Electromagnetic drive based on asymmetric profiled rotor topology

Abstract

The application discloses an electromagnetic drive based on an asymmetric special-shaped rotor topological structure, which comprises a stator and a rotor coaxially nested in sequence from outside to inside; the stator comprises a stator core and a plurality of windings; first and second permanent magnets of the rotor are uniformly and alternately arranged around the outer periphery of the rotor core; two first working surfaces of the first and second permanent magnets respectively extend outward in directions away from each other to enlarge the magnetic flux emission area space of the permanent magnets; a first core is arranged between each adjacent first working surface of the first and second permanent magnets; and a second core is arranged between each adjacent second working surface of the first and second permanent magnets. The rotor core of the self-locking permanent magnet is realized by ferromagnetic rivets to replace the rotor sheath structure and reduce the air gap reluctance; the trapezoidal permanent magnet structure arranged oppositely is adopted to enhance the magnetic aggregation effect and reduce the rotor permanent magnet reluctance. The structure can effectively increase the rotor and air gap permeance, suppress the short-circuit current, and simultaneously improve the system torque and the utilization rate of the permanent magnet.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of driving motor, and particularly to an electromagnetic drive based on an asymmetric profiled rotor topology. BACKGROUND

[0002] In high-performance permanent magnet motor applications, such as electric vehicles and aerospace actuators, improving torque output, permanent magnet utilization and operational reliability are important concerns. Among the possible failures of permanent magnet electromagnetic drives, short circuit failure is the most serious, because the excitation air gap magnetic field generated by the permanent magnet motor is difficult to adjust and weaken, and the short circuit current caused by the back electromotive force will not only cause irreversible demagnetization of the permanent magnet and large torque fluctuation, but also cause overheat, mechanical stress and complete insulation damage.

[0003] Due to the limitations of existing permanent magnet electromagnetic drive structures, it is difficult to simultaneously suppress short circuit current and improve output performance. The most commonly used method is to increase the short circuit inductance of the stator side by using closed slot stator or adding additional slot core, thereby suppressing the short circuit current. However, this will result in large rotor permanent magnet leakage or low stator winding slot fill rate, thereby damaging the output torque of the electromagnetic drive. The remaining means to suppress short circuit current to reduce short circuit failure, such as using low magnetic energy product ferrite permanent magnet or using "single pole" rotor design, can often reduce the back electromotive force under fault conditions to suppress the short circuit current, but inevitably result in a large reduction in electromagnetic drive torque.

[0004] Therefore, how to optimize the electromagnetic drive structure with strong magnetic aggregation to improve the output performance of the permanent magnet motor and ensure its operational reliability is an important technical problem to be solved by those skilled in the art. SUMMARY

[0005] The present application provides an electromagnetic drive based on an asymmetric profiled rotor topology to suppress short circuit current and improve output performance.

[0006] To solve the above technical problems, the present application provides an electromagnetic drive based on an asymmetric profiled rotor topology, comprising a stator and a rotor coaxially nested from outside to inside.

[0007] The stator comprises a stator core and a plurality of stator windings, and each stator winding is uniformly arranged around the stator core.

[0008] The rotor comprises a rotor core, a first permanent magnet, a second permanent magnet, a first core and a second core.

[0009] Each of the first permanent magnets and each of the second permanent magnets are uniformly and alternately arranged around the outer periphery of the rotor core, and the first working surface of the first permanent magnet and the first working surface of the second permanent magnet respectively extend outward in directions away from each other to form a magnetic flux emission space with enlarged magnetic flux emission area.

[0010] The first working surface of each of the first permanent magnets and the first working surface of each of the second permanent magnets are provided with the first core, and the second working surface of each of the first permanent magnets and the second working surface of each of the second permanent magnets are provided with the second core.

[0011] Further, the first permanent magnets and the second permanent magnets are trapezoidal or triangular.

[0012] Further, each of the first cores and each of the second cores are provided with a fixing hole, and each of the first cores and each of the second cores are fixed by the ferromagnetic rivets through the fixing holes.

[0013] Further, the material of the ferromagnetic rivets is 2Cr13.

[0014] Further, the first core and the second core are provided with an arc-shaped protrusion.

[0015] The thickness of the arc-shaped protrusion is 0.5mm.

[0016] Further, the stator is a single-layer fractional-slot concentrated winding structure.

[0017] Further, the number of the first permanent magnets and the number of the second permanent magnets are both 8.

[0018] Further, the stator core comprises a plurality of stator slots.

