Stator excitation low-temperature brushless motor system with compact structure

Abstract

The invention discloses a stator excitation low-temperature brushless motor system with a compact structure, and belongs to the technical field of power generation, power transformation or power distribution. The low-temperature brushless motor system comprises a low-temperature load container and a stator excitation brushless motor arranged in the low-temperature load container, the stator excitation brushless motor comprises a fixed shaft, an outer stator, an inner stator and a rotor, the inner stator is fixedly installed on the fixed shaft, the outer stator is arranged outside the inner stator in a sleeving mode, and the rotor is arranged outside the outer stator. A double-stator structure formed by nesting the inner stator and the outer stator generates a magnetic field with an adjustable air gap in an electric excitation mode, the rotor rotates around a fixed shaft under the action of the magnetic field with the adjustable air gap, the purpose of efficiently transmitting mechanical energy in a brushless, leakage-free and low-friction mode is achieved through a motor system with high structural compactness, and the performance test requirement of a low-temperature motor is met.

Description

Technical Field

[0001] The invention discloses a compact stator excitation low-temperature brushless motor, relates to electrical and mechanical transmission equipment, and belongs to the technical field of power generation, power transformation or power distribution. Background Art

[0002] Cryogenic motors have the advantages of good cooling effect, high electromagnetic load and high power density. They have broad application prospects in petrochemical, electrified transportation and new energy fields. From the perspective of structural characteristics, cryogenic motors can be divided into cryogenic asynchronous motors, cryogenic synchronous motors and other forms of cryogenic motors.

[0003] Regarding the performance testing of low-temperature permanent magnet motors and their systems, Chinese patent CN106405417A discloses a test method for permanent magnet synchronous motors with internal immersion in liquid hydrogen, which can realize permanent magnet motor sealing performance testing, room temperature performance testing and liquid hydrogen performance testing. However, when the permanent magnet material frequently alternates between low temperature and room temperature states, there is a risk of deformation, cracking and performance changes, which in turn affects the performance of the permanent magnet motor.

[0004] For low-temperature squirrel cage or wound-rotor asynchronous motors, Poland's MIKROMA SA has manufactured a 785kW, four-pole high-pressure submersible liquefied natural gas pump asynchronous motor, which has the advantages of simple structure, firmness and reliability, but the squirrel cage asynchronous motor has the disadvantages of difficult air gap magnetic field adjustment, low control accuracy and low efficiency; although the wound-rotor synchronous motor adjusts the air gap magnetic field to meet the needs of various operating conditions, the motor must rely on brushes and slip rings to introduce or extract current, and has the natural disadvantages of slip rings being easy to wear and produce sparks, and cannot be used in flammable and explosive industrial occasions such as liquid hydrogen. In recent years, although wireless power transmission technology can realize brushless excitation of wound-rotor synchronous motors, this technology has the disadvantages of low power transmission efficiency, low system reliability and small transmission energy, which limits the practical application of this technology in the field of low-temperature motors.

[0005] For other forms of cryogenic motors, although there are reports on cryogenic ultrasonic motors, high-temperature superconducting reluctance motors, and cryogenic liquid hydrogen all-superconducting motors, the manufacture and testing of such motors are quite difficult. The cryogenic motor load characteristic measurement device based on couplings and dynamic seals also has the disadvantages of high medium leakage and high contact friction.

[0006] In summary, the defects of permanent magnet motors, squirrel cage motors, winding synchronous motors, and wireless excitation technology make the existing motors unable to meet the requirements of low-temperature motor performance testing. Therefore, the present invention aims to provide a compact stator excitation low-temperature brushless motor system to overcome the shortcomings of the prior art, which has important theoretical significance and application value for meeting the requirements of low-temperature motor performance testing. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies of the above-mentioned background technology and provide a compact stator-excited low-temperature brushless motor system to solve the technical problem that existing motors are difficult to meet the requirements of low-temperature motor performance testing. The purpose of the present invention is to achieve brushless transmission of electrical energy and leakage-free, low-friction transmission of mechanical energy through a compact low-temperature motor system.

