An energy storage flywheel system applying a coreless motor

Abstract

The present invention belongs to the technical field of energy storage flywheels, and particularly relates to an energy storage flywheel system applying a coreless motor, which includes a flywheel rotor. The flywheel rotor is respectively supported up and down by a permanent magnet unloaded bearing and a hydrodynamic bearing, and rotates and stores energy in a vacuum chamber with the permanent magnet unloaded bearing and the hydrodynamic bearing as the central axes. A motor assembly for providing power to the flywheel rotor is further provided in the vacuum chamber. In the present invention, the energy storage flywheel system adopts a vertical rotation structure, with a permanent magnet unloaded bearing at the upper end, a hydrodynamic bearing at the lower end, and a flywheel rotor in the middle. The flywheel rotor is located in the vacuum chamber to ensure the high rotational speed of the flywheel rotor. The present invention has made progress in the application of a coreless Halbach permanent magnet motor, rotor stability, and hydrodynamic bearings in energy storage flywheels. The energy storage flywheel system designed thereby has good performance, reliability, and economy, and can be widely applied in the market.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage flywheels, and particularly relates to an energy storage flywheel system applying a coreless motor. Background Art

[0002] The energy storage flywheel has the characteristics of green energy technology, is pollution-free to the environment, insensitive to environmental temperature changes, can be charged and discharged continuously in a short time and at high frequencies, and there are basically no restrictions on the number of charge and discharge times. During the life cycle, the performance is stable without decline, and it has a good development momentum in the applications of UPS and smart grid energy storage. At the same time, the energy storage flywheel system can be applied to wind power, solar power plants, etc., and can quickly filter and frequency modulate, enabling it to quickly access the power grid and greatly improving the utilization rate of green energy. The key technologies of the energy storage flywheel system are mainly bearing technology, rotor stability technology, and energy conversion device motor / generator.

[0003] Regarding the bearing problem, the standby loss of the energy storage flywheel is an important indicator to measure the efficiency of the energy storage flywheel system, and the wear of the bearing is the main loss. The current energy storage flywheel systems all adopt mechanical bearings, permanent magnet bearings, electromagnetic bearings, and hybrid bearings. The wear loss of mechanical bearings is significantly greater than other support methods, and the mechanical bearings have a short life under continuous working conditions. Currently, the energy storage flywheel systems tend to use non-contact bearings to support the rotation of the rotor, and the bearing types are permanent magnet bearings, electromagnetic bearings, and superconducting magnetic bearings. The electromagnetic bearing solves the problem of non-contact rotor support, but has a complex structure, high cost, and the electromagnetic field of the electromagnetic bearing will generate eddy currents in the rotating shaft made of soft magnetic materials, bringing the problem of high rotor temperature rise. At the same time, the electromagnetic bearing itself will also generate energy consumption during continuous operation.

[0004] Regarding the rotor stability problem, at present, the problems that the whole rotor will have difficult-to-eliminate low-frequency precession and other problems under the influence of the rotor residual unbalance amount and oil film oscillation have not been solved, which poses a hidden danger to the stable operation of the energy storage flywheel system, and thus the design goal of the energy storage flywheel to operate without maintenance for twenty years cannot be achieved.

[0005] Therefore, based on the above problems, designing an energy storage flywheel system with good performance, reliability, and economy has important practical significance. Summary of the Invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides an energy storage flywheel system applying a coreless motor. The present invention has made progress in the application of a coreless Halbach permanent magnet motor, rotor stability, and hydrodynamic bearings in the energy storage flywheel. The energy storage flywheel system designed thereby has good performance, reliability, and economy, and can be widely applied in the market.

[0007] The technical solution adopted by the present invention to solve this problem is as follows:

[0008] An energy storage flywheel system applying a coreless motor includes a flywheel rotor. The flywheel rotor is supported up and down by a permanent magnet unloaded bearing and a hydrodynamic bearing respectively, and rotates and stores energy around the permanent magnet unloaded bearing and the hydrodynamic bearing as the central axis in a vacuum chamber. A motor assembly for providing power to the flywheel rotor is further provided in the vacuum chamber, and the motor assembly is a coreless double-layer Halbach permanent magnet motor.

[0009] Preferably, the vacuum chamber is enclosed by an upper flange, an outer sleeve and a lower flange.

[0010] More preferably, the flywheel rotor is located in the vacuum chamber. The flywheel rotor is in the shape of a flat disc with protruding shafts at the upper and lower ends. The protruding shaft at the lower end of the flywheel rotor serves as the hydrodynamic bearing shaft, and a hydrodynamic bearing is installed at the shaft end of the hydrodynamic bearing shaft. An annular groove is formed on the end face of the system rotor.

[0011] More preferably, the number of the motor assemblies is at least one, and the motor assemblies are located outside the upper end and / or the lower end of the flywheel rotor.

[0012] More preferably, the motor assembly includes:

[0013] A motor stator, which includes a stator tray fixed on the upper flange / lower flange, a stator winding skeleton arranged annularly on the stator tray, a stator winding laid on the inner and outer circles of the stator winding skeleton and closely connected with the stator tray, and a motor stator housing covering the stator winding;

[0014] A motor rotor, which is of a double-layer structure. The motor rotor is embedded in the inner and outer surfaces of the annular groove of the flywheel rotor. The motor rotor includes a permanent magnet structure, a magnetic conductor structure and a magnetic isolation structure pressed in sequence in a direction away from the motor stator.

