Flywheel energy storage system and heat dissipation method thereof

Abstract

The invention relates to the technical field of flywheel energy storage, and discloses a flywheel energy storage system and a heat dissipation method thereof. The flywheel energy storage system comprises a sealing cavity, a motor arranged in the sealing cavity and a flywheel body with a taper structure; the flywheel body rotates at a high speed in the sealed cavity, residual gas in the sealed cavity forms a pressure gradient around the flywheel body, a relative high-pressure area and a relative low-pressure area are formed in the cavity, gas in the relative high-pressure area serves as a heat transfer medium, and gas in the relative low-pressure area serves as a heat transfer medium. Heat generated during operation of the motor is transferred out; and in the relative low-pressure area, the friction resistance borne by the flywheel body during high-speed rotation is reduced, and heat generated by a system is reduced. The flywheel energy storage system synchronously solves the problem of mechanical damage risk caused by system heat dissipation and out-of-control flywheel.

Description

Technical Field

[0001] This invention relates to the field of flywheel energy storage technology, and in particular to a flywheel energy storage system and its heat dissipation method. Background Technology

[0002] Flywheel energy storage systems are electromechanical energy conversion storage devices that use a bidirectional motor (electric / generator reversible) to convert and store electrical energy between the mechanical kinetic energy of a high-speed flywheel. They can then be connected to different types of loads through frequency regulation, rectification, and constant voltage methods. In recent years, with technological advancements and the increasing prominence of environmental issues, the technological advantages of flywheel energy storage have received growing attention, and its technological prospects are exceptionally broad.

[0003] Flywheels and motors are typically installed in a vacuum chamber to reduce air resistance and windage losses, thereby improving system efficiency. However, due to other losses such as hysteresis and eddy current losses, and the presence of a vacuum gap, the motor generates a significant amount of heat during the driving and braking of the flywheel. This heat cannot be adequately dissipated by radiation alone, leading to excessively high internal motor temperatures. This is a major reason why flywheel energy storage systems cannot operate continuously for extended periods, and it has become a significant factor restricting the development of flywheel energy storage technology.

[0004] To address this issue, existing technological approaches mainly focus on improving motor design to reduce eddy current losses; enhancing internal heat conduction and stator-rotor radiative heat transfer; and hollow shaft cooling. However, these solutions are difficult and costly to modify for improved cooling and heat dissipation, and they do not fully utilize the structural and operational characteristics of the flywheel energy storage device itself.

[0005] To increase energy storage density, flywheels are designed to operate at very high speeds. This increases the centrifugal force they experience. If defects exist during the flywheel system's manufacturing process, there is a risk of the flywheel going out of control or even disintegrating, posing serious safety risks to testing personnel and surrounding equipment. The mechanical injury risks caused by structural defects or uncontrolled forces in flywheel systems severely restrict the development of flywheel energy storage technology. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in related technologies. To this end, the present invention provides a flywheel energy storage system and a heat dissipation method thereof.

[0007] A heat dissipation method for a flywheel energy storage system. The flywheel energy storage system includes a sealed cavity, a motor installed inside the sealed cavity, and a flywheel body with a tapered structure; The motor is driven to make the flywheel body with a tapered structure rotate at high speed in the sealed cavity, forming a linear velocity gradient on the surface of the flywheel body; this causes the residual gas in the sealed cavity to form a pressure gradient around the flywheel body, creating a relatively high-pressure region and a relatively low-pressure region in the cavity.

[0008] Furthermore, the gas in the relatively high-pressure area serves as a heat transfer medium to transfer the heat generated by the motor during operation. The motor is located in a relatively high voltage area.

[0009] Furthermore, within the relatively low-pressure region, the frictional resistance experienced by the flywheel body during high-speed rotation is reduced, thereby reducing the heat generated by the system; The flywheel body is located in a relatively low-pressure area.

[0010] A flywheel energy storage system, comprising, The sealed cavity provides a vacuum operating environment; An electric motor is installed inside the sealed cavity to realize the mutual conversion of electrical energy and mechanical kinetic energy; The flywheel body is disposed within the sealed cavity and is linked to the motor; The flywheel body has a tapered structure.

[0011] Furthermore, the flywheel body is coaxially arranged with the motor.

[0012] Furthermore, the tapered structure is configured such that the diameter of the first end is larger than the diameter of the second end. The first end is far away from the motor, and the second end is close to the motor; When the flywheel body rotates, a relatively high-pressure area and a relatively low-pressure area are formed in the sealed cavity.

[0013] Furthermore, the main body of the flywheel is located in the relatively low-pressure region to reduce the frictional resistance when the flywheel rotates.

[0014] Furthermore, when the flywheel body experiences force loss of control and detaches from the rotation axis, a constraint force is provided by the gas pressure difference to move away from the motor and stop its rotation.

[0015] Furthermore, it also includes bearings, which are located at both ends of the motor and flywheel body to support the motor and flywheel body; The bearing is a ball bearing or a magnetic levitation bearing.

