Flywheel energy storage motor stator and rotor structure and optimization method thereof

Abstract

The invention relates to the technical field of motors, and discloses a flywheel energy storage motor stator-rotor structure and an optimization method thereof, and the flywheel energy storage motor stator-rotor structure comprises a stator body, a rotor body and a motor air gap. The method further comprises the following steps: step 1, designing an air-gap magnetic field: by adjusting the shape and the arrangement mode of a motor air gap or a permanent magnet, enabling a flux density waveform to be close to a sine wave when the motor air gap is in a no-load state so as to suppress harmonic waves; step 2, slot-pole matching design: a stator winding adopts a fractional slot concentrated winding form, a high fundamental wave winding factor is obtained by adjusting the matching relation between stator slots and permanent magnet pole numbers, and specific subharmonics are suppressed from a winding magnetomotive force level; 3, magnetic circuit and structure design: magnetic circuit saturation is suppressed by adjusting the geometric dimensions of stator teeth and a yoke part; according to the invention, the comprehensive performance targets of high torque density, high efficiency and low torque pulsation of the flywheel motor can be realized at the same time.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a stator-rotor structure of a flywheel energy storage motor and its optimization method. Background Technology

[0002] Flywheel energy storage is an advanced physical energy storage technology that uses a high-speed rotating flywheel to store electrical energy in the form of kinetic energy, and then rapidly converts the kinetic energy back into electrical energy through a motor-generator set when needed. Compared with chemical battery energy storage, flywheel energy storage has outstanding advantages such as high power density, fast charging and discharging speed, extremely long cycle life (up to millions of times), wide operating temperature range, and environmental friendliness and pollution-free operation. Therefore, it shows great application potential in fields such as grid frequency regulation, uninterruptible power supplies (UPS), energy recovery in rail transit, renewable energy grid connection, and attitude control and energy management of space stations.

[0003] One of the core components of a flywheel energy storage system is the integrated motor / generator (hereinafter referred to as "flywheel motor"). This motor acts as a motor during charging, driving the flywheel to accelerate; and as a generator during discharging, it uses the flywheel's inertia to decelerate and generate electricity. The performance of the flywheel motor directly determines the energy conversion efficiency, response speed, power density, and operational stability of the entire energy storage system. To maximize the advantages of the flywheel energy storage system, the matching motor needs to have high efficiency, high power density, high torque density, low torque ripple, high reliability, and long lifespan.

[0004] Currently, permanent magnet synchronous motors (PMSMs), especially surface-mounted (SPMSM) and internally mounted (IPMSM) PMSMs, have become the preferred motor type for flywheel energy storage systems due to their inherent advantages of high efficiency and high power density. However, existing conventional PMSMs still face a series of technical bottlenecks when applied to ultra-high-speed flywheel systems: Firstly, regarding air gap magnetic field optimization, traditional motor designs often employ uniform air gaps and standard rectangular or tile-shaped permanent magnets. This structure generates an air gap magnetic flux density waveform rich in high-order harmonic components. These harmonics interact with stator current harmonics, becoming the primary source of torque pulsation. Simultaneously, the harmonic magnetic field induces additional eddy current and hysteresis losses in the stator core and rotor permanent magnets / shrouds. Especially at high fundamental frequencies (high speeds), these high-frequency harmonic losses increase dramatically, leading to severe motor overheating and a significant decrease in efficiency. While methods such as skewed poles or skewed slots can be used to weaken harmonics, skewed pole manufacturing is complex and reduces rotor dynamic balance accuracy; skewed slots increase copper losses and leakage inductance, offering limited effectiveness. Secondly, regarding slot-pole pairing, while conventional integer-slot concentrated winding or distributed winding designs are mature, they have shortcomings in harmonic suppression and winding end length. For example, some slot-pole pairing schemes may introduce large low-order tooth harmonics, which are difficult to completely eliminate by optimizing the magnetic poles, resulting in large cogging torque. On the other hand, traditional long-pitch distributed windings have excessively long end windings, which not only occupy a large amount of axial space and reduce the power density of the motor, but also increase copper loss and leakage inductance, which are detrimental to efficiency and dynamic response. Secondly, in terms of magnetic circuit design, in pursuit of high torque, designers often tend to increase the amount of permanent magnets and armature current, but this can easily lead to local magnetic saturation in the stator teeth and yoke. Magnetic circuit saturation not only limits the linear growth of torque, making the marginal effect of torque increase diminish, but also causes magnetic field waveform distortion, further worsening torque pulsation and increasing iron loss. In addition, for high-speed applications, the mechanical strength of the rotor structure is crucial. Traditional rotor designs may have problems with stress concentration or insufficient protection in terms of protecting permanent magnets and withstanding huge centrifugal forces, which limits the maximum operating speed of the flywheel.

