Design method of asymmetrical rotor structure of permanent magnet motor and permanent magnet synchronous motor

Abstract

The embodiment of the application provides a design method of an asymmetric permanent magnet motor rotor structure and a permanent magnet synchronous motor. The method comprises the following steps: determining the relationship between the number of stator slots and the number of virtual rotor slots, so that the spatial order of electromagnetic force is greater than 4; designing a symmetric permanent magnet motor rotor structure based on the relationship between the number of stator slots and the number of virtual rotor slots; generating a magnetic pole offset angle according to the obtained highest torque harmonic order and the number of pole pairs; adjusting the pole pitch of adjacent magnetic poles in the symmetric permanent magnet motor rotor structure according to the magnetic pole offset angle, so that the offset angle of one magnetic pole is reduced and the offset angle of another magnetic pole is correspondingly increased, to obtain an asymmetric permanent magnet motor rotor structure. The asymmetric permanent magnet motor rotor structure can reduce the vibration noise of a vehicle motor, and improve the noise, vibration and harshness (Noise, Vibration, Harshness, referred to as NVH) performance and ride comfort of an automobile.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a design method for an asymmetric permanent magnet motor rotor structure and a permanent magnet synchronous motor. Background Technology

[0002] With the increasing severity of energy shortages and the deepening implementation of the "dual-carbon" strategy, permanent magnet motors, with their significant advantages such as high efficiency, high power density, and low loss, have become the core power unit for new energy vehicles. Mainstream automotive permanent magnet synchronous motors typically adopt a straight-line, V-type, or double-V-type structure. However, conventional built-in structures face the problem of complex electromagnetic harmonics leading to severe motor vibration and noise, seriously affecting vehicle ride comfort.

[0003] In related technologies, taking the V-shaped permanent magnet layout as an example, although the vibration and noise of the motor can be optimized by optimizing the angle of the V-shaped magnetic poles, the effect is often not ideal due to limitations such as efficiency and power density, resulting in relatively large vibration and noise in automotive motors. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a design method for an asymmetric permanent magnet motor rotor structure and a permanent magnet synchronous motor, in order to reduce the vibration and noise of automotive motors and improve the NVH performance and ride comfort of automobiles.

[0005] On one hand, embodiments of the present invention provide a design method for an asymmetric permanent magnet motor rotor structure, including: Determine the relationship between the number of stator slots and the number of rotor virtual slots so that the spatial order of electromagnetic force is greater than 4; A symmetrical permanent magnet motor rotor structure is designed based on the relationship between the number of stator slots and the number of rotor virtual slots. The magnetic pole offset angle is generated based on the highest torque harmonic order and the number of pole pairs obtained. The pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure is adjusted according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, thus obtaining the asymmetrical permanent magnet motor rotor structure.

[0006] Optionally, determining the relationship between the number of stator slots and the number of dummy rotor slots includes: The radial and tangential air gap magnetic flux densities were obtained through electromagnetic field analysis. The radial force density is determined based on the Maxwell stress tensor method according to the radial air gap magnetic flux density, the tangential air gap magnetic flux density and the vacuum permeability. The expression for the radial force density is also obtained based on the defined number of stator slots and rotor virtual slots and multiple sets of different harmonics, spatial position and time parameters. An expression for stator deformation is generated based on the radial force density and the obtained stator geometric parameters and distribution; The relationship between the number of stator slots and the number of rotor virtual slots is determined based on the expression for the radial force density and the expression for the stator deformation.

[0007] Optionally, the relationship between the number of stator slots and the number of dummy rotor slots includes: n s +4<n r <2n s -4, where n s n is the number of stator slots under a pair of poles. r The number of virtual slots of the rotor under a pair of poles.

[0008] Optionally, generating the magnetic pole offset angle based on the obtained highest torque harmonic order and number of pole pairs includes: Through formula The magnetic pole offset angle is generated by calculating the highest torque harmonic order and the number of pole pairs, wherein, denoted as the magnetic pole offset angle, p as the number of pole pairs, and h as the highest torque harmonic order.

[0009] Optionally, in the symmetrical permanent magnet motor rotor structure, the included angle between adjacent virtual slot points is determined according to the number of virtual slots in the rotor.

[0010] Optionally, in the symmetrical permanent magnet motor rotor structure, the virtual slots on both sides of the d-axis are combined in pairs in sequence to determine the spatial positions of the two ends of a magnetic barrier on the symmetrical permanent magnet motor rotor structure, and the magnetic barrier angle corresponds to the included angle between the two virtual slots.