[0016] Furthermore, the taper of the flywheel body is less than 1°.

[0017] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1. Effectively improves the vacuum level around the flywheel body, reduces frictional resistance, and improves system efficiency.

[0018] 2. By relatively increasing the gas density around the motor and reducing its vacuum level, the motor can dissipate heat through gas exchange, thereby improving its service life and reliability.

[0019] 3. By changing the structure of the flywheel body, the purpose of automatic gas separation was achieved, which simplified the system structure complexity, reduced the difficulty of equipment manufacturing, and improved the reliability of system operation.

[0020] 4. The flywheel body is designed with a tapered structure. When encountering uncontrolled force, regardless of whether the flywheel body has broken away from the original shaft constraint and vacuum cavity, the system will spontaneously provide a downward constraint force, forcing the flywheel body to stop flying and reducing the risk of mechanical damage.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 These are schematic diagrams of the flywheel energy storage system and the flywheel body with a tapered shape, according to the present invention.

[0024] Figure label: 1. Bearing; 2. Motor; 3. Flywheel body; 4. Sealed cavity. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but should not be used to limit the scope of this invention.

[0026] Based on a thorough summary of the problems existing in the design and heat dissipation technology of existing flywheel energy storage structures, this invention optimizes the structure of the flywheel energy storage system in an effort to reduce the risks to equipment systems, personnel and motors when the flywheel goes out of control, and improves the heat dissipation performance of the motor.

[0027] The innovation of this invention lies in the detailed analysis of the structure of existing flywheel energy storage systems; existing flywheel systems all adopt a symmetrical structural design. At the same time, it was found that although existing flywheel energy storage systems generally use vacuum chambers to reduce the frictional resistance of the flywheel and reduce its energy loss, considering the overall structural pressure resistance, the chamber is not actually an absolute vacuum, but only a relatively high vacuum. The remaining gas inside can be fully utilized to dissipate heat from the motor.

[0028] Other approaches employ the method of injecting a certain amount of inert gas into the vacuum chamber to control the vacuum level, aiming to achieve a balance between flywheel energy loss and motor heat dissipation. However, this approach requires extensive testing under various operating conditions to determine a tolerable range, as a high vacuum level results in poor heat dissipation, while a low vacuum level leads to high flywheel energy loss. Furthermore, different operating speeds of the components also affect the range of vacuum levels that can be selected.

[0029] Based on this, this application also considers the mechanical damage that may be caused by flywheel runaway, and makes full use of the structural features of the flywheel energy storage system to enhance the heat dissipation capacity of the motor.

[0030] This invention proposes an innovative structural design to address the heat dissipation problem of the flywheel motor and the force runaway problem of the flywheel system in large-capacity flywheel energy storage systems.

[0031] This invention provides a flywheel energy storage system that can be used for the retrofitting of existing flywheel energy storage devices and for the construction of new flywheel energy storage systems.

[0032] The core components of this technical solution are as follows: Figure 1 As shown: The flywheel body 3, motor 2, and bearing 1 are installed in the same cavity, where the flywheel and motor 2 rotate coaxially to complete energy exchange. Bearing 1 provides rotational support for the flywheel body 3 and motor 2.

[0033] The cavity is preferably a sealed cavity, which provides a vacuum operating environment. The vacuum level can be set according to the operating requirements of the flywheel body.

[0034] Bearing 1 is located at both ends of motor 2 and flywheel body 3 to support motor 2 and flywheel body 3; bearing 1 can be a ball bearing or a magnetic levitation bearing.

[0035] The flywheel body 3 is designed with a tapered structure, such as Figure 1As shown, the end with the larger diameter is farther away from motor 2.

[0036] Since the coaxial rotational angular velocities are the same, the end farther from motor 2 has a larger diameter and a linear velocity of V1, while the end closer to the electrode has a smaller diameter and a linear velocity of V2. At this time, v1 > v2. According to Bernoulli's principle, when the flow is at the same height, the fluid velocity and pressure are inversely proportional. Therefore, the gas density inside the wall increases from v1 to v2.

[0037] The optimized flywheel body 3 structural design scheme improves the gas distribution in the flywheel cavity according to Bernoulli's principle, making the vacuum degree of the flywheel part higher than that of the motor 2 part.

[0038] The gas distribution in other parts of the entire cavity was reconstructed. The gas around the rotating separator was pushed to one side of the motor 2, which not only reduced the energy loss of the flywheel, but also increased the gas concentration around the motor 2, which increased the concentration of the heat dissipation medium for convection and heat conduction of the motor 2. This is beneficial for the dissipation of heat generated by the motor 2 and extends the service life of the motor 2.

[0039] The above solution is beneficial in two ways: firstly, it allows the motor 2 to transfer heat to the sealed cavity for heat dissipation through heat conduction and convection of the gas inside the cavity; secondly, it reduces the risk of mechanical damage caused by flywheel force runaway.

