Optimization method and system for pole-slot combination of bidirectional modulation permanent magnet vernier motor

Abstract

This invention relates to a method and system for optimizing pole-slot matching in a bidirectional modulated permanent magnet vernier motor, belonging to the field of permanent magnet motor design technology. The invention aims to solve the problems of low output torque, high harmonic content, and large torque pulsation in bidirectional modulated permanent magnet vernier motors caused by unreasonable pole-slot matching. The method includes: establishing a complete magnetic field analysis model encompassing air gap permeability, permanent magnet magnetomotive force, armature magnetomotive force, and air gap magnetic flux density; analyzing the harmonic components of the permanent magnet magnetic field and the armature magnetic field, identifying the stationary harmonic magnetic fields generated by the stator permanent magnet, ensuring that at least one stationary harmonic magnetic field in the armature magnetic field has a pole pair number equal to the stator permanent magnet pole pair number; establishing constraints, with the pole-slot matching selection principle satisfying one of six equations; and combining this with the engineering constraint that the winding factor is not less than 0.9 to screen and verify the optimal solution.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor design technology, and in particular to a method and system for optimizing pole-slot matching of a bidirectional modulated permanent magnet vernier motor, which aims to improve the motor torque output performance by optimizing pole-slot matching. Background Technology

[0002] Permanent magnet vernier motors are a new type of special motor that operates based on the principle of magnetic field modulation. They typically employ a "single-sided permanent magnet" structure, where the permanent magnet is placed only on one side of the rotor, while the stator core and armature windings are on the other side. This single-sided structure utilizes the modulation effect generated by stator slotting to synchronously interact the stator armature magnetic field harmonics with the rotor permanent magnet magnetic field, achieving "low-speed, high-torque" and "direct-drive" operating characteristics. This makes them ideal for direct-drive applications requiring high torque density, high efficiency, and no reduction gear, such as electric vehicles, wind power generation, servo drives, and aerospace. Compared to traditional permanent magnet synchronous motors, permanent magnet vernier motors can output higher torque within the same volume, demonstrating significant application potential.

[0003] To further enhance the torque output capability of the motor, permanent magnets are placed at the stator slots based on the existing structure, changing the "N-pole-S-pole" structure of the rotor permanent magnets to an "N-pole-iron-pole" structure. This achieves bidirectional modulation of the stator and rotor permanent magnet magnetic fields, thereby outputting greater torque. However, improper selection of pole-slot combinations can prevent the stator permanent magnet harmonic magnetic field and the armature harmonic magnetic field from effectively coupling, resulting in a lower-than-expected output torque. This renders the cost and material investment in the bilateral permanent magnet structure meaningless, and the torque density cannot be improved. Furthermore, improper combinations often excite a large number of non-operating subharmonics. The interaction of these harmonics exacerbates torque ripple. This not only leads to unstable motor operation and affects control accuracy but also generates additional vibration and electromagnetic noise, making the motor unsuitable for applications requiring high stability. Therefore, selecting a reasonable pole-slot combination scheme is crucial for bidirectional modulated permanent magnet vernier motors. Summary of the Invention

[0004] To address the issues of low output torque, high harmonic content, and large torque pulsation in bidirectional modulated permanent magnet vernier motors caused by improper pole-slot matching, this invention provides a method for optimizing the pole-slot matching of bidirectional modulated permanent magnet vernier motors.

[0005] In one aspect, the present invention provides a method for optimizing the pole-slot fit of the bidirectional modulated permanent magnet vernier motor, comprising the following steps:

[0006] S1. Establish a magnetic field analysis model for the motor;

[0007] S2. Analyze the harmonic components of the permanent magnet magnetic field and the armature magnetic field, and obtain the number of pole pairs and rotational speed characteristics of each harmonic.

[0008] S3. Identify the stationary harmonic magnetic field generated by the stator permanent magnet. At least one stationary harmonic magnetic field exists in the armature magnetic field; the number of pole pairs is equal to the number of pole pairs of the stator permanent magnet. ;

[0009] S4. Establish constraints:

[0010] When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations:

[0011]

[0012]

[0013]

[0014] When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations:

[0015]

[0016]

[0017]

[0018] In the formula, This represents the harmonic order of the armature magnetomotive force. For intermediate parameters, ; The harmonic order of the air gap ratio permeability considering only the effect of stator tooth spacing variation. ; This represents the number of pole pairs of the rotor permanent magnet. The number of repeating units of the phase winding magnetomotive force in one mechanical cycle;

[0019] S5. Combining the winding factor constraint, select candidate pole-slot matching schemes that meet the above conditions.