[0005] In summary, existing flywheel motor design methods typically optimize one aspect in isolation, lacking a design concept and technical solution that systematically and synergistically optimizes the air gap magnetic field, slot-pole matching, and magnetic circuit structure. This piecemeal approach often results in neglecting other aspects and makes it difficult to simultaneously achieve the comprehensive performance goals of high torque density, high efficiency, and low torque ripple. Summary of the Invention

[0006] This invention provides a stator-rotor structure and optimization method for a flywheel energy storage motor. By deeply coupling and synergistically optimizing the three core aspects of the motor's electromagnetic scheme—the distribution of the air gap magnetic field between the stator and rotor, the matching relationship between the stator slots and the rotor poles, and the overall magnetic circuit structure—it solves the key problems mentioned in the background art, such as high harmonic content, large torque ripple, and limited power output, which exist in traditional flywheel motors.

[0007] This invention provides the following technical solution: A flywheel energy storage motor stator-rotor structure includes a stator body and a rotor body. The stator body includes a stator core with stator slots evenly spaced on it. Stator teeth are formed between adjacent sets of stator slots. A slot opening is formed on the side of the stator slot near the inner wall of the stator core. A shoe-shaped portion is formed on the side of the inner wall of the stator core near the stator slot and slot opening. A yoke is formed between the stator slot and the outer wall of the stator core. A stator winding is wound between adjacent sets of stator slots. The rotor body includes a rotor core rotatably connected to the interior of the stator core. Multiple sets of permanent magnets are inserted inside the rotor core. A protective structure is inserted on the side of the rotor core near the permanent magnets, and the protective structure abuts against the permanent magnets. The structure also includes a motor air gap formed between the inner wall of the stator core and the outer wall of the rotor core.

[0008] As a preferred embodiment of the present invention, the stator core or rotor core is made of silicon steel, alloy steel, amorphous alloy or maraging steel to reduce high-frequency loss.

[0009] As a preferred embodiment of the present invention, the protective structure is made of glass fiber composite material, non-magnetic alloy material, carbon fiber or carbon fiber composite material to withstand high-speed centrifugal force. When the motor is a surface-mounted permanent magnet motor, the protective structure is a sheath made of carbon fiber composite material, glass fiber composite material or non-magnetic alloy material.

[0010] An optimization method for the stator-rotor structure of a flywheel energy storage motor, wherein the motor structure is formed by at least two of the following designs, including the following steps: Step 1: Air gap magnetic field design: By adjusting the shape and arrangement of the motor air gap or permanent magnet, the magnetic flux density waveform of the motor air gap when unloaded is made close to a sine wave to suppress harmonics; Step 2: Slot-pole matching design: The stator winding adopts a fractional slot concentrated winding form. By adjusting the matching relationship between the stator slots and the number of permanent magnet poles, a high fundamental frequency winding factor is obtained, and specific harmonics are suppressed from the winding magnetomotive force level. Step 3: Magnetic circuit and structural design: Suppress magnetic circuit saturation by adjusting the geometry of the stator teeth and yoke.

[0011] As a preferred technical solution of the present invention, in step one, the air gap of the motor is designed as a non-uniform air gap, the length of the air gap is a preset value in the direction of the center line of each pole, and increases smoothly in the direction of the circumference towards the edge of the magnetic pole according to a preset function, the preset function being a parabolic function or a cosine function.

[0012] As a preferred technical solution of the present invention, in step one, the permanent magnet is shaped like a "bread slice" and the surface facing the air gap of the motor is a raised arc surface.

[0013] As a preferred technical solution of the present invention, in step one, the permanent magnets are arranged in a segmented combination, in a V-shape, W-shape or Halbach array arrangement.

