Four-pole synchronous motor and method for reducing cogging torque of four-pole synchronous motor

Abstract

The present invention proposes a four-pole synchronous motor and a method for reducing the cogging torque of a four-pole synchronous motor. The four-pole synchronous motor comprises: a motor stator, provided with a plurality of teeth; a motor rotor, seven first permanent magnets and one second permanent magnet forming four pairs of poles of the motor rotor; the center angle θ1 corresponding to the first permanent magnet satisfies the relationship: #imgabs0# the center angle θ2 corresponding to the second permanent magnet satisfies the relationship: #imgabs1# wherein, #imgabs2# is the permanent magnet pole arc coefficient, #imgabs3# α is the motor fundamental wave cogging torque cycle, α=360÷N; N is the number of motor fundamental wave cogging torque cycles, N=LCM(Z, 8), Z is the number of the plurality of teeth; θ0 is the center angle corresponding to each of the permanent magnets when all the permanent magnets are equally distributed, that is, #imgabs4# the present application can further reduce the cogging torque of a four-pole motor with Z teeth, avoid motor speed fluctuation, vibration and noise caused by large cogging torque, and has a simple structure, reducing the difficulty of processing.

Description

Technical Field

[0001] The present application relates to the technical field of motor cogging torque, and in particular to a four-pole synchronous motor and a method for reducing the cogging torque of the four-pole synchronous motor. Background Art

[0002] Four pole pairs are widely used in synchronous motors. Compared with synchronous motors with smaller pole pairs, four pole pairs have the advantage of greater output, and compared with synchronous motors with larger pole pairs, four pole pairs have the advantage of higher speed operation. Figure 1 As shown, the equally distributed permanent magnets 100 of the motor rotor are evenly arranged on the circumference of the motor core, as shown in FIG. Figure 4 As shown, the cogging torque is large, which in turn causes motor speed fluctuation, vibration and noise, and also increases the initial starting torque of the motor.

[0003] At present, the methods for reducing the cogging torque of a synchronous motor with four pairs of poles include stator skew slots and rotor skew poles or segmented staggered rotor poles. Stator skew slots and rotor skew poles are to offset the cut stator slots or rotor permanent magnets by a certain angle during the processing of the stator and rotor. The method of segmented staggered rotor poles is to offset the angle of each rotor section with the upper rotor section when the rotor is bonded. Among them, the method of stator skew slots and rotor skew poles will increase the difficulty of processing the stator or rotor and increase the manufacturing cost. The method of segmented staggered rotor poles is not easy to implement in terms of technology, which increases the difficulty of manufacturing.

[0004] Therefore, seeking a four-pole synchronous motor that is easy to produce and process and effectively reduces the cogging torque has become a concern for technicians. Summary of the invention

[0005] The purpose of the present application is to provide a four-pole synchronous motor to solve the problems of large cogging torque and complex production process of the four-pole synchronous motor in the prior art.

[0006] To solve the above technical problems, according to some embodiments, the present application provides a four-pole synchronous motor, including:

[0007] The motor stator is provided with a plurality of tooth slots;

[0008] A motor rotor, wherein seven first permanent magnets and one second permanent magnet constitute four pairs of poles of the motor rotor;

[0009] The central angle θ1 corresponding to the first permanent magnet satisfies the relationship: The central angle θ2 corresponding to the second permanent magnet satisfies the relationship: in, is the permanent magnet pole arc coefficient, α is the motor fundamental wave toothing torque period, α=360÷N; N is the number of motor fundamental wave toothing torque periods, N=LCM(Z,8), Z is the number of the plurality of tooth slots; θ0 is the central angle corresponding to each permanent magnet when all the permanent magnets are equally spaced, that is,

[0010] Furthermore, the N poles and S poles of adjacent permanent magnets are arranged with different polarities at intervals.

[0011] Furthermore, gaps are provided between adjacent permanent magnets or they are separated by blocking blocks.

[0012] Furthermore, the first permanent magnet and the second permanent magnet are both arc-shaped magnetic steel sheets.