[0020] Preferably, in step S1, the magnetic field analysis model of the motor includes the air gap ratio magnetic permeability model, the permanent magnet magnetomotive force model, the armature magnetomotive force model, the permanent magnet magnetic field air gap magnetic flux density model, and the armature magnetic field air gap magnetic flux density model.

[0021] Preferably, the winding factor constraint in step S5 is: the fundamental winding factor of the motor is not less than 0.9.

[0022] Preferably, the method is applicable to bidirectional modulation single-rotor permanent magnet vernier motors, bidirectional modulation dual-rotor permanent magnet vernier motors, and bidirectional modulation dual-stator permanent magnet vernier motors.

[0023] In another aspect, the present invention provides a pole-slot matching optimization system for the bidirectional modulated permanent magnet vernier motor, comprising:

[0024] The magnetic field modeling module is used to establish the magnetic field analysis model of the motor.

[0025] The harmonic analysis module is used to analyze the harmonic components of the permanent magnet magnetic field and the armature magnetic field;

[0026] The condition matching module sets a set of pole slot mating conditions, the condition set including:

[0027] When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations:

[0028]

[0029]

[0030]

[0031] When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations:

[0032]

[0033]

[0034]

[0035] In the formula, This represents the harmonic order of the armature magnetomotive force. For intermediate parameters, ; The harmonic order of the air gap ratio permeability considering only the effect of stator tooth spacing variation. ; This represents the number of pole pairs of the rotor permanent magnet. The number of repeating units of the phase winding magnetomotive force in one mechanical cycle;

[0036] The scheme selection module is used to select candidate schemes that meet the conditions based on the winding factor constraints.

[0037] The result output module is used to output the optimized pole slot matching scheme.

[0038] Preferably, the system further includes a database module for storing typical pole-slot mating schemes and harmonic characteristic data.

[0039] The beneficial effects of the present invention are as follows: By selecting specific pole slot combinations, the present invention can increase the effective harmonic content of the permanent magnet magnetic field and the armature magnetic field, ensuring that the main working harmonics are fully utilized to output higher torque, thereby significantly improving the torque density of the motor.

[0040] This invention provides a clear and explicit set of pole-slot matching selection principles for bidirectional modulated permanent magnet vernier motors. These principles guide designers to quickly and accurately determine the optimal pole-slot matching scheme for this type of motor, significantly shortening the development cycle, reducing design costs and risks, and laying a crucial theoretical foundation for the industrialization and promotion of this type of motor. Attached Figure Description

[0041] Figure 1 This is a structural diagram of the bidirectional modulation permanent magnet vernier motor described in this invention;

[0042] Figure 2 This is a comparison diagram of the torque waveforms of the motor under the three pole-slot matching schemes described in this invention;

[0043] Figure 3 This is a flowchart of the method of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0047] Specific Implementation Method 1: The following is combined with... Figures 1 to 3 This embodiment describes the pole-slot matching optimization method for the bidirectional modulated permanent magnet vernier motor. See [link to relevant documentation]. Figure 3 ,include:

[0048] Step S1: Establish the magnetic field analysis model of the motor; the magnetic field analysis model of the motor includes five core sub-models: air gap ratio magnetic permeability model, permanent magnet magnetomotive force model, armature magnetomotive force model, permanent magnet magnetic field air gap magnetic flux density model, and armature magnetic field air gap magnetic flux density model.

[0049] (1) Air gap ratio permeability model

[0050] Taking into account the dual modulation effect of stator and rotor tooth slots, its unified expression is:

[0051]

[0052] In the formula, For air gap ratio permeability, This is the air gap length; Permeability of free space; Spatial location; For time; For the air gap ratio permeability considering only the effect of stator tooth space variation, in the formula... and These are the constants of the air gap ratio permeability considering only the effect of stator tooth cogging variation, and Second harmonic amplitude; This refers to the number of stator slots; For the air gap ratio permeability considering only the effect of rotor tooth cogging variation, in the formula... and These are the constants of the air gap ratio permeability considering only the variation in rotor tooth cogging, and... Second harmonic amplitude; The number of pole pairs of the rotor permanent magnet; This is the initial position of the rotor; The angular velocity of the permanent magnet rotor. It is the harmonic order of the air gap ratio permeability considering only the effect of stator tooth groove variation.

[0053] (2) Permanent magnet magnetomotive force model

[0054] This model incorporates the magnetomotive force generated by the stator permanent magnet and the rotor permanent magnet:

[0055] Rotor permanent magnet magnetomotive force expression:

[0056]

[0057] Stator permanent magnet magnetomotive force expression:

[0058]

[0059] In the formula, This represents the DC component of the rotor magnetomotive force. Rotor magnetomotive force Second harmonic amplitude; This is the DC component of the stator magnetomotive force; stator magnetomotive force Second harmonic amplitude.