[0015] More preferably, the permanent magnet structure is an annular permanent magnet composed of permanent magnet sheets with different magnetization directions. The permanent magnet structure includes multiple layers of permanent magnet rings arranged up and down. The permanent magnet rings are composed of permanent magnet sheets, and a permanent magnet sheet isolation ring is installed between the adjacent upper and lower layers of permanent magnet rings.

[0016] More preferably, the permanent magnet sheet includes one or more of a tile-shaped permanent magnet sheet and a triangular permanent magnet sheet.

[0017] More preferably, the permanent magnet unloaded bearing is divided into a stationary permanent magnet and a rotating permanent magnet. The stationary permanent magnet is in a circular columnar structure, and the rotating permanent magnet is fixed on the upper end of the flywheel rotor.

[0018] Further preferably, the hydrodynamic bearing includes a damper, and the damper includes a shaft socket, a damping body, a damping housing, damping oil, a damping support, and a damping spring. The damping spring is located at the upper end of the damping body and is evenly distributed in the circumferential direction between the damping body and the damping housing. The shaft socket is press-fitted into the center of the damping body with an interference fit, and the end of the hydrodynamic bearing shaft is located within the shaft socket.

[0019] Further preferably, it further includes a heat dissipation component, which includes:

[0020] A flange heat dissipation structure, which includes a circulating water cavity and / or an air-cooling channel opened on the upper flange and / or the lower flange;

[0021] An outer sleeve heat dissipation structure, which includes an outer cylinder water jacket formed on the outer wall of the outer sleeve;

[0022] An air-cooling port, which is an opening formed on the motor tray and corresponding to the position of the stator winding skeleton, and the air-cooling port forms a forced air-cooling channel.

[0023] Further preferably, an isolation sleeve is also provided between the motor stator and the motor rotor. Through the isolation sleeve, the motor stator is isolated outside the vacuum chamber. At the same time, heat conduction air ducts can be designed on the inner and outer double-ring surfaces, and a forced air-cooling fan is arranged at the bottom, so that the heat of the motor / generator is dissipated through air-cooling and an air-cooling fin radiator.

[0024] The advantages and positive effects of the present invention are:

[0025] 1. By applying the hydrodynamic bearing and the damper in the present invention, the bearing loss of the system can be greatly reduced, and it has good dynamic stability, avoiding the wear of mechanical bearings and the complex control and electromagnetic power consumption of active magnetic bearings.

[0026] 2. In the present invention, the flywheel rotor is of a flat structure, and an isotropic high-strength steel is used to make the flywheel rotor, avoiding the inherent defect that the circumferential tensile strength of the composite material rotor is high and the radial tensile strength is low, and ensuring the stable operation of the flywheel rotor.

[0027] 3. The present invention uses a coreless Halbach permanent magnet synchronous motor. The permanent magnet material rotor is integrated on the inner and outer circular ring surfaces of the annular groove inside the energy storage flywheel rotor. The stator winding of the motor is inserted between the double-layer permanent magnet structures. The motor rotor uses permanent magnet material, and there is no current inside the rotor, thus avoiding the eddy current loss of the induction motor rotor. At the same time, there is no copper loss or iron loss, and the rotor generates little heat.

[0028] 4. The upper part of the flywheel rotor of the present invention uses a permanent magnet bearing, and the lower part uses a hydrodynamic oil film bearing for the energy storage flywheel system. The hydrodynamic bearing is connected to the damping system. Once the rotor experiences low-frequency precession in the conical pendulum mode, oscillations caused by an extremely large current, or oscillations caused by external interference, etc., they can all be quickly dissipated through the damping system, basically solving the problem of low-frequency precession of the rotor system, and achieving extremely high rotor dynamic stability.

[0029] 5. The present invention can adopt forced air cooling, circulating water cooling, or hybrid cooling methods for heat dissipation to achieve the purpose of quickly dissipating heat.

[0030] 6. As the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0031] (1) The expected benefits and commercial value after the transformation of the technical solution of the present invention are: The present invention realizes the unity of economy and reliability, can be widely applied to markets such as UPS, wind power, solar energy, smart grid, rail transit, etc., and can achieve economic benefits of up to billions.

[0032] (2) The technical solution of the present invention fills the technical gaps at home and abroad in the industry: In the high-speed rotation of a rotor with an extremely large mass, the successful realization of stable operation without a critical point is achieved, and at the same time, it has excellent seismic performance. The hydrodynamic bearing is successfully applied to a rotor with an extremely large mass. Compared with general electromagnetic bearings, mechanical bearings, etc., it has a simple structure, more stable operation, and an extremely long service life, with almost no frictional loss.

[0033] (3) Whether the technical solution of the present invention solves the technical problems that people have been eager to solve but have never succeeded in: The hydrodynamic bearing is a light-load bearing. Dai Xingjian of Tsinghua University believes in a relevant report that the axial bearing capacity is generally less than 10 kg. Through calculation and experiment, the present invention has successfully realized a hydrodynamic bearing with a load of up to 100 kg, which is applied to a flywheel system with a rotor mass of more than 1 t.