[0013] Furthermore, the second permanent magnet and the seven first permanent magnets are bonded and arranged around the outer circumferential surface of the motor rotor.

[0014] Furthermore, the plurality of tooth slots is 12; the permanent magnet pole arc coefficient Yes 1.

[0015] Another aspect of the present application provides a method for reducing the cogging torque of a four-pole synchronous motor, wherein the four-pole synchronous motor comprises a motor rotor and a motor stator, wherein eight permanent magnets constitute four pairs of poles of the motor rotor; the motor stator has a plurality of tooth slots; and the steps of reducing the cogging torque of the four-pole synchronous motor include:

[0016] S1. According to the number of tooth slots Z of the motor stator of the four-pole synchronous motor, determine the number of fundamental wave tooth slot torque cycles N of the motor, N = LCM (Z, 8);

[0017] S2. According to the fundamental wave cogging torque cycle number N of the motor, determine the motor fundamental wave cogging torque cycle α, α = 360 ÷ N;

[0018] S3. Calculate the center angle θ0 corresponding to each of the eight permanent magnets when the center angles of the eight permanent magnets are equally divided. in, is the permanent magnet pole arc coefficient

[0019] S4. Determine the central angle θ1 corresponding to the seven first permanent magnets among the eight permanent magnets, satisfying the relationship:

[0020] S5. Determine the central angle θ2 corresponding to a second permanent magnet among the eight permanent magnets, satisfying the relationship:

[0021] Furthermore, the method further comprises:

[0022] The N poles and S poles of the adjacent permanent magnets are arranged with different poles and intervals.

[0023] The four-pole synchronous motor proposed in the present application comprises: a motor stator, provided with a plurality of tooth slots; a motor rotor, seven first permanent magnets and one second permanent magnet constituting four pairs of poles of the motor rotor, the center angle corresponding to the first permanent magnet is different from the center angle corresponding to the second permanent magnet; the center angle θ1 corresponding to the first permanent magnet satisfies the relationship: The central angle θ2 corresponding to the second permanent magnet satisfies the relationship: in, is the permanent magnet pole arc coefficient, α is the motor fundamental wave toothing torque period, α=360÷N; N is the number of motor fundamental wave toothing torque periods, N=LCM(Z,8), Z is the number of the plurality of tooth slots; θ0 is the central angle corresponding to each permanent magnet when all the permanent magnets are equally spaced, that is, In the present application, the center angle corresponding to the first permanent magnet of the motor rotor in the four-pole synchronous motor is different from the center angle corresponding to the second permanent magnet, which can effectively reduce the cogging torque of the four-pole synchronous motor, and the structure is simple. Furthermore, the number of tooth slots of the motor stator is different, the center angle corresponding to the first permanent magnet of the motor rotor is different, and the center angle corresponding to the second permanent magnet is also different. The center angle corresponding to the first permanent magnet and the center angle corresponding to the second permanent magnet determined according to the number of tooth slots of the motor stator can further reduce the cogging torque of the four-pole motor with Z tooth slots, avoid motor speed fluctuations, vibrations and noise caused by large cogging torque, and the structure is simple, reducing the difficulty of processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a cross-sectional schematic diagram of a motor with 8 permanent magnets arranged equally in the background technology of this application;

[0026] Figure 2 This is a schematic diagram of the distribution of permanent magnets of a motor rotor of a four-pole synchronous motor in one embodiment of the present application;

[0027] Figure 3 is a cross-sectional schematic diagram of a four-pole synchronous motor with 12 tooth slots in one embodiment of the present application;

[0028] Figure 4It is a cogging torque waveform diagram of a motor with 8 permanent magnets equally arranged in the background technology of this application;

[0029] Figure 5 This is a cogging torque waveform diagram of a four-pole synchronous motor in one embodiment of the present application.

[0030] in, Figures 1 to 5 The corresponding relationship between the reference numerals and component names in the figure is:

[0031] 1. Motor rotor; 101. First permanent magnet; 103. Second permanent magnet; 100. Equally divided permanent magnet; 2. Motor stator; 201. Tooth slot. DETAILED DESCRIPTION

[0032] At present, the four-pole motor in the prior art has the problems of large cogging torque and complex production process.

