Compound magnetic circuit type magnetic gear and pseudo-direct-drive permanent magnet motor

Abstract

The application discloses a composite magnetic circuit type magnetic gear and a pseudo-direct-drive permanent magnet motor, and belongs to the technical field of power transmission. The magnetic gear and the motor both comprise a magnetic steel array with a composite magnetic circuit. The magnetic steel array with the composite magnetic circuit comprises an iron core and a radial magnetization magnetic steel array. The radial magnetization magnetic steel array comprises a plurality of radial magnetization magnetic steels which are distributed at intervals along a circumference, and the magnetization directions of adjacent radial magnetization magnetic steels are opposite. The radial magnetization magnetic steels are partially embedded in the iron core, the embedded parts are polygonal shapes which are symmetrical about the radial direction, and the widths of the embedded parts gradually decrease along the embedding direction. The iron core is provided with accommodating grooves which are matched with the embedded parts of the radial magnetization magnetic steels. The application can optimize the magnetic circuit design of the concentric magnetic gear, improve the torque transmission capacity of the magnetic gear, and improve the maximum output torque of the pseudo-direct-drive permanent magnet motor with the magnetic gear.

Description

Technical Field

[0001] This invention belongs to the field of power transmission technology, and more specifically, relates to a composite magnetic circuit type magnetic gear and a pseudo-direct drive permanent magnet motor. Background Technology

[0002] Unlike traditional mechanical gears, concentric magnetic gears have advantages such as frictionless operation, low noise, and built-in overload protection. Based on the principle of magnetic field modulation, concentric magnetic gears have high utilization of permanent magnets and torque density comparable to traditional mechanical gears, showing promising prospects for industrial applications.

[0003] Concentric magnetic gears can be combined with permanent magnet synchronous motors to form pseudo-direct-drive permanent magnet motors, also known as magnetic gear composite motors. Because these motors have an embedded reduction magnetic gear, their mechanical ends naturally exhibit the characteristics of "low speed, high torque," making them highly promising for direct-drive applications in aerospace, oilfield development, electric vehicle traction, and new energy power generation. By sharing components, pseudo-direct-drive permanent magnet motors can significantly reduce the size of traditional "motor + gearbox" electric drive systems.

[0004] Concentric magnetic gears have the characteristic of maximum torque transmission, which depends on the magnetizing capacity of their permanent magnet array. The maximum output torque of a pseudo-direct-drive permanent magnet motor containing concentric magnetic gears depends entirely on the maximum torque transmitted by the magnetic gears. Therefore, optimizing the magnetic circuit design of concentric magnetic gears, reducing magnetic leakage, and increasing the fundamental amplitude of the air gap magnetic flux density are of great significance for improving the torque transmission capacity of magnetic gears and the maximum output torque of pseudo-direct-drive permanent magnet motors containing concentric magnetic gears.

[0005] Patent CN202211182419.4 proposes a magnetic gear with multiple embedded irregularly shaped magnets. The magnet array has magnets in multiple magnetization directions, causing the magnetic field to concentrate on the outside of the rotor, resulting in a larger magnetic flux on one side and thus improving the torque transmission capability of the magnetic gear. However, its N and S poles are asymmetrical, causing large even-order and low-order harmonics in the air gap, which is detrimental to losses and torque pulsation. Patent CN202211182479.6 proposes a magnetic gear with an embedded inner magnetic ring. It uses a V-shaped magnet array to improve the magnetization effect of the permanent magnet array and enhance the magnetic field strength of the outer magnetic ring. However, to ensure mechanical strength, magnetic bridges must be set between the magnets, resulting in significant magnetic leakage and low magnetic field utilization, which is not conducive to further improving the torque transmission capability of the magnetic gear. Patent CN202011327962.X proposes a vernier magnetic gear composite motor with an alternating pole Halbach magnet array. The high-speed rotor adopts a double-layer Halbach alternating pole magnet array, which has high working magnetic flux density and magnet utilization rate of the magnetic gear, resulting in high torque density. However, this structure contains three layers of air gaps, making it relatively complex.

[0006] Overall, the magnetic circuit design of existing magnetic gears and pseudo-direct drive permanent magnet motors with them is relatively simple, with low magnet utilization, resulting in a waste of magnetic field utilization. The potential of magnetic gears in transmitting torque is not fully utilized, and the maximum output torque capacity of pseudo-direct drive permanent magnet motors cannot be reached. Summary of the Invention

[0007] In response to the deficiencies and improvement needs of existing technologies, this invention provides a composite magnetic circuit type magnetic gear and a pseudo-direct drive permanent magnet motor. The purpose is to optimize the magnetic circuit design of the concentric magnetic gear, improve the torque transmission capability of the magnetic gear, and increase the maximum output torque of the pseudo-direct drive permanent magnet motor containing the magnetic gear.

[0008] To achieve the above objectives, according to one aspect of the present invention, a composite magnetic circuit type magnetic gear is provided, comprising an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out; air gaps are respectively provided between the inner rotor and the magnetic ring rotor, and between the magnetic ring rotor and the outer stator; at least one of the inner rotor and the outer stator is a magnet array with a composite magnetic circuit. The magnetic steel array with a composite magnetic circuit includes an iron core and a radially magnetized magnetic steel array; the radially magnetized magnetic steel array includes multiple radially magnetized magnetic steels distributed at intervals along the circumference, with adjacent radially magnetized magnetic steels having opposite magnetization directions; the radially magnetized magnetic steel portions are embedded in the iron core, the embedded portions having a multi-sided shape that is symmetrical about the radial direction, and the width of the embedded portions gradually decreases along the embedding direction; the iron core is provided with receiving grooves that match the embedded portions of the radially magnetized magnetic steels.

