stator segment includes a stator yoke, stator teeth arranged on the inner surface of the stator yoke along the circumferential direction, and a stator winding wound on the stator teeth; the stator yoke is fixed to the inner surface of the housing; The upper and lower end surfaces of the centralizing bearing are both provided with M axial grooves and N axial openings, as well as arc-shaped grooves provided between adjacent axial grooves; M is the number of stator teeth, and N is the number of winding phases; the position of the axial groove corresponds to the position of the end winding of the adjacent stator segment; In the same stator segment, each phase winding is wound in from one axial end and out from the other axial end, and in the same parallel branch, the windings on different stator teeth are electrically connected in the arc-shaped grooves on adjacent centering bearings; between adjacent stator segments, the same phase winding is connected in series in the axial opening on the centering bearing between the two stator segments.

2. The axially segmented submersible permanent magnet motor according to claim 1, characterized in that: In the same stator segment, the ratio of the number of winding turns n1 and n2 on both sides of the stator teeth satisfies: minimizing the non-operating harmonic content without affecting the operating harmonics.

3. The axially segmented submersible permanent magnet motor according to claim 1 or 2, characterized in that: In the centering bearing, the axial opening is arranged in the axial groove.

4. The axially segmented submersible permanent magnet motor according to claim 1 or 2, characterized in that: The casing is an integrated structure.

5. The axially segmented submersible permanent magnet motor according to claim 4, characterized in that: The stator yoke is provided with stator yoke grooves, and the housing sub-bosses matching with the stator yoke grooves are provided at positions on the housing corresponding to the stator yoke grooves.

6. The axially segmented oil-submersible permanent magnet motor according to claim 1 or 2, characterized in that: In the axial opening of the centering bearing, the two windings are connected in series through an aviation plug.

7. The axially segmented submersible permanent magnet motor according to claim 1 or 2, characterized in that: In each stator segment, the stator teeth are detachably fixed to the inner surface of the stator yoke.

8. The axially segmented submersible permanent magnet motor according to claim 7, characterized in that: In each stator segment, the stator teeth are assembled to the inner surface of the stator yoke through dovetail grooves and tolerance fit.

9. The axially segmented oil-submersible permanent magnet motor according to claim 8, characterized in that: In each electronic segment, the stator slots are parallel slots.

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