[0019] The stator slots are closed structures, and each of the stator slots is uniformly and alternately arranged in the stator core.

[0020] Further, the stator winding is a three-phase winding or a five-phase winding.

[0021] Further, the stator winding comprises a clockwise arranged A-phase positive electrode winding, a B-phase first negative electrode winding, a B-phase second negative electrode winding, a C-phase positive electrode winding, an A-phase first negative electrode winding, an A-phase second negative electrode winding, a B-phase positive electrode winding, a C-phase first negative electrode winding and a C-phase second negative electrode winding.

[0022] Compared with the prior art, the beneficial effects of the embodiment of the present application are at least one of the following:

[0023] (1) The relative setting trapezoidal permanent magnet structure increases the magnetic flux emission area and reduces the rotor permanent magnet reluctance, and increases the rotor equivalent permeance; the arc-shaped protruding ferromagnetic material of the rotor can further reduce the rotor and air gap equivalent reluctance, and further increase the rotor equivalent permeance; the increased magnetic flux emission area can enhance the air gap magnetic field strength and the output torque of the electromagnetic drive, and the increased rotor side equivalent permeance can effectively improve the stator short-circuit inductance to further suppress the short-circuit current.

[0024] (2) The first and second permanent magnets are placed asymmetrically relative to the pole axis to reduce the high-order harmonic of the air gap magnetic field and the torque ripple. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The structure schematic diagram of the electromagnetic drive based on the asymmetric profile rotor topology structure provided by the embodiment of the application is shown in the figure.

[0026] Figure 2 The comparative schematic diagram of the electromagnetic drive based on the asymmetric profile rotor topology structure and the traditional electromagnetic drive provided by the embodiment of the application is shown in the figure.

[0027] Figure 3 The rotor partial structure schematic diagram of the electromagnetic drive based on the asymmetric profile rotor topology structure provided by the embodiment of the application is shown in the figure.

[0028] Figure 4 The short-circuit current model schematic diagram of the electromagnetic drive based on the asymmetric profile rotor topology structure provided by the embodiment of the application is shown in the figure.

[0029] Figure 5 The schematic diagram of the rotor of the electromagnetic drive based on the asymmetric profile rotor topology structure provided by the embodiment of the application when the rotor is located at the maximum and minimum magnetic permeance positions is shown in the figure.

[0030] Figure 6 The curve diagram of the first iron core inter-turn short-circuit inductance of the electromagnetic drive based on the asymmetric profile rotor topology structure provided by the embodiment of the application with the span angle change is shown in the figure.

[0031] Figure 7 The magnetic flux distribution comparative schematic diagram of the electromagnetic drive based on the asymmetric profile rotor topology structure and two kinds of traditional electromagnetic drives provided by the embodiment of the application is shown in the figure.

[0032] Figure 8 The magnetic flux density waveform comparative schematic diagram of the electromagnetic drive based on the asymmetric profile rotor topology structure and two kinds of traditional electromagnetic drives provided by the embodiment of the application is shown in the figure.

[0033] Figure 9 The counter electromotive force waveform and Fourier waveform comparative results of the electromagnetic drive based on the asymmetric profile rotor topology structure and two kinds of traditional electromagnetic drives provided by the embodiment of the application are shown in the figure.

[0034] Figure 10 A comparison curve of torque waveforms between an electromagnetic drive based on an asymmetric irregular rotor topology and two conventional electromagnetic drives provided for embodiments of the present invention;

[0035] Figure 11 A schematic diagram comparing the fault turn self-inductance of an electromagnetic drive based on an asymmetric irregular rotor topology with two traditional electromagnetic drives, provided for an embodiment of the present invention.

[0036] Figure 12 A schematic diagram comparing the end short-circuit currents of an electromagnetic drive based on an asymmetric irregular rotor topology with two traditional electromagnetic drives, provided for an embodiment of the present invention.

[0037] Figure 13 A schematic diagram comparing the inter-turn short-circuit waveforms of an electromagnetic drive based on an asymmetric irregular rotor topology and two traditional electromagnetic drives, provided for an embodiment of the present invention.

[0038] Reference numerals in the attached drawings: 1. Stator; 2. Rotor; 3. First iron core; 4. Second iron core; 5. First permanent magnet; 6. Stator slot; 7. Second permanent magnet; 8. First working surface; 9. Second working surface. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0041] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0042] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0043] Electromagnetic drives, also known as permanent magnet motors, comprising rotors, stators, and corresponding electromagnetic control systems, are key components of modern electric drive systems. With the development of high-energy-product rare-earth permanent magnets, permanent magnet motors, due to their high efficiency, high power density, and good speed regulation performance, have been widely used in various fields such as industrial automation, electric vehicles, and aerospace. However, in practical applications, permanent magnet motors also face some technical challenges, particularly in reducing short-circuit current, increasing torque, and improving the utilization rate of permanent magnets.