[0009] Furthermore, the magnetic steel array with a composite magnetic circuit also includes a tangentially magnetized magnetic steel array; the tangentially magnetized magnetic steel array includes multiple tangentially magnetized magnetic steels disposed in the gap between adjacent radially magnetized magnetic steels, and the magnetization directions of adjacent tangentially magnetized magnetic steels are opposite; each tangentially magnetized magnetic steel is attached to the surface of the iron core.

[0010] Furthermore, if the inner rotor adopts a magnetic steel array with a composite magnetic circuit, then the slot opening of the receiving groove in the iron core of the inner rotor is provided with a dovetail-shaped boss structure, and the radially magnetized magnet is provided with a dovetail groove that matches the dovetail-shaped boss structure of the receiving groove opening.

[0011] According to another aspect of the present invention, a pseudo-direct drive permanent magnet motor is provided, comprising an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out; air gaps are respectively provided between the inner rotor and the magnetic ring rotor, and between the magnetic ring rotor and the outer stator; The outer stator includes a stator core, a stator magnet array, and a stator winding; the stator magnet array includes first stator magnets that are radially magnetized and distributed at circumferential intervals, with adjacent first stator magnets having opposite magnetization directions; The inner rotor uses a magnet array with a composite magnetic circuit; the magnet array with a composite magnetic circuit includes an iron core and a radially magnetized magnet array; the radially magnetized magnet array includes multiple radially magnetized magnets distributed at intervals along the circumference, with adjacent radially magnetized magnets having opposite magnetization directions; the radially magnetized magnets are partially embedded in the iron core, and the embedded part has a multi-sided shape that is symmetrical about the radial direction, and the width of the embedded part gradually decreases along the embedding direction; the iron core is provided with a receiving groove that matches the embedded part of the radially magnetized magnet.

[0012] Furthermore, the magnetic steel array with a composite magnetic circuit also includes a tangentially magnetized magnetic steel array; the tangentially magnetized magnetic steel array includes multiple tangentially magnetized magnetic steels disposed in the gap between adjacent radially magnetized magnetic steels, and the magnetization directions of adjacent tangentially magnetized magnetic steels are opposite; each tangentially magnetized magnetic steel is attached to the surface of the iron core.

[0013] Furthermore, in the iron core of the inner rotor, the slot opening of the receiving groove is provided with a dovetail-shaped boss structure, and the radially magnetized magnet is provided with a dovetail groove that matches the dovetail-shaped boss structure of the receiving groove opening.

[0014] Furthermore, the first stator magnet is embedded in the stator core. The embedded part has a multi-faceted shape that is radially symmetrical, and the width of the embedded part gradually decreases along the embedding direction.

[0015] Furthermore, the stator magnet array also includes second stator magnets disposed in the gap between adjacent first stator magnets and tangentially magnetized, with the magnetization directions of adjacent second stator magnets being opposite.

[0016] Furthermore, the number of stator slots S and the number of pole pairs of the stator magnet array... The following relationship exists between them: ; in, n It is a positive integer.

[0017] Furthermore, the stator winding is an integer slot distributed winding, and the pitch of the stator winding is... satisfy: ; in, This represents the number of pole pairs of the magnet array with a composite magnetic circuit in the inner rotor.

[0018] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: (1) The composite magnetic circuit type magnetic gear provided by the present invention has at least one of the inner rotor or outer stator using a magnetic steel array with a composite magnetic circuit. The geometry of the radially magnetized magnet in the magnetic steel array is specially designed. Specifically, the radially magnetized magnet is embedded in the iron core, and the embedded part is a multi-sided shape that is symmetrical about the radial direction. The width of the embedded part gradually decreases along the embedding direction, thereby ensuring that the magnetic lines of force can be fully filled into the iron yoke with the same irregular design. By providing a variety of different magnetic circuits, the magnetic field utilization rate is effectively improved, thereby improving the torque transmission capability of the magnetic gear and the maximum output torque of the pseudo direct drive permanent magnet motor containing this type of magnetic gear.

[0019] (2) In the preferred embodiment of the composite magnetic circuit type magnetic gear provided by the present invention, a tangential magnetic magnet is also provided at the gap between adjacent radially magnetized magnets, and the magnetization directions of adjacent tangential magnetic magnets are opposite. The tangential magnetic magnet and the radially magnetized magnet cooperate to further guide the reasonable distribution of magnetic lines of force in the iron yoke and air gap, and further improve the magnetic field utilization rate.

[0020] (3) In the preferred embodiment of the composite magnetic circuit type magnetic gear provided by the present invention, a dovetail boss is provided at the slot opening of the receiving groove for embedding radially magnetized magnets in the inner rotor core, and a dovetail groove is provided at the corresponding position on the radially magnetized magnets. The two are matched to further improve the mechanical stability of the magnet array.

[0021] (4) The pseudo direct drive permanent magnet motor provided by the present invention contains the composite magnetic circuit type magnetic gear provided by the present invention, and its maximum output torque is effectively improved.

