A low-loss variable flux magnetic gear

Abstract

The present invention discloses a low-loss variable-flux magnetic gear, belonging to the field of magnetic gear technology. The gear comprises a rotating shaft, a coaxially arranged outer stator, a low-speed rotor, and a high-speed rotor. The high-speed rotor is fixed to the rotating shaft, the low-speed rotor is fixed to the outer surface of the high-speed rotor, and the outer stator is fixed to the outer surface of the low-speed rotor. The outer stator comprises an outer stator core fixed to the low-speed rotor, and an excitation winding, low-coercivity permanent magnets, and high-coercivity permanent magnets embedded within the outer stator core. The low-speed rotor comprises magnetic adjustment blocks and non-magnetic material evenly distributed alternately with the magnetic adjustment blocks. The high-speed rotor comprises a high-speed rotor core fixed to the rotating shaft and high-coercivity permanent magnets embedded within the high-speed rotor core. The present invention can reduce high-speed losses of the magnetic gear by changing the magnetization level of the magnetic gear, thereby improving the output performance of the magnetic gear motor transmission system.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic gears, and in particular relates to a low-loss variable magnetic flux magnetic gear. Background Art

[0002] Magnetic gears have advantages such as high torque density, overload protection, and low noise, and are gradually being used in various fields. Magnetic gears use magnetic blocks to modulate the magnetomotive force of the inner and outer rotor permanent magnets with different pole pairs into the same working harmonic magnetomotive force. Therefore, the magnetic density harmonic content in the inner and outer air gaps is rich. When the magnetic gear rotates at high speed, the iron loss will increase sharply, resulting in increased temperature rise and reduced efficiency. In order to reduce the loss of magnetic gears, the existing technology mainly improves the magnetomotive force distribution of the magnetic gear by adjusting the permanent magnet pole arc coefficient, changing the permanent magnet magnetization method, pole pairing, skewing the poles, etc., to reduce the harmonics of the magnetomotive force and thus reduce the loss of the magnetic gear. In addition, the air gap magnetic permeance distribution can be changed by permanent magnet / rotor modification, auxiliary slots, etc., thereby reducing the loss of the magnetic gear. However, the existing technology will reduce the maximum output torque of the magnetic gear while reducing the magnetomotive force harmonics; changing the air gap magnetic permeance distribution or adopting a complex magnetization method can suppress the harmonics of the magnetic gear, but it will also increase the manufacturing difficulty.

[0003] Therefore, it is urgent to invent a new low-loss variable flux magnetic gear to solve the above problems. Summary of the Invention

[0004] The present invention discloses a low-loss variable magnetic flux magnetic gear. Under low-speed working conditions, the magnetization level of low-coercive force permanent magnets can be increased by excitation current pulses, thereby improving the torque output capacity of the magnetic gear motor transmission system; under high-speed working conditions, the magnetization level of low-coercive force permanent magnets and air gap flux density can be reduced by demagnetization current pulses, thereby reducing the loss of the magnetic gear, thereby effectively solving at least one technical problem involved in the background technology.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A low-loss variable magnetic flux magnetic gear comprises a rotating shaft and a coaxially arranged outer stator, a low-speed rotor and a high-speed rotor, wherein the high-speed rotor is fixed on the rotating shaft, the low-speed rotor is fixed on the outer surface of the high-speed rotor, and the outer stator is fixed on the outer surface of the low-speed rotor. The outer stator comprises an outer stator core, an excitation winding, a low-coercive force permanent magnet and a high-coercive force permanent magnet, wherein the low-coercive force permanent magnet is embedded in a wide slot of the outer stator core, and the high-coercive force permanent magnet is embedded in a wide slot of the outer stator core. The excitation winding is embedded in a narrow slot on both sides of the low-coercive force permanent magnet. The low-speed rotor includes a magnetic adjustment block and a non-magnetic material alternately and evenly distributed with the magnetic adjustment block. The high-speed rotor includes a high-speed rotor core and a high-coercive force permanent magnet embedded in the high-speed rotor core. Under low-speed working conditions, an excitation current is passed through the excitation winding to increase the magnetization level of the low-coercive force permanent magnet. Under high-speed working conditions, a demagnetization current is passed through the excitation winding to reduce the magnetization level of the low-coercive force permanent magnet.

[0007] As a preferred improvement of the present invention, the outer stator core is fixed to the outer surface of the low-speed rotor, and the high-speed rotor core is fixed to the rotating shaft.

[0008] As a preferred improvement of the present invention, the excitation winding, the low coercive force permanent magnet and the high coercive force permanent magnet are evenly distributed along the circumferential direction of the outer stator core in an arrangement of excitation winding-low coercive force permanent magnet-excitation winding-high coercive force permanent magnet.

