Three-coil E-type electromagnetic actuator and optimization method thereof

Abstract

The invention discloses a three-coil E-type electromagnetic actuator and an optimization method thereof. The actuator comprises a stator assembly and a rotor assembly. A central column of an E-shaped magnetic cylinder of the rotor assembly is arranged outside a stator shaft in a sleeving mode and is in sliding connection with the stator shaft through a bearing bush and a linear bearing. The upper permanent magnet and the lower permanent magnet are fixed to the inner sides of an upper side arm and a lower side arm of the E-shaped magnetic cylinder respectively, the upper magnet yoke is connected to the outer side of the upper permanent magnet, the lower magnet yoke is connected to the outer side of the lower permanent magnet, and the middle magnet yoke is connected between the upper permanent magnet and the lower permanent magnet. The three groups of coils comprise two groups of end coils and a group of middle coils, the two groups of end coils are respectively positioned in two air gaps formed between the E-shaped magnetic cylinder and the upper magnet yoke and between the E-shaped magnetic cylinder and the lower magnet yoke, and the middle coils are positioned in a central air gap formed between a central column of the E-shaped magnetic cylinder and the middle magnet yoke; the winding directions of the two groups of end coils are the same, and the winding direction of the middle coil is opposite to that of the end coils; the compression spring is arranged between the rotor assembly and the stator assembly.

Description

Technical Field

[0001] This invention relates to the field of active vibration control technology, specifically to a three-coil E-type electromagnetic actuator with high coil frame utilization and high power density for low-frequency and ultra-low-frequency vibration control, and its structural optimization method. Background Technology In fields such as vehicles, ships, and aerospace, traditional passive vibration isolation or vibration absorbers are limited by narrow bandwidth and low efficiency, making it difficult to meet the increasingly high requirements of various instruments and equipment for vibration control. Active vibration control reduces vibration response by using control algorithms to drive actuators to apply control forces to the controlled object.

[0002] An electromagnetic actuator is an active execution mechanism based on electromagnetic force. Its principle is to adjust the active control force by controlling the magnitude and frequency of the current in the coil winding. Based on the different magnetic field formation mechanisms of the main magnetic circuit, electromagnetic actuators can be divided into permanent magnet type and excitation type. The permanent magnet type uses permanent magnets to form the main magnetic circuit, while the excitation type uses an excitation coil and a magnetic conductor to form the main magnetic circuit. Electromagnetic actuators are widely used in many fields due to their advantages such as fast response speed, high force-current linearity, and large control force.

[0003] Currently, electromagnetic actuators generally suffer from problems such as low coil frame utilization, low effective coil length, and unreasonable magnetic circuit design.

[0004] In existing related patented technologies, such as the magnetic levitation actuator described in CN117498722A, the coil assembly is typically a single coil structure with a limited effective length. Within the limited installation space, a large number of coil wires are located in the non-working air gap region, failing to effectively participate in electromagnetic force generation, leading to material waste and increased heat loss. To achieve three-degree-of-freedom control, a complex structure with three independent actuators orthogonally arranged is adopted, resulting in a large volume, difficulty in center-of-mass matching, and room for improvement in the performance of each actuator itself. Other single-degree-of-freedom actuators cannot meet the requirements of multi-directional vibration coupling control. For example, the high-power-density actuator described in CN117040226A, although using ring and L-shaped magnetic conductors to construct the magnetic circuit, is essentially still a single magnetic loop structure. When pursuing high magnetic field strength, a single magnetic circuit easily reaches local magnetic saturation (e.g., the saturation magnetic flux density of DT4C soft magnetic material is approximately 2.45T), limiting further increases in output force and resulting in significant magnetic leakage, reducing magnetic energy utilization efficiency.

