Flywheel energy storage device heavy load electromagnetic bearing design and temperature field analysis method and system

Abstract

The invention relates to the technical field of flywheel energy storage, in particular to a flywheel energy storage device heavy load electromagnetic bearing design and temperature field analysis method and system. Obtaining radial and axial bearing demand parameters of the flywheel energy storage device; designing axial and radial electromagnetic bearing structures based on the bearing demand parameters, wherein the design content comprises the structural sizes of electromagnetic bearing stators and rotors and coil winding parameters; bidirectional coupling simulation analysis of an electromagnetic field and a temperature field is carried out on the electromagnetic bearing. A supporting scheme combining a radial electromagnetic bearing and an axial electromagnetic bearing is adopted, a natural air cooling heat dissipation mode is set, the convective heat transfer coefficient is reasonably determined, the bias current of the axial electromagnetic bearing is 2.5 A, and the control currents of a steady-state working point and a maximum load working point are 1.2 A and 2.5 A respectively; the maximum working current of the radial electromagnetic bearing is 6A, and the electromagnetic force and the current are in a good linear relationship within the coil current range of 2A to 4A; under the natural air cooling condition, the maximum temperature of the electromagnetic bearing during working is 74.5 DEG C, and the requirement for safe operation of a flywheel energy storage device is met.

Description

Technical Field

[0001] The present invention relates to the technical field of flywheel energy storage, and particularly to a design method and temperature field analysis method and system for a heavy-duty electromagnetic bearing of a flywheel energy storage device. Background Art

[0003] A flywheel energy storage device can convert clean energy such as wind energy and solar energy into mechanical energy for storage, and convert it into electrical energy for use through a power electronic conversion device when needed. This device has the characteristics of high energy storage density, large instantaneous power, fast charge and discharge speed, long service life, high energy conversion efficiency, etc., and is applicable to technical fields such as power peak regulation, distributed power systems, and uninterruptible power supplies. It is one of the most competitive and promising new generation of green energy storage technologies.

[0004] The support system of traditional flywheel energy storage systems generally uses mechanical bearings, but a large amount of frictional loss will occur during high-speed operation, resulting in a reduction in bearing life and an increase in maintenance frequency. To solve this problem, current research has gradually shifted to magnetic levitation support methods such as permanent magnet bearings, electromagnetic bearings, and hybrid magnetic bearings. However, with the development of flywheel energy storage technology towards high energy density and high power density, the bearing capacity of magnetic bearings has become the main limiting factor. In addition, the introduction of electromagnetic bearings will increase additional power losses such as coil copper loss and magnetic pole permeable ring iron loss, resulting in magnetic pole thermal strain and affecting the operation accuracy and reliability of the flywheel energy storage device. In the prior art, a unidirectional coupling analysis method of electromagnetic field and temperature field is mostly used, without considering the influence of temperature rise on material properties, and the calculation accuracy needs to be improved.

[0005] Therefore, it is urgent to develop a new type of heavy-duty electromagnetic bearing support system and conduct accurate temperature field analysis on it to improve the performance and reliability of the flywheel energy storage device. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the problem to be solved by the present invention is how the introduction of electromagnetic bearings increases additional power losses such as coil copper loss and magnetic pole permeable ring iron loss, resulting in magnetic pole thermal strain and affecting the operation accuracy and reliability of the flywheel energy storage device. In the prior art, a unidirectional coupling analysis method of electromagnetic field and temperature field is mostly used, without considering the influence of temperature rise on material properties, and the calculation accuracy needs to be improved.

[0008] To solve the above technical problems, the present invention provides the following technical solutions:

[0009] In the first aspect, an embodiment of the present invention provides a design method and temperature field analysis method for a heavy-duty electromagnetic bearing of a flywheel energy storage device, which includes obtaining radial and axial bearing requirement parameters of the flywheel energy storage device;

[0010] Based on the load demand parameters, design the axial and radial electromagnetic bearing structures, and the design includes the structural dimensions of the electromagnetic bearing stator and rotor and the coil winding parameters;

[0011] Conduct two-way coupled simulation analysis of the electromagnetic field and temperature field of the electromagnetic bearing.

[0012] As a preferred embodiment of the design and temperature field analysis method of the heavy-duty electromagnetic bearing of the flywheel energy storage device of the present invention, wherein: the design of the axial electromagnetic bearing structure includes: designing a U-shaped stator structure, the U-shaped stator structure includes an inner ring and an outer ring, and the areas of the inner ring and the outer ring facing the thrust disc are equal; designing the thrust disc so that its thickness is greater than the width of the inner ring; designing the unilateral air gap between the stator and the thrust disc.

[0013] As a preferred embodiment of the design and temperature field analysis method of the heavy-duty electromagnetic bearing of the flywheel energy storage device of the present invention, wherein: the design of the radial electromagnetic bearing structure includes: adopting an eight-pole electromagnetic bearing design scheme, and pressing the stator and rotor into shape with silicon steel sheets; setting a preset air gap between the stator and the rotor; designing the cross-sectional area of the magnetic poles between the stator and the rotor.

[0014] As a preferred embodiment of the design and temperature field analysis method of the heavy-duty electromagnetic bearing of the flywheel energy storage device of the present invention, wherein: the two-way coupled simulation analysis of the electromagnetic field and temperature field includes: using the electromagnetic loss as the heat source for temperature field calculation in the temperature field analysis; feeding back the temperature field analysis results to the electromagnetic field calculation to update the resistivity property of the material; setting the iterative calculation accuracy of the temperature field and repeating the calculation until the temperature field converges.

[0015] As a preferred embodiment of the design and temperature field analysis method of the heavy-duty electromagnetic bearing of the flywheel energy storage device of the present invention, wherein: it further includes: setting an auxiliary bearing protection system for the axial and radial electromagnetic bearings; determining the protection gap between the auxiliary bearing and the electromagnetic bearing; and using the auxiliary bearing to bear the weight of the rotor in the bearing shutdown state.