[0034] (4) Whether the technical solution of the present invention overcomes the technical prejudice: The application of the hydrodynamic bearing overcomes the prejudice that the hydrodynamic bearing is only a light-load bearing and cannot be applied to a large-mass flywheel system. The double-layer Halbach coreless permanent magnet motor and the combined application of multiple units achieve high power of the coreless motor and extremely high power output of a single flywheel, enabling the application of the flywheel system in a high-power system. Description of the Drawings

[0035] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. However, it should be noted that these drawings are only designed for explanatory purposes and thus do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0036] Figure 1 is the overall structural diagram of the energy storage flywheel system of the present invention;

[0037] Figure 2 is the cross-sectional structural schematic diagram of the motor assembly;

[0038] Figure 3 is the cross-sectional structural schematic diagram of the damper.

[0039] In the figure: 1, permanent magnet unloading bearing; 2, upper flange; 3, flywheel rotor; 4, motor assembly; 4-1, motor stator winding; 4-2, stator winding housing; 4-3, stator winding skeleton; 4-4, rotor permanent magnet piece; 4-5, permanent magnet piece isolation ring; 4-6, magnetic conductor; 4-7, magnetic isolation body; 4-8, stator tray; 4-9, air cooling port; 5, outer sleeve; 5-1, outer cylinder water jacket; 6, lower flange; 6-1, flange water cavity; 7, damper; 7-1, shaft socket; 7-2, damper body; 7-3, damper housing; 7-4, damper oil; 7-5, damper support; 7-6, damper spring. Specific embodiments

[0040] First of all, it should be noted that the following will specifically illustrate the specific structure, characteristics and advantages of the present invention by way of examples. However, all the descriptions are only for the purpose of explanation and should not be construed as any limitation to the present invention. In addition, any single technical feature described or implied in each of the embodiments mentioned herein, or any single technical feature shown or implied in each of the drawings, can still be arbitrarily combined or deleted between these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned herein. In addition, for the sake of simplifying the drawings, the same or similar technical features may only be marked in one place in the same drawing.

[0041] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", "swivel connection", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The present invention will be specifically described below with reference to the accompanying drawings.

[0042] Embodiment 1 - An embodiment for overall structure description:

[0043] An energy storage flywheel system applying a coreless motor includes a flywheel rotor 3. The flywheel rotor 3 is supported up and down by a permanent magnet unloading bearing 1 and a hydrodynamic bearing respectively, and rotates and stores energy around the permanent magnet unloading bearing 1 and the hydrodynamic bearing as the central axis in a vacuum chamber. The vacuum chamber is also provided with a motor assembly 4 for providing power to the flywheel rotor 3. The motor assembly 4 is a coreless double-layer Halbach permanent magnet motor. The vacuum chamber is enclosed by an upper flange 2, an outer sleeve 5, and a lower flange 6.

[0044] In this embodiment, as Figure 1 shown, the upper and lower flanges and the outer sleeve form the vacuum chamber. The energy storage flywheel system adopts a vertical rotation structure. The upper end is a permanent magnet unloading bearing 1, the lower end is a hydrodynamic bearing, and the middle is a flywheel rotor 3. The flywheel rotor 3 is located in the vacuum chamber to ensure the high rotational speed of the flywheel rotor 3, thereby establishing an energy storage flywheel with a simple structure, stable performance, and good economy. The motor assembly 4 is a combined coreless Halbach permanent magnet motor, which provides power to the flywheel rotor 3. The flywheel system electric / generator adopts a coreless Halbach permanent magnet motor, and the hydrodynamic bearing is connected to an orifice plate damper, making the system have extremely high rotor dynamic stability. The application of the combined coreless Halbach permanent magnet motor realizes a high-power energy storage flywheel system. At the same time, different numbers of motors in combination can achieve different powers for the same flywheel system, and thus are applicable to different application scenarios. For example: In the present invention, 1 to 4 motor assemblies can be installed on one flywheel rotor to achieve a power of up to 100×4, that is, 400 kW. The combined motor can achieve powers of 100, 200, and 400 kW for a single flywheel; the application of the hydrodynamic bearing and the damper can greatly reduce the bearing loss of the system and have good dynamic stability, avoiding the wear of mechanical bearings and the complex control and electromagnetic power consumption of active magnetic bearings. At this time, the flywheel has quite good stability and energy density.

[0045] Embodiment 2 - An embodiment for flywheel rotor structure description:

[0046] The flywheel rotor 3 is located in a vacuum chamber. The flywheel rotor 3 is in the shape of a flat disc with protruding shafts at its upper and lower ends. The protruding shafts can be integrated with the rotor or assembled separately. The protruding shaft at the lower end of the flywheel rotor 3 serves as the hydrodynamic bearing shaft, and a hydrodynamic bearing is installed at the spherical end of the hydrodynamic bearing shaft. An annular groove is provided on the end face of the system rotor 3. Specifically, the flywheel rotor has a flat structure, and the ratio of its polar moment of inertia to its equatorial moment of inertia is not less than The flywheel rotor is made of isotropic high-strength steel to avoid the inherent defect that the circumferential tensile strength of a composite rotor is high while the radial tensile strength is low, ensuring the stable operation of the flywheel rotor. The material of the flywheel rotor is high-strength steel, and the required tensile strength of the material is greater than 1000 MPa; the rotor materials are generally 42CrMo, 42Cr, 4340, martensitic steel, etc. By optimizing the rotor dynamics of the flywheel rotor, a rotor system with a simple structure has extremely high dynamic stability, while improving the operation stability of the energy storage flywheel, the cost is also greatly reduced.

[0047] Example 3 - An example for explaining the structure of a coreless Halbach permanent magnet motor:

[0048] The energy storage flywheel motor / generator (motor assembly) is located inside the flywheel rotor, providing the system with rotational power and power generation capacity.

