A natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor

Abstract

The present invention relates to the technical field of precision motors and mechanical energy storage, and more specifically to a natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor, comprising a housing, a stator disposed within the housing, the stator comprising a stator core divided into multiple segments, each phase winding of the stator being symmetrically distributed 180° along the circumference to generate a 180° symmetrical couple torque, the ratio Z / m of the number of stator winding slots to the number of motor phases being an even number, a rotor disposed within the stator, and segmented permanent magnets embedded within the rotor; through radial active magnetic levitation and axial passive magnetic levitation, the rotor can be completely naturally suspended as long as the motor rotor rotates, thereby having natural, high reliability and simplicity.

Description

Technical Field

[0001] The present invention relates to the technical field of precision motors and mechanical energy storage, and more particularly to a natural electromagnetic magnetic suspension energy storage flywheel three-phase induction motor. Background Art

[0002] Flywheel energy storage uses a high-speed rotating flywheel to store energy, achieving a cyclic conversion of electrical energy and kinetic energy. It is a purely physical energy storage method.

[0003] The latest technological development in flywheel energy storage is the use of magnetic levitation technology, which allows the flywheel rotor to rotate in a fully magnetically suspended state within a vacuum environment. This minimizes friction losses, improves energy storage density and energy conversion efficiency, and extends service life. Compared with other energy storage technologies, magnetic levitation flywheel energy storage technology offers advantages such as high safety and reliability, long service life, high energy density, fast discharge response, high energy conversion efficiency, short construction period, independence from construction location, low operation and maintenance costs, and a green and pollution-free lifecycle. It has a wide range of applications and enormous market potential, making it a key technological development in the energy storage field.

[0004] The flywheel energy storage system has high energy storage density, high power density, low environmental requirements, and modularity. Its charging and discharging time can reach minutes, and it is easy to detect the depth of discharge. It can be used in a wide range of occasions. At the same time, the flywheel energy storage has a long service life and simple maintenance, which greatly reduces the cost of electricity storage.

[0005] With the continuous development of technologies such as power electronics, magnetic levitation, and new material development and research, flywheel energy storage technology has become increasingly sophisticated, and its application scope has also spread to transportation, distributed energy systems, power supply, military industry, aerospace, medical care, agriculture and other fields, becoming one of the most promising energy storage technologies.

[0006] In the flywheel energy storage system, the shaft system is an important device for power transmission and the main part of the flywheel energy self-consumption, affecting the stability, efficiency and life of the flywheel system.

[0007] Flywheel bearing systems can be categorized into mechanical bearings, contact-type magnetic lift mechanical bearings, and contactless magnetic levitation bearings. Traditional mechanical bearings exhibit significant frictional losses during operation. Flywheel energy storage systems employing mechanical bearings experience significant energy losses during the charging and discharging processes, and also exhibit relatively low rotational speeds. Contact-type magnetic lift mechanical bearings primarily utilize magnetic levitation technology to elevate the flywheel body, reducing the load on the mechanical bearings, thereby increasing the flywheel's rotational speed and extending the bearing's service life. Although contact-type magnetic lift mechanical bearings also utilize magnetic levitation technology, they do not achieve true contactless magnetic levitation. They are still essentially mechanical bearings and still bear weight during operation. Therefore, flywheels employing contact-type magnetic lift mechanical bearings have relatively low rotational speeds, typically less than 8000 RPM, and are still classified as "low-speed" flywheels. Furthermore, their bearings typically require replacement every three to four years, and regular lubrication changes are also required. This not only increases equipment replacement and labor costs, but also presents a series of challenges associated with on-site bearing replacement, such as limited space, impact on surrounding equipment, and the need for extensive equipment for disassembly, installation, and testing. In addition, the flywheel must be completely stationary to perform the bearing replacement operation. The stopping, starting and vacuuming of the flywheel system all take several hours, and this additional downtime will cause great losses to the user.