[0005] Therefore, there is an urgent need for a new type of electromagnetic actuator and its optimization method, which can significantly improve the effective utilization rate of the coil and the air gap magnetic field strength while ensuring a compact structure, thereby achieving higher output density and lower energy consumption, so as to better serve the field of active control of low-frequency vibration. Summary of the Invention The purpose of this invention is to overcome the shortcomings of existing technologies and provide a three-coil E-type electromagnetic actuator with high coil utilization and its optimization method. This actuator maximizes the use of coil frame space through an innovative E-type magnetic cylinder and three-coil layout, and constructs a dual magnetic circuit to alleviate magnetic saturation and reduce magnetic leakage, ultimately achieving high power density and high-efficiency electromagnetic force output. This actuator has higher coil frame utilization and effective coil length. Furthermore, an optimization algorithm is used to optimize the structure of the actuator's magnetic field circuit, reducing circuit magnetic leakage while increasing the magnetic field strength at the air gap, thereby achieving a higher output force density.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A three-coil E-type electromagnetic actuator includes a stator assembly and a mover assembly. The stator assembly includes a stator shaft, a coil frame fixed to a base plate, and three sets of coils wound on the coil frame. The mover assembly includes an upper top plate, an E-type magnetic cylinder, an upper permanent magnet, a lower permanent magnet, an upper yoke, a middle yoke, a lower yoke, a compression spring, a bearing bushing, and a linear bearing. The central column of the E-type magnetic cylinder is sleeved outside the stator shaft and forms a sliding connection with the stator shaft through the bearing bushing and the linear bearing. The upper and lower permanent magnets are respectively fixed to the inner sides of the upper and lower side arms of the E-type magnetic cylinder, wherein the upper surface of the upper permanent magnet is the N pole and the lower surface is the S pole. The lower surface of the permanent magnet is the N pole, and the upper surface is the S pole; the upper yoke is connected to the outside of the upper permanent magnet, the lower yoke is connected to the outside of the lower permanent magnet, and the middle yoke is connected between the upper and lower permanent magnets; the three sets of coils include two sets of end coils and one set of middle coils. The two sets of end coils are respectively located in the two air gaps formed by the E-type magnetic cylinder and the upper yoke, and the E-type magnetic cylinder and the lower yoke. The middle coil is located in the central air gap formed by the central column of the E-type magnetic cylinder and the middle yoke; the two sets of end coils are wound in the same direction, and the winding direction of the middle coil is opposite to that of the end coils; the compression spring is disposed between the mover assembly and the stator assembly. Furthermore, the upper and lower permanent magnets are made of neodymium iron boron (NdFeB) permanent magnet material. Furthermore, the upper yoke, lower yoke, and middle yoke are made of DT4C soft magnetic material. Furthermore, the E-type magnetic cylinder, together with the upper and lower magnetic yokes, forms two parallel main magnetic circuits to disperse the magnetic flux and prevent magnetic circuit saturation. Furthermore, the axial length of the coil frame is completely covered by three sets of coils, and the utilization rate of the coil frame is over 90%. Furthermore, the moving part assembly also includes a limiting ring, which is disposed between the lower magnetic yoke and the bearing bushing to limit the relative movement of the upper, middle and lower magnetic yokes and the upper and lower permanent magnets. Furthermore, the two ends of the stator shaft are connected to the top plate and the bottom plate by bolts to form a stable stator frame. A method for optimizing the aforementioned three-coil E-type electromagnetic actuator includes the following steps: S1: Establishing a finite element analysis model of the actuator's electromagnetic field; S2: Selecting the key geometric dimensions of the E-type magnetic cylinder as optimization variables; S3: Setting the optimization objective as maximizing the average magnetic field strength (Bq) at all air gaps, with the constraint that the maximum magnetic flux density (Bs) of all magnetically conductive components does not exceed the saturation magnetic flux density of their materials; S4: Using a genetic algorithm to iteratively optimize the optimization variables until the fitness function converges, outputting the optimal magnetic circuit structure parameters. Furthermore, the optimization variables include the thickness of the center column of the E-type magnetic cylinder, the thickness of the two side arms, the height of each part, and the total width. Furthermore, in step S4, a genetic algorithm is used to optimize the parameters as follows: There are 8 structural parameters, including D. The specific optimization model is as follows:

[0007] in, Represents the design domain. Fitness Representative fitness evaluation index, This represents the magnetic field strength at the air gap. This represents the saturation magnetic flux density of the magnetic circuit.