[0049] The motor assembly 4 includes a motor stator. The motor stator includes a stator tray 4-8 fixed on the upper flange 2 / lower flange 6, stator winding skeletons 4-3 arranged annularly on the stator tray 4-8, stator windings 4-1 laid on the inner and outer circles of the stator winding skeletons 4-3 and closely connected to the stator tray 4-8, and a motor stator housing 4-2 covering the stator windings 4-1; as Figure 2 shown, the motor stator is composed of a motor stator winding 4-1, a stator winding housing 4-2, a stator winding skeleton 4-3, and a stator tray 4-8. The stator winding skeletons 4-3 are arranged annularly on the stator tray 4-8, with 10, 16, or 20 evenly distributed circumferentially. The skeleton material is selected from ceramics, copper, or aluminum alloy, or it can also be selected from bakelite, plastics, etc., but it is preferably made to have a certain heat conduction capacity, or directly a copper water pipe can be selected to form circulating water flow inside. The motor stator winding 4-1 is laid on the inner and outer circles of the stator winding skeletons 4-3 according to the design and is closely connected to the stator tray 4-8, and finally covered with the motor stator housing 4-2. The motor stator housing 4-2 can be closely attached to the stator winding 4-1 or kept at a gap from the stator winding 4-1. At the same time, an air-cooling port 4-9 is opened at the bottom of the motor tray 4-8 to form a forced air-cooling channel.

[0050] The motor assembly 4 further includes a motor rotor which is of a double-layer structure. The motor rotor is embedded in the inner and outer surfaces of the annular groove of the system rotor 3. The motor rotor includes a permanent magnet structure (permanent magnet), a magnetic conductor structure (magnetic conductor), and a magnetic isolation structure (magnetic isolator) which are press-fitted in sequence away from the motor stator. The permanent magnet material is a rare earth permanent magnet material, neodymium iron boron or samarium cobalt permanent magnet, and its shape is a circular ring, a sector, etc. The permanent magnet and the magnetic isolator are press-fitted together with an interference fit. The whole motor rotor and the flywheel rotor are press-fitted together with a large interference fit. The magnetic conductor material is 45#, 20#, 42CrMo, 42Cr, 4340, and martensitic steel, and its shape is an integral circular ring or a split circular ring; the magnetic isolator material is non-magnetic stainless steel, aluminum alloy, etc., such as 304, 6061. As Figure 1 shown, an annular groove is opened on the end face of the system rotor 3, and the motor rotor is embedded therein. The motor rotor and the flywheel rotor 3 are connected in an interference fit manner. As Figure 2 shown, the motor rotor includes rotor permanent magnet pieces 4-4, permanent magnet piece isolation rings 4-5, magnetic conductors 4-6, and magnetic isolators 4-7. The permanent magnet pieces are tile-shaped permanent magnet pieces, and a plurality of permanent magnet pieces with different magnetization directions form an annular permanent magnet. The magnetic field distribution of this annular permanent magnet is close to a sine wave. According to the actual design, the axially arranged permanent magnet rings can be composed of 1 layer, 2 layers or multiple layers. Generally, an isolation ring 4-5 is arranged between layers, or the isolation ring 4-5 can also not be arranged. The isolation ring material is selected from magnetic conductive materials, such as 20#, 45#, 4340, etc.; the shape of the isolation ring is a circular ring matching the permanent magnet ring, and the thickness is generally 4 or 5 mm, or it can also be a split circular ring. In order to reduce the influence of the isolation ring 4-5 on the permanent magnet on the surface of the motor rotor, the isolation ring can be designed into 2 parts, namely a magnetic conductive material isolation ring and a non-magnetic conductive material isolation ring. The non-magnetic conductive material isolation ring is located on the surface of the permanent magnet of the motor rotor, and at the same time, the non-magnetic conductive material isolation ring can also play a role in strengthening the permanent magnet of the motor rotor.

[0051] Furthermore, it can also be considered in this embodiment that the permanent magnet structure is an annular permanent magnet composed of permanent magnet pieces 4-4 with different magnetization directions. The permanent magnet structure includes multiple layers of permanent magnet rings arranged up and down. The permanent magnet rings are composed of permanent magnet pieces 4-4, and a permanent magnet piece isolation ring 4-5 is installed between the adjacent upper and lower layers of permanent magnet rings. Specifically: by opening annular grooves on the upper and lower ends of the flywheel rotor 3, a permanent magnet composed of tile-shaped magnetic pieces magnetized at different angles is embedded therein. The circumferential magnetic field distribution of the permanent magnet is close to a sine wave. The permanent magnet has 1 to 4 layers axially and double layers inside and outside radially, constituting a double-rotor ironless Halbach permanent magnet motor.

[0052] Furthermore, it can also be considered in this embodiment that the permanent magnet pieces 4-4 include one or more of tile-shaped permanent magnet pieces and triangular permanent magnet pieces. The magnetic field direction of the permanent magnet pieces is determined according to the Halbach principle; the annular structure can be composed of regular tile-shaped magnet pieces, or can be composed of tile-shaped magnet pieces and triangular magnet pieces; the function of the triangular magnet pieces is to enhance the magnetic field and provide the suction force between the tile-shaped magnet pieces, thereby simplifying the magnetic ring assembly process; the back surface of the triangular magnet pieces is a plane to ensure the fixed position of the annular magnet pieces without sliding. Taking this embodiment as an example, the permanent magnet structure is an annular structure composed of tile-shaped permanent magnet pieces.