[0008] However, levitating a motor's rotor is expensive. Typically, the magnetic bearing accounts for 60% of the motor's volume, and the controller for the bearing is expensive and complex. This makes magnetic levitation motors a costly luxury, putting them out of reach. Summary of the Invention

[0009] The purpose of the present invention is to provide a natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor, which can make the rotor completely suspended through radial active magnetic levitation and axial passive magnetic levitation.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor comprises a housing, a stator disposed within the housing, the stator comprising a stator core divided into multiple segments, each phase winding of the stator being symmetrically distributed 180° along a circumference to generate a 180° symmetrical couple torque, the ratio Z / m of the number of stator winding slots to the number of motor phases being an even number, a rotor disposed within the stator, and segmented permanent magnets embedded within the rotor;

[0012] The number of winding slots Z provided on the stator is 72, the number of pole pairs P is 12, and the number of phases m of the motor is 3;

[0013] Each phase of the motor is provided with Z / m=72 / 3=24 winding coils, each phase adopts 6 branches, and the multiple windings on the three phases can generate a restoring force for the radial deviation of the rotor in 18 directions;

[0014] The pole pitch of each phase winding is τ = 6 slot pitches;

[0015] The first end of each phase generates the port of the ABC three-phase winding, and the tail end of each phase generates the midpoint O of the ABC three-phase winding, forming the A, B, and C three-phase ports of the three-phase winding and the midpoint of a three-phase winding, forming a special 180° symmetrical parallel branch three-phase winding. Each phase winding has three pairs of 180° symmetrical parallel branches;

[0016] The interior of the shell is vacuum;

[0017] The rotor has a squirrel cage structure on the outside and has P=12 pairs of permanent magnets embedded in the rotor;

[0018] The rotor is connected to the housing through an auxiliary bearing, and an elastic rubber ring is sleeved on the outside of the auxiliary bearing;

[0019] The stator core is divided into three or more sections, and the permanent magnet is divided into three or more sections;

[0020] The segment gap λ of the stator core d =δ, where δ is the electromagnetic air gap of the motor and λ is the segmented gap of the permanent magnet r =λ d , the gap between the permanent magnet segments at both ends of the rotor axis is: rd =λ r =λ d .

[0021] The beneficial effects of the present invention are:

[0022] Through radial active magnetic suspension and axial passive magnetic suspension, as long as the motor rotor rotates, the rotor can be completely suspended naturally, with natural and natural high reliability and simplicity;

[0023] It does not require any additional sensors or controllers, and has natural high reliability and simplicity. Since it does not require magnetic levitation sensors, it is greatly simplified and has enhanced control performance and intelligent diagnosis functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0025] Figure 1 This is a schematic structural diagram of the natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor of the present invention;

[0026] Figure 2This is a schematic structural diagram of the axial magnetic bearing of the present invention;

[0027] Figure 3 Schematic diagram of the stator structure and winding phase A of the present invention;

[0028] Figure 4 Schematic diagram of the stator structure and winding B phase of the present invention;

[0029] Figure 5 Schematic diagram of the stator structure and winding C phase of the present invention;

[0030] Figure 6 It is the electromagnetic design and performance simulation diagram of the present invention.

[0031] In the figure: housing 1; stator 2; rotor 3; winding 4; auxiliary bearing 5; permanent magnet 6; electrical interface 7. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings.

[0033] like Figures 1 to 6 As shown, the structure and function of the natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor are described in detail below;

[0034] A natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor includes a housing 1, wherein a stator 2 is disposed within the housing 1. The stator 2 includes a stator core divided into multiple segments. Each phase winding 4 of the stator 2 is symmetrically distributed 180° along the circumference to generate a 180° symmetrical couple torque. The ratio Z / m of the number of winding slots of the stator 2 to the number of phases of the motor is an even number. A rotor 3 is disposed within the stator 2, and the rotor 3 has segmented permanent magnets 6 embedded therein.

[0035] The rotor 3 is connected to the housing 1 through an auxiliary bearing 5;

[0036] The number of winding slots Z provided on the stator 2 is 72, the number of pole pairs P is 12, and the number of phases m of the motor is 3;

[0037] Each phase of the motor is provided with Z / m=72 / 3=24 winding coils, each phase adopts 6 branches, and the multiple windings 4 on the three phases can generate a restoring force on the radial deviation of the rotor 3 from 18 directions;