[0008] The present invention adopts the following technical solutions to achieve the above-mentioned invention objectives: A compact stator excitation low-temperature brushless motor system comprises: a low-temperature load container and a stator excitation brushless motor placed in the low-temperature load container, wherein the stator excitation brushless motor comprises: a fixed shaft, an outer stator, an inner stator and a rotor, wherein the inner stator is fixedly mounted on the fixed shaft, the outer stator is sleeved outside the inner stator, and a double stator structure in which the inner stator and the outer stator are sleeved generates a magnetic field with an adjustable air gap by means of electric excitation, and the rotor rotates around the fixed shaft under the action of the magnetic field with the adjustable air gap.

[0009] As a further optimization solution for a compact stator-excited low-temperature brushless motor system, the inner stator includes: an inner stator support, an inner stator core, an inner stator winding bracket and an inner stator winding; the inner stator core is composed of inner stator core teeth and inner stator core tooth slots distributed along the circumference, the inner stator winding is wound on the inner stator winding bracket, the inner stator bracket wound with the inner stator winding is nested on the inner stator core teeth, the winding edge is embedded in the inner stator core tooth slot, the inner stator core after the inner stator winding bracket is nested is fixedly mounted on the stator shaft by the inner stator support sleeved inside it, and a second air gap of the motor is arranged between the inner stator core and the rotor.

[0010] As a further optimization solution for a compact stator-excited low-temperature brushless motor system, the inner stator winding has an inner stator winding end lead wire; the excitation current is connected through the inner stator winding end lead wire, or all the inner stator winding end lead wires are combined into an inner stator winding end lead wire concentrated line, and the excitation current is connected through the inner stator winding end lead wire concentrated line.

[0011] As a further optimization scheme for a compact stator-excited low-temperature brushless motor system, the stator shaft is provided with an axial hole and a radial hole; the lead wires at the ends of the inner stator windings are routed along the inner stator core slots and then introduced into the stator shaft through the radial holes, and then extend axially out of the axial holes.

[0012] As a further optimization scheme for a compact stator-excited low-temperature brushless motor system, the outer stator includes: an outer stator shell, an outer stator core and an outer stator core winding. The outer stator core is a hollow annular structure with outer stator core teeth inside. The outer stator core winding is wound on the outer stator core teeth. The outer stator core wound with the outer stator core winding is placed in the outer stator shell, and a first air gap of the motor is arranged between the outer stator core and the rotor.

[0013] As a further optimization solution for a compact stator-excited low-temperature brushless motor system, the outer stator housing is composed of a housing front cover assembly, a housing rear cover assembly and a housing base assembly.

[0014] As a further optimization solution for a compact stator-excited low-temperature brushless motor system, the rear end of the rotor is connected to the fixed shaft through a first bearing, the front cover assembly of the housing is connected to the outer side of the front end of the rotor through a second bearing, the rear cover assembly of the housing is connected to the fixed shaft, and the inner side of the front end of the rotor is fixedly mounted on the fixed shaft through a third bearing.

[0015] As a further optimization scheme for a compact stator-excited low-temperature brushless motor system, a rotating shaft torque coupling component is fixedly connected to the front end of the rotor front flange. The rotating shaft torque coupling component and the transmission torque coupling component constitute a contactless magnetic coupler. The torque output end of the transmission torque coupling component extends out of the torque transmission surface of the low-temperature load container and is connected to the torque transmission shaft.

[0016] As a further optimization scheme for a compact stator-excited low-temperature brushless motor system, the low-temperature load container is a closed container with a cavity composed of a container assembly or an open container with a cavity, the cooling medium surface or the opening surface is a torque transmission surface, a first coupling air gap is provided between the rotating shaft torque coupling component and the torque transmission surface, and a second coupling air gap is provided between the transmission torque coupling component and the torque transmission surface.

[0017] As a further optimization solution for a compact stator-excited low-temperature brushless motor system, at least one component outlet hole is provided on the surface of the cooling medium.

[0018] The present invention adopts the above technical solution and has the following beneficial effects: (1) The low-temperature brushless motor system proposed in the present invention makes full use of the internal space of the motor. It is realized by a dual-stator structure synchronous motor in which an inner stator and an outer stator are placed in a low-temperature load container. The inner stator is excited by electric excitation. Therefore, the air gap magnetic field in the inner air gap and the outer air gap is adjustable. The purpose of the invention is to achieve brushless, leakage-free, low-friction and efficient transmission of mechanical energy through a highly compact motor system, thereby meeting the performance test requirements of the low-temperature motor.