[0014] As a preferred technical solution of the present invention, in step two, the combination of the number of stator slots and the number of permanent magnet poles includes twelve slots with ten poles, twenty-four slots with twenty-two poles, or eighteen slots with sixteen poles.

[0015] As a preferred technical solution of the present invention, in step three, when the motor is a built-in permanent magnet motor, a magnetic bridge for fixing the permanent magnet is provided in the rotor core. By adjusting the shape and thickness of the magnetic bridge, the magnetic circuit isolation is ensured while meeting the mechanical strength requirements under high-speed operation.

[0016] As a preferred technical solution of the present invention, step three includes an auxiliary harmonic suppression structure, which is an auxiliary groove formed on the top of the stator teeth or a wave suppression groove formed on the surface of the permanent magnet.

[0017] Compared with the prior art, the present invention provides a stator-rotor structure of a flywheel energy storage motor and its optimization method, which has the following beneficial effects: In the stator-rotor structure of this flywheel energy storage motor, by deeply coupling and synergistically optimizing the three core aspects of the motor's electromagnetic scheme—the distribution of the air gap magnetic field between the stator and rotor, the matching relationship between the stator slots and the rotor poles, and the overall magnetic circuit structure—the comprehensive performance goals of high torque density, high efficiency, and low torque pulsation of the flywheel motor are achieved.

[0018] The parts of the device not described herein are the same as or can be implemented using existing technologies. This invention can simultaneously achieve the comprehensive performance goals of high torque density, high efficiency and low torque ripple of flywheel motors. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to actual scale.

[0020] Figure 1 This is a three-dimensional structural diagram of the stator and rotor structure of a flywheel energy storage motor proposed in this invention; Figure 2 This is a partial cross-sectional structural diagram of the stator and rotor structure of a flywheel energy storage motor proposed in this invention; Figure 3 This is a flowchart of an optimization method for the stator and rotor structure of a flywheel energy storage motor proposed in this invention.

[0021] In the diagram: 1. Stator body; 11. Stator core; 12. Stator teeth; 13. Stator slot; 14. Shoe part; 15. Yoke part; 16. Slot opening; 17. Stator winding; 2. Rotor body; 21. Rotor core; 22. Permanent magnet; 23. Protective structure; 3. Motor air gap. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: Reference Figures 1-2 A flywheel energy storage motor stator-rotor structure includes a stator body 1 and a rotor body 2. The stator body 1 includes a stator core 11, on which stator slots 13 are evenly distributed. Stator teeth 12 are formed between adjacent sets of stator slots 13. A slot opening 16 is formed on the side of the stator slot 13 near the inner wall of the stator core 11. A shoe portion 14 is formed on the side of the inner wall of the stator core 11 near the stator slots 13 and the slot opening 16. A yoke portion 15 is formed between the stator slots 13 and the outer wall of the stator core 11. A stator winding 17 is wound between adjacent sets of stator slots 13. The rotor body 2 includes a rotor core 21. The rotor core 21 is rotatably connected to the inside of the stator core 11. Multiple sets of permanent magnets 22 are inserted inside the rotor core 21. A protective structure 23 is inserted on the side of the rotor core 21 near the permanent magnets 22. The protective structure 23 abuts against the permanent magnets 22. The rotor core 21 also includes a motor air gap 3, which is formed between the inner wall of the stator core 11 and the outer wall of the rotor core 21. The stator core 11 or the rotor core 21 is made of silicon steel, alloy steel, amorphous alloy or maraging steel to reduce high frequency loss. The protective structure 23 is made of glass fiber composite material, non-magnetic alloy material, carbon fiber or carbon fiber composite material to withstand high-speed centrifugal force.

