Rotor topological structure for preventing demagnetization of magnetic steel

Abstract

The invention discloses a rotor topological structure for preventing demagnetization of magnetic steel, which comprises a rotor iron core, the rotor iron core is provided with a plurality of magnetic poles, main magnetic steel grooves which are symmetrically arranged in a V shape are arranged on the rotor iron core under the same magnetic pole, and main magnetic steel made of neodymium iron boron materials is embedded in the main magnetic steel grooves. Auxiliary magnetic steel grooves are respectively arranged near two end parts of the main magnetic steel close to the excircle direction of the rotor, auxiliary magnetic steel made of samarium cobalt materials is embedded in the auxiliary magnetic steel grooves, and the auxiliary magnetic steel is used for increasing the local magnetic resistance of the area where the auxiliary magnetic steel is located so as to restrain the demagnetization of the end parts of the main magnetic steel; the design cost of the rotor topological structure is slightly increased, the influence on a main magnetic field is small, and the anti-demagnetization capability can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor manufacturing, more particularly to a rotor topology structure for preventing demagnetization of magnetic steel. BACKGROUND

[0002] At present, the market penetration rate of new energy vehicles at home and abroad is increasing year by year, and the performance of the driving motor as the core component of the new energy vehicle directly affects the efficiency and reliability of the vehicle.

[0003] The new energy vehicle driving motor generally adopts a permanent magnet synchronous motor, which mainly consists of a winding type stator and a rotor with embedded magnetic steel. The magnetized magnetic steel provides the main excitation magnetic field for the motor. Neodymium iron boron material has the highest magnetic energy product, and in order to improve the power density of the motor, it has become the most commonly used permanent magnet material. However, under complex working conditions, such as high temperature environment or reverse magnetic field, the magnetic steel is prone to irreversible demagnetization, which leads to a decrease in motor performance or even failure. This problem is particularly prominent in high power density motor design, which seriously restricts the reliability and durability of the new energy vehicle driving system. Therefore, how to effectively improve the anti-demagnetization capability of the magnetic steel has become one of the key technical problems in current motor design.

[0004] In order to solve the above problems, the existing technology mainly improves the anti-demagnetization performance by increasing the thickness of the magnetic steel, increasing the gap between the core slot and the magnetic steel, and increasing the auxiliary slot. However, these methods still have certain limitations in practical application. For example, increasing the thickness will increase the cost of the motor, and increasing the gap between the core slot and the magnetic steel and increasing the auxiliary slot may cause uneven magnetic field distribution and increase the obstruction of the core magnetic circuit, affecting the torque and power performance of the motor. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a rotor topology structure with little cost increase, small impact on the main magnetic field, and significant improvement in anti-demagnetization capability to solve the above technical problems.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A rotor topology structure for preventing demagnetization of magnetic steel, comprising a rotor core, the rotor core having a plurality of magnetic poles, a main magnetic steel slot arranged symmetrically in a V shape under the same magnetic pole is provided on the rotor core, a main magnetic steel of neodymium iron boron material is embedded in the main magnetic steel slot, an auxiliary magnetic steel slot is provided near each end of the main magnetic steel close to the outer circle direction of the rotor, a auxiliary magnetic steel of samarium cobalt material is embedded in the auxiliary magnetic steel slot, and the auxiliary magnetic steel is used to increase the local magnetic resistance of the region to suppress the demagnetization of the end of the main magnetic steel.

[0007] Further, the main magnetic steel and the auxiliary magnetic steel are both rectangular, and the magnetization direction of the auxiliary magnetic steel is the same as that of the main magnetic steel.

[0008] Further, the length gap distance between the auxiliary magnetic steel and the auxiliary magnetic steel slot is L / 200, and the width gap distance is W / 50, wherein L is the length value of the auxiliary magnetic steel, and W is the width value of the auxiliary magnetic steel.

[0009] Further, among the two auxiliary magnetic steels, the auxiliary magnetic steel close to one side of the rotor outer circle is the first auxiliary magnetic steel, and the other is the second auxiliary magnetic steel, the included angle A2 between the first auxiliary magnetic steel and the main magnetic steel satisfies: -5° ≤ A2 ≤ 5°, and the included angle A3 between the second auxiliary magnetic steel and the main magnetic steel satisfies: -4° ≤ A3 ≤ 6°.

[0010] Further, the shape aspect ratio X1 = L2:W2 of the first auxiliary magnetic steel satisfies: 1.5 ≤ X1 ≤ 5, wherein L2 is the length value of the first auxiliary magnetic steel, and W2 is the width value of the first auxiliary magnetic steel; and the shape aspect ratio X2 = L3:W3 of the second auxiliary magnetic steel satisfies: 2.5 ≤ X2 ≤ 5, wherein L3 is the length value of the second auxiliary magnetic steel, and W3 is the width value of the second auxiliary magnetic steel.