[0011] Optionally, adjusting the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure according to the magnetic pole offset angle includes: The magnetic pole offset is achieved by moving the d-axis position in the symmetrical permanent magnet motor rotor structure, with the d-axis of one magnetic pole remaining fixed and the d-axis of the other magnetic pole moving by the magnetic pole offset angle.

[0012] On the other hand, embodiments of the present invention provide a permanent magnet synchronous motor, which is obtained according to the above-mentioned design method of the asymmetric permanent magnet motor rotor structure.

[0013] On the other hand, embodiments of the present invention provide a storage medium including a stored program, wherein the program controls the device where the storage medium is located to execute the above-described design method for an asymmetric permanent magnet motor rotor structure during runtime.

[0014] On the other hand, embodiments of the present invention provide a computer device including a memory and a processor. The memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions. When the program instructions are loaded and executed by the processor, the steps of the above-described design method for an asymmetric permanent magnet motor rotor structure are implemented.

[0015] In the technical solution provided by this invention, the relationship between the number of stator slots and the number of rotor virtual slots is determined to make the electromagnetic force spatial order greater than 4; a symmetrical permanent magnet motor rotor structure is designed based on the relationship between the number of stator slots and the number of rotor virtual slots; a magnetic pole offset angle is generated according to the obtained highest torque harmonic order and number of pole pairs; the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure is adjusted according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, resulting in an asymmetrical permanent magnet motor rotor structure. This asymmetrical permanent magnet motor rotor structure can reduce the vibration noise of automotive motors and improve the NVH performance and ride comfort of automobiles. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the 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.

[0017] Figure 1 A flowchart illustrating a design method for an asymmetric permanent magnet motor rotor structure according to an embodiment of the present invention; Figure 2 A flowchart illustrating a design method for another asymmetric permanent magnet motor rotor structure according to an embodiment of the present invention; Figure 3A This is a schematic diagram of a 36-slot, 4-pole, multi-layer built-in permanent magnet motor rotor structure provided in an embodiment of the present invention; Figure 3B This is a schematic diagram of a 36-slot, 6-pole multilayer built-in permanent magnet motor rotor structure according to an embodiment of the present invention. Figure 3C This is a schematic diagram of a 36-slot, 8-pole, multi-layer built-in permanent magnet motor rotor structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the rotor structure of a permanent magnet motor with different numbers of rotor slots according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the radial force of a permanent magnet assisted synchronous reluctance motor under different rotor slot numbers according to an embodiment of the present invention; Figure 6A schematic diagram of the main radial force harmonics under different rotor slot numbers provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of vibration acceleration under different rotor slot numbers according to an embodiment of the present invention; Figure 8 A schematic diagram of a symmetrical permanent magnet motor rotor structure provided in an embodiment of the present invention; Figure 9 A schematic diagram of an asymmetric permanent magnet motor rotor structure provided in an embodiment of the present invention; Figure 10A A comparison diagram of torque waveforms before and after magnetic pole offset provided in an embodiment of the present invention; Figure 10B This is a comparison diagram of torque harmonics before and after magnetic pole offset provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0018] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0021] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0022] One embodiment of the present invention provides a design method for an asymmetric permanent magnet motor rotor structure. By designing the pole arc angles of different magnetic poles, electromagnetic force harmonics are canceled, thereby achieving the purpose of suppressing motor vibration noise. Figure 1 A flowchart illustrating a design method for an asymmetric permanent magnet motor rotor structure according to an embodiment of the present invention is shown below. Figure 1 As shown, the method includes: Step 102: Determine the relationship between the number of stator slots and the number of rotor virtual slots, so that the spatial order of electromagnetic force is greater than 4.

[0023] In this embodiment of the invention, each step is performed by a computer device. For example, the computer device includes a computer, tablet computer, server, or simulation device.

[0024] In this embodiment of the invention, the relationship between the number of stator slots and the number of dummy rotor slots includes: n s +4<n r <2n s -4, where n s n is the number of stator slots under a pair of poles. r The number of virtual slots of the rotor under a pair of poles.

[0025] Step 104: Design a symmetrical permanent magnet motor rotor structure based on the relationship between the number of stator slots and the number of rotor virtual slots.

