Surface-mounted stator permanent magnet doubly salient motor

Abstract

This invention discloses a surface-mounted stator permanent magnet doubly salient pole motor, belonging to the field of motor technology. The motor includes a stator, a rotor, and an air gap. The stator core has stator poles evenly distributed circumferentially, with stator slots formed between adjacent poles. Each stator pole near the air gap contains two permanent magnet poles and one non-permanent magnet pole, with the non-permanent magnet pole located between the two permanent magnet poles. An air magnetic barrier is provided between the permanent magnet poles and the non-permanent magnet poles. The permanent magnet poles are composed of permanent magnets surface-mounted on the surface of the stator pole near the air gap, forming a surface-mounted magnetic pole structure. The permanent magnets are radially magnetized, and all permanent magnets are magnetized in the same direction. The rotor core is made solely of laminated silicon steel sheets, a magnetically conductive material, and has multiple rotor poles. The rotor has no windings or permanent magnets. The windings are concentrated and wound on the stator poles. This invention employs a permanent magnet stator side-mounted structure, which is novel, facilitates processing and assembly, and allows for direct contact between the permanent magnet and the core, resulting in excellent heat dissipation and reducing the risk of temperature rise and demagnetization. The stator core is integrally continuous, providing high structural strength. The rotor is constructed solely of magnetically conductive material, resulting in low inertia and fast dynamic response, making it suitable for high-speed operation. By rationally selecting key parameters such as permanent magnets, non-permanent magnet poles, magnetic barriers, and rotor poles, the winding flux linkage and induced electromotive force can achieve good symmetry and sinusoidal characteristics, making it suitable for high-end manufacturing equipment motors.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a surface-mounted stator permanent magnet double salient pole motor, which is particularly suitable for high-end manufacturing equipment, such as high-speed spindles, industrial robot joints, precision turntables, and other applications with high requirements for dynamic response, reliability, and power density. Background Technology

[0002] Permanent magnet motors are widely used due to their high power density and excellent efficiency. Based on the installation position of the permanent magnets, permanent magnet motors can be divided into rotor permanent magnet type and stator permanent magnet type. Rotor permanent magnet motors place the permanent magnets on the rotor, which can achieve high torque density, but their rotor structure is complex. At high speeds, the permanent magnets are subjected to large centrifugal forces, resulting in insufficient mechanical strength and heat dissipation difficulties. Furthermore, under high temperatures and strong demagnetizing magnetic fields, the permanent magnets are prone to irreversible demagnetization. In addition, the large rotor inertia limits the dynamic response performance of the system.

[0003] Stator permanent magnet motors fix permanent magnets to the stator side, with the rotor consisting only of magnetically conductive material. This results in a simple and robust structure suitable for high-speed operation. Bisalient pole motors feature a stator and rotor bisalient pole structure, with no windings or permanent magnets on the rotor, leading to high reliability. However, traditional stator permanent magnet bisalient pole motors typically employ embedded permanent magnets or complex pole structures, resulting in cumbersome manufacturing processes and long heat dissipation paths for the permanent magnets, leading to significant temperature rise issues. Furthermore, traditional structures have numerous deep stator slots with small individual slot areas, limiting coil placement space. Simultaneously, the deep slots between stator poles cause drastic changes in air gap permeability, resulting in a large number of harmonics in the flux linkage and back electromotive force waveforms, leading to poor sinusoidal characteristics.

[0004] To improve waveform quality, existing technologies typically require fine optimization of the stator and rotor pole arc angles, or the use of complex processes such as skewed poles and magnetic pole reshaping, which significantly increases manufacturing difficulty and cost. Therefore, there is an urgent need to provide a stator permanent magnet motor with a novel structure, ample slot area, excellent waveform quality, good heat dissipation of permanent magnets, fast dynamic response, and suitability for high-speed operation. Summary of the Invention

