A low-vibration rotor modulation slot of a built-in integer-slot motor and a design method thereof

Abstract

The present invention discloses a low-vibration rotor modulation slot of a built-in integer slot motor and a design method thereof, determines the motor size parameters, performs electromagnetic modeling, simulates the air gap flux density waveform under the no-load operation condition of the motor, and solves the radial electromagnetic force; simulates the radial electromagnetic force distribution under the no-load operation condition of the motor, collects the radial electromagnetic force under the no-load operation condition; simulates the three-dimensional modal frequency of the motor, and calculates the modal frequencies of each order; based on the radial electromagnetic force and modal frequencies of each order under the no-load operation condition, simulates the vibration acceleration response of the motor under the no-load operation condition, and determines the radial electromagnetic force optimization target: constructs a tooth number order static modulation function, designs the rotor modulation slot, and when the waveforms of the actual static modulation function and the ideal static modulation function are infinitely close, the radial electromagnetic force is minimum. The method of the present invention is easy to process, has strong pertinence, and significantly improves the vibration effect of the motor.

Description

Technical Field

[0001] The invention belongs to the technical field of high-reliability and low-vibration permanent magnet motor manufacturing, and specifically relates to a low-vibration rotor modulation slot of a built-in integer slot motor and a design method thereof. Background Art

[0002] With the rapid development of China's new energy vehicle field, high-performance, high-reliability and high-speed built-in integer slot permanent magnet synchronous motors have received more and more attention, and a large number of studies have been carried out. High speed will inevitably bring about the problem of vibration of built-in integer slot permanent magnet motors. Excessive motor vibration will endanger the bearing life of the motor and damage the motor insulation, thereby causing irreversible losses. Therefore, it is of great significance to develop a built-in integer slot permanent magnet motor with low vibration performance. At present, the research on suppressing the vibration noise of built-in integer slot permanent magnet motors is mainly focused on suppressing 2-fold frequency vibration, but suppressing 2-fold frequency vibration will inevitably lead to a loss of torque density. In addition, the latest research shows that the radial force of the stator tooth order has the greatest impact on the vibration of the built-in integer slot permanent magnet motor, so it is urgent to carry out corresponding vibration reduction design research.

[0003] At present, the vibration reduction design methods for internal integral slot permanent magnet motors mainly include rotor segmented skew poles, permanent magnet shaping, rotor mixed poles, and stator auxiliary slot design, etc. However, these vibration reduction design methods have the disadvantages of difficult processing and insufficient efficacy. Summary of the invention

[0004] In view of the shortcomings in the prior art, the present invention provides a design method for low-vibration rotor modulation slots of a built-in integer slot motor. The method is easy to process and has strong pertinence. For integer slot permanent magnet motors, the effect of improving motor vibration is very significant. In addition, the structure also takes into account the improvement of motor torque density and the improvement of motor torque pulsation. While improving the operating reliability of the built-in integer slot permanent magnet motor, the operating stability of the built-in integer slot permanent magnet motor is further improved.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A design method for low-vibration rotor modulation slots of built-in integer slot motor:

[0007] Determine the size parameters of the built-in integer slot permanent magnet motor, perform electromagnetic modeling on the built-in integer slot permanent magnet motor, simulate the air gap flux density waveform under the no-load operation condition of the motor, and solve the radial electromagnetic force;

[0008] Simulate the radial electromagnetic force distribution of the motor under no-load operation, analyze the main radial electromagnetic force distribution characteristics under no-load operation, and collect the radial electromagnetic force under no-load operation;

[0009] Establish a three-dimensional model of the motor, simulate the three-dimensional modal frequency of the motor, and calculate the modal frequencies of each order;

[0010] The radial electromagnetic force and modal frequencies of each order under no-load operation are imported into the structural finite element software to simulate the vibration acceleration response of the motor under no-load operation, and determine the optimization target of the radial electromagnetic force: construct a static modulation function of the tooth number order, and design the rotor modulation slot. When the waveforms of the actual static modulation function and the ideal static modulation function are infinitely close, the radial electromagnetic force is minimized, and the optimal vibration acceleration performance of the motor under no-load operation is achieved.

