Permanent magnetization energy-saving reconstruction structure and method of original asynchronous motor

Abstract

The application discloses a permanent magnetization energy-saving reconstruction structure and method of an original asynchronous motor, and belongs to the technical field of motor energy-saving reconstruction. The outer circumferential surface of a rotor core of the original asynchronous motor is processed with a stepped skew pole slot, and a surface-mounted bottom flat arc magnetic steel is embedded in the stepped skew pole slot; a non-magnetic protection sleeve is coated on the outer circumferential surface of the magnetic steel, and axial limiting structures are arranged at both ends of the rotor core. The application further discloses a reconstruction method of the structure, which comprises the following steps: disassembly and detection, rotor pretreatment, stepped skew pole slot processing, insulation treatment, magnetic steel installation and fixation, protection structure installation and dynamic balance assembly. The application adopts a multiple magnetic steel fixation mechanism, is high in operation reliability, can improve energy efficiency to above the IE4 standard, is low in reconstruction cost, is high in universality, and is suitable for large-scale reconstruction of low-energy-efficiency asynchronous motors with different powers and pole numbers.

Description

Technical Field

[0001] This invention relates to the field of motor energy-saving retrofit technology, specifically to a permanent magnetization energy-saving retrofit structure and method for an original asynchronous motor. Background Technology

[0002] Asynchronous motors are the most widely used power equipment in industrial production and people's lives, with a huge existing stock. However, a large number of in-service asynchronous motors have an energy efficiency rating below IE3, which means they are low-efficiency motors with high energy consumption and low operating efficiency, resulting in huge energy waste.

[0003] Currently, there are two main approaches to energy-saving retrofitting of inefficient asynchronous motors: one is to directly replace them with brand-new high-efficiency permanent magnet motors. Although this method significantly improves energy efficiency, a large number of old asynchronous motors are directly scrapped and recycled, which only achieves low-value recycling of metal materials. The utilization value of reusable components such as the iron core and stator is not fully utilized, resulting in resource waste. Moreover, the equipment purchase cost is high, placing a heavy economic burden on enterprises and making it difficult to promote on a large scale. The second approach is to use variable frequency speed control retrofitting. This method can only optimize the operating conditions of the motor and cannot improve its electromagnetic efficiency from the perspective of the motor's structure, resulting in limited energy-saving effects.

[0004] In addition, some existing technologies for retrofitting asynchronous motors with permanent magnets generally suffer from defects such as unreliable magnet fixing, easy detachment during high-speed operation, high harmonic losses leading to severe motor overheating, complex retrofitting processes, and poor versatility. Summary of the Invention

[0005] This invention provides a permanent magnetization energy-saving retrofit structure and method for existing asynchronous motors, solving the technical problems of high energy consumption, high replacement cost, low utilization rate of waste motor resources, poor stability and weak versatility of existing retrofit technologies for existing inefficient asynchronous motors.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A permanent magnetization energy-saving retrofit structure for an original asynchronous motor includes: The stepped inclined pole slots are evenly distributed at equal angles along the outer peripheral surface of the original asynchronous motor rotor core. The stepped inclined pole slots are arranged in a stepped inclined manner, and their depth and width are distributed in a stepped manner along the inclined pole direction. The surface-mounted flat-top arc-shaped magnets are fixedly embedded in the stepped oblique pole slots one by one. The bottom of the flat-top arc-shaped magnet is flat and fits the bottom of the stepped oblique pole slot. The top of the flat-top arc-shaped magnet is arc-shaped and together with the outer circumference of the original asynchronous motor rotor core, they form a smooth cylindrical surface.

[0007] As a further aspect of the present invention: the number of steps in the stepped skewed pole slot is 2-8, the difference in depth between adjacent stepped skewed pole slots is 0.5mm-2mm, the difference in width is 1mm-3mm, the skewed pole angle is 2°-8°, and the distribution direction of the steps is consistent with the rotation direction of the original asynchronous motor rotor.