[0022] (5) In the preferred embodiment of the pseudo-direct drive permanent magnet motor provided by the present invention, the number of stator slots S and the number of pole pairs of the stator magnet array are... Between satisfy ( n (As positive integers), this ensures that each tooth pitch corresponds to an integer number of poles, avoiding uneven magnetic field distribution and local saturation, and reducing the harmonic content of the stator magnet's magnetic field.

[0023] (6) In a preferred embodiment of the pseudo-direct drive permanent magnet motor provided by the present invention, the stator winding is an integer slot distributed winding, and the pitch of the stator winding is... satisfy: This ensures that the main magnetomotive force generated by the winding is the same as the number of pole pairs of the inner rotor, reducing the crowding of the magnetic circuit by non-working harmonics in traditional pseudo-direct drive permanent magnet motors, further improving the utilization rate of the magnetic circuit, and reducing the torque attenuation caused by saturation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a conventional magnetic gear.

[0025] Figure 2 This is a schematic diagram of a conventional surface-mount magnet array.

[0026] Figure 3 This is a schematic diagram of the magnetic circuit of a conventional surface-mount magnet array.

[0027] Figure 4 This is a schematic diagram of the magnetic field lines and magnetic density cloud distribution of a conventional magnetic gear.

[0028] Figure 5 This is a schematic diagram of a magnetic steel array with a composite magnetic circuit provided by the present invention.

[0029] Figure 6 for Figure 5 The diagram shows the magnetic circuit layout of a magnet array with a composite magnetic circuit.

[0030] Figure 7 A schematic diagram of another magnetic steel array with a composite magnetic circuit provided by the present invention.

[0031] Figure 8 for Figure 7 The diagram shows the magnetic circuit layout of a magnet array with a composite magnetic circuit.

[0032] Figure 9 This is a schematic diagram of another magnetic steel array with a composite magnetic circuit provided by the present invention.

[0033] Figure 10 for Figure 9 The diagram shows the magnetic circuit layout of a magnet array with a composite magnetic circuit.

[0034] Figure 11 This is a schematic diagram of the structure of the composite magnetic circuit type magnetic gear provided by the present invention.

[0035] Figure 12 for Figure 11 The diagram shows the distribution of magnetic field lines and magnetic density cloud map of the composite magnetic circuit type magnetic gear.

[0036] Figure 13 This is a comparison diagram of the external air gap magnetic flux density waveforms of conventional magnetic gears and composite magnetic circuit type magnetic gears.

[0037] Figure 14 This is a comparison of the output torque waveforms of conventional magnetic gears and composite magnetic circuit type magnetic gears.

[0038] Figure 15 This is a schematic diagram of the pseudo-direct drive permanent magnet motor provided by the present invention.

[0039] Figure 16 This is a schematic diagram of a conventional pseudo-direct drive permanent magnet motor.

[0040] Figure 17 This is a schematic diagram of the magnetic field lines and magnetic density cloud distribution of a conventional pseudo-direct drive permanent magnet motor.

[0041] Figure 18 for Figure 15 The diagram shows the distribution of magnetic field lines and magnetic density cloud map of the pseudo-direct drive permanent magnet motor.

[0042] Figure 19 This is a schematic diagram of another pseudo-direct drive permanent magnet motor provided by the present invention.

[0043] Figure 20 for Figure 19 The diagram shows the distribution of magnetic field lines and magnetic density cloud map of the pseudo-direct drive permanent magnet motor. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0045] In this invention, the terms "first," "second," etc. (if present) in the invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0046] Conventional concentric magnetic gear structures, such as Figure 1 As shown, it includes an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out, with two air gaps separating the three parts. In a conventional concentric magnetic gear, both the inner rotor and the outer stator contain an iron core and a magnet array, with the magnet array in the inner rotor attached to the outer surface of the iron core, and the magnet array in the outer stator attached to the inner surface of the iron core.

[0047] A schematic diagram of a conventional surface-mount magnet array is shown below. Figure 2 As shown, the magnets in the magnet array are radially magnetized, and the magnetization directions of adjacent magnets are opposite, that is, one magnetization direction is radially inward and the other magnetization direction is radially outward. Figure 2 The magnetic circuit of the magnet array shown is as follows Figure 3 As shown, the radial magnetic circuit consists of an air gap, magnets, and an iron yoke connected in series, while the tangential magnetic circuit mainly passes through the iron yoke. The magnetic circuit is relatively simple, resulting in low magnet utilization and wasted magnetic field resources. This fails to fully utilize the torque transmission potential of the magnetic gear. Even when a magnetic gear designed based on this circuit is applied to a pseudo-direct-drive permanent magnet motor, it cannot reach the maximum output torque limit of the pseudo-direct-drive permanent magnet motor. The distribution of magnetic field lines and magnetic density cloud diagrams of a conventional magnetic gear is shown below. Figure 4 As shown.

[0048] To address this problem, the present invention provides a composite magnetic circuit type magnetic gear and a pseudo-direct drive permanent magnet motor. By optimizing the shape and arrangement of the magnet array, the magnetic circuit design is optimized, thereby reducing magnetic leakage, increasing the fundamental amplitude of the air gap magnetic flux density, improving the torque transmission capability of the magnetic gear, and increasing the maximum output torque of the pseudo-direct drive motor containing the magnetic gear.