[0053] In this embodiment, the number of the motor assemblies 4 is at least one, and the motor assemblies are located outside the upper end and / or the lower end of the flywheel rotor 3. Under the condition of ensuring the structural strength, the process is simplified and the system speed is increased. According to actual requirements, the number of annular grooves on the end face of the flywheel rotor 3 is generally 1 or 2, and the flywheel system corresponds to 1, 2 or 4 motor assemblies. To increase the power of a single flywheel system, 1, 2 or 4 motor assemblies can be combined.

[0054] It should be noted that: according to actual requirements, the motor rotor can also be located outside the flywheel rotor and connected to the flywheel rotor. Through structural and strength design, the flywheel rotor can achieve a higher speed at this time, and the system power is relatively increased.

[0055] The present invention uses a coreless Halbach permanent magnet synchronous motor, and the permanent magnet material rotor is integrated on the inner and outer circular ring surfaces of the annular groove inside the energy storage flywheel rotor 3. A magnetic conductor ring and a magnetic isolation ring are arranged between the permanent magnet material (permanent magnet) and the flywheel rotor. Specifically: the motor rotor magnetic steel is fixed on the inner and outer ring surfaces of the annular groove of the flywheel rotor, and the rotor body material and the magnetic isolation material are directly used to protect the magnetic steel in terms of strength, and the strength requirement for the magnetic conductor ring is greatly reduced. The shape of the motor rotor permanent magnet is fan-shaped, and the permanent magnet ring formed by the permanent magnet, the magnetic isolation material and the yoke is installed on the flywheel rotor by an interference fit.

[0056] The motor stator winding is inserted between the double-layer permanent magnet structures. The motor rotor uses permanent magnet materials, and there is no current inside the rotor, thus avoiding the eddy current loss of the induction motor rotor. At the same time, there is no copper loss and iron loss, and the rotor generates little heat. The inner wall of the vacuum chamber is blackened, which is beneficial to heat radiation. At the same time, a circulating water channel is arranged on the outer wall of the vacuum chamber sleeve, which can quickly radiate the heat of the rotor.

[0057] Furthermore, it can also be considered in this embodiment that to increase the flywheel speed or simplify the flywheel rotor processing technology, the motor can be located on the outer sides of the upper and lower ends of the flywheel rotor.

[0058] Furthermore, it can also be considered in this embodiment that a vacuum isolation plate is arranged between the flywheel rotor and the motor stator, and the material of the isolation plate is aluminum alloy, non-magnetic stainless steel, etc.

[0059] Example 4 - An example described as a hybrid bearing:

[0060] The hybrid bearing is composed of a permanent magnet unloading bearing and a hydrodynamic bearing. The hybrid bearing provides the axial force of the system and the 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 equivalent to that of the permanent magnet suspension bearing, enabling the system to have sufficient seismic resistance performance.

[0061] The permanent magnet unloading bearing 1 is divided into a stationary permanent magnet and a rotating permanent magnet. The stationary permanent magnet has an annular cylindrical structure. The rotating permanent magnet is fixed to the upper end of the flywheel rotor 3. The permanent magnet unloading bearing is of an annular structure and uses an axial N - S magnetic pole arrangement to unload the gravity of the rotor. Structures such as split permanent magnets and single permanent magnets can also be used to obtain a bearing capacity that can be accommodated by the lower hydrodynamic bearing. Double - ring or triple - ring structures inside and outside can also be adopted, with the magnetization direction being N - S alternating to improve the utilization rate of permanent magnet materials. Permanent magnet materials generally use neodymium iron boron, samarium cobalt, etc.

[0062] It should be noted that: The permanent magnet unloading bearing can adopt an active magnetic bearing to adjust the magnetic pulling force of the upper magnetic steel at any time to ensure the balance of the axial force of the system.

[0063] The hydrodynamic bearing includes a damper 7. The damper 7 includes a shaft socket 7 - 1, a damper body 7 - 2, a damper housing 7 - 3, damper oil 7 - 4, a damper support 7 - 5, and a damper spring 7 - 6. The damper spring 7 - 6 is located at the upper end of the damper body 7 - 2 and is evenly distributed circumferentially between the damper body 7 - 2 and the damper housing 7 - 3. The shaft socket 7 - 1 is press - fitted with interference in the center of the damper body 7 - 2. The shaft end of the hydrodynamic bearing is located inside the shaft socket 7 - 1. As Figure 3 shown, the damper is composed of a shaft socket 7 - 1, a damper body 7 - 2, a damper housing 7 - 3, damper oil 7 - 4, a damper support 7 - 5, and a damper spring 7 - 6. The damping characteristics are mainly generated by the damper support 7 - 5, the damper body 7 - 2, the damper spring 7 - 6, and the damper oil together. The damper support 7 - 6 can use structures such as cylindrical thin rods, cage - like structures, and leaf springs, and the materials used are alloy steel, copper rods, and copper foil sheets, etc.; The damper spring 7 - 6 is located at the upper end of the damper body 7 - 2, with 3 or 6 evenly distributed circumferentially, and the material is steel. The shaft socket 7 - 1 is located in the center of the damper body 7 - 2 and is connected by press - fitting with interference. The shaft end of the hydrodynamic bearing is located inside the shaft socket 7 - 1. The rotation vibration of the rotor 3 is transmitted to the damper body 7 - 2 through the bearing. The damper body 7 - 2 deflects under the combined action of the spring 7 - 6, the damper oil 7 - 4, and the support rod 7 - 5, thereby dissipating the rotor vibration.