[0026] In this embodiment of the invention, the location of the rotor dummy slot is represented by the position of the end of the rotor magnetic barrier on the outer edge of the rotor. Generally, the rotor magnetic barriers under a pair of poles are symmetrically distributed, therefore the rotor dummy slots should also be evenly distributed on the outer circumference of the rotor, with the included angle between two adjacent dummy slots... (Mechanical angle) can be expressed as: , where n r Let be the number of virtual slots of the rotor under a pair of poles, and p be the number of pole pairs.

[0027] In this embodiment of the invention, in the symmetrical permanent magnet motor rotor structure, based on the structural symmetry, the virtual slot points on both sides of the d-axis are combined in pairs in sequence to determine the spatial positions of the two ends of a magnetic barrier on the rotor, and the magnetic barrier angle corresponds to the included angle between the two virtual slot points.

[0028] Step 106: Generate the magnetic pole offset angle based on the obtained highest torque harmonic order and number of pole pairs.

[0029] Specifically, through the formula The magnetic pole offset angle is generated by calculating the highest torque harmonic order and the number of pole pairs. denoted as the magnetic pole offset angle, p as the number of pole pairs, and h as the highest torque harmonic order.

[0030] Step 108: Adjust the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, to obtain an asymmetrical permanent magnet motor rotor structure.

[0031] In this embodiment of the invention, the magnetic pole offset is achieved by moving the d-axis position in the symmetrical permanent magnet motor rotor structure. The d-axis of one magnetic pole remains fixed, while the d-axis of the other magnetic pole moves by a magnetic pole offset angle, so that the offset angle of one magnetic pole decreases and the offset angle of the other magnetic pole increases accordingly, thus obtaining an asymmetrical permanent magnet motor rotor structure.

[0032] In the technical solution provided by this invention, the relationship between the number of stator slots and the number of rotor virtual slots is determined to make the electromagnetic force spatial order greater than 4; a symmetrical permanent magnet motor rotor structure is designed based on the relationship between the number of stator slots and the number of rotor virtual slots; a magnetic pole offset angle is generated according to the obtained highest torque harmonic order and number of pole pairs; the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure is adjusted according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, resulting in an asymmetrical permanent magnet motor rotor structure. This asymmetrical permanent magnet motor rotor structure can reduce the vibration noise of automotive motors and improve the NVH performance and ride comfort of automobiles.

[0033] One embodiment of the present invention provides a design method for another asymmetric permanent magnet motor rotor structure. Figure 2 A flowchart illustrating a design method for another asymmetric permanent magnet motor rotor structure according to an embodiment of the present invention. Figure 2 As shown, the method includes: For multi-layer magnet built-in permanent magnet motors, n is defined as follows: s n is the number of stator slots under a pair of poles. r The number of virtual slots on a pair of poles is denoted by the position of the rotor magnetic barrier end on the outer edge of the rotor. Generally, the rotor magnetic barriers on a pair of poles are symmetrically distributed, therefore the virtual slots should also be evenly distributed on the outer circumference of the rotor. The included angle between two adjacent virtual slots is... (Mechanical angle) can be expressed as: , where n r Let be the number of virtual slots of the rotor under a pair of poles, and p be the number of pole pairs.

[0034] In this embodiment of the invention, the included angle between adjacent virtual slots in the symmetrical permanent magnet motor rotor structure can be determined based on the number of virtual slots in the rotor.

[0035] In this embodiment of the invention, the included angle between adjacent virtual slot points is used as the core geometric parameter of the rotor virtual slot structure, and its value is determined by the number of rotor virtual slots n. r This angle directly determines not only the uniform distribution density of the rotor's virtual slots on the circumference, but also the periodic characteristics of the rotor's magnetic circuit. During motor operation, the rotor's virtual slots alter the air gap magnetic permeability distribution, and the angle between adjacent virtual slot points directly affects the frequency characteristics of this permeability change. Specifically, this angle is related to the number of stator slots, n. sThe spatial order of electromagnetic force harmonics is determined by these factors. When the spatial order is less than or equal to 4, the electromagnetic force will cause significant deformation of the stator, leading to noticeable vibration and noise. However, by precisely adjusting the angle between adjacent virtual slots, the spatial order can be made greater than 4, guiding the electromagnetic force harmonics to the high-frequency region, thereby significantly reducing their impact on vibration. Therefore, this angle is a crucial bridge connecting the electromagnetic design of the motor and vibration suppression, and its optimal selection is an important technical step in achieving low-vibration motor design.