[0049] The optimized magnetic array diagram and magnetic circuit routing of this invention are as follows: Figures 5-10 As shown. The magnet array provided by this invention is a magnet array with a composite magnetic circuit. This magnet array, through special design of the magnetization direction and geometry of the magnets (such as wedge design of the iron core and magnets), makes its magnetic circuit composed of at least two basic magnetic circuits, thereby greatly improving the magnetic field utilization rate per unit volume. Specifically, the composite magnetic circuit type magnet array provided by this invention further designs the geometry and magnetization direction of the magnet array. In terms of shape, it includes at least radially magnetized magnets with specially designed polygonal bottoms. The part of the magnet that does not face the air gap is designed as a multi-faceted irregular shape and embedded in the iron core to ensure that the magnetic lines of force can be fully filled into the iron yoke, which also has an irregular design. By providing multiple different magnetic circuits, local saturation is greatly avoided. In terms of magnetization direction, this invention further introduces tangentially magnetized magnets into the magnet array with composite magnetic circuits. Compared with traditional surface-mount or Halbach arrays, it provides magnets with multiple magnetization directions to cooperate with each other. Combined with the special geometric design, it can further guide the rational distribution of magnetic lines of force in the iron yoke and air gap.

[0050] Figure 5 The diagram shows a magnetic array with a composite magnetic circuit provided by the present invention. It includes two types of magnets: radially magnetized magnets and tangentially magnetized magnets, arranged alternately. Adjacent radially magnetized magnets have opposite magnetization directions, as do adjacent tangentially magnetized magnets. The shapes of the radially magnetized magnets and tangentially magnetized magnets are different. To optimize the magnetic circuit design, in this embodiment, the portion of the radially magnetized magnet facing away from the air gap is embedded in the core. This embedded portion is a multi-faceted structure symmetrical about the radial direction, and its width gradually decreases in the embedding direction. Correspondingly, the core yoke is designed as an irregularly shaped structure matching the radially magnetized magnets. The magnets are glued together and to the yoke to ensure mechanical reliability. From an axial cross-section, the radially magnetized magnet has an inverted polygonal cross-section, and the tangentially magnetized magnet has a fan-shaped cross-section. The surface shape of the yoke matches the shape of the magnets to fit them. It is easy to understand that, for the inner rotor, the radial magnets are embedded in the radial direction inward, while for the outer stator, the radial magnets are embedded in the radial direction outward.

[0051] Figure 5The magnetic circuit path of the magnet array shown is as follows: Figure 6 As shown, it mainly consists of three types of magnetic circuits: the first consists of a radial magnetic circuit composed of an air gap and radially magnetized magnets, and a tangential magnetic circuit composed of tangentially magnetized magnets; the second consists of a radial magnetic circuit composed of an air gap and radially magnetized magnets, and a tangential magnetic circuit composed of an iron yoke; the third mainly consists of a radial magnetic circuit composed of an air gap, radially magnetized magnets, and an iron yoke, and a tangential magnetic circuit composed of an iron yoke.

[0052] contrast Figure 6 and Figure 3 As can be seen, compared with conventional magnetic steel arrays, the magnetic steel array with composite magnetic circuit provided by this invention improves the utilization rate of permanent magnets in the same volume, optimizes the orientation of magnetic lines of force in the air gap, magnets, and iron core, increases the upper limit of magnetic field utilization, reduces the local saturation of the iron yoke, and promotes a larger fundamental magnetic field. The magnets have an embedded structural design, and the iron core itself forms a dovetail groove structure, which greatly increases the contact area between the magnets and the iron yoke, making the magnets more firmly fixed. This is beneficial to improving the mechanical reliability of the magnetic gear and its composite pseudo-direct drive motor, and improving its high-speed performance. The d-axis and q-axis inductance of the iron core are asymmetrical, thus exhibiting a salient pole effect. For the magnetic gear and pseudo-direct drive motor, this increases the reluctance torque component, which can further improve the torque transmission capability of the magnetic gear and the upper limit of the output torque of the pseudo-direct drive motor.

[0053] Based on the proposed design concept of enriching the magnetic circuit components of the magnet array to improve the magnetic field utilization, there are multiple ways to realize a magnet array with a composite magnetic circuit. Figure 5 The illustrated magnetic array with a composite magnetic circuit includes both radially magnetized magnets and tangentially magnetized magnets. Specifically, the cross-section of the embedded portion of the radially magnetized magnet is an inverted trapezoidal structure with three edges. It should be noted that in this embodiment, the edges connecting the embedded and unembedded portions of the radially magnetized magnet are not on the same straight line. In other implementations, the magnetic array with a composite magnetic circuit may also omit tangentially magnetized magnets and only include radially magnetized magnets, such as... Figure 7 As shown, its magnetic circuit direction is as follows Figure 8 As shown, comparison Figure 8 and Figure 3 It can be seen that, due to the embedded structure design of the radially magnetized magnets, even after eliminating the tangentially magnetized magnets, the magnetic circuit composition is still richer and the magnetic field utilization is improved compared to traditional surface-mount magnet arrays. The shape of the embedded portion of the radially magnetized magnet can also be other multi-faceted shapes that are radially symmetrical and gradually narrow along the embedding direction, such as... Figure 9 The shape shown contains four edges that gradually narrow, and its magnetic circuit direction is as follows: Figure 10 As shown. Depending on the actual needs, the shape of the radially magnetized magnet embedding part can also be designed to have a structure with 5 or more edges. More examples will not be listed here.

[0054] Based on the proposed magnetic steel array with a composite magnetic circuit, the present invention further proposes a composite magnetic circuit type magnetic gear and a pseudo-direct drive permanent magnet motor containing the composite magnetic circuit type magnetic gear. The following are the corresponding embodiments.

