A movable rotor lamination topology for driving an electric machine

Abstract

The present application relates to the technical field of motor, in particular to a movable rotor lamination topology of driving motor, comprising a plurality of coaxially stacked rotor laminations, each of which is provided with a first magnetic steel groove and a second magnetic steel groove in V-shaped distribution, and a sliding magnetic steel groove located in the middle of the pair of second magnetic steel grooves. The sliding magnetic steel groove is a rectangular groove, in which a movable magnetic steel block that can move radially is installed; the outer side of the inner end of the sliding magnetic steel groove is provided with a third magnetic steel groove, in which a fixed magnetic steel block is fixedly installed. The present application uses high-speed centrifugal force to make the movable magnetic steel block move outward along the radial direction, reduces the permanent magnet flux linkage, and replaces the traditional electric weak magnetic mode; at low speed, the movable magnetic steel block is reset by the magnetic attraction force of the fixed magnetic steel block, and a large permanent magnet flux linkage is maintained. The topology realizes the self-adaptive adjustment of the magnetic circuit characteristics with the rotating speed, fundamentally solves the contradiction between the large torque at low speed and the weak magnetic speed expansion at high speed of the permanent magnet synchronous motor, and has the advantages of low high-speed copper loss, high efficiency, simple structure and easy engineering implementation.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically to a movable rotor lamination topology for a drive motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in new energy vehicles, aerospace, high-speed machine tools, and other fields due to their advantages such as high power density, high efficiency, and high torque density. Currently, the mainstream rotor topology of PMSMs mainly involves embedding permanent magnets in magnetic slots inside the rotor core. Depending on the shape of the magnetic slots, various topologies can be categorized, including straight-line, V-type, U-type, and W-type. The built-in structure utilizes the salient pole effect of the rotor core to generate reluctance torque, resulting in higher torque density. Furthermore, since the permanent magnets are encased in the core, the centrifugal force at high speeds is borne by the core, leading to higher mechanical strength and superior field weakening and speed-enhancing capabilities compared to surface-mounted structures.

[0003] Furthermore, existing technologies have developed improved solutions such as segmented magnet rotors, hybrid excitation rotors, and axially laminated rotors to further enhance high-speed performance. However, the core commonality of all these solutions is that the position of the permanent magnet in the rotor core remains fixed, and the magnetic circuit characteristics remain constant throughout the entire speed range of the motor. This means that the permanent magnet flux linkage of the motor is a fixed design value and cannot be dynamically adjusted according to changes in speed.

[0004] This traditional rotor topology with a fixed magnet position has the following significant drawbacks:

[0005] 1) The contradiction between the demand for high torque at low speeds and the demand for field weakening at high speeds: Under low-speed conditions, to obtain high torque, the permanent magnet needs to provide the largest possible permanent magnet flux linkage; however, under high-speed conditions, an excessively large permanent magnet flux linkage will cause the back electromotive force to rise sharply, exceeding the inverter's voltage limit. A large amount of d-axis field weakening current must be injected to counteract the permanent magnet magnetic field. This field weakening current not only generates significant copper losses, reducing the high-speed efficiency of the motor, but also increases the inverter's capacity requirements, raising system costs.

[0006] 2) The contradiction between high-speed mechanical strength and electromagnetic performance: In order to withstand high-speed centrifugal force, the built-in rotor needs to retain a sufficiently thick iron core magnetic bridge outside the magnet slot, but the magnetic bridge will generate magnetic leakage, reducing the utilization rate of permanent magnets; the sheath of the surface-mounted rotor will increase the air gap length, which will also reduce electromagnetic performance.

[0007] 3) Limited optimization of efficiency map: The fixed magnetic circuit characteristics mean that the motor can only achieve the highest efficiency within a narrow speed-torque range, which cannot cover the operating conditions of new energy vehicles that require a wide speed range, thus affecting the overall vehicle range.