[0008] As a further aspect of the present invention: the surface-mounted bottom-flat-top arc-shaped magnet is a neodymium iron boron magnet with a thickness of 3mm-10mm and a pole arc coefficient of 0.7-0.85; the surface-mounted bottom-flat-top arc-shaped magnet is arranged with alternating N and S poles along the circumference of the original asynchronous motor rotor core.

[0009] As a further aspect of the present invention, it also includes a magnet fixing structure, which includes structural adhesive coated between the inner wall of the stepped inclined pole groove and the corresponding surface-mounted bottom flat-top arc-shaped magnet, as well as a positioning protrusion disposed on the side wall of the stepped inclined pole groove and a positioning groove disposed on the side wall of the corresponding surface-mounted bottom flat-top arc-shaped magnet, wherein the positioning protrusion and the positioning groove engage with each other.

[0010] As a further aspect of the present invention, it also includes a protective structure, which includes a non-magnetic protective sleeve covering the outer periphery of all the surface-mounted bottom-flat-top arc-shaped magnets, and an axial limiting structure disposed at both ends of the original asynchronous motor rotor core.

[0011] As a further embodiment of the present invention: the non-magnetic protective sleeve is one of carbon fiber sleeve, stainless steel thin sleeve or glass fiber sleeve, with a wall thickness of 0.3-1.5mm, and the non-magnetic protective sleeve covers the outer periphery of all the surface-mount bottom flat top arc-shaped magnets by interference fit; The axial limiting structure is an annular baffle integrally machined with the original asynchronous motor rotor core, or a non-magnetic retaining ring disposed at both ends of the original asynchronous motor rotor core. The outer diameter of the annular baffle or the non-magnetic retaining ring is larger than the outer diameter of the non-magnetic protective sleeve.

[0012] This invention also provides a method for energy-saving retrofitting of an original asynchronous motor by permanent magnetization, characterized by the following steps: S1. Disassemble the original asynchronous motor, separating and retaining the stator, end cover and bearings; S2. Remove the guide bars and end rings of the original asynchronous motor rotor, and clean the surface of the original asynchronous motor rotor core. S3. Using CNC milling or grinding processes, a stepped skewed pole slot is formed on the outer circumferential surface of the original asynchronous motor rotor core. S4. Insulate the surface of the original asynchronous motor rotor core and the inner wall of the stepped skewed pole slot after processing. S5. Apply strong structural adhesive to the stepped inclined pole groove, and embed the surface-mounted bottom flat top arc-shaped magnet into the stepped inclined pole groove in the alternating N and S pole order, so that the positioning protrusion engages with the corresponding positioning groove, and apply pressure to cure. S6. The non-magnetic protective sleeve is wrapped around the outer periphery of the surface-mounted bottom-flat-top arc-shaped magnet by heat fitting process, and axial limiting structures are installed at both ends of the original asynchronous motor rotor core. S7. Perform dynamic balancing correction on the original asynchronous motor rotor after modification, and then assemble it with the components retained in step S1.

[0013] As a further aspect of the present invention: in step S3, the coaxiality error of the original asynchronous motor rotor core is controlled to not exceed 0.02mm during processing, and the dimensional tolerance of the stepped skewed pole slot is controlled within the range of ±0.05mm.

[0014] As a further aspect of the present invention, the insulation treatment step in step S4 is as follows: the surface of the original asynchronous motor rotor core and the inner wall of the stepped skewed pole slot are subjected to phosphating treatment or sprayed with an insulating coating with a thickness of 10-30μm.

[0015] As a further aspect of the present invention: in step S5, a pressure of 0.1-0.3 MPa is applied, and the mixture is cured at room temperature for 2-4 hours; In step S6, the non-magnetic protective sleeve is heated to 120-200℃ before being heat-fitted.

