A high stability energy storage flywheel system of hybrid bearing system

Abstract

This invention discloses a high-stability energy storage flywheel system with a hybrid bearing system, comprising a flywheel rotor located in a vacuum chamber. The upper part of the flywheel rotor is unloaded by a permanent magnet bearing, and the lower part is supported by a hydrodynamic bearing. The flywheel rotor rotates and stores energy within the vacuum chamber with the permanent magnet bearing and the hydrodynamic bearing as its central axis. The vacuum chamber also contains a vibration damping component to dissipate vibrations from the flywheel rotor. This invention simplifies the rotor's dynamic characteristics; the damper, operating at its optimal modal damping ratio, exhibits strong suppression of oil film oscillations. Electromagnetic parasitic oscillations are also directly eliminated by the damper, resulting in extremely high operational stability for the flywheel rotor system.

Description

Technical Field

[0001] This invention belongs to the technical field of energy storage flywheels, and in particular to a high-stability energy storage flywheel system with a hybrid bearing system. Background Technology

[0002] Energy storage flywheel technology, due to its characteristics as a green energy technology, is environmentally friendly, insensitive to changes in ambient temperature, and allows for short-duration, high-frequency continuous charging and discharging with virtually no limit on the number of charge / discharge cycles. It is showing strong growth momentum in UPS applications and smart grid energy storage. Furthermore, energy storage flywheel systems can be applied to wind power and solar power plants, enabling rapid filtering and frequency regulation for quick grid integration, significantly improving the utilization rate of green energy. However, its high cost and limited single-unit energy storage capacity limit its application in large-scale power grid energy storage and frequency regulation. Therefore, developing low-cost, high-capacity energy storage flywheels has become a crucial task for energy storage flywheel manufacturers.

[0003] Standby losses of energy storage flywheels are a crucial indicator of the system's efficiency, with bearing wear being the primary cause. Manufacturers invest significant resources in bearing research. However, due to the significantly higher wear losses compared to other support methods, mechanical bearings are currently used by only a few manufacturers. Most manufacturers prefer non-contact bearings to support the rotor's operation, primarily employing electromagnetic bearings, superconducting magnetic bearings, and hydrodynamic film bearings.

[0004] Electromagnetic bearings solve the problem of non-contact rotor support, but they are complex in structure and expensive. Furthermore, the electromagnetic field of the bearing generates eddy currents in the rotating shaft made of soft magnetic material, leading to high rotor temperature rise. Additionally, the energy consumption of electromagnetic bearings during continuous operation is not negligible. Therefore, active electromagnetic bearings are not the first choice in technical solutions aimed at reducing the cost of energy storage flywheels.

[0005] Superconducting magnetic bearings can only be found in research papers and cutting-edge basic research. They cannot reach the practical application stage in the short term. Currently, Japan's NEDO is pursuing a technical route of 100kWh large superconducting magnetic bearing energy storage flywheel, but the actual energy storage is only 25kWh, and it has not yet reached the stage of engineering application.

[0006] Due to the limitations of Enshaw's Theorem, permanent magnet bearings can only maintain stability in one direction, either axial or radial, and cannot form a rotor support method with full permanent magnet suspension. Currently, they are only used in the position of bearing-assisted unloading.

[0007] The technical solution of using an upper magnetic bearing for unloading and a lower hydrodynamic oil film bearing for support has appeared in several patented technologies and academic papers. However, these patents and papers have avoided an important technical defect: under the influence of rotor residual weight loss and oil film oscillation, the entire rotor will exhibit low-frequency precession that is difficult to eliminate, which poses a hidden danger to the stable operation of the energy storage flywheel system.

[0008] Existing energy storage flywheel systems using permanent magnet bearings in the upper section and hydrodynamic film bearings in the lower section suffer from the following problems: once low-frequency precession in the conical pendulum mode occurs, the lower support of the rotor becomes a hinge point, and stability is restored entirely by the radial stiffness of the upper magnetic bearing and the dissipation of the upper damper (in some patents). However, the radial stiffness of the magnetic bearing and the upper damper are connected in series, becoming very weak here. Moreover, the radial stiffness of the magnetic bearing itself is very small, so it cannot eliminate low-frequency conical pendulum precession. This problem has remained unsolved.