[0036] In this embodiment of the invention, in the symmetrical permanent magnet motor rotor structure, based on the structural symmetry, the virtual slot points on both sides of the d-axis are combined in pairs in sequence to determine the spatial positions of the two ends of a magnetic barrier on the symmetrical permanent magnet motor rotor structure, and the magnetic barrier angle corresponds to the included angle between the two virtual slot points.

[0037] In this embodiment of the invention, the core purpose of determining the position and angle of the magnetic barrier is to optimize the harmonic characteristics of the electromagnetic force by precisely controlling the rotor reluctance distribution. Based on the symmetrical structure of the rotor, the virtual slots on both sides of the d-axis are sequentially combined in pairs to form magnetic barriers of different levels. The angle of each magnetic barrier is the angle between the corresponding virtual slots. This magnetic barrier structure design directly affects the harmonic composition of the air gap magnetic flux density, thus determining the amplitude and order distribution of the electromagnetic force. For example, for a 36-slot 4-pole motor, when the number of virtual slots n... r When the value is 22, the five magnetic barriers formed by a specific combination (with opening angles of 16.36°, 32.73°, 49.09°, 65.45°, and 81.82°, respectively) significantly reduce the radial force harmonic amplitude compared to other combinations; while when the rotor virtual slot number n r When the magnetic barrier angle is 14, only three magnetic barriers can be formed, leading to an increase in the proportion of low-order force waves and a significant increase in vibration noise. A reasonable combination of magnetic barrier angles can reduce motor vibration acceleration by more than 40% while reducing torque pulsation. This design essentially eliminates the source of vibration noise at its source by "tuning electromagnetic force with reluctance," rather than relying on post-dampening treatment. This maintains the high power density advantage of the motor while significantly improving NVH performance.

[0038] Figure 3A This is a schematic diagram of a 36-slot, 4-pole, multi-layer built-in permanent magnet motor rotor structure according to an embodiment of the present invention, as shown below. Figure 3A As shown, for a 36-slot 4-pole motor, it is easy to obtain n s It is 18. When n r When the value is 22, there are 11 virtual slots under one pole, and the angle between adjacent virtual slots is... The angle is 8.18°, and the distribution of these virtual slots on the rotor circumference is as follows: Figure 3AAs shown. Virtual slot point 0 is located on the rotor's q-axis. By combining the virtual slot points on either side of it in pairs, five magnetic barriers (A, B, C, D, E) are obtained. The magnetic barrier angles corresponding to each layer are 16.36°, 32.73°, 49.09°, 65.45°, and 81.82°, respectively. It can be seen that the rotor magnetic barriers of a 36-slot 4-pole motor can be combined in various ways (such as A, AB, BCD, ACE, ABCD, ABCDE), and the maximum number of barrier layers is 5. When n r When the angle is 14, the included angle between adjacent virtual slot points The angle is 12.86°, there are 7 virtual slots under one pole, and the maximum number of magnetic barrier layers of the rotor is only 3.

[0039] Figure 3B This is a schematic diagram of a 36-slot, 6-pole, multi-layer built-in permanent magnet motor rotor structure according to an embodiment of the present invention, as shown below. Figure 3B As shown, for a 36-slot 6-pole motor, there are a maximum of 4 magnetic barriers (F, G, H, I) under one pole, and the magnetic barrier angles corresponding to each magnetic barrier are 7.5°, 22.5°, 37.5°, and 52.5°, respectively.

[0040] Figure 3C This is a schematic diagram of a 36-slot, 8-pole, multi-layer built-in permanent magnet motor rotor structure according to an embodiment of the present invention, as shown below. Figure 3C As shown, for a 36-slot 8-pole motor, there are a maximum of 3 magnetic barriers (J, K, L) under one pole, and the magnetic barrier angles corresponding to each magnetic barrier are 6.92°, 20.77°, and 34.62°, respectively.

[0041] Regarding the permanent magnet motor rotor structure with the above-mentioned structural form, this embodiment of the invention proposes a relationship between the number of stator slots and the number of rotor virtual slots from the perspective of motor electromagnetic force waves and vibration noise, that is, the selection range of the number of stator slots and the number of rotor virtual slots.

[0042] Step 202: Obtain the radial air gap magnetic flux density and the tangential air gap magnetic flux density through electromagnetic field analysis.

[0043] In this embodiment of the invention, each step is performed by a computer device. For example, the computer device includes a computer, tablet computer, server, or simulation device.