[0016] The beneficial effects of this invention are: By machining the rotor of the low-efficiency original asynchronous motor with stepped skewed pole slots and precisely matching it with surface-mounted bottom flat-top arc-shaped magnets, combined with standardized modification processes, the modified motor can achieve IE4 and above standards. Compared with the original asynchronous motor, the operating efficiency is improved by 8%-15%, and the no-load loss is reduced by more than 40%, effectively reducing the energy consumption of motor operation and helping enterprises achieve carbon emission reduction targets. By fully reusing the stator, frame and other usable parts of the original asynchronous motor, the high-value recycling of the waste asynchronous motor can be achieved, avoiding resource waste. At the same time, the transformation cost is only 40%-60% of the cost of purchasing a new permanent magnet motor, which greatly reduces the economic burden of enterprise equipment replacement. The four-fold fixing method of structural adhesive bonding, positioning protrusion engagement, non-magnetic protective sleeve covering and axial limiting ensures that the surface-mounted bottom flat top arc-shaped magnet is firmly installed, which can adapt to high-speed operation above 3000r / min, with no risk of magnet falling off. In addition, the stepped slanted pole structure effectively reduces harmonic loss and electromagnetic noise, and improves the smoothness of motor operation. The retrofit process is compatible with low-efficiency asynchronous motors of different power (0.75kW-315kW) and different number of poles (2 poles, 4 poles, 6 poles, 8 poles). The retrofit process is standardized, can achieve batch retrofitting, has a wide range of applications, and is easy to promote and apply on a large scale. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the overall structure of the permanent magnetization energy-saving retrofit structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the stepped inclined pole type slot structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the surface-mounted bottom-flat-top arc-shaped magnet installed in a stepped inclined pole slot according to an embodiment of the present invention; Figure 4 yes Figure 2 Enlarged schematic diagram of the structure at point A in the middle; Figure 5 This is a schematic diagram of the surface-mounted bottom-flat-top arc-shaped magnet structure according to an embodiment of the present invention; Figure 6 This is a schematic diagram of another perspective of the surface-mounted bottom-flat-top arc-shaped magnet structure according to an embodiment of the present invention.

[0019] In the diagram: 1. Tiered oblique pole slot; 2. Rotor core; 3. Surface-mounted bottom flat top arc magnet; 4. Positioning protrusion; 5. Positioning groove; 6. Non-magnetic protective sleeve; 7. Axial limiting structure. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking," etc., should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Traditional asynchronous motors are widely used in industrial production and daily life, but many in-service asynchronous motors have low energy efficiency ratings, resulting in high energy consumption and low operating efficiency, leading to significant energy waste. Current energy-saving retrofit solutions for inefficient asynchronous motors, such as directly replacing them with high-efficiency permanent magnet motors or using variable frequency speed control, are limited by high costs, resource waste, or limited energy-saving effects. Furthermore, existing asynchronous motor permanent magnet retrofit technologies generally suffer from drawbacks such as unreliable magnet fixing, easy detachment at high speeds, high harmonic losses leading to severe motor overheating, complex retrofit processes, and poor versatility.

[0024] For this, please refer to Figure 1-6 As shown, this embodiment of the invention provides a permanent magnetization energy-saving retrofit structure for an original asynchronous motor, which may include at least a stepped slanted pole type slot 1 and a surface-mounted bottom flat-top arc-shaped magnet 3.

[0025] Multiple stepped inclined pole slots 1 are evenly distributed at equal angles along the outer peripheral surface of the original asynchronous motor rotor core 2. The stepped inclined pole slots 1 are arranged in a stepped inclined manner, and their depth and width are distributed in a stepped manner along the inclined pole direction.

[0026] For example, when modifying the original asynchronous motor rotor core 2, these stepped, skewed pole slots 1 can be formed on the outer circumferential surface of the rotor core 2 through machining methods such as milling or grinding. (See also...) Figure 2 In this embodiment, the stepped inclined pole type 1 is designed as a stepped inclined pole type, that is, the depth and width of the groove change in a stepped manner along the inclined pole direction, and the groove itself has a certain inclination angle.