[0038] like Figure 3As shown, the pole pitch τ of the winding 4 on each phase is 6 slot pitches, and each phase has Z / m=72 / 3=24 winding coils, occupying 24 slots; the winding coils of 18 slots 1, 2, 12, 13, 14, 24, 25, 26, 36, 37, 38, 48, 49, 50, 60, 61, 62, 72 of the A-phase winding are connected in parallel to form the A-phase winding port, and the winding coils of 18 slots 6, 7, 8, 18, 19, 20, 30, 31, 32, 42, 43, 44, 45, 55, 56, 66, 67, 68 of the A-phase winding are connected in parallel to form the midpoint port O of the A-phase winding;

[0039] like Figure 4 As shown, 18-slot winding coils 5, 6, 16, 17, 18, 28, 29, 30, 40, 41, 42, 52, 53, 54, 64, 65, 66, and 4 of the B-phase winding are connected in parallel to form a B-phase winding port, and 18-slot winding coils 10, 11, 12, 22, 23, 24, 34, 35, 36, 46, 47, 48, 58, 59, 60, 70, 71, and 72 of the B-phase winding are connected in parallel to form a midpoint port O of the B-phase winding;

[0040] like Figure 5 As shown, 18-slot winding coils 9, 10, 20, 21, 22, 32, 33, 34, 44, 45, 46, 56, 57, 58, 68, 69, 70, and 8 of the C-phase winding are connected in parallel to form a C-phase winding port, and 18-slot winding coils 14, 15, 16, 26, 27, 28, 38, 39, 40, 50, 51, 52, 62, 63, 64, 2, 3, and 4 of the C-phase winding are connected in parallel to form a midpoint port O of the C-phase winding;

[0041] Each phase's leading end generates the terminals of the ABC three-phase windings, while each phase's trailing end generates the midpoint O of the ABC three-phase windings. These terminals A, B, and C of the three-phase windings and the midpoint of one three-phase winding form a special 180° symmetrical parallel branch three-phase winding. Each phase winding has three pairs of 180° symmetrical parallel branches. The currents in these 180° symmetrical parallel branches are theoretically the same when there is no deviation in the stator and rotor air gaps.

[0042] like Figure 2 As shown, in order to allow the rotor 3 to have axial magnetic suspension capability, the auxiliary bearing 5 can adopt a dedicated axial magnetic suspension bearing, and a pair of axial magnetic suspension bearings are added to the two ends of the original rotor 3, as shown in FIG. Figure 2 As shown in the figure, after simulation analysis, the axial passive magnetic suspension stiffness of this design is 2000N / 1.0mm, but the radial magnetic pull generated at the same time is 1800N / 1.0mm;

[0043] As is well known, there is an attractive force between the stator 2 and the magnetic rotor 3. The auxiliary bearing 5 can maintain the coaxiality between the stator 2 and the rotor 3 to a certain extent. However, in the present invention, the clearance between the auxiliary bearing 5 and the rotor 3 is relatively large, and the rotor 3 will be eccentric. At this time, the rotor 3 will be attracted to the side with a smaller air gap, and the back electromotive force of the parallel branch on the side with a smaller air gap will inevitably increase, and the current will decrease. On the contrary, the back electromotive force of the parallel branch on the side with a larger air gap will decrease, and the current will increase. Therefore, the radial tension on the side with a larger air gap will increase, and the radial tension on the side with a smaller air gap will decrease, which will inevitably cause the air gap to change in the direction of smaller deviation and stabilize the air gap deviation. For induction motors, even when the motor is in the starting state and has not yet started to rotate, the transformer potential, that is, the dΨ / dt induced potential, already exists. Therefore, the present invention has the ability to fully restore the centering of the radial active magnetic suspension.

[0044] The interior of the housing 1 is vacuum; the rotation of the rotor 2 can provide momentum, forming an electromagnetic magnetic levitation energy storage flywheel system;

[0045] Furthermore, the rotor 3 has a squirrel cage structure on the outside, and P=12 pairs of permanent magnets 6 are embedded in the rotor 3; thus, the rotor 3 becomes a three-phase induction synchronous motor, which can be operated as a synchronous motor or an induction motor as needed.

[0046] The auxiliary bearing 5 is fitted with an elastic rubber ring to provide mechanical cushioning and reduce motor vibration and noise. The clearance between the auxiliary bearing 5 and the rotor 3 can be increased from the traditional negative clearance to 0.1 to 1 mm. The natural electromagnetic levitation restoring force maintains the axis of the output shaft of the rotor 3 stable. Despite the presence of the auxiliary bearing 5, the natural electromagnetic levitation can still enable the motor rotor 3 to rotate with minimal energy loss, resulting in very low vibration and noise.

