Dual-motor dual-rotor flywheel energy storage device

Abstract

The invention discloses a dual-motor dual-rotor flywheel energy storage device which comprises a shell which is arranged in a sealed mode. The flywheel is connected with a motor and arranged on the inner wall of the shell, and the flywheel is arranged to be in a split type; the first wheel body is arranged right above the second wheel body, so that the axial thickness of the flywheel is increased, the energy storage capacity of the whole device is improved, meanwhile, the problem of insufficient quenching depth caused by a flywheel with a large axial size can be solved, and the flywheel is arranged into a split type, so that the axial thickness of a forge piece can be reduced, and the hardenability is improved. The two groups of motors are respectively connected with the first wheel body and the second wheel body, so that the heat dissipation areas of the stators and the rotors in the motors are increased, and the problem of heat dissipation caused by the increase of the structural sizes of the stators and the rotors of the motors due to higher motor power is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flywheel energy storage, and in particular to a dual-motor dual-rotor flywheel energy storage device. BACKGROUND

[0002] Flywheel energy storage technology is a physical energy storage method, which converts electrical energy into kinetic energy for storage by driving a flywheel to rotate at high speed. When discharging, the flywheel decelerates to drive the motor to generate electricity. The core consists of a flywheel, bearings, a motor and power electronic devices, and has the characteristics of high power density, fast charging and discharging, long service life, environmental friendliness, etc., and is suitable for power grid frequency modulation, renewable energy smooth access, data center backup power and other scenarios. In order to meet the strong energy regulation and control needs of power grid frequency modulation and renewable energy smooth access on the market, flywheel energy storage technology is developing towards large energy storage capacity and high power.

[0003] The flywheel body, as the main energy storage component of the flywheel energy storage system, is generally made of metal materials or composite materials. According to the calculation formula of the radial centrifugal stress of the rotating body, the centrifugal stress is limited by the material strength. Therefore, under the condition of certain speed and material, the maximum safe diameter of the flywheel body is determined. Increasing the axial thickness of the flywheel can also increase the energy storage capacity, but this will cause the flywheel body to be too thick, resulting in insufficient hardenability of the metal flywheel during production and manufacturing, and the material heat treatment process cannot meet the requirements. Therefore, the strength of the flywheel core is lower than the preset value, and the material performance does not meet the design requirements and cannot be used.

[0004] The motor / generator, as the driving component of the flywheel, its design parameters affect the power of the flywheel energy storage system. Higher motor power means that larger driving current is needed, which necessarily requires the design of larger winding coils. As the power of the motor increases, the structure size of the stator and rotor will also increase. The increase in the size of the stator and rotor will cause more urgent heat dissipation problems.

[0005] How to solve the problem of insufficient strength of large-size flywheel core and heat dissipation of high-power motor, so as to break through the limitations of flywheel energy and motor power, is a problem that needs to be solved for existing flywheel devices. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to solve the problem of insufficient strength of large-size flywheel core and heat dissipation of high-power motor, so as to break through the limitations of flywheel energy and motor power.

[0007] The above-mentioned technical problems are solved by the following technical solution: The present invention proposes a dual-motor dual-rotor flywheel energy storage device, which includes a housing, the housing being sealed; a flywheel, the flywheel being connected to the motor and disposed on the inner wall of the housing, the flywheel being configured as a split type; by setting the motor to at least two sets according to the number of split flywheels, the heat dissipation area of ​​the motor stator and rotor can be increased, and when the motor rotates, it drives the flywheel to rotate synchronously, thereby realizing the overall device of energy storage or energy release.

[0008] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: the flywheel includes a first wheel body and a second wheel body arranged along the axial extension of the axis of the first wheel body. The axis of the first wheel body and the axis of the second wheel body coincide. The ends of the first wheel body and the second wheel body are respectively connected to the motor. By arranging the second wheel body along the axial extension of the axis of the first wheel body, the axial thickness of the flywheel can be increased, thereby improving the energy storage capacity of the overall device. By splitting the flywheel into a first wheel body and a second wheel body, the axial thickness of the forging can be reduced, thereby increasing the hardenability of the flywheel.