[0027] See Figure 3A surface-mounted, flat-bottomed, arc-shaped magnet 3 is fixedly embedded in the corresponding stepped, slanted-pole slot 1. The bottom of this surface-mounted, flat-bottomed, arc-shaped magnet 3 is flat and fits snugly against the bottom of the corresponding stepped, slanted-pole slot 1. The top of this surface-mounted, flat-bottomed, arc-shaped magnet 3 is arc-shaped and together with the outer circumferential surface of the original asynchronous motor rotor core 2, forms a smooth cylindrical surface. In this embodiment, the surface-mounted, flat-bottomed, arc-shaped magnet 3 is designed with a flat bottom and an arc-shaped top to ensure a tight fit with the stepped, slanted-pole slot 1 and a smooth transition with the outer circumferential surface of the original asynchronous motor rotor. This surface-mounted, flat-bottomed, arc-shaped magnet 3 can be made of high-performance permanent magnet material and precisely dimensionally machined to meet the embedding requirements.

[0028] This application achieves permanent magnetization retrofitting of low-efficiency asynchronous motors by machining stepped, skewed pole slots 1 on the rotor core 2 of the original asynchronous motor and embedding surface-mounted, flat-bottomed, arc-shaped magnets 3. This structural design helps optimize the rotor magnetic field distribution, reduce harmonic losses, and improve the operating efficiency of the asynchronous motor. Simultaneously, it avoids the scrapping of a large number of old motors, effectively utilizes existing resources, and provides an economical and efficient solution for energy-saving upgrades of in-service asynchronous motors.

[0029] In some specific implementations, see [reference] Figure 2The number of steps in the stepped skewed pole slot 1 is set to 2-8. The number of steps is crucial for simulating continuous skewed pole effects, directly impacting the motor's ability to suppress magnetic field harmonics. Too few steps result in an insignificant skewed pole effect, making it difficult to effectively reduce torque ripple; while too many steps, although achieving a closer skewed pole effect than continuous skewed pole effects, significantly increase manufacturing difficulty and cost. Therefore, limiting the number of steps to 2-8 ensures good skewed pole effects while considering manufacturing feasibility and economy. The depth difference between adjacent stepped skewed pole slots 1 is set to 0.5mm-2mm. This depth difference determines the radial distribution gradient of the magnets, thus affecting the radial distribution of the air gap magnetic field. A reasonable depth difference helps optimize the magnetic field waveform, reduce higher harmonic components, and thereby reduce eddy current losses and torque ripple. The width difference between adjacent stepped skewed pole slots 1 is set to 1mm-3mm. The slot width difference affects the circumferential distribution of the surface-mounted bottom-flat-top arc-shaped magnet 3, thus influencing the effective width of the magnetic poles and the magnetic flux path. By controlling the slot width difference, the shape of the magnetic poles can be finely adjusted to obtain a more ideal air gap magnetic field distribution, further suppressing harmonics and improving the smoothness of motor operation. The slant angle of the stepped skewed pole slot 1 is set to 2°-8°. The slant angle is an important parameter for suppressing cogging torque and torque pulsation. By creating a tilt angle between the magnetic pole axis and the rotor axis, the magnetic field can gradually change in the axial direction, thereby effectively weakening the influence of magnetic field harmonics on torque. The slant angle range of 2°-8° is an effective range proven in practice, significantly improving the operating quality of the motor. In addition, the distribution direction of the steps is consistent with the original asynchronous motor rotor rotation direction. This consistency ensures that the change of the magnetic field during motor rotation is coordinated with the rotor movement direction, helping to optimize the magnetic field distribution, reduce additional losses and vibrations caused by magnetic field inhomogeneity, and further improve the operating efficiency and stability of the motor.