[0044] Short-circuit current is one of the key issues that needs to be monitored during the operation of permanent magnet motors. When a short-circuit fault occurs in the motor, the short-circuit current will increase rapidly, which can not only damage the internal electrical components of the motor, but may also impact the entire power system.

[0045] On the other hand, increasing torque and permanent magnet utilization are also key to improving the performance of permanent magnet motors and reducing manufacturing costs. The magnitude of torque directly affects the motor's load capacity and operating efficiency, while the permanent magnet utilization rate, i.e., the motor's output torque per unit volume of permanent magnet, directly determines the manufacturing cost of high-performance motors. Maintaining motor size and weight while minimizing the use of expensive rare-earth permanent magnets, maximizing motor torque through optimized motor design and improved material properties is a crucial direction for permanent magnet motor research and development.

[0046] However, for rare earth permanent magnet motors, the strong air gap magnetic field and output torque often result in a large short-circuit electromotive force and short-circuit current, making it difficult to achieve a small short-circuit current and a large permanent magnet utilization rate under high torque output. Therefore, how to achieve a balance among these three factors is a challenge in the research and development of high-performance permanent magnet motors.

[0047] One embodiment of the present invention provides an electromagnetic drive based on an asymmetric irregular rotor topology. For details, please refer to [link / reference]. Figure 1 and Figure 3 , Figure 1 The diagram shown is a schematic representation of an electromagnetic drive based on an asymmetric irregular rotor topology, according to one embodiment of the present invention. Figure 3 The diagram shows a partial rotor structure of an electromagnetic drive based on an asymmetric irregular rotor topology provided in an embodiment of the present invention, including a stator and a rotor coaxially nested from the outside to the inside.

[0048] The outer stator employs a single-layer 18s / 16p fractional-slot concentrated winding structure. 18s and 16p represent the number of slots and poles, respectively. Fractional slots are a concept distinct from integer-slot motor windings. Fractional-slot concentrated windings offer advantages such as simple winding structure, low copper usage at the ends, and high winding inductance, and are frequently used in the development of permanent magnet fault-tolerant motors. In this winding structure, the windings in each slot are centrally arranged, and the number of slots per pole per phase is generally a fraction, rather than being distributed across multiple slots as in integer-slot distributed windings, where the number of slots per pole per phase is generally an integer.

[0049] The stator includes a stator core, which is fixed inside the outer casing. Specifically, in this embodiment, the stator core has 18 stator slots, which are evenly arranged around the stator core. To fully utilize the inductance at the stator slot openings to suppress short-circuit current, the stator slots adopt a closed structure. To prevent large rotor leakage flux from the closed slots, the closed slots are stepped.

[0050] Specifically, in this embodiment, the stator winding adopts a three-phase winding, such as... Figure 1 As shown, the stator winding includes phase A winding, phase B winding, and phase C winding, specifically arranged clockwise as phase A positive winding, phase B first negative winding, phase B second negative winding, phase C positive winding, phase A first negative winding, phase A second negative winding, phase B positive winding, phase C first negative winding, and phase C second negative winding.

[0051] In this embodiment, the sinusoidal voltages input to the three-phase windings are 120 electrical degrees out of phase and their frequency is the same as the motor speed, thus forming a rotating armature magnetic field. This armature magnetic field interacts with the rotor magnetic field to generate output torque. Furthermore, the motor ensures reliable operation of the rotor system even when an inter-turn short-circuit fault occurs in one phase winding; and when a short circuit occurs at the end of one phase, it also has a smaller end short-circuit current compared to a typical surface-mounted tile permanent magnet rotor motor.

[0052] It should be noted that the three-phase winding described in this embodiment is only an example. In actual applications, those skilled in the art can choose other options such as five-phase or six-phase windings according to the actual system accuracy requirements and cost constraints based on the scheme described in this application. These options will not be elaborated here.

[0053] Inside the stator is the permanent magnet driven rotor section as described in this embodiment. The rotor includes a rotor core, a first permanent magnet, a second permanent magnet, a first core, and a second core.