[0011] Further, the widths W1, W2 and W3 of the main magnetic steel and the auxiliary magnetic steel are all not less than 2mm, and the length ratio X3 = L1:L2 or L1:L3 of the main magnetic steel and the auxiliary magnetic steel satisfies: 8 ≤ X3 ≤ 12.

[0012] Further, the distance D between the angle close to the rotor center of the auxiliary magnetic steel and the main magnetic steel satisfies: (n / 3000)² × L / 5 + 1mm ≤ D ≤ (n / 3000)² × L / 5 + 2mm, wherein the peak speed of the motor is n, the unit is rpm, and L is the length value of the auxiliary magnetic steel.

[0013] Further, the minimum distance between the main magnetic steel slot and the rotor outer circle is D2, and the minimum distance between the auxiliary magnetic steel slot and the rotor outer circle is D3, and the ratio X4 = D2:D3 satisfies: 0.95 ≤ X4 ≤ 1.1.

[0014] Further, the total volume of the auxiliary magnetic steel accounts for 3% to 5% of the total volume of the main magnetic steel.

[0015] Compared with the prior art, the beneficial effects of the present application are: 1. High efficiency anti-demagnetization, significantly improved reliability: The core of the application is to cleverly set high coercivity, high thermal stability SmCo auxiliary magnetic steel in the sharp corner area of the main magnetic steel at both ends of the traditional V-shaped permanent magnet rotor, which is most prone to demagnetization. The permeability of SmCo material is close to air, which can form a high magnetic resistance "barrier" in this area; when the motor is in harsh conditions such as high temperature and overload, the strong reverse demagnetizing magnetic field generated by the stator will preferentially pass through the path with lower magnetic resistance, thereby being hindered and shunted by this layer of "barrier", significantly reducing the demagnetizing magnetic field strength acting on the dangerous area of the neodymium iron boron main magnetic steel, and fundamentally inhibiting the occurrence of irreversible demagnetization. The use of this structure can increase the rotor's anti-demagnetization ability by more than 13%.

[0016] 2. Main performance is maintained with minimal impact: The application does not simply increase the amount of magnetic steel, but through precise electromagnetic design and parameter optimization, the introduction of auxiliary magnetic steel minimizes its impact on the main performance indicators of the motor (such as output torque, power density, and no-load back EMF) and magnetic field distribution (such as torque ripple and magnetic field sinusoidal degree). The size, position, and angle of the auxiliary magnetic steel are optimized to ensure that it plays a magnetic protection role while not sacrificing the core power performance of the motor.

[0017] 3. Excellent cost control, high cost performance: Although the unit price of SmCo material is higher than that of NdFeB, its usage in the application is very small, accounting for only 3% to 5% of the total volume of the main magnetic steel, resulting in minimal increase in overall material cost while achieving significant performance improvement, with high commercial value.

[0018] 4. Good process, easy to implement: The size design of the auxiliary magnetic steel slot (such as gap L / 200, W / 50) in the application fully considers the strength of the punching die in mass production and the magnetic steel embedding process, ensuring that the magnetic steel can be installed smoothly and avoiding excessive gap that leads to invalid increase in magnetic resistance, balancing manufacturing feasibility and electromagnetic efficiency.

[0019] 5. Optimized comprehensive performance, strong robustness: By setting specific angles, aspect ratios, distance ratios, and slot depth ratios between the auxiliary magnetic steel and the main magnetic steel, the application achieves the best balance between suppressing demagnetization, maintaining magnetic field waveform, ensuring mechanical strength, and reducing magnetic leakage, making the motor's comprehensive operating robustness (reliability) in extreme conditions such as high speed and high temperature significantly enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 A schematic diagram of a rotor topology for preventing demagnetization of magnets; Figure 2 A partial schematic diagram of a rotor topology for preventing demagnetization of magnets; Figure 3 for Figure 2 Enlarged view of point I in the middle; Figure 4 for Figure 2 Enlarged view at point II; Figure 5 This is a comparison chart of the output torque and demagnetizing performance of the present invention with other existing structural designs.

[0021] The markings in the diagram are: 1. Rotor core; 2. First auxiliary magnet; 3. Main magnet; 4. Second auxiliary magnet; 5. Main magnet slot; 6. Auxiliary magnet slot. Detailed Implementation

[0022] In the description of this invention, it should be noted that the directional terms such as "center", "horizontal (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and 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 be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature. In the description of this invention, "several" or "a number" means two or more, unless otherwise explicitly specified.