[0009] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: the motor includes an upper motor and a lower motor; the first wheel and the upper motor rotor are connected to the top of the housing via an upper rolling bearing; the second wheel and the lower motor rotor are connected to the bottom of the housing via a lower rolling bearing; the upper motor rotor, the first wheel, the second wheel and the lower motor rotor are all located in the axial extension direction of the same axis.

[0010] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: the top of the housing near the upper motor is connected to an upper rolling bearing via a bearing seat, and the inner ring of the upper rolling bearing is connected to the rotor of the upper motor.

[0011] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: an axial permanent magnet bearing is provided between the upper motor base and the upper motor rotor, and the axial permanent magnet bearing is used to support the weight of the upper motor rotor and the first wheel body.

[0012] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: the first wheel body and the second wheel body are connected by an elastic coupling, the elastic coupling being used to reduce the overall tortuous mode frequency of the dual-rotor shaft system.

[0013] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: an electromagnetic bearing is provided at one end of the first wheel body and the second wheel body opposite to each other; the torsional mode damping provided by the electromagnetic bearing can improve the stability of the overall dual flywheel rotor during rotation.

[0014] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: the bottom end of the housing near the lower motor is connected to a lower rolling bearing via a bearing seat, and the inner ring of the lower rolling bearing is connected to the rotor of the lower motor.

[0015] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: a permanent magnet repulsion bearing is provided between the lower motor base and the lower motor rotor, and the permanent magnet repulsion bearing is used to support the weight of the lower motor rotor and the second wheel body.

[0016] In a preferred embodiment of the dual-motor dual-rotor flywheel energy storage device of the present invention: the motor and the flywheel are separate structures with a spindle.

[0017] The beneficial effects of this invention are as follows: by setting the flywheel as a split first wheel body and a second wheel body, and the axis lines of the first wheel body and the second wheel body are located on the same axial extension line, that is, the first wheel body is set directly above the second wheel body, this setting increases the axial thickness of the flywheel and improves the energy storage of the overall device. At the same time, it can solve the problem of insufficient quenching depth caused by the large axial size flywheel. Setting the flywheel as a split type can reduce the axial thickness of the forging and increase hardenability.

[0018] By setting the motors to two sets connected to the first and second wheel bodies respectively, the heat dissipation area of ​​the stator and rotor in the electronic system is increased. This solves the heat dissipation problem caused by the increased structural size of the motor rotor and stator due to the higher motor power. In other words, the dual-motor setup doubles the power of the flywheel energy storage system unit, doubles the rotor heat dissipation area, and doubles the stator heat dissipation area. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein:

[0020] Figure 1 A cross-sectional view of the overall structure of the dual-motor, dual-rotor flywheel energy storage device is shown.

[0021] Figure 2 An enlarged view of the electromagnetic bearing position of a dual-motor, dual-rotor flywheel energy storage device is shown.

[0022] In the diagram: 1. Housing; 2. Upper rolling bearing; 3. Axial permanent magnet attraction bearing; 4. Upper motor; 41. Upper motor rotor; 42. Upper motor stator; 5. First wheel body; 6. Flexible coupling; 7. Electromagnetic bearing; 71. Electromagnetic bearing rotor; 72. Electromagnetic bearing stator; 8. Second wheel body; 9. Lower motor; 91. Lower motor rotor; 92. Lower motor stator; 10. Permanent magnet repulsion bearing; 11. Lower rolling bearing. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0025] Reference Figure 1 This embodiment provides a dual-motor dual-rotor flywheel energy storage device, including a housing 1, which is sealed; a flywheel, which is connected to the motor and disposed on the inner wall of the housing 1, and the flywheel is configured as a split type; by setting the motor to at least two sets according to the number of split flywheels, the heat dissipation area of ​​the motor stator and rotor can be increased, and the motor drives the flywheel to rotate synchronously when rotating, thereby realizing the overall device to store or release energy.