[0008] Compared with the prior art, the present invention has the following significant advantages: 1. High coil frame utilization: By arranging coils in all three air gaps (two end air gaps and one center air gap) of the E-type magnetic cylinder, the entire axial length of the coil frame is fully utilized, significantly improving the effective length of the coil and avoiding the problems of low coil frame utilization or insufficient effective wire length in traditional single-coil structures.

[0009] 2. High electromagnetic force output: Based on the electromagnetic force formula With a fixed number of turns N and current i, the air gap magnetic induction intensity can be increased by increasing the effective length L and optimizing the magnetic circuit. Under the dual action, it can obtain electromagnetic force output that is much higher than that of traditional structures.

[0010] 3. High-efficiency magnetic circuit design: The E-type magnetic cylinder and the upper and lower permanent magnets together form two parallel main magnetic circuits (upper circuit and lower circuit). This dual-circuit design effectively disperses the magnetic flux, avoiding the problem of single circuit saturation under high magnetic fields. At the same time, the compact E-type structure also reduces magnetic leakage in the magnetic circuit and improves the efficiency of magnetic energy utilization.

[0011] 4. Compact structure and high power density: By integrating three coils into one E-type magnetic cylinder, the present invention has a compact structure, small size and light weight, while having high output force and achieving high power density.

[0012] 5. Optimized design ensures performance: By using a multi-parameter optimization method based on genetic algorithms, the structural dimensions that maximize the air gap magnetic field strength can be accurately found without causing magnetic circuit saturation, thus ensuring the optimal performance of the actuator. Attached Figure Description Figure 1 This is a schematic diagram of the structure of the three-coil E-type electromagnetic actuator of the present invention; Figure 2 This is a schematic diagram of the magnetic field circuit of the three-coil E-type electromagnetic actuator of the present invention; Figure 3 This is a flowchart of the magnetic circuit structure optimization method of the present invention; Explanation of reference numerals in the attached diagram: 1. Bolt; 2. Top plate; 3. Type E magnetic cylinder; 4. Coil; 5. Coil frame; 6. Base plate; 7. Upper yoke; 8. Upper permanent magnet; 9. Middle yoke; 10. Lower permanent magnet; 11. Lower yoke; 12. Limiting ring; 13. Compression spring; 14. Stator shaft; 15. Bearing bushing; 16. Linear bearing. Detailed Implementation The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. This invention proposes a novel three-coil E-type electromagnetic actuator. Using a permanent magnet and a magnetically conductive material as the main magnetic circuit, the winding coils are generally perpendicular to the magnetic circuit direction constructed by the permanent magnet to enhance the output electromagnetic force. The Ampere force experienced by the coils is...

[0013] In the formula, Represents the output electromagnetic force. N Represents the number of coil windings. It is the magnetic field strength at the air gap. i For coil current, L This refers to the effective length of the coil. Therefore, when the number of coil windings and the current magnitude are fixed, in order to increase the magnitude of the output electromagnetic force, it is necessary to increase the effective length of the coil and the magnetic field strength at the air gap.

[0014] like Figure 1As shown, a novel three-coil E-type electromagnetic actuator of the present invention comprises the following components: bolt 1, upper top plate 2, E-type magnetic cylinder 3, coil 4, coil frame 5, base plate 6, upper yoke 7, upper permanent magnet 8, middle yoke 9, lower permanent magnet 10, lower yoke 11, limiting ring 12, compression spring 13, stator shaft 14, bearing bushing 15, and linear bearing 16. The upper and lower permanent magnets 8 and 10 are made of NdFeB, while the upper yoke 7, middle yoke 9, and lower yoke 11 are made of DT4C soft magnetic material, which has good magnetic permeability and a saturation magnetic flux density of approximately 2.45T. The remaining components are made of non-magnetic materials. The mover assembly mainly includes: upper top plate 2, E-type magnetic cylinder 3, upper permanent magnet 8, lower permanent magnet 10, upper magnetic yoke 7, middle magnetic yoke 9, lower magnetic yoke 11, bearing bushing 15, linear bearing 16, and compression spring 13; the stator assembly mainly includes: stator shaft 14, coil 4, and coil frame 5.