[0060] (3) Armature magnetomotive force model

[0061]

[0062] In the formula, armature magnetomotive force Second harmonic amplitude; The number of repeating units of the phase winding magnetomotive force in one mechanical cycle, where . The meaning is the harmonic order of the armature magnetomotive force.

[0063] (4) Permanent magnet magnetic field air gap magnetic flux density model

[0064] The total magnetic field generated by the permanent magnet is obtained by modulating the permanent magnet magnetomotive force with the air gap ratio permeability, thus obtaining the permanent magnet magnetic field air gap magnetic flux density. :

[0065]

[0066] (5) Armature magnetic field air gap magnetic flux density model

[0067] The magnetic field generated by the armature current is obtained by modulating the armature magnetomotive force with the air gap ratio permeability, thus obtaining the armature magnetic field air gap magnetic flux density. :

[0068]

[0069] The above five models together form the theoretical basis for the magnetic field and harmonic analysis of this invention. By combining them, the spatiotemporal distribution of all magnetic fields in the air gap and their harmonic composition can be systematically analyzed, providing an accurate mathematical basis for subsequent pole-slot matching optimization.

[0070] Step S2: Harmonic Analysis and Key Harmonic Identification

[0071] The model established in step S1 is subjected to Fourier series expansion and product operation to analyze the harmonic components of the magnetic field.

[0072] Analyzing the harmonic characteristics of the air gap magnetic flux density of the permanent magnet magnetic field, when When all values ​​are 1, the amplitude of each harmonic of the permanent magnet magnetic field is at its maximum. The corresponding harmonic pole pairs and speed are shown in Table 1 below. Traditional rotor permanent magnet vernier motors only have... and Two effective sub-harmonics exist in this type of stator-rotor dual-sided permanent magnet motor, resulting in a static state. For polar harmonic magnetic fields, if it is possible to By utilizing the polar harmonic magnetic field, the torque output capability of the motor can be significantly improved.

[0073] Table 1 Harmonic Characteristics of Air Gap Magnetic Dense in Permanent Magnet Magnetic Field

[0074]

[0075] The harmonic characteristics of the air gap magnetic flux density of the armature magnetic field are analyzed, and the corresponding harmonic pole pairs and rotational speeds are shown in Table 2 below.

[0076] Table 2 Harmonic Characteristics of Armature Magnetic Field Air Gap Magnetic Dense

[0077]

[0078] As shown in the chart, only when When the value is 1, a stationary magnetic field exists in the armature magnetic field. At this time, the number of harmonic pole pairs of the stationary magnetic field in the armature magnetic field includes six types. Only when at least one of the following harmonic pole pairs of the stationary magnetic field is equal to the number of stator permanent magnet pole pairs can a stationary magnetic field exist. Only static harmonic magnetic fields can be used to generate torque.

[0079] Step S3: Determine the armature winding phase type and apply the corresponding pole-slot matching conditions, as shown in Table 3.

[0080] Table 3. Selection Principles for Pole-Slot Matching of Bidirectional Modulated Permanent Magnet Vernier Motor

[0081]

[0082] In the formula, This represents the harmonic order of the armature magnetomotive force. For intermediate parameters, ; The harmonic order of the air gap ratio permeability considering only the effect of stator tooth spacing variation. ; This represents the number of pole pairs of the rotor permanent magnet. This represents the number of repeating units of the phase winding magnetomotive force in one mechanical cycle.

[0083] The following example illustrates the selection principle for pole slot matching in a bidirectional modulated permanent magnet vernier motor, based on the number of stator slots. Taking 24 as an example, with the goal of improving motor torque, the selection principle for pole slot matching is explained. According to the principle of magnetic field modulation, the number of stator slots... Number of permanent magnet pole pairs in rotor Number of pole pairs of stator armature winding The relationships between them are shown below. Typically... The different pole slot matching schemes are shown in Table 4 below, where This is the winding factor.

[0084]

[0085] Table 4 Different pole slot matching schemes

[0086]

[0087] Table 4 selects the number of pole pairs for windings with a winding factor greater than 0.9, including 1, 2, 4, 10, and 11 pole pairs. When When the armature pole pairs are 1 and 2, the windings span 11 and 5 slots respectively, resulting in excessively large winding end volumes, which is unfavorable for actual prototype manufacturing. Therefore, armature pole pair numbers of 1 and 2 are not considered for the time being. The following addresses... We will conduct magnetic field harmonic analysis on schemes 4, 10, and 11.