[0011] According to a further technical solution, the built-in integer-slot permanent magnet motor is a 48-slot / 8-pole permanent magnet motor.

[0012] A further technical solution is that the main radial electromagnetic force distribution characteristics under no-load operating conditions are as follows: the radial electromagnetic force of the stator teeth number of the built-in integer-slot permanent magnet motor is a 48th-order 12-fold frequency radial electromagnetic force, which is composed of the fundamental magnetic flux density and the 44th-order 11-fold frequency permanent magnet magnetic flux density harmonics, the fundamental magnetic flux density and the 52nd-order 13-fold frequency permanent magnet magnetic flux density harmonics.

[0013] According to a further technical solution, the 48th order 12-fold frequency radial electromagnetic force comprises two components, and the synthetic phase distribution of the two components is:

[0014] ∠F (4,44) =∠B r_4 +∠B r_44 =0

[0015] ∠F (4,52) =∠B r_52 -∠B r_4 =π

[0016] Among them, ∠F (4,44) It represents the phase of the 48th order 12-fold frequency radial electromagnetic force composed of the fundamental magnetic flux density and the 44th harmonic magnetic flux density, ∠F (4,52) It represents the phase of the 48th order 12-fold frequency radial electromagnetic force composed of the fundamental magnetic flux density and the 52nd harmonic magnetic flux density, ∠B r_4 Indicates the phase of the slotless fundamental magnetic flux density, ∠B r_44 Indicates the 44th harmonic flux density phase, ∠B r_52 Indicates the 52nd harmonic flux density phase.

[0017] According to a further technical solution, the rotor modulation slots are evenly distributed on the outer surface of the rotor core.

[0018] According to a further technical solution, when the radial electromagnetic force is minimum, the number of the rotor modulation slots is 48.

[0019] According to a further technical solution, the rotor modulation groove has an opening angle of 150 degrees and a depth of 0.1 mm.

[0020] A further technical solution is that the harmonic modulation process generated by the static modulation function of the fundamental magnetic flux density and the rotor modulation slot is:

[0021]

[0022] Among them, B syn_vp Indicates the harmonic amplitude of the modulated flux density, B ini_vp Indicates the harmonic amplitude of the flux density before modulation, B ini_p (t0) represents the fundamental magnetic flux density amplitude before modulation at time t0, M r_(v-1)p (t0) represents the (v-1)pth harmonic of the stator modulation function at time t0, M r_(v+1)p (t0) represents the (v+1)pth harmonic of the stator modulation function at time t0.

[0023] A low-vibration rotor modulation slot of a built-in integer-slot motor, wherein the rotor modulation slots are evenly distributed on the outer surface of a rotor core.

[0024] In the above technical solution, when the radial electromagnetic force of the 48-slot / 8-pole permanent magnet motor is minimum under no-load operation condition, the number of rotor modulation slots is 48.

[0025] The beneficial effects of the present invention are:

[0026] (1) After the built-in integer-slot permanent magnet motor of the present invention adopts the rotor modulation slot rear slot design, the vibration of the motor under no-load operation condition is significantly suppressed, and the operation stability and reliability are significantly improved.

[0027] (2) The rotor modulation slot design method adopted by the present invention has a simple processing technology and high portability, breaks through the blindness of the original rotor auxiliary slot design, and has a strong vibration suppression directionality.

