Stator tooth structure switching type high-torque permanent magnet synchronous motor

Abstract

The invention discloses a stator tooth structure switching type high-torque permanent magnet synchronous motor which is composed of a permanent magnet rotor and an armature stator, and a cold-pressed iron-silicon-aluminum powder core block is embedded in each stator tooth top. Due to the fact that the current value in the armature winding is increased due to working condition switching, the temperature rise of the iron-silicon-aluminum powder core block can be increased, the magnetic conductivity of the iron-silicon-aluminum powder core block at the stator tooth crest is different from that of the stator tooth crest, and each stator tooth forms an equivalent field modulation ring structure. The motor body is switched from a permanent magnet synchronous motor to a magnetic field modulation motor for operation in a self-adaptive mode due to working condition changes, and high torque can be output based on the magnetic gear effect. The permanent magnet synchronous motor has the inherent characteristics of high power factor, high efficiency and the like under the low torque requirement, and when the working condition is switched to the high torque requirement, the stator tooth structure is structurally switched along with the armature current amplitude, a formed magnetic field modulates the motor to output high torque, and the problem that the torque output capacity of the motor is limited under the high torque requirement is solved.

Description

Technical Field

[0001] This invention relates to a high-torque permanent magnet synchronous motor with a stator tooth structure switching type. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) rely on the synchronous coupling of the armature current magnetic field and the rotating magnetic field of the rotor's permanent magnet excitation to output steady-state torque. They offer advantages such as low manufacturing cost, high power factor, and high efficiency, making them a significant alternative to traditional electrically excited motors and widely used in aerospace, space exploration, and industrial production. Currently, rising industrial demands are placing higher requirements on the torque density of PMSMs. Traditional PMSMs face problems such as excessive permanent magnet usage and large size. High permanent magnet usage can cause local magnetic saturation in the motor, preventing further increases in output torque. In engineering, most motor systems employ a combination of high-speed motors and mechanical gears to improve the torque density of the drive system. However, this combination leads to significant frictional losses, lower operating efficiency, and a series of other problems.

[0003] In recent years, permanent magnet synchronous motors (IPMSMs) have made significant progress in electromagnetic structure design. Professor Liu Guohai's team at Jiangsu University modified the uniform air gap of the traditional V-type built-in permanent magnet synchronous motor (IPMSM) to a periodically varying non-uniform air gap. By optimizing parameters such as the pole arc coefficient and air gap length using the Taguchi method, the optimized design resulted in a 30% reduction in cogging torque and a 15% increase in average output torque compared to the prototype motor. It also improved the air gap magnetic flux density waveform and reduced back EMF harmonic distortion. The permanent magnet in this design is an integral ring structure, installed on the inner wall of a square motor housing. This avoids the positioning errors and magnetic leakage problems of traditional segmented permanent magnets. However, the non-uniform air gap requires strict tolerance control; otherwise, it can easily lead to magnetic field asymmetry. Furthermore, the integrated permanent magnet requires a customized magnetization process, resulting in higher costs. Rotor heat dissipation is also difficult, and high temperatures may cause demagnetization of the permanent magnet.

[0004] Professor Hua Wei's team at Southeast University directly mounted permanent magnets on the surface of the stator teeth, instead of the traditional rotor side. By symmetrically distributing the stator salient poles and concentrated windings, they offset the high-order harmonic induced electromotive force and improved the sinusoidal nature of the no-load induced electromotive force. They adopted an asymmetrical stator tooth design to solve the problem of magnetic circuit asymmetry in traditional dual salient pole permanent magnet motors (DSPMs), reducing torque ripple by 40%. However, despite the reduction in ripple after optimization, the skewed rotor design still has a torque fluctuation of 5% to 8%, which requires complex control strategies to suppress. Furthermore, it relies on electric excitation in the high-speed region, and its dynamic response is slower than that of a magnetic field modulation motor.