[0054] Specifically, such as Figure 1 and Figure 3 As shown, each first permanent magnet and each second permanent magnet are uniformly and alternately arranged in a ring around the outer periphery of the rotor core. The first working surface of the first permanent magnet and the first working surface of the second permanent magnet extend outward in a direction away from each other to form a magnetic flux emission space that amplifies the magnetic flux emission area. The first and second permanent magnets are placed asymmetrically relative to the polar axis to reduce the high-order harmonics of the air gap magnetic field.

[0055] Under normal conditions, both the first and second permanent magnets are trapezoidal permanent magnets, characterized by being narrow at the top and wide at the bottom. Each pair of first and second permanent magnets facing each other on their first working surfaces can be considered as two reluctances connected in parallel radially. The reduced magnet volume and equivalent parallel reluctance both contribute to improving the permeability of the rotor pole array, thus fully utilizing the traditionally neglected contribution of the rotor to the winding inductance. Therefore, in an extremely ideal state, when the upper base of the trapezoidal magnet is sufficiently short, it forms a triangular magnet, possessing the maximum rotor inductance. Considering practical realities, this embodiment uses a trapezoidal permanent magnet as an example for detailed discussion.

[0056] In this embodiment, the trapezoidal permanent magnet uses 8 first permanent magnets and 8 second permanent magnets. The trapezoidal permanent magnet itself is a right-angled trapezoid that is asymmetrical relative to the polar axis. The upper and lower bases of the trapezoidal permanent magnet are respectively attached to the outer and inner circular edges.

[0057] A first iron core is provided between each adjacent first working surface of the first and second permanent magnets, and a second iron core is provided between each adjacent second working surface of the first and second permanent magnets. The first and second iron cores are used to fill the space between each first and second permanent magnet in the rotor and to fix the first and second permanent magnets. Figure 3 As shown, Figure 3 The electromagnetic drive structure of this embodiment is partially shown, with the inner and outer rings laid flat. It can be seen that the first iron core of this embodiment has a triangular shape and an additional 0.5mm thick protrusion after being unfolded in the plane. Therefore, the first iron core in the electromagnetic drive is a fan-shaped structure containing a fan shape and a protrusion around the fan shape. The second iron core of this embodiment has a rectangular shape and an additional 0.5mm thick protrusion after being unfolded in the plane. Therefore, the second iron core in the electromagnetic drive is a fan-ring-like structure containing a fan ring and a protrusion around the fan ring.

[0058] That is, in this embodiment, the first iron core located between each adjacent first working surface of the first permanent magnet and the second permanent magnet is fan-shaped. The second iron core located between each adjacent second working surface of the first permanent magnet and the second permanent magnet is fan-shaped annular.

[0059] In traditional permanent magnet drives, a rotor sheath is typically installed around the rotor to secure the permanent magnets and other materials within it, counteracting the centrifugal force exerted during operation and ensuring reliable rotor operation. In this embodiment, to reduce air gap reluctance and increase air gap permeability, the rotor sheath is omitted. Simultaneously, to secure the permanent magnets, fixing holes are provided on the first and second iron cores. Ferromagnetic 2Cr13 rivets are used to fix the first and second iron cores through these holes. Due to their trapezoidal / triangular structure (narrower on the outside, wider on the inside), the first and second permanent magnets are locked within the rotor by these iron cores. During high-speed centrifugal operation, the first and second iron cores, secured by the 2Cr13 rivets, apply static pressure to the first and second permanent magnets to counteract the centrifugal force exerted on them by the rotor during rotation, ensuring the rotor remains under pressure even at high speeds.

[0060] This fixing method replaces the original method of fixing the rotor with a rotor sheath. The first iron core is set in a fan-shaped form, and the second iron core is designed as a fan-shaped annular form, so the overall outer circumference of the rotor is circular. Specifically, in this embodiment, the protruding parts around the first and second iron cores are designed to have the same thickness as the original rotor sheath, about 0.5 mm, which can further reduce the air gap magnetic resistance.

[0061] In addition, the outer protrusions of the first and second iron cores and the reduced air gap magnetic reluctance can suppress rotor leakage magnetic flux caused by the closed slot stator to a certain extent. Therefore, the rotor torque can be significantly reduced while utilizing the slot leakage inductance. Thus, this fixing method can achieve high inter-turn inductance and low short-circuit current without significantly sacrificing torque output.