[0016] As a preferred embodiment of the design and temperature field analysis method of the heavy-duty electromagnetic bearing of the flywheel energy storage device of the present invention, wherein: it further includes: controlling the axial and radial electromagnetic bearings in a differential working mode; setting the initial parameters of the bias current and the control current; and dynamically adjusting the bearing capacity of the electromagnetic bearing by adjusting the bias current and the control current.

[0017] As a preferred embodiment of the design and temperature field analysis method of the heavy-duty electromagnetic bearing of the flywheel energy storage device of the present invention, wherein: it further includes: setting a natural air-cooled heat dissipation method; respectively determining the convective heat transfer coefficient between the magnetic poles and the air and the convective heat transfer coefficient between the coil windings and the air; and calculating the temperature field distribution based on the convective heat transfer coefficient.

[0018] In a second aspect, an embodiment of the present invention provides a design and temperature field analysis system for a heavy-duty electromagnetic bearing of a flywheel energy storage device, which includes a parameter acquisition module for acquiring the radial and axial load-bearing requirement parameters of the flywheel energy storage device;

[0019] a design module for designing the axial and radial electromagnetic bearing structures based on the load-bearing requirement parameters, where the design includes the structural dimensions of the electromagnetic bearing stator and rotor and the coil winding parameters;

[0020] a simulation analysis module for performing two-way coupled simulation analysis of the electromagnetic field and temperature field of the electromagnetic bearing.

[0021] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, where the memory stores a computer program, and: when the computer program instructions are executed by the processor, the steps of the method for designing and temperature field analysis of the heavy-duty electromagnetic bearing of the flywheel energy storage device as described in the first aspect of the present invention are implemented.

[0022] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, and: when the computer program instructions are executed by the processor, the steps of the method for designing and temperature field analysis of the heavy-duty electromagnetic bearing of the flywheel energy storage device as described in the first aspect of the present invention are implemented.

[0023] The beneficial effects of the present invention are as follows: The present invention designs a support system for a flywheel energy storage device, adopting a scheme combining radial and axial electromagnetic bearings. Finite element simulation analysis of the electromagnetic performance of the heavy-duty electromagnetic bearing is carried out, and the temperature field analysis of the two-way coupling of the electromagnetic field and temperature field is completed, and the key current parameters of the electromagnetic bearing at different working points are determined. Specifically, the bias current of the axial electromagnetic bearing is 2.5 A, and the control currents at the steady-state working point and the maximum load working point are 1.2 A and 2.5 A respectively; the maximum working current of the radial electromagnetic bearing is 6 A, and within the range of coil current from 2 A to 4 A, the electromagnetic force has a good linear relationship with the current.

[0024] The temperature distribution obtained by the magnetic-thermal two-way coupling analysis calculation is more in line with the actual situation. The maximum temperature during the operation of the electromagnetic bearing under natural air-cooling conditions is 74.5 °C, which meets the safe operation conditions of the flywheel energy storage device. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 Flow chart of the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0027] Figure 2 Computer equipment diagram of the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0028] Figure 3 Structural diagram of the support system of the flywheel energy storage device for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0029] Figure 4 Schematic diagram of the axial magnetic bearing structure of the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0030] Figure 5 Schematic diagram of the radial electromagnet structure of the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0031] Figure 6 Schematic diagram of the mesh division of the axial electromagnetic bearing of the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0032] Figure 7 Magnetic flux density cloud diagram of the axial electromagnetic bearing when the coil current is 5A for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0033] Figure 8 Line graph of the change of the axial electromagnetic force with the control current for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0034] Figure 9 Line graph of the change of the axial electromagnetic force with the air gap for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0035] Figure 10 Schematic diagram of the mesh division of the radial electromagnetic bearing of the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0036] Figure 11 Magnetic flux density cloud diagram of the radial electromagnetic bearing when the coil current is 6A for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0037] Figure 12 Line graph of the change of the electromagnetic force of the radial electromagnetic bearing with the current in the coil for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0038] Figure 13 Line graph of the change of the radial electromagnetic force with the air gap for the design of the heavy-duty electromagnetic bearing for a flywheel energy storage device and the temperature field analysis method

[0039] Figure 14 It is a flowchart of unidirectional and bidirectional magneto-thermal coupling analysis for the design of heavy-duty electromagnetic bearings of a flywheel energy storage device and the temperature field analysis method;

[0040] Figure 15 It is a comparison diagram of the bidirectional coupled temperature field of the electromagnetic bearing for the design of the heavy-duty electromagnetic bearing of the flywheel energy storage device and the temperature field analysis method. Specific embodiments

[0041] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0042] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0043] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or selectively exclusive embodiment with other embodiments.

[0044] Embodiment 1

[0045] Refer to Figures 1 - 2 , which is the first embodiment of the present invention. This embodiment provides a method for designing a heavy-duty electromagnetic bearing of a flywheel energy storage device and analyzing the temperature field, including:

[0046] S100: Obtain the radial and axial load-bearing requirement parameters of the flywheel energy storage device;

[0047] In the embodiments of the present application, the load-bearing requirement parameters mainly include: axial bearing capacity requirement parameters, radial bearing capacity requirement parameters, operating speed parameters, and temperature requirement parameters; the load-bearing requirement parameters are all design parameters obtained according to the working conditions requirements of the actual application scenario.

[0048] Specifically, the axial bearing capacity requirement parameters can be the static bearing capacity and dynamic bearing capacity requirements calculated according to the gravity and impact load of the flywheel energy storage device. The radial bearing capacity requirement parameters can be the radial bearing requirements calculated according to the centrifugal force and unbalanced force generated by the flywheel rotor during high-speed rotation. The operating speed parameters can be the rated speed and maximum speed requirements determined according to the power requirements of the energy storage system. The temperature requirement parameters can be the maximum allowable operating temperature and temperature rise limit values determined according to the material properties of each component.

[0049] In an alternative embodiment, the axial bearing capacity requirement parameter, radial bearing capacity requirement parameter, operating speed parameter, and temperature requirement parameter in the bearing requirement parameters can be any combination calculated by a preset parameter optimization model. For example, when the axial bearing capacity requirement parameter is calculated based on static loads, the temperature requirement parameter can be determined according to the heat generation analysis under dynamic operating conditions.