[0044] In this embodiment of the invention, the radial air gap magnetic flux density B can be obtained through electromagnetic field analysis using finite element software. r and tangential air gap magnetic flux density B t .

[0045] Step 204: Based on the Maxwell stress tensor method, the radial force density is determined according to the radial air gap magnetic flux density, the tangential air gap magnetic flux density and the vacuum permeability. The expression for the radial force density is also obtained based on the defined number of stator slots and rotor virtual slots and multiple sets of different harmonics, spatial position and time parameters.

[0046] In this embodiment of the invention, considering that the tangential force is much smaller than the radial force and that the harmonics are the same as the radial force, only the radial force is analyzed here. The radial force density can be calculated according to Maxwell's stress tensor method as follows: (1) Where, σ r For radial force density, B r B is the radial air gap magnetic flux density. t Let μ be the tangential air gap magnetic flux density, μ0 be the free permeability, and B be the free permeability. mμ1 B mμ2 Let μ1 and μ2 be the harmonic amplitudes of the permanent magnet's magnetic field, and k be the permeability parameters. r1 k r2 k s1 k s2 n is the spatial harmonic order parameter. r n is the number of virtual slots of the rotor under a pair of poles. s Let ω1 be the number of stator slots under a single pole, t be the angular frequency, t be the time, p be the number of pole pairs, and θ be the number of stator slots under a single pole pair. s This refers to the angular position.

[0047] In this embodiment of the invention, the radial force harmonics of the multi-layer built-in permanent magnet motor under no-load conditions are generated by the interaction between the rotor magnetomotive force and the stator slots. Considering that the rotor magnetomotive force harmonics are generated by magnetic barriers and magnetic bridges, i.e., rotor virtual slots, the radial force harmonics under no-load conditions are determined by the interaction between the stator slots and the rotor virtual slots.

[0048] For permanent magnet synchronous motors, the harmonic order of the permanent magnet magnetic field is odd. Therefore, μ 1± μ2 is an odd number and can be represented as 2c1, where c1 is an integer. k r1 k r2 and k s1 k s2 Since it is an integer, k r1± k r2 and k s1± k s2 These are also integers, and are represented by c2 and c3. Based on the above analysis, the radial force under no-load conditions can be simplified to the following expression for the radial force density: (2) Step 206: Generate an expression for stator deformation based on the radial force density and the obtained stator geometric parameters and distribution.

[0049] In this embodiment of the invention, considering that the amplitude of the rotor magnetomotive force harmonics is much smaller than the amplitude of the fundamental wave, only the fundamental wave of the rotor magnetomotive force is considered, and or The spatial order of the radial force under no-load conditions is or Stator deformation can be calculated using Jordan's formula: (3) (4) Among them, Y s m For stator deformation, m is the spatial harmonic order, and R is the stator deformation. is R is the stator inner diameter. yoke Where is the stator yoke radius, E is the elastic modulus, and h is the value of the stator yoke. yoke For the stator yoke thickness, σ r，0 The radial force density is of order 0, σ r，m It is the m-th order radial force density.

[0050] In this embodiment of the invention, the stator deformation is inversely proportional to the fourth power of the spatial order, which indicates that lower-order force waves have a greater impact on the stator deformation.

[0051] Step 208: Determine the relationship between the number of stator slots and the number of rotor virtual slots based on the expressions for radial force density and stator deformation, so that the spatial order of electromagnetic force is greater than 4.

[0052] In this embodiment of the invention, stator deformation is related to low-order force waves, which in turn are related to the interaction between stator slots and rotor dummy slots. The following formula (5) can be used to guide the selection of a suitable combination of stator slots and rotor dummy slots to achieve low vibration and noise. Therefore, calculating stator deformation can provide a basis for determining a suitable combination of stator slots and rotor dummy slots. Stator deformation affects the performance of the motor, such as the uniformity of the air gap, and thus affects the electromagnetic performance of the motor. Stator deformation will generate vibration and noise, and vibration and noise are important indicators for measuring the quality of the motor. By calculating stator deformation, the vibration and noise levels of the motor can be analyzed and controlled to meet the requirements of practical applications for low vibration and noise of the motor.

[0053] In this embodiment of the invention, the relationship between the number of stator slots and the number of dummy rotor slots includes: n s +4<n r <2n s -4, where n s n is the number of stator slots under a pair of poles. r The number of virtual slots of the rotor under a pair of poles.

