Permanent magnet for induction heating device and design method thereof

Abstract

The invention relates to the field of metal rod heating, in particular to a permanent magnet for an induction heating device and a design method, the permanent magnet is annular and comprises a plurality of permanent magnet units distributed in the circumferential direction, and each permanent magnet unit comprises a first magnetic block, a second magnetic block, a third magnetic block, a fourth magnetic block, a fifth magnetic block and a sixth magnetic block which are sequentially arranged clockwise; the magnetizing direction of the first magnetic block points to the outer side of the permanent magnet and deflects clockwise by a preset angle a in the radial direction of the permanent magnet, the magnetizing direction of the second magnetic block points clockwise in the circumferential direction of the permanent magnet, and the magnetizing direction of the third magnetic block points to the inner side of the permanent magnet and deflects anticlockwise by a preset angle a in the radial direction of the permanent magnet. The magnetizing direction of the fourth magnetic block points to the inner side of the permanent magnet and deflects clockwise by a preset angle a in the radial direction of the permanent magnet, the magnetizing direction of the fifth magnetic block points anticlockwise in the circumferential direction of the permanent magnet, and the magnetizing direction of the sixth magnetic block points to the outer side of the permanent magnet and deflects anticlockwise by a preset angle a in the radial direction of the permanent magnet.

Description

Technical Field

[0001] This application relates to the field of induction heating technology, and in particular to a permanent magnet for an induction heating device and its design method. Background Technology

[0002] Traditional induction heating technology heats workpieces by generating eddy currents in the workpiece using alternating current, but it has the following problems:

[0003] 1. Uneven magnetic field distribution: The magnetic field generated by conventional coils decays rapidly in space, resulting in uneven heating areas.

[0004] 2. High energy consumption: It requires a large current to maintain a strong magnetic field, resulting in low efficiency.

[0005] Halbach array permanent magnets have advantages such as sinusoidal magnetic field distribution, self-shielding effect, high fundamental wave field, low harmonic content, and strong unilateral magnetic field, but their application in induction heating is still immature and needs further development. Summary of the Invention

[0006] This application provides a permanent magnet for an induction heating device and its design method, in order to solve the problems of uneven magnetic field distribution and high energy consumption in the prior art.

[0007] On the one hand, this application provides a permanent magnet for an induction heating device. The permanent magnet has a ring structure and includes a plurality of permanent magnet units distributed along the circumference. Each permanent magnet unit includes a first magnetic block, a second magnetic block, a third magnetic block, a fourth magnetic block, a fifth magnetic block, and a sixth magnetic block arranged in a clockwise order.

[0008] The magnetization direction of the first magnetic block is to point outward from the permanent magnet and deflect clockwise by a preset angle α along the radial direction of the permanent magnet. The magnetization direction of the second magnetic block is to point clockwise along the circumference of the permanent magnet. The magnetization direction of the third magnetic block is to point inward from the permanent magnet and deflect counterclockwise by a preset angle α along the radial direction of the permanent magnet. The magnetization direction of the fourth magnetic block is to point inward from the permanent magnet and deflect clockwise by a preset angle α along the radial direction of the permanent magnet. The magnetization direction of the fifth magnetic block is to point counterclockwise along the circumference of the permanent magnet. The magnetization direction of the sixth magnetic block is to point outward from the permanent magnet and deflect counterclockwise by a preset angle α along the radial direction of the permanent magnet.

[0009] In one possible design, the preset angle α is 0°-90°.

[0010] In one possible design, the preset angle α is 25°-45°.

[0011] In one possible design, the preset angle α is 30°-40°.

[0012] In one possible design, the preset angle α is 35°.

[0013] In one possible design, each permanent magnet includes 2-5 permanent magnet units arranged circumferentially.

[0014] In one possible design, each permanent magnet includes three permanent magnet units arranged circumferentially.

[0015] In one possible design, the cross-sections of the first, second, third, fourth, fifth, and sixth magnetic blocks are all set as fan-shaped rings, and the radial thickness of the first, second, third, fourth, fifth, and sixth magnetic blocks is set as a preset thickness of 35mm-45mm.