[0005] Currently, optimizing the structure and placement space of permanent magnets can effectively improve the fundamental frequency of air gap magnetic flux density in permanent magnet synchronous motors. However, the limited placement space for permanent magnets and the constraints on their size imposed by other factors greatly limit the ability to improve torque simply by designing the permanent magnet structure. Summary of the Invention

[0006] The purpose of this invention is to provide a high-torque permanent magnet synchronous motor with a stator tooth structure switching type. By embedding a low-knee iron-silicon-aluminum powder core block at the tip of each stator tooth, the temperature of the iron-silicon-aluminum powder core block can be increased due to the increased current value in the armature winding required for operating condition switching. This causes a difference in the permeability of the iron-silicon-aluminum powder core block at the stator tooth tip and the stator tooth tip itself. The permeability of the iron-silicon-aluminum powder core block is significantly reduced. After the iron-silicon-aluminum powder core block is saturated, each stator tooth forms an equivalent field modulation ring structure. The permanent magnet synchronous motor can adaptively switch to field modulation motor operation due to changes in operating conditions, thereby enhancing the output torque of the motor.

[0007] This invention provides a high-torque permanent magnet synchronous motor with a stator tooth structure switching type, comprising: The main body of the motor includes the stator and the rotor; The armature winding is placed in the stator slot between adjacent stator teeth; Iron-silicon-aluminum powder core blocks are embedded at the top of stator teeth; the temperature coefficient of the magnetic permeability of the iron-silicon-aluminum powder core blocks is higher than that of the stator teeth. The increased current in the armature winding due to the change in operating conditions can raise the temperature of the iron-silicon-aluminum powder core, causing a difference in the permeability of the iron-silicon-aluminum powder core at the stator tooth tip and the stator tooth tip. Each stator tooth forms an equivalent field modulation ring structure. The motor body adapts to the change in operating conditions by switching from a permanent magnet synchronous motor to a field modulation motor.

[0008] Optionally, the width and number of iron-silicon-aluminum powder core blocks are determined by the torque required for the motor application conditions.

[0009] Optionally, when the temperature coefficient of the iron-silicon-aluminum powder core is negative, the magnetic flux density at which the iron-silicon-aluminum powder core becomes magnetically saturated under design conditions is 0.5 times that of the stator tooth tip; when the temperature coefficient of the iron-silicon-aluminum powder core is positive, the magnetic flux density at which the stator tooth tip becomes magnetically saturated under design conditions is 0.5 times that of the iron-silicon-aluminum powder core.

[0010] Optionally, the iron-silicon-aluminum powder core blocks are multiple and are respectively embedded at each equally spaced point on the stator tooth tip.

[0011] Optionally, the iron-silicon-aluminum powder core block can be any geometric shape among trapezoidal, triangular, and curved rectangle.

[0012] Optionally, the iron-silicon-aluminum powder core block has an axially stacked structure; the stacked sheets formed by axial stacking are made of one or more materials selected from iron-cobalt alloy, iron-nickel alloy, and permalloy.

[0013] Optionally, the permanent magnets on the rotor are arranged in a circumferential array.

[0014] Optionally, the permanent magnet can be surface-mounted, embedded, or in Halbach form.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention embeds low-knee-point iron-silicon-aluminum powder core blocks at the tip of each stator tooth in a traditional permanent magnet motor. Due to the increased current value in the armature winding required for operating condition switching, the temperature of the iron-silicon-aluminum powder core blocks rises, causing a difference in the permeability of the iron-silicon-aluminum powder core blocks at the stator tooth tip and the stator tooth tip. The permeability of the iron-silicon-aluminum powder core blocks is significantly reduced, and a single stator tooth forms an equivalent field modulation ring structure, modulating the air gap magnetic flux density harmonics. The permanent magnet synchronous motor can adaptively switch to field modulation motor operation due to changes in operating conditions, thereby enhancing the output torque to meet the operating condition requirements.

[0016] 2. This invention, by setting different stator tooth tip positions and numbers of iron-silicon-aluminum powder core blocks, can modulate multiple coupled harmonics to meet the motor operating requirements under different load conditions in conjunction with different pole slots. The actual arrangement of the iron-silicon-aluminum powder core blocks can be determined according to the torque required for the corresponding motor application conditions. Simultaneously, using a combination of various knee-point core materials can effectively reduce the production cost of the stator core and effectively increase the torque density of the motor. Furthermore, the stator tooth structure switching structure of this invention is applicable to both rotor permanent magnet motors and stator permanent magnet motors.

[0017] 3. The motor of the present invention has high output torque and low torque pulsation. The stator tooth structure switching type permanent magnet motor can edit the stator air gap magnetic permeability, target and increase the working harmonics of the air gap magnetic field, effectively reduce non-working harmonics and harmonic distortion, and improve the output performance of the motor.