[0050] In an alternative embodiment, other parameter items can also be added or reduced to the bearing requirement parameters according to different design objectives. For example, when more refined control performance is required, a dynamic response parameter (i.e., the fifth type of parameter) can be added to improve the control accuracy of the electromagnetic bearing under transient operating conditions. In addition, in order to further enhance the adaptability of the design, an adaptive parameter compensation algorithm can also be introduced to dynamically adjust the basic parameters to ensure good bearing characteristics under various operating conditions.

[0051] In an alternative embodiment, if the design objective only focuses on the bearing capacity and has low requirements for temperature characteristics, the temperature requirement parameter can be omitted to simplify the design process. However, in this application, such parameters are still retained to ensure the comprehensiveness and reliability of the design.

[0052] It should be noted that the above parameter acquisition process uses a multi-dimensional analysis method based on actual operating conditions. First, according to the basic requirements of the flywheel energy storage device, such as rated power, energy storage capacity, etc., the initial parameter range is determined. Then, through means such as dynamic analysis and thermodynamic calculation, the specific values of each parameter are refined. Finally, through optimization iteration, the final set of design parameters is determined. This method not only ensures the accuracy of the parameters but also provides a reliable basis for subsequent structural design.

[0053] S200: Based on the bearing requirement parameters, design the axial and radial electromagnetic bearing structures, including the structural dimensions of the electromagnetic bearing stator and rotor and the coil winding parameters;

[0054] The design of the axial electromagnetic bearing structure includes: designing a U-shaped stator structure, where the U-shaped stator structure includes an inner ring and an outer ring, and the areas of the inner ring and the outer ring facing the thrust disk are equal; designing the thrust disk to have a thickness greater than the width of the inner ring; and designing the unilateral air gap between the stator and the thrust disk.

[0055] In the embodiment of this application, the design of the U-shaped stator structure includes the design of the inner ring and the outer ring; the areas of the inner ring and the outer ring facing the thrust disk are equal, and both are made of pure electrical iron DT4C material. The thickness of the thrust disk is greater than the width of the inner ring, and the air gap design needs to consider the actual machining and assembly accuracy.

[0056] In an alternative embodiment, the inner and outer rings of the U-shaped stator structure can adopt a segmented design, that is, the stator is divided into several segments along the circumferential direction, which can reduce eddy current losses and improve the dynamic performance of the bearing. At the same time, the segmented structure is also convenient for assembly and maintenance.

[0057] In an alternative embodiment, the thickness of the thrust disk can also be optimized according to the operating speed. For example, at high speeds, the thickness of the thrust disk can be appropriately increased to improve its stiffness and ensure dynamic characteristics. However, the moment of inertia of the rotor needs to be considered at the same time, and the weight should be minimized as much as possible under the premise of meeting the strength requirements.

[0058] It should be noted that the design of the U-shaped stator structure needs to consider multiple factors overall. The equal area of the inner and outer rings is to ensure the uniform distribution of magnetic force and avoid generating additional torques. The thickness of the thrust disk being greater than the width of the inner ring is to ensure sufficient magnetic conduction area and prevent magnetic circuit saturation. The design of the air gap needs to find a balance between control performance and processing cost.

[0059] S202: The design of the radial electromagnetic bearing structure includes: adopting an eight-pole electromagnetic bearing design scheme, pressing the stator and rotor into shape with silicon steel sheets; setting a preset air gap between the stator and the rotor; designing the cross-sectional area of the magnetic poles between the stator and the rotor.

[0060] In the embodiment of the present application, the selection of the eight-pole electromagnetic bearing structure is based on a comprehensive consideration of the bearing capacity requirement and control performance. The eight-pole structure has good decoupling characteristics and can provide a greater bearing capacity under the same volume. Pressing the stator and rotor into shape with silicon steel sheets can effectively reduce eddy current losses.

[0061] In an alternative embodiment, different types of silicon steel sheets can be selected for the radial electromagnetic bearing, such as B50A290, B35A300, etc., and selected according to the operating frequency and loss requirements. The lamination direction of the silicon steel sheets needs to be consistent with the magnetic field direction to obtain the best magnetic permeability. The lamination coefficient needs to be considered during pressing, usually controlled above 0.95 to ensure good magnetic circuit characteristics.

[0062] In an alternative embodiment, the pole column structure of the radial electromagnetic bearing can also adopt a variable cross-section design. For example, the pole area can be appropriately increased near the air gap, which can not only reduce magnetic leakage but also improve the bearing capacity. However, it is necessary to pay attention to controlling the change rate of the pole area to avoid generating magnetic field distortion.

[0063] It should be noted that the design process of the eight-pole radial electromagnetic bearing needs to consider multiple key parameters. Among them, the circumferential distribution of the pole columns should be uniform and symmetric, and enough space should be reserved between adjacent pole columns for installing coils. The radial height of the magnetic poles should ensure sufficient magnetic conduction ability and avoid magnetic circuit saturation. The design of the cross-sectional area needs to find a balance between bearing capacity and volume.

[0064] In the embodiments of the present application, the coil winding parameters are designed based on the load-bearing capacity requirements and control characteristics of the electromagnetic bearing. The number of turns of the coil directly affects the magnetic field strength, the wire diameter determines the current density, and the insulation class is related to the temperature rise control.

[0065] In an alternative embodiment, the copper wire of the coil winding can adopt different specifications, such as enameled wire with a diameter of 0.8 mm - 1.5 mm, which is selected according to the current density and heat dissipation conditions. When winding, attention should be paid to controlling the neatness and density of the winding to avoid local overheating.

[0066] In an alternative embodiment, the arrangement of the coil can also consider layer winding. By dividing the entire coil into multiple layers and adding an insulating layer between each layer, the heat dissipation conditions can be effectively improved and the insulation reliability can be enhanced. However, attention should be paid to controlling the overall height after layering to ensure that it does not affect the overall structure of the bearing.