[0019] (2) In the low-temperature brushless motor system proposed in the present invention, the inner stator winding is wound on the inner stator bracket and then integrally nested on the inner stator core teeth, eliminating the double-layer dewar structure, effectively reducing the impact of external magnetic field fluctuations on the inner stator excitation, improving the quality of the excitation magnetic field and the motor torque quality, optimizing the routing of the lead wires at the end of the inner stator winding on the fixed axis, further fully utilizing the internal space of the motor, and improving the compactness of the electric excitation system.

[0020] (3) The low-temperature brushless motor system proposed in the present invention has various components made of materials with the same or similar low-temperature shrinkage rate, which overcomes the defect that permanent magnets in traditional permanent magnet motors are prone to failure. The internal stator is reliably excited by electric excitation, thereby improving the efficiency of power transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The three-dimensional cross-sectional view of a compact stator excitation low-temperature brushless motor of the present invention.

[0022] Figure 2 It is a two-dimensional cross-sectional view of a compact stator excitation low-temperature brushless motor of the present invention.

[0023] Figure 3 The exploded view of a compact stator excitation low-temperature brushless motor of the present invention.

[0024] Figure 4 This is an exploded cross-sectional view of a compact stator excitation low-temperature brushless motor of the present invention.

[0025] Figure 5 The present invention is an axial cross-sectional view of a compact stator-excited low-temperature brushless motor.

[0026] Figure 6 This is a three-dimensional diagram of the second type of cryogenic load container that can be used in the present invention.

[0027] Description of the accompanying drawings: 1. First type low temperature load container, 101. First component lead-out hole, 102. Second component lead-out hole, 103. Container upper side component, 104. Container front side component, 105. Container lower side component, 106. Container rear side component, 2. External stator shell, 201. Shell front cover component, 202. Shell rear cover component, 203. Shell base component, 3. External stator core, 301. External stator core teeth, 4. External stator winding, 5. First air gap of motor, 6. Rotor, 601. Rotor front flange, 7. Second air gap of motor, 8. Internal stator winding bracket, 9. Internal stator winding, 901 , lead wire at the end of the inner stator winding, 902, concentrated line of the lead wire at the end of the inner stator winding, 10, first bearing, 11, inner stator core, 1101, inner stator core slot, 1102, inner stator core teeth, 12, inner stator support, 13, second bearing, 14, third bearing, 15, fixed shaft, 1501, radial hole, 1502, axial hole, 16, rotating shaft torque coupling component, 17, torque transmission shaft, 18, transmission torque coupling component, 19, coupling first air gap, 20, coupling second air gap, 21, cavity, 22, second type of cryogenic load container, 23, second type of cryogenic load container cavity. DETAILED DESCRIPTION

[0028] The technical solution of the invention is described in detail below with reference to the accompanying drawings.

[0029] Combination Figures 1 to 4 The compact stator-excited low-temperature brushless motor is placed in a first-class low-temperature load container 1, and can be tested and operated at normal temperature and low temperature.

[0030] The first type of cryogenic load container 1 is a rectangular structure with a cavity 21 inside. The compact stator-excited cryogenic brushless motor is located in the cavity 21. The medium in the cavity 21 can be air, helium, hydrogen, liquid hydrogen, liquid nitrogen, liquid helium or cryogenic liquefied petroleum gas, etc. The medium plays the function of cooling the loads inside the cavity.

[0031] The first type of cryogenic load container 1 has six facades and therefore has six side components, such as the container upper component 103, the container front component 104, the container lower component 105, the container rear component 106, the container left component, and the container right component. The side components are generally stainless steel foam interlayers or stainless steel vacuum interlayers, which play a role in insulation or reducing heat transfer. Stainless steel is generally selected from non-magnetic, high-resistivity materials to avoid magnetic saturation and eddy current heating.

[0032] The container front side component 104 serves as a torque transmission surface, and its thickness is generally smaller than other side components, because this surface is a contactless transmission surface for mechanical energy, and a smaller thickness can reduce energy transmission losses.

[0033] The thickness of the lower component 105 of the container is generally greater than that of other side components because this surface is the supporting surface of the motor. A greater thickness can ensure the rigidity of the entire structure and avoid excessive deformation of the first type of cryogenic load container 1, thereby affecting the mechanical energy transmission efficiency of the motor.

[0034] The upper component 103 of the container serves as a cooling medium surface, and is provided with a first component outlet hole 101 and a second component outlet hole 102, through which the cooling medium or electrical connection wires can enter and exit.