[0062] The following uses the electromagnetic drive provided in this embodiment as an example to qualitatively explain why the electromagnetic drive in this embodiment can suppress short-circuit current and ensure operational safety while increasing torque output:

[0063] First, the electromagnetic drive provided in this embodiment can increase the magnetic permeability of the equivalent air gap. The specific reason is that the equivalent air gap magnetic reluctance along the armature flux path is mainly determined by the proportion of ferromagnetic material on the rotor surface closest to the air gap. Therefore, the large-span angle fan-shaped first iron core and fan-shaped annular second iron core used in this embodiment reduce the length of the equivalent air gap and increase the cross-sectional area of ​​the air gap magnetic reluctance.

[0064] Secondly, the electromagnetic drive provided in this embodiment can improve the magnetic permeability of the rotor magnet. Specifically, this is because: ① In this embodiment, almost half of the low-permeability rare-earth permanent magnets present in traditional surface-mount permanent magnet (SPM) motors are replaced by a fan-shaped first iron core and a fan-shaped annular second iron core; ② The trapezoidal first and second permanent magnets used in this embodiment both have a narrow top and wide bottom, and can be considered as two reluctances connected in parallel radially, such as... Figure 2 As shown, Figure 2 This is a schematic diagram comparing electromagnetic drive based on an asymmetric irregular rotor topology with traditional electromagnetic drive, provided by an embodiment of the present invention. Figure 2 (a) is a traditional electromagnetic drive structure. Figure 2 (b) The electromagnetic drive structure provided in this embodiment. Under the electromagnetic drive structure design provided in this embodiment, the reduced magnet volume and equivalent parallel magnetic reluctance help to improve the magnetic permeability of the rotor magnetic pole array, thereby achieving a larger winding inductance. Therefore, under ideal conditions, when the upper base of the trapezoidal magnet is short enough, the trapezoidal magnet approaches the triangular magnet, which helps to achieve the maximum rotor inductance.

[0065] In addition to improving the system's magnetic permeability and short-circuit inductance, the magnetic focusing effect of electromagnetic drive is also enhanced. The specific reasons are as follows: ① The rotor magnetic reluctance can be effectively reduced through the above two aspects; ② Due to the increased emission area of ​​the first working surface of the first permanent magnet and the second permanent magnet used for emitting magnetic flux, and the adoption of tangential magnetization, two relatively arranged trapezoidal magnets replace the single traditional alternating pole permanent magnet, which helps to concentrate the magnetic flux into the air gap and obtain a larger air gap magnetic flux for generating output torque; ③ The first and second iron cores of the rotor are both fixed by ferromagnetic 2cr13 rivets, so the trapezoidal first and second permanent magnets can be locked by these rotor irregular iron cores, thereby eliminating the rotor sheath present in the traditional rotor design. In this case, the outer arc-shaped protrusion of these rotor first and second iron cores can be designed to be the same thickness as the original rotor sheath, specifically, about 0.5 mm in this embodiment, which can further reduce the air gap magnetic reluctance.

[0066] Furthermore, this embodiment quantitatively analyzes the above effects by analyzing the inter-turn short-circuit current and inductance of the electromagnetic drive: such as Figure 4 As shown, Figure 4 This is a schematic diagram of the short-circuit current mathematical model of electromagnetic drive based on an asymmetric irregular rotor topology provided in an embodiment of the present invention. Figure 4 The inter-turn short-circuit current of the permanent magnet driven structure can be modeled as follows:

[0067]

[0068] Among them, I s E2 is the inter-turn short-circuit current, E2 is the back electromotive force of the short-circuit turn, R2 is the resistance of the short-circuit turn, and L is the short-circuit current. s M is the self-inductance of the faulty turn, M is the mutual inductance of the faulty turn, and Λ is the mutual inductance of the faulty turn. rotor For electromagnetically driven rotor permeability, ψ s I is the leakage flux through the slot, and I is the flux flowing through N. s The current of a short-circuit turn.

[0069] The above formula shows that increasing the number of faulty turns increases the self-inductance L. s This is the main way to suppress short-circuit current, while the winding self-inductance is mainly determined by the rotor magnetic permeability Λ. rotor and stator leakage flux ψ s The decision was made. Traditional methods for suppressing short-circuit current mainly focus on increasing the leakage flux linkage ψ by modifying the stator slot shape. s However, the rotor magnetic permeability Λ was ignored. rotor The improvement is significant. In contrast, the electromagnetically driven rotor design of this embodiment can be improved by increasing the equivalent magnetic permeability Λ in the air gap. a And improve the magnetic permeability Λ of the magnet m This effectively increases the rotor's magnetic permeability.

