A stator structure for a single-pole electric machine

Abstract

The application discloses a stator structure of a single magnetic pole motor, comprising a stator assembly and a rotor assembly. The stator assembly comprises a stator core, a plurality of stator core salient poles and windings, and a stator core pole shoe; the rotor assembly comprises magnetic steels uniformly arranged along the circumference of a magnetic conducting ring, and the magnetic poles of all the magnetic steels on the side of the stator assembly are consistent in polarity. The salient poles and windings of the stator core are deflected from the symmetric center point of the end of the stator core pole shoe along the circumference to form a deflection angle, so that the electromagnetic field generated by the energization of the windings has a magnetic field component in the tangential direction of the circumference. While retaining the advantages of low eddy current loss and inhibition of demagnetization of the single magnetic pole motor, the application can increase the force acting on the rotor in the rotation direction, reduce the cogging torque, and improve the comprehensive performance of the motor without increasing the mass and cost of the magnetic steels.

Description

Technical Field

[0001] This application relates to the field of brushless DC motor technology, and more specifically to a stator structure for a single-pole motor. Background Technology

[0002] A brushless DC motor mainly consists of a rotor, a stator, and accessories. The rotor uses permanent magnet materials to form a permanent magnetic field, and the stator forms an electromagnetic induction magnetic field through the windings. The controller electronically commutates and outputs alternating phase electricity, which causes the stator to generate a rotating magnetic field to drive the rotor to rotate, thus realizing the conversion of electrical energy into mechanical energy.

[0003] Conventional permanent magnet brushless motors typically use conductive permanent magnet materials such as neodymium iron boron (NdFeB) as rotor magnets. During motor operation, the alternating rotating magnetic field of the stator and the magnetic field of the rotor superimpose, generating eddy current induction in the rotor magnets and causing heat generation. Furthermore, eddy current losses increase quadratically with the magnetic field frequency. Eddy current heating not only reduces the motor's energy conversion efficiency but also causes the rotor temperature to rise continuously, leading to demagnetization of the permanent magnets and shortening the motor's lifespan.

[0004] Existing publicly available single-pole brushless DC motor designs can prevent the stator alternating magnetic field from passing through the rotor magnetic field, significantly reducing eddy current losses, lowering rotor and magnet temperature rise, and improving motor efficiency. However, this type of motor has the following drawbacks: The rotor drive torque is too low; Cogging torque causes the motor to jerk at low speeds.

[0005] The above-mentioned shortcomings limit its practical application in various scenarios. Summary of the Invention

[0006] To overcome the above-mentioned shortcomings, the purpose of this application is to provide a stator structure for a single-pole motor, thereby effectively solving the above-mentioned technical problems.

[0007] To achieve the above objectives, this application adopts the following technical solution: This application provides a stator structure for a single-pole motor, including a stator assembly and a rotor assembly. The stator assembly includes a stator core, a plurality of stator salient poles disposed on the stator core, windings wound on the stator salient poles, and stator core pole shoes disposed at the ends of the stator salient poles. The rotor assembly includes a magnetic ring and a plurality of magnets uniformly arranged circumferentially along the magnetic ring. The magnetic poles of all the magnets facing the stator assembly have the same polarity. The stator salient poles and windings are deflected circumferentially relative to the center point of symmetry at the ends of the stator core pole shoes, forming a deflection angle, so that the electromagnetic field generated by the windings after being energized has a magnetic field component along the circumferential tangential direction.

[0008] Furthermore, the deflection angle ranges from 0° to 30°.

[0009] Furthermore, the deflection direction of the stator salient pole and winding is either clockwise or counterclockwise.

[0010] Furthermore, the deflection direction is either in the same direction as or opposite to the rotation direction of the rotor assembly, to correspond to different motor output characteristics.

[0011] Furthermore, the rotor assembly is located radially inside the stator assembly to form an inner rotor structure.

[0012] Furthermore, the rotor assembly is located radially outside the stator assembly to form an outer rotor structure.

[0013] Furthermore, the magnet and the magnetic ring form a closed magnetic flux loop.

[0014] Furthermore, three-phase windings with electrical angles of 120° are wound on the stator salient poles.

[0015] Furthermore, the stator core is made of silicon steel sheet, the magnetic ring is made of high permeability metal, and the magnet is made of neodymium iron boron permanent magnet material.