[0035] Combination Figure 1 , Figure 3 and Figure 5 The compact stator excitation low-temperature brushless motor is composed of an outer stator housing 2, an outer stator core 3, an outer stator winding 4, a rotor 6, an inner stator winding bracket 8, an inner stator winding 9, a first bearing 10, an inner stator core 11, an inner stator support 12, a second bearing 13, a third bearing 14, a stator shaft 15, and a rotating shaft torque coupling component 16.

[0036] The outer stator housing 2 is composed of a housing front cover assembly 201, a housing rear cover assembly 202 and a housing base assembly 203. The housing front cover assembly 201, the housing rear cover assembly 202 and the housing base assembly 203 are generally made of non-magnetic materials such as aluminum alloy and stainless steel, and have a certain rigidity, which plays a role in supporting various components of the motor and maintaining the overall integrity of the structure. The housing front cover assembly 201 and the housing rear cover assembly 202 are hollowed out to reduce weight and allow medium circulation.

[0037] The outer stator core 3, the rotor 6 and the inner stator core 11 are generally made of high magnetic permeability, low electrical conductivity silicon steel sheets laminated or bonded together, which play a role in constraining the main magnetic circuit of the motor. The outer stator core 3 is a hollow annular structure with outer stator core teeth 3011 inside; the inner stator core 11 is composed of inner stator core teeth 1102 and inner stator core tooth slots 1101 distributed along the circumference.

[0038] The outer stator winding 4 is the armature winding of the motor, which is generally wound with copper wire, aluminum wire or superconducting wire, and can be a centralized or distributed winding type, and an alternating current is passed to generate a rotating magnetic field. The outer stator winding 4 is wound on the outer stator core teeth 3011 to form an armature outer stator.

[0039] A first motor air gap 5 is provided between the outer stator core 3 and the rotor 6, and a second motor air gap 7 is provided between the inner stator core 11 and the rotor 6. The air gap length is generally in the millimeter level to minimize the magnetic field loss and improve the electromechanical energy conversion efficiency. However, the air gap length cannot be too small to avoid scratches on the material due to the low-temperature shrinkage effect.

[0040] The inner stator winding 9 is the excitation winding of the motor, which is generally wound with copper wire, aluminum wire or superconducting wire. It is a single-tooth concentrated winding, wound on the inner stator winding bracket 8, and then the inner stator winding bracket wound with the inner stator winding is nested on the inner stator core teeth 1102, and the coil edge is located in the inner stator core slot 1101. The inner stator core 11 and the inner stator support 12 sleeved therein constitute the excitation inner stator.

[0041] When the outer stator winding 4 and the inner stator winding 9 are made of copper wire or aluminum wire, the electrical conductivity at low temperature is several times higher than that at normal temperature, the loss is significantly reduced, and the motor efficiency is increased.

[0042] The inner stator winding bracket 8 can be an epoxy glass fiber board (G10) bracket, or a bracket made of non-magnetic conductive materials such as aluminum alloy, pure aluminum, stainless steel, copper, etc. When high conductivity materials such as aluminum alloy, pure aluminum or copper are used, it can play a role in suppressing the influence of external magnetic field fluctuations on the inner stator excitation.

[0043] The inner stator winding end lead wire 901 is a part of the inner stator winding 9, that is, the excitation current enters the inner stator winding 9 through the inner stator winding end lead wire 901. The number of the inner stator winding end lead wires 901 is generally twice that of the inner stator winding 9, that is, a single inner stator winding 9 has two inner stator winding end lead wires 901, and the excitation current flows into and out of the two lead wires respectively.

[0044] All the inner stator winding end lead wires 901 are generally connected in parallel or in series, and finally merged into two lead wires, namely two inner stator winding end lead wire concentrated lines 902, which are directly connected to the excitation power supply.

[0045] The lead wire concentration line 902 at the end of the inner stator winding can also be eliminated, and a specific current can be passed into the outer stator winding 4 through the lead wire 901 at the end of the inner stator winding. The specific current includes multiple current components, and through the specific series-parallel relationship of the inner stator winding 9, the motor structure design and the mutual inductance between the windings, self-excitation generates an excitation magnetic field, thereby realizing a design without lead wires.