[0028] (3) The rotor modulation slots used in the present invention are relatively small in size, which can almost not lose the torque density of the motor, and even improve the torque performance of the motor, thereby achieving a high-quality vibration suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1( a ) is a schematic diagram of the structure of the low-vibration rotor modulation slot of the built-in integer slot motor according to the present invention;

[0030] FIG1( b ) is a three-dimensional structural diagram of a rotor with modulation slots according to the present invention;

[0031] Figure 2 A schematic diagram of a rotor static modulation process for a low-vibration rotor core according to the present invention;

[0032] Figure 3 A comparison diagram of the ideal and actual rotor static modulation function waveforms of the present invention;

[0033] Figure 4(a) is the no-load radial electromagnetic force spectrum diagram under the original rotor structure;

[0034] Figure 4(b) is a spectrum diagram of the no-load radial electromagnetic force under the low-vibration rotor modulation slot structure;

[0035] Figure 5 This is a comparison diagram of no-load vibration acceleration before and after the low-vibration rotor modulation slot of the present invention is used;

[0036] Figure 6 This is a comparison diagram of the no-load cogging torque waveform before and after the low-vibration rotor modulation slot of the present invention is used;

[0037] Figure 7 This is a flow chart of the design method of the low-vibration rotor modulation slot of the built-in integer slot motor according to the present invention;

[0038] In the figure, 1- rotor core, 2- magnetic steel air slot, 3- rotor magnetic steel, 4- rotor modulation slot. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In order to more simply and clearly illustrate the beneficial effects of the present invention, a specific integer slot permanent magnet synchronous motor is described in detail below.

[0040] like Figure 7 As shown, the design method of a low-vibration rotor modulation slot of a built-in integer slot motor of the present invention comprises the following specific steps:

[0041] Step (1), according to the operating power, operating conditions and application fields of the built-in integer slot motor, calculate and determine the size parameters of the motor, the size parameters include size, main structure, slot-pole combination and motor material, the size parameters specifically include the main size of the motor, rotor magnetic steel arrangement, winding form, number of stator slots, number of rotor poles, stator and rotor materials, permanent magnet materials, and armature winding materials;

[0042] In this embodiment, the main dimensions of the motor are: the stator outer diameter is 155mm, the stator inner diameter is 100mm, the rotor outer diameter is 98.7mm, and the rotor core inner diameter is 36mm; in this embodiment, the rotor magnetic steel adopts an embedded V-shaped structure; in this embodiment, the number of stator slots of the motor is 48 slots, and the number of rotor poles is 8 poles; in this embodiment, the winding winding method is a distributed single-layer integer slot span, and the winding span is 5; in this embodiment, the stator and rotor materials are B20AT1500, the permanent magnet material is N38SH, and the armature winding material is round copper wire.

[0043] Step (2), after determining the size parameters of the motor, electromagnetic modeling of the built-in integer slot permanent magnet motor is performed using ANSYS Electronics Desktop finite element simulation software, the electromagnetic performance of the motor under no-load operation conditions is simulated, and it is verified whether the electromagnetic performance under no-load operation conditions meets the design index requirements. In this embodiment, the electromagnetic performance of the motor includes the air gap flux density waveform.

[0044] From the air gap flux density waveform, the air gap flux density formula of the motor is obtained as follows:

[0045]

[0046] Among them, B pm and B arm They represent the no-load permanent magnet flux density and armature flux density respectively, B pm_vp and B arm_np They represent the slotless permanent magnet flux density and slotless armature flux density amplitude, M sk represents the air gap magnetic field modulation function, p represents the number of rotor pole pairs, v and n represent the harmonic order, θ represents the spatial angle, and f e represents the electrical frequency, t0 represents the initial time, Z represents the number of stator teeth of the motor, and k represents a positive integer.

[0047] According to the air gap flux density of the motor, the radial electromagnetic force is expressed as:

[0048]

[0049] Among them, F r represents the radial electromagnetic force, and μ0 represents the magnetic permeability of vacuum.

[0050] Step (3), simulating the radial electromagnetic force distribution under the no-load operating condition of the motor, analyzing the main radial electromagnetic force distribution characteristics under the no-load operating condition, and collecting radial electromagnetic force data under the no-load operating condition.