[0009] Moreover, the energy storage flywheel operates under high current during discharge, which can easily trigger parasitic oscillations caused by electromagnetic coupling of the motor. Once electromagnetic parasitic oscillations occur, they will threaten the stability of the rotor system. This problem must also be solved.

[0010] Based on the above analysis, the significance of solving the above technical problems lies in:

[0011] To comprehensively address the aforementioned problems, this invention utilizes optimized rotor dynamics. A key feature is the placement of the rotor's center of mass at the support point of the lower bearing, with the lower bearing base connected to the lower damper. This simplifies the rotor's dynamic characteristics, making lower damper optimization much easier. A damper operating at its optimal modal damping ratio exhibits strong suppression of oil film oscillations, essentially eliminating their possibility. Furthermore, the design ensures vertical symmetry between the electric motor / generator, with the electromagnetic center also largely positioned at the lower bearing support point. This directly eliminates electromagnetic parasitic oscillation interference, resulting in extremely high operational stability for the rotor system. Summary of the Invention

[0012] In response to the problems raised above, this invention proposes a high-stability energy storage flywheel system based on a hybrid bearing system.

[0013] A high-stability energy storage flywheel system with a hybrid bearing system includes a flywheel rotor located in a vacuum chamber. The upper part of the flywheel rotor is unloaded by a permanent magnet bearing, and the lower part is supported by a hydrodynamic bearing. The flywheel rotor rotates and stores energy in the vacuum chamber with the permanent magnet bearing and the hydrodynamic bearing as the central axis. The vacuum chamber is also provided with a vibration damping component to dissipate vibrations for the flywheel rotor.

[0014] Preferably, the vacuum chamber is composed of an upper flange, an outer sleeve, and a lower flange.

[0015] More preferably, the flywheel rotor is a flat disc shape with protruding shafts at the upper and lower ends.

[0016] More preferably, the damping assembly includes a damper and at least one corrector;

[0017] The damper is connected to the hydrodynamic bearing, and the corrector is installed at the upper and / or lower end of the flywheel rotor.

[0018] More preferably, the damper includes a damping housing, the interior of which is filled with damping oil, a support spring is installed at the bottom of the damping housing, and a damping slider is installed on the support spring;

[0019] A swing spring is installed at the upper end of the damping slider, and is evenly distributed between the damping slider and the damping housing along the circumferential direction; a dynamic pressure bearing housing is installed in the center of the damping slider, and the center of mass of the flywheel rotor is placed on the fulcrum of the dynamic pressure bearing housing.

[0020] More preferably, the corrector includes a fixed ring, a corrective damper, a bearing, an inner friction pair ring, and an outer friction pair ring; the fixed ring is mounted on a protruding shaft at the upper and / or lower end of the flywheel rotor, the corrective damper and the bearing are circumferentially mounted on the outer wall of the fixed ring, the inner friction pair ring is sleeved on the bearing, and the outer friction pair ring is sleeved on the inner friction pair ring.

[0021] More preferably, it also includes motor assemblies located at both axial ends of the flywheel rotor, the motor assemblies including an upper motor, an upper motor rotor, a lower motor, and a lower motor rotor;

[0022] The upper motor and the lower motor are permanent magnet synchronous motors, and the permanent magnet material of the permanent magnet synchronous motor is distributed in a cylindrical shape on the surface of the upper and lower ends of the flywheel rotor;

[0023] The upper motor is connected to the bottom of the upper flange, and the lower motor is connected to the bottom of the lower flange;

[0024] The upper motor rotor and the lower motor rotor are press-fitted onto the upper and lower ends of the flywheel rotor. Both the upper motor rotor and the lower motor rotor are composed of permanent magnets, magnetic conductors and magnetic shielding bodies pressed together in sequence.

[0025] More preferably, the upper motor and the lower motor are located on the same vertical line and are symmetrical.

[0026] More preferably, the motor assembly further includes a motor stator, which is isolated outside the vacuum chamber, and the core of the motor stator is tightly connected to the upper flange or the lower flange.

[0027] Further preferably, it also includes a heat dissipation component, which includes an upper flange air-cooling channel and / or an upper flange cooling water chamber formed on the upper flange, and a lower flange air-cooling channel and / or a lower flange cooling water chamber formed on the lower flange.