[0055] Example 1: A composite magnetic circuit type magnetic gear, the structure of which is as follows: Figure 11 As shown, it includes an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out, wherein both the inner rotor and the outer stator adopt the magnetic steel array with composite magnetic circuit proposed in this invention.

[0056] Specifically, the magnetic steel array with a composite magnetic circuit includes an iron core and a radially magnetized magnetic steel array; the radially magnetized magnetic steel array includes multiple radially magnetized magnetic steels distributed at intervals along the circumference, with adjacent radially magnetized magnetic steels having opposite magnetization directions; the radially magnetized magnetic steel portions are embedded in the iron core, the embedded portions having a multi-sided shape that is radially symmetrical, and the width of the embedded portions gradually decreases along the embedding direction; the iron core is provided with receiving grooves that match the embedded portions of the radially magnetized magnetic steels; the magnetic steel array with a composite magnetic circuit also includes a tangentially magnetized magnetic steel array; the tangentially magnetized magnetic steel array includes multiple tangentially magnetized magnetic steels disposed in the gaps between adjacent radially magnetized magnetic steels, with adjacent tangentially magnetized magnetic steels having opposite magnetization directions; each tangentially magnetized magnetic steel is attached to the surface of the iron core.

[0057] The torque transmission capability of the composite magnetic circuit type magnetic gear proposed in this invention will be analyzed below.

[0058] Without a magnetic adjusting ring, a spatial magnetic field can be generated in the air gap if the magnet array of the inner rotor or outer stator acts alone. Its radial component and tangential components These are respectively represented as Formula Chapter (Next Chapter) Section 1 Formula Chapter (Next Chapter) Section 1: ; In the formula, and These represent the polar radius and polar angle in the air gap polar coordinate system, respectively. This represents the number of pole pairs of the rotor permanent magnet. Indicates the harmonic order. Indicates the rotor speed. Indicates the initial position angle. Indicates time; When there is no adjusting magnetic ring Fourier coefficients of the radial magnetic flux density component of the second harmonic. When there is no adjusting magnetic ring The Fourier coefficients of the subharmonic tangential magnetic flux density components depend on the arrangement of the magnet array.

[0059] After introducing the adjusting ring structure, the magnetic permeability in the air gap will change. The specific permeability is defined as the ratio of the air gap permeability with and without the adjusting ring, and it can be Fourier decomposed as follows: ; In the formula, The Fourier coefficients representing the permeability amplitude at different orders are... Represents the constant term of magnetic permeability. express Secondary magnetic permeability To adjust the number of poles of the magnet block in the magnetic ring. To adjust the mechanical rotation speed of the magnetic ring.

[0060] After the introduction of the magnetic ring rotor, the air gap magnetic field generated by the spatial magnetic field of the inner rotor or outer stator magnet array is modulated by the magnetic ring. It should be: .

[0061] The air gap magnetic field can be obtained by combining the above expressions. radial component and tangential components They are respectively: ; .

[0062] From the formula and From the expression, it can be seen that, regardless of whether the spatial magnetic field generated by the inner rotor magnet or the stator magnet is under the action of the adjusting ring, the number of pole pairs of the newly generated spatially distributed magnetic field harmonics is: ; The rotational speed of the harmonic for: .

[0063] according to As can be seen from the expression, after introducing the adjusting ring, the spatial magnetic field generated by the inner rotor or outer stator magnet array, after being modulated by the adjusting ring, will generate harmonic magnetic fields with different rotational speeds and pole pairs in the air gap opposite each other, and the amplitude of these harmonics depends on the magnetic flux density amplitude of the original magnet array. When another magnet array also generates a magnetic field with the same rotational speed and pole pair number, the two can couple to generate torque.

[0064] To maximize the transmitted torque of the concentric magnetic gears, the spatial magnetic field harmonic with the largest amplitude after modulation by the magnetic ring should be selected as the working harmonic. Since generally, higher harmonic orders result in lower harmonic amplitudes, this is the optimal choice. , At this point, the amplitude of the modulated spatial magnetic field harmonics is at its maximum, that is, when the number of pole pairs of the inner rotor's magnet array is... At that time, the number of pole pairs of the external stator magnet array should be . Generally At this point, the magnetic field on the inner rotor, after modulation, is exactly at the same speed and frequency as the magnetic field generated by the stator magnet array, allowing them to couple and transmit stable torque. Furthermore, it can be seen that the torque transmission capability depends on... and Size.

[0065] Compared to conventional magnetic gears, the composite magnetic circuit type magnetic gear proposed in this invention improves the reuse rate of the magnetic circuit through special design of the geometry of the magnet array and the magnetization direction, thereby generating a larger air gap magnetic flux density in the same volume, which improves... and The size of the magnetic field lines and magnetic density cloud diagram of the composite magnetic circuit type magnetic gear proposed in this invention are shown in the figure below. Figure 12 As shown. With the same outer diameter, and Figure 4 Compared with conventional magnetic gears, the proposed composite magnetic circuit type magnetic gear has a larger working magnetic flux density. Its inner rotor and outer stator both exhibit a composite magnetic circuit composed of multiple magnetic circuits, which allows it to provide a larger air gap magnetic flux density in the same volume, enhances the saturation limit of the magnetic circuit, and further improves the upper limit of torque transmission of the magnetic gear.