[0067] It should be noted that the design of the coil winding should simultaneously meet the electromagnetic and thermodynamic requirements. The selection of the number of turns should consider the output capacity of the power amplifier, ensuring sufficient magnetic field strength without exceeding the voltage limit of the power amplifier. The selection of the wire diameter should be balanced between the resistance loss and the volume. Too thin a wire will increase the loss, and too thick a wire will occupy too much space.

[0068] S300: Conduct a two-way coupled simulation analysis of the electromagnetic field and temperature field of the electromagnetic bearing.

[0069] In the embodiments of the present application, the two-way coupled analysis of the electromagnetic field and temperature field is carried out using the finite element method. A three-dimensional model of the electromagnetic bearing is established in the Maxwell and Icepak modules, and the material parameters, boundary conditions, and solution settings are set.

[0070] In an alternative embodiment, different mesh generation strategies can be adopted for the simulation analysis. Denser meshes are used in key areas such as the air gap region and the pole edge to improve the calculation accuracy. While in other regions, the mesh size can be appropriately relaxed to improve the calculation efficiency.

[0071] In an alternative embodiment, the influence of structural stress can also be considered in the two-way coupled analysis. By importing the calculation results of the temperature field into the structural analysis module, the influence of thermal stress on the bearing performance is evaluated. This multi-physical field coupled analysis can more comprehensively predict the actual working state of the bearing.

[0072] It should be noted that the two-way coupled analysis is an iterative convergence process. First, the electromagnetic field calculation is carried out to obtain the loss distribution; then the loss is used as the heat source for the temperature field calculation; and then the temperature field results are fed back into the material parameters to update the electromagnetic calculation. This process needs to be repeated until the change amount of the temperature field is less than the set convergence criterion.

[0073] S301: The two-way coupled simulation analysis of the electromagnetic field and the temperature field includes: using the electromagnetic loss as the heat source for the temperature field calculation in the temperature field analysis; feeding back the results of the temperature field analysis to the electromagnetic field calculation to update the resistivity property of the material; setting the iterative calculation accuracy of the temperature field and repeating the calculation until the temperature field converges.

[0074] In the embodiment of the present application, the electromagnetic loss mainly includes two parts: copper loss and iron loss. The copper loss is generated by the current in the coil and is related to the current magnitude and the coil resistance; the iron loss includes eddy current loss and hysteresis loss and is related to the magnetic field strength and the operating frequency. These losses are used as the heat sources for the temperature field calculation.

[0075] In an alternative embodiment, the calculation methods of the copper loss and the iron loss can be optimized according to the actual working conditions. For example, when operating at high speed, an improved iron loss calculation model can be adopted to consider the influence of the rotating magnetic field; under the condition of large current, the non-linear influence of temperature on the coil resistance can be considered. In this way, the loss distribution under the actual working state can be predicted more accurately.

[0076] In an alternative embodiment, the time-varying characteristics can also be considered in the distribution of the heat source. By establishing loss models under different working cycles, the dynamic change process of the temperature field is analyzed. This is particularly meaningful for evaluating the temperature rise characteristics of the bearing under complex working conditions.

[0077] It should be noted that special attention needs to be paid to the setting of the boundary conditions in the treatment of the loss heat source. For the coil region, the main distribution characteristics of the heat source should be considered; for the iron core part, the influence of the laminated structure on heat conduction needs to be considered. In addition, the temperature-related characteristics of the material, such as resistivity, thermal conductivity, etc., need to be described by appropriate mathematical models.

[0078] S302: It also includes: setting the auxiliary bearing protection system for the axial and radial electromagnetic bearings; determining the protection gap between the auxiliary bearing and the electromagnetic bearing; and using the auxiliary bearing to bear the weight of the rotor in the bearing shutdown state.

[0079] In the embodiment of the present application, deep groove ball bearings are selected as the auxiliary bearings. The protection gap between the auxiliary bearing and the electromagnetic bearing needs to be smaller than the working gap of the electromagnetic bearing to ensure that the rotor can be taken over in time in case of emergency.

[0080] In an alternative embodiment, the installation method of the auxiliary bearing can adopt an elastic support structure. By adding elastic elements between the bearing seat and the frame, the impact force when the rotor drops onto the shaft can be alleviated. The stiffness of the elastic element needs to be carefully calculated to ensure both sufficient supporting force and no resonance of the system.

[0081] In an alternative embodiment, the protection system may further include an axial position monitoring device. By installing a displacement sensor to monitor the rotor position in real time, when an abnormal displacement is detected, protective measures are taken in a timely manner. This active protection mechanism can effectively reduce the wear of the auxiliary bearings.

[0082] It should be noted that the design of the auxiliary bearing system needs to consider multiple factors comprehensively. First is the setting of the protection gap. If the gap is too large, the impact force will increase when the rotor drops onto the shaft, and if the gap is too small, it may affect the normal operation of the electromagnetic bearing. Second is the load-bearing capacity of the auxiliary bearing, which needs to be able to withstand the rotor weight and possible dynamic loads. Finally is the life assessment, which needs to consider the usage frequency during normal start-stop and emergency situations.

[0083] S303: It also includes: controlling the axial and radial electromagnetic bearings in a differential working mode; setting the initial parameters of the bias current and the control current; and dynamically adjusting the bearing capacity of the electromagnetic bearing by adjusting the bias current and the control current.

[0084] In the embodiments of the present application, the differential working mode is achieved by two groups of symmetrically arranged electromagnets. In the axial electromagnetic bearing, the upper and lower groups of electromagnets control the thrust disk by adjusting their respective currents; in the radial electromagnetic bearing, the rotor is positioned by adjusting the currents of the electromagnets in the corresponding directions.

[0085] In an alternative embodiment, the setting of the bias current and the control current can adopt an adaptive algorithm. Dynamically adjust the magnitude of the bias current according to the actual working state, while ensuring the control performance, reduce the power consumption. For example, appropriately reduce the bias current under light load conditions and increase the bias current in a timely manner under heavy load conditions.