[0028] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows:

[0029] 1. By optimizing the rotor dynamics of the flywheel rotor structure, the simplified rotor system achieves extremely high dynamic stability, which significantly reduces costs while improving the operational stability of the energy storage flywheel.

[0030] 2. In this invention, the flywheel rotor has a flat structure and is made of isotropic high-strength steel to avoid the inherent defects of composite material rotors, which have high circumferential tensile strength but low radial tensile strength, thus ensuring the stable operation of the flywheel rotor.

[0031] 3. The bearing of this invention adopts a low-power rotor support method with an upper permanent magnet bearing and a lower hydrodynamic bearing. Since the technology of hydrodynamic bearings is already mature, unnecessary risks related to bearing lifespan and reliability testing are avoided.

[0032] 4. The damper has been optimized. The damper in the optimal modal damping ratio state has a strong ability to suppress oil film oscillation, which basically eliminates the possibility of oil film oscillation.

[0033] 5. The present invention provides correctors at both the upper and lower ends of the flywheel rotor. When the flywheel is subjected to an impact, the correctors and dampers can quickly dissipate the rotor vibration and restore the rotor to stable operation.

[0034] 6. The motor designed in this invention is symmetrical from top to bottom, and the electromagnetic center is also basically placed on the fulcrum of the hydrodynamic bearing. The interference of electromagnetic parasitic oscillation is also directly eliminated by the damper, and the rotor system exhibits extremely high operating stability.

[0035] 7. This invention can use forced air cooling, circulating water cooling, or a combination of cooling methods to dissipate heat quickly. Attached Figure Description

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0037] Figure 1 This is an overall structural diagram of the energy storage flywheel of the present invention;

[0038] Figure 2 This is a schematic diagram of the motor rotor;

[0039] Figure 3 This is a schematic diagram of the unloading of a permanent magnet bearing.

[0040] Figure 4 This is a schematic diagram of a damper.

[0041] In the picture:

[0042] 1-Lower flange;

[0043] 101-Lower flange air-cooled passage; 102-Lower flange cooling water chamber; 103-Lower motor;

[0044] 2-Damper;

[0045] 201-Hydrodynamic bearing housing; 202-Damping slider; 203-Damping oil; 204-Damping housing; 205-Support spring; 206-Oscillating spring;

[0046] 3-Flywheel rotor;

[0047] 301 - Lower motor rotor; 302 - Hydrodynamic bearing; 303 - Upper motor rotor;

[0048] 4-Outerwear sleeve;

[0049] 5-Upper flange;

[0050] 501 - Upper motor; 502 - Upper flange air-cooled passage; 503 - Upper flange cooling water chamber;

[0051] 6-Corrector;

[0052] 601 - Fixed ring; 602 - Correction damping; 603 - Bearing; 604 - Inner ring of friction pair; 605 - Outer ring of friction pair;

[0053] 7-Permanent magnet bearing;

[0054] 701 - Permanent magnet inner ring; 702 - Magnetic shielding ring; 703 - Permanent magnet outer ring. Detailed Implementation

[0055] First, it should be noted that the specific structure, features, and advantages of the present invention will be described in detail below by way of examples. However, all descriptions are for illustrative purposes only and should not be construed as limiting the present invention in any way. Furthermore, any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the accompanying drawings, can still be arbitrarily combined or deleted among these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned herein. Additionally, for the sake of simplifying the drawings, the same or similar technical features may be indicated only in one place in the same drawing.

[0056] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0057] The following is in conjunction with the appendix Figure 1-4 This invention will be described in detail.

[0058] Example 1 serves as an example for illustrating the overall structure:

[0059] A high-stability energy storage flywheel system with a hybrid bearing system includes a flywheel rotor 3 located in a vacuum chamber. The upper part of the flywheel rotor 3 is unloaded by a permanent magnet bearing 7, and the lower part is supported by a hydrodynamic bearing 302. The flywheel rotor 3 rotates and stores energy within the vacuum chamber with the permanent magnet bearing 7 and the hydrodynamic bearing 302 as its central axis. The vacuum chamber also includes a vibration damping component to dissipate vibrations from the flywheel rotor 3. The vacuum chamber is formed by an upper flange 5, an outer sleeve 4, and a lower flange 1.