[0018] 4. The motor of this invention has heavy-load starting and instantaneous torque burst performance. The stator gear structure switching type permanent magnet motor can effectively reduce non-working harmonics and harmonic distortion, improve the motor's heavy-load starting capability, and reduce the vibration and noise of the mechanical gearbox. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the radial cross-sectional structure of a high-torque permanent magnet motor with a stator tooth structure switching type provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the radial cross-sectional structure of a high-torque permanent magnet motor with different shapes and numbers of stator teeth, provided in an embodiment of the present invention. Figure 3 This is a three-dimensional structural diagram of the stator core and alternating poles in a high-torque permanent magnet motor with a stator tooth structure switching type, provided in an embodiment of the present invention.

[0020] Numbering on the map: 1. Stator; 101. Stator core; 101-1. Iron-silicon-aluminum powder core block; 101-2. Stator tooth tip; 102. Armature winding; 104. Flat-topped stator tooth; 105. "Concave" shaped stator tooth; 2. Rotor; 201. Permanent magnet; 201-1. S pole; 202. Rotor core; 203. Shaft. Detailed Implementation

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," 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. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0023] To make the purpose, technical solution and advantages of this invention patent clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, this embodiment discloses a high-torque permanent magnet synchronous motor with a stator tooth structure switching type, including a stator 1 and a rotor 2. The stator 1 includes a stator core 101, stator tooth tips 101-2, and an armature winding 102. The rotor 2 includes a permanent magnet 201, a rotor core 202, and a shaft 203, wherein the permanent magnet 201 is disposed on the surface of the rotor core 202.

[0025] Each stator tooth tip 101-2 is embedded with a low-knee iron-silicon-aluminum powder core block 101-1. In a specific embodiment, the iron-silicon-aluminum powder core block 101-1 is embedded at the center of the stator tooth tip 101-2, and each stator tooth can be electromagnetically reconfigured to form two magnetic circuit branches. The iron-silicon-aluminum powder core block 101-1 is cold-pressed from Fe (85%), Si (9%), and Al (6%) powder, and has a lower saturation magnetic flux density compared to the conventional silicon steel used in the stator tooth tip 101-2; the temperature coefficient of the magnetic permeability of the iron-silicon-aluminum powder core block 101-1 is higher than that of the stator tooth tip 101-2. In one specific embodiment, when the temperature coefficient of the iron-silicon-aluminum powder core 101-1 is negative, the magnetic flux density at which the iron-silicon-aluminum powder core 101-1 achieves magnetic saturation under design conditions is 0.5 times that of the stator tooth tip 101-2; when the temperature coefficient of the iron-silicon-aluminum powder core 101-1 is positive, the magnetic flux density at which the stator tooth tip 101-2 achieves magnetic saturation under design conditions is 0.5 times that of the iron-silicon-aluminum powder core 101-1.

[0026] Specifically, the increased current in the armature winding 102 due to the change in operating conditions causes the temperature of the iron-silicon-aluminum powder core block 101-1 to rise, resulting in a difference in the permeability of the iron-silicon-aluminum powder core block 101-1 at the stator tooth tip 101-2 compared to the stator tooth tip 101-2. Each stator tooth 101 forms an equivalent field modulation ring structure, and the motor body adaptively switches from permanent magnet synchronous motor to field modulation motor operation due to the change in operating conditions. Furthermore, the width and number of the iron-silicon-aluminum powder core blocks 101-1 are determined by the torque required for the corresponding motor application conditions. Multiple iron-silicon-aluminum powder core blocks 101-1 can be embedded at various equally spaced points on the stator tooth tip 101-2, so that each stator tooth 101 forms multiple magnetic circuit branches, thereby modulating multiple coupled harmonics to meet the motor operation requirements under different load conditions in conjunction with different pole slots.