[0016] On the other hand, this application also provides a design method for a permanent magnet for an induction heating device, comprising:

[0017] Based on the relationship between air gap magnetic flux density, heating power and the number of pole pairs, a permanent magnet is divided into p poles, where the number of poles p satisfies: 2≤p≤5 and p is an integer.

[0018] Based on the magnetization characteristics of the Halbach array, a magnetic pole is divided into m magnetic blocks and into two groups, with the number of magnetic blocks m satisfying: m = 2p;

[0019] The magnetization angles of p adjacent magnetic blocks in a set of magnetic blocks are parametrically calculated in the radial direction at 0°, 90°, 180° and 270° respectively, and the basic magnetization angle is determined according to the principle of maximizing heating power.

[0020] Based on the basic magnetization angle, the magnetization angles of multiple magnetic blocks in a set of magnetic blocks are parametrically calculated between -90° and 90°, and the optimal magnetization angle is determined according to the principle of maximizing heating power.

[0021] In one possible design, the design method for the permanent magnet used in the induction heating device includes:

[0022] Based on the relationship between air gap magnetic flux density, heating power and the number of magnetic pole pairs, a permanent magnet can be divided into 3 magnetic poles.

[0023] Based on the magnetization characteristics of the Halbach array, a magnetic pole is divided into 6 magnetic blocks and then into two groups.

[0024] The magnetization angles of three adjacent magnetic blocks in a set of magnetic blocks are parametrically calculated in the radial direction at 0°, 90°, 180° and 270° respectively, and the basic magnetization angle is determined according to the principle of maximizing heating power.

[0025] Based on the basic magnetization angle, the magnetization angles of the two magnetic blocks on both sides of a set of magnetic blocks are parametrically calculated between -90° and 90°, and the optimal magnetization angle is determined according to the principle of maximizing heating power.

[0026] The beneficial effects of this application are as follows:

[0027] With equal aluminum rod mass, length, amount of permanent magnets, length of magnetic cylinder, and length of air gap, and with only the magnetization direction controlled, compared to the traditional Halbach array and the 35° radial angle magnetization array, the 35° radial angle magnetization array generates a stronger air gap magnetic field, resulting in higher heating power for the aluminum rod and faster heating of the aluminum rod to the same temperature. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a permanent magnet for an induction heating device provided in an embodiment of this application;

[0030] Figure 2 A graph showing the relationship between heating power and number of pole pairs for an aluminum rod;

[0031] Figure 3 The figure shows the rough parameterized simulation results of three magnetic blocks for one magnetic pole;

[0032] Figure 4 A schematic diagram of a magnetized structure for a six-cycle 3-pole-pair Halbach array;

[0033] Figure 5 A diagram showing the parameterized data processing for the radial magnetization angle;

[0034] Figure 6a Cross-sectional view of the magnetization direction of a conventional Halbach array for permanent magnets;

[0035] Figure 6b Optimize the magnetization direction cross-section of the Halbach array of permanent magnets at 35°;

[0036] Figure 7a This is a diagram showing the distribution of magnetic field lines and magnetic density cloud patterns in a traditional Halbach array for permanent magnets.

[0037] Figure 7b Optimized magnetization magnetic field lines and magnetic density cloud distribution for a 35° Halbach array of permanent magnets;

[0038] Figure 8 A comparison chart of heating power of aluminum rods under different permanent magnet arrays;

[0039] Figure 9 Heating effect diagram of traditional Halbach array;

[0040] Figure 10 Graph showing the optimized magnetization heating effect at 35°;

[0041] Figure 11 This is a diagram of the magnetization scheme for Example 1;

[0042] Figure 12 This is a diagram of the magnetization scheme for Example 2;

[0043] Figure 13 This is a diagram of the magnetization scheme for Example 3;

[0044] Figure 14 This is a diagram of the magnetization scheme for Example 4;

[0045] Figure 15 This is a diagram of the magnetization scheme in Example 5;

[0046] Figure 16 This is a diagram of the magnetization scheme in Example 6;

[0047] Figure 17 This is a comparison chart of heating power for control group 1;

[0048] Figure 18 This is a comparison chart of heating power for control group 2;

[0049] Figure 19 This is a comparison chart of heating power for control group 3.