[0046] The rotor 6 is a rotating part, and the fixed shaft 15 and the outer stator housing 2 are both stationary parts, so a first bearing 10, a second bearing 13 and a third bearing 14 are provided between the rotating part and the stationary part, and all three bearings are deep groove bearings. The rear end of the rotor 6 is connected to the fixed shaft 15 through the first bearing 10; the housing front cover assembly 201 is connected to the front end outer side of the rotor 6 through the second bearing 13, and the housing rear cover assembly 202 is connected to the fixed shaft 15; the front end inner side of the rotor 6 is fixedly mounted on the fixed shaft 15 through the third bearing 14.

[0047] An inner stator support 12 is provided between the inner stator core 11 and the fixed shaft 15. The inner stator support is generally made of the same material as the outer stator housing 2, and a cavity is provided in the axial direction of the inner stator support to reduce the weight as much as possible while meeting the mechanical rigidity. The inner stator core 11 is connected to the fixed shaft 15 through the inner stator support 12 sleeved therein, and the armature outer stator is sleeved outside the excitation inner stator.

[0048] The fixed shaft 15 is a hollow structure and is provided with an axial hole 1502. Radial holes 1501 are provided in the circumferential direction near the installation area of ​​the first bearing 10. The number of radial holes 1501 is twice that of the inner stator winding 9, which satisfies the requirement that the lead wire 901 at the end of the inner stator winding is routed along the inner stator core slot 1101 and then introduced into the hollow part of the fixed shaft 15 from the radial hole 1501, and finally extends axially out of the axial hole 1502 to extend the fixed shaft 15. The lead wire 901 at the end of the inner stator winding extending axially along the fixed shaft is led out from the first component lead hole 101 or the second component lead hole 102 through the current lead.

[0049] A rotating shaft torque coupling component 16 is disposed at the front end of the rotor front flange 601 , and the two are directly welded or fixed by screws to form a synchronously rotating component.

[0050] The shaft torque coupling component 16 is a disc structure, generally made of copper or aluminum. A first coupling air gap 19 is formed between the shaft torque coupling component 16 and the container front side component 104, and a second coupling air gap 20 is formed between the container front side component 104 and the transmission torque coupling component 18. The thickness of the two coupling air gaps is generally at the millimeter level to minimize mechanical energy loss. However, the air gap length cannot be too small to avoid scratches on the material due to the low-temperature shrinkage effect.

[0051] The torque transmission coupling component 18 and the rotating shaft torque coupling component 16 constitute a contactless magnetic coupling. The torque output end of the torque transmission coupling component 18 is connected to the torque transmission shaft 17. The torque transmission coupling component 18 and the torque transmission shaft 17 are directly welded or fixed by screws to form a synchronously rotating component. This structure can be redesigned or use publicly available technology.

[0052] The shaft torque coupling component 16 has an electrical conductivity several times higher at low temperature than at room temperature, the eddy current loss is reduced, and the torque transmission efficiency is increased.

[0053] Figure 6 This is a three-dimensional diagram of the second type of cryogenic load container that can be used in the present invention. According to actual needs, the first type of cryogenic load container can also be replaced by the second type of cryogenic load container 22, that is, the compact stator-excited cryogenic brushless motor is placed in the second type of cryogenic load container cavity 23.

[0054] The second type of cryogenic load container 22 is a hollow rectangular open structure with five facades and therefore five side components, which are generally stainless steel foam interlayers or stainless steel vacuum interlayers, which play a role in insulation or reducing heat transfer. Stainless steel is generally made of non-magnetic, high-resistivity material to avoid magnetic saturation and eddy current heating.

[0055] As a preferred embodiment of the present invention, any wall surface of the second type cryogenic load container 22 is selected as the torque transmission surface, and a torque transmission coupling component 18 is arranged outside the torque transmission surface.

[0056] As a preferred embodiment of the present invention, a compact stator-excited low-temperature brushless motor is horizontally placed in a second-type low-temperature load container cavity 23, an opening surface or a cooling medium surface is selected as a torque transmission surface, and a shaft torque coupling component 16 extends out of the opening surface or the cooling medium surface to achieve torque transmission on the opening surface or the outside of the cooling medium.

[0057] The above is only one embodiment of the present invention, specifically, it is implemented in a radial stator excitation low-temperature brushless motor, but this embodiment is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention, such as setting the number or form of bearings to other forms, or changing the open structure of the cavity rectangular parallelepiped to a semicircular structure, or changing the shape of components and fixings to other shapes or technologies, should be included in the protection scope of the present invention.