[0088] All three schemes have 24 pairs of stationary harmonic magnetic fields in their permanent magnet fields. The following analysis focuses on the air gap harmonics of the armature magnetic field. The number of repeating units of the phase winding magnetomotive force in one mechanical cycle, for the three schemes. The values ​​are shown in Table 5 below.

[0089] Table 5. Different pole slot combinations value

[0090]

[0091] Substituting the parameters of the three schemes into the above formula, we find that only The proposed scheme meets the requirements. Theoretically, only this scheme contains 24 pairs of stationary harmonic magnetic fields in its armature magnetic field. This scheme has a high effective operating harmonic content and superior electromagnetic performance. Finite element simulations are then performed on the three schemes, ensuring that they have the same external dimensions, air gap radius, and air gap length. The torque simulation results are as follows. Figure 2 As shown.

[0092] Depend on Figure 2 Know, The scheme yields the maximum load torque, consistent with the theoretical analysis above. Therefore, when selecting the pole-slot configuration for the bidirectional modulated permanent magnet vernier motor, at least one of the six equations in Table 1 should be satisfied to ensure that the static 24 pairs of harmonic magnetic fields are utilized to generate torque. This fully demonstrates the significant guiding significance of this invention for improving the torque of bidirectional modulated permanent magnet vernier motors.

[0093] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for optimizing the pole-slot matching of a bidirectional modulated permanent magnet vernier motor, characterized in that, Includes the following steps: S1. Establish a magnetic field analysis model for the motor; S2. Analyze the harmonic components of the permanent magnet magnetic field and the armature magnetic field, and obtain the number of pole pairs and rotational speed characteristics of each harmonic. S3. Identify the stationary harmonic magnetic field generated by the stator permanent magnet. At least one stationary harmonic magnetic field exists in the armature magnetic field; the number of pole pairs is equal to the number of pole pairs of the stator permanent magnet. ; S4. Establish constraints: When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations: When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations: In the formula, This represents the harmonic order of the armature magnetomotive force. For intermediate parameters, ; The harmonic order of the air gap ratio permeability considering only the effect of stator tooth spacing variation. ; This represents the number of pole pairs of the rotor permanent magnet. The number of repeating units of the phase winding magnetomotive force in one mechanical cycle; S5. Combining the winding factor constraint, select candidate pole-slot matching schemes that meet the above conditions.

2. The pole-slot matching optimization method for a bidirectional modulated permanent magnet vernier motor according to claim 1, characterized in that, In step S1, the magnetic field analysis model of the motor includes the air gap ratio magnetic permeability model, the permanent magnet magnetomotive force model, the armature magnetomotive force model, the permanent magnet magnetic field air gap magnetic flux density model, and the armature magnetic field air gap magnetic flux density model.

3. The method for optimizing the pole-slot matching of a bidirectional modulated permanent magnet vernier motor according to claim 1, characterized in that, The winding factor constraint in step S5 is: the fundamental winding factor of the motor is not less than 0.

9.

4. The method for optimizing the pole-slot fit of a bidirectional modulated permanent magnet vernier motor according to claim 1, characterized in that, The method is applicable to bidirectional modulation single-rotor permanent magnet vernier motors, bidirectional modulation dual-rotor permanent magnet vernier motors, and bidirectional modulation dual-stator permanent magnet vernier motors.

5. A pole-slot matching optimization system for a bidirectional modulated permanent magnet vernier motor, characterized in that, include: The magnetic field modeling module is used to establish the magnetic field analysis model of the motor. The harmonic analysis module is used to analyze the harmonic components of the permanent magnet magnetic field and the armature magnetic field; The condition matching module sets a set of pole slot mating conditions, the condition set including: When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations: When the condition is met At this time, the selection principle for pole slot matching is to satisfy one of the following three equations: In the formula, This represents the harmonic order of the armature magnetomotive force. For intermediate parameters, ; The harmonic order of the air gap ratio permeability considering only the effect of stator tooth spacing variation. ; This represents the number of pole pairs of the rotor permanent magnet. The number of repeating units of the phase winding magnetomotive force in one mechanical cycle; The scheme selection module is used to select candidate schemes that meet the conditions based on the winding factor constraints. The result output module is used to output the optimized pole slot matching scheme.

6. The pole-slot matching optimization system for a bidirectional modulated permanent magnet vernier motor according to claim 5, characterized in that, The system also includes a database module for storing harmonic characteristic data of typical pole-slot mating schemes.

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