[0033] It should be noted that the cogging torque is the torque generated by the interaction between the permanent magnet and the iron core when the permanent magnet motor winding is not energized. It is caused by the tangential component of the interaction force between the permanent magnet and the armature teeth.

[0034] To solve the above problem, an embodiment of the present application provides a four-pole synchronous motor, in which the permanent magnets of the motor rotor 1 are divided into seven equally divided first permanent magnets 101 and one unequally divided second permanent magnet 103, and the center angle corresponding to the first permanent magnet 101 and the center angle corresponding to the second permanent magnet 103 are calculated and determined according to the number of motor teeth 201.

[0035] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not be construed as any limitation, and the various embodiments can be combined with each other and quoted from each other without contradiction.

[0036] like Figure 2 and Figure 3 As shown, an embodiment of the present application provides a four-pole synchronous motor, including: a motor stator 2, provided with a plurality of tooth slots 201; a motor rotor 1, seven first permanent magnets 101 and one second permanent magnet 103 forming four pairs of poles of the motor rotor 1; the central angle θ1 corresponding to the first permanent magnet 101 satisfies the relationship: The central angle θ2 corresponding to the second permanent magnet 103 satisfies the relationship: in, is the permanent magnet pole arc coefficient, α is the motor fundamental wave toothing torque period, α=360÷N; N is the number of motor fundamental wave toothing torque periods, N=LCM(Z, 8), LCM means taking the least common multiple, Z is the number of the plurality of tooth slots 201; θ0 is the central angle corresponding to each permanent magnet when all the permanent magnets are equally spaced, that is, The center angle corresponding to the first permanent magnet 101 of the motor rotor 1 in the four-pole synchronous motor is different from the center angle corresponding to the second permanent magnet 103, which can effectively reduce the cogging torque of the four-pole synchronous motor, and the structure is simple. Further, the number of tooth slots 201 of the motor stator 2 is different, the center angle values ​​corresponding to the first permanent magnet 101 of the motor rotor 1 are different, and the center angle corresponding to the second permanent magnet 103 is also different. The center angle corresponding to the first permanent magnet 101 and the center angle corresponding to the second permanent magnet 103 determined according to the number of tooth slots 201 of the motor stator 2 can further reduce the cogging torque of the four-pole motor with Z tooth slots 201, avoid motor speed fluctuations, vibrations and noise caused by large cogging torque, and the structure is simple, reducing the difficulty of processing.

[0037] Furthermore, the N poles and S poles of the adjacent permanent magnets are arranged at different poles. The N poles and S poles of the adjacent permanent magnets in the four-pole synchronous motor are arranged at different poles to form a predetermined magnetic field and magnetic flux lines.

[0038] Furthermore, adjacent permanent magnets are provided with gaps or separated by barrier blocks. If two adjacent permanent magnets are in direct contact, the two magnetic poles formed by the two permanent magnets are transformed into one magnetic pole, and thus the expected magnetic field cannot be formed.

[0039] Furthermore, the first permanent magnet 101 and the second permanent magnet 103 are both arc-shaped magnetic steel sheets. Usually, the iron core of the motor rotor 1 is cylindrical. The first permanent magnet 101 and the second permanent magnet 103 are both arc-shaped permanent magnet sheets, which are easier to fit the rotor core. Further, the motor rotor 1 is a surface-mounted rotor, and the second permanent magnet 103 and the seven first permanent magnets 101 are pasted and arranged on the outer circumferential surface of the motor rotor 1. The structure is simple and easy to fix, and compared with motors with stator skew slots and rotor skew poles or segmented staggered rotor poles, the processing difficulty is reduced.