[0060] Working principle:

[0061] like Figure 1 As shown, the energy storage flywheel system adopts a vertical rotating structure. The upper part is unloaded by a permanent magnet bearing 7, the lower part is supported by a hydrodynamic bearing 302, and the middle part is the flywheel rotor 3. The flywheel rotor 3 is located in a vacuum chamber formed by the upper and lower flanges 1 and the outer sleeve 4, ensuring the high-speed movement of the flywheel rotor 3. The base of the hydrodynamic bearing 302 is connected to the shock absorption assembly, giving the system extremely high rotor dynamic stability.

[0062] The permanent magnet bearing 7 bears approximately 95% of the weight of the flywheel rotor 3, while the hydrodynamic bearing 302 axially bears approximately 5% of the weight of the flywheel rotor 3. The gravity load of the hydrodynamic bearing is sufficient to allow the flywheel rotor 3 to float during rotor rotation and to operate stably for a long period. This results in minimal loads on the small balls in the hydrodynamic bearing 302 and on the hydrodynamic bearing housing 201. The flywheel rotor 3 is floated by the hydrodynamic oil film on the small balls of the hydrodynamic bearing, allowing the flywheel rotor 3 to operate in a low-power state with no solid friction during long-term operation.

[0063] The permanent magnet bearing 7 uses neodymium iron boron magnets processed in sections with inner and outer double rings. The annular magnets are magnetized in an overall top-to-bottom N-S manner or in a Halbach array manner to achieve the maximum utilization rate of the magnets.

[0064] Furthermore, in this embodiment, the flywheel rotor 3 can be considered as a flat, disc-shaped component with protruding shafts at both the upper and lower ends. The protruding shafts of the flywheel rotor 3 can be integral with the rotor or assembled separately. The center of the flywheel rotor 3 can be a through hole or a semi-through hole. In this embodiment, the flywheel rotor 3 is made of high-strength steel with a tensile strength greater than 1000 MPa; materials such as 42CrMo, 42Cr, 4340, and martensitic steel can be selected. This avoids rotor damage caused by dynamic imbalance due to creep of the composite material rotor, while improving the safety and long-term operational stability of the energy storage flywheel system.

[0065] The flywheel rotor 3 has a flat shape, and the ratio of its axial moment of inertia to its polar moment of inertia is greater than 1.5.

[0066] Example 2 is an illustrative example of a vibration damping component:

[0067] Furthermore, in the embodiments, the damping assembly may include a damper 2 and at least one corrector 6;

[0068] The damper 2 is connected to the hydrodynamic bearing 302, and the corrector 6 is mounted on the protruding shaft at the upper and / or lower end of the flywheel rotor 3.

[0069] Because the bearing support point and center of mass of the flywheel rotor 3 are aligned, the flywheel rotor 3 operates very smoothly without any yaw phenomenon. When subjected to external impact, the flywheel rotor 3 moves in translational motion. In this embodiment, correctors 6 are provided at both the upper and lower ends of the flywheel rotor 3. When the flywheel is impacted, the correctors 6 and the damper 2 can quickly dissipate the rotor vibration, allowing the rotor to return to stable operation.

[0070] Damper 2 can use structural damping such as rubber damping or steel wire damping, or it can use extruded oil film damping. The corrector 6 is composed of wear-resistant materials, such as copper, aluminum alloy, or powder metallurgy.

[0071] Furthermore, in the embodiments, the damper 2 may include a damping housing 204, the interior of which is filled with damping oil 203, a support spring 205 is installed at the bottom of the damping housing 204, and a damping slider 202 is installed on the support spring 205.

[0072] A swing spring 206 is installed at the upper end of the damping slider 202 and is evenly distributed between the damping slider 202 and the damping housing 204 along the circumferential direction; a dynamic pressure bearing socket 201 is installed in the center of the damping slider 202 and the center of mass of the flywheel rotor 3 is placed on the fulcrum of the dynamic pressure bearing socket 201.

[0073] In this embodiment, the damper 2 is a squeeze oil film damper 2. When the flywheel rotor 3 encounters a critical speed during startup, the amplitude increases. The small ball of the hydrodynamic bearing 302 drives the damping slider 202, which is integrated with the hydrodynamic bearing housing 201, to move in the viscous damping oil 203, dissipating the vibration energy of the flywheel rotor 3, so that the flywheel rotor 3 can stably pass the critical speed and maintain the stable operation of the flywheel rotor 3.