[0016] Furthermore, it also includes a housing, a front motor cover, a rear motor cover, a central shaft, bearings, a three-phase wiring harness, and fastening bolts. The stator assembly is fixed inside the housing, the rotor assembly is supported on the central shaft by the bearings, the front motor cover and the rear motor cover are encapsulated at both ends of the housing by the fastening bolts, and the three-phase wiring harness is electrically connected to the windings.

[0017] Beneficial effects This solution retains the characteristics of a single-pole motor, namely low eddy current loss, small rotor temperature rise, resistance to permanent magnet demagnetization, high motor efficiency, and long service life. It also deflects several stator core salient poles and windings circumferentially from the symmetrical center point at the stator core pole shoe end, forming a deflection angle α. The salient pole windings generate a magnetic field component along the circumferential tangential direction, increasing the force exerted on the rotor in the direction of rotation. Without increasing the mass and cost of the magnets, this solution solves the problem of insufficient torque in traditional single-pole motors, effectively improving the overall performance of the motor and expanding its application scenarios and scope. Attached Figure Description

[0018] The accompanying drawings are provided to illustrate the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure. The shapes and sizes of the components in the drawings do not reflect actual proportions and are only intended to illustrate the content of this application.

[0019] Figure 1The diagram shows the publicly available structure of a single-pole brushless DC motor. Figure 2 A stator structure diagram (internal rotor form) provided for an embodiment of this application; Figure 3 A schematic diagram of the stator structure and magnetic field principle provided in an embodiment of this application; Figure 4 This is a structural diagram of an external rotor motor stator provided in an embodiment of this application.

[0020] In the above attached figures, 1. Stator core; 2. Stator core salient pole and winding; 3. Salient pole magnetic shoe; 4. Magnet; 5. Magnetic ring; 6. Bearing; 7. Central shaft. Detailed Implementation

[0021] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0022] Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In this document, "electrical connection" includes the situation where constituent elements are connected together by an element having some electrical function. There is no particular limitation on the "electrically functioning element," as long as it enables the transmission and reception of electrical signals between the connected constituent elements. An "electrically functioning element" can be, for example, an electrode or wiring, a switching element such as a transistor, or other functional elements such as a resistor, inductor, or capacitor. "Up," "down," "left," and "right" are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0023] In this application, the terms "upper," "lower," "inner," "middle," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Example like Figure 1 The diagram shows a publicly disclosed single-pole brushless DC motor structure. This motor differs from conventional motors in that all magnets 4 have the same polarity facing the stator assembly. This prevents the stator alternating magnetic field from passing through the rotor magnetic field, significantly reducing eddy current losses, lowering rotor and magnet temperature rise, and improving motor efficiency. However, in this structure, the stator salient poles and windings 2 are arranged radially symmetrically along the stator core 1, with the salient pole centerline coinciding with the symmetrical centerline of the pole shoe 3 end. The electromagnetic field generated after the windings are energized is purely radial, and the force exerted on the rotor is mainly radial magnetic pull, with a smaller driving force component along the circumferential tangential direction. Therefore, it suffers from low torque. Furthermore, when the salient poles are arranged radially symmetrically, the gap between adjacent salient poles is large, and the air gap permeability changes drastically along the circumferential direction, resulting in a large cogging torque and causing jerking at low speeds. Figure 1 In the rotor assembly, the stator assembly includes a stator core 1, a stator core salient pole and winding 2, and a stator core pole shoe 3. The rotor assembly includes a magnet 4 and a magnetic ring 5, with the magnetic ring 5 positioned on the central shaft 7 via a bearing 6.

[0025] like Figure 2 The diagram shows the stator structure of the present invention, illustrating an inner rotor structure. The rotor assembly is located radially inside the stator assembly. The stator assembly comprises a stator core 1, several stator core salient poles and windings 2, and stator core pole shoes 3. The rotor assembly includes magnets 4 evenly arranged circumferentially along a magnetic ring 5. All magnets 4 have the same polarity facing the stator assembly. The magnetic ring 5 is positioned on a central shaft 7 via a bearing 6. Figure 1 Compared with the prior art shown, the key difference of the present invention is that the stator salient poles and windings 2 are no longer arranged symmetrically in the radial direction, but are deflected in the circumferential direction relative to the center point of symmetry at the end of the pole shoe. This deflection is the structural basis for increasing the motor torque and reducing the cogging torque.