[0026] The flywheel includes a first wheel body 5 and a second wheel body 8 arranged along the axial extension of the axis of the first wheel body 5. The axis of the first wheel body 5 and the second wheel body 8 coincide. The ends of the first wheel body 5 and the second wheel body 8 are respectively connected to a motor. By arranging the second wheel body 8 along the axial extension of the axis of the first wheel body 5, the axial thickness of the flywheel can be increased, thereby improving the energy storage of the overall device. By splitting the flywheel into the first wheel body 5 and the second wheel body 8, the axial thickness of the forging can be reduced, thereby increasing the hardenability of the flywheel.

[0027] It should be noted that in existing technologies, the flywheel, as the main energy storage component of a flywheel energy storage system, is generally made of metallic or composite materials. According to the formula for calculating the radial centrifugal stress of a rotating body: σr=(3+ν) / 8*ρ*ω 2 *r 2

[0028] Where ρ = material density (kg / m3), ω = rotational angular velocity (rad / s), r = radius of the calculation point from the center (m), and ν = Poisson's ratio of the material.

[0029] As shown in the formula above, centrifugal stress is limited by material strength. Therefore, given a fixed rotational speed and material, the maximum safe diameter of the flywheel body is determined. Increasing the axial thickness of the flywheel can also improve energy storage, but this results in an excessively thick flywheel body, leading to insufficient hardenability of the metal flywheel during manufacturing and inadequate heat treatment. Consequently, the strength of the flywheel core is lower than the preset value, and the material properties do not meet the design requirements, rendering it unusable.

[0030] As the driving component of the flywheel, the design parameters of the electric motor / generator affect the power of the flywheel energy storage system. Higher motor power means a larger drive current is required, which necessitates the design of larger winding coils. Thus, with the increase in motor power, the structural dimensions of both the stator and rotor will increase accordingly. The increased size of the stator and rotor leads to more pressing heat dissipation issues. The limitations on rotor size due to heat dissipation and centrifugal stress indirectly limit the power of the electric motor / generator.

[0031] The flywheel device in this invention is symmetrically arranged along the transverse centerline of the housing 1. The flywheel is configured as a split first wheel body 5 and a second wheel body 8, and the axis of the first wheel body 5 and the second wheel body 8 are located on the same axial extension line. That is, the first wheel body 5 and the second wheel body 8 have the same structure, and the first wheel body 5 is located directly above the second wheel body 8. This configuration increases the axial thickness of the flywheel and improves the energy storage of the overall device. At the same time, it can solve the problem of insufficient quenching depth caused by the large axial size flywheel. The split design of the flywheel can reduce the axial thickness of the forging and increase the hardenability.

[0032] By setting the motors to two sets, which are connected to the first wheel body 5 and the second wheel body 8 respectively, the heat dissipation area of ​​the stator and rotor in the electronic system is increased. This solves the heat dissipation problem caused by the increased structural size of the motor rotor and stator due to the higher motor power. In other words, the dual-motor setup doubles the power of the flywheel energy storage system unit, doubles the rotor heat dissipation area, and doubles the stator heat dissipation area.

[0033] In some embodiments, the motor includes an upper motor 4 and a lower motor 9. The first wheel 5 and the upper motor rotor 41 are connected to the top of the housing 1 via an upper rolling bearing 2. The second wheel 8 and the lower motor rotor 91 are connected to the bottom of the housing 1 via a lower rolling bearing 11. The upper motor rotor 41, the first wheel 5, the second wheel 8 and the lower motor rotor 91 are all located in the axial extension direction of the same axis.

[0034] It should be noted that the upper motor 4 and the lower motor 9 are a symmetrical dual-motor structure. The stators of the upper and lower motors are fixed to the housing 1 by supports, and the motor rotors are fixedly engaged with the upper and lower shafts of the flywheel, respectively. The two motors independently extract rotor position signals based on back EMF signals to achieve torque and speed control, without relying on position sensors.

[0035] Specifically, the upper rolling bearing 2 is connected to the top of the housing 1 near the upper motor 4 via a bearing seat. The inner ring of the upper rolling bearing 2 is connected to the rotor of the upper motor 4. The weight of the rotor shaft of the dual flywheel motor is borne by the upper rolling bearing 2.