[0047] The segment gap λ of the stator core d =δ, where δ is the electromagnetic air gap of the motor and λ is the segmented gap of the permanent magnet 6 r =λ d , the segment gap between the permanent magnets 6 at both ends of the rotor 3 is: rd =λ r =λ d ;

[0048] The stator core is divided into three or more sections, and the permanent magnet 6 is divided into three or more sections to obtain a greater axial passive magnetic suspension capability. In the present invention, the stator core adopts 5 sections; the winding 4 does not need to be segmented along with the stator core. Figure 1 As shown, in order to improve the axial passive magnetic suspension stiffness, the stator core and the rotor 3 are divided into multiple sections;

[0049] When λ is less than 1 / 4 to 1 / 5 of the axial length of each segment, the axial magnetic suspension stiffness is almost proportional to the number of segments n. The maximum stiffness of the segmented axial passive magnetic suspension is approximately 0.95nK (N / mm), where K (N / mm) is the stiffness of a single-segment axial passive magnetic suspension. However, the effective axial operating range of the magnetic suspension is reduced to approximately 0.95λ.

[0050] Natural electromagnetic levitation technology is also applicable to induction motors. Because induction motors lack permanent magnetic interference, they are more conducive to achieving high-precision natural electromagnetic levitation. Magnetic levitation induction hub motor systems can be used in distributed electric vehicle drive systems, such as magnetically levitated all-electric vehicles, magnetically levitated all-electric high-speed trains, and large ship drive systems. The fundamental safety performance of induction motor magnetic levitation drive systems is superior, fundamentally overcoming the "locking fault." Magnetic levitation induction motor systems can also be used in energy storage flywheel systems, which offer higher fundamental reliability.

Claims

1. A natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor, comprising a housing (1), characterized in that: A stator (2) is disposed in the housing (1), the stator (2) comprising a stator core divided into multiple sections, each phase winding (4) of the stator (2) being symmetrically distributed along a circumference of 180°, generating a 180° symmetrical couple torque, the ratio Z / m of the number of winding slots of the stator (2) and the number of phases of the motor being an even number, a rotor (3) being disposed in the stator (2), and the rotor (3) having segmented permanent magnets (6) embedded therein; The number of winding slots Z provided on the stator (2) is 72, the number of pole pairs P is 12, and the number of phases m of the motor is 3; Each phase of the motor is provided with Z / m=72 / 3=24 winding coils, each phase adopts 6 branches, and the multiple windings (4) on the three phases generate restoring forces on the radial deviation of the rotor (3) from 18 directions.

2. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 1, characterized in that: The pole pitch of the winding (4) on each phase is τ=6 slot pitches.

3. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 1, characterized in that: The first end of each phase generates the port of the ABC three-phase winding, and the tail end of each phase generates the midpoint O of the ABC three-phase winding, forming the A, B, and C three-phase ports of the three-phase winding and the midpoint of a three-phase winding, forming a special 180° symmetrical parallel branch three-phase winding. Each phase winding has 3 pairs of 180° symmetrical parallel branches.

4. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 1, characterized in that: The interior of the shell (1) is vacuum.

5. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 1, characterized in that: The rotor (3) has a squirrel cage structure on the outside, and P=12 pairs of permanent magnets (6) are embedded in the rotor (3).

6. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 1, characterized in that: The rotor (3) is connected to the housing (1) via an auxiliary bearing (5), and an elastic rubber ring is sleeved on the outside of the auxiliary bearing (5).

7. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 1, characterized in that: The stator core is divided into three or more sections, and the permanent magnet (6) is divided into three or more sections.

8. The natural electromagnetic magnetic levitation energy storage flywheel three-phase induction motor according to claim 7, characterized in that: The segment gap λ of the stator core d =(1~2)δ, where δ is the electromagnetic air gap of the motor and λ is the segment gap of the permanent magnet (6) r =λ d , the segmented gaps between the permanent magnets (6) at both ends of the rotor (3) are: rd =(1.5~2)λ r =(1.5~2)λ d .

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