[0070] Among them, the slot leakage flux ψs for:

[0071]

[0072] Among them, such as Figure 5 As shown, Figure 5 This is a schematic diagram of an electromagnetically driven rotor based on an asymmetric irregular rotor topology, showing the rotor at its maximum and minimum permeability positions according to an embodiment of the present invention. μ0 is the free permeability, g is the air gap length, and I... e This refers to the effective axial length of the motor.

[0073] Specifically, in this embodiment, the electromagnetically driven rotor features an alternating arrangement of iron core and permanent magnets. Armature magnet paths connect different parts of the rotor, resulting in a varying rotor permeability Λ. rotor , Figure 5 This shows when the rotor magnetic permeability Λ rotor The relative positions of the rotor and stator when the maximum and minimum values ​​are reached, with the maximum value being... It can be represented as:

[0074]

[0075] Among them, R m Let θ be the outer radius of the trapezoidal permanent magnet. sp This is the stator slot pitch angle.

[0076] In contrast, the rotor magnetic permeability of a conventional sPM rotor motor for:

[0077]

[0078] Among them, h m The thickness of the permanent magnet in the SPM motor.

[0079] Obviously, the maximum rotor permeability of the electromagnetic drive provided in this embodiment is much higher than that of a conventional SPM rotor, because h m +g>g, where h m It is typically 4 to 6 times larger than the air gap length g.

[0080] Furthermore, the minimum rotor magnetic permeability of the electromagnetic drive in this embodiment It is also larger than that of a traditional SPM rotor. This is achieved by increasing the angle of the second iron core, which is shaped like a fan ring, and the angle θ of the first iron core, which is shaped like a fan. t This was achieved. The former reduced the equivalent air gap magnetic reluctance, thereby increasing the air gap magnetic permeability Λ. a The latter reduces the permanent magnet reluctance, thereby increasing the rotor magnet permeability Λ. m Specifically, the minimum rotor magnetic flux connecting the short-circuited turns is now... Figure 5The location shown in (b) can be modeled as follows:

[0081]

[0082] in, θ p Let θ be the polar distance angle. i θ is the rotor asymmetry angle. b and θ t These are the span angles of the second core and the first core, respectively.

[0083] like Figure 6 As shown, Figure 6 The diagram shows the curve of the inter-turn short-circuit inductance of a fan-shaped iron core based on an asymmetric irregular rotor topology, provided in an embodiment of the present invention, as a function of the span angle. Figure 6 This indicates a larger θ t It does indeed help to increase Λ at the same time m and Λ a This achieves a higher short-circuit inductance L s In other words, the electromagnetically driven rotor in this embodiment operates at a large span angle θ. t In this case, the air gap permeability and magnet permeability can be increased.

[0084] Therefore, under the same conditions, the span angle θ of the first iron core should be increased as much as possible. t To maximize the short-circuit inductance L s And reduce short-circuit current I s When there is no magnetic material near the air gap on the rotor surface, Λ a It will reach its maximum value. If θ m =0, then the maximum value Λ can be reached. m .

[0085] Furthermore, to demonstrate the advantages of the electromagnetic drive structure in this embodiment, the electromagnetic drive (AICP) in this embodiment was compared with two other conventional electromagnetic drives in various aspects. The other two conventional electromagnetic drives are a typical parallel magnetized surface-mounted tile-shaped permanent magnet rotor (PMR) and a conventional consequent-pole rotor (CPR). To improve the accuracy of the results, the stator geometry, winding configuration, input current, mechanical air gap length, and rotational speed of the three electromagnetic drives remained unchanged. The conventional rotor was set to maximize the amount of permanent magnets used to achieve the optimal torque. The comparison of the operating results is as follows:

[0086] 1) such as Figure 7 As shown, Figure 7The diagram illustrates a comparison of magnetic flux distribution between the electromagnetic drive based on an asymmetric rotor topology provided in this embodiment of the invention and two conventional electromagnetic drives. As can be seen from the diagram, the AICP-LTCS electromagnetic drive of this embodiment exhibits the strongest magnetic field and magnetic isolation characteristics, thus contributing to both high output performance and better fault tolerance.

[0087] 2) such as Figure 8 As shown, Figure 8 This diagram illustrates a comparison of the magnetic flux density waveforms of an electromagnetic drive based on an asymmetric irregular rotor topology, provided in an embodiment of the present invention, and two conventional electromagnetic drives. Figure 8 As shown in (a), the CPR design exhibits an unbalanced air gap flux density distribution, which typically leads to large torque pulsations, unbalanced magnetic forces, and vibrations. In contrast, the AICP rotor of this embodiment effectively mitigates unbalanced air gap magnetic fields and even harmonics, such as Figure 8 As shown in (b). In fact, by setting θ... m =θ i =0 can effectively suppress unbalanced air gap magnetic fields. Furthermore, in this embodiment, the electromagnetically driven air gap magnetic flux density has the highest fundamental amplitude and the highest amplitude for higher-order magnetic harmonics (such as 3D magnetic flux density). rd and 5 th The smaller size of the component helps to achieve a strong and smooth torque output.