[0064] In this embodiment, a low-cost permanent magnet unloading bearing and a hydrodynamic bearing are selected as the hybrid bearing. The standby loss of the energy storage flywheel is an important indicator to measure the efficiency of the energy storage flywheel system, and the wear of the bearing is the main loss.

[0065] Current energy storage flywheel systems all adopt mechanical bearings, permanent magnet bearings, electromagnetic bearings and hybrid bearings. The wear loss of mechanical bearings is significantly greater than other support methods, and the service life of mechanical bearings is short under continuous working conditions. At present, energy storage flywheel systems tend to use non-contact bearings to support the rotation of the rotor, and the bearing types are permanent magnet bearings, electromagnetic bearings, and superconducting magnetic bearings. The electromagnetic bearing solves the problem of non-contact rotor support, but it has a complex structure and high cost. Moreover, the electromagnetic field of the electromagnetic bearing will generate eddy currents in the rotating shaft made of soft magnetic materials, which brings the problem of high rotor temperature rise. At the same time, the electromagnetic bearing itself will also consume energy during continuous operation. Due to the limitation of ENSHAW’S THEOREM, the permanent magnet bearing can only maintain stability in one direction, either axially or radially, and cannot form a rotor support method with full permanent magnet suspension. Currently, it is only in the position of bearing auxiliary unloading. Superconducting magnetic bearings can only be seen in research papers and frontier basic research, and it is impossible to reach the practical stage in the short term. At present, NEDO in Japan is taking the technical route of a 100 kWh large superconducting magnetic bearing energy storage flywheel, but the actual energy storage is only 25 kWh, and it has not yet reached the engineering practical stage. The hydrodynamic oil film bearing belongs to a relatively special bearing. In the static state, it is a contact bearing, while in the operating state, an oil film will be generated between the bearing and the bearing housing, which greatly reduces the friction loss. Moreover, the connection between the bearing, the bearing housing and the oil film ensures the positioning of the flywheel rotor. Therefore, it also has the stable characteristics of mechanical bearings.

[0066] The bearing in this embodiment adopts a micro-power consumption rotor support method supported by a permanent magnet unloading bearing and a hydrodynamic bearing. Since the technology of the hydrodynamic oil film bearing is already very mature and there has been experience of maintenance-free operation for 20 consecutive years in related professional technical products, strong technical support can be obtained, avoiding unnecessary bearing life and reliability assessment risks.

[0067] Furthermore, considering the characteristics of the liquid hydrodynamic bearing, if the weight of the rotor of the present invention exceeds 1 t, the upper permanent magnetic unloading bearing provides the rotor with a magnetic pull of about 95% of the rotor weight, and the magnetic pull value is between 800 and 1000 kg, and the axial stiffness of the permanent magnetic bearing must be between 20 and 50 kg / mm, and the radial stiffness of the permanent magnetic bearing must be basically consistent with the damping stiffness of the system. Specifically: the structure of the permanent magnetic unloading bearing is divided into a stationary part and a rotating part. The stationary part is a circular cylindrical structure. According to the size of the geometric dimensions, it can be assembled in blocks. The material is generally neodymium iron boron, samarium cobalt, etc., while the rotating part is fixed to the upper end of the rotor. It can be assembled in blocks. The material is generally neodymium iron boron, samarium cobalt, etc.; the permanent magnetic unloading bearing assembly can be selected and assembled by the magnetic field uniformity method to ensure the surface magnetic field uniformity of the permanent magnetic bearing, and the general magnetic field non-uniformity is ≤5%. The circumferential structure and annular structure of the permanent magnetic unloading bearing adopt unidirectional magnetization, NS cross magnetization and Halbach magnetization.

[0068] It should be noted that the liquid hydrodynamic bearing should provide axial load-bearing capacity and radial stiffness suitable for the system. For this flywheel system, the weight of the high-strength steel rotor is generally around 1000kg, the load-bearing capacity of the hydrodynamic bearing is about 5% of the rotor weight, and the permanent magnet unloading bearing bears about 95% of the rotor weight.

[0069] Example 5 - Example as an illustration of flywheel rotor stability:

[0070] In this embodiment, the flywheel rotor 3 adopts a technical solution of upper permanent magnetic unloading bearing and lower liquid hydrodynamic bearing support. At present, the problem that the entire rotor will have low-frequency precession that is difficult to eliminate under the influence of the residual imbalance of the rotor and the oil film oscillation has not been solved, which poses a hidden danger to the stable operation of the energy storage flywheel system. As a result, the design goal of the energy storage flywheel to operate maintenance-free for twenty years cannot be achieved. In view of the above problems, the present invention has made progress in structural design through the analysis of the dynamic stability of the rotor system, basically solved the low-frequency precession problem of the rotor system, and obtained extremely high rotor dynamic stability. The energy storage flywheel system of the present invention uses permanent magnetic bearings on the upper part of the rotor and hydrodynamic oil film bearings on the lower part. The liquid hydrodynamic bearing is connected to the damping system. Once the rotor has low-frequency precession of the cone pendulum mode, oscillation caused by super-large current, oscillation caused by external interference, etc., they can all be quickly dissipated through the damping system.