[0008] In summary, how to achieve adaptive adjustment of the magnetic circuit characteristics of permanent magnet synchronous motors with rotational speed, and fundamentally solve the contradiction between low-speed high torque and high-speed field weakening speed expansion, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies where the position of permanent magnets is fixed and the magnetic circuit characteristics cannot be dynamically adjusted with rotational speed, and to provide a movable rotor lamination topology for drive motors. It aims to solve the following technical problems: 1) the inability to simultaneously achieve high-speed and low-speed electromagnetic performance in permanent magnet synchronous motors, realizing a balance between low-speed high torque and high-speed high efficiency with a wide field-weakening range; 2) the problem of low efficiency and wasted inverter capacity due to excessive field-weakening current under high-speed operating conditions; 3) the problems of complex structure, difficult control, and limited engineering implementation of existing movable magnet solutions.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a movable rotor lamination topology for a drive motor, comprising: multiple rotor laminations, wherein the multiple rotor laminations are coaxially stacked sequentially; each rotor lamination is provided with a first magnet slot, a second magnet slot, and a sliding magnet slot. Two symmetrically arranged first magnet slots are distributed in a V-shape, and a first magnet passes through the first magnet slot; two symmetrically arranged second magnet slots are distributed in a V-shape, and a second magnet passes through the second magnet slot. The sliding magnet slot is located in the middle of a pair of second magnet slots, with its outer end close to the inner end of the first magnet slot and its inner end close to the inner end of the second magnet slot. The sliding magnet slot is a rectangular slot, and a movable magnet block capable of radial movement is installed inside it. The inner end of the sliding magnet groove also has a third magnet groove. The third magnet groove has a rectangular structure and a fixed magnet block is fixedly installed inside it. The fixed magnet block corresponds to the movable magnet block inside the sliding magnet groove.

[0011] As a preferred technical solution, the width of the sliding magnet groove is denoted as W1, and the thickness of the second magnet groove is denoted as W3, satisfying: 2mm ≤ W1 ≤ W3 + 1mm; the distance between the sliding magnet groove and the inner side of the first magnet groove is D1, D1 ≥ 1mm; the distance between the sliding magnet groove and the inner side of the second magnet groove is D2, D2 ≤ 2mm; and the distance between the sliding magnet groove and the second magnet groove is D3, 0.6mm ≤ D3 ≤ 2mm.

[0012] As a preferred technical solution, the width of the fixed magnet block is denoted as W2, which satisfies: W3 ≤ W2 ≤ W3 + 5mm; the length of the fixed magnet block is denoted as L2, which satisfies: W2 ≤ L2 ≤ W2 + 5mm; the distance between the fixed magnet block and the sliding magnet groove is D4, which is 0.8mm ≤ D4 ≤ 2mm.

[0013] As a preferred technical solution, the width of the movable magnet block is W1, and the length of the movable magnet block is denoted as L1, satisfying: L2 ≤ L1 ≤ 2. L2.

[0014] As a preferred technical solution, the thickness W3 of the second magnet groove is ≥ 3.6mm.

[0015] As a preferred technical solution, the rotor laminations are made of silicon steel sheets with high magnetic permeability and low loss.

[0016] As a preferred technical solution, the magnetic pole polarity of the fixed magnet block is opposite to that of the inner end of the movable magnet block, so that the fixed magnet block generates a magnetic attraction force on the movable magnet block toward the center of the rotor.

[0017] Compared with the prior art, the movable rotor lamination topology of the drive motor provided by the present invention has the following beneficial effects:

[0018] 1. Pioneering adaptive speed movable magnet rotor topology: Breaking through the limitation of fixed magnet position in traditional permanent magnet motors, it uses centrifugal force as the driving force for high-speed magnet movement and fixed magnet as the driving force for low-speed reset, realizing adaptive adjustment of magnetic circuit characteristics with speed, fundamentally solving the contradiction of high and low speed performance, without the need for additional sensors or active control systems.

[0019] 2. High-speed expansion mechanism without additional field weakening current: As the speed increases, the movable magnet moves radially outward under centrifugal force, directly reducing the effective effect of the rotor permanent magnet flux linkage in the air gap, thereby automatically reducing the back electromotive force. This physical flux linkage attenuation directly replaces the traditional d-axis electric field weakening method, significantly reducing copper losses under high-speed conditions, improving the overall efficiency of the motor, and reducing the demand on inverter capacity.