[0024] A rotor topology to prevent demagnetization of the magnets, such as Figures 1-4As shown, including rotor core 1, the rotor core 1 has a plurality of magnetic poles, under the same magnetic pole, the rotor core 1 is provided with a main magnetic steel slot 5 arranged in V type symmetry, the main magnetic steel slot 5 is embedded with a main magnetic steel 3 of neodymium iron boron material, near the two ends of the main magnetic steel 3 close to the rotor outer circle direction, each is provided with an auxiliary magnetic steel slot 6, the auxiliary magnetic steel slot 6 is embedded with an auxiliary magnetic steel of samarium cobalt material, the auxiliary magnetic steel is used to increase the local magnetic resistance of the area where it is located, so as to inhibit the demagnetization of the end of the main magnetic steel 3.

[0025] Preferably, the main magnetic steel 3 and the auxiliary magnetic steel are rectangular, and the magnetization direction of the auxiliary magnetic steel is the same as that of the main magnetic steel 3. Specifically, the rectangular magnetic steel is convenient for processing and magnetization, and the magnetization direction of the auxiliary magnetic steel is consistent with that of the main magnetic steel 3, so that the magnetic fields generated by them are superimposed and beneficial in the main working area, rather than being cancelled out, thereby providing magnetic resistance protection while cooperating to contribute to the main excitation magnetic field and reducing the negative impact on the output capacity of the motor.

[0026] Preferably, the length gap distance between the auxiliary magnetic steel and the auxiliary magnetic steel slot 6 is L / 200, and the width gap distance is W / 50, wherein L is the length value of the auxiliary magnetic steel, and W is the width value of the auxiliary magnetic steel. Specifically, this gap design is a key process and electromagnetic balance point. If the gap is too small, the magnetic steel will be difficult to embed, and even damaged. If the gap is too large, a large "second air gap" will be formed in the magnetic circuit, resulting in excessive local magnetic resistance and unnecessary increase in magnetic pressure drop, thereby reducing the efficiency of the motor. The ratio of L / 200 and W / 50 of the present application can minimize the damage to the efficiency of the magnetic circuit on the premise of ensuring the feasibility of production. This design ensures the embeddability of the magnetic steel while avoiding excessive increase in magnetic resistance and reduction in efficiency due to the excessive gap between the auxiliary magnetic steel and the auxiliary magnetic steel slot 6 (i.e. the second air gap).

[0027] Preferably, among the two auxiliary magnetic steels, the auxiliary magnetic steel close to the outer circle of the rotor is the first auxiliary magnetic steel 2, and the other is the second auxiliary magnetic steel 4. The included angle A2 between the first auxiliary magnetic steel 2 and the main magnetic steel 3 satisfies: -5°≤ A2 ≤ 5°, and the included angle A3 between the second auxiliary magnetic steel 4 and the main magnetic steel 3 satisfies: -4° ≤ A3 ≤ 6°. Specifically, the installation angle of the auxiliary magnetic steel directly affects the distribution of the air gap magnetic field. By limiting the included angle within this small range, it can be ensured that the magnetic field of the auxiliary magnetic steel and the magnetic field of the main magnetic steel 3 can be smoothly integrated, effectively inhibiting the magnetic field distortion caused by structural mutation, thereby maintaining the sinusoidal nature of the air gap magnetic field, reducing torque ripple and electromagnetic noise.

[0028] Preferably, the shape aspect ratio X1 = L2:W2 of the first auxiliary magnetic steel 2 satisfies: 1.5 ≤ X1 ≤ 5, wherein L2 is the length value of the first auxiliary magnetic steel 2, and W2 is the width value of the first auxiliary magnetic steel 2; the shape aspect ratio X2 = L3:W3 of the second auxiliary magnetic steel 4 satisfies: 2.5 ≤ X2 ≤ 5, wherein L3 is the length value of the second auxiliary magnetic steel 4, and W3 is the width value of the second auxiliary magnetic steel 4. Specifically, the aspect ratio directly determines the "shape factor" of the auxiliary magnetic steel. Within the optimization range, the auxiliary magnetic steel can form an ideal protection zone that is long enough to cover the risk area and narrow enough to minimize the bypass effect on the main magnetic circuit, so that the auxiliary magnetic steel has less impact on the magnetic circuit and better inhibits demagnetization.