[0024] Example 2: Similar to Embodiment 1, an optimization method for the stator-rotor structure of a flywheel energy storage motor is proposed based on Embodiment 1. The motor structure is formed by at least two designs, including the following steps: Step 1: Air gap magnetic field design: By adjusting the shape and arrangement of the motor air gap 3 or permanent magnet 22, the magnetic flux density waveform of the motor air gap 3 when unloaded is made close to a sine wave to suppress harmonics; In order to reduce harmonic content at the source, this invention asymmetrically modifies the distribution of air gap permeability and magnetomotive force to obtain an air gap magnetic field that is close to an ideal sine wave. In step one, the air gap 3 of the motor is designed as a non-uniform air gap. The non-uniform air gap design is as follows: the air gap between the inner side of the stator core 11 and the outer side of the rotor core 21 is designed as a non-uniform shape. Specifically, the air gap length is the smallest in the direction of the center line (d-axis) of each magnetic pole; when transitioning from the center line to the edge of the magnetic pole (q-axis), the air gap length increases smoothly according to a preset function (such as a parabolic function or a cosine function). This design makes the air gap magnetic permeability quasi-sine distributed along the circumference, which can effectively weaken the high-order harmonics in the dense waveform of the air gap, especially having a significant effect on suppressing tooth harmonics and pulsating torque. Optimization and segmented combination of permanent magnet 22 shape: Abandoning the traditional rectangular or tile shape, one or more optimized shapes are adopted. For example, the shape of permanent magnet 22 is designed as a "bread slice", that is, the side facing the motor air gap 3 is a convex arc shape, which can make the magnetic field lines more evenly distributed. Furthermore, permanent magnet 22 is arranged in segments, such as in a V-shape, W-shape or Halbach array. For example, the V-shape arrangement can improve the fundamental magnetic flux density amplitude through the magnetic field focusing effect and increase the torque. By using multiple permanent magnets 22 of different widths or thicknesses to splice along the circumference and adjusting the magnetization direction of each segment of magnet, a highly sinusoidal magnetomotive force waveform can be precisely constructed, thereby greatly suppressing harmonics.

[0025] Step 2: Slot-pole matching design: The stator winding 17 adopts a fractional slot concentrated winding form. By adjusting the matching relationship between the number of stator slots 13 and permanent magnets 22, a high fundamental winding factor is obtained, and specific harmonics are suppressed from the winding magnetomotive force level. Slot pole matching optimization design based on fractional slot concentrated winding: The present invention preferably employs fractional slot concentrated winding technology, and carefully selects and optimizes the slot-to-pole ratio to achieve the best balance between electromagnetic performance and structural process. Selection of specific slot-pole ratio: Select slot-pole combination with high winding factor and effective suppression of main tooth harmonics, such as 12 slots with 10 poles, 24 slots with 22 poles, or 18 slots with 16 poles. The tooth harmonic number of fractional slot concentrated sets is higher, and the number of tooth cogging torque cycles generated is also more, but the amplitude is significantly lower than that of integer slot motors, and it is easy to further weaken it through other means (such as magnetic pole optimization). Advantages of the winding structure: The windings of the FSCW are directly wound on a single stator tooth 12, with extremely short ends, which greatly shortens the axial length of the motor and significantly improves the power density and torque density. At the same time, the reduction of copper loss at the ends directly improves the motor efficiency. In addition, the windings of each phase are highly decoupled physically and magnetically, with excellent fault tolerance. A failure in one phase will not immediately affect other phases, thus improving the reliability of the system.

[0026] Step 3: Magnetic circuit and structural design: Suppress magnetic circuit saturation by adjusting the geometry of stator teeth 12 and yoke 15; Integrated design of magnetic circuit saturation suppression and high-strength structure: This invention optimizes the dimensions and materials of key components of the magnetic circuit to ensure smooth magnetic circuit operation while also maintaining mechanical strength at high speeds. Stator magnetic circuit optimization: The geometric dimensions of stator teeth 12 and yoke 15 are parametrically optimized. Through finite element simulation analysis, the magnetic flux density distribution is accurately calculated, and the ratio of tooth width to yoke thickness (such as tooth-yoke ratio) is reasonably allocated to avoid sharp corners and narrow cross sections. This ensures that under peak torque conditions, the magnetic flux density of each part of the stator core 11 is uniform and all are in the linear region or slightly saturated region of the magnetization curve. This effectively controls iron loss and suppresses harmonics caused by saturation while ensuring high torque output. Rotor structure and material optimization: In view of the characteristics of ultra-high speed of flywheel, the rotor structure design combines electromagnetic performance with mechanical stress constraints; For surface-mount structures, high-strength, low-conductivity protective sleeves, such as carbon fiber, glass fiber, or high-strength alloys (such as titanium alloys), are used to pre-stress-wound or interference-fit the permanent magnet 22. The carbon fiber sleeve is not only high-strength and low-density, but also a non-magnetic and non-conductive material, which can effectively eliminate eddy current losses on the rotor surface. This is the key to improving the efficiency of ultra-high-speed motors. For the built-in structure, a magnetic bridge is provided in the rotor core 21 to fix the permanent magnet 22. By optimizing the shape and thickness of the magnetic bridge, while ensuring sufficient magnetic circuit isolation and reducing magnetic leakage, the structural integrity of the rotor core 21 under huge centrifugal force is ensured, and stress concentration is avoided. Auxiliary harmonic suppression structure: Based on the above optimization, auxiliary structures can be introduced to further finely control the magnetic field; for example, tiny auxiliary slots can be opened on the top of the stator tooth 12 or suppression slots can be cut on the surface of the permanent magnet 22. The size, position and shape of these microstructures are carefully designed to specifically weaken certain stubborn harmonics that are difficult to eliminate, so as to achieve "fine carving" of tooth cogging torque and torque pulsation.