[0054] Specifically, in motor vibration theory, to avoid low-order force waves generated by the direct interaction between stator slots and rotor virtual slots, n s and n r The difference between them can be as large as possible. Generally speaking, when the spatial order of the electromagnetic force is greater than 4, the influence of the electromagnetic force on the motor vibration is relatively small. Therefore, n s and n r The relationship between them should satisfy and Therefore, the relationship between the stator slots and the rotor virtual slots can be obtained as follows: (5) The relationship between the number of stator slots and the number of rotor dummy slots can be used to guide the selection of the optimal combination of stator slots and rotor dummy slots to achieve low vibration and noise in multi-layer embedded permanent magnet motors.

[0055] Specifically, according to formula (2), the spatial order of electromagnetic force is or When considering spatial electromagnetic forces with a spatial order greater than 4, n s and n r The relationship between them should satisfy and In a permanent magnet synchronous reluctance motor, n r >n s And n s and n r All are positive integers. For inequalities ,when When the above inequality is simplified to Thus, the left side of formula (5) can be obtained. .when When the above inequality is simplified to Thus, the right side of formula (5) can be obtained. Meanwhile, considering that the number of stator slots and the number of rotor virtual slots should be kept as close as possible in the design, the equality signs on both sides of the inequality are removed, resulting in formula (5).

[0056] This invention provides a general selection criterion, and the value is within a range. This means that for a given model of motor, when considering motor vibration and noise, there is more than one optimal combination of stator slot number and rotor dummy slot number. In fact, motor performance is not only affected by vibration and noise, but also by other indicators such as torque density, power factor, and efficiency. The combination of stator slot number and rotor dummy slot number also affects other performance indicators. Therefore, it is necessary to comprehensively consider other indicators. The value range of the relationship between stator slot number and rotor dummy slot number given in this invention is selected comprehensively in formula (5). Therefore, the value range of the relationship between stator slot number and rotor dummy slot number given in this invention is reasonable and has practical application value.

[0057] Step 210: Design a symmetrical permanent magnet motor rotor structure based on the relationship between the number of stator slots and the number of rotor virtual slots.

[0058] Figure 4 This is a schematic diagram of a permanent magnet motor rotor structure with different numbers of rotor slots according to an embodiment of the present invention, as shown below. Figure 4 As shown, according to formula (5), n r =16 is an ideal choice for the number of virtual slots of a rotor within its range. Conversely, n r =14 and n r =22 is outside the range of formula (5). It can be seen that the rotor virtual slot changes the air gap magnetic permeability of the rotor, and further affects the air gap magnetic flux density and electromagnetic force. Figure 4 The reason for the different numbers of permanent magnets is to ensure different n r The output torque of the lower motor is the same.

[0059] Figure 5 This is a schematic diagram of the radial force of a permanent magnet assisted synchronous reluctance motor under different rotor slot numbers according to an embodiment of the present invention, with different n values ​​under no-load conditions. r The radial force of the motor is as follows Figure 5 As shown in the figure. It can be seen that different n r The three motors have basically the same spatial order and frequency, but different amplitudes.

[0060] Figure 6 This is a schematic diagram of the main radial force harmonics under different rotor slot numbers according to an embodiment of the present invention, as shown below. Figure 6 As shown, Figure 6 The main radial force harmonics were compared, and it can be seen that n r The rotor radial force harmonic amplitude is largest when n = 22, while n r When the value is 16, the rotor radial force harmonics are minimized, resulting in minimal vibration.

[0061] Figure 7This is a schematic diagram of vibration acceleration under different rotor slot numbers according to an embodiment of the present invention, as shown below. Figure 7 As shown, Figure 7 Three different n are given r The vibration acceleration of the motor can be seen from n r The multi-layer built-in permanent magnet motor exhibits minimal vibration at n=16, consistent with previous radial force analysis results. Further research into the influence of rotor virtual slots further demonstrates this. s and n r It can meet the design criteria of formula (5), thereby realizing the low vibration design of multi-layer built-in permanent magnet motor.

[0062] Figure 8 A schematic diagram of a symmetrical permanent magnet motor rotor structure provided in an embodiment of the present invention is shown below. Figure 8 As shown, the rotor electrical cycle is 120 mechanical degrees, and the distance between the two magnetic pole q axes is 60 mechanical degrees.

[0063] Step 212: Generate the magnetic pole offset angle based on the obtained highest torque harmonic order and number of pole pairs.