[0066] Comparison of the external air gap magnetic flux density waveforms of conventional magnetic gears and the composite magnetic circuit type magnetic gear provided by this invention: Figure 13 As shown, according to Figure 13 The comparison results show that the composite magnetic circuit type magnetic gear proposed in this invention has a larger magnetic flux density harmonic amplitude. The output torque waveforms of the two magnetic gears are shown below. Figure 14 As shown in Table 1, the average torque and torque ripple are also presented. According to the results in Table 1, compared with conventional magnetic gears, the composite magnetic circuit type magnetic gear provided by this invention increases the maximum transmitted torque by 41% and reduces the torque ripple rate by 59%.

[0067] Table 1 Average torque and torque pulsation of the magnetic gear

[0068] In summary, this embodiment optimizes the shape and arrangement of the magnets in the magnet array, enabling both the inner rotor and the outer stator to exhibit a composite magnetic circuit composed of multiple magnetic circuits. As a result, the magnetic gear can provide a larger air gap magnetic flux density within the same volume, enhancing the saturation limit of the magnetic circuit and further improving the upper limit of torque transmission of the magnetic gear.

[0069] It is easy to understand that, in practical applications, the magnetic steel array with composite magnetic circuit proposed in this invention can also be used only on the inner rotor or outer stator side, depending on specific needs.

[0070] As a preferred embodiment, when the inner rotor adopts a magnet array with a composite magnetic circuit, the slot of the receiving groove on the stator of the magnet array for accommodating the embedded part of the radially magnetized magnet is provided with a dovetail boss, and the radially magnetized magnet is provided with a matching dovetail groove, thereby further improving the mechanical stability of the magnet array on the inner rotor side.

[0071] Example 2: A pseudo-direct-drive permanent magnet motor, its structure is as follows: Figure 15 As shown, it includes an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out; air gaps are respectively provided between the inner rotor and the magnetic ring rotor, and between the magnetic ring rotor and the outer stator; The outer stator includes a stator core, a stator magnet array, and a stator winding; the stator magnet array includes first stator magnets that are radially magnetized and distributed at circumferential intervals, with adjacent first stator magnets having opposite magnetization directions; The inner rotor uses a magnet array with a composite magnetic circuit; the magnet array with a composite magnetic circuit includes an iron core and a radially magnetized magnet array; the radially magnetized magnet array includes multiple radially magnetized magnets distributed at intervals along the circumference, with adjacent radially magnetized magnets having opposite magnetization directions; the radially magnetized magnets are partially embedded in the iron core, and the embedded part has a multi-sided shape that is symmetrical about the radial direction, and the width of the embedded part gradually decreases along the embedding direction; the iron core is provided with a receiving groove that matches the embedded part of the radially magnetized magnet.

[0072] The structure of a conventional pseudo-direct drive permanent magnet motor is as follows: Figure 16 As shown, conventional pseudo-direct drive motors use fractional-slot double-layer concentrated windings to drive the inner rotor. They have a relatively small number of slots, and each slot has multiple pairs of pole magnets distributed unevenly, resulting in an uneven magnetic field distribution and localized saturation. For example... Figure 16 As shown, each tooth has 2 or 3 pairs of poles, and the slots correspond to different positions, resulting in a high harmonic content in the stator magnet's magnetic field and an uneven distribution of the stator yoke magnetic flux density. The magnetic field line distribution and magnetic flux density cloud diagram of a conventional pseudo-direct drive motor are shown below. Figure 17 As shown. According to Figure 17 It can be seen that the magnetic field of a conventional pseudo-direct drive permanent magnet motor is significantly uneven. When the right side is saturated, the magnetic field on the left side is concentrated in the tooth section, resulting in wasted space.

[0073] Compared with conventional pseudo-direct-drive permanent magnet motors, the pseudo-direct-drive permanent magnet motor provided in this embodiment is characterized by containing a composite magnetic circuit type magnetic gear. Specifically, the inner rotor adopts a magnet array with a composite magnetic circuit. Similar to the analysis in Embodiment 1 above, the pseudo-direct-drive permanent magnet motor provided in this embodiment has a larger working magnetic flux density because the composite magnetic circuit type magnetic gear uses a magnet array with a composite magnetic circuit. As a result, the inner rotor exhibits a composite magnetic circuit composed of multiple magnetic circuits. This allows it to provide a larger air gap magnetic flux density within the same volume, enhances the saturation limit of the magnetic circuit, and further improves the torque transmission upper limit of the magnetic gear. Correspondingly, the maximum output torque of the pseudo-direct-drive permanent magnet motor containing this composite magnetic circuit type magnetic gear is effectively improved.

[0074] To address the issues of uneven magnetic field distribution and local saturation in conventional pseudo-direct drive permanent magnet motors, this embodiment further optimizes the magnet distribution and winding configuration on the outer stator side of the pseudo-direct drive permanent magnet motor.

[0075] like Figure 15 As shown, in this embodiment, the first stator magnet is embedded in the stator core. The embedded part is a multi-sided shape that is symmetrical about the radial direction, and the width of the embedded part gradually decreases along the embedding direction. Based on this design, the tooth profile is designed as a wedge structure, which can not only better position the magnet during installation, but also provide a more reasonable magnetic circuit structure in terms of electromagnetic characteristics.