[0005] The purpose of this invention is to provide a surface-mounted stator permanent magnet bisalient pole motor, which innovatively places the permanent magnets on the stator pole body near the air gap in a surface-mount manner. Each stator pole body forms a composite magnetic pole structure near the air gap, consisting of two permanent magnet poles and one non-permanent magnet pole, and a magnetic barrier is set between the permanent magnet poles and the non-permanent magnet poles. This surface-mounted structure not only significantly simplifies the manufacturing and assembly process and shortens the heat dissipation path of the permanent magnets, but also reduces the number of deep stator slots and increases the slot area while achieving a smooth change in air gap permeability. Furthermore, through parameter optimization, the winding flux linkage and induced electromotive force possess half-wave symmetry and good sinusoidal characteristics.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A surface-mounted stator permanent magnet doubly salient pole motor includes a stator core, a rotor core, permanent magnets, and windings. The stator core includes a stator yoke and multiple stator pole bodies evenly distributed circumferentially, with stator slots formed between adjacent stator pole bodies. The rotor core includes a rotor yoke and multiple rotor poles, with an air gap formed between the rotor poles and the pole faces of the stator pole bodies. Each stator pole body has two permanent magnet poles and one non-permanent magnet pole on one side facing the air gap, with the non-permanent magnet pole located between the two permanent magnet poles, collectively forming the pole face of the stator pole body. A magnetic barrier is provided between the permanent magnet poles and the non-permanent magnet poles. The permanent magnet poles are composed of permanent magnets surface-mounted on the stator pole body near the air gap side, forming a surface-mounted magnetic pole structure. The permanent magnets are radially magnetized, and all permanent magnet poles are magnetized in the same direction. The rotor core is made only of magnetically conductive material, and there are no windings or permanent magnets on the rotor.

[0008] In the above scheme, each stator pole body forms a surface-mounted composite magnetic pole unit, which consists of two radially magnetized permanent magnet poles and one non-permanent magnet pole. The non-permanent magnet pole is located between the two permanent magnet poles and separated from them by a magnetic barrier. The magnetic barrier can be an air barrier or filled with a non-magnetic material. Stator slots are formed between adjacent stator pole bodies to accommodate the winding coil sides. The permanent magnets are directly surface-mounted on the stator pole body surface, in close contact with the iron core, forming an efficient heat conduction path.

[0009] The non-permanent magnet pole can be integrally formed with the stator pole body and stator yoke using the same magnetic material (for example, by stacking silicon steel sheets to form an integral structure), or it can be made of other magnetic materials and then pasted or fixed to the near air gap side surface of the stator pole body.

[0010] Preferably, the permanent magnet pole arc angle is defined as... The non-permanent magnet pole radius is The width of the magnetic barrier arc angle is Then the polar arc angle of each stator pole body satisfy:

[0011]

[0012] The polar arc angle can be flexibly adjusted according to design requirements.

[0013] Preferably, through reasonable selection , , and rotor pole arc angle This minimizes the total harmonic distortion rate of the winding flux linkage or induced electromotive force and ensures that the absolute values ​​of the positive and negative peak values ​​of the flux linkage in each phase are equal.

[0014] The present invention has the following beneficial effects:

[0015] The rotor has a simple structure and is suitable for high-speed operation: the rotor is made of only magnetic material, without windings and permanent magnets, so there is no risk of permanent magnets falling off due to high-speed centrifugal force. It has high mechanical strength and good reliability.

[0016] Low moment of inertia and fast dynamic response: The rotor is lightweight and has low inertia, which helps to improve the dynamic response capability of the motor and meet the needs of high-end manufacturing equipment for rapid start-stop and precise positioning.

[0017] Excellent heat dissipation performance and low risk of demagnetization: The permanent magnet is directly fixed to the surface of the stator pole body by surface mounting and is in direct contact with the stator core. Heat can be quickly conducted to the housing through the pole body and yoke. The heat dissipation path is short and the thermal resistance is small, which effectively reduces the temperature rise of the permanent magnet and significantly reduces the risk of high temperature demagnetization.

[0018] High stator structural strength: The stator pole body and stator yoke can be integrally formed to create a continuous structure, avoiding the weakening of structural strength caused by multiple deep slots in traditional multi-pole structures.

[0019] The manufacturing process is simple and the assembly efficiency is high: the permanent magnet is fixed to the surface of the stator pole body by surface mounting, which does not require complicated embedded positioning and packaging processes. It is suitable for automated mass production, which greatly reduces manufacturing costs and makes it easy to ensure assembly accuracy.

[0020] Large slot area and high slot fill factor: Multiple magnetic pole regions corresponding to each phase winding are integrated into the same pole body, reducing the number of deep slots and increasing the cross-sectional area of ​​a single slot, which is beneficial for coil arrangement and reduces copper loss.

[0021] Excellent waveform quality: By setting magnetic barriers and optimizing parameters, the air gap magnetic permeability changes tend to be smooth, the winding flux linkage and induced electromotive force have good half-wave symmetry and sinusoidal nature, and the total harmonic distortion rate is low.