[0074] Since the center of mass of the flywheel rotor 3 is located on the fulcrum of the dynamic pressure bearing housing 201, the vibration mode of the flywheel rotor 3 is the translation of its center of mass along the horizontal direction. The frequency of the lower damper 2 system, which consists of the damping slider 202, the cylindrical support spring 205 on the damper 2, and the flywheel rotor 3, is coupled to the modal frequency of the flywheel rotor 3. At this time, the lower damper has the best damping state, and the flywheel rotor 3 obtains the maximum damping efficiency and has extremely high stability.

[0075] When oil film oscillation occurs in the lower bearing support system formed by the small ball of the hydrodynamic bearing 302 and the socket of the hydrodynamic bearing 201, the frequency of the oil film oscillation is low and very close to the system frequency of the lower damper. The energy of the oil film oscillation will also be dissipated by the lower damper, destroying its oscillation maintenance conditions and causing the flywheel rotor 3 to return to stable operation.

[0076] When subjected to strong external shocks such as earthquakes, the response of the flywheel rotor 3 is a superposition effect of modal comprehensive responses. The second mode of the flywheel rotor 3 system is influenced by the modal frequency boosting effect of the gyroscopic effect, which is much higher than the rotation frequency of the flywheel rotor 3. Therefore, the flywheel rotor 3 system only responds with the first mode after being subjected to external shocks.

[0077] Since the displacement response characteristic of the flywheel rotor 3 is to move at the center of mass, i.e. the pivot point of the dynamic pressure bearing housing 201, and the dynamic pressure bearing housing 201 is directly connected to the damping slider 202, this is equivalent to a rigid body with damping flexible support at the bottom, which greatly alleviates the impact of external shocks. This is the first step of protection for the rotor system and its effect is obvious.

[0078] When a large displacement occurs on the upper part of the flywheel rotor 3, the friction pairs of the inner and outer rings of the corrector 6 at the upper and lower ends of the flywheel rotor 3 collide with each other with a low coefficient of friction and impact resistance, converting the collision energy into kinetic energy. The conical sleeve set in the inner ring converts this energy into upward motion energy, forcing the upper part of the flywheel rotor 3 to quickly return to the normal rotation axis. At the same time, under the action of reset damping and rubber, the kinetic energy converter conical sleeve quickly returns to the initial position to meet the continuous collisions.

[0079] This invention utilizes the optimized results of rotor dynamics. A key feature is that the center of mass of the flywheel rotor 3 is positioned at the fulcrum of the dynamic pressure bearing housing 201, while the base of the dynamic pressure bearing housing 201 is connected to the damping slider 202. Simultaneously, the ratio of the polar moment of inertia Ip to the equatorial moment of inertia Id of the flywheel rotor 3 is limited to less than 1. By utilizing the gyroscopic effect to boost the modal frequency, the second modal frequency of the flywheel rotor 3 system is always higher than the rotational frequency of the flywheel rotor 3, giving the system single-degree-of-freedom mechanical characteristics. Optimizing the lower damper, composed of the damping slider 202, the cylindrical support spring 205, and the damping oil 203 inside the damping housing 204, becomes very easy.

[0080] Furthermore, in another embodiment, the shaft socket of the hydrodynamic bearing 302 can be connected to the damping slider 202, with a gap between the damper housing on the outer diameter sidewall of the damper body, forming the extruded diaphragm damper 2. The damper body is connected to the base via three positioning springs, support rods, and a thin plate, etc., to maintain the centering and parallel movement of the damper body. The support rods are made of steel, copper, aluminum alloy, etc., and the thin plate is generally made of copper.

[0081] Furthermore, in the embodiments, the corrector 6 may include a fixed ring 601, a corrective damper 602, a bearing 603, an inner friction pair ring 604, and an outer friction pair ring 605. The fixed ring 601 is installed at the upper end and / or lower end of the flywheel rotor 3. The corrective damper 602 and the bearing 603 are circumferentially installed on the outer wall of the fixed ring 601. The inner friction pair ring 604 is sleeved on the bearing 603, and the outer friction pair ring 605 is sleeved on the inner friction pair ring 604.

[0082] Furthermore, in the embodiments, it can be considered to provide a corrector 6 between the upper and lower ends of the flywheel rotor 3 and the stationary part.