[0029] Preferably, the widths W1, W2 and W3 of the main magnetic steel 3 and the auxiliary magnetic steel are all not less than 2 mm, and the length ratio X3 = L1:L2 or L1:L3 of the main magnetic steel 3 and the auxiliary magnetic steel satisfies: 8 ≤ X3 ≤ 12. Specifically, the width not less than 2 mm is mainly based on the consideration of mechanical strength and manufacturing process. The magnetic steel is easy to break if it is too thin. The length ratio X3 is limited between 8 and 12, which ensures that the auxiliary magnetic steel has sufficient length to effectively shield the high-risk area of demagnetization at both ends of the main magnetic steel 3, and clearly defines its "auxiliary" status to achieve the maximum protection effect with the minimum volume and control the cost.

[0030] Preferably, the distance D between the angle of the auxiliary magnetic steel close to the center of the rotor and the main magnetic steel 3 satisfies: (n / 3000)²×L / 5+1mm ≤ D ≤ (n / 3000)²×L / 5+2mm, wherein n is the peak speed of the motor, in rpm, and L is the length value of the auxiliary magnetic steel. Specifically, this design ensures that at the peak speed, the core bridge between the auxiliary magnetic steel and the main magnetic steel 3 has sufficient mechanical strength to resist centrifugal force, and can form a high magnetic field density in the area between the auxiliary magnetic steel and the main magnetic steel 3, so that fewer demagnetization field magnetic lines flow through this area, further reducing the risk of demagnetization. At the same time, the floating range of 1mm~2mm accurately controls the magnetic field density in this area, which can form an effective magnetic resistance barrier and avoid excessive saturation.

[0031] Preferably, the minimum distance D2 between the main magnetic steel slot 5 and the outer circle of the rotor is, the minimum distance D3 between the auxiliary magnetic steel slot 6 and the outer circle of the rotor is, and the ratio X4 = D2:D3 satisfies: 0.95 ≤ X4 ≤ 1.1. Specifically, D2 and D3 determine the thickness of the "magnetic bridge", and controlling the ratio to be close to 1 means that the depth of the main and auxiliary magnetic steel slots is coordinately designed, which helps to balance the leakage of the main magnetic field and the auxiliary magnetic field to the outside, avoids the increase of leakage due to the auxiliary magnetic steel slot 6 being too shallow, and avoids the weakening of the overall mechanical strength of the rotor lamination due to being too deep, and is a balanced design considering efficiency and strength.

[0032] Preferably, the total volume of the auxiliary magnetic steel accounts for 3% to 5% of the total volume of the main magnetic steel 3, and specifically, the ratio is very small, which controls the cost increase brought by samarium-cobalt material at a very low level, so that the scheme has very high commercial application value and market competitiveness.

[0033] Advantages: 1. High efficiency anti-demagnetization, significantly improved reliability: The core of the present application is to skillfully set high-coercivity and high-thermal-stability samarium-cobalt auxiliary magnetic steel at the tip corner area of the main magnetic steel 3 of the traditional V-shaped permanent magnet rotor, which is most prone to demagnetization. The magnetic permeability of samarium-cobalt material is close to air, which can form a high-magnetic-resistance "barrier" in this area; when the motor is in harsh working conditions such as high temperature and overload, the strong reverse demagnetizing magnetic field generated by the stator will preferentially pass through the path with lower magnetic resistance, thereby being hindered and shunted by this layer of "barrier", significantly reducing the demagnetizing magnetic field strength acting on the dangerous area of the neodymium-iron-boron main magnetic steel 3, and fundamentally inhibiting the occurrence of irreversible demagnetization. The use of this structure can improve the anti-demagnetization ability of the rotor by more than 13%.

[0034] 2. Main performance is maintained with minimal impact: Instead of simply increasing the amount of magnetic steel, the present application optimizes the electromagnetic design and parameters to minimize the impact of the introduction of auxiliary magnetic steel on the main performance indicators of the motor (such as output torque, power density, and no-load back EMF) and magnetic field distribution (such as torque ripple and magnetic field sinusoidal degree). The size, position, and angle of the auxiliary magnetic steel are optimized to ensure that it plays a magnetic protection role while not sacrificing the core power performance of the motor.

[0035] 3. Excellent cost control, high cost performance: Although the unit price of samarium-cobalt material is higher than that of neodymium-iron-boron, the amount used in the present application is very small, accounting for only 3% to 5% of the total volume of the main magnetic steel 3, so that the overall material cost of the motor increases slightly while the performance is significantly improved, which has very high commercial value.

[0036] 4. Good processability, easy to implement: The size design of the auxiliary magnetic steel slot 6 (such as a gap of L / 200, W / 50) fully considers the lamination mold strength and magnetic steel embedding process in mass production, ensuring that the magnetic steel can be installed smoothly, and avoiding the invalid increase of magnetic resistance due to too large gap, and taking into account the manufacturing feasibility and electromagnetic efficiency.