[0086] In an alternative embodiment, feedforward compensation can also be introduced into the current control. By establishing a relationship model between the rotor speed and the unbalanced force, the advance compensation for periodic disturbances is realized, and the dynamic response performance of the system is improved.

[0087] It should be noted that the implementation of the differential working mode requires precise current control. The magnitude of the bias current directly affects the stiffness characteristics of the bearing, while the response speed of the control current determines the dynamic performance of the system. Therefore, the design of the current controller needs to find a suitable balance between the steady-state accuracy and the dynamic response.

[0088] S304: It also includes: setting the natural air-cooled heat dissipation method; respectively determining the convective heat transfer coefficient between the magnetic pole and the air and the convective heat transfer coefficient between the coil winding and the air; and calculating the temperature field distribution based on the convective heat transfer coefficient.

[0089] Furthermore, the present embodiment also provides a design and temperature field analysis system for a heavy-duty electromagnetic bearing of a flywheel energy storage device, including,

[0090] A parameter acquisition module that acquires the radial and axial bearing requirement parameters of the flywheel energy storage device;

[0091] A design module that designs the axial and radial electromagnetic bearing structures based on the bearing requirement parameters, including the structural dimensions of the electromagnetic bearing stator and rotor and the coil winding parameters;

[0092] A simulation analysis module that performs two-way coupled simulation analysis of the electromagnetic field and temperature field of the electromagnetic bearing.

[0093] In summary, by setting the steps for designing the axial and radial electromagnetic bearing structures based on the bearing requirement parameters, the precise design and optimization of the bearing structure are achieved, effectively solving the problem of a large amount of frictional loss generated by traditional mechanical bearings during high-speed operation, and ultimately achieving the effect of improving the service life of the flywheel energy storage device.

[0094] By adopting the U-shaped stator structure design and the design step of equal inner and outer ring areas, the magnetic force distribution is made more uniform, avoiding the additional torque caused by uneven magnetic force in the traditional structure. At the same time, by designing the thickness of the thrust disk to be greater than the width of the inner ring, sufficient magnetic conduction area is ensured, effectively preventing magnetic circuit saturation, thereby improving the bearing capacity and operation stability of the bearing.

[0095] By adopting the eight-pole electromagnetic bearing design scheme and choosing the method of pressing and forming with silicon steel sheets, good decoupling characteristics are achieved, significantly reducing the eddy current loss, making the control method simpler, and solving the technical problems of complex control and large loss of traditional electromagnetic bearings.

[0096] By establishing a two-way coupled analysis method for the electromagnetic field and temperature field, taking the electromagnetic loss as the heat source for the temperature field analysis, and feeding back the temperature field analysis results to the electromagnetic field calculation, the accurate calculation of the influence of temperature on material properties is achieved, overcoming the defect of insufficient calculation accuracy of the unidirectional coupled analysis method in the existing technology, and making the temperature field analysis results more in line with the actual working conditions.

[0097] By setting up an auxiliary bearing protection system and a reasonable protection gap, the rotor weight can be reliably borne in the bearing shutdown state, effectively protecting the electromagnetic bearing and avoiding equipment damage that may be caused in emergency situations such as accidental power failure.

[0098] By adopting the differential working mode control and the method of dynamically adjusting the bias current and control current, the electromagnetic bearing can maintain good bearing characteristics under different working conditions, improving the dynamic response performance and control accuracy of the system.

[0099] By setting the natural air-cooling heat dissipation method and reasonably determining the convective heat transfer coefficient, the effective heat dissipation of the electromagnetic bearing is achieved, avoiding a complex forced cooling system, simplifying the system structure, and reducing the operation and maintenance costs.

[0100] Example 2

[0101] Reference Figure 2 - Figure 15 , which is the second embodiment of the present invention.

[0102] Design of the Support System for Flywheel Energy Storage Device

[0103] The support system for the flywheel energy storage device designed by the present invention is as Figure 3 shown, mainly composed of a flywheel body, auxiliary bearings, radial electromagnetic bearings, a motor, axial electromagnetic bearings, etc. It adopts a combination of radial electromagnetic bearings and axial electromagnetic bearings for support, and has the advantages of high rotational speed, no wear, no need for a lubrication system, low power consumption, and a built-in online vibration monitoring function.

[0104] Relying on the active vibration control technology, the electromagnetic bearings can achieve an extremely low vibration and noise level. For the electromagnetic bearing system, the mechanical part of the bearing itself does not require maintenance; only the electronic components (such as capacitors) need to be replaced every 7 - 8 years. Therefore, this system can significantly improve the performance of the flywheel energy storage device.

[0105] Design of Axial Electromagnetic Bearings

[0106] The typical structure of an axial electromagnetic bearing is as Figure 4 shown. There is an axial stator on each side of the left and right of the thrust disk, with a U-shaped cross-section, consisting of an inner and outer ring; when the coil is energized, the magnetic field lines pass through the inner ring, the thrust disk, reach the outer ring, and then return to the inner ring through the yoke. Therefore, when designing, the areas of the inner and outer rings facing the thrust disk should be equal, and the thickness of the thrust disk should exceed the width of the inner ring.

[0107] There are two aspects to the design requirements of the axial electromagnetic bearing: one is to be able to lift the load such as the rotating shaft from the static state to stable suspension; on the other hand, when in stable suspension, to cope with the disturbances during charge and discharge, the bearing capacity of the electromagnetic bearing should reach an overload of 1g. That is, the actual bearing capacity of the axial electromagnetic bearing needs to reach twice the load. According to the relevant parameter requirements of the flywheel energy storage device, the mass m 0 of its rotating shaft is designed to be 4000 kg. Therefore, the maximum bearing capacity of the axial electromagnetic bearing is designed as:

[0108] F zmax = 2m 0 g = 78400 N#(1)

[0109] It is proposed that the unilateral air gap g z between the stator and the thrust disk of the axial electromagnetic bearing is 0.5 mm, and the protection gap is 0.2 mm. Considering the requirements of strength and magnetic conductivity, the thrust disk and the axial stator are made of pure iron for electrical engineering DT4C, and the maximum magnetic flux density B m is taken as 1.2 T. The pole areas S sumIt can be obtained from formula (2):

[0110]

[0111] Among them, μ 0 is the magnetic permeability of air, μ 0 = 4π×10 -7 H / m.