[0030] In some specific embodiments, the surface-mounted bottom-flat-top arc-shaped magnet 3 preferably uses neodymium iron boron (NdFeB) magnets. NdFeB magnets, as a high-performance rare-earth permanent magnet material, are renowned for their high remanence, high coercivity, and high energy product. Applying them to permanent magnetization structures can provide a strong permanent magnet field, which is key to achieving efficient motor operation and significant energy savings. The excellent magnetic properties of this material ensure sufficient magnetic flux within a limited space, thereby improving the motor's power density and efficiency. Meanwhile, the thickness of the surface-mounted bottom-flat-top arc-shaped magnet 3 is limited to the range of 3mm to 10mm. Thickness is an important parameter affecting the air gap magnetic field strength, magnetic circuit saturation, and rotor mechanical strength. This range is chosen to balance the relationship between the magnetic flux provided by the surface-mounted bottom-flat-top arc-shaped magnet 3 and the rotor structural integrity, ensuring that the surface-mounted bottom-flat-top arc-shaped magnet 3 provides sufficient magnetic energy while maintaining the stability and reliability of the rotor structure. Furthermore, the pole arc coefficient of the surface-mounted bottom-flat-top arc-shaped magnet 3 is set to 0.7 to 0.85. The pole arc coefficient is defined as the ratio of the arc length to the pole pitch of the surface-mounted bottom-flat-top arc-shaped magnet 3. It is a key geometric parameter characterizing the coverage range of the surface-mounted bottom-flat-top arc-shaped magnet 3 in the rotor circumference. This coefficient directly affects the waveform, harmonic content, and torque pulsation of the motor's air gap magnetic field. Setting the pole arc coefficient within this range helps optimize the air gap magnetic field distribution, making it closer to the ideal sine waveform, thereby effectively reducing losses and torque pulsation caused by higher harmonics and improving the motor's running smoothness and efficiency. Furthermore, the surface-mounted bottom-flat-top arc-shaped magnet 3 is arranged with alternating N and S poles along the circumference of the original asynchronous motor rotor core 2. This alternating N and S pole arrangement is fundamental to the generation of a continuous rotating magnetic field in permanent magnet motors. By alternating the arrangement of surface-mounted bottom-flat-top arc-shaped magnets 3 of different polarities along the circumference of the original asynchronous motor rotor core 2, it is possible to ensure that the magnetic lines of force form a closed loop between the stator and rotor, and generate a periodically changing magnetic field as the rotor rotates. This magnetic field then interacts with the rotating magnetic field generated by the stator windings, producing a stable electromagnetic torque to drive the motor. This arrangement is a necessary condition for permanent magnet motors to realize their basic working principle and efficient energy conversion.

[0031] Further, please refer to Figures 4-6This application proposes a magnet fixing structure to ensure the stable installation of a surface-mounted, flat-topped, arc-shaped magnet 3 within a corresponding stepped, slanted-pole groove 1. The magnet fixing structure includes high-strength structural adhesive and positioning protrusions 4. The bottom and walls of the stepped, slanted-pole groove 1 are uniformly coated with high-strength structural adhesive. The surface-mounted, flat-topped, arc-shaped magnet 3 is firmly bonded to the corresponding stepped, slanted-pole groove 1 through this structural adhesive, with a bonding strength of not less than 15 MPa. The structural adhesive can be epoxy resin, polyurethane, or acrylic structural adhesive, etc., and its selection should comprehensively consider bonding strength, temperature resistance, and curing characteristics. Simultaneously, positioning protrusions 4 are provided on both side walls of the corresponding stepped, slanted-pole groove 1, and corresponding positioning grooves 5 are provided on both sides of the surface-mounted, flat-topped, arc-shaped magnet 3. The positioning protrusions 4 and positioning grooves 5 engage and cooperate, further restricting the circumferential displacement of the surface-mounted, flat-topped, arc-shaped magnet 3, preventing it from falling off during high-speed motor operation, and improving fixing reliability. This combined fixing method significantly improves the installation reliability and stability of the surface-mounted bottom-flat-top arc-shaped magnet 3 within the original asynchronous motor rotor core 2, effectively avoiding the risk of loosening, displacement, or detachment of the surface-mounted bottom-flat-top arc-shaped magnet 3 under complex operating conditions such as high-speed motor rotation, vibration, and thermal expansion and contraction. This not only ensures the long-term stable operation and safety performance of the modified motor but also ensures the precise position of the magnet, thereby maintaining a uniform distribution of the motor's magnetic field and contributing to achieving the expected energy-saving effect and high efficiency performance.