[0058] It should be noted that, in the embodiments, directional nouns such as "upper side", "lower side", "left side", "right side", "front side", "back side", "outer side", "inner side", or quantitative pronouns such as "a kind" and "an" are introduced, which should not be understood as limitations on the present invention, but are for the purpose of facilitating the explanation of the combination relationship of different components and the specific details of the present invention.

[0059] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compact stator excitation low temperature brushless motor system, characterized in that: include: A low-temperature load container and a stator-excited brushless motor placed in the low-temperature load container, wherein the stator-excited brushless motor comprises: a fixed shaft, an outer stator, an inner stator and a rotor, wherein the inner stator is fixedly mounted on the fixed shaft, the outer stator is sleeved outside the inner stator, and a double-stator structure in which the inner stator and the outer stator are sleeved generates a magnetic field with an adjustable air gap by electric excitation, and the rotor rotates around the fixed shaft under the action of the magnetic field with an adjustable air gap.

2. According to claim 1, a compact stator excitation low-temperature brushless motor system is characterized in that: The inner stator comprises: an inner stator support, an inner stator core, an inner stator winding support and an inner stator winding; the inner stator core is composed of inner stator core teeth and inner stator core tooth slots distributed along the circumference; the inner stator winding is wound on the inner stator winding support; the inner stator support wound with the inner stator winding is nested on the inner stator core teeth; the winding edge is embedded in the inner stator core tooth slot; the inner stator core after the inner stator winding support is nested is fixedly mounted on the fixed shaft through the inner stator support sleeved inside it; a second air gap of the motor is arranged between the inner stator core and the rotor.

3. According to claim 2, a compact stator excitation low-temperature brushless motor system is characterized in that: The inner stator winding has an inner stator winding end lead wire; the excitation current is connected through the inner stator winding end lead wire, or all the inner stator winding end lead wires are combined into an inner stator winding end lead wire concentrated line, and the excitation current is connected through the inner stator winding end lead wire concentrated line.

4. According to claim 3, a compact stator excitation low-temperature brushless motor system is characterized in that: The fixed shaft is provided with an axial hole and a radial hole; the lead wire of the inner stator winding end is routed along the inner stator core slot, introduced into the fixed shaft from the radial hole, and then extends out of the fixed shaft axially from the axial hole.

5. A compact stator excitation low temperature brushless motor system according to any one of claims 1 to 4, characterized in that: The outer stator comprises: an outer stator shell, an outer stator core and an outer stator core winding. The outer stator core is a hollow annular structure with outer stator core teeth inside. The outer stator core winding is wound on the outer stator core teeth. The outer stator core wound with the outer stator core winding is placed in the outer stator shell. A first air gap of the motor is arranged between the outer stator core and the rotor.

6. A compact stator excitation low temperature brushless motor system according to claim 5, characterized in that: The outer stator housing is composed of a housing front cover assembly, a housing rear cover assembly and a housing base assembly.

7. A compact stator excitation low temperature brushless motor system according to claim 6, characterized in that: The rear end of the rotor is connected to the fixed shaft through a first bearing, the front cover assembly of the housing is connected to the outer side of the front end of the rotor through a second bearing, the rear cover assembly of the housing is connected to the fixed shaft, and the inner side of the front end of the rotor is fixedly mounted on the fixed shaft through a third bearing.

8. The compact stator excitation low-temperature brushless motor system according to claim 7, characterized in that: A rotating shaft torque coupling component is fixedly connected to the front end of the rotor front flange. The rotating shaft torque coupling component and the transmission torque coupling component constitute a contactless magnetic coupler. The torque output end of the transmission torque coupling component extends out of the torque transmission surface of the low-temperature load container and is connected to the torque transmission shaft.

9. A compact stator excitation low temperature brushless motor system according to claim 8, characterized in that: The low-temperature load container is a closed container with a cavity composed of a container assembly or an open container with a cavity, the cooling medium surface or the opening surface is a torque transmission surface, a first coupling air gap is provided between the rotating shaft torque coupling component and the torque transmission surface, and a second coupling air gap is provided between the transmission torque coupling component and the torque transmission surface.

10. A compact stator excitation low temperature brushless motor system according to claim 9, characterized in that: At least one component outlet hole is arranged on the cooling medium surface.

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