[0036] Furthermore, an axial permanent magnet bearing 3 is provided between the upper rolling bearing 2 and the rotor of the upper motor 4. The axial permanent magnet bearing 3 is used to support the weight of the upper motor rotor 41 and the first wheel body 5.

[0037] Furthermore, the first wheel body 5 and the second wheel body 8 are connected by a flexible coupling 6. The flexible coupling 6 is used to reduce the overall bending mode frequency of the dual rotor shaft system. The flexible coupling 6 is preferably a low-bending flexible coupling 6, which reduces the overall bending (split rigidity) mode frequency of the dual rotor shaft system. An electromagnetic bearing 7 is provided to provide bending mode damping, which can improve the stability of the overall dual flywheel rotors when rotating. At the same time, the upper motor 4 and the lower motor 9 also achieve synchronous rotation through the flexible coupling 6.

[0038] It should be noted that the low-bending elastic coupling 6 refers to a coupling with certain bending characteristics, allowing it to overcome bending modes at low flywheel speeds. Simultaneously, the electromagnetic bearing 7 located at the coupling position provides radial force to limit the bending vibration amplitude during bending modes, thereby improving flywheel operational stability.

[0039] Reference Figure 2 Furthermore, an electromagnetic bearing 7 is provided at one end of the first wheel body 5 and the second wheel body 8 opposite to each other. The torsional mode damping provided by the electromagnetic bearing 7 can improve the stability of the first wheel body 5 and the second wheel body 8 when rotating. The stator of the electromagnetic bearing 7, the upper motor stator 42 and the lower motor stator 92 are respectively fixed to the housing 1 by corresponding supports.

[0040] It should be noted that the electromagnetic bearing 7 provides a certain stiffness to limit the resonance amplitude at the critical bending point. The stator of the electromagnetic bearing 7 adopts a split structure to facilitate easy installation in confined spaces. During use, the rotor of the electromagnetic bearing 7 makes partial axial contact with the flexible coupling 6 to reduce the stiffness enhancement effect. At the same time, the flexible coupling 6 and the rotor of the electromagnetic bearing 7 are assembled in a split structure and then connected to the flywheel.

[0041] It should also be noted that in existing flywheel energy storage support systems, one bearing is installed at the top and one at the bottom of the flywheel rotor to provide radial support. In addition to the two bearings at the top and bottom of the flywheel energy storage rotor, an extra electromagnetic bearing 7 is installed in the middle position. This three-support system provides better radial force compared to a two-support system. It also allows for more variable modal control. Furthermore, the ability to install the electromagnetic bearing 7 in the middle position is due to the dual-flywheel structure, which is not feasible in traditional single-flywheel structures.

[0042] Furthermore, a lower rolling bearing 11 is connected to the bottom end of the housing 1 near the lower motor 9 via a bearing seat. The inner ring of the lower rolling bearing 11 is connected to the rotor of the lower motor 9, and the lower rolling bearing 11 can move axially to a relatively large extent.

[0043] Furthermore, a permanent magnet repulsion bearing 10 is provided between the lower rolling bearing 11 and the rotor of the lower motor 9. The permanent magnet repulsion bearing 10 is used to bear the weight of the lower motor rotor 91 and the second wheel body 8. The axial permanent magnet attraction bearing bears most of the weight of the upper motor rotor and the first wheel body, while the permanent magnet repulsion bearing bears most of the weight of the lower motor rotor and the second wheel body. The remaining mass of the entire dual flywheel motor rotor shaft system is borne by the upper rolling bearing.

[0044] It should be noted that the permanent magnet repulsion bearing 10 is preferably a Halbach permanent magnet repulsion bearing 10. The reason is that the Halbach permanent magnet array is a specially arranged combination structure of permanent magnets. By carefully designing the magnetization direction of adjacent magnets, the magnetic field generated by them is directionally enhanced and weakened in space, thereby forming an exceptionally strong unilateral magnetic field on one side (enhanced side) of the array, while significantly weakening the magnetic field on the other side (back side) (theoretically close to zero).

[0045] It should also be noted that the purpose of using a Halbach permanent magnet array is to provide a greater repulsive force compared to ordinary permanent magnets.