[0088] 3) such as Figure 9 As shown, Figure 9 The diagram shows a comparison of the back electromotive force waveform and Fourier waveform of the electromagnetic drive based on the asymmetric non-circular rotor topology provided in the embodiment of the present invention with two conventional electromagnetic drives. Figure 9 The back electromotive force (EMF) waveforms and harmonic content distributions of the three rotors are displayed. The comparison results show that the electromagnetic drive in this embodiment has the highest fundamental amplitude, which helps to improve the average torque output. In contrast, due to the air gap magnetic field imbalance, the CPR has the lowest fundamental amplitude and a larger even-order harmonic content. Although the CPR's lowest back EMF can reduce short-circuit current, it also leads to a significant decrease in torque output. A large torque reduction is generally unacceptable, especially for high-performance electromagnetic drive applications.

[0089] 4) such as Figure 10 As shown, Figure 10 The diagram shows a comparison of torque output performance between the electromagnetic drive based on an asymmetric non-circular rotor topology provided in this embodiment of the invention and two conventional electromagnetic drives. Utilization rate is defined as the ratio of average torque to PM volume. Figure 10The results show that, compared with conventional CPR machines, the proposed AICP electromagnetic drive improves the average torque and permanent magnet utilization rate by 33.7% and 45.1%, respectively. Furthermore, compared with the industrially common PMR design, the AICP design achieves a 67.8% improvement in PM utilization rate, from 0.115 Nm / cm². 3 Up to 0.193 Nm / cm 3 .

[0090] 5) such as Figure 11 As shown, Figure 11 The diagram illustrates a comparison of the self-inductance of fault turns in an electromagnetic drive based on an asymmetric rotor topology provided in an embodiment of the present invention with two conventional electromagnetic drives. All three rotor designs employ the same single-layer 18s / 16p fractional-slot concentrated winding to achieve good physical and electromagnetic isolation performance. Furthermore, the mutual inductance of the fractional-slot concentrated winding configuration is negligible. Therefore, the self-inductance of the short-circuit turn is the primary component and determines the magnitude of the short-circuit current. Figure 11 The self-inductance of the short-circuit turns for three rotor designs is shown. Due to the specific combination of fan-shaped toroidal / fan-shaped first / second iron cores and trapezoidal first / second permanent magnets in the electromagnetically driven rotor of this embodiment, the minimum short-circuit inductance of the AICP design is also greater than the maximum short-circuit inductance of the PMR design. Although the CPR design has the highest maximum short-circuit inductance, its minimum inductance and average torque are poorer. Furthermore, the average short-circuit inductance of the AICP rotor is the highest among these designs, which contributes to achieving a lower short-circuit current.

[0091] 6) such as Figure 12 As shown, Figure 12 The diagram shows a comparison of the end short-circuit currents of an electromagnetic drive based on an asymmetric rotor topology provided in an embodiment of the present invention with two conventional electromagnetic drives. Figure 12 As can be seen, the short-circuit current of the AICP design provided in this embodiment is reduced by 26.7% compared to a typical PMR design. Furthermore, the rated peak current of this electromagnetic drive is 3A, meaning that the short-circuit current of the proposed AICP design only increases by 46.7% compared to the healthy state. In contrast, the short-circuit current of the PMR design is twice the healthy current. Figures 8-10 As shown, thanks to the extremely low back EMF of CPR and the output torque that is difficult to meet performance requirements, its short-circuit current is low.

[0092] 7) such as Figure 13 As shown, Figure 13 The diagram shows a comparison of the inter-turn short-circuit waveforms of an electromagnetic drive based on an asymmetric rotor topology provided in an embodiment of the present invention with two conventional electromagnetic drives. Figure 13It can be seen that under inter-turn fault conditions, the peak current of the AICP design is 11.6% lower than that of a typical PMR design. This is attributed to the larger self-inductance of the AICP mechanism, such as... Figure 11 As shown. Although the short-circuit current of the CPR design is relatively low among these rotor designs, it also suffers a significant torque reduction of approximately one-quarter or 25% compared to the AICP design due to its poor flux focusing effect. These comparisons demonstrate that the AICP design can achieve high torque output and better balance the trade-off between strong magnetic loads (i.e., high back EMF) and high torque and low short-circuit current.