[0022] Highly scalable: This surface-mount composite magnetic pole structure is not limited to a specific number of phases and poles, and can be extended to motor designs with different numbers of phases and different stator pole numbers. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the radial cross-sectional structure of a surface-mounted stator permanent magnet doubly salient pole motor according to an embodiment of the present invention; Figure 2 A dimensioned diagram showing the unfolded dimensions of the stator and rotor; Figure 3 This is a diagram of the equivalent magnetic circuit model; Figure 4 This is a waveform diagram of the three-phase unloaded flux linkage. Figure 5 The waveform diagram is shown for the three-phase no-load induced electromotive force.

[0024] The markings in the diagram are as follows: 1.1 - stator yoke, 1.2a - stator pole body, 1.2b - permanent magnet pole, 1.2c - non-permanent magnet pole, 1.3 - stator slot, 1.4 - magnetic barrier, 1.5a - A-phase coil, 1.5b - B-phase coil, 1.5c - C-phase coil, 2.1 - rotor yoke, 2.2 - rotor pole. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1: Three-phase four-electrode structure

[0027] like Figure 1 As shown, this embodiment provides a three-phase surface-mounted stator permanent magnet doubly salient pole motor, including a stator core, a rotor core, a shaft, and three-phase windings. The stator core includes a stator yoke 1.1 and three stator pole bodies 1.2a evenly distributed circumferentially, with stator slots 1.3 formed between adjacent stator pole bodies. Each stator pole body 1.2a has two permanent magnet poles 1.2b and one non-permanent magnet pole 1.2c on the side facing the air gap, with the non-permanent magnet pole 1.2c located between the two permanent magnet poles 1.2b. A magnetic barrier 1.4 is provided between the permanent magnet poles 1.2b and the non-permanent magnet poles 1.2c. The permanent magnet poles 1.2b are composed of permanent magnets surface-mounted on the near-air gap side surface of the stator pole body 1.2a, with the permanent magnets radially magnetized, and all permanent magnet poles 1.2b are magnetized in the same direction. The rotor core includes a rotor yoke 2.1 and four rotor poles 2.2, with an air gap formed between the rotor poles 2.2 and the pole faces of the stator pole bodies 1.2a. The rotor core is made solely of laminated silicon steel sheets, and has no windings or permanent magnets. The three-phase windings are A-phase coil 1.5a, B-phase coil 1.5b, and C-phase coil 1.5c, which are wound together on the three stator pole bodies 1.2a, with the coil edges placed within stator slots 1.3.

[0028] In this embodiment, the non-permanent magnet pole 1.2c, the stator pole body 1.2a, and the stator yoke 1.1 are all made of the same silicon steel sheet material, forming an integral structure without the need for additional bonding. The permanent magnet of the permanent magnet pole 1.2b is surface-mounted to the near-air gap side surface of the stator pole body 1.2a, located on both sides of the non-permanent magnet pole 1.2c, with a shallow groove between them serving as a magnetic barrier 1.4. The magnetic barrier 1.4 is an air magnetic barrier, with a radial depth equivalent to the radial thickness of the permanent magnet. This stator structure has high overall strength and can withstand electromagnetic forces and mechanical stresses during high-speed operation. With the permanent magnet surface-mounted to the core surface, heat is rapidly conducted to the housing via the pole body and yoke, resulting in a short heat dissipation path and high thermal management efficiency.

[0029] Figure 2 The unfolded dimensions of the stator and rotor are shown. The permanent magnet pole radius is defined as... The non-permanent magnet pole radius is The width of the magnetic barrier arc angle is The polar arc angle of the stator polar body is The distance between adjacent stator poles is a 120° mechanical angle. The rotor pole pitch is... Mechanical angle, rotor pole arc angle is The air gap length is The polar arc angle of each phase polar surface satisfies:

[0030]

[0031] Figure 3 This is the equivalent magnetic circuit model for this embodiment. Each stator pole body contains two permanent magnet poles and one non-permanent magnet pole. There are a total of nine magnetic pole regions across the three stator pole bodies. Each magnetic pole region corresponds to one branch, and the nine branches are connected in parallel to the stator yoke nodes. and rotor node Between. The non-permanent magnet pole branch contains only air gap permeability. The permanent magnet pole branch includes the magnetic reluctance of the permanent magnet. Air gap magnetic permeability and magnetomotive force source To facilitate parallel magnetic circuit analysis, this invention uses magnetic permeability to describe the equivalent magnetic permeability of each branch. For the first... Each magnetic pole region, branch magnetic flux Branch equivalent magnetic permeability Branch magnetomotive force source Stator yoke node magnetic potential satisfy:

[0032]

[0033] Among them, the non-permanent magnet pole region , Permanent magnet pole region , All branch fluxes satisfy the nodal equations:

[0034]

[0035] The stator yoke node magnetic potential is obtained by solving:

[0036]

[0037] Taking phase A as an example, its magnetic flux linkage is the sum of the magnetic flux in the three magnetic pole regions of the phase A stator pole body:

[0038]

[0039] in The number of coil turns. , , These correspond to the magnetic flux of two permanent magnet poles and one non-permanent magnet pole, respectively.