[0032] Further, see Figure 1 This application also proposes a protective structure, which specifically includes a non-magnetic protective sleeve 6 covering the outer periphery of all surface-mounted bottom-flat-top arc-shaped magnets 3, and axial limiting structures 7 disposed at both ends of the original asynchronous motor rotor core 2. The non-magnetic protective sleeve 6 is used to tightly cover the outer periphery of all surface-mounted bottom-flat-top arc-shaped magnets 3. Its non-magnetic characteristics are crucial, as they can prevent the formation of magnetic short-circuit paths outside the surface-mounted bottom-flat-top arc-shaped magnets 3, thereby not interfering with the magnetic field generated by the surface-mounted bottom-flat-top arc-shaped magnets 3 and ensuring the normal operating efficiency of the motor magnetic circuit.

[0033] Axial limiting structure 7 is installed at both ends of the original asynchronous motor rotor core 2. Its function is to limit the axial movement of the non-magnetic protective sleeve 6 and its internal surface-mounted bottom-flat-top arc-shaped magnet 3. During motor operation, due to factors such as temperature changes, vibration, or assembly tolerances, the rotor components may experience slight axial displacement. The axial limiting structure 7 provides a physical barrier to ensure that the surface-mounted bottom-flat-top arc-shaped magnet 3 and the non-magnetic protective sleeve 6 are fixed in the axial direction, preventing them from moving axially, thereby maintaining the overall dynamic balance and running accuracy of the rotor. This structure can be designed to be integrally formed with the rotor core 2, or installed at both ends of the rotor in the form of independent annular parts, retaining rings, etc.

[0034] In some specific embodiments, the non-magnetic protective sleeve 6 is one of carbon fiber sleeve, stainless steel thin sleeve or glass fiber sleeve, with a wall thickness of 0.3-1.5mm. The non-magnetic protective sleeve 6 is wrapped around the outer periphery of all surface-mounted bottom flat top arc-shaped magnets 3 by interference fit. The axial limiting structure 7 is an annular baffle integrally machined with the original asynchronous motor rotor core 2, or a non-magnetic retaining ring set at both ends of the original asynchronous motor rotor core 2. The outer diameter of the annular baffle or the non-magnetic retaining ring is larger than the outer diameter of the non-magnetic protective sleeve 6.

[0035] This application also proposes a method for energy-saving retrofitting of an original asynchronous motor by converting it to a permanent magnet.

[0036] The main steps are as follows: 1. Dismantling and testing of used asynchronous motors: Dismantle the original low-efficiency asynchronous motors and separate the stator, rotor, end covers and bearings; test the insulation performance of the stator windings. If the winding insulation is unqualified, repair it by impregnation. Keep the stator with qualified insulation for backup, without replacing the stator with a new one, thus reducing the cost of modification.

[0037] 2. Pretreatment of rotor core 2: The guide bars and end rings of the original asynchronous motor rotor are completely removed by heating, milling or chemical etching; the rotor core 2 of the original asynchronous motor is sandblasted to remove rust and slag, and the impurities, oxide layer and residual stains on the surface of the rotor core 2 are removed to ensure that the surface of the rotor core 2 is flat and clean, laying the foundation for subsequent processing.

[0038] 3. Machining of stepped skewed pole slot 1: CNC milling or grinding is used to machine stepped skewed pole slot 1 on the outer circumferential surface of rotor core 2. During the machining process, the number of steps, the angle of the skewed pole, the depth of the slot, and the difference in the width of the slot steps are strictly controlled to ensure machining accuracy. Among them, the coaxiality error of rotor core 2 shall not exceed 0.02mm, and the dimensional tolerance of the slot shall be controlled within ±0.05mm.

[0039] 4. Core insulation treatment: The surface of the processed rotor core 2 and the inner wall of the stepped skewed pole slot 1 are phosphated or sprayed with an insulating coating. The thickness of the insulating coating is controlled at 10-30μm to enhance the insulation performance of the rotor core 2, reduce eddy current losses during motor operation, and further improve motor energy efficiency.