[0040] It should be noted that regardless of whether the flywheel body 3 and the motor 2 are designed into the same cavity, the structure of the flywheel body 3 can be designed as follows: Figure 1 As shown in the tapered structure, when the flywheel body 3 detaches from the axis and rotates out of control, since the speed in the v1 direction is greater than v2 and the pressure in the v1 direction is less than v2, regardless of whether the flywheel body detaches from the cavity, the gas pressure will provide a downward constraint force to the flywheel body 3, forcing the flywheel body away from the motor and reducing the risk of mechanical damage.

[0041] This application also proposes a heat dissipation method for a flywheel energy storage system. The drive motor 2 causes the flywheel body 3 with a tapered structure to rotate at high speed in the sealed cavity 4, thereby forming a linear speed gradient on the surface of the flywheel body 3; By utilizing the linear velocity gradient, the residual gas in the sealed cavity 4 forms a pressure gradient around the flywheel body 3, thereby automatically forming a relatively high-pressure area and a relatively low-pressure area within the cavity.

[0042] The gas in the relatively high-pressure area serves as a heat transfer medium, transferring the heat generated by the motor 2 during operation.

[0043] In a relatively low-pressure region, the frictional resistance experienced by the flywheel body 3 during high-speed rotation is reduced to improve system efficiency.

[0044] The pressure gradient is used to reduce mechanical damage in the event of flywheel runaway. When the flywheel body 3 loses control of its force, the gas pressure will spontaneously provide a constraint force that can reduce the risk of mechanical damage, forcing the flywheel away from the motor 2 and gradually stop rotating.

[0045] It should be further noted that the taper of the flywheel body 3 cannot be too large. Because the flywheel body 3 rotates at a very high speed within the flywheel energy storage system, an excessively large taper would cause an excessive difference in centrifugal force between the two ends of the flywheel body 3, along with an excessive difference in air pressure. The combined effect of these two forces would result in an excessive force pulling the flywheel body 3 away from the motor 2, affecting the structural stability of the equipment. Furthermore, an excessively large difference in centrifugal force would also adversely affect the structural stability of the flywheel body 3. Therefore, the taper of the flywheel body 3 is limited to within 1°. Figure 1 To clearly show the tapered structure of the flywheel body 3, the tapering has been enlarged.

[0046] The above-mentioned heat dissipation method is an improvement and enhancement based on the existing flywheel energy storage system. It can enhance the heat dissipation effect of the motor and does not conflict with the use of water cooling or other heat dissipation methods on the motor.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat dissipation method for a flywheel energy storage system, characterized in that, The flywheel energy storage system includes a sealed cavity, a motor installed inside the sealed cavity, and a flywheel body with a tapered structure; The motor is driven to make the flywheel body with a tapered structure rotate at high speed in the sealed cavity, forming a linear velocity gradient on the surface of the flywheel body; this causes the residual gas in the sealed cavity to form a pressure gradient around the flywheel body, creating a relatively high-pressure region and a relatively low-pressure region in the cavity.

2. The heat dissipation method for the flywheel energy storage system according to claim 1, characterized in that, The gas in the relatively high-pressure area serves as a heat transfer medium, transferring the heat generated by the motor during operation. The motor is located in a relatively high voltage area.

3. The heat dissipation method for the flywheel energy storage system according to claim 1, characterized in that, Within the relatively low-pressure region, the frictional resistance experienced by the flywheel body during high-speed rotation is reduced, thereby reducing the heat generated by the system; The flywheel body is located in a relatively low-pressure area.

4. A flywheel energy storage system, characterized in that, include, The sealed cavity provides a vacuum operating environment; An electric motor is installed inside the sealed cavity to realize the mutual conversion of electrical energy and mechanical kinetic energy; The flywheel body is disposed within the sealed cavity and is linked to the motor; The flywheel body has a tapered structure.

5. The flywheel energy storage system according to claim 4, characterized in that, The flywheel body is coaxially arranged with the motor.

6. The flywheel energy storage system according to claim 4, characterized in that, The tapered structure is configured such that the diameter of the first end is larger than the diameter of the second end. The first end is far away from the motor, and the second end is close to the motor; When the flywheel body rotates, a relatively high-pressure area and a relatively low-pressure area are formed in the sealed cavity.

7. The flywheel energy storage system according to claim 6, characterized in that, The main body of the flywheel is located in the relatively low-pressure region to reduce the frictional resistance when the flywheel rotates.

8. The flywheel energy storage system according to claim 6, characterized in that, When the flywheel body experiences force loss and detaches from the rotation axis, a constraint force is provided away from the motor and stops its rotation by utilizing the gas pressure difference.

9. The flywheel energy storage system according to claim 4, characterized in that, It also includes bearings, which are located at both ends of the motor and flywheel body to support the motor and flywheel body; The bearing is a ball bearing or a magnetic levitation bearing.

10. The flywheel energy storage system according to claim 4, characterized in that, The taper of the flywheel body is less than 1°.

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