Bilateral permanent magnet Vernier motor and performance evaluation method thereof

Abstract

The application provides a double-sided permanent magnet vernier motor and a performance evaluation method thereof, and belongs to the technical field of permanent magnet variable reluctance motors. The double-sided permanent magnet vernier motor comprises a stator and a rotor coaxially arranged. The stator is provided with a plurality of stator salient poles on the side facing the air gap. The stator salient poles comprise main teeth and a plurality of auxiliary teeth. The main teeth define real slots therebetween, and the auxiliary teeth define virtual slots therebetween. Radially magnetized slot permanent magnets are arranged in the openings of the real slots and at least one virtual slot on the main teeth. Tangentially magnetized yoke permanent magnets are arranged in the other virtual slots. Armature windings are embedded in the real slots and connected. The rotor is provided with a plurality of rotor salient poles on the side facing the air gap. Rotor alternating pole permanent magnets are arranged between the rotor salient poles. The slot permanent magnets, the yoke permanent magnets and the rotor alternating pole permanent magnets form a superimposed magnetic field in the air gap, and interact with the armature magnetic field generated by the armature windings to realize bidirectional magnetic field modulation through the stator salient poles and the rotor salient poles. The double-sided permanent magnet vernier motor can solve the technical problem of low no-load back electromotive force and load torque of a conventional permanent magnet vernier motor.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet variable reluctance motor technology, and in particular to a double-sided permanent magnet vernier motor and its performance evaluation method. Background Technology

[0002] A permanent magnet vernier motor is a special type of motor that combines the characteristics of permanent magnet motors and reluctance motors. It achieves low-speed, high-torque output through the magnetic gear effect, eliminating the need for an additional mechanical reduction gear. This motor typically consists of a stator, a rotor, and permanent magnets distributed across them. Torque is generated by the interaction between the armature magnetic field and the permanent magnet excitation field. Due to its high torque density, high efficiency, and compact structure, the permanent magnet vernier motor has broad application potential in wind power generation, electric vehicles, and industrial drives.

[0003] In related technologies, permanent magnet vernier motors typically employ a dual-side permanent magnet structure for both the stator and rotor to achieve higher power factor and better torque density. In this structure, permanent magnets are mounted not only on the rotor but also on the stator side, thereby enhancing the modulation effect of the air gap magnetic field and the motor's torque output capability.

[0004] In traditional stator and rotor double-sided permanent magnet structures, stator permanent magnets are usually embedded in the yoke region of stator salient poles. However, due to the magnetic focusing effect of this spoke-type yoke permanent magnet and the bipolar flux linkage, although the motor can have a high torque density, the low-order magnetic field harmonics are reduced due to the magnetic isolation effect of the spoke-type yoke permanent magnet, and thus the torque is also reduced, resulting in relatively low no-load back electromotive force and load torque of traditional permanent magnet vernier motors. Summary of the Invention

[0005] This invention provides a double-sided permanent magnet vernier motor and its performance evaluation method, which can solve the technical problems of low no-load back electromotive force and low load torque caused by structural defects in traditional permanent magnet vernier motors. The technical solution is as follows:

[0006] In a first aspect, embodiments of the present invention provide a double-sided permanent magnet vernier motor, comprising a stator and a rotor coaxially arranged, with an air gap between the stator and the rotor, and a plurality of stator salient poles provided on the side facing the air gap, including main teeth and a plurality of auxiliary teeth disposed on the main teeth, solid slots defining the spaces between the main teeth, and dummy slots defining the spaces between the auxiliary teeth, radially magnetized slot permanent magnets being arranged in the opening of the solid slots and at least one of the dummy slots on the main teeth, and tangentially magnetized yoke permanent magnets being arranged in the other dummy slots on the main teeth, and an armature winding being embedded in the solid slot;

[0007] The rotor is provided with a plurality of rotor salient poles on the side facing the air gap, and a rotor alternating pole permanent magnet is provided between the plurality of rotor salient poles;

[0008] The stator salient pole and the rotor salient pole are used for bidirectional magnetic field modulation. The slot permanent magnet, the yoke permanent magnet and the rotor alternating pole permanent magnet are modulated in the air gap and superimposed with the permanent magnet excitation magnetic field. They interact with the modulated armature magnetic field generated by the armature winding, thereby generating effective torque.

[0009] Optionally, the number of pole pairs of the yoke permanent magnet and the slot permanent magnet are the same, and equal to the number of the actual slots.

[0010] Optionally, the stator is provided with 6 main teeth at equal angular intervals, and each main tooth is provided with 4 auxiliary teeth evenly distributed along the circumferential direction.