[0051] For the built-in integer slot permanent magnet motor, under no-load operation, the radial electromagnetic force harmonic amplitude of the stator teeth is large and contributes the most to the vibration. The radial electromagnetic force of the stator teeth is a 48th order 12-fold frequency radial electromagnetic force, which is mainly composed of the fundamental magnetic flux density and the 44th order 11-fold frequency permanent magnet magnetic flux density harmonic, the fundamental magnetic flux density and the 52nd order 13-fold frequency permanent magnet magnetic flux density harmonic. Among them, the composition of the main radial electromagnetic force is shown in Table 1.

[0052] Table 1 Main radial electromagnetic force composition

[0053]

[0054]

[0055] The air gap flux density waveform is subjected to Fourier decomposition. Further, the phase relationship between the fundamental flux density, the 44th-order 11-fold frequency permanent magnet flux density harmonic, and the 52nd-order 13-fold frequency permanent magnet flux density harmonic is analyzed, as shown in Table 2, so as to determine the phase relationship between different radial electromagnetic force components.

[0056] Table 2 Main radial electromagnetic force components, magnetic flux density amplitude and phase relationship

[0057]

[0058] It can be seen from Table 2 that the composition of the 48th order 12-fold frequency radial electromagnetic force mainly includes two components, and its synthetic phase distribution is shown in the following formula:

[0059] ∠F (4,44) =∠B r_4 +∠B r_44 =0(4)

[0060] ∠F (4,52) =∠B r_52 -∠B r_4 =π(5)

[0061] Among them, ∠F (4,44) It represents the phase of the 48th order 12-fold frequency radial electromagnetic force composed of the fundamental magnetic flux density and the 44th harmonic magnetic flux density, ∠F (4,52) It represents the phase of the 48th order 12-fold frequency radial electromagnetic force composed of the fundamental magnetic flux density and the 52nd harmonic magnetic flux density, ∠B r_4 Indicates the phase of the slotless fundamental magnetic flux density, ∠B r_44 Indicates the 44th harmonic flux density phase, ∠B r_52 Indicates the 52nd harmonic flux density phase.

[0062] The radial electromagnetic force data within the air gap circle at all times under no-load operation conditions within an electrical cycle is simulated to realize radial electromagnetic force data collection.

[0063] Step (4), based on the size parameters of the motor, establish a three-dimensional model of the motor in the structural finite element software ANSYS, clarify the material properties of each component of the motor (including the stator and rotor, end cover, casing, bolts, and insulating cover), the material properties of each component of the motor mainly include the Young's modulus, shear modulus, material density, and material Poisson's ratio of the material; clarify the matching relationship between the components and the contact surface setting. In the embodiment, an interference fit is adopted between the casing and the stator core, a clearance fit is adopted between the end cover and the casing, and an adhesive fit is adopted between the insulating cover and the stator; simulate the three-dimensional modal frequency of the motor, and calculate the specific frequency of each order mode.

[0064] Step (5) imports the radial electromagnetic force data and each order modal frequency data under no-load operation into the structural finite element software ANSYS to simulate the vibration response of the motor under no-load operation. In this embodiment, the motor vibration response is the vibration acceleration response. Observe the distribution of the vibration acceleration response, as shown in the attached figure. Figure 5 As shown, the vibration acceleration before optimization is the largest at the 12th frequency. According to step (3), the vibration acceleration at the 12th frequency is excited by the radial electromagnetic force of the stator teeth (48th order 12th frequency radial electromagnetic force); therefore, the 48th order 12th frequency radial electromagnetic force component that has the main influence on the vibration is set as the optimization target.

[0065] According to Table 2, in order to achieve the suppression of the 48th order 12th frequency radial electromagnetic force, it is necessary to comprehensively suppress the 44th order 11th frequency permanent magnet flux density harmonics and the 52nd order 13th frequency permanent magnet flux density harmonics, which is achieved by adding the low-vibration rotor modulation slot structure described in the present invention.