[0064] Based on the above steps, a low-vibration design for a multi-layer built-in permanent magnet motor can be achieved. To further reduce vibration and noise, this embodiment of the invention further adopts an asymmetric rotor magnetic pole design, as shown in steps 212-214.

[0065] Specifically, through the formula The magnetic pole offset angle is generated by calculating the highest torque harmonic order and the number of pole pairs. denoted as the magnetic pole offset angle (which can be expressed in mechanical angles), p is the number of pole pairs, and h is the highest torque harmonic order.

[0066] Step 214: Adjust the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, to obtain an asymmetrical permanent magnet motor rotor structure.

[0067] In this embodiment of the invention, the magnetic pole offset is achieved by moving the d-axis position in the symmetrical permanent magnet motor rotor structure. The d-axis of one magnetic pole remains fixed, while the d-axis of the other magnetic pole moves by a magnetic pole offset angle, so that the offset angle of one magnetic pole decreases and the offset angle of the other magnetic pole increases accordingly, thus obtaining an asymmetrical permanent magnet motor rotor structure.

[0068] Figure 9 This is a schematic diagram of an asymmetric permanent magnet motor rotor structure provided in an embodiment of the present invention, as shown below. Figure 9 As shown, the magnetic barrier offset is adjusted by changing the pole spacing between adjacent magnetic poles, and the magnetic pole offset angle is defined as... The d-axis of the offset motor is indicated by blue and red. The blue d-axis remains fixed, in the same position as a conventional motor; while the red d-axis has moved. Angle. This movement causes deformation of the magnetic poles: the offset angle of one magnetic pole decreases, while the offset angle of the other magnetic pole increases accordingly. The rotor ribs move along their respective d-axis. Figure 9 This is highlighted using color contrast.

[0069] Figure 10A This is a comparison diagram of torque waveforms before and after magnetic pole offset provided in an embodiment of the present invention. Figure 10B This is a comparison diagram of torque harmonics before and after magnetic pole offset provided in an embodiment of the present invention, as shown below. Figure 10A and Figure 10B As shown, MotA represents a rotor structure with no magnetic pole offset, and MotA-FBS represents a rotor structure with magnetic pole offset. It can be seen that magnetic pole offset can significantly reduce torque pulsation in multi-layer built-in permanent magnet motors, thereby suppressing vibration and noise.

[0070] In the technical solution provided by this invention, the relationship between the number of stator slots and the number of rotor virtual slots is determined to make the electromagnetic force spatial order greater than 4; a symmetrical permanent magnet motor rotor structure is designed based on the relationship between the number of stator slots and the number of rotor virtual slots; a magnetic pole offset angle is generated according to the obtained highest torque harmonic order and number of pole pairs; the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure is adjusted according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, resulting in an asymmetrical permanent magnet motor rotor structure. This asymmetrical permanent magnet motor rotor structure can reduce the vibration noise of automotive motors and improve the NVH performance and ride comfort of automobiles.

[0071] The technical solution provided in this invention embodiment can significantly reduce torque pulsation, electromagnetic harmonics, and vibration noise of multi-layer built-in permanent magnet motors compared to traditional rotor structures, thereby improving the NVH performance and ride comfort of new energy vehicles.

[0072] This invention provides a permanent magnet synchronous motor, which can be obtained based on the design method of the asymmetric permanent magnet motor rotor structure described above.

[0073] This invention provides a storage medium that includes a stored program. When the program runs, it controls the device where the storage medium is located to execute the steps of the above-described design method for an asymmetric permanent magnet motor rotor structure. For a detailed description, please refer to the above-described design method for an asymmetric permanent magnet motor rotor structure.

[0074] This invention provides a computer device, including a memory and a processor. The memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions. When the program instructions are loaded and executed by the processor, they implement the steps of the above-described design method for an asymmetric permanent magnet motor rotor structure. For a detailed description, please refer to the above-described design method for an asymmetric permanent magnet motor rotor structure.

[0075] Figure 11 This is a schematic diagram of a computer device provided in an embodiment of the present invention. Figure 11 As shown, the computer device 20 of this embodiment includes a processor 21, a memory 22, and a computer program 23 stored in the memory 22 and executable on the processor 21. When the computer program 23 is executed by the processor 21, it implements the design method of the rotor structure of the asymmetric permanent magnet motor in the embodiment. To avoid repetition, it will not be described in detail here.