[0011] Optionally, the number of pole pairs of the armature winding It conforms to the following expression:

[0012]

[0013] In the formula, N SPM N represents the number of pole pairs of the yoke permanent magnet and the slot permanent magnet. RPM The number of pole pairs of the rotor's alternating pole permanent magnet is equal to the number of rotor salient poles.

[0014] Optionally, the number of pole pairs of the armature winding It conforms to the following expression:

[0015]

[0016] In the formula, N S The number of teeth in the auxiliary teeth.

[0017] Optionally, the number of pole pairs The armature windings with values ​​of 1 and 5 have the same slot pitch angle.

[0018] Secondly, embodiments of the present invention provide a performance evaluation method for evaluating the electromagnetic performance of the double-sided permanent magnet vernier motor described in the first aspect, comprising:

[0019] Step 1: Perform nonlinear finite element calculations on the simultaneous excitation of the slot permanent magnet, the yoke permanent magnet, and the rotor alternating pole permanent magnet under no-load conditions, and freeze the permeability distribution of the stator and the rotor.

[0020] Step 2: Under the condition of frozen permeability, perform linear finite element calculations on the excitation of the slot permanent magnet, the yoke permanent magnet and the rotor alternating pole permanent magnet respectively, and obtain the no-load back electromotive force and no-load air gap flux distribution and harmonic distribution of the slot permanent magnet, the yoke permanent magnet and the rotor alternating pole permanent magnet under individual excitation.

[0021] Step 3: Based on the no-load air gap harmonic distribution in Step 2, calculate the no-load back EMF contribution of the main working harmonics by using a unified no-load back EMF equation, and then derive the no-load back EMF under individual excitation of the slot permanent magnet, the yoke permanent magnet, and the rotor alternating pole permanent magnet.

[0022] Step 4: Compare the no-load back EMF obtained by pure finite element method in Step 2 with the no-load back EMF obtained by hybrid finite element method-numerical calculation in Step 3.

[0023] Optionally, it also includes:

[0024] Step 5: Perform nonlinear finite element calculations on the simultaneous excitation of the slot permanent magnet, the yoke permanent magnet, and the rotor alternating pole permanent magnet under load conditions, and freeze the permeability distribution of the stator and the rotor.

[0025] Step 6: Under the condition of frozen permeability, perform linear finite element calculations on the excitation of the slot permanent magnet, the yoke permanent magnet and the rotor alternating pole permanent magnet respectively, and obtain the load torque of the slot permanent magnet, the yoke permanent magnet and the rotor alternating pole permanent magnet under individual excitation.

[0026] Step 7: Based on the no-load air gap harmonic distribution in Step 2, calculate the average torque contribution of the main working harmonics through the unified load torque equation, and then derive the load torque under individual excitation of the slot permanent magnet, the yoke permanent magnet, and the rotor alternating pole permanent magnet.

[0027] Step 8: Compare the load torque obtained by pure finite element method in Step 6 with the load torque obtained by hybrid finite element method numerical calculation in Step 7.

[0028] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0029] The double-sided permanent magnet vernier motor provided in this invention, compared with the traditional double-sided permanent magnet vernier motor stator and rotor structure, optimizes the stator salient pole structure. A set of slot-oriented magnetized slot permanent magnets is added to the solid slot openings between the main teeth and the virtual slots between the auxiliary teeth. This set of slot permanent magnets, together with the yoke permanent magnets between other auxiliary teeth and the rotor alternating pole permanent magnets located between the rotor salient poles on the other side of the air gap, form a parallel magnetic field. This creates a superimposed magnetic field in the air gap. The magnetic fields of the three sets of permanent magnets—slot permanent magnets, yoke permanent magnets, and rotor alternating pole permanent magnets—and the armature magnetic field generated by the armature winding are simultaneously modulated by the stator salient poles and rotor salient poles in a bidirectional magnetic field, generating more magnetic field harmonics that contribute to torque generation. This effectively solves the technical problems of low no-load back electromotive force and low load torque caused by structural defects in traditional permanent magnet vernier motors. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a three-dimensional structural disassembly diagram of a double-sided permanent magnet vernier motor provided in an embodiment of the present invention;

[0032] Figure 2 This is a front view of another double-sided permanent magnet vernier motor provided in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the armature winding connection method provided in an embodiment of the present invention;

[0034] Figure 4 This is an empty magnetic flux path diagram of the highest positive magnetic flux point of the yoke permanent magnet provided in an embodiment of the present invention;

[0035] Figure 5 This is an empty magnetic flux path diagram of the highest point of reverse magnetic flux of the yoke permanent magnet provided in an embodiment of the present invention;

[0036] Figure 6 This is a diagram of the unloaded magnetic flux path at the highest positive point of the slotted permanent magnet provided in an embodiment of the present invention.