[0066] Since the fundamental permanent magnet flux density harmonic will produce a modulation effect with the low-vibration rotor modulation slot structure, new 44th-order 11-fold frequency permanent magnet flux density harmonics and 52nd-order 13-fold frequency permanent magnet flux density harmonics are generated. The new 44th-order 11-fold frequency permanent magnet flux density harmonics and 52nd-order 13-fold frequency permanent magnet flux density harmonics are vector-superimposed with the 44th-order 11-fold frequency permanent magnet flux density harmonics and 52nd-order 13-fold frequency permanent magnet flux density harmonics when the modulation slot is not added, and finally the two permanent magnet flux density harmonics are offset.

[0067] Among them, the expression of the static modulation function of the rotor modulation slot is as follows:

[0068]

[0069] Among them, M r represents the static modulation function of the rotor modulation slot, M r0 represents the DC component of the rotor modulation slot static modulation function, M rjrepresents the jth harmonic component of the static modulation function of the rotor modulation slot, where j represents a positive integer. represents the phase angle at the initial moment.

[0070] The harmonic modulation process generated by the static modulation function of the fundamental magnetic flux density and the rotor modulation slot is as follows:

[0071]

[0072] Among them, B syn_vp Indicates the harmonic amplitude of the modulated flux density, B ini_vp Indicates the harmonic amplitude of the flux density before modulation, B ini_p (t0) represents the fundamental magnetic flux density amplitude before modulation at time t0, M r_(v-1)p (t0) represents the (v-1)pth harmonic of the stator modulation function at time t0, M r_(v+1)p (t0) represents the (v+1)pth harmonic of the stator modulation function at time t0.

[0073] According to formula (7), in order to generate new 44th-order 11-fold frequency permanent magnet flux density harmonics and 52nd-order 13-fold frequency permanent magnet flux density harmonics by static modulation, v must be equal to 12 at this time, that is, it is necessary to construct a 12p(48)-order rotor static modulation function within the motor air gap circle.

[0074] Therefore, as long as the 48th harmonic component of the rotor static modulation function is designed in a targeted manner, the radial electromagnetic force can be minimized; in order to obtain a purer 48th harmonic component, the rotor modulation slots need to be evenly distributed on the outer surface of the rotor core.

[0075] Figure 1(a) is a schematic diagram of the low-vibration rotor modulation slot structure of the built-in integer-slot motor described in the present invention. In order to ensure the optimal design of the radial electromagnetic force suppression effect, the rotor modulation slots are evenly distributed on the outer surface of the rotor core; Figure 1(b) is a three-dimensional structural diagram of the complete rotor with modulation slots.

[0076] Step (6), optimize the design of the rotor modulation slot, optimize the position, slot angle and slot depth of the modulation slot, obtain the optimal modulation slot parameters, optimize the amplitude and phase of the static modulation function harmonics, minimize the 48th order 12-fold frequency radial electromagnetic force, and thus achieve the optimal vibration acceleration performance under the no-load operating condition of the motor.

[0077] Figure 2Schematic diagram of the rotor static modulation process for the low-vibration rotor core of the present invention. Among them, after the initial fundamental slotless permanent magnet flux density waveform is modulated by the rotor modulation slot, a new 44th order 11-fold frequency permanent magnet flux density harmonic and 52nd order 13-fold frequency slotless permanent magnet flux density harmonic are generated, and then superimposed with the 44th and 52nd order slotless permanent magnet flux density when the modulation slot is not added, so that the phase and amplitude of the synthesized 44th order 11-fold frequency permanent magnet flux density harmonic and 52nd order 13-fold frequency permanent magnet flux density harmonic are optimal, and the minimization design of the 48th order 12-fold frequency radial electromagnetic force is achieved, that is, within a motor air gap circumference, the rotor modulation slot static modulation function needs to fluctuate 48 times, and the fluctuation period is evenly distributed. Therefore, the final number of rotor modulation slots is 48, evenly arranged on the rotor core. By scanning parameters to optimize the slot opening angle and depth of the modulation slot, the actual rotor static modulation function waveform is infinitely close to the ideal rotor modulation slot static modulation function. The final rotor modulation slot opening angle is 150 degrees and the modulation slot depth is 0.1 mm.