[0050] Figure label:

[0051] 1. First magnetic block; 2. Second magnetic block; 3. Third magnetic block; 4. Fourth magnetic block; 5. Fifth magnetic block; 6. Sixth magnetic block; 7. Metal rod. Detailed Implementation

[0052] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] The following is combined with Figures 1-16 This describes a permanent magnet for an induction heating device provided in an embodiment of this application. (Refer to...) Figure 1As shown, the permanent magnet has a ring structure, comprising multiple permanent magnet units distributed circumferentially. Each permanent magnet unit includes six permanent magnet blocks, with three permanent magnet blocks fixed together. Each permanent magnet unit includes a first magnetic block 1, a second magnetic block 2, a third magnetic block 3, a fourth magnetic block 4, a fifth magnetic block 5, and a sixth magnetic block 6 arranged clockwise. The magnetization direction of the first magnetic block 1 is towards the outside of the permanent magnet and deflected clockwise by a preset angle α along the radial direction of the permanent magnet; the magnetization direction of the second magnetic block 2 is clockwise along the circumference of the permanent magnet; the magnetization direction of the third magnetic block 3 is towards the inside of the permanent magnet and deflected counterclockwise by a preset angle α along the radial direction of the permanent magnet; the magnetization direction of the fourth magnetic block 4 is towards the inside of the permanent magnet and deflected clockwise by a preset angle α along the radial direction of the permanent magnet; the magnetization direction of the fifth magnetic block 5 is counterclockwise along the circumference of the permanent magnet; and the magnetization direction of the sixth magnetic block 6 is towards the outside of the permanent magnet and deflected counterclockwise by a preset angle α along the radial direction of the permanent magnet. By adopting the above-mentioned magnetization direction, the magnetic field generated by the permanent magnet unit can cooperate with each other in the circumferential and radial directions, forming a magnetic field distribution that is more conducive to the induction heating of the metal rod 7, thereby further improving the heating efficiency and uniformity.

[0054] The preset angle α ranges from 0° to 90°. In practical applications, to achieve better heating results, the preset angle α is preferably 25°-45°, and more preferably 30°-40°. Within this angle range, the distribution and intensity of the magnetic field can better meet the induction heating requirements of the metal rod 7, effectively improving heating efficiency and uniformity.

[0055] In one embodiment of the present invention, the preset angle α is 35°, and the magnetization direction is 35°, which can not only improve the heating efficiency and uniformity, but also increase the heating power.

[0056] In some embodiments, each permanent magnet includes 2-5 permanent magnet units arranged circumferentially in sequence. More preferably, each permanent magnet includes 3 permanent magnet units arranged circumferentially in sequence. By reasonably selecting the number of permanent magnet units, it is possible to balance the structural complexity and manufacturing cost of the device while ensuring the magnetic field strength and uniformity, and to ensure that the heating power reaches the optimal level.

[0057] To facilitate installation and ensure magnetic field stability, the cross-sections of the first magnetic block 1, second magnetic block 2, third magnetic block 3, fourth magnetic block 4, fifth magnetic block 5, and sixth magnetic block 6 are all designed as fan-shaped annular sections. The first magnetic block 1, second magnetic block 2, and third magnetic block 3 are fixed as one group, and the fourth magnetic block 4, fifth magnetic block 5, and sixth magnetic block 6 are fixed as another group. Simultaneously, the radial thickness of the first magnetic block 1, second magnetic block 2, third magnetic block 3, fourth magnetic block 4, fifth magnetic block 5, and sixth magnetic block 6 is set to a preset thickness of 35mm-45mm. Within this thickness range, the magnetic blocks possess sufficient magnetic properties to ensure heating cycle time while simultaneously reducing the material cost of the permanent magnet.