[0037] Figure 7 This is an empty magnetic flux path diagram of the highest point of reverse magnetic flux of the slot permanent magnet provided in the embodiment of the present invention;

[0038] Figure 8 This is an empty magnetic flux path diagram of the highest positive magnetic flux point of the rotor alternating pole permanent magnet provided in an embodiment of the present invention;

[0039] Figure 9 This is an empty magnetic flux path diagram of the highest point of reverse magnetic flux of the rotor alternating pole permanent magnet provided in the embodiment of the present invention;

[0040] Figure 10 This is a schematic diagram of the unloaded phase flux linkage under different excitation conditions provided in the embodiments of the present invention;

[0041] Figure 11 This is a partial structural enlarged view of the double-sided permanent magnet vernier motor provided in an embodiment of the present invention;

[0042] Figure 12 This is a flowchart of steps 1 to 4 of the performance evaluation method provided in this embodiment of the invention;

[0043] Figure 13 This is a flowchart of steps 5 to 8 of the performance evaluation method provided in the embodiments of the present invention.

[0044] In the picture:

[0045] 1-Stator; 2-Rotor; 11-Stator salient pole; 12-Slot permanent magnet; 13-Yoke permanent magnet; 14-Armature winding; 21-Rotor salient pole; 22-Rotor alternating pole permanent magnet; 111-Main tooth; 112-Auxiliary tooth; 111a-Solid slot; 112a-Virtual slot. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0047] Figure 1 This is a three-dimensional structural disassembly diagram of a double-sided permanent magnet vernier motor provided in an embodiment of the present invention; Figure 2 This is a front view of another double-sided permanent magnet vernier motor provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the armature winding connection method provided in an embodiment of the present invention; Figure 4 This is an empty magnetic flux path diagram of the highest positive magnetic flux point of the yoke permanent magnet provided in an embodiment of the present invention; Figure 5 This is an empty magnetic flux path diagram of the highest point of reverse magnetic flux of the yoke permanent magnet provided in an embodiment of the present invention; Figure 6 This is a diagram of the unloaded magnetic flux path at the highest positive point of the slotted permanent magnet provided in an embodiment of the present invention. Figure 7 This is an empty magnetic flux path diagram of the highest point of reverse magnetic flux of the slot permanent magnet provided in the embodiment of the present invention; Figure 8 This is an empty magnetic flux path diagram of the highest positive magnetic flux point of the rotor alternating pole permanent magnet provided in an embodiment of the present invention; Figure 9 This is an empty magnetic flux path diagram of the highest point of reverse magnetic flux of the rotor alternating pole permanent magnet provided in the embodiment of the present invention; Figure 10 This is a schematic diagram of the unloaded phase flux linkage under different excitation conditions provided in the embodiments of the present invention; Figure 11 This is an enlarged view of a partial structure of the double-sided permanent magnet vernier motor provided in an embodiment of the present invention. For example... Figures 1 to 11 As shown, an embodiment of the present invention provides a double-sided permanent magnet vernier motor, including a stator 1 and a rotor 2 arranged coaxially, with an air gap between the stator 1 and the rotor 2.

[0048] The stator 1 has several stator salient poles 11 facing the air gap, including main teeth 111 and several auxiliary teeth 112 disposed on the main teeth 111. Solid slots 111a are defined between the main teeth 111, and virtual slots 112a are defined between the auxiliary teeth 112. Radially magnetized slot permanent magnets 12 are arranged in the opening of the solid slot 111a and in at least one virtual slot 112a on the main teeth 111. Tangentially magnetized yoke permanent magnets 13 are arranged in the other virtual slots 112a on the main teeth 111. An armature winding 14 is embedded in the solid slot 111a.

[0049] The rotor 2 has several rotor salient poles 21 facing the air gap side, and rotor alternating pole permanent magnets 22 are arranged between the several rotor salient poles 21.

[0050] The stator salient pole 11 and the rotor salient pole 21 are used for bidirectional magnetic field modulation. The slot permanent magnet 12, the yoke permanent magnet 13 and the rotor alternating pole permanent magnet 22 are modulated in the air gap and superimposed with the permanent magnet excitation magnetic field. They interact with the modulated armature magnetic field generated by the armature winding 14, thereby generating effective torque.