[0037] 5. The comprehensive performance is optimized, and the robustness is high: by setting a series of related parameters such as a specific angle of the auxiliary magnetic steel and the main magnetic steel 3, a length-width ratio, a distance ratio and a slot depth ratio, the application achieves the best balance among multiple targets such as suppression of demagnetization, maintenance of a magnetic field waveform, guarantee of mechanical strength and reduction of magnetic flux leakage, so that the comprehensive operation robustness (reliability) of the motor under extreme working conditions such as high speed and high temperature is comprehensively enhanced.

[0038] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. A rotor topology to prevent demagnetization of a magnetic steel, characterized by: The rotor core has a plurality of magnetic poles, and a main magnetic steel slot is arranged in a V-shaped symmetrical manner under the same magnetic pole, and a main magnetic steel made of neodymium iron boron material is embedded in the main magnetic steel slot, and an auxiliary magnetic steel slot is arranged near the two ends of the main magnetic steel close to the rotor outer circle direction, and a auxiliary magnetic steel made of samarium cobalt material is embedded in the auxiliary magnetic steel slot, and the auxiliary magnetic steel is used to increase the local magnetic resistance of the area where it is located, so as to inhibit the demagnetization of the end of the main magnetic steel.

2. A rotor topology to prevent demagnetization of a magnetic steel according to claim 1, characterized in that: The main magnetic steel and the auxiliary magnetic steel are both rectangular, and the magnetizing direction of the auxiliary magnetic steel is the same as that of the main magnetic steel.

3. A rotor topology to prevent demagnetization of magnetic steel according to claims 1 and 2, characterized in that: The length gap distance between the auxiliary magnetic steel and the auxiliary magnetic steel slot is L / 200, and the width gap distance is W / 50, wherein L is the length value of the auxiliary magnetic steel, and W is the width value of the auxiliary magnetic steel.

4. A rotor topology to prevent demagnetization of a magnetic steel according to claim 3, characterized in that: Among the two auxiliary magnetic steels, the auxiliary magnetic steel close to the rotor outer circle is the first auxiliary magnetic steel, and the other is the second auxiliary magnetic steel, the included angle A2 between the first auxiliary magnetic steel and the main magnetic steel satisfies: -5°≤ A2 ≤ 5°, and the included angle A3 between the second auxiliary magnetic steel and the main magnetic steel satisfies: -4°≤ A3 ≤ 6°.

5. A rotor topology to prevent demagnetization of a magnetic steel according to claim 4, characterized in that: The shape aspect ratio X1 = L2:W2 of the first auxiliary magnetic steel satisfies: 1.5 ≤ X1 ≤ 5, wherein L2 is the length value of the first auxiliary magnetic steel, and W2 is the width value of the first auxiliary magnetic steel; the shape aspect ratio X2 = L3:W3 of the second auxiliary magnetic steel satisfies: 2.5 ≤ X2 ≤ 5, wherein L3 is the length value of the second auxiliary magnetic steel, and W3 is the width value of the second auxiliary magnetic steel.

6. A rotor topology to prevent demagnetization of a magnetic steel according to claim 1 or 2, characterized in that: The widths W1, W2 and W3 of the main magnetic steel and the auxiliary magnetic steel are all not less than 2mm, and the length ratio X3 = L1: L2 or L1: L3 of the main magnetic steel and the auxiliary magnetic steel satisfies: 8 ≤ X3 ≤ 12.

7. A rotor topology to prevent demagnetization of a magnetic steel according to claim 1 or 2, characterized in that: The distance D between the angle close to the rotor center of the auxiliary magnetic steel and the main magnetic steel satisfies: (n / 3000)² × L / 5 + 1mm ≤ D ≤ (n / 3000)² × L / 5 + 2mm, wherein the peak speed of the motor is n, the unit is rpm, and L is the length value of the auxiliary magnetic steel.

8. A rotor topology to prevent demagnetization of a magnetic steel according to claim 1 or 2, characterized in that: The minimum distance between the main magnetic steel slot and the rotor outer circle is D2, and the minimum distance between the auxiliary magnetic steel slot and the rotor outer circle is D3, and the ratio X4 = D2: D3 satisfies: 0.95 ≤ X4 ≤ 1.

1.

9. A rotor topology to prevent demagnetization of a magnetic steel according to claim 1 or 2, characterized in that: The total volume of the auxiliary magnetic steel accounts for 3% to 5% of the total volume of the main magnetic steel.

Images