[0093] The advantages of the electromagnetic drive based on the asymmetric irregular rotor topology of this invention are:

[0094] Compared to traditional surface-mount permanent magnet (SPM) motors, in this embodiment, almost half of the low-permeability magnets are replaced by a fan-shaped first iron core and a fan-shaped annular second iron core. The trapezoidal first and second permanent magnets are narrow at the top and wide at the bottom, and can be regarded as two magnetic reluctances connected in parallel along the radial direction. Under the electromagnetic drive structure design provided in this embodiment, the reduced magnet volume and equivalent parallel magnetic reluctance help to improve the permeability of the rotor magnetic pole array, thereby achieving a large winding short-circuit inductance.

[0095] In addition to improving the system's magnetic permeability and short-circuit inductance, the electromagnetic drive's magnetic concentration effect is also enhanced because the rotor reluctance can be effectively reduced through the above two aspects. Furthermore, due to the increased emission area of ​​the first working surface of the first and second permanent magnets used for emitting magnetic flux, and the adoption of tangential magnetization, two relatively arranged trapezoidal magnets replace a single traditional alternating pole permanent magnet, which helps to concentrate the magnetic flux into the air gap and obtain a larger air gap magnetic flux. The first and second iron cores of the rotor are both fixed by ferromagnetic 2Cr13 rivets, so the trapezoidal first and second permanent magnets can be locked by these irregularly shaped rotor cores, thereby eliminating the rotor sheath present in the traditional rotor design. In this case, the outer arc-shaped protrusions of these first and second iron cores of the rotor can be designed to have the same thickness as the original rotor sheath, specifically, about 0.5 mm in this embodiment, which can further reduce the air gap magnetic reluctance.

[0096] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An electromagnetic drive based on an asymmetric irregular rotor topology, characterized in that, It includes a stator and a rotor that are coaxially nested from the outside in; The stator includes a stator core and a plurality of stator windings, each of the stator windings being evenly arranged in a ring within the stator core; The rotor includes a rotor core, a first permanent magnet, a second permanent magnet, a first iron core, and a second iron core; Each of the first permanent magnets and each of the second permanent magnets are uniformly and alternately arranged in a ring around the outer periphery of the rotor core. The first working surface of the first permanent magnet and the first working surface of the second permanent magnet extend outward in a direction away from each other to form a magnetic flux emission space that amplifies the magnetic flux emission area. The first iron core is provided between each adjacent first working surface of the first permanent magnet and the second permanent magnet, and the second iron core is provided between each adjacent second working surface of the first permanent magnet and the second permanent magnet; The first permanent magnet and the second permanent magnet are trapezoidal in shape, and the first permanent magnet and the second permanent magnet are placed asymmetrically with respect to the polar axis; The first iron core and the second iron core are provided with arc-shaped protrusions, the thickness of which is 0.5mm. The protrusions on the periphery of the first iron core and the second iron core are designed to have the same thickness as the original rotor sheath. When the inner ring and the outer ring are laid flat, the first iron core is a triangle with an additional 0.5mm thick protrusion after being unfolded in a plane, and the second iron core is a rectangle with an additional 0.5mm thick protrusion after being unfolded in a plane.

2. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 1, characterized in that, Each of the first iron cores and each of the second iron cores is provided with a fixing hole, and each of the first iron cores and each of the second iron cores is fixed by ferromagnetic rivets through the fixing holes.

3. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 2, characterized in that, The ferromagnetic rivet is made of 2Cr13.

4. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 1, characterized in that, The stator is a single-layer fractional-slot concentrated winding structure.

5. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 1, characterized in that, The number of the first permanent magnet and the second permanent magnet is 8 each.

6. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 1, characterized in that, The stator core includes a plurality of stator slots; The stator slots are closed structures, and each stator slot is evenly arranged in a ring within the stator core.

7. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 1, characterized in that, The stator winding is a three-phase winding or a five-phase winding.

8. The electromagnetic drive based on an asymmetric irregular rotor topology as described in claim 7, characterized in that, The stator windings include a clockwise arrangement of the A-phase positive winding, the B-phase first negative winding, the B-phase second negative winding, the C-phase positive winding, the A-phase first negative winding, the A-phase second negative winding, the B-phase positive winding, the C-phase first negative winding, and the C-phase second negative winding.

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