[0083] In this embodiment, the corrector 6 is composed of wear-resistant materials, ball bearings 603, and corrective damping 602. The wear-resistant materials are made of copper, aluminum alloy, powder metallurgy, etc., forming the friction pair. The corrective damping device 602 can be rubber damping, steel wire damping, or extrusion oil film damping. The fixed ring 601 is supported by copper, and the corrective damping 602 is made of springs and viscoelastic rubber, used to buffer and dissipate the kinetic energy of the tapered sliding sleeve of the kinetic energy converter. The inner ring 604 and outer ring 605 of the friction pair are made of materials with good wear resistance, such as copper, aluminum alloy, or powder metallurgy, or coated with wear-resistant materials such as Teflon. The bearing 603 can be a ball bearing 603, a needle bearing 603, or a self-lubricating bearing 603. The corrector 6 protects the flywheel rotor 3 system, ensuring high stability even under large external impact disturbances.

[0084] Example 3 serves as an illustrative example of a motor assembly:

[0085] Furthermore, in the embodiments, it can also be considered that the motor assembly is located at both ends of the flywheel rotor 3 along the axial direction, the motor assembly including an upper motor 501, an upper motor rotor 303, a lower motor 103 and a lower motor rotor 301;

[0086] The upper motor 501 and the lower motor 103 are permanent magnet synchronous motors, and the permanent magnet material of the permanent magnet synchronous motor is distributed in a cylindrical shape on the surface of the upper and lower ends of the flywheel rotor 3.

[0087] The upper motor 501 is connected to the bottom of the upper flange 5, and the lower motor 103 is connected to the bottom of the lower flange 1;

[0088] The upper motor rotor 303 and the lower motor rotor 301 are press-fitted to the upper and lower ends of the flywheel rotor 3. Both the upper motor rotor 303 and the lower motor rotor 301 are composed of permanent magnets, magnetic conductors and magnetic shielding bodies pressed together in sequence.

[0089] The flywheel of this invention is a hybrid bearing system that achieves axial and radial balance of the flywheel rotor, giving the flywheel high stability.

[0090] In this invention, a permanent magnet synchronous motor is used, and the permanent magnet material of the motor is distributed in a cylindrical shape on the upper and lower surfaces of the flywheel rotor 3. This avoids the flywheel rotor 3 from overheating and eliminates the need for a separate yoke to protect the magnets. Because the permanent magnet synchronous motor rotor does not overheat, the temperature of the lubricating oil in the hydrodynamic oil film bearing remains within the normal temperature range.

[0091] The flywheel rotor 3 is driven by permanent magnet synchronous motors at both ends. When the flywheel system is connected to the grid, the permanent magnet synchronous motors drive the flywheel rotor 3 to its operating speed, putting the energy storage flywheel system in standby mode. When the grid needs energy from the energy storage flywheel system, the flywheel rotor 3 begins to decelerate, and the permanent magnet synchronous motors become generators, releasing energy until the lower limit of the release speed is reached. Then, it absorbs energy from the external source again, and the permanent magnet synchronous motors drive the flywheel rotor 3 to its operating speed again, completing one working cycle.

[0092] In this invention, the permanent magnet synchronous motor rotor uses permanent magnet materials. Since there is no current inside the rotor, the eddy current losses of the induction motor rotor are avoided. There are also no copper or iron losses, resulting in low rotor heat generation. Furthermore, a circulating water channel is provided on the outer wall of the vacuum chamber sleeve, allowing for rapid heat dissipation from the rotor. The absence of rotor heat also avoids the difficulties of relying solely on radiation to dissipate heat under vacuum conditions.

[0093] In this invention, since the magnets of the motor rotor are held and fixed to the surface of the flywheel rotor 3 by the magnets, the magnets are directly protected by the body material of the flywheel rotor 3. Using cylindrical permanent magnets is more conducive to the stability of the permanent magnet material at high speeds.

[0094] In this invention, the motor rotor adopts a combined structure of permanent magnets, magnetic conductors, and magnetic shielding. The integral motor rotor ring and flywheel rotor are press-fitted together with three major components. The permanent magnet material is rare earth permanent magnet material, neodymium iron boron or samarium cobalt permanent magnet, and the shape is cylindrical, sector-shaped, etc. The permanent magnet and magnetic shielding are press-fitted together as one unit.