[0027] Combination Figure 1 Under low armature current, the stator teeth are flat-topped stator teeth 104. Due to the change in operating conditions, the low armature current increases to the required high armature current, and the temperature of the iron-silicon-aluminum powder core block 101-1 rises. This causes a difference in the permeability of the iron-silicon-aluminum powder core block 101-1 at the stator tooth top 101-2 compared to the stator tooth top 101-2. Only the iron-silicon-aluminum powder core block 101-1 at the low knee point of the stator tooth top 101-2 experiences magnetic saturation, and the stator teeth become concave stator teeth 105. Each stator tooth 101 forms an equivalent field modulation ring structure. The dual electromagnetic structure of the flat-topped stator teeth 104 and the concave stator teeth 105 can adaptively switch according to the change in armature current value during the change in operating conditions. The motor body adaptively switches from permanent magnet synchronous motor to magnetic field modulation motor operation due to the change in operating conditions.

[0028] like Figure 1As shown, in a specific embodiment, the stator teeth of the 12-slot 10-pole permanent magnet synchronous motor are flat-topped stator teeth 104 under small armature current, wherein the number of pole pairs of the armature winding and the number of pole pairs of the permanent magnet are 5, which satisfies the operating principle of synchronous motor. Under large armature current, the stator teeth are concave stator teeth 105, and one stator tooth is electromagnetically reconstructed to form two teeth, or two magnetic circuit branches. To further explain the concave stator teeth 105, when the current value in the armature winding 102 increases, the iron-silicon-aluminum powder core block 101-1 at the low knee point will saturate. After saturation, it no longer conducts magnetism, which is equivalent to this block becoming air (the solid structure still exists). Functionally, the air block in the middle of the stator tooth top 101-2 is reconstructed to form stator teeth as two magnetic circuit branches. The two stator teeth have a modulation effect compared to one tooth, so the motor can work as a magnetic field modulation motor. Taking the initial 12 stator teeth as an example, after the iron-silicon-aluminum powder core block 101-1 is saturated, it can actually be equivalent to 24 teeth to play a modulation role. In the air gap magnetic field between stator 1 and rotor 2, the 19th, 9th and 5th major working harmonics can be modulated to enhance the torque output of the motor.

[0029] In one specific embodiment, when the temperature coefficient of the iron-silicon-aluminum powder core 101-1 is negative, the magnetic flux density at which the iron-silicon-aluminum powder core 101-1 achieves magnetic saturation under design conditions is 0.5 times that of the stator tooth tip 101-2; when the temperature coefficient of the iron-silicon-aluminum powder core 101-1 is positive, the magnetic flux density at which the stator tooth tip 101-2 achieves magnetic saturation under design conditions is 0.5 times that of the iron-silicon-aluminum powder core 101-1.

[0030] To illustrate with a specific example, the saturation points of the conventional iron cores used in the iron-silicon-aluminum powder core block 101-1 and the stator tooth tip 101-2 differ. The iron-silicon-aluminum powder core block 101-1 with a low knee saturation point saturates at 1.2T, while the conventional iron core saturates at 1.6T. Due to the change in operating conditions, the current value in the armature winding 102 increases. When the magnetic field strength exceeds 1.2T, the iron-silicon-aluminum powder core block 101-1 becomes magnetically saturated and loses its magnetic conductivity, while the conventional iron core of the stator tooth tip 101-2 continues to operate normally. After the current value in the armature winding 102 decreases, the magnetic conductivity of the iron-silicon-aluminum powder core block 101-1 with a low knee saturation point can be fully restored for multiple cycles of use. According to the motor operating principle, after the iron-silicon-aluminum powder core block 101-1 saturates, the permanent magnet synchronous motor switches to magnetic field modulation motor operation and outputs high torque based on the magnetic gear effect.

[0031] To illustrate with a specific application scenario, when switching from rated operating conditions to heavy-load operating conditions, the current value of the armature winding 102 increases due to the change in operating conditions, causing magnetic saturation of the iron-silicon-aluminum powder core block 101-1, and a structural switch occurs at the stator tooth tip 101-2. The motor body switches from a permanent magnet synchronous motor to a magnetic field modulation motor to meet the high torque requirements under heavy-load conditions.

[0032] like Figure 2 As shown, the low-knee iron-silicon-aluminum powder core block 101-1 is an axially stacked structure. The arrangement of silicon steel material within the stack is determined by the radial distribution of the magnetic field within the motor at this axial position in three-dimensional space. The stack can be made of various materials such as iron-cobalt alloy, iron-nickel alloy, and permalloy. The low-knee iron-silicon-aluminum powder core block 101-1 can adopt any special geometric shape such as trapezoidal, triangular, or curved rectangle. At the same time, the low-knee iron-silicon-aluminum powder core block structure with different stator tooth tip positions and numbers can modulate multiple coupled harmonics to meet different pole-slot combinations, thereby meeting the motor operation requirements under different load conditions.