[0112] Determine the remaining parameters based on the areas of the inner and outer ring magnetic poles. After the geometric dimensions are determined, the coil parameters also need to be considered, which are related to the current amplifier parameters and the air gap.

[0113] Assume the maximum working current i zmax = 5A, and the number of turns of the coil is:

[0114]

[0115] Take the current density as ρ = 6.5A / mm 2 , and the effective area of the copper wire is:

[0116]

[0117] The wire diameter d c of the copper wire can be obtained as 1.1mm. So far, the basic parameters of the axial magnetic bearing have been determined, and its design parameters are shown in Table 1.

[0118] Table 1 Design parameters of the axial electromagnetic bearing

[0119] Serial number Parameter symbol Name Parameter value Unit 1 dz0 Inner diameter of rotor 200 mm 2 dz Outer diameter of rotor 300 mm 3 Dz0 Inner diameter of stator 220.5 mm 4 Dz Outer diameter of stator 257.5 mm 5 h Magnetic pole height 23 mm 6 Az Inner and outer ring area 18891.3 mm2 7 c1 Inner ring width 47.5 mm 8 c2 Outer ring width 35.85 mm 9 b Thrust disk thickness 86.3 mm 10 <![CDATA[N z > Number of turns of coil 191

[0120] Design of the radial electromagnetic bearing

[0121] The structure of the radial electromagnetic bearing is as Figure 5 shown. This electromagnetic bearing is an eight-pole electromagnetic bearing, and the stator and rotor are made of silicon steel sheets, with good decoupling performance and a relatively simple control method.

[0122] During the actual operation of the flywheel energy storage device, the interference received radially is small. Assume the maximum interference force F rmax is 20000N, and the cross-sectional area S r of the magnetic poles of the radial electromagnetic bearing is:

[0123]

[0124] Among them, the maximum magnetic flux density B max of the silicon steel sheet is 1.2T.

[0125] Determine the remaining parameters based on the magnetic pole area. After the geometric dimensions are determined, the coil parameters also need to be considered. Assume the maximum working current i rmax = 6A, and the number of turns of the coil is

[0126]

[0127] The effective area of the copper wire is

[0128]

[0129] The wire diameter d of the copper wire can be obtained cr is 1.1 mm.

[0130] So far, the basic parameters of the axial magnetic bearing have been determined, and the design parameters are shown in Table 2.

[0131] Table 2 Design Parameters of the Radial Electromagnetic Bearing

[0132] Serial number Parameter symbol Name Parameter value Unit 1 dr0 Inner diameter of rotor 210 mm 2 dr Outer diameter of rotor 430 mm 3 Lr Rotor width 254 mm 4 Dr0 Inner diameter of stator 431 mm 5 Dr Outer diameter of stator 746 mm 6 Lr Stator width 250 mm 7 t Width of pole post 110 mm 8 Nr Number of turns of coil 124 mm

[0133] Performance Analysis of the Electromagnetic Bearing

[0134] Selecting appropriate coil current parameters is crucial for the design of the control system. To ensure the control performance of the electromagnetic bearing, on the one hand, it is necessary to ensure that when the coil reaches the maximum operating current, the magnetic flux density of the electromagnet is in the non-saturated state; on the other hand, the electromagnetic force and the current should have a good linear relationship at the steady-state operating point. In this section, the electromagnetic performance of the electromagnetic bearing is analyzed and studied.

[0135] Performance Analysis of the Axial Electromagnetic Bearing

[0136] The finite element mesh division of the axial electromagnetic bearing is as Figure 6 shown. Set the coil current to the maximum operating current of 5 A, and the magnetic flux density simulation results are as Figure 7 shown. After calculation by the field calculator, the magnetic flux density of the magnetic circuit is about 1.0 T, and the maximum magnetic flux density is 1.5 T.

[0137] The axial electromagnetic bearing adopts a differential working mode. For example, the coil current of the upper magnetic pole is the bias current plus the control current, and the coil current of the lower magnetic pole is the bias current minus the control current. The resultant force on the thrust disk is the difference between the electromagnetic forces of the upper and lower magnetic poles. In general engineering, the operating point current is taken near half of the maximum operating current. Set the bias current of the axial electromagnetic bearing to 2.5 A and the air gap to 0.5 mm, and use the finite element software to calculate the variation of the axial electromagnetic force with the control current. The results are as Figure 8 shown.

[0138] When operating statically, the electromagnetic force provided by the axial electromagnetic bearing is 39200 N. From Figure 7It can be seen that the control current corresponding to the static operating point is 1.2 A. At this time, the actual current of the upper magnetic pole is 3.7 A, and the actual current of the lower magnetic pole is 1.3 A. When the load is in a state of one-fold overload, the control current is 2.5 A, and the electromagnetic force generated by the axial electromagnet is 78,833 N. At this time, the actual coil current of the upper magnetic pole is 5 A, and the actual coil current of the lower magnetic pole is 0 A. The bearing capacity of the axial electromagnetic bearing meets the design requirements.

[0139] When the axial electromagnetic bearing stops working, the rotating shaft falls on the auxiliary bearing, resulting in an increase in the air gap to 0.7 mm. When restarting, the axial electromagnetic bearing should generate sufficient electromagnetic force to make the rotating shaft return to the steady-state operating point. Set the coil current to 5 A, and use the finite element software to calculate the variation of the axial electromagnetic force with the air gap. The results are as Figure 9 shown.

[0140] Figure 9 In it, when the working air gap is 0.7 mm, the magnitude of the electromagnetic force is 39,238 N, which meets the requirement for the rotating shaft to return to stability.