[0040] There are many choices for matching the pole slots or tooth slots 201 of a four-pole synchronous motor, including four-pole 9-slots, four-pole 12-slots, four-pole 15-slots, four-pole 18-slots, four-pole 24-slots, four-pole 36-slots and other pole slot combinations. The following takes a four-pole 12-slot motor 201 as an example to explain the distribution of permanent magnets and the central angles corresponding to the permanent magnets: In a four-pole synchronous motor with 12 tooth slots 201, Z=12, the motor's fundamental tooth slot torque cycle number N, N=LCM(Z, 8)=24; the motor's fundamental tooth slot torque cycle α, α=360÷N=360÷24=15; the average value of the central angles corresponding to the seven first permanent magnets 101 and the second permanent magnet 103 or the central angle corresponding to each permanent magnet when all permanent magnets of the motor rotor 1 are equally divided Among them, take the permanent magnet pole arc coefficient Then, the central angle of the first permanent magnet 101 is The central angle corresponding to the second permanent magnet 103

[0041] By performing finite element analysis on various four-pole synchronous motors, a motor in which all permanent magnets of a motor rotor 1 have equal central angles is shown in the cross-sectional schematic diagram of the motor rotor 1. Figure 1 As shown, each pole divides the permanent magnet 100 degrees. Polar arc coefficient =1, the waveform of the cogging torque is as follows: Figure 4 As shown, Figure 4 The horizontal axis is time; the vertical axis is the cogging torque, and the unit is the motor torque fluctuation. The fluctuation value of the cogging torque is 52mNM. The cogging torque waveform of the 12-slot four-pole synchronous motor in the embodiment of the present application is as follows: Figure 5 As shown in the figure, the fluctuation value of the machine torque is the cogging torque, which is 13.5 mNM. Figure 4 and Figure 5 In the cogging torque waveform diagram shown: the horizontal axis is time, the unit is ms; the vertical axis is cogging torque, the unit is mNM.

[0042] The results show that the cogging torque of the four-pole synchronous motor in the present application is significantly reduced compared to the motor with the permanent magnets arranged equally.

[0043] Correspondingly, the four-pole synchronous motor pole slots or tooth slots 201 are matched, and there are multiple pole slots matching such as four-pole 9 slots, four-pole 12 slots, four-pole 15 slots, four-pole 18 slots, four-pole 24 slots, four-pole 36 slots, etc. Among them, the synchronous motor with four-pole Z tooth slots 201 calculates and configures the angles of the center angles corresponding to the first permanent magnet 101 and the second permanent magnet 103 according to the conditions and formulas in the above technical solution, which are not listed one by one here, and can effectively reduce the tooth slot torque, avoid motor speed fluctuations, vibrations and noise caused by large tooth slot torque, and has a simple structure, reducing the difficulty of processing.

[0044] Another aspect of the present application provides a method for reducing the cogging torque of a four-pole synchronous motor, wherein the four-pole synchronous motor comprises a motor rotor and a motor stator, wherein eight permanent magnets constitute four poles of the motor rotor; the motor stator has a plurality of tooth slots; the steps of the method for reducing the cogging torque of the four-pole synchronous motor include: S1. According to the number Z of tooth slots 201 of the motor stator 2 of the four-pole synchronous motor, determine the fundamental wave cogging torque cycle number N of the motor, N=LCM(Z, 8); S2. According to the fundamental wave cogging torque cycle number N of the motor, determine the fundamental wave cogging torque cycle α of the motor, α=360÷N; S3. Calculate the central angle θ0 corresponding to each of the permanent magnets when the central angles corresponding to the eight permanent magnets are equally divided, in, is the permanent magnet pole arc coefficient, S4. Determine the central angle θ1 corresponding to the seven first permanent magnets 101 among the eight permanent magnets, satisfying the relationship: S5. Determine the central angle θ2 corresponding to a second permanent magnet 103 among the eight permanent magnets, satisfying the relationship: The method of the present application can be applied to the four-pole synchronous motor in the above-mentioned embodiment, and the eight permanent magnets of the four-pole synchronous motor are unequally divided, specifically including seven equally divided first permanent magnets 101 and one unequally divided second permanent magnet 103; according to the number of tooth slots 201 of the motor stator 2, the fundamental wave tooth slot torque period number N and the motor fundamental wave tooth slot torque period α are determined; then based on the center angle θ0 corresponding to each of the permanent magnets when the center angles corresponding to the eight permanent magnets are equally divided, the center angle θ1 corresponding to the seven first permanent magnets 101 and the center angle θ2 corresponding to the second permanent magnet 103 are determined. In the present application, the center angle corresponding to each of the eight permanent magnets of the motor rotor 1 is determined according to the number of tooth slots 201 of the motor stator 2, which can effectively reduce the tooth slot torque and avoid motor speed fluctuations, vibrations and noise caused by large tooth slot torque. The structure is simple and the processing difficulty is reduced.