[0076] Furthermore, instead of the conventional fractional-slot double-layer concentrated winding, an integer-slot single-layer distributed winding is adopted. The winding pitch is designed according to the number of working harmonic pole pairs of the composite magnetic circuit type magnetic gear, so that the magnetomotive force harmonics of the stator winding are highly matched with the working harmonics of the magnetic gear, thereby improving the magnetic field coupling efficiency.

[0077] This embodiment further optimizes the number of slots located in the stator to improve the utilization rate of the motor's magnetic circuit space. The relevant analysis is as follows: If the stator magnet array uses a pole pair number of Composite magnetic circuit type magnet array, its number of slots Should meet: ; in, The value is a positive integer; by setting the number of stator slots according to the above formula, it can be guaranteed that each tooth pitch corresponds to an integer number of pole pairs, and the number of pole pairs per tooth is... .

[0078] This embodiment uses an integer-slot distributed winding instead of the traditional fractional-slot concentrated winding to further reduce the non-working harmonic content, make greater use of the existing magnetic circuit, accommodate the working magnetic flux density, and reduce unnecessary saturation. Specifically, the integer-slot distributed winding used in this embodiment has a pitch of... satisfy: ; in, denoted as the number of pole pairs in the internal rotor magnet array.

[0079] To satisfy the principle of magnetic field modulation, the number of pole pairs in the inner rotor magnet array and the number of pole pairs in the stator magnet array must satisfy: ; in, To adjust the number of teeth on the magnetic ring rotor.

[0080] Further analysis reveals: .

[0081] Under the above constraints, it can be ensured that the main magnetomotive force generated by the winding is the same as the number of pole pairs of the inner rotor, which reduces the crowding of the magnetic circuit by the non-working harmonics in the traditional pseudo direct drive permanent magnet motor, further improves the utilization rate of the magnetic circuit, and reduces the torque attenuation caused by saturation.

[0082] Optionally, in this embodiment, the number of stator slots is 24, and a pair of magnets are distributed under each tooth, i.e., n=2. In this case, the relationship between the armature span and the number of slots satisfies: ; In this embodiment, take , The number of external stator pole pairs is The number of pole pairs of the inner rotor magnet array At this time, the stator armature uses a single-layer distributed winding with an integer slot pitch of 3.

[0083] The magnetic field line distribution and magnetic density cloud diagram of the pseudo-direct drive permanent magnet motor provided in this embodiment are as follows: Figure 18 As shown, its magnetic field distribution exhibits a uniform characteristic, with no obvious local concentration of magnetic field lines in the stator teeth and yoke, and the magnetic flux density saturation region is significantly reduced, effectively utilizing the space of the stator core. Simultaneously, due to the use of a composite magnetic circuit magnet array in the rotor, the fundamental amplitude of the air gap magnetic flux density is significantly increased. Combined with the optimized stator design, this results in a significant improvement in the motor's magnetic field coupling efficiency.

[0084] In a preferred embodiment, in this embodiment, in the magnet array with a composite magnetic circuit on the inner rotor side, the slot of the receiving groove on the stator for accommodating the embedded part of the radially magnetized magnet is provided with a dovetail boss, and the radially magnetized magnet is provided with a matching dovetail groove, thereby further improving the mechanical stability of the magnet array on the inner rotor side.

[0085] Example 3: A pseudo-direct-drive permanent magnet motor, such as Figure 19As shown, it includes an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out. This embodiment is similar to Embodiment 2 above, except that in this embodiment, the number of stator slots is... Each tooth has a pair of poles, i.e., n=1. In this case, the relationship between the winding span and the number of slots satisfies: ; In this case, take , Stator pole pair number At this time, the stator adopts a single-layer distributed winding with a pitch of 6.

[0086] The magnetic field line distribution and magnetic density cloud diagram of the pseudo-direct drive permanent magnet motor provided in this embodiment are as follows: Figure 20 As shown, its magnetic field exhibits the characteristics of double-end magnetic concentration of the stator and rotor and uniform conduction throughout the entire domain. The strong magnetic field generated by the inner rotor composite magnetic circuit is precisely coupled with the magnetic field generated by the stator composite magnetic circuit after being modulated by the magnetic adjustment ring. The magnetic lines of force form a complete and smooth closed loop between the stator and rotor, the air gap, and the magnetic adjustment ring, without obvious magnetic concentration or magnetic field blank areas.

[0087] In addition, in this embodiment, the stator magnet array also includes a second stator magnet disposed in the gap between adjacent first stator magnets and tangentially magnetized, with the magnetization directions of adjacent second stator magnets being opposite.

[0088] In this embodiment, the stator-side magnet array also includes radially magnetized magnets and tangentially magnetized magnets, realizing a dual composite magnetic circuit. The synergistic effect of the dual composite magnetic circuits increases the fundamental amplitude of the air gap magnetic flux density of the motor by 25%-30% compared to Embodiment 2, and by more than 60% compared to a conventional pseudo-direct drive motor. At the same time, due to the mutual cancellation of harmonics, the torque ripple rate of the motor is further reduced to below 2%, which is far superior to a conventional pseudo-direct drive motor and the pseudo-direct drive permanent magnet motor provided in Embodiment 2.

[0089] The pseudo-direct drive permanent magnet motor provided in this embodiment has achieved further breakthroughs in torque output capability, magnetic field utilization, and operational stability thanks to the structural advantages of the dual composite magnetic circuit. Its maximum output torque is more than 70% higher than that of conventional pseudo-direct drive motors, and its magnet utilization rate is more than 50% higher than that of conventional structures. It is suitable for high-end direct drive fields such as aerospace, oilfield development, and other fields that have stringent requirements for low speed, high torque, and high operational stability.