[0020] 3. Simple and reliable structure, easy to implement in engineering: The core driving components are only centrifugal force and permanent magnet magnetic pull, without the need for complex electronic control devices, hydraulic systems or pneumatic systems, and without the need to add a large number of extra parts. The dimensions of each magnet slot and magnet are optimized and limited (such as parameters W1, D1~D4, L1, L2, etc.), ensuring the reliability and manufacturability of the sliding mechanism, low manufacturing cost, and easy mass production and application.

[0021] In addition to the purposes, features, and advantages described above, this application has other purposes, features, and advantages. A further detailed description of this application will be provided below with reference to the figures. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1 A schematic diagram of the rotor laminations of a conventional built-in permanent magnet synchronous motor with a double-V structure;

[0024] Figure 2 This is a schematic diagram showing the position of the rotor lamination magnets in the drive motor of the present invention at low speed.

[0025] Figure 3 This is a schematic diagram showing the position of the rotor lamination magnets in the drive motor of the present invention at high speed.

[0026] Figure 4 This is a detailed diagram of the movable rotor lamination topology of the drive motor of the present invention;

[0027] Figure 5 This is a comparison diagram of the output torque of the adaptive speed motor of the present invention at rated speed and at high speed.

[0028] Explanation of reference numerals in the attached drawings: 1. Rotor lamination; 2. First magnet slot; 3. Second magnet slot; 4. Sliding magnet slot; 5. Movable magnet block; 6. Fixed magnet block. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] like Figures 1-4 As shown, this invention provides a movable rotor lamination topology for a drive motor. This structure mainly includes multiple rotor laminations 1, which are coaxially stacked sequentially to form the rotor core of the motor. Each rotor lamination 1 is provided with a first magnet slot 2, a second magnet slot 3, and a sliding magnet slot 4. These magnet slots are used to place permanent magnets to generate the magnetic field required for motor operation.

[0031] In this embodiment, the rotor lamination 1 is preferably made of silicon steel sheet material with high magnetic permeability and low loss, such as 20WTG1500 or equivalent non-oriented silicon steel sheet, and is formed by precision stamping process. This can effectively reduce eddy current loss and hysteresis loss during motor operation and improve motor efficiency.

[0032] Specifically, on each rotor lamination 1, two symmetrically arranged first magnet slots 2 are distributed in a V-shape, and each first magnet is inserted into the first magnet slot 2. Similarly, two symmetrically arranged second magnet slots 3 are also distributed in a V-shape, and a second magnet is inserted into the second magnet slot 3. This double V-shaped magnet layout helps to form a multi-path magnetic circuit, optimizes the air gap magnetic flux density distribution, and thus improves the saliency ratio and reluctance torque component of the motor.

[0033] Furthermore, the sliding magnet slot 4 is positioned in the middle of a pair of second magnet slots 3. The outer end of the sliding magnet slot 4 (i.e., the end closest to the outer circumference of the rotor) is close to the inner end of the first magnet slot 2 (i.e., the end closest to the center of the rotor), while the inner end of the sliding magnet slot 4 (i.e., the end closest to the center of the rotor) is close to the inner end of the second magnet slot 3. This compact geometric layout ensures the magnetic coupling efficiency between the magnet slots and provides a smooth radial sliding channel for the movable magnet block.

[0034] The sliding magnet slot 4 is constructed as a rectangular slot extending radially, and a movable magnet block 5, capable of moving freely radially under the combined action of centrifugal force and magnetic attraction, is installed inside it. Furthermore, a third magnet slot, also rectangular in structure, is formed on the outer side of the inner end of the sliding magnet slot 4 (i.e., the side closer to the rotor center). A fixed magnet block 6 is fixedly installed in this third magnet slot, and this fixed magnet block 6 corresponds radially to the movable magnet block 5 in the sliding magnet slot 4. The magnetic pole polarity of the fixed magnet block 6 is opposite to the polarity of the inner end of the movable magnet block 5 (for example, if the N pole of the fixed magnet block 6 faces the movable magnet block 5, then the inner end of the movable magnet block 5 is the S pole), thereby generating a magnetic attraction force that pulls the movable magnet block 5 towards the rotor center.