[0141] Performance analysis of the radial electromagnetic bearing

[0142] The finite element mesh division of the radial electromagnetic bearing is as Figure 10 shown. Set the coil current to the maximum working current of 6 A, and its magnetic flux density simulation results are as Figure 11 shown. After calculation by the field calculator, the magnetic flux density of the magnetic circuit is about 1.0 T, and the maximum magnetic flux density is 1.2 T.

[0143] The radial electromagnetic bearing also adopts a differential working mode. For example, the coil current in the positive direction of the X-axis is the bias current plus the control current, and the coil current in the negative direction of the X-axis is the bias current minus the control current. The difference in the electromagnetic force on the rotor is the resultant force in the X-axis direction. Take the current near half of the maximum working current as the working point current. Set its bias current to 3 A and the air gap to 0.5 mm, and use the finite element software to calculate the variation of the radial electromagnetic force with the control current, as Figure 12 shown.

[0144] The simulation results show that when the control current is 3 A, the electromagnetic force generated by the radial electromagnet is 31,283.3 N, which is greater than the set maximum interference force and meets the requirements. At this time, the actual coil current in the positive direction of the X-axis is 6 A, and the actual coil current in the negative direction of the X-axis is 0 A. In addition, when the current is 2 A to 4 A, the linear relationship between the electromagnetic force and the current is good.

[0145] The radial magnetic bearing is also protected by an auxiliary bearing, and the variation range of its air gap is 0.3 mm to 0.7 mm. Set the coil current to 6 A, and use the finite element software to calculate the variation of the radial electromagnetic force with the air gap. The results are as Figure 13 shown.

[0146] The simulation results show that when the coil current is 6 A and the air gap is 0.7 mm, the resultant radial electromagnetic force is 21,196 N, which is greater than the set maximum interference force, and the radial magnetic bearing meets the requirements.

[0147] Analysis of the Temperature Field of the Two-Way Coupling of the Electromagnetic Field and Temperature Field of the Magnetic Bearing

[0148] Excessive temperature rise of the magnetic bearing not only causes the magnetic poles to expand and deform, changing the air gap size, but also leads to damage to the insulating paint on the coils, causing short circuits, which in turn affects the safe operation of the flywheel energy storage device. Traditional temperature field analysis is one-way coupling, only introducing electromagnetic losses into the temperature field calculation and ignoring the influence of temperature rise on materials. Two-way coupling temperature field analysis not only introduces electromagnetic losses into the temperature field, but also feeds back the analysis results of the temperature field to the calculation of the electromagnetic field to update the initial temperature and material resistivity and other properties. In this section, the temperature field of the two-way coupling of the electromagnetic field and temperature field of the magnetic bearing is analyzed.

[0149] Analysis Conditions for the Two-Way Coupling of the Electromagnetic Field and Temperature Field

[0150] When there is current passing through the coil winding, the magnetic bearing will generate losses such as copper loss and iron loss, generating heat, and under the action of temperature difference, part of the heat is dissipated through thermal radiation and thermal convection with the surrounding air. The material of the coil winding is copper, and its resistivity increases with the increase of temperature, which in turn affects the resistance of the coil winding and causes changes in copper loss. Therefore, the premise of accurately calculating copper loss is to consider the influence of temperature on the winding resistance. The relationship between copper resistivity ρ and temperature t is:

[0151] ρ = ρ 0 (1 + αt)#(8)

[0152] In the formula: α is the temperature coefficient of copper, taking 0.0039 °C-1; ρ 0 is the copper resistivity at 22 °C, and its value is 1.72 Ωm.

[0153] The iron core loss generated in the stator and rotor of the axial magnetic bearing can be calculated by the following formula:

[0154]

[0155] In the formula, σ w is the eddy current loss coefficient of the stator and rotor iron core material. For industrial pure iron, take σ w = 1×10 -6 ; f w is the repetition magnetization frequency; d is the thickness of the silicon steel sheet, unit; V Fe is the total magnetization volume of the iron core, unit m 3 . σ h is the hysteresis coefficient of the iron core material.

[0156] Assume that the working speed of the flywheel energy storage is 8000 rpm, fw = 133 HZ, and the total core loss of the axial magnetic bearing stator and rotor is 17.8 W.

[0157] For the core loss of the radial magnetic levitation bearing, the finite element method can be used for calculation, which has higher accuracy compared with the empirical formula.

[0158] The boundary conditions of the temperature field analysis mainly include the heat transfer coefficient of the material. The heat dissipation method of the magnetic bearing is air cooling. The surface of the magnetic bearing in contact with the air is in a natural convection state. The heat transfer coefficient of different component surfaces is related to the air velocity, and its calculation formula is:

[0159]

[0160] In the formula: α 1 is the convective heat transfer coefficient of the surface; α 0 is the convective heat transfer coefficient of the surface of the heating object in still air. For the surface of pig iron and steel, α 0 is taken as 16.7 W / (m²·K). For the surface of copper coated with insulating paint, α 0 is taken as 13.3 W / (m²·K); k is the efficiency coefficient, taken as 0.5; v a is the air velocity near the surface, taken as 0.1 m / s. According to the analysis, the convective heat transfer coefficient between the magnetic pole and the air is 19.3 W / (m²·K), and the convective heat transfer coefficient between the coil winding and the air is 15.4 W / (m²·K).

[0161] The one-way and two-way coupling analysis process of the electromagnetic field and temperature field is as Figure 14 shown. The process of one-way coupling is to input the coil winding as a heat load using the electromagnetic simulation module of Maxwell, and the Icepak thermal simulation module calculates the temperature according to the heat load and the convective heat transfer conditions. Two-way coupling is based on one-way coupling, adding a Feedback feedback module, setting the iterative calculation accuracy of the temperature field to 5%, and the feedback module compares and judges the temperature simulation results with the previous simulation results, updating the initial temperature of the electromagnetic field calculation and the resistivity of the material. Recursively calculate until the temperature converges to complete the iteration.