[0027] Example 3: The process is basically the same as in Example 2, and the specific steps are as follows: High torque density flywheel motors for industrial UPS applications: This embodiment aims to design a flywheel motor for an industrial uninterruptible power supply (UPS) system. Its core requirement is to have extremely high instantaneous power response capability, i.e., high torque density. Basic parameters: Rated power 50kW, rated speed 20000rpm, peak speed 30000rpm; Slot-pole combination scheme: The fractional slot concentrated winding scheme with twelve slots and ten poles is adopted. This scheme has a high winding factor and can generate a large fundamental magnetomotive force. At the same time, its main tooth harmonic order is the least common multiple LCM(12,10) / p=60 / 5=12th, which is high and easy to be weakened. Air gap magnetic field optimization: Air gap structure: A uniform air gap is adopted to simplify the manufacturing process and reduce costs; the air gap length is set to 1.0 mm; Permanent magnet 22 design: An embedded V-shaped permanent magnet 22 array is adopted. Each pole consists of two rectangular sintered NdFeB (N52SH grade) permanent magnets 22 embedded in the rotor core 21 in a V-shape. The included angle of the V-shape is designed to be 140 degrees. This structure can utilize the magnetic field focusing effect to significantly increase the amplitude of the fundamental magnetic flux density in the air gap, thereby greatly increasing the torque without increasing the volume of the permanent magnet 22. At the same time, the V-shaped structure forms a magnetic flux barrier inside the rotor, increases the q-axis inductance, generates considerable reluctance torque, and further increases the total output torque. Magnetic circuit and structure optimization: Stator: The stator core 11 is made of high-grade silicon steel sheets (35W270) with a stack thickness of 100mm. The width of the stator teeth 12 and the thickness of the yoke are optimized through finite element analysis to control the magnetic flux density of the teeth at around 1.8T at peak torque and the magnetic flux density of the yoke 15 at around 1.6T, thus avoiding severe saturation. Rotor: The rotor core 21 is made of high-strength alloy steel (40CrNiMoA). The thickness of the magnetic bridge between the V-shaped slots is optimized to 1.5mm through stress simulation, ensuring that the maximum stress is far below the material yield limit at a speed of 30,000 rpm. The outer surface of the rotor core 21 is smooth, requiring no additional sheath, and the structure is robust. Performance testing: The motor of this embodiment was compared with a conventional motor using a traditional twelve-slot eight-pole surface tile-shaped permanent magnet 22 and distributed windings. The results are shown in the table below: Sample performance test table in Example 3 Example 4: The process is basically the same as in Example 2, and the specific steps are as follows: Ultra-low torque pulsating flywheel motors for powering precision instruments: The goal of this embodiment is to design a flywheel energy storage motor with extremely stable output for fields with extremely high power quality requirements, such as data centers and semiconductor manufacturing. The core requirement is to minimize torque ripple. Basic parameters: Rated power 20kW, rated speed 25000rpm, peak speed 35000rpm; Slot-pole matching scheme: The fractional slot concentrated winding scheme with 24 slots and 22 poles is adopted. The slot-pole ratio is close to 1, which has a very high harmonic suppression capability. The minimum number of cycles of its cogging torque is extremely large (LCM(24,22) / p=264 / 11=24), which makes the amplitude of the cogging torque naturally very small. Air gap magnetic field optimization: Air gap structure: A non-uniform air gap design is adopted. The air gap length g(θ) varies along the circumference according to the law g(θ) = gmin / cos(θe), where gmin is the minimum air gap at the pole center (0.8mm) and θe is the electrical angle. This makes the air gap magnetic permeability have an ideal cosine distribution. The permanent magnet 22 design adopts a surface-mounted, segmented magnet array with varying thicknesses. Each pole is composed of five tile-shaped neodymium iron boron magnets (N48UH grade) of different thicknesses spliced ​​together, with the central block being the thickest and gradually thinning towards both sides, forming a macroscopic shape resembling a "bread slice". This design makes the magnetomotive force waveform provided by the permanent magnet 22 highly sinusoidal. The synergistic effect of the non-uniform air gap and the segmented magnets makes the final synthesized air gap magnetic flux density waveform very close to a perfect sine wave, eliminating most harmonics at the source. Magnetic circuit and structure optimization: Stator: The stator core 11 uses ultra-thin silicon steel sheets with a thickness of 0.1mm to reduce iron loss at high frequencies. A pair