[0058] This application also provides a design method for a permanent magnet in an induction heating device, the method specifically being:

[0059] Step 1: Based on the relationship between air gap magnetic flux density, heating power and the number of magnetic pole pairs, a permanent magnet is divided into p magnetic poles, where the number of magnetic poles p satisfies: 2≤p≤5 and p is an integer.

[0060] Specifically, in the design of permanent magnet structures, an excessive number of pole pairs may reduce the magnetic flux shared by each pole, ultimately leading to a decrease in the air gap magnetic flux density generated by the permanent magnet at the air gap. In permanent magnet design, the fundamental magnetic flux of the air gap magnetic field has a significant impact on the air gap magnetic flux density. The relationship between the amplitude of the fundamental magnetic flux density and the number of poles is as follows:

[0061]

[0062] In the formula: p is the number of magnetic poles; B is the remanence of the permanent magnet; hm is the thickness of the permanent magnet; δ is the air gap length; μr is the relative permeability of the permanent magnet; σ is the flux leakage coefficient.

[0063] It is known that the more magnetic poles there are, the more likely it is to reduce the magnetic flux density of the air gap. Therefore, the number of magnetic pole pairs should not exceed 6.

[0064] In addition, the heating power generated by the permanent magnet heating aluminum rod is related to the number of pole pairs of the permanent magnet as follows: Figure 2 As shown, when the number of magnetic poles p satisfies 2≤p≤5, the heating power exceeds 450KW, and when the number of magnetic poles p is 3, the heating power of the aluminum rod reaches its maximum value.

[0065] Step 2: Based on the magnetization characteristics of the Halbach array, a magnetic pole is divided into m magnetic blocks and divided into two groups. The number of magnetic blocks m satisfies: m = 2p.

[0066] Specifically, based on the magnetic symmetry of the NS pole pairs in the magnetization characteristics of the Halbach array, a pole pair is often divided into an even number of magnetic blocks for magnetization angle optimization analysis. Considering permanent magnet losses, cost, and structural reliability, the number of magnetic blocks per pole should not exceed eight. For example, when the number of poles p is 3, the number of magnetic blocks m per pole is 6, and these 6 blocks are equally divided into two groups, with each block corresponding to a central angle of 20°.

[0067] Step 3: After determining the number of magnetic blocks for each magnetic pole pair, perform parametric calculations on the magnetization angles of the p adjacent magnetic blocks in a group, using the radial direction as a reference, in the directions of 0°, 90°, 180°, and 270° respectively, and determine the basic magnetization angle based on the principle of maximizing heating power.

[0068] For example, when the number of magnetic poles p is 3 and the number of magnetic blocks m in each magnetic pole is 6, the magnetization angle of 3 adjacent magnetic blocks in a group of magnetic blocks is parametrically calculated in the radial direction at 0°, 90°, 180° and 270° respectively, and the basic magnetization angle is determined according to the principle of maximizing heating power.

[0069] Specific simulation results are as follows Figure 3 As shown, the aluminum rod has the highest heating power when the magnetization directions of the three magnetic blocks in the same group are 0°, 270°, and 180° respectively. That is, the magnetization direction is as follows: Figure 4 As shown, the magnetization direction of the first magnetic block is 0°, the second magnetic block is 270°, and the third magnetic block is 180°. The magnetization directions of the other three magnetic blocks on the same magnetic pole are symmetrically arranged, i.e., the magnetization directions of the three magnetic blocks are 180°, 90°, and 0° respectively. In this configuration, the magnetization array of six magnetic blocks provides the optimal heating effect for the aluminum rod. Therefore, the basic magnetization angles are determined as follows: 0° for the left magnetic block, 270° for the middle magnetic block, and 180° for the right magnetic block.

[0070] Step four: After determining the basic magnetization angle, use the basic magnetization angle as a reference to perform parametric calculations on the magnetization angles of multiple magnetic blocks in a set of magnetic blocks, respectively, between -90° and 90°, and determine the optimal magnetization angle based on the principle of maximizing heating power.