[0026] The stator core 1 is a ring-shaped structure made of laminated silicon steel sheets of soft magnetic material, possessing excellent magnetic permeability and low iron loss characteristics. The silicon steel sheets are coated with an insulating layer and formed into a single core through a lamination process, effectively reducing eddy current and hysteresis losses under alternating magnetic fields. Multiple stator salient poles extending towards the rotor assembly are evenly arranged circumferentially on the inner ring of the stator core 1. The number of salient poles is determined by the number of phases and pole pairs of the motor. Each stator salient pole is wound with a coil winding, and several stator salient poles are wound with three-phase windings at 120° electrical angles to each other. The three-phase windings are connected in a star or delta configuration. The controller electronically commutates and outputs alternating phase electricity, causing the stator to generate a rotating magnetic field that drives the rotor to rotate. Each stator salient pole has a stator core pole shoe 3 at its end. The pole shoe has a certain width along the circumference to optimize the air gap magnetic field distribution. The pole shoe interacts with the rotor's magnetic poles through the air gap.

[0027] The core improvement of this invention lies in the following: several salient poles and windings 2 of the stator core are deflected circumferentially from the center of symmetry at the end of the stator core pole shoe 3, forming a deflection angle α. The value of this deflection angle ranges from 0° to 30°, and the deflection direction can be clockwise or counterclockwise. The magnitude of the deflection angle α directly affects the magnitude of the tangential magnetic field component B1: the larger the deflection angle, the larger the proportion of the tangential component B1, the stronger the tangential force on the rotor, and the more significant the torque increase; however, when the deflection angle is too large, the radial component B2 is too small, which will lead to a decrease in magnetic circuit efficiency, and excessive salient pole deflection will affect the arrangement space of the windings and the slot fill factor. Therefore, limiting the deflection angle to the range of 0° to 30° can achieve a balance between torque increase and magnetic circuit efficiency. By deflecting the salient poles and windings relative to the center of symmetry of the pole shoe, the direction of the electromagnetic field generated after the salient pole winding is energized is no longer along the pure radial direction, but has a circumferential tilting component.

[0028] like Figure 3 The diagram shows the stator structure and magnetic field principle of the present invention. When the stator salient pole and winding 2 deflect circumferentially from the center of symmetry at the end of the stator core pole shoe 3, forming a deflection angle α, the electromagnetic field B formed by the stator salient pole is vector-decomposed into a component B1 along the circumferential tangent direction and a component B2 along the radial direction. Among them, the magnetic field component B1 along the circumferential tangent direction can enhance the interaction force between the stator magnetic field and the rotor along the circumferential tangent direction, thereby increasing the output torque of the rotor. Figure 3 The diagram also shows the partial structure of magnet 4 and magnetic ring 5 to demonstrate the interaction between the magnetic field generated by the deflection salient pole and the rotor magnetic pole.

[0029] It should be noted that there are two possible states for the deflection direction and the rotor rotation direction: opposite or in the same direction. When the deflection direction is opposite to the rotor rotation direction, the acceleration effect of the tangential magnetic field component B1 on the rotor is more significant, corresponding to low-speed, high-torque output characteristics, suitable for applications requiring high starting torque or heavy-load drive. When the deflection direction is in the same direction as the rotor rotation direction, it corresponds to high-speed, low-torque output characteristics, suitable for high-speed operation and light-load drive applications. By selecting different deflection directions, the motor can be adapted to different application scenarios. The deflection direction of the salient poles can be determined according to the target application scenario during the motor design stage, without the need for additional control algorithms or hardware costs.

[0030] like Figure 4 The diagram shown is a stator structure diagram of an external rotor motor according to one embodiment of the present invention. In this embodiment, the rotor assembly is located radially outside the stator assembly, forming an external rotor structure. The stator assembly still includes a stator core 1, several stator core salient poles and windings 2, and stator core pole shoes 3. The stator core 1 is fixed to a central shaft 7 or a fixed bracket on the housing. The salient poles are evenly distributed along the outer circumference of the stator core 1 and extend outward. The magnets 4 of the rotor assembly are evenly arranged along the circumference of the magnetic ring 5 and have the same polarity facing the stator side. The magnetic ring 5 serves as the outer yoke of the rotor, and the magnets 4 are attached to the inner circumferential surface of the magnetic ring 5. Its working principle is similar to... Figure 3 Similar to the internal rotor motor shown, it generates a tangential magnetic field component through salient pole deflection, increasing rotor torque and reducing cogging torque. The external rotor structure is suitable for applications requiring large rotational inertia or direct load driving, such as hub motors in electric vehicles, external rotor motors for drones, and direct-drive motors for fans. It features a compact structure and high torque density.

[0031] The overall assembly structure and working process of the single-pole motor of the present invention will be described in detail below with reference to an internal rotor embodiment.