[0076] Computer device 20 includes, but is not limited to, processor 21 and memory 22. Those skilled in the art will understand that... Figure 11 This is merely an example of computer device 20 and does not constitute a limitation on computer device 20. It may include more or fewer components than shown, or combine certain components, or different components. For example, computer device may also include input / output devices, network access devices, buses, etc.

[0077] The processor 21 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0078] The memory 22 can be an internal storage unit of the computer device 20, such as a hard disk or RAM of the computer device 20. The memory 22 can also be an external storage device of the computer device 20, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the computer device 20. Furthermore, the memory 22 can include both internal and external storage units of the computer device 20. The memory 22 is used to store computer programs and other programs and data required by the computer device. The memory 22 can also be used to temporarily store data that has been output or will be output.

[0079] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0080] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0081] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0082] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0083] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0084] The above description is only a preferred 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 scope of protection of the present invention.

Claims

1. A design method for an asymmetric permanent magnet motor rotor structure, characterized in that, include: Determine the relationship between the number of stator slots and the number of rotor virtual slots so that the spatial order of electromagnetic force is greater than 4; A symmetrical permanent magnet motor rotor structure is designed based on the relationship between the number of stator slots and the number of rotor virtual slots. The magnetic pole offset angle is generated based on the highest torque harmonic order and the number of pole pairs obtained. The pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure is adjusted according to the magnetic pole offset angle, so that the offset angle of one magnetic pole decreases while the offset angle of the other magnetic pole increases accordingly, thus obtaining the asymmetrical permanent magnet motor rotor structure.

2. The method according to claim 1, characterized in that, Determining the relationship between the number of stator slots and the number of dummy rotor slots includes: The radial and tangential air gap magnetic flux densities were obtained through electromagnetic field analysis. The radial force density is determined based on the Maxwell stress tensor method according to the radial air gap magnetic flux density, the tangential air gap magnetic flux density and the vacuum permeability. The expression for the radial force density is also obtained based on the defined number of stator slots and rotor virtual slots and multiple sets of different harmonics, spatial position and time parameters. An expression for stator deformation is generated based on the radial force density and the obtained stator geometric parameters and distribution; The relationship between the number of stator slots and the number of rotor virtual slots is determined based on the expression for the radial force density and the expression for the stator deformation.

3. The method according to claim 1, characterized in that, The relationship between the number of stator slots and the number of rotor virtual slots includes: n s +4<n r <2n s -4, where n s n is the number of stator slots under a pair of poles. r The number of virtual slots of the rotor under a pair of poles.

4. The method according to claim 1, characterized in that, The process of generating the magnetic pole offset angle based on the highest torque harmonic order and the number of pole pairs includes: Through formula The magnetic pole offset angle is generated by calculating the highest torque harmonic order and the number of pole pairs, wherein, denoted as the magnetic pole offset angle, p as the number of pole pairs, and h as the highest torque harmonic order.

5. The method according to claim 1, characterized in that, In the symmetrical permanent magnet motor rotor structure, the included angle between adjacent virtual slots is determined according to the number of virtual slots in the rotor.

6. The method according to claim 5, characterized in that, In a symmetrical permanent magnet motor rotor structure, the virtual slots on both sides of the d-axis are combined in pairs in sequence to determine the spatial positions of the two ends of a magnetic barrier on the symmetrical permanent magnet motor rotor structure. The magnetic barrier angle corresponds to the included angle between the two virtual slots.

7. The method according to claim 1, characterized in that, The step of adjusting the pole pitch of adjacent magnetic poles in the symmetrical permanent magnet motor rotor structure according to the magnetic pole offset angle includes: The magnetic pole offset is achieved by moving the d-axis position in the symmetrical permanent magnet motor rotor structure, with the d-axis of one magnetic pole remaining fixed and the d-axis of the other magnetic pole moving by the magnetic pole offset angle.

8. A permanent magnet synchronous motor, characterized in that, The design method of the asymmetric permanent magnet motor rotor structure according to any one of claims 1 to 7 is obtained.

9. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the design method of the asymmetric permanent magnet motor rotor structure according to any one of claims 1 to 7.

10. A computer device comprising a memory and a processor, the memory for storing information including program instructions, and the processor for controlling the execution of the program instructions, characterized in that, When the program instructions are loaded and executed by the processor, they implement the steps of the design method for the asymmetric permanent magnet motor rotor structure as described in any one of claims 1 to 7.

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