[0071] For example, when the number of magnetic poles p is 3 and the number of magnetic blocks m per pole is 6, the magnetization angles of the left and right magnetic blocks in a set of magnetic blocks are parametrically calculated between -90° and 90°, respectively, and the optimal magnetization angle is determined based on the principle of maximizing heating power. Essentially, the magnetization direction of the middle magnetic block remains constant at the basic magnetization angle, using tangential magnetization; the magnetization directions of the left and right magnetic blocks vary between -90° and 90° based on the basic magnetization angle. To reduce simulation complexity, parametric calculations are performed every 5°, resulting in simulation results as shown below. Figure 5 As shown in the figure, it can be seen that the heating power of the aluminum rod is maximized when the magnetization angles of the left and right magnetic blocks form a 35° angle with the radial direction. The optimal magnetization angle is as follows. Figure 6b As shown.

[0072] The optimized 35° radial oblique magnetization array was compared with the traditional Halbach array (such as... Figure 6a Simulation comparisons were conducted, under the conditions of equal permanent magnet volume, equal magnetic cylinder length, equal aluminum rod mass, equal aluminum rod length, and the same air gap, comparing the magnetic density cloud pattern and magnetic field line distribution around the aluminum rod heated by a traditional Halbach array permanent magnet. Figure 7a As shown, the magnetic field density cloud map and magnetic field line distribution around the aluminum rod heated by the optimized 35° radially angled permanent magnet are as follows: Figure 7bAs shown, magnetization at a 35° radial angle generates a stronger magnetic field around the aluminum rod.

[0073] Simultaneously, the optimized 35° radial oblique angle magnetized array was compared with the traditional Halbach array in simulation, with heating power as follows: Figure 8 As shown, the magnetization heating power of a conventional Halbach array ( Figure 8 The green line in the middle) has a power of only 650kW, while the heating power using the optimized 35° radial bevel magnetization ( Figure 8 (The red line in the middle) can reach 680kW.

[0074] In addition, the heating effect of traditional Halbach arrays is as follows: Figure 9 As shown, the heating effect of the optimized 35° radial oblique angle magnetization array is as follows: Figure 10 As shown, the optimized 35° radial angle magnetized array has a more uniform temperature distribution when heating the aluminum rod. At the same time, when heating to the same temperature, the traditional Halbach array is more than 2 seconds slower than the optimized 35° radial angle magnetized array. Thus, when heating a 7500mm aluminum rod continuously, the traditional Halbach array takes 12-15 seconds to heat each aluminum rod, making it difficult to meet the overall cycle time requirements.

[0075] To verify that the 35° optimized magnetization method of this application achieves the highest permanent magnet heating power, the following comparative experiments were conducted:

[0076] Under optimized magnetization conditions of a 3-pole Halbach array of 18 permanent magnets at 35°, with other parameters kept constant, the heating effect of the optimized array was compared and verified after modifying one parameter. The experimental data are shown in Table 2. Table 2 is a data table comparing and analyzing the heating power of different embodiments by changing parameters such as the number of pole pairs, the number of pole blocks, the central angle corresponding to each pole block, and the magnetization method.

[0077] Table 2 Simulation Comparison Data Table

[0078]

[0079]

[0080] As shown in Table 2, the heating effect of the optimized array was compared and verified using control groups 1, 2, and 3 respectively. The specific analysis is as follows:

[0081] Control group 1:

[0082] Example 1 (refer to) Figure 11 The number of magnetic pole pairs is 3, the number of magnetic pole blocks is 18, the central angle of each magnetic pole block is 20°, the magnetization is optimized at 35°, and the heating power reaches 416kW.

[0083] Example 2 (refer to) Figure 12 Example 1: 3 pole pairs, 12 pole blocks, each pole block corresponding to a central angle of 30°, using a traditional Halbach array for magnetization, with a heating power of 356kW. Compared to Example 1, the number of pole blocks is reduced, the magnetization method is different, and the heating power is decreased.