of symmetrical auxiliary slots with a width of 0.5mm and a depth of 1mm are opened at the top of each stator tooth 12. The position and size of these auxiliary slots are optimized to counteract the most stubborn tooth harmonics caused by the slot effect, thereby achieving the "ultimate" suppression of tooth cogging torque. Rotor: The permanent magnet 22 is fixed by prestressed winding of a 1.2mm thick carbon fiber composite sheath. The carbon fiber sheath not only provides extremely high mechanical strength to meet the speed requirement of 35,000 rpm, but its non-conductive properties also completely eliminate eddy current losses on the rotor surface, which is crucial for improving high-speed efficiency. Performance testing: This embodiment was compared with a conventional FSCW motor using twelve slots, ten poles, uniform air gap, and integral tile magnets. The results are shown in the table below: Sample performance test table in Example 4 Example 5: The process is basically the same as in Example 2, and the specific steps are as follows: Ultra-high efficiency, high-speed flywheel motors for power grid frequency regulation applications: This embodiment is designed to meet the frequency regulation requirements of the power grid. Such applications require the flywheel system to be able to standby at a high speed for a long time and to respond quickly to the power dispatch of the power grid. Therefore, the core design objectives are ultra-high efficiency (especially standby efficiency) and high operating speed. Basic parameters: Rated power 200kW, rated speed 15000rpm, peak speed 40000rpm; Slot-pole combination scheme: The scheme adopts an eighteen-slot, sixteen-pole fractional-slot concentrated winding scheme, which also has good harmonic suppression characteristics and short-end advantages; Air gap magnetic field optimization: Air gap structure: A uniform air gap (1.5mm) is adopted to provide sufficient space for the high-strength sheath; Permanent magnet 22 design: The surface-mounted, "bread slice" shaped integral permanent magnet 22 is adopted. The side of the magnet (N50UH grade) facing the air gap is processed into a smooth convex arc surface, rather than a simple tile. This continuous curved surface is easier to achieve dynamic balance than the segmented splicing of Example 4, and can also effectively improve the air gap magnetic field waveform and weaken high-order harmonics. Magnetic circuit and structure optimization: Stator: The stator core 11 uses amorphous alloy material. Compared with silicon steel sheets, amorphous alloy has higher resistivity and extremely low coercivity, which can reduce iron loss (especially eddy current loss) at high frequencies by 70%-80%. This is the key to achieving ultra-high efficiency, especially reducing standby loss. Rotor: The rotor core 21 is made of a single piece of maraging steel, which has extremely high strength and toughness. The permanent magnet 22 is fixed by a high prestress interference fit through a 2.0mm thick high modulus carbon fiber sheath. The entire rotor structure has undergone precise dynamic balancing design, which can safely and stably operate at an ultra-high speed of 40,000 rpm. The rotor is designed with cooling air channels inside, which work together with the water cooling system of the stator housing to form an efficient heat dissipation circuit. Performance Testing: This embodiment was compared with a high-speed motor of the same specifications using high-grade silicon steel and a conventional surface-mount structure. The results are shown in the table below: Sample performance test table in Example 5 Components not described in detail in this article are existing technologies.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flywheel energy storage motor stator-rotor structure, comprising a stator body (1) and a rotor body (2), characterized in that: The stator body (1) includes a stator core (11), stator slots (13) are evenly provided on the stator core (11), stator teeth (12) are formed between two adjacent sets of stator slots (13), slot openings (16) are provided on the side of the stator slots (13) near the inner wall of the stator core (11), a shoe part (14) is formed on the side of the inner wall of the stator core (11) near the stator slots (13) and the slot openings (16), a yoke part (15) is formed between the stator slots (13) and the outer wall of the stator core (11), and a stator winding (17) is wound between two adjacent sets of stator slots (13). The rotor body (2) includes a rotor core (21), which is rotatably connected to the inside of the stator core (11). Multiple sets of permanent magnets (22) are inserted inside the rotor core (21). A protective structure (23) is inserted on the side of the rotor core (21) near the permanent magnets (22), and the protective structure (23) abuts against the permanent magnets (22). Also includes: The motor air gap (3) is formed between the inner wall of the stator core (11) and the outer wall of the rotor core (21).