[0040] The principle by which this invention achieves half-wave symmetry is explained below. The rotor pole pitch is... Mechanical angle, when the rotor rotates half a rotor pole pitch (i.e. At mechanical angle, the air gap permeability of each magnetic pole region on the stator pole body Complementary reversal occurs: the permeability in the non-permanent magnet pole region changes from maximum to minimum, while the permeability in the two permanent magnet pole regions changes from minimum to maximum. Correspondingly, the equivalent permeability of each branch increases. The distribution of magnetic permeability is reversed. However, since the three stator pole bodies have the same structure and are uniformly distributed circumferentially, the total magnetic permeability is... and weighted magnetomotive force The approximate value remains unchanged, therefore the nodal magnetic potential Approximately unchanged. At this point, the signs of the non-permanent magnet pole flux and the two permanent magnet pole fluxes are reversed. With appropriate parameter settings, it can be achieved that:

[0041]

[0042] That is, each phase flux linkage satisfies half-wave symmetry, and the absolute values ​​of the positive and negative peaks are equal.

[0043] Parameter optimization methods

[0044] To obtain the best waveform quality, the present invention can employ the following optimization method:

[0045] The optimization objective is to minimize the total harmonic distortion (THD) of the winding flux linkage or induced electromotive force.

[0046] Optimization variables include: permanent magnet pole radius angle Non-permanent magnet pole arc angle Magnetic barrier arc width Rotor pole arc angle ;

[0047] The constraints include: the polar arc angle of each phase polar face. To meet structural rationality, air gap length The thickness of the permanent magnet meets the magnetic circuit requirements;

[0048] A set of parameters is obtained by iteratively solving the problem using finite element simulation or analytical magnetic circuit model, which minimizes THD and optimizes the symmetry of positive and negative peak values.

[0049] It should be noted that the optimization parameters are not limited to specific values ​​and can be adjusted according to different design requirements.

[0050] By optimizing the parameters mentioned above, we can obtain the following: Figure 4 and Figure 5 The ideal waveform shown. Figure 4The waveform of the three-phase unloaded flux linkage in this embodiment is shown. The phase difference between the three-phase flux linkages is 120° electrical degrees, and the absolute values ​​of the positive and negative peak values ​​of each phase flux linkage are equal, exhibiting good half-wave symmetry. Figure 5 The corresponding three-phase no-load induced electromotive force waveforms show equal amplitudes and symmetrical phases across the three phases, exhibiting good sinusoidal characteristics without obvious peaks or flat tops. These results verify the effectiveness of the surface-mount structure and optimization method proposed in this invention.

[0051] Other embodiments

[0052] The present invention is not limited to the specific structures described in the above embodiments.

[0053] Example 2: Composite magnetic pole structure consisting of two non-permanent magnet poles sandwiching one permanent magnet pole

[0054] In another embodiment, each stator pole body may have two non-permanent magnet poles and one permanent magnet pole on the side facing the air gap. The permanent magnet pole is located between the two non-permanent magnet poles, and a magnetic barrier is set between the permanent magnet pole and the non-permanent magnet poles; all permanent magnet poles are magnetized in the same direction. This variant structure can also achieve reasonable changes in air gap permeability through magnetic barrier and parameter optimization, so that each phase flux linkage has half-wave symmetry and sinusoidal properties. The non-permanent magnet poles can be integrally formed with the stator pole body and stator yoke, or manufactured separately and fixed to the stator pole body near the air gap.

[0055] Expansion of pole number and phase number

[0056] This invention is not limited to a three-phase four-pole structure. In different embodiments, the number of stator poles, the number of rotor poles, and the number of phases can be adjusted as needed. For generalization, let the number of motor phases be 1. The number of lumped coils connected in series in each phase is Then the total number of stator poles (i.e., the total number of condensed coils) satisfy:

[0057]

[0058] Each stator pole is evenly distributed along the circumference, and the mechanical angle between adjacent stator poles is:

[0059]

[0060] Let the number of rotor poles be The electrical angle difference between adjacent stator poles is:

[0061]

[0062] To ensure In a symmetrical manner, the induced electromotive forces of different phases should differ sequentially in electrical angle. Usually, this can be achieved through reasonable selection. and This can be achieved through combinations of [various methods]. For example, when [the specific method is missing]. hour, It is acceptable or This embodiment corresponds to The four-pole structure; when hour, It is acceptable or ;when hour, It is acceptable or Furthermore, each phase coil can be connected in series, in parallel, or a combination of series and parallel connections. As long as each stator pole body has two permanent magnet poles and one non-permanent magnet pole (or two non-permanent magnet poles and one permanent magnet pole) on the side facing the air gap, and a magnetic barrier is provided between the permanent magnet poles and the non-permanent magnet poles, it falls within the protection scope of this invention.