[0095] The motor rotor magnets are fixed to the upper and lower surfaces of the flywheel rotor 3. The magnets are protected directly using the rotor body material and magnetic shielding material, which significantly reduces the strength requirements of the yoke. The permanent magnets of the motor rotor are cylindrical or sector-shaped. The permanent magnet cage formed by the permanent magnet and the magnetic shielding material is installed by interference fit. Then, the permanent magnet and the permanent magnet cage are jointly interference fitted to the surface of the flywheel rotor 3.

[0096] The magnetic conductor materials are 45#, 20#, 42CrMo, 42Cr, 4340 and martensitic steel, and the shape is an integral circular ring or a split circular ring; the magnetic shielding material is non-magnetic stainless steel, aluminum alloy, etc., such as 304 and 6061.

[0097] In this embodiment, the permanent magnet bearing 7 adopts an upper unloading magnetic bearing 603, which includes a permanent magnet outer ring 703, a magnetic isolation ring 702, and a permanent magnet inner ring 701.

[0098] The upper stationary unloading magnet can be equipped with an active magnetic bearing to adjust the magnetic pull of the upper magnet at any time, ensuring the axial force balance of the system.

[0099] The upper axial unloading magnet has a ring structure with an axial N-S pole arrangement to obtain the maximum unloading magnetic force per unit volume of magnet, unloading the weight of the motor rotor, and simultaneously achieving a dynamic parameter match for stable rotor operation, i.e., suitable radial and axial stiffness. Alternatively, split permanent magnets or single permanent magnets can be used to obtain a load-bearing capacity that can accommodate the lower hydrodynamic bearing.

[0100] Furthermore, in the embodiments, the upper motor 501 and the lower motor 103 may be located on the same vertical line and be symmetrical.

[0101] The motor, namely the energy storage flywheel electric motor / generator, is located at the upper and lower end faces of the flywheel rotor 3. It provides the rotational power and power generation capacity of the system. At the same time, the upper and lower motors provide appropriate radial stiffness to ensure the stability and shock resistance of the flywheel rotor 3. The upper and lower motors can provide balanced magnetic pull or different axial magnetic pull to reduce the volume of the axial permanent magnet at the upper end of the system and improve economy.

[0102] Furthermore, in some embodiments, the motor assembly may also include a motor stator isolated outside the vacuum chamber, the core of which is tightly connected to the upper flange 5 or the lower flange 1.

[0103] A yoke ring and a magnetic isolation ring 702 are provided between the permanent magnet material and the flywheel rotor 3. Due to the presence of the motor core and the rotor permanent magnet, the motor stator can also provide axial magnetic pull and radial stiffness of the system to the flywheel rotor 3. The radial stiffness will also change with the change of the motor magnetic field. The motor stator base is tightly fitted with the upper and lower flanges, and direct and effective circulating water can be used for heat dissipation, including forced air cooling and water cooling. Forced air cooling can be performed directly using air cooling channels, and fins can be designed on the flanges to increase the heat dissipation area and heat dissipation efficiency.

[0104] The motor stator is made of silicon steel strip wound together. The silicon steel strip is cold-rolled and non-oriented, with a thickness of 0.2 or 0.35 mm. The rotor permanent magnet material is neodymium iron boron, samarium cobalt, etc. The yoke iron ring material is 40Cr, 42Cr, 42CrMo, carbon steel, etc. The magnetic isolation ring 702 material is made of high-strength aluminum alloy 6061, 7075, non-magnetic stainless steel 304, etc.

[0105] Furthermore, in the embodiments, a vacuum isolation plate can be provided between the flywheel rotor 3 and the motor stator, and the isolation plate material can be aluminum alloy, non-magnetic stainless steel, etc.

[0106] Example 3 is an illustrative example of a heat dissipation component:

[0107] Furthermore, in the embodiments, a heat dissipation component may also be considered, which includes an upper flange air cooling channel 502 and / or an upper flange cooling water cavity 503 formed on the upper flange 5, and a lower flange air cooling channel 101 and / or a lower flange cooling water cavity 102 formed on the lower flange 1.