2. The stator-rotor structure of a flywheel energy storage motor according to claim 1, characterized in that: The stator core (11) or rotor core (21) is made of silicon steel, alloy steel, amorphous alloy or maraging steel to reduce high-frequency loss.

3. The stator-rotor structure of a flywheel energy storage motor according to claim 1, characterized in that: The protective structure (23) is made of glass fiber composite material, non-magnetic alloy material, carbon fiber or carbon fiber composite material to withstand high-speed centrifugal force. When the motor is a surface-mounted permanent magnet motor, the protective structure (23) is a sheath made of carbon fiber composite material, glass fiber composite material or non-magnetic alloy material.

4. A method for optimizing the stator-rotor structure of a flywheel energy storage motor, employing the stator-rotor structure of a flywheel energy storage motor as described in any one of claims 1-3, wherein the motor structure is formed by at least two of the following designs, characterized in that, Includes the following steps: Step 1: Air gap magnetic field design: By adjusting the shape and arrangement of the motor air gap (3) or permanent magnet (22), the magnetic flux density waveform of the motor air gap (3) when unloaded is close to a sine wave to suppress harmonics; Step 2: Slot-pole matching design: The stator winding (17) adopts a fractional slot concentrated winding form. By adjusting the matching relationship between the stator slot (13) and the number of permanent magnet poles (22), a high fundamental winding factor is obtained, and specific subharmonics are suppressed from the winding magnetomotive force level. Step 3: Magnetic circuit and structural design: Magnetic circuit saturation is suppressed by adjusting the geometry of the stator teeth (12) and yoke (15).

5. The method for optimizing the stator-rotor structure of a flywheel energy storage motor according to claim 4, characterized in that, In step one, the motor air gap (3) is designed as a non-uniform air gap. The length of the air gap is a preset value in the direction of the center line of each pole, and increases smoothly in the direction of the magnetic pole edge in the circumferential direction according to a preset function. The preset function is a parabolic function or a cosine function.

6. The method for optimizing the stator-rotor structure of a flywheel energy storage motor according to claim 4, characterized in that, In step one, the permanent magnet (22) is shaped like a "bread slice" and the surface facing the motor air gap (3) is a raised arc surface.

7. The method for optimizing the stator-rotor structure of a flywheel energy storage motor according to claim 4, characterized in that, In step one, the permanent magnets (22) are arranged in a segmented combination, in a V-shape, W-shape or Halbach array.

8. The method for optimizing the stator-rotor structure of a flywheel energy storage motor according to claim 4, characterized in that, In step two, the combination of the number of stator slots (13) and the number of permanent magnet poles (22) includes twelve slots with ten poles, twenty-four slots with twenty-two poles, or eighteen slots with sixteen poles.

9. The method for optimizing the stator-rotor structure of a flywheel energy storage motor according to claim 4, characterized in that, In step three, when the motor is a built-in permanent magnet motor, a magnetic bridge for fixing the permanent magnet (22) is provided in the rotor core (21). The shape and thickness of the magnetic bridge are adjusted to ensure magnetic circuit isolation while meeting the mechanical strength requirements under high-speed operation.

10. The method for optimizing the stator-rotor structure of a flywheel energy storage motor according to claim 4, characterized in that, In step three, an auxiliary harmonic suppression structure is included, which is an auxiliary groove opened on the top of the stator tooth (12) or a suppression groove opened on the surface of the permanent magnet (22).

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