[0078] Figure 3 This is a comparison diagram of the ideal and actual rotor modulation slot static modulation function waveforms of the present invention. It can be seen from the figure that the ideal rotor modulation slot static modulation function waveform is different from the actual rotor modulation slot static modulation function waveform. This is because the actual rotor modulation slot static modulation function waveform contains harmonics of other components. However, the remaining harmonics do not react with the initial fundamental slotless permanent magnet flux density to produce a 48th order 12-fold frequency radial electromagnetic force, and therefore do not affect the actual optimization effect. As long as the 48th harmonic phase and harmonic amplitude of the ideal and actual rotor modulation slot static modulation functions are the same, the preset goal of minimizing the 48th order 12-fold frequency radial electromagnetic force can be achieved.

[0079] Figure 4(a) shows the no-load radial electromagnetic force spectrum under the original rotor structure, and Figure 4(b) shows the no-load radial force spectrum under the low-vibration rotor modulation slot structure. It can be seen that when the low-vibration rotor modulation slot design is adopted, the no-load 48th order 12-fold frequency radial electromagnetic force increases from 10468N / cm 2 Down to 3125N / cm 2 Therefore, it can be judged that after adopting the low-vibration rotor modulation slot of the present invention, the main radial electromagnetic force weakening effect of the 48-slot 8-pole internal integer slot permanent magnet motor in this embodiment under no-load operation condition is significant.

[0080] Figure 5 This is a comparison of the no-load vibration acceleration before and after the low-vibration rotor modulation slot of the present invention is used. It can be seen from the figure that after the low-vibration rotor modulation slot of the present invention is used, the vibration acceleration at the 12th frequency is increased from the original 4.8m / s 2 Down to 1.0m / s 2 , the vibration suppression effect is significant.

[0081] Figure 6 This is a comparison diagram of the no-load cogging torque waveform before and after the low-vibration rotor modulation slot of the present invention is used. It can be seen that after the low-vibration rotor modulation slot of the present invention is used, the cogging torque peak value is reduced from 12Nm to 5.4Nm.

[0082] In summary, the design method of the low-vibration rotor modulation slot of the built-in integer-slot motor of the present invention can provide a reference for suppressing electromagnetic vibration of the built-in integer-slot permanent magnet motor and improving the operating reliability of the motor.

[0083] Although the present invention has been disclosed as above with preferred embodiments, the embodiments are not intended to limit the present invention. Any equivalent changes or modifications made without departing from the spirit and scope of the present invention shall fall within the scope of protection defined by the appended claims of this application.

Claims

1. A design method for low-vibration rotor modulation slots of a built-in integer slot motor, characterized in that: Determine the size parameters of the built-in integer slot permanent magnet motor, perform electromagnetic modeling on the built-in integer slot permanent magnet motor, simulate the air gap flux density waveform under the no-load operation condition of the motor, and solve the radial electromagnetic force; Simulate the radial electromagnetic force distribution of the motor under no-load operation, analyze the main radial electromagnetic force distribution characteristics under no-load operation, and collect the radial electromagnetic force under no-load operation; Establish a three-dimensional model of the motor, simulate the three-dimensional modal frequency of the motor, and calculate the modal frequencies of each order; The radial electromagnetic force and modal frequencies of each order under no-load operation are imported into the structural finite element software to simulate the vibration acceleration response of the motor under no-load operation and determine the optimization target of the radial electromagnetic force: construct a static modulation function of the tooth number order and design the rotor modulation slot. When the waveforms of the actual static modulation function and the ideal static modulation function are infinitely close, the radial electromagnetic force is minimized, and the optimal vibration acceleration performance of the motor under no-load operation is achieved. The tooth number order static modulation function is: Among them, M r represents the static modulation function of the rotor modulation slot, M r0 represents the DC component of the rotor modulation slot static modulation function, M rj represents the jth harmonic component of the static modulation function of the rotor modulation slot, where j represents a positive integer. represents the phase angle at the initial moment, p represents the number of rotor pole pairs, and θ represents the spatial angle.