[0040] 5. Magnet Installation and Fixing: Apply epoxy-based high-strength structural adhesive evenly to the stepped inclined pole groove 1. Precisely embed the surface-mount flat-top arc-shaped magnet 3 into the corresponding stepped inclined pole groove 1 in alternating N and S pole order, ensuring that the bottom of the surface-mount flat-top arc-shaped magnet 3 is tightly fitted to the bottom of the corresponding stepped inclined pole groove 1, and that the positioning protrusion 4 and the positioning groove 5 are precisely engaged. Apply a pressure of 0.1-0.3 MPa to fully bond the surface-mount flat-top arc-shaped magnet 3 to the corresponding stepped inclined pole groove 1. Cure at room temperature for 2-4 hours to ensure a firm bond and prevent the surface-mount flat-top arc-shaped magnet 3 from loosening.

[0041] 6. Installation of protective structure: Heat the non-magnetic protective sleeve 6 to 120-200℃, and use a heat-shrinking process to cover the outer periphery of all surface-mounted bottom flat-top arc-shaped magnets 3 with an interference fit. After natural cooling, it is firmly fixed. Install axial limiting structures 7 (annular baffles or non-magnetic baffles) at both ends of the rotor core 2 to complete the entire modification of the rotor.

[0042] 7. Dynamic balancing and motor assembly: Perform dynamic balancing tests on the modified rotor and use the weight removal method to ensure that the rotor balance accuracy reaches G2.5 level or above; assemble the corrected rotor with the spare stator, the repaired end cover and the new bearing to form a high-efficiency permanent magnet synchronous motor, thus completing the entire modification process.

[0043] The aforementioned modified structure optimizes the magnetic field distribution and reduces harmonic losses through the stepped, slanted pole slot 1; maintains uniform air gap and reduces wind resistance through the surface-mounted, flat-bottomed, arc-shaped magnet 3; reliably fixes the surface-mounted, flat-bottomed, arc-shaped magnet 3 through a combination of structural adhesive and positioning protrusions 4 / positioning grooves 5; and provides comprehensive mechanical protection through the non-magnetic protective sleeve 6 and axial limiting structure 7. Together, these solutions address the problems of low energy efficiency, unreliable magnet fixing, easy detachment during high-speed operation, and severe motor overheating due to high harmonic losses in the original asynchronous motor. This achieves energy-saving retrofitting of existing inefficient asynchronous motors and fully utilizes reusable components such as the original asynchronous motor rotor core 2, reducing the overall retrofit cost and demonstrating significant economic and environmental benefits.

[0044] The preferred embodiments of the present invention have been described in detail above and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A permanent magnetization energy-saving retrofit structure for an original asynchronous motor, characterized in that, include: The stepped inclined pole slots are evenly distributed at equal angles along the outer peripheral surface of the rotor core of the original asynchronous motor. The stepped inclined pole slots are arranged in a stepped inclined manner, and their depth and width are distributed in a stepped manner along the inclined pole direction. The surface-mounted flat-top arc-shaped magnets are fixedly embedded in the stepped oblique pole slots one by one. The bottom of the flat-top arc-shaped magnet is flat and fits the bottom of the stepped oblique pole slot. The top of the flat-top arc-shaped magnet is arc-shaped and together with the outer circumference of the original asynchronous motor rotor core, they form a smooth cylindrical surface.

2. The permanent magnetization energy-saving retrofit structure for an original asynchronous motor according to claim 1, characterized in that, The number of steps in the stepped skewed pole slot is 2-8. The difference in depth between adjacent stepped skewed pole slots is 0.5mm-2mm, the difference in width is 1mm-3mm, and the skewed pole angle is 2°-8°. The distribution direction of the steps is consistent with the rotor rotation direction of the original asynchronous motor.

3. The permanent magnetization energy-saving retrofit structure for an original asynchronous motor according to claim 1, characterized in that, The surface-mounted flat-top arc-shaped magnet is a neodymium iron boron magnet with a thickness of 3mm-10mm and a pole arc coefficient of 0.7-0.