[0090] Both Embodiment 1 and Embodiment 2 retain the core advantages of the pseudo-direct drive motor: "no mechanical gearbox and high torque at low speed." At the same time, through the design optimization of the composite magnetic circuit, the technical problems of low magnetic field utilization, local magnetic saturation, and high harmonic content of conventional pseudo-direct drive motors are solved. Moreover, the structural compactness is comparable to that of conventional pseudo-direct drive motors, without the need to increase the size of the equipment. They can directly replace the existing "motor + gearbox" electric drive system, significantly reducing the overall size and weight of the electric drive system.

[0091] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite magnetic circuit type magnetic gear, characterized in that, It includes an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out; air gaps are respectively provided between the inner rotor and the magnetic ring rotor, and between the magnetic ring rotor and the outer stator; at least one of the inner rotor and the outer stator adopts a magnetic steel array with a composite magnetic circuit; The magnetic steel array with a composite magnetic circuit includes an iron core and a radially magnetized magnetic steel array; the radially magnetized magnetic steel array includes multiple radially magnetized magnetic steels distributed at intervals along the circumference, with adjacent radially magnetized magnetic steels having opposite magnetization directions; the radially magnetized magnetic steel portions are embedded in the iron core, the embedded portions having a multi-sided shape that is symmetrical about the radial direction, and the width of the embedded portions gradually decreases along the embedding direction; the iron core is provided with receiving grooves that match the embedded portions of the radially magnetized magnetic steels.

2. The composite magnetic circuit type magnetic gear as described in claim 1, characterized in that, The magnetic steel array with a composite magnetic circuit further includes a tangentially magnetized magnetic steel array; the tangentially magnetized magnetic steel array includes a plurality of tangentially magnetized magnetic steels disposed in the gap between adjacent radially magnetized magnetic steels, the magnetization directions of adjacent tangentially magnetized magnetic steels being opposite; each tangentially magnetized magnetic steel is attached to the surface of the iron core.

3. The composite magnetic circuit type magnetic gear as described in claim 1 or 2, characterized in that, The inner rotor uses a magnetic steel array with a composite magnetic circuit. In the iron core of the inner rotor, the slot opening of the receiving groove is provided with a dovetail-shaped boss structure, and the radially magnetized magnet is provided with a dovetail groove that matches the dovetail-shaped boss structure of the receiving groove opening.

4. A pseudo-direct-drive permanent magnet motor, characterized in that, It includes an inner rotor, a magnetic ring rotor, and an outer stator arranged concentrically from the inside out; air gaps are respectively provided between the inner rotor and the magnetic ring rotor, and between the magnetic ring rotor and the outer stator; The outer stator includes a stator core, a stator magnet array, and a stator winding; the stator magnet array includes first stator magnets that are radially magnetized and distributed at circumferential intervals, with adjacent first stator magnets having opposite magnetization directions; The inner rotor employs a magnet array with a composite magnetic circuit; the magnet array with a composite magnetic circuit includes an iron core and a radially magnetized magnet array; the radially magnetized magnet array includes multiple radially magnetized magnets distributed at intervals along the circumference, with adjacent radially magnetized magnets having opposite magnetization directions; the radially magnetized magnets are partially embedded in the iron core, the embedded portion having a multi-sided shape that is radially symmetrical, and the width of the embedded portion gradually decreases along the embedding direction; the iron core is provided with a receiving groove that matches the embedded portion of the radially magnetized magnets.

5. The pseudo-direct-drive permanent magnet motor as described in claim 4, characterized in that, The magnetic steel array with a composite magnetic circuit further includes a tangentially magnetized magnetic steel array; the tangentially magnetized magnetic steel array includes a plurality of tangentially magnetized magnetic steels disposed in the gap between adjacent radially magnetized magnetic steels, the magnetization directions of adjacent tangentially magnetized magnetic steels being opposite; each tangentially magnetized magnetic steel is attached to the surface of the iron core.

6. The pseudo-direct-drive permanent magnet motor as described in claim 4 or 5, characterized in that, In the inner rotor core, the slot opening of the receiving groove is provided with a dovetail-shaped boss structure, and the radial magnet is provided with a dovetail groove that matches the dovetail-shaped boss structure of the receiving groove opening.

7. The pseudo-direct-drive permanent magnet motor as described in claim 4 or 5, characterized in that, The first stator magnet is embedded in the stator core. The embedded part has a multi-faceted shape that is radially symmetrical, and the width of the embedded part gradually decreases along the embedding direction.

8. The pseudo-direct-drive permanent magnet motor as described in claim 4 or 5, characterized in that, The stator magnet array also includes second stator magnets disposed in the gap between adjacent first stator magnets and tangentially magnetized, with the magnetization directions of adjacent second stator magnets being opposite.

9. The pseudo-direct-drive permanent magnet motor as described in claim 4 or 5, characterized in that, The number of stator slots S and the number of pole pairs of the stator magnet array The following relationship exists between them: ； in, n It is a positive integer.

10. The pseudo-direct-drive permanent magnet motor as described in claim 9, characterized in that, The stator winding is an integer slot distribution winding, and the pitch of the stator winding is... satisfy: ； in, This represents the number of pole pairs of the magnet array with a composite magnetic circuit in the inner rotor.

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