[0108] The motor's core base is connected to the base plate of the upper and lower flange housing, forming a good heat dissipation channel. Simultaneously, the motor stator is isolated outside the vacuum chamber, allowing the heat from the motor / generator to be connected through the water-cooled base plate of the flange housing, and finally dissipated by an air-cooled finned radiator. Since the motor stator is isolated outside the vacuum chamber, it also utilizes air cooling. Depending on the actual operating conditions of the flywheel, air cooling, water cooling, or a hybrid cooling system can be used.

[0109] Furthermore, in the embodiments, the hybrid bearing system can be considered as consisting of a permanent magnet suspension bearing, a spiral groove ball bearing, and a motor electromagnetic bearing; the hybrid bearing provides the axial force and radial stiffness of the system. The radial stiffness balance of the hybrid bearing in this system is such that the radial stiffness of the spiral groove ball bearing is equal to the sum of the radial stiffness of the permanent magnet suspension bearing and the motor electromagnetic bearing, giving the system sufficient seismic resistance.

[0110] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

[0111] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A high stability energy storage flywheel system of a hybrid bearing system comprising a flywheel rotor, characterized in that: The flywheel rotor is located in a vacuum chamber, the upper part of the flywheel rotor is unloaded by a permanent magnetic bearing, the lower part of the flywheel rotor is supported by a liquid dynamic pressure bearing, and the flywheel rotor rotates in the vacuum chamber with the permanent magnetic bearing and the liquid dynamic pressure bearing as the central axis to store energy; a damping assembly for dissipating vibration of the flywheel rotor is further arranged in the vacuum chamber; The vacuum chamber is composed of an upper flange, an outer sleeve and a lower flange. The flywheel rotor is a flat disc shape with convex shafts at the upper end and the lower end. The damping assembly comprises a damper and at least one corrector. The damper is connected with the liquid dynamic pressure bearing, and the corrector is installed on the convex shafts at the upper end and / or the lower end of the flywheel rotor. The damper comprises a damping shell, the inside of the damping shell is filled with damping oil, a supporting spring is installed at the bottom of the damping shell, and a damping slider is installed on the supporting spring; an oscillating spring is installed at the upper end of the damping slider and is uniformly distributed between the damping slider and the damping shell in the circumferential direction; a dynamic pressure bearing shaft socket is installed at the center of the damping slider, the center of gravity of the flywheel rotor is located at the fulcrum of the dynamic pressure bearing shaft socket; the base of the dynamic pressure bearing shaft socket is connected with the damping slider; and the shaft socket of the liquid dynamic pressure bearing is connected with the damping slider. The corrector comprises a fixed ring, a correction damper, a bearing, an inner ring of a friction pair and an outer ring of a friction pair; the fixed ring is installed at the upper end and / or the lower end of the flywheel rotor, the outer wall of the fixed ring is circumferentially installed with the correction damper and the bearing, the bearing is sleeved to install the inner ring of the friction pair, and the inner ring of the friction pair is sleeved to install the outer ring of the friction pair; the bearing adopts a ball bearing, a needle bearing or a self-lubricating bearing. The motor assembly further comprises an upper motor, an upper motor rotor, a lower motor and a lower motor rotor; the upper motor and the lower motor are permanent magnet synchronous motors, and the permanent magnet materials of the permanent magnet synchronous motors are distributed in a cylindrical shape on the surfaces of the upper end and the lower end of the flywheel rotor. The upper motor is connected with the bottom of the upper flange, and the lower motor is connected with the bottom of the lower flange. The upper motor rotor and the lower motor rotor are interference press-fitted at the upper end and the lower end of the flywheel rotor, and the upper motor rotor and the lower motor rotor are sequentially press-fitted by a permanent magnet, a magnetic conductor and a magnetic shield. The upper motor and the lower motor are located on the same vertical line and are symmetrical to each other. The motor assembly further comprises a motor stator, the motor stator is isolated from the outside of the vacuum chamber, the core of the motor stator is closely connected with the upper flange or the lower flange, and a vacuum isolation plate is arranged between the flywheel rotor and the motor stator. The heat dissipation assembly comprises an upper flange air cooling channel and / or an upper flange cooling water cavity opened in the upper flange, and a lower flange air cooling channel and / or a lower flange cooling water cavity opened in the lower flange. The permanent magnetic bearing adopts an upper unloading magnetic bearing, and comprises a permanent magnetic outer ring, a magnetic shield ring and a permanent magnetic inner ring.

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