[0063] In alternative embodiments, the magnetic barrier 1.4 can be made of air or filled with a non-magnetic material; the permanent magnet pole 1.2b can be radially magnetized or parallel magnetized; the stator slot 1.3 can be an open slot, a semi-closed slot, or a closed slot; the rotor pole 2.2 can be skewed to reduce cogging torque. When the non-permanent magnet pole 1.2c uses a different magnetic material than the stator pole body, it can be manufactured separately and then glued or mechanically fixed to the stator pole body near the air gap side. All the above modifications fall within the protection scope of this invention.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of 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 surface-mounted stator permanent magnet doubly salient pole motor, comprising a stator core, a rotor core, permanent magnets, and windings; The stator core includes a stator yoke (1.1) and a plurality of stator poles (1.2a) evenly distributed along the circumference, with stator slots (1.3) formed between adjacent stator poles (1.2a). The rotor core includes a rotor yoke (2.1) and a plurality of rotor poles (2.2), and an air gap is formed between the rotor poles (2.2) and the pole faces of the stator pole body (1.2a); Its features are, Each of the stator pole bodies (1.2a) has two permanent magnet poles (1.2b) and one non-permanent magnet pole (1.2c) on the side facing the air gap, forming the pole surface of the stator pole body (1.2a), and the non-permanent magnet pole (1.2c) is located between the two permanent magnet poles (1.2b); A magnetic barrier (1.4) is provided between the permanent magnet pole (1.2b) and the non-permanent magnet pole (1.2c). The permanent magnet pole (1.2b) is composed of a permanent magnet attached to the surface of the stator pole body (1.2a) near the air gap, forming a surface-mounted magnetic pole structure. The permanent magnet is radially magnetized, and all the permanent magnet poles (1.2b) are magnetized in the same direction. The rotor core is made of only magnetically conductive material, and there are no windings or permanent magnets on the rotor.

2. The surface-mounted stator permanent magnet doubly salient pole motor according to claim 1, characterized in that, The magnetic barrier (1.4) is an air magnetic barrier or a shallow groove structure filled with non-magnetic material.

3. The surface-mounted stator permanent magnet doubly salient pole motor according to claim 1, characterized in that, The stator poles (1.2a) are evenly distributed along the circumference; the rotor poles (2.2) are evenly distributed along the circumference; the windings are coils that are respectively wound on the stator poles (1.2a).

4. The surface-mounted stator permanent magnet doubly salient pole motor according to claim 3, characterized in that, The induced electromotive forces of the windings are symmetrical.

5. The surface-mounted stator permanent magnet doubly salient pole motor according to claim 1, characterized in that, Define the permanent magnet pole arc angle as The non-permanent magnet pole radius is The width of the magnetic barrier arc angle is Then the polar arc angle of each stator pole body (1.2a) satisfy:

6. The surface-mounted stator permanent magnet doubly salient pole motor according to claim 3, characterized in that, By optimizing the permanent magnet pole arc angle Non-permanent magnet pole arc angle Magnetic barrier arc width and rotor pole arc angle This ensures that when the rotor rotates by half the rotor pole pitch, the absolute values ​​of the positive and negative peak values ​​of the magnetic flux of each phase winding are equal, thus achieving half-wave symmetry.

7. The surface-mounted stator permanent magnet doubly salient pole motor according to claim 5, characterized in that, The permanent magnet pole arc angle Non-permanent magnet pole arc angle Magnetic barrier arc width and rotor pole arc angle It is chosen to minimize the total harmonic distortion rate of the winding flux linkage or induced electromotive force.

8. The surface-mounted stator permanent magnet doubly salient pole motor according to any one of claims 1 to 6, characterized in that, The stator slot (1.3) is a deep slot, and the radial depth of the magnetic barrier (1.4) is less than the radial depth of the stator slot (1.3) and is equivalent to the radial thickness of the permanent magnet.

9. The surface-mounted stator permanent magnet doubly salient pole motor according to any one of claims 1 to 6, characterized in that, The permanent magnet material is neodymium iron boron or samarium cobalt permanent magnet material, and the non-permanent magnet pole (1.2c) is made of silicon steel sheet lamination or magnetically conductive composite material.

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