[0071] The damper used in the present invention adopts an squeeze film damper. The hydrodynamic bearing axle socket 7-1 is fixed together with the damper body 7-2. The damper body 7-2 is connected to the damper housing 7-3 by means of springs, diaphragms, etc. The damper body 7-2 is immersed in the damping oil 7-4. The damping oil, the damper body, the damping housing, and the gap provide the damping required by the system. A squirrel-cage damping structure can also be used for the springs, etc. Springs, squirrel cages, etc. provide the damping radial stiffness. The hydrodynamic bearing axle socket and the damper body are generally fixed together with the damper body by interference fit, threads, etc. The material of the axle socket is wear-resistant materials such as artificial glass, gemstones, beryllium bronze, etc. The material of the damper body is aluminum alloy, steel, stainless steel, etc. The material of the diaphragm is copper plate, steel plate, etc.

[0072] It should be noted that: at the upper and lower ends of the flywheel rotor, a rotor upper and lower corrector can also be provided between the flywheel rotor and the stationary parts; the corrector is composed of wear-resistant materials, ball bearings, and damping devices; the wear-resistant materials are composed of copper, aluminum alloy, powder metallurgy, etc. to form a friction pair, and the damping device adopts rubber damping, wire damping, or can also adopt squeeze film damping.

[0073] Embodiment 6 - An embodiment for explaining the heat dissipation of the energy storage flywheel system:

[0074] In the present invention, the energy storage flywheel system further includes a heat dissipation component.

[0075] Furthermore, it can also be considered in this embodiment that the heat dissipation component includes a flange heat dissipation structure, which includes a flange water cavity (circulating water cavity) opened on the upper flange 2 and / or the lower flange 6, and / or an air-cooling channel. Taking this embodiment as an example, the motor stator is embedded in the upper and lower flanges, and the upper and lower flanges are provided with a circulating water cavity and an air-cooling channel, and heat dissipation can be carried out by forced air cooling, circulating water refrigeration, or mixed refrigeration methods.

[0076] Furthermore, it can also be considered in this embodiment that the heat dissipation component includes an outer sleeve heat dissipation structure, which includes an outer cylinder water jacket 5-1 formed on the outer wall of the outer sleeve. The outer wall of the vacuum chamber sleeve is provided with an outer cylinder water jacket as a circulating water channel, which can quickly radiate the heat of the rotor.

[0077] Furthermore, it can also be considered in this embodiment that the heat dissipation component includes an air-cooling port, which is an opening formed on the motor tray 4-8 and corresponding to the position of the stator winding skeleton 4-3. The motor tray is connected to the bottom plates of the upper and lower flanges, and the air-cooling port forms a forced air-cooling channel, thus constituting a good heat dissipation channel.

[0078] Furthermore, it can also be considered in this embodiment that an isolation sleeve is also provided between the motor stator and the motor rotor. The motor stator is isolated outside the vacuum chamber through the isolation sleeve. At the same time, heat conduction air ducts can be designed on the inner and outer double-ring surfaces, and a forced air-cooling fan is arranged at the bottom, so that the heat of the motor / generator is dissipated through air cooling and an air-cooled fin radiator.

[0079] It should be noted that since the motor stator is isolated outside the vacuum chamber, the motor stator can adopt air cooling, water cooling or hybrid cooling according to the actual working conditions of the flywheel.

[0080] Furthermore, in this embodiment, it can also be considered that the motor stator uses ceramic rods, aluminum alloy rods, or copper rods as the stator winding skeletons, or it can also use heat pipes as the stator winding skeletons, and the motor stator windings are closely laid on the stator winding skeletons.

[0081] Furthermore, in this embodiment, it can also be considered that the motor stator windings are inserted between the double-layer permanent magnet structures and isolated outside the vacuum chamber. Direct and effective heat dissipation methods can be adopted for heat dissipation, including forced air cooling and water cooling. Fins can also be designed on the upper and lower flanges to increase the heat dissipation area and efficiency.

[0082] Furthermore, in this embodiment, it can also be considered that in order to improve the heat dissipation efficiency and reduce the influence of the motor stator heating on the flywheel rotor, in the case of detailed design, a thin-walled ring sleeve structure can also be used to isolate the motor stator outside the vacuum chamber, and at the same time, forced air cooling measures are used to achieve the purpose of quickly dissipating heat. The housing material is made of aluminum alloy, non-magnetic stainless steel, etc.

[0083] Furthermore, in this embodiment, it can also be considered that the motor stator can also be provided with aluminum alloy rings on the inner and outer circles, specifically aluminum alloy inner and outer rings. The motor stator windings are located inside the inner and outer double rings to ensure the inner and outer shape dimensions and axial geometric tolerances of the ironless stator windings. At the same time, the aluminum alloy inner and outer rings provide another heat dissipation channel. Especially when angle air flow grooves are designed on the non-winding surfaces of the inner and outer rings and the flange water chambers are connected with cooling water, the heat dissipation effect is better.

[0084] The heat of the motor can be dissipated through the above flange heat dissipation structure, stator windings, stator winding skeletons, and inner and outer double rings.