[0033] like Figure 2 As shown, the permanent magnets 201 are arranged in a circular pattern and can be formed by subtractive manufacturing and bonding. The permanent magnets 201 on the rotor 2 adopt an alternating pole structure. Utilizing the characteristic that the magnetic core can converge magnetic lines of force to form magnetic poles, a hybrid magnetic pole structure is formed by replacing some permanent magnet poles with iron core poles. The N pole is made of neodymium iron boron material, and the S poles 201-1 are all replaced by iron cores. By appropriately increasing the pole arc coefficient and magnet thickness of the permanent magnet poles, the alternating pole motor can significantly reduce the amount of permanent magnets used with a small torque loss, effectively reducing the motor production cost.

[0034] like Figure 2 As shown, the armature winding 102 adopts a fractional-slot concentrated winding, which is wound on the stator teeth. In this embodiment, since the ends of the fractional-slot concentrated winding are shorter than those of the traditional distributed winding, the copper loss is low, which helps to reduce the temperature rise when the motor is under load.

[0035] like Figure 3 As shown, the equivalent air gap width can be precisely controlled by adjusting the current; the stator tooth switching structure modulates and controls the harmonic distribution of the air gap magnetic field inside the motor, which is used to reduce the harmonic distortion of the air gap magnetic field, improve the torque characteristics and expand the motor operating characteristics; when the motor is unloaded, the flat-top stator tooth 104 is used to reduce the cogging torque of the motor and make the no-load back EMF waveform sinusoidal; when the motor is loaded, the concave stator tooth 105 is used to reduce the torque pulsation of the motor and increase the output torque.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-torque permanent magnet synchronous motor with a stator gear structure switching type, comprising: The motor body includes a stator (1) and a rotor (2); The armature winding (102) is placed in the stator slot between adjacent stator teeth; A metal-silicon-aluminum powder core block (101-1) is embedded at the stator tooth tip (101-2); the temperature coefficient of the magnetic permeability of the metal-silicon-aluminum powder core block (101-1) is higher than that of the stator tooth tip (101-2); The feature is that the increased current value in the armature winding (102) due to the change in operating conditions can cause the temperature of the iron-silicon-aluminum powder core block (101-1) to rise, resulting in a difference between the permeability of the iron-silicon-aluminum powder core block (101-1) at the stator tooth tip (101-2) and the stator tooth tip (101-2). Each stator tooth (101) forms an equivalent field modulation ring structure. The motor body adapts to the change in operating conditions by switching from a permanent magnet synchronous motor to a magnetic field modulation motor.

2. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, The width and quantity of the iron-silicon-aluminum powder core (101-1) are determined by the torque required for the motor application conditions.

3. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, When the temperature coefficient of the iron-silicon-aluminum powder core block (101-1) is negative, the magnetic flux density at which the iron-silicon-aluminum powder core block (101-1) reaches magnetic saturation under design conditions is 0.5 times that of the stator tooth tip (101-2); when the temperature coefficient of the iron-silicon-aluminum powder core block (101-1) is positive, the magnetic flux density at which the stator tooth tip (101-2) reaches magnetic saturation under design conditions is 0.5 times that of the iron-silicon-aluminum powder core block (101-1).

4. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, The iron-silicon-aluminum powder core block (101-1) is multiple and is respectively embedded at each of the equal division points of the stator tooth top (101-2).

5. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, The iron-silicon-aluminum powder core block (101-1) adopts any geometric shape among trapezoids, triangles, and curved rectangles.

6. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, The iron-silicon-aluminum powder core block (101-1) has an axially stacked structure; the stacked sheets formed by axial stacking are made of one or more materials selected from iron-cobalt alloy, iron-nickel alloy, and permalloy.

7. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, The permanent magnets (201) on the rotor (2) are arranged in a circular array.

8. The high-torque permanent magnet synchronous motor with stator gear structure switching according to claim 1, characterized in that, The permanent magnet (201) is available in surface-mount, built-in, and Halbach configurations.

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