[0084] Example 3 (refer to) Figure 13 Example 1: Number of magnetic pole pairs 2, number of magnetic pole blocks 12, central angle of each magnetic pole block 30°, optimized magnetization at 35°, heating power 306kW. Compared with Example 1, the number of magnetic pole pairs and the number of magnetic pole blocks are reduced, and the heating power is further reduced.

[0085] Reference Figure 17 Comparing the heating power of Examples 1-3, the heating power of the permanent magnet in Example 2 ( Figure 17 (Middle gray lines), heating power of the permanent magnet in Example 3 ( Figure 17 The yellow lines in the middle are all lower than the heating power of the permanent magnet in Example 1. Figure 17 (The red line in the middle).

[0086] Control group 2:

[0087] Example 1 (refer to) Figure 11 The number of magnetic pole pairs is 3, the number of magnetic pole blocks is 18, the central angle of each magnetic pole block is 20°, the magnetization is optimized at 35°, and the heating power reaches 416kW.

[0088] Example 4 (refer to) Figure 14 ): Number of magnetic pole pairs: 3, Number of magnetic pole blocks: 18, The central angle of the left and right magnetic blocks is 24°, and that of the middle magnetic block is 12°. 35° optimized magnetization is adopted, and the heating power is 402kW.

[0089] Example 5 (refer to) Figure 15 The number of magnetic pole pairs is 3, the number of magnetic pole blocks is 18, the central angle of the left and right magnetic blocks is 15°, and the central magnetic block is 30°. Optimized magnetization at 35° is used, and the heating power is 400kW. Compared with Example 1, these two embodiments change the distribution of the central angles of the magnetic blocks, and the heating power is reduced in both cases.

[0090] Reference Figure 18 The heating power of Examples 1, 4, and 5 was compared, and the heating power of the permanent magnet in Example 4 was ( Figure 18 (The yellow line in the middle), the heating power of the permanent magnet in Example 5 ( Figure 18 The gray lines are all lower than the heating power of the permanent magnet in Example 1. Figure 18 (The red line in the middle).

[0091] Control group 3:

[0092] Example 1 (refer to) Figure 11 The number of magnetic pole pairs is 3, the number of magnetic pole blocks is 18, the central angle of each magnetic pole block is 20°, the magnetization is optimized at 35°, and the heating power reaches 416kW.

[0093] Example 6 (refer to) Figure 16 The magnetization method is as follows: 3 magnetic pole pairs, 18 magnetic pole blocks, and a central angle of 20° for each magnetic pole block. The magnetization method is as follows: the left magnetic block is radially outward, the middle magnetic block is tangential to the right, and the right magnetic block is radially inward. The heating power is 337kW. Compared with Example 1, the heating power is significantly reduced after the magnetization method is changed.

[0094] Reference Figure 19 Comparing the heating power of Examples 1 and 6, the heating power of the permanent magnet in Example 6 ( Figure 19 The heating power of the permanent magnet in Example 1 (as shown in the green line) is lower than that of the permanent magnet in Example 1. Figure 19 (The red line in the middle).

[0095] Based on the experimental results of control groups 1, 2, and 3, among these parameter combinations, the highest heating power was achieved with 3 pole pairs, 18 pole blocks, a central angle of 20° for each pole block, and optimized magnetization at 35°. This indicates that this parameter combination is more conducive to improving the induction heating effect. Furthermore, when the central angle of the permanent magnet was modified, the heating power did not change significantly using the same magnetization method. Therefore, for ease of processing and structural stability, the preferred configuration for the permanent magnet used in the induction heating device is: 3 pole pairs, 18 pole blocks, a central angle of 20° for each pole block, and optimized magnetization at 35°, which provides the highest heating power for the metal rod.

[0096] In practical applications, considering the heating cycle time of the aluminum rod and material costs, the permanent magnet uses 45UH neodymium iron boron material with a radial thickness of 40mm. When used to heat an aluminum rod with a total length of 7500mm, two magnetic cylinders with opposite rotation directions, the same rotation speed, and permanent magnets inside can be used; at the same time, the long aluminum rod is divided into 6 sections for uniform heating, and the actual heating effect is basically consistent with the simulation results.