[0051] In this embodiment of the invention, a ring-shaped rotor core is used as the outer rotor of the rotor 2. The stator 1 is coaxially disposed inside the rotor 2. The stator 1 consists of a cylindrical iron core body located at the center and six stator salient poles 11 arranged at equal angles on its outer sidewalls. Each stator salient pole 11 includes a main tooth 111 that protrudes radially along the sidewall of the iron core body. The end segment of each main tooth 111 extends to both sides along the circumference of the iron core body and protrudes radially outward again to form four auxiliary teeth 112. In the circumference of the stator 1, a solid slot 111a is defined between adjacent main teeth 111, and a virtual slot 112a is defined between auxiliary teeth 112. The armature winding 14 adopts a distributed winding arrangement spanning two main teeth 111. Each phase armature winding 14 is embedded and arranged inside the solid slot 111a across two main teeth 111 and connected in series. Three sets of permanent magnets are provided in conjunction with the stator 1: slot permanent magnets 12 magnetized radially along the stator 1, yoke permanent magnets 13 magnetized tangentially along the stator 1, and rotor alternating pole permanent magnets 22 magnetized radially along the rotor 2. Each main tooth 111 has four auxiliary teeth 112 defining three virtual slots 112a on the side of the main tooth 111 near the air gap. A slot permanent magnet 12 is provided at the opening of the middle virtual slot 112a and each solid slot 111a on each main tooth 111. A yoke permanent magnet 13 is provided in the two virtual slots 112a on either side of the middle virtual slot 112a on each main tooth 111. The rotor 2 has several rotor salient poles 21 evenly spaced on the side facing the air gap, and rotor alternating pole permanent magnets 22 are provided in the slot structure between adjacent rotor salient poles 21. Furthermore, the tangential magnetization direction of the yoke permanent magnet 13 in each main tooth 111 is towards the adjacent solid slot 111a, the slot permanent magnet 12 located in the middle virtual slot 112a is directed towards the air gap magnetization, and the slot permanent magnet 12 at the slot opening of the solid slot 111a is magnetized away from the air gap.

[0052] Compared with the traditional stator and rotor structure of the double-sided permanent magnet vernier motor provided by the embodiments of the present invention, the stator salient pole structure is optimized. A set of directional magnetized slot permanent magnets 12 are added to the opening of the solid slot 111a between the main teeth 111 and the virtual slot 112a between the auxiliary teeth 112. The slot permanent magnets 12, together with the yoke permanent magnets 13 between the other auxiliary teeth 112 and the rotor alternating pole permanent magnets 22 located between the rotor salient poles 21 on the other side of the air gap, form a parallel magnetic field, thereby constructing a superimposed magnetic field in the air gap. The magnetic fields of the three sets of permanent magnets, namely the slot permanent magnets 12, the yoke permanent magnets 13 and the rotor alternating pole permanent magnets 22, and the armature magnetic field generated by the armature winding 14, are simultaneously subjected to bidirectional magnetic field modulation by the stator salient poles 11 and the rotor salient poles 21, generating more magnetic field harmonics that help generate torque, thereby effectively solving the technical problems of low no-load back electromotive force and low load torque caused by structural defects in traditional permanent magnet vernier motors.

[0053] Specifically, in this embodiment of the invention, the number of pole pairs of the yoke permanent magnet 13 and the slot permanent magnet 12 are the same, and equal to the number of solid slots 111a. SPM N represents the number of pole pairs of the yoke permanent magnet 13 and the slot permanent magnet 12, and the number of teeth N of the auxiliary teeth 112 on the stator 1. s The number of stator slots, that is, the sum of the number of real slots 111a and virtual slots 112a, is equal to the number of pole pairs of the yoke permanent magnets 13 and the slot permanent magnets 12. In other words:

[0054] (1)

[0055] Furthermore, the number of pole pairs of the armature winding 14 is determined based on the yoke permanent magnet 13 and the slot permanent magnet 12. It can be represented as:

[0056] (2)

[0057] In the formula, N SPM N represents the number of pole pairs of the yoke permanent magnet 13 and the slot permanent magnet 12. RPM The number of pole pairs of the rotor alternating pole permanent magnet 22 is equal to the number of rotor salient poles 21.

[0058] Furthermore, the number of pole pairs of the armature winding 14 is obtained based on the rotor salient pole 21. It conforms to the following expression:

[0059] (3)

[0060] In the formula, N S The number of teeth for auxiliary tooth 112.