85. The surface-mounted flat-top arc-shaped magnet is arranged with alternating N and S poles along the circumference of the original asynchronous motor rotor core.

4. The permanent magnetization energy-saving retrofit structure for an original asynchronous motor according to claim 1, characterized in that, It also includes a magnet fixing structure, which includes structural adhesive coated between the inner wall of the stepped inclined pole groove and the corresponding surface-mounted bottom flat-top arc-shaped magnet, as well as a positioning protrusion disposed on the side wall of the stepped inclined pole groove and a positioning groove disposed on the side wall of the corresponding surface-mounted bottom flat-top arc-shaped magnet, wherein the positioning protrusion and the positioning groove engage with each other.

5. The permanent magnetization energy-saving retrofit structure for an original asynchronous motor according to claim 1, characterized in that, It also includes a protective structure, which includes a non-magnetic protective sleeve covering the outer periphery of all the surface-mounted bottom-flat-top arc-shaped magnets, and an axial limiting structure set at both ends of the original asynchronous motor rotor core.

6. The permanent magnetization energy-saving retrofit structure for an original asynchronous motor according to claim 5, characterized in that, The non-magnetic protective sleeve is one of carbon fiber sleeve, stainless steel thin sleeve or glass fiber sleeve, the wall thickness of the non-magnetic protective sleeve is 0.3-1.5mm, and the non-magnetic protective sleeve covers the outer periphery of all the surface-mount bottom flat top arc-shaped magnets by interference fit; The axial limiting structure is an annular baffle integrally machined with the original asynchronous motor rotor core, or a non-magnetic retaining ring disposed at both ends of the original asynchronous motor rotor core. The outer diameter of the annular baffle or the non-magnetic retaining ring is larger than the outer diameter of the non-magnetic protective sleeve.

7. A method for energy-saving retrofitting of an original asynchronous motor by converting it to a permanent magnet, characterized in that, Includes the following steps: S1. Disassemble the original asynchronous motor, separating and retaining the stator, end cover and bearings; S2. Remove the guide bars and end rings from the original asynchronous motor rotor, and clean the surface of the original asynchronous motor rotor core. S3. Using CNC milling or grinding processes, a stepped skewed pole slot is formed on the outer circumferential surface of the original asynchronous motor rotor core. S4. Insulate the surface of the original asynchronous motor rotor core and the inner wall of the stepped skewed pole slot after processing. S5. Apply strong structural adhesive to the stepped inclined pole groove, and embed the surface-mounted bottom flat top arc-shaped magnet into the stepped inclined pole groove in the alternating N and S pole order, so that the positioning protrusion engages with the corresponding positioning groove, and apply pressure to cure. S6. The non-magnetic protective sleeve is wrapped around the outer periphery of the surface-mounted bottom-flat-top arc-shaped magnet by heat fitting process, and axial limiting structures are installed at both ends of the original asynchronous motor rotor core. S7. Perform dynamic balancing correction on the original asynchronous motor rotor after modification, and then assemble it with the components retained in step S1.

8. The method for permanent magnetizing and energy-saving retrofitting of an original asynchronous motor according to claim 7, characterized in that, In step S3, during processing, the coaxiality error of the original asynchronous motor rotor core is controlled to not exceed 0.02mm, and the dimensional tolerance of the stepped skewed pole slot is controlled within ±0.05mm.

9. A method for permanent magnetizing and energy-saving retrofitting of an original asynchronous motor according to claim 7, characterized in that, The insulation treatment step in step S4 is as follows: phosphating or spraying an insulating coating with a thickness of 10-30μm is performed on the surface of the original asynchronous motor rotor core and the inner wall of the stepped skewed pole slot.

10. A method for permanent magnetizing and energy-saving retrofitting of an original asynchronous motor according to claim 7, characterized in that, In step S5, a pressure of 0.1-0.3 MPa is applied, and the material is cured at room temperature for 2-4 hours. In step S6, the non-magnetic protective sleeve is heated to 120-200℃ and then heat-fitted.

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