[0097] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0098] 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 indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0099] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0100] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0101] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A permanent magnet for an induction heating device, characterized in that, The permanent magnet has a ring structure and includes multiple permanent magnet units distributed along the circumference. Each permanent magnet unit includes a first magnetic block, a second magnetic block, a third magnetic block, a fourth magnetic block, a fifth magnetic block, and a sixth magnetic block arranged in a clockwise order. The magnetization direction of the first magnetic block is pointing outward from the permanent magnet and deflected clockwise by a preset angle α along the radial direction of the permanent magnet; the magnetization direction of the second magnetic block is pointing clockwise along the circumference of the permanent magnet; the magnetization direction of the third magnetic block is pointing inward from the permanent magnet and deflected counterclockwise by a preset angle α along the radial direction of the permanent magnet; the magnetization direction of the fourth magnetic block is pointing inward from the permanent magnet and deflected clockwise by a preset angle α along the radial direction of the permanent magnet; the magnetization direction of the fifth magnetic block is pointing counterclockwise along the circumference of the permanent magnet; and the magnetization direction of the sixth magnetic block is pointing outward from the permanent magnet and deflected counterclockwise by a preset angle α along the radial direction of the permanent magnet.

2. The permanent magnet induction heating device according to claim 1, characterized in that, The preset angle α is 0°-90°.

3. The permanent magnet induction heating device according to claim 2, characterized in that, The preset angle α is 25°-45°.

4. The permanent magnet induction heating device according to claim 3, characterized in that, The preset angle α is 30°-40°.

5. The permanent magnet induction heating device according to claim 4, characterized in that, The preset angle α is 35°.

6. The permanent magnet induction heating device according to claim 1, characterized in that, Each of the permanent magnets comprises 2-5 permanent magnet units arranged circumferentially in sequence.

7. The permanent magnet induction heating device according to claim 6, characterized in that, Each of the permanent magnets comprises three permanent magnet units arranged circumferentially in sequence.

8. The permanent magnet induction heating device according to claim 7, characterized in that, The cross-sections of the first, second, third, fourth, fifth, and sixth magnetic blocks are all configured as fan-shaped rings, and the radial thickness of the first, second, third, fourth, fifth, and sixth magnetic blocks is set to a preset thickness of 35mm-45mm.

9. A design method for a permanent magnet used in an induction heating device, characterized in that, include: Based on the relationship between air gap magnetic flux density, heating power and the number of pole pairs, a permanent magnet is divided into p poles, where the number of poles p satisfies: 2≤p≤5 and p is an integer. Based on the magnetization characteristics of the Halbach array, a magnetic pole is divided into m magnetic blocks and into two groups, with the number of magnetic blocks m satisfying: m = 2p; The magnetization angles of p adjacent magnetic blocks in a set of magnetic blocks are parametrically calculated in the radial direction at 0°, 90°, 180° and 270° respectively, and the basic magnetization angle is determined according to the principle of maximizing heating power. Based on the basic magnetization angle, the magnetization angles of multiple magnetic blocks in a set of magnetic blocks are parametrically calculated between -90° and 90°, and the optimal magnetization angle is determined according to the principle of maximizing heating power.

10. The design method for a permanent magnet in an induction heating device according to claim 9, characterized in that, include: Based on the relationship between air gap magnetic flux density, heating power and the number of magnetic pole pairs, a permanent magnet can be divided into 3 magnetic poles. Based on the magnetization characteristics of the Halbach array, a magnetic pole is divided into 6 magnetic blocks and then into two groups. The magnetization angles of three adjacent magnetic blocks in a set of magnetic blocks are parametrically calculated in the radial direction at 0°, 90°, 180° and 270° respectively, and the basic magnetization angle is determined according to the principle of maximizing heating power. Based on the basic magnetization angle, the magnetization angles of the two magnetic blocks on both sides of a set of magnetic blocks are parametrically calculated between -90° and 90°, and the optimal magnetization angle is determined according to the principle of maximizing heating power.

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