[0061] According to equation (2), the double-sided permanent magnet vernier motor provided in this embodiment of the invention mainly utilizes the third harmonic of the stator permanent magnet magnetomotive force for operation. According to equation (3), the double-sided permanent magnet vernier motor provided in this embodiment of the invention mainly utilizes the fundamental wave of the rotor permanent magnet magnetomotive force.

[0062] In this embodiment of the invention, due to the number of auxiliary teeth N of the motor s It is 24, the extreme logarithm. Armature windings 14 with values ​​of 1 and 5 have the same slot pitch angle and the same winding connection method. Armature windings 14 with values ​​of 1 and 5 can fully utilize the magnetic field harmonics of the yoke permanent magnet 13, slot permanent magnet 12, and rotor alternating pole permanent magnet 22, especially the air gap magnetic flux density harmonics of one-pole and five-pole pairs. According to equations (2) and (3), the double-sided permanent magnet vernier motor of this scheme mainly utilizes the third harmonic of the stator permanent magnet magnetomotive force and the fundamental magnetomotive force of the rotor permanent magnet. Figure 3The connection method of the armature winding 14 in the double-sided permanent magnet vernier motor is shown. Through the combined effect of the third harmonic of the stator permanent magnet magnetomotive force and the fundamental wave of the rotor permanent magnet magnetomotive force, the pair-pole air gap magnetic flux density harmonic of the motor proposed in this embodiment of the invention is significantly enhanced, resulting in better no-load back electromotive force and load torque than traditional double-sided permanent magnet vernier motors.

[0063] For example, Figures 4 to 9 The unloaded magnetic flux paths of three sets of permanent magnets in typical rotor positions are shown, revealing the principle of magnetic flux superposition. For example... Figure 10 As shown, when the stator teeth and rotor salient poles are at the maximum positive magnetic flux (position A) and the maximum negative magnetic flux (position B), a magnetic flux switching effect will occur, resulting in a sinusoidal distribution of magnetic flux in each phase.

[0064] Figure 12 This is a flowchart of steps 1 to 4 of the performance evaluation method provided in this embodiment of the invention; Figure 13 This is a flowchart of steps 5 to 8 of the performance evaluation method provided in this embodiment of the invention. Figures 12 to 13 As shown, embodiments of the present invention also provide a performance evaluation method for evaluating, for example, Figures 1 to 2 The electromagnetic properties of the bilateral permanent magnet vernier motor shown include:

[0065] Step 1: Perform nonlinear finite element calculations on the simultaneous excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22 under no-load conditions, and freeze the permeability distribution of the rotor stator 1 and rotor 2.

[0066] Step 2: Under the condition of frozen permeability, linear finite element calculations are performed on the excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22, respectively, to obtain the no-load back electromotive force and no-load air gap flux distribution and harmonic distribution under individual excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22.

[0067] Step 3: Based on the no-load air gap harmonic distribution in Step 2, the no-load back EMF contribution of the main working harmonics is calculated by unifying the no-load back EMF equation, and then the no-load back EMF under individual excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22 is derived.

[0068] Step 4: Compare the no-load back EMF obtained by pure finite element method in Step 2 with the no-load back EMF obtained by hybrid finite element method-numerical calculation in Step 3.

[0069] Step 5: Perform nonlinear finite element calculations on the simultaneous excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22 under load conditions, and freeze the permeability distribution of the rotor stator 1 and rotor 2.

[0070] Step 6: Under the condition of frozen permeability, perform linear finite element calculations to excite the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22 respectively, and obtain the load torque under individual excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22 respectively.

[0071] Step 7: Based on the no-load air gap harmonic distribution in Step 2, the average torque contribution of the main working harmonics is calculated by using the unified load torque equation, and then the load torque under individual excitation of the rotor slot permanent magnet 12, the rotor yoke permanent magnet 13, and the rotor alternating pole permanent magnet 22 is derived.

[0072] Step 8: Compare the load torque obtained by pure finite element method in step 6 with the load torque obtained by hybrid finite element method-numerical calculation in step 7.

[0073] For example, in the embodiments of the present invention, the above-mentioned performance evaluation method can be used to quantitatively evaluate the performance improvement of the no-load back EMF and load torque of the dual-sided permanent magnet vernier motor proposed in this solution compared with the traditional dual-sided permanent magnet vernier motor, so that the no-load back EMF / load torque under different configurations are comparable and verifiable, providing data support for subsequent iterative optimization.