[0015] The central column of the E-type magnetic cylinder 3 is sleeved outside the stator shaft 14 and is slidably connected to the stator shaft 14 through the bearing bushing 15 and the linear bearing 16. The upper permanent magnet 8 and the lower permanent magnet 10 are respectively fixed to the inner sides of the upper and lower side arms of the E-type magnetic cylinder 3. The upper surface of the upper permanent magnet 8 is the N pole and the lower surface is the S pole, and the lower surface of the lower permanent magnet 10 is the N pole and the upper surface is the S pole. The upper yoke 7 is connected to the outside of the upper permanent magnet 8, the lower yoke 11 is connected to the outside of the lower permanent magnet 10, and the middle yoke 9 is connected between the upper permanent magnet 8 and the lower permanent magnet 10. The three sets of coils 4 include two sets of end coils and one set of middle coils. The two sets of end coils are located on the E-type magnetic cylinder 3 and the upper yoke 7, respectively. The middle coil is located in the central air gap formed by the E-type magnetic cylinder 3 and the lower magnetic yoke 11 in the two air gaps; the winding direction of the two sets of end coils is the same; the winding direction of the middle coil is opposite to that of the end coils; the compression spring 13 is set between the mover assembly and the stator assembly to provide the mover with a reset elastic force. A novel three-coil E-type electromagnetic actuator magnetic field circuit, such as Figure 2 As shown, the upper surface of the upper permanent magnet is N-pole and the lower surface is S-pole, while the lower surface of the lower permanent magnet is N-pole and the upper surface is S-pole. The magnetic field lines of both the upper and lower permanent magnets originate from the N-pole, pass through the upper and lower yokes respectively, through the air gap, through the upper and lower coils respectively, then through the E-type magnetic cylinder, through the air gap again, through the middle coil, and finally return to the S-pole of the upper and lower permanent magnets via the middle yoke. When an alternating current of a specific frequency is applied to the coils, according to Ampere's law, an electromagnetic force of the corresponding frequency is generated, thereby driving the actuator assembly to reciprocate up and down. Because the magnetic field lines passing through the three coils have different orientations, the upper and lower coils have the same winding direction, while the middle coil winding adopts the opposite winding direction to the upper and lower coils.

[0016] This invention proposes a novel three-coil E-type electromagnetic actuator and its optimization method. To effectively enhance the electromagnetic force output by the actuator, the magnetic circuit structure needs to be optimized. Since the saturation magnetic flux density of the magnetic material DT4C is approximately 2.45T, the optimization objective is to maximize the magnetic field strength at the air gap while ensuring that the magnetic flux density of the magnetic material does not saturate. The optimization method employs a genetic algorithm, with the following optimization parameters: And D, a total of 8 structural parameters, the optimization flowchart is as follows Figure 3 As shown, the specific optimization model is as follows:

[0017] in, Represents the design domain. Fitness Representative fitness evaluation index, This represents the magnetic field strength at the air gap. This represents the magnetic flux density of the magnetic circuit.

[0018] The present invention has the following advantages: (1) The three-coil configuration has a higher utilization rate of the coil frame; (2) The three-coil configuration can increase the effective length of the coil, thereby outputting a larger electromagnetic force under the same conditions; (3) The designed E-type magnetic cylinder has a more compact structure and can form two magnetic circuits, which can effectively alleviate the phenomenon of easy magnetic saturation of a single circuit. (4) The novel three-coil E-type electromagnetic actuator designed can effectively improve the magnetic field strength at the air gap while reducing magnetic leakage in the magnetic circuit after optimization by the optimization algorithm.