[0009] As a preferred improvement of the present invention, there are multiple magnetic tuning blocks and multiple non-magnetic conductive materials, and the multiple magnetic tuning blocks and the non-magnetic conductive materials are alternately and evenly distributed along the circumferential direction of the low-speed rotor.

[0010] As a preferred improvement of the present invention, a plurality of slots are provided on the high-speed rotor core, and a plurality of the high-coercive-force permanent magnets are installed in the slots.

[0011] As a preferred improvement of the present invention, the high-speed rotor and the rotating shaft are fixed by interference fit.

[0012] The beneficial effects of the present invention are as follows:

[0013] The magnetic poles of the magnetic gear provided by the present invention are composed of high-coercive force permanent magnets and low-coercive force permanent magnets. DC excitation windings are embedded on both sides of the low-coercive force permanent magnets. Under low-speed working conditions, the magnetization level of the low-coercive force permanent magnets can be increased by excitation current pulses, thereby improving the torque output capacity of the magnetic gear motor transmission system; under high-speed working conditions, the magnetization level of the low-coercive force permanent magnets can be reduced by demagnetization current pulses, thereby reducing the air gap flux density of the magnetic gear and further reducing the loss of the magnetic gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0015] Figure 1 This is a structural schematic diagram of a low-loss variable flux magnetic gear according to the present invention;

[0016] Figure 2 This is a schematic diagram of the working principle of a low-loss variable flux magnetic gear of the present invention;

[0017] Figure 3 This is a loss diagram of a low-loss variable flux magnetic gear of the present invention, wherein: Figure 3 (a) is a schematic diagram of the core loss of the magnetic gear. Figure 3 (b) is a schematic diagram of eddy current loss of permanent magnets in magnetic gears.

[0018] In the figure: 1. Outer stator; 11. Outer stator core; 12. Excitation winding; 13. Low-coercivity permanent magnet; 14. High-coercivity permanent magnet; 2. Low-speed rotor; 21. Magnetic adjustment block; 22. Non-magnetic material; 3. High-speed rotor; 31. High-speed rotor core; 32. High-coercivity permanent magnet. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0021] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0022] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] Example 1

[0025] like Figure 1 As shown, the present invention provides a low-loss variable magnetic flux magnetic gear, including a rotating shaft 4 and a coaxially arranged outer stator 1, a low-speed rotor 2 and a high-speed rotor 3, wherein the high-speed rotor 3 is fixed on the rotating shaft 4, the low-speed rotor 2 is fixed on the outer surface of the high-speed rotor 3, and the outer stator 1 is fixed on the outer surface of the low-speed rotor 2.

[0026] The outer stator 1 includes an outer stator core 11, an excitation winding 12, low-coercive-force permanent magnets 13, and high-coercive-force permanent magnets 14. The outer stator core 11 is fixed to the outer surface of the low-speed rotor 2. The low-coercive-force permanent magnets 13 are embedded in the wide slots of the outer stator core 11, the high-coercive-force permanent magnets 14 are embedded in the narrow slots of the outer stator core 11, and the excitation winding 12 is embedded on both sides of the low-coercive-force permanent magnets 13. Specifically, the excitation winding 12, the low-coercive-force permanent magnets 13, and the high-coercive-force permanent magnets 13 are evenly distributed along the circumference of the outer stator core 11 in the arrangement of excitation winding - low-coercive-force permanent magnets - excitation winding - high-coercive-force permanent magnets.

[0027] The low-speed rotor 2 includes a magnetic tuning block 21 and a non-magnetic conductive material 22 . There are multiple magnetic tuning blocks 21 and multiple non-magnetic conductive materials 22 . The multiple magnetic tuning blocks 21 and the non-magnetic conductive materials 22 are alternately and evenly distributed along the circumferential direction of the low-speed rotor 2 .

[0028] The high-speed rotor 3 includes a high-speed rotor core 31 and high-coercivity permanent magnets 32 embedded in the high-speed rotor core 31. The high-speed rotor core 31 is fixed to the rotating shaft 4 by an interference fit. Preferably, the high-speed rotor core 31 is provided with a plurality of slots, and the plurality of high-coercivity permanent magnets 32 are mounted in the slots.