[0085] Working principle: As Figure 1As shown in the figure, this energy storage flywheel system includes a permanent magnet unloading bearing 1, an upper flange 2, a rotor 3, a motor assembly 4, an outer sleeve 5, a lower flange 6, and a damper 7. Among them: A vacuum chamber is formed by the upper flange 2, the outer sleeve 5, and the lower flange 6. Alternatively, the housing of the motor assembly 4 can also be used as a component of the vacuum chamber. The rotor 3 is located inside the vacuum chamber, and the motor assembly 4 is fixed to the lower flange 6. The inner and outer surfaces of the annular groove of the flywheel rotor 3 are inlaid with the motor rotor, and a hydrodynamic bearing is installed inside the flywheel rotor to ensure that the ball end of the hydrodynamic bearing coincides with the centroid of the flywheel rotor 3. A permanent magnet is installed at the upper end of the flywheel rotor 3, forming a permanent magnet unloading bearing 1 with the permanent magnet on the outer surface of the upper flange. It is generally cylindrical in shape with a central hole; materials are generally selected from neodymium iron boron, samarium cobalt, ferrite, etc. The flywheel rotor 3 is supported by the permanent magnet unloading bearing 1 and the hydrodynamic bearing up and down. When the motor assembly 4 provides power, it rotates and stores energy around the axes of the permanent magnet unloading bearing 1 and the hydrodynamic bearing.

[0086] The above embodiments have described the present invention in detail, but the above content is only the preferred embodiment of the present invention and should not be considered as limiting the scope of implementation of the present invention. Any equivalent changes and improvements made within the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A energy storage flywheel system applying a coreless motor, comprising a flywheel rotor (3), characterized in that: The flywheel rotor (3) is supported above and below by a permanent magnet unloading bearing (1) and a hydrodynamic bearing respectively, and rotates and stores energy around the axes of the permanent magnet unloading bearing (1) and the hydrodynamic bearing in a vacuum chamber. An electric motor assembly (4) for providing power to the flywheel rotor (3) is also provided in the vacuum chamber, and the electric motor assembly (4) is a coreless double-layer Halbach permanent magnet motor; The flywheel rotor (3) is located in the vacuum chamber. The flywheel rotor (3) is in the shape of a flat disc with protruding shafts at the upper and lower ends. The protruding shaft at the lower end of the flywheel rotor (3) serves as the hydrodynamic bearing shaft, and a hydrodynamic bearing is installed at the shaft end of the hydrodynamic bearing shaft. An annular groove is formed on the end face of the flywheel rotor (3); The hydrodynamic bearing includes a damper (7). The damper (7) includes a shaft socket (7-1), a damper body (7-2), a damper housing (7-3), damper oil (7-4), a damper support (7-5), and a damper spring (7-6). The damper spring (7-6) is located at the upper end of the damper body (7-2) and is evenly distributed along the circumferential direction between the damper body (7-2) and the damper housing (7-3). The shaft socket (7-1) is press-fitted into the center of the damper body (7-2) with interference fit, and the shaft end of the hydrodynamic bearing shaft is located within the shaft socket (7-1).

2. The energy storage flywheel system applying a coreless motor according to claim 1, wherein: The vacuum chamber is enclosed by an upper flange (2), an outer sleeve (5), and a lower flange (6).

3. The energy storage flywheel system applying a coreless motor according to claim 1, characterized in that: The number of the electric motor assemblies is at least one, and the electric motor assemblies are located outside the upper end and / or outside the lower end of the flywheel rotor (3).

4. The energy storage flywheel system applying a coreless motor according to claim 3, wherein: The electric motor assembly (4) includes: An electric motor stator, which includes a stator tray (4-8) fixed on the upper flange (2) / lower flange (6), stator winding skeletons (4-3) arranged annularly on the stator tray (4-8), stator windings (4-1) laid on the inner and outer circles of the stator winding skeletons (4-3) and closely connected to the stator tray (4-8), and an electric motor stator housing (4-2) covering the stator windings (4-1); An electric motor rotor, which has a double-layer structure. The electric motor rotor is embedded in the inner and outer surfaces of the annular groove of the flywheel rotor (3). The electric motor rotor includes a permanent magnet structure, a magnetic conductor structure, and a magnetic isolation structure press-fitted in sequence in a direction away from the electric motor stator.

5. The energy storage flywheel system applying a coreless motor according to claim 4, wherein: The permanent magnet structure is an annular permanent magnet composed of permanent magnet sheets (4-4) with different magnetization directions. The permanent magnet structure includes multiple layers of permanent magnet rings arranged up and down. The permanent magnet rings are composed of permanent magnet sheets (4-4), and a permanent magnet sheet isolation ring (4-5) is installed between the adjacent upper and lower layers of permanent magnet rings.

6. The energy storage flywheel system using a coreless motor according to claim 5, wherein: The permanent magnet sheet (4-4) includes one or more of a tile-shaped permanent magnet sheet and a triangular permanent magnet sheet.

7. A flywheel energy storage system using a coreless motor according to any one of claims 1-6, characterized in that: The permanent magnet unloading bearing (1) is divided into a stationary permanent magnet and a rotating permanent magnet. The stationary permanent magnet has a circular cylindrical structure, and the rotating permanent magnet is fixed to the upper end of the flywheel rotor (3).

8. A flywheel energy storage system using a coreless motor according to any one of claims 4-6, characterized in that: It further includes a heat dissipation assembly, which includes: A flange heat dissipation structure, which includes a circulating water cavity and / or an air cooling channel opened on the upper flange (2) and / or the lower flange (6); An outer sleeve heat dissipation structure, which includes an outer cylinder water jacket formed on the outer wall of the outer sleeve (5); The air-cooling port is an opening formed in the stator tray (4-8) and corresponding to the position of the stator winding skeleton (4-3), and the air-cooling port forms a forced air-cooling channel.

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