Claims

1. A three-coil E-type electromagnetic actuator, characterized in that, The system includes a stator assembly and a mover assembly. The stator assembly includes a stator shaft, a coil frame fixed to a base plate, and three sets of coils wound on the coil frame. The mover assembly includes an upper top plate, an E-type magnetic cylinder, an upper permanent magnet, a lower permanent magnet, an upper yoke, a middle yoke, a lower yoke, a compression spring, a bearing bushing, and a linear bearing. The central column of the E-type magnetic cylinder is sleeved outside the stator shaft and forms a sliding connection with the stator shaft through the bearing bushing and the linear bearing. The upper and lower permanent magnets are respectively fixed to the inner sides of the upper and lower side arms of the E-type magnetic cylinder. The upper surface of the upper permanent magnet is the N pole, and the lower surface is the S pole. The upper surface is the N pole, and the lower surface is the S pole. The upper yoke is connected to the outside of the upper permanent magnet, the lower yoke is connected to the outside of the lower permanent magnet, and the middle yoke is connected between the upper and lower permanent magnets. The three sets of coils include two sets of end coils and one set of middle coils. The two sets of end coils are located in the two air gaps formed by the E-type magnetic cylinder and the upper yoke, and the E-type magnetic cylinder and the lower yoke, respectively. The middle coil is located in the central air gap formed by the central column of the E-type magnetic cylinder and the middle yoke. The two sets of end coils are wound in the same direction, and the winding direction of the middle coil is opposite to that of the end coils. The compression spring is located between the mover assembly and the stator assembly.

2. The three-coil E-type electromagnetic actuator according to claim 1, characterized in that, The upper and lower permanent magnets are made of neodymium iron boron (NdFeB) permanent magnet material.

3. The three-coil E-type electromagnetic actuator according to claim 1, characterized in that, The upper yoke, lower yoke, and middle yoke are made of DT4C soft magnetic material.

4. The three-coil E-type electromagnetic actuator according to claim 1, characterized in that, The E-type magnetic cylinder, together with the upper and lower magnetic yokes, forms two parallel main magnetic circuits, which are used to disperse the magnetic flux and prevent magnetic circuit saturation.

5. The three-coil E-type electromagnetic actuator according to claim 1, characterized in that, The axial length of the coil frame is completely covered by three sets of coils, and the utilization rate of the coil frame is over 90%.

6. The three-coil E-type electromagnetic actuator according to claim 1, characterized in that, The moving part assembly also includes a limiting ring, which is disposed between the lower magnetic yoke and the bearing bushing to limit the relative movement of the upper, middle and lower magnetic yokes and the upper and lower permanent magnets.

7. The three-coil E-type electromagnetic actuator according to claim 1, characterized in that, The two ends of the stator shaft are connected to the top plate and the bottom plate by bolts to form a stable stator frame.

8. A method for optimizing the three-coil E-type electromagnetic actuator as described in any one of claims 1-7, characterized in that, The process includes the following steps: S1: Establish an electromagnetic field finite element analysis model of the actuator; S2: Select the key geometric dimensions of the E-type magnetic cylinder as optimization variables; S3: Set the optimization objective to maximize the average magnetic field strength (Bq) at all air gaps, with the constraint that the maximum magnetic flux density (Bs) of all magnetically conductive components does not exceed the saturation magnetic flux density of their materials; S4: Use a genetic algorithm to iteratively optimize the optimization variables until the fitness function converges, and output the optimal magnetic circuit structure parameters.

9. The method according to claim 8, characterized in that, The optimization variables include the thickness of the center column of the E-type magnetic cylinder, the thickness of both side arms, the height of each part, and the total width.

10. The method according to claim 8, characterized in that, In step S4, a genetic algorithm is used to optimize the parameters as follows: There are 8 structural parameters, including D. The specific optimization model is as follows: in, Represents the design domain. Fitness Represents fitness evaluation indicators, This represents the magnetic field strength at the air gap. This represents the magnetic flux density of the magnetic circuit.

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