[0032] This embodiment is a stator structure of a single-pole motor with an internal rotor, which is composed of three main parts: the housing, the stator assembly, and the rotor assembly.

[0033] The housing serves as the external support and protection structure for the motor, typically made of aluminum alloy or cast iron, providing excellent heat dissipation and mechanical strength. It houses the stator and rotor assemblies. The inner circumferential surface of the housing is interference-fitted with the outer circumferential surface of the stator core 1 or fixedly connected via a heat-shrink fitting, ensuring that the stator assembly does not undergo circumferential displacement during motor operation. The housing has a front end cover 8 and a rear end cover 10 at each end, secured to the housing with bolts 11, forming a closed internal space and providing mounting bases for the bearings 6. The central shaft 7 passes through the center of the rotor assembly and is supported at both ends by bearings 6 within the bearing chambers of the front end cover 8 and the rear end cover 10, allowing the rotor assembly to rotate freely relative to the stator assembly and the housing. Three-phase wiring harness 9 extends from the lead holes in the housing or end covers, electrically connecting to the ends of the stator windings to supply three-phase AC power. Sealing structures are provided at the lead holes to prevent dust and moisture from entering the motor.

[0034] The stator assembly is fixedly mounted on the inner wall of the housing, including a stator core 1, several stator core salient poles and windings 2, and stator core pole shoes 3. The stator core 1 is made of laminated silicon steel sheets of soft magnetic material. The outer ring of the stator core 1 is interference-fitted with the inner ring of the housing to ensure no relative rotation between the stator core 1 and the housing. The inner ring of the stator core 1 is provided with several salient poles, and three-phase windings with electrical angles of 120° are wound on the salient poles. The ends of the windings are led out to the outside of the motor through a three-phase wiring harness 9 and connected to the drive controller. Each salient pole is designed with a stator core pole shoe 3 at its end, which interacts with the magnetic poles of the rotor through an air gap. The several salient poles and windings 2 of the stator core deflect circumferentially from the symmetrical center point at the end of the stator core pole shoe 3, forming a deflection angle α. The deflection direction can be clockwise or counterclockwise, and the value ranges from 0° to 30°.

[0035] The rotor assembly comprises several magnets 4, a magnetic ring 5, and bearings 6. The magnets 4 are evenly spaced along the circumference of the magnetic ring 5, and the number of magnets 4 is designed to match the number of stator salient poles to form a reasonable pole-slot fit. The magnets 4 typically adopt a tile-shaped or rectangular structure and are mounted to the surface of the magnetic ring 5 by adhesive bonding or mechanical fixing. All magnets 4 have the same polarity on the stator side; that is, the side of all magnets 4 facing the stator assembly is either N pole or S pole. This single-pole arrangement is the basis for retaining the low eddy current loss characteristics of this invention. The magnets 4 can be made of neodymium iron boron series strong magnets, which have high energy product and high coercivity. The magnetic ring 5 is made of a metal with high magnetic permeability, such as low-carbon steel or electrical pure iron. The other side of the magnet 4 is in contact with the magnetic ring 5, and the magnetic flux generated by the magnet 4 forms a closed magnetic flux loop between adjacent magnets via the magnetic ring 5. The magnetic ring 5 is positioned and installed on the central shaft 7 via the bearing 6, and the central shaft 7 is then fixedly installed on the end cover of the housing, so that the rotor assembly can rotate freely relative to the stator assembly.

[0036] During operation, the three-phase power supply 9 delivers three-phase alternating current at 120° electrical angles to the stator windings, generating a rotating magnetic field in the stator salient poles and windings 2. Since all magnets 4 have the same polarity facing the stator (either all N poles or all S poles), the stator alternating magnetic field no longer forms a closed loop through the rotor magnets as in conventional motors. Instead, it interacts with the magnet end faces through the air gap and forms a closed magnetic flux loop inside the rotor via the magnetic guide ring 5. This single-pole arrangement ensures that the stator alternating magnetic field does not penetrate the magnet body, thus significantly reducing the eddy current induction effect in the magnets 4, reducing eddy current losses, effectively controlling rotor temperature rise, and preventing demagnetization of permanent magnets due to high temperatures. This improves motor operating efficiency and service life.