[0045] Furthermore, the method further comprises: arranging the N poles and S poles of the adjacent permanent magnets in different polarity intervals. Furthermore, the N poles and S poles of the adjacent permanent magnets are arranged in different polarity intervals. The N poles and S poles of the adjacent permanent magnets in the four-pole synchronous motor are arranged in different polarity intervals to form a predetermined magnetic field and magnetic flux lines.

[0046] It should be understood that the above specific embodiments of the present application are only used to illustrate or explain the principles of the present application, and do not constitute a limitation to the present application. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present application should be included in the protection scope of the present application. In addition, the claims attached to the present application are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A four-pole synchronous motor, characterized in that: include: The motor stator is provided with a plurality of tooth slots; A motor rotor, wherein seven first permanent magnets and one second permanent magnet constitute four pairs of poles of the motor rotor; The central angle θ1 corresponding to the first permanent magnet satisfies the relationship: , the central angle θ2 corresponding to the second permanent magnet satisfies the relationship: ;in, is the permanent magnet pole arc coefficient, ∈(0, 1], α is the motor fundamental wave tooth slot torque period, α=360÷N; N is the number of motor fundamental wave tooth slot torque periods, N=LCM(Z, 8), Z is the number of the plurality of tooth slots; θ0 is the central angle corresponding to each permanent magnet when all the permanent magnets are equally spaced, that is, ; The N poles and S poles of the adjacent permanent magnets are arranged in opposite polarities and spaced apart from each other; Adjacent permanent magnets are provided with gaps or separated by blocking blocks.

2. The four-pole synchronous motor according to claim 1, characterized in that: The first permanent magnet and the second permanent magnet are both arc-shaped magnetic steel sheets.

3. The four-pole synchronous motor according to claim 2, characterized in that: The second permanent magnet and the seven first permanent magnets are bonded and arranged around the outer circumferential surface of the motor rotor.

4. The four-pole synchronous motor according to claim 1, characterized in that: The plurality of tooth slots is 12, and the permanent magnet pole arc coefficient Yes 1.

5. A method for reducing the cogging torque of a four-pole synchronous motor, applied to the four-pole synchronous motor according to any one of claims 1 to 4, characterized in that: The four-pole synchronous motor comprises a motor rotor and a motor stator, and eight permanent magnets constitute four pole pairs of the motor rotor; The motor stator has a plurality of tooth slots; The method for reducing the cogging torque of a four-pole synchronous motor comprises: S1. According to the number of tooth slots Z of the motor stator of the four-pole synchronous motor, determine the number of fundamental wave tooth slot torque cycles N of the motor, N = LCM (Z, 8); S2. According to the fundamental wave cogging torque cycle number N of the motor, determine the motor fundamental wave cogging torque cycle α, α = 360 ÷ N; S3. Calculate the center angle θ0 corresponding to each of the eight permanent magnets when the center angles of the eight permanent magnets are equally divided. ,in, is the permanent magnet pole arc coefficient, ∈(0, 1]; S4. Determine the central angle θ1 corresponding to the seven first permanent magnets among the eight permanent magnets, satisfying the relationship: ; S5. Determine the central angle θ2 corresponding to a second permanent magnet among the eight permanent magnets, satisfying the relationship: .

6. The method for reducing the cogging torque of a four-pole synchronous motor according to claim 5, characterized in that: The method further comprises: The N poles and S poles of the adjacent permanent magnets are arranged with different poles and intervals.

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