[0035] To ensure the functional reliability and technological feasibility of the movable magnet structure, this embodiment optimizes and limits the dimensions and positional relationships of the relevant magnet slots and magnets, as follows:

[0036] 1) The width of the sliding magnet slot 4 is denoted as W1, and its thickness, along with that of the second magnet slot 3, W3, satisfies the following condition: 2mm ≤ W1 ≤ W3 + 1mm. The minimum radial distance between the inner wall of the sliding magnet slot 4 and the inner wall of the first magnet slot 2 is denoted as D1, satisfying D1 ≥ 1mm to ensure structural strength. The minimum radial distance between the inner wall of the sliding magnet slot 4 and the inner wall of the second magnet slot 3 is denoted as D2, satisfying D2 ≤ 2mm to enhance magnetic circuit coupling. The minimum circumferential (or radial) distance between the sliding magnet slot 4 and the second magnet slot 3 is denoted as D3, satisfying 0.6mm ≤ D3 ≤ 2mm. These dimensional limitations ensure sufficient mechanical strength for the rotor laminations while providing a low-friction, interference-free space for magnet sliding and ensuring effective magnetic circuit conduction.

[0037] 2) The width of the fixed magnet block 6 is denoted as W2, and its thickness W3 with that of the second magnet groove 3 satisfies: W3 ≤ W2 ≤ W3 + 5mm; the length of the fixed magnet block 6 is denoted as L2, satisfying: W2 ≤ L2 ≤ W2 + 5mm. The minimum distance between the fixed magnet block 6 and the sliding magnet groove 4 is denoted as D4, satisfying 0.8mm ≤ D4 ≤ 2mm. This dimensional setting ensures, on the one hand, that the fixed magnet groove has sufficient space to accommodate the permanent magnet that generates suitable magnetic attraction, and on the other hand, by controlling the distance D4, ensures that the movable magnet block 5 can be reliably attracted by the magnetic force of the fixed magnet block 6 and held in the reset position (i.e., the inner side of the sliding magnet groove 4) when the rotation speed is low and the centrifugal force is small. Figure 2 The low-speed position is shown.

[0038] 3) The width of the movable magnet block 5 is consistent with the width W1 of the sliding magnet groove 4 to ensure a sliding fit. The length of the movable magnet block 5 is denoted as L1, satisfying: L2 ≤ L1 ≤ 2 L2. This size range ensures that the movable magnet 5 has a moderate mass, which can respond sensitively to centrifugal force while ensuring its mechanical strength and manufacturability, and avoiding breakage or jamming during high-speed sliding.

[0039] 4) The thickness (i.e. its radial dimension) of the second magnet groove 3 is denoted as W3, which satisfies W3 ≥ 3.6mm to ensure that the second magnet has sufficient magnetic flux cross-sectional area, thereby providing sufficient permanent magnet flux linkage.

[0040] The working principle and process of the movable rotor lamination topology of the drive motor of the present invention are briefly described below.

[0041] When the motor is in a low-speed, high-torque operating condition (such as...) Figure 2As shown in the diagram, the rotor speed is relatively low, and the centrifugal force on the movable magnet block 5 is small. At this time, the magnetic attraction of the fixed magnet block 6 to the movable magnet block 5 is dominant, firmly adhering the movable magnet block 5 to the inner side of the sliding magnet slot 4 (near the center of the rotor). In this position, the movable magnet block 5, the first magnet, and the second magnet together contribute the maximum permanent magnet flux linkage, enabling the motor to output a large torque.

[0042] When the motor speed increases to high-speed operating conditions (such as...) Figure 3 As shown in the diagram, the centrifugal force on the movable magnet 5 increases sharply in proportion to the square of the rotational speed. When the centrifugal force exceeds the magnetic attraction force of the fixed magnet 6, the movable magnet 5 will move radially outward (i.e., away from the rotor center) along the sliding magnet groove 4 until it abuts against the outer end of the sliding magnet groove 4. As the movable magnet 5 moves outward, the effective effect of the magnetic field it generates in the air gap weakens, resulting in a significant reduction in the total rotor permanent magnet flux linkage.