[0037] Meanwhile, because the stator salient pole and winding 2 are deflected by an angle 'a' relative to the center of symmetry at the end of the stator core pole shoe 3, the direction of the electromagnetic field B generated by the stator salient pole is no longer purely radial, but tilted at an angle relative to the radial direction. Vector decomposition of this electromagnetic field B can be performed into a component B1 along the circumferential tangential direction and a radial component B2. The tangential component B1 applies an electromagnetic force along the circumferential tangential direction to the rotor magnet 4. This electromagnetic force acts in the direction of rotor rotation, directly driving the rotor to rotate, thereby increasing the motor's output torque. The radial component B2 mainly serves to maintain magnetic circuit continuity and balance radial magnetic pull.

[0038] In implementation, the stator core 1 uses silicon steel sheets, a soft magnetic material. Silicon steel sheets are characterized by high permeability and low iron loss, making them a commonly used material for motor stator cores. The magnetic guide ring 5 is made of a metal with high permeability, such as low-carbon steel or electrical pure iron, which can provide a closed magnetic flux path with low magnetic resistance for the magnet 4, improving magnetic circuit efficiency. The magnet 4 can be made of neodymium iron boron (NdFeB) series strong magnets. NdFeB permanent magnets have the characteristics of high energy product, high coercivity, and high remanence, which can provide a strong magnetic field for the motor, thus improving the power density and torque density of the motor. These material selections are all existing mature motor materials, highly compatible with the existing production process of single-pole motors, requiring no new special processes or equipment, facilitating mass production and assembly.

[0039] The above embodiments retain the original advantages of single-pole motors, such as low eddy current losses, small rotor temperature rise, resistance to permanent magnet demagnetization, high operating efficiency, and long service life. By generating a tangential magnetic field component in the circumferential direction through the stator salient pole and winding deflection angle, the output torque of the motor is increased, solving the problem of insufficient torque in traditional single-pole motors. This structure can adapt to both internal and external rotor forms. The core magnetic circuit design does not require fundamental changes to the rotor form. For motors of different power and size, only the number and size of magnets need to be adjusted for adaptation. It has strong versatility and is highly compatible with existing single-pole motor manufacturing processes, facilitating mass production and assembly. Furthermore, this invention achieves performance improvement through structural improvements without relying on complex control algorithms or additional power electronics. The motor controller can utilize existing mature brushless DC motor drive solutions, reducing overall system cost and development difficulty, and facilitating rapid application.

[0040] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

Claims

1. A stator structure for a single-pole motor, characterized in that: The system includes a stator assembly and a rotor assembly. The stator assembly includes a stator core, a plurality of stator salient poles disposed on the stator core, windings wound on the stator salient poles, and stator core pole shoes disposed at the ends of the stator salient poles. The rotor assembly includes a magnetic ring and a plurality of magnets uniformly arranged circumferentially along the magnetic ring. The magnetic poles of all the magnets facing the stator assembly have the same polarity. The stator salient poles and windings are deflected circumferentially relative to the center point of symmetry of the ends of the stator core pole shoes, forming a deflection angle, so that the electromagnetic field generated by the windings after being energized has a magnetic field component along the circumferential tangential direction.

2. The stator structure of the single-pole motor according to claim 1, characterized in that: The deflection angle ranges from 0° to 30°.

3. The stator structure of the single-pole motor according to claim 1, characterized in that: The deflection direction of the stator salient pole and winding is either clockwise or counterclockwise.

4. The stator structure of the single-pole motor according to claim 3, characterized in that: The deflection direction is either in the same direction as or opposite to the rotation direction of the rotor assembly, to correspond to different motor output characteristics.

5. The stator structure of the single-pole motor according to claim 1, characterized in that: The rotor assembly is located radially inside the stator assembly to form an inner rotor structure.

6. The stator structure of the single-pole motor according to claim 1, characterized in that: The rotor assembly is located radially outside the stator assembly to form an outer rotor structure.

7. The stator structure of the single-pole motor according to claim 1, characterized in that: The magnet and the magnetic ring form a closed magnetic flux loop.

8. The stator structure of the single-pole motor according to claim 1, characterized in that: The stator salient poles are wound with three-phase windings that are 120° electrical angles apart.

9. The stator structure of the single-pole motor according to claim 1, characterized in that: The stator core is made of silicon steel sheet, the magnetic ring is made of high permeability metal, and the magnet is made of neodymium iron boron permanent magnet material.

10. The stator structure of the single-pole motor according to claim 1, characterized in that: It also includes a housing, a front motor cover, a rear motor cover, a central shaft, bearings, a three-phase wiring harness, and fastening bolts. The stator assembly is fixed inside the housing, the rotor assembly is supported on the central shaft by the bearings, the front motor cover and the rear motor cover are sealed to both ends of the housing by the fastening bolts, and the three-phase wiring harness is electrically connected to the windings.

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