[0046] As an alternative embodiment, the motor and flywheel are separate structures with a spindle. It should be noted that in the prior art, the flywheel rotor, flywheel body and motor shaft system are made in one piece by forging. The one-piece forging blank has a large volume, large diameter variation and high forging difficulty.

[0047] In this invention, the motor shaft and flywheel body are forged separately and then assembled by flange. The diameter and shape of the motor shaft are relatively regular, and the shape of the flywheel body is also relatively regular, making forging convenient and less difficult.

[0048] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A dual-motor, dual-rotor flywheel energy storage device, characterized in that: include, The housing (1) is a sealed enclosure; The flywheel is connected to the motor and disposed on the inner wall of the housing (1), and the flywheel is configured as a split type; By setting the motor to at least two sets according to the number of split flywheels, the heat dissipation area of ​​the motor stator and rotor can be increased. When the motor rotates, it drives the flywheel to rotate synchronously, thereby realizing the energy storage or release of the whole device.

2. The dual-motor dual-rotor flywheel energy storage device according to claim 1, characterized in that: The flywheel includes a first wheel body (5) and a second wheel body (8) arranged along the axial extension of the axis of the first wheel body (5). The axis of the first wheel body (5) and the axis of the second wheel body (8) coincide. The ends of the first wheel body (5) and the second wheel body (8) are respectively connected to the motor. By setting the second wheel body (8) along the axial extension of the axis of the first wheel body (5), the axial thickness of the flywheel can be increased, thereby improving the energy storage capacity of the overall device. By dividing the flywheel into a first wheel body (5) and a second wheel body (8), the axial thickness of the forging can be reduced, thereby increasing the hardenability of the flywheel.

3. The dual-motor dual-rotor flywheel energy storage device according to claim 2, characterized in that: The motor includes an upper motor (4) and a lower motor (9), and the first wheel body (5) and the upper motor rotor (41) are connected to the top of the housing (1) through an upper rolling bearing (2); The second wheel (8) and the lower motor rotor (91) are connected to the bottom end of the housing (1) via a lower rolling bearing (11); The upper motor rotor (41), the first wheel (5), the second wheel (8), and the lower motor rotor (91) are all located in the radial extension direction of the same axis.

4. The dual-motor dual-rotor flywheel energy storage device according to claim 3, characterized in that: The housing (1) is connected to the upper rolling bearing (2) near the top of the upper motor (4) via a bearing seat. The inner ring of the upper rolling bearing (2) is connected to the rotor (41) of the upper motor.

5. The dual-motor dual-rotor flywheel energy storage device according to claim 4, characterized in that: An axial permanent magnet bearing (3) is provided between the base of the upper motor (4) and the rotor (41) of the upper motor. The axial permanent magnet bearing (3) is used to bear the weight of the upper motor rotor (41) and the first wheel body (5).

6. The dual-motor dual-rotor flywheel energy storage device according to claim 5, characterized in that: The first wheel body (5) and the second wheel body (8) are connected by an elastic coupling (6), which is used to reduce the overall tortuous mode frequency of the dual rotor shaft system.

7. The dual-motor dual-rotor flywheel energy storage device according to claim 6, characterized in that: An electromagnetic bearing (7) is provided at one end of the first wheel (5) and the second wheel (8) facing each other; The tortuous mode damping provided by the electromagnetic bearing (7) can improve the stability of the overall dual flywheel rotor during rotation.

8. The dual-motor dual-rotor flywheel energy storage device according to claim 7, characterized in that: The housing (1) is connected to the bottom end of the lower motor (9) via a bearing seat to a lower rolling bearing (11), and the inner ring of the lower rolling bearing (11) is connected to the rotor (91) of the lower motor.

9. The dual-motor dual-rotor flywheel energy storage device according to claim 8, characterized in that: A permanent magnet repulsion bearing (10) is provided between the base of the lower motor (9) and the rotor (91) of the lower motor. The permanent magnet repulsion bearing (10) is used to bear the weight of the rotor (91) of the lower motor and the second wheel (8).

10. The dual-motor dual-rotor flywheel energy storage device according to claim 1 or 9, characterized in that: The motor and the flywheel are separate structures with a spindle.

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