[0043] Combination Figure 5 As shown: This figure compares the output torque of the adaptive speed motor designed in this scheme at rated speed (magnets on the inside) and high speed (magnets on the outside). From Figure 5 It is clearly evident that at high speeds, the output torque of the motor decreases significantly as the movable magnet block 5 moves to a more outer position. This clearly demonstrates that the rotor permanent magnet flux linkage automatically decreases due to the radial displacement of the magnets. This physical flux linkage attenuation directly replaces the d-axis field-weakening current required by traditional motors, thereby significantly reducing copper losses at high speeds and improving motor efficiency. Simultaneously, because the back electromotive force is effectively suppressed, the motor does not require a large-capacity field-weakening current from the inverter, reducing system costs.

[0044] In summary, by setting a radially sliding magnetic block, the present invention utilizes the balance between centrifugal force and magnetic pull to achieve adaptive adjustment of the motor's magnetic circuit characteristics to the rotational speed, fundamentally resolving the contradiction between the low-speed, high-torque requirements and the high-speed, field-weakening, speed-enhancing requirements of permanent magnet synchronous motors.

[0045] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A movable rotor lamination topology for a drive motor, characterized in that, include: Multiple rotor laminations (1) are arranged coaxially in sequence; each rotor lamination (1) is provided with a first magnet slot (2), a second magnet slot (3) and a sliding magnet slot (4). Two symmetrically arranged first magnet slots (2) are distributed in a V-shape, and a first magnet is inserted inside the first magnet slot (2); two symmetrically arranged second magnet slots (3) are distributed in a V-shape, and a second magnet is inserted inside the second magnet slot (3). The sliding magnet groove (4) is located in the middle of a pair of second magnet grooves (3). The outer end of the sliding magnet groove (4) is close to the inner end of the first magnet groove (2), and the inner end of the sliding magnet groove (4) is close to the inner end of the second magnet groove (3). The sliding magnet groove (4) is a rectangular groove, and a movable magnet block (5) that can move radially is installed inside it. The inner end of the sliding magnetic steel groove (4) also has a third magnetic steel groove. The third magnetic steel groove is a rectangular structure, and a fixed magnetic steel block (6) is fixedly installed inside it. The fixed magnetic steel block (6) corresponds to the movable magnetic steel block (5) inside the sliding magnetic steel groove (4).

2. The movable rotor lamination topology of the drive motor according to claim 1, characterized in that, The width of the sliding magnet groove (4) is denoted as W1, and the thickness of the second magnet groove (3) is denoted as W3, satisfying: 2mm ≤ W1 ≤ W3 +1mm.

3. The movable rotor lamination topology of the drive motor according to claim 2, characterized in that, The distance between the sliding magnet groove (4) and the inner side of the first magnet groove (2) is D1, where D1 ≥ 1mm; the distance between the sliding magnet groove (4) and the inner side of the second magnet groove (3) is D2, where D2 ≤ 2mm; the distance between the sliding magnet groove (4) and the second magnet groove (3) is D3, where 0.6mm ≤ D3 ≤ 2mm.

4. The movable rotor lamination topology of the drive motor according to claim 2, characterized in that, The width of the fixed magnet block (6) is denoted as W2, which satisfies: W3 ≤ W2 ≤ W3 + 5mm.

5. The movable rotor lamination topology of the drive motor according to claim 4, characterized in that, The length of the fixed magnet block (6) is denoted as L2, which satisfies: W2 ≤ L2 ≤ W2 + 5mm; the distance between the fixed magnet block (6) and the sliding magnet groove (4) is D4, which is 0.8mm ≤ D4 ≤ 2mm.

6. The movable rotor lamination topology of the drive motor according to claim 5, characterized in that, The width of the movable magnetic block (5) is W1, and the length of the movable magnetic block (5) is denoted as L1, satisfying: L2 ≤ L1 ≤ 2. L2.

7. The movable rotor lamination topology of the drive motor according to claim 2, characterized in that, The thickness W3 of the second magnet groove (3) is ≥ 3.6mm.

8. The movable rotor lamination topology of the drive motor according to claim 1, characterized in that, The rotor lamination (1) is made of silicon steel sheet with high magnetic permeability and low loss.

9. The movable rotor lamination topology of the drive motor according to claim 1, characterized in that, The magnetic pole polarity of the fixed magnet block (6) is opposite to that of the inner end of the movable magnet block (5), so that the fixed magnet block (6) generates a magnetic attraction force on the movable magnet block (5) toward the center of the rotor.

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