[0074] Specifically, to study the air gap magnetic flux density and its harmonic distribution characteristics, an air gap magnetomotive force-permeability model was established, and the magnetic field components and torque contributions of each working harmonic were analyzed in detail. The following simplifying assumptions were used in the model derivation:

[0075] (1) Ignore the edge effect of the stator permanent magnet;

[0076] (2) The core saturation effect is not considered;

[0077] (3) Set the rotor salient pole axis and the A-phase winding axis to be initially aligned with the coordinate origin.

[0078] The air gap magnetomotive force-permeability model is as follows: Figure 11 As shown, This indicates the tooth arc angle of auxiliary tooth 112. The width of the stator slot. The tooth arc angle represents the rotor salient pole 21.

[0079] The unloaded air gap magnetic flux density can be expressed as:

[0080] (4)

[0081] in, denoted as the mechanical angle along the circumference of the air gap; g is the length of the air gap. air permeability; The magnetomotive force is for excitation by three sets of permanent magnets; Stator magnetic permeability when there is a slotted stator (with stator salient poles) and a smooth rotor; Rotor magnetic permeability when there is a slotted rotor (with rotor salient poles) and a smooth stator.

[0082] The equivalent magnetomotive force generated by the stator permanent magnets (slot permanent magnet 12 and yoke permanent magnet 13) can be expressed as:

[0083] (5)

[0084] (6)

[0085] in, and It is the equivalent yoke permanent magnet magnetomotive force and the equivalent slot permanent magnet magnetomotive force modulated by auxiliary tooth 112; and These are the equivalent yoke permanent magnet magnetomotive force and the equivalent slot permanent magnet magnetomotive force amplitudes, respectively, for the nth harmonic.

[0086] The rotor permeability with a smooth stator and a slotted rotor can be expressed as:

[0087] (7)

[0088] in, It is the mechanical angular velocity; This represents the number of salient poles of the rotor. The rotor has constant magnetic permeability; for The rotor permeability amplitude of the subharmonic.

[0089] The equivalent magnetomotive force generated by the rotor permanent magnet (rotor alternating pole permanent magnet 22) can be expressed as:

[0090] (8)

[0091] in, It is the equivalent rotor permanent magnet magnetomotive force modulated by rotor salient pole 21. The equivalent rotor permanent magnet magnetomotive force amplitude is the mth harmonic.

[0092] The stator magnetic permeability with a slotted stator and a smooth rotor can be expressed as:

[0093] (9)

[0094] in, Stator constant magnetic permeability; Let be the stator magnetic permeability amplitude of the kth harmonic.

[0095] Substituting equations (5) and (7) into equation (4), the air gap magnetic flux density of the unloaded yoke permanent magnet 13 can be expressed as:

[0096]

[0097] (10)

[0098] Substituting equations (6) and (7) into equation (4), the air gap magnetic flux density of the unloaded slot permanent magnet 12 can be expressed as:

[0099]

[0100] (11)

[0101] Substituting equations (8) and (9) into equation (4), the air gap magnetic flux density of the unloaded rotor alternating pole permanent magnet 22 can be expressed as:

[0102]

[0103] (12)

[0104] Furthermore, the unloaded air gap magnetic flux density can be expressed as:

[0105] (13)

[0106] Furthermore, the no-load back electromotive force of armature winding 14 can be expressed as:

[0107] (14)

[0108] In the formula, The radius of the air gap circumference; The length of the iron core; The armature winding function can be further expressed as:

[0109] (15)

[0110] In the formula, This represents the number of series turns per phase of armature winding 14; Let the winding coefficient of the i-th pair of harmonics be expressed as:

[0111] (16)

[0112] in, This refers to the pitch coefficient; q is the distribution coefficient; q is the number of coils per pole per phase; The slot pitch angle; The coil pitch; Let be the polar moment. Then q and It can be represented as:

[0113] (17)

[0114] In the formula, This represents the number of pole pairs in armature winding 14; This refers to the number of stator slots; The phase number.

[0115] Substituting equations (13) and (15) into equation (14), the magnitude of the back electromotive force of the unloaded armature winding 14 can be expressed as:

[0116]

[0117]

[0118]

[0119] (18)

[0120] (19)

[0121] In the formula, , and These are the open-circuit back electromotive forces generated by the yoke permanent magnet 13, the slot permanent magnet 12, and the rotor alternating pole permanent magnet 22, respectively. , and These are the harmonic amplitudes of the i-pole air gap magnetic flux density excited by the yoke permanent magnet 13, slot permanent magnet 12, and rotor alternating pole permanent magnet 22, respectively. Let the electric angular velocity of the i-th pair of harmonics be calculated as follows:

[0122] (20)

[0123] In the formula, m=1. Therefore, the amplitude of the open-circuit back electromotive force can be derived as follows:

[0124]

[0125]

[0126]

[0127]

[0128] (twenty one)

[0129] In the formula, The open-circuit back electromotive force (EMF) amplitude generated by the i-pole air gap magnetic flux density harmonics jointly excited by the yoke permanent magnet 13, slot permanent magnet 12, and rotor alternating pole permanent magnet 22 is given. The proportion of the open-circuit back EMF of the i-pole air gap magnetic flux density harmonics can be defined as:

[0130] (twenty two)

[0131] According to the Lorentz force law, the electromagnetic torque of the load can be expressed as:

[0132] (twenty three)

[0133] In the formula, For a current load, it can be represented as:

[0134] (twenty four)

[0135] and Let be the air gap magnetic flux density of the load. Since the salient pole effect of the motor in this scheme is extremely low, the reluctance torque can be neglected. Therefore, the load electromagnetic torque can be further expressed as:

[0136] (25)

[0137] It is generally accepted that a motor can only generate effective torque when the no-load air gap flux density harmonics and the current load component have the same number of pole pairs. Considering the dominant operating harmonics, the average torque can be expressed as:

[0138]

[0139]

[0140]

[0141]

[0142] (26)

[0143] In the formula, , and The load torques generated by the yoke permanent magnet 13, slot permanent magnet 12, and rotor alternating pole permanent magnet 22 are respectively. , and The permanent magnets 13 in the yoke, 12 in the slot, and 22 in the rotor are respectively excited by the permanent magnets 13 in the slot and 12 in the rotor. The load torque generated by the harmonics of the air gap magnetic flux density. The torque proportion of the polar air gap magnetic flux density harmonics is defined as follows:

[0144] (27)

[0145] Using the above performance evaluation method, compared with the traditional double-sided permanent magnet vernier motor, this new double-sided permanent magnet vernier motor adds a set of slot permanent magnets 12 in the opening of the solid slot 111a and the virtual slot 112a on the stator 1. Tables 1 and 2 below show the contribution of each harmonic to the no-load back EMF and load torque of the traditional and new double-sided permanent magnet vernier motors, where the rotor permanent magnet is the rotor alternating pole permanent magnet 22. Analysis shows that the 1-pole and 19-pole magnetic flux density harmonics are the main sources of torque generation in both motor structures. From the perspective of harmonic composition: in the traditional structure, the 1, 13, 25, and 37-pole harmonics generated by the stator permanent magnet and the 1, 5, 19, and 43-pole harmonics generated by the rotor permanent magnet jointly participate in torque generation. The structure provided in this embodiment of the invention maintains the same harmonic composition mode, but the contribution of each harmonic has changed significantly.

[0146] Among them, the harmonics of the air gap magnetic flux density of the first pair of poles play a dominant role in electromagnetic performance, with a contribution rate of 53.401% in the traditional double-sided permanent magnet vernier motor and an increase to 56.245% in the new structure. Comparative analysis shows that the amplitudes of the harmonics of the 1st, 13th, 25th, and 37th pairs of poles of the new double-sided permanent magnet vernier motor are significantly improved, while the amplitudes of the harmonics of the 5th, 19th, and 43rd pairs of poles are relatively reduced, effectively improving the no-load back EMF and load torque performance.

[0147] Table 1

[0148] No-load back EMF and load torque harmonic contribution of traditional double-sided permanent magnet vernier motor

[0149]

[0150] Table 2

[0151] The no-load back electromotive force and load torque harmonic contributions proposed in the embodiments of the present invention

[0152]

[0153] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses all elements or objects listed following “comprising” or “including” and are identical to them, but do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. “Up,” “down,” “left,” “right,” etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0154] The above description is merely an optional embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A double-sided permanent magnet vernier motor, comprising a stator (1) and a rotor (2) coaxially arranged, wherein an air gap exists between the stator (1) and the rotor (2), characterized in that, The stator (1) is provided with a plurality of stator salient poles (11) facing the air gap side, including main teeth (111) and a plurality of auxiliary teeth (112) disposed on the main teeth (111). Solid slots (111a) are defined between the main teeth (111), and virtual slots (112a) are defined between the auxiliary teeth (112). Radially magnetized slot permanent magnets (12) are arranged in the opening of the solid slots (111a) and at least one of the virtual slots (112a) on the main teeth (111). 1) Tangentially magnetized yoke permanent magnets (13) are arranged in the other virtual slots (112a) on the upper part, and an armature winding (14) is embedded in the solid slot (111a). The tangential magnetization direction of the yoke permanent magnet (13) in each main tooth (111) is towards the adjacent solid slot (111a). The slot permanent magnet (12) located in the virtual slot (112a) is magnetized towards the air gap, and the slot permanent magnet (12) at the slot opening of the solid slot (111a) is magnetized away from the air gap. The rotor (2) is provided with a plurality of rotor salient poles (21) facing the air gap side, and a rotor alternating pole permanent magnet (22) magnetized radially along the rotor (21) is provided between the plurality of rotor salient poles (21). The stator salient pole (11) and the rotor salient pole (21) are used for bidirectional magnetic field modulation. The slot permanent magnet (12), the yoke permanent magnet (13) and the rotor alternating pole permanent magnet (22) are modulated in the air gap and superimposed with the permanent magnet excitation magnetic field. They interact with the modulated armature magnetic field generated by the armature winding (14) to generate effective torque.