[0162] Temperature field analysis

[0163] Set the unilateral air gap of the magnetic bearing to 0.5 mm, set the current of the upper magnetic pole coil of the axial magnetic bearing to 5 A, and the lower magnetic pole coil is not energized; set the current of the radial magnetic bearing coil to 6 A, and conduct a magneto-thermal two-way coupling steady-state temperature field analysis on the magnetic bearing. Its temperature distribution is as Figure 15 shown.

[0164] The heat distribution of the axial electromagnetic bearing is uneven, with higher temperatures on the inner side of the stator and the thrust disc. The maximum temperature is approximately 29.5°C. The rotor of the radial magnetic bearing has a higher temperature rise. The main reason is that when the rotor rotates at high speed, the eddy current loss generated by cutting the magnetic field is relatively high. In addition, the heat generated by the copper loss of the coil is transferred to the rotor through heat convection and heat conduction. The highest temperature appears in the part of the rotor close to the X-axis direction, reaching 74.5°C.

[0165] After analysis, the maximum temperatures of the axial and radial electromagnetic bearings are 29.4°C and 74.5°C respectively. The temperature rises of the electromagnetic bearings are all within the allowable operating temperature ranges of the coil windings, silicon steel sheets, and DT4C. Selecting the natural air-cooling method can ensure the safe operation of the flywheel energy storage device.

[0166] The present invention designs a support system for a flywheel energy storage device, adopting a scheme combining radial and axial electromagnetic bearings. Finite element simulation analysis of the electromagnetic performance of the heavy-duty electromagnetic bearing is carried out, and the temperature field analysis of the bidirectional coupling of the electromagnetic field and the temperature field is completed, and the key current parameters of the electromagnetic bearing at different working points are determined. Specifically, the bias current of the axial electromagnetic bearing is 2.5 A, and the control currents at the steady-state working point and the maximum load working point are 1.2 A and 2.5 A respectively; the maximum working current of the radial electromagnetic bearing is 6 A, and within the range of the coil current from 2 A to 4 A, the electromagnetic force has a good linear relationship with the current.

[0167] The temperature distribution obtained by the magneto-thermal bidirectional coupling analysis is more in line with the actual situation. The maximum temperature during the operation of the electromagnetic bearing under natural air-cooling conditions is 74.5°C, which meets the safe operation conditions of the flywheel energy storage device.

[0168] Embodiment 3

[0169] This embodiment also provides a computer device, which is applicable to the situation of a design and temperature field analysis method for a heavy-duty electromagnetic bearing of a flywheel energy storage device, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement a forced oscillation detection and positioning method for a distribution network as proposed in the above embodiment.

[0170] This embodiment also provides a storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements a forced oscillation detection and positioning method for a distribution network as proposed in the above embodiment.

[0171] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a carrier network, NFC (Near Field Communication), or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, a touchpad, or a mouse, etc.

[0172] If a function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The foregoing storage medium includes: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc that can store program codes.

[0173] The logic and / or steps represented in the flowchart or described in other ways herein, for example, can be considered as a definite sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch instructions from the instruction execution system, apparatus, or device and execute the instructions), or in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device.

[0174] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A design method for a heavy-load electromagnetic bearing of a flywheel energy storage device and a temperature field analysis method, characterized in that: Including, obtaining radial and axial load requirement parameters of the flywheel energy storage device; Based on the load demand parameters, designing axial and radial electromagnetic bearing structures, wherein the design includes electromagnetic bearing stator and rotor structure dimensions and coil winding parameters; A bidirectional coupling simulation analysis of the electromagnetic field and the temperature field is performed on the electromagnetic bearing.

2. The flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to claim 1, characterized in that: The design of the axial electromagnetic bearing structure includes: designing a U-shaped stator structure, the U-shaped stator structure includes an inner ring and an outer ring, wherein the areas of the inner ring and the outer ring facing the thrust plate are equal; designing the thrust plate so that its thickness is greater than the width of the inner ring; and designing a single-sided air gap between the stator and the thrust plate.

3. The flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to claim 2, characterized in that: The design of the radial electromagnetic bearing structure includes: adopting an eight-pole electromagnetic bearing design scheme, pressing the stator and the rotor into shape using silicon steel sheets; setting a preset air gap between the stator and the rotor; and designing the cross-sectional area of ​​the magnetic poles between the stator and the rotor.

4. The flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to claim 3, characterized in that: The bidirectional coupling simulation analysis of the electromagnetic field and the temperature field includes: taking the electromagnetic loss as the heat source of the temperature field analysis to perform temperature field calculation; feeding back the temperature field analysis results to the electromagnetic field calculation to update the resistivity properties of the material; setting the iterative calculation accuracy of the temperature field, and repeating the calculation until the temperature field converges.

5. The flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to claim 4, characterized in that: Also includes: Auxiliary bearing protection systems for axial and radial electromagnetic bearings are provided; a protection gap between the auxiliary bearings and the electromagnetic bearings is determined; and when the bearings are stopped, the auxiliary bearings are used to carry the weight of the rotor.

6. The flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to claim 5, characterized in that: Also includes: A differential working mode is adopted to control the axial and radial electromagnetic bearings; initial parameters of the bias current and the control current are set; and dynamic adjustment of the bearing capacity of the electromagnetic bearing is achieved by adjusting the bias current and the control current.

7. The flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to claim 6, characterized in that: Also includes: Set the natural air cooling mode; determine the convection heat transfer coefficient between the magnetic pole and the air and the convection heat transfer coefficient between the coil winding and the air respectively; The temperature field distribution is calculated based on the convective heat transfer coefficient.

8. A flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis system, based on the flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to any one of claims 1 to 7, characterized in that: It also includes a parameter acquisition module to obtain radial and axial load demand parameters of the flywheel energy storage device; A design module, based on the load demand parameters, designs axial and radial electromagnetic bearing structures, wherein the design includes electromagnetic bearing stator and rotor structure dimensions and coil winding parameters; The simulation analysis module performs bidirectional coupling simulation analysis of the electromagnetic field and the temperature field on the electromagnetic bearing.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the flywheel energy storage device heavy-duty electromagnetic bearing design and temperature field analysis method according to any one of claims 1 to 7 are implemented.

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