[0029] Example 2

[0030] like Figure 2 Figure 1 is a schematic diagram illustrating the operating principle of a low-loss variable-flux magnetic gear according to the present invention. The magnetic poles are composed of low-coercivity permanent magnets 13 and high-coercivity permanent magnets 14. When the magnetic gear motor transmission system operates at low speed, a brief excitation current is passed through the excitation winding 12, causing the operating point of the low-coercivity permanent magnets 13 to reach point E. After the excitation process is complete, the operating point of the low-coercivity permanent magnets 13 moves along line AE to point A, which represents the post-magnetization operating point. At this point, the magnetization level of the low-coercivity permanent magnets 13 is increased, improving torque output capability and enabling the magnetic gear to output high torque.

[0031] When the magnetic gear motor transmission system operates at high speed, a short demagnetization current is passed through the excitation winding 12, and the working point of the low-coercive-force permanent magnet 13 moves to point B along the curve AKB. After the demagnetization process is completed, the working point of the low-coercive-force permanent magnet 13 moves to point C along the straight line BD. Point C is the working point after demagnetization. At this time, the magnetization level of the low-coercive-force permanent magnet 13 is reduced, and the magnetic flux density in the air gap of the magnetic gear is also reduced. Therefore, its loss under high-speed operation will also be reduced.

[0032] Example 3

[0033] like Figure 3 As shown in the figure, the iron loss and eddy current loss of the permanent magnet of the magnetic gear increase with the increase of the speed. At the same speed, the demagnetization current has little effect on the core loss of the magnetic gear. However, the larger the demagnetization current, the lower the eddy current loss of the permanent magnet. This shows that reducing the magnetization level of the low coercive force permanent magnet can significantly reduce the total loss of the magnetic gear.

[0034] The beneficial effects of the present invention are as follows:

[0035] The magnetic poles of the magnetic gear provided by the present invention are composed of high-coercive force permanent magnets and low-coercive force permanent magnets. DC excitation windings are embedded on both sides of the low-coercive force permanent magnets. Under low-speed working conditions, the magnetization level of the low-coercive force permanent magnets can be increased by excitation current pulses, thereby improving the torque output capacity of the magnetic gear motor transmission system; under high-speed working conditions, the magnetization level of the low-coercive force permanent magnets can be reduced by demagnetization current pulses, thereby reducing the air gap flux density of the magnetic gear and further reducing the loss of the magnetic gear.

[0036] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A low-loss variable flux magnetic gear, characterized in that: The invention comprises a rotating shaft and a coaxially arranged outer stator, a low-speed rotor and a high-speed rotor, wherein the high-speed rotor is fixed on the rotating shaft, the low-speed rotor is fixed on the outer surface of the high-speed rotor, and the outer stator is fixed on the outer surface of the low-speed rotor. The outer stator comprises an outer stator core, an excitation winding, a low-coercive force permanent magnet and a high-coercive force permanent magnet, wherein the low-coercive force permanent magnet is embedded in the wide slot of the outer stator core, the high-coercive force permanent magnet is embedded in the narrow slot of the outer stator core, the excitation winding is embedded on both sides of the low-coercive force permanent magnet, and the excitation winding, the low-coercive force permanent magnet and the high-coercive force permanent magnet are fixed on the outer surface of the low-coercive force permanent magnet. The high-coercive force permanent magnets are evenly distributed along the circumferential direction of the outer stator core in the arrangement of excitation winding-low-coercive force permanent magnets-excitation winding-high-coercive force permanent magnets; the low-speed rotor includes magnetic adjustment blocks and non-magnetic conductive materials that are alternately and evenly distributed with the magnetic adjustment blocks; the high-speed rotor includes a high-speed rotor core and high-coercive force permanent magnets embedded in the high-speed rotor core; under low-speed operating conditions, an excitation current is passed through the excitation winding to increase the magnetization level of the low-coercive force permanent magnets; under high-speed operating conditions, a demagnetization current is passed through the excitation winding to reduce the magnetization level of the low-coercive force permanent magnets.

2. A low-loss variable flux magnetic gear according to claim 1, characterized in that: The outer stator core is fixed to the outer surface of the low-speed rotor, and the high-speed rotor core is fixed to the rotating shaft.

3. The low-loss variable flux magnetic gear according to claim 1, characterized in that: There are a plurality of magnetic adjustment blocks and a plurality of non-magnetic conductive materials, and the plurality of magnetic adjustment blocks and the non-magnetic conductive materials are alternately and evenly distributed along the circumferential direction of the low-speed rotor.

4. The low-loss variable flux magnetic gear according to claim 1, characterized in that: A plurality of slots are provided on the high-speed rotor core, and a plurality of high-coercive-force permanent magnets are installed in the slots.

5. The low-loss variable flux magnetic gear according to claim 1, characterized in that: The high-speed rotor and the rotating shaft are fixed by interference fit.

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