2. The double-sided permanent magnet vernier motor according to claim 1, characterized in that, The number of pole pairs of the yoke permanent magnet (13) and the slot permanent magnet (12) are the same, and the number of the slots is equal to that of the solid slots (111a).

3. The double-sided permanent magnet vernier motor according to claim 2, characterized in that, The stator (1) has 6 main teeth (111) spaced at equal angles, and each main tooth (111) has 4 auxiliary teeth (112) evenly spaced along the circumference.

4. The double-sided permanent magnet vernier motor according to claim 2, characterized in that, The number of pole pairs of the armature winding (14) PPN a It conforms to the following expression: In the formula, N SPM N is the number of pole pairs of the yoke permanent magnet (13) and the slot permanent magnet (12). RPM The number of pole pairs of the rotor alternating pole permanent magnet (22) is equal to the number of rotor salient poles (21).

5. The double-sided permanent magnet vernier motor according to claim 4, characterized in that, The number of pole pairs of the armature winding (14) PPN a It conforms to the following expression: In the formula, N S The number of teeth of the auxiliary tooth (112).

6. The double-sided permanent magnet vernier motor according to claim 5, characterized in that, The pole pair number PPN a The armature windings (14) with values ​​of 1 and 5 have the same slot pitch angle.

7. A performance evaluation method for assessing the electromagnetic performance of the double-sided permanent magnet vernier motor according to any one of claims 1 to 6, characterized in that, include: Step 1: Perform nonlinear finite element calculations on the simultaneous excitation of the slot permanent magnet (12), the yoke permanent magnet (13), and the rotor alternating pole permanent magnet (22) under no-load conditions, and freeze the permeability distribution of the stator (1) and the rotor (2); Step 2: Under the condition of frozen permeability, linear finite element calculations are performed on the excitation of the slot permanent magnet (12), the yoke permanent magnet (13), and the rotor alternating pole permanent magnet (22) to obtain the no-load back electromotive force and no-load air gap flux distribution and harmonic distribution of the slot permanent magnet (12), the yoke permanent magnet (13), and the rotor alternating pole permanent magnet (22) under individual excitation. Step 3: Based on the no-load air gap harmonic distribution in Step 2, calculate the no-load back EMF contribution of the main working harmonics by using the unified no-load back EMF equation, and then derive the no-load back EMF under individual excitation of the slot permanent magnet (12), the yoke permanent magnet (13), and the rotor alternating pole permanent magnet (22). Step 4: Compare the no-load back EMF obtained by pure finite element method in Step 2 with the no-load back EMF obtained by hybrid finite element method-numerical calculation in Step 3.

8. The performance evaluation method according to claim 7, characterized in that, Also includes: Step 5: Perform nonlinear finite element calculations on the simultaneous excitation of the slot permanent magnet (12), the yoke permanent magnet (13), and the rotor alternating pole permanent magnet (22) under load conditions, and freeze the permeability distribution of the stator (1) and the rotor (2); Step 6: Under the condition of frozen permeability, perform linear finite element calculations on the excitation of the slot permanent magnet (12), the yoke permanent magnet (13) and the rotor alternating pole permanent magnet (22) respectively, and obtain the load torque of the slot permanent magnet (12), the yoke permanent magnet (13) and the rotor alternating pole permanent magnet (22) under individual excitation respectively. Step 7: Based on the no-load air gap harmonic distribution in Step 2, calculate the average torque contribution of the main working harmonics through the unified load torque equation, and then derive the load torque of the slot permanent magnet (12), the yoke permanent magnet (13) and the rotor alternating pole permanent magnet (22) under individual excitation. Step 8: Compare the load torque obtained by pure finite element method in Step 6 with the load torque obtained by hybrid finite element method numerical calculation in Step 7.

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