2. The design method of low-vibration rotor modulation slot of built-in integer slot motor according to claim 1 is characterized in that: The built-in integer-slot permanent magnet motor is a 48-slot / 8-pole permanent magnet motor.

3. The design method of low-vibration rotor modulation slot of built-in integer slot motor according to claim 2 is characterized in that: The main radial electromagnetic force distribution characteristics under no-load operating conditions are as follows: the radial electromagnetic force of the stator teeth number of the built-in integer-slot permanent magnet motor is a 48th-order 12-fold frequency radial electromagnetic force, which is composed of the fundamental magnetic flux density and the 44th-order 11-fold frequency permanent magnet magnetic flux density harmonics, the fundamental magnetic flux density and the 52nd-order 13-fold frequency permanent magnet magnetic flux density harmonics.

4. The design method of low-vibration rotor modulation slot of built-in integer slot motor according to claim 3 is characterized in that: The 48th order 12-fold frequency radial electromagnetic force includes two components, and the synthetic phase distribution of the two components is: ∠F (4,44) =∠B r_4 +∠B r_44 =0 ∠F (4,52) =∠B r_52 -∠B r_4 =π Among them, ∠F (4,44) It represents the phase of the 48th order 12-fold frequency radial electromagnetic force composed of the fundamental magnetic flux density and the 44th harmonic magnetic flux density, ∠F (4,52) It represents the phase of the 48th order 12-fold frequency radial electromagnetic force composed of the fundamental magnetic flux density and the 52nd harmonic magnetic flux density, ∠B r_4 Indicates the phase of the slotless fundamental magnetic flux density, ∠B r_44 Indicates the 44th harmonic flux density phase, ∠B r_52 Indicates the 52nd harmonic flux density phase.

5. The design method of low-vibration rotor modulation slots of a built-in integer slot motor according to claim 2, characterized in that: The rotor modulation grooves are evenly distributed on the outer surface of the rotor core.

6. The design method of low-vibration rotor modulation slots of a built-in integral slot motor according to claim 5, characterized in that: When the radial electromagnetic force is minimum, the number of rotor modulation slots is 48.

7. The design method of low-vibration rotor modulation slots of a built-in integral slot motor according to claim 6, characterized in that: The rotor modulation groove has an opening angle of 150 degrees and a depth of 0.1 mm.

8. The design method of low-vibration rotor modulation slots of a built-in integral slot motor according to claim 3, characterized in that: The harmonic modulation process generated by the static modulation function of the fundamental magnetic flux density and the rotor modulation slot is: Among them, B syn_vp Indicates the harmonic amplitude of the modulated flux density, B ini_vp Indicates the harmonic amplitude of the flux density before modulation, B ini_p (t0) represents the fundamental magnetic flux density amplitude before modulation at time t0, M r_(v-1)p (t0) represents the (v-1)pth harmonic of the stator modulation function at time t0, M r_(v+1)p (t0) represents the (v+1)pth harmonic of the stator modulation function at time t0.

9. A low-vibration rotor modulation slot of a built-in integer slot motor designed based on the design method according to any one of claims 1 to 8, characterized in that: The rotor modulation grooves are evenly distributed on the outer surface of the rotor core.

10. The low-vibration rotor modulation slot of the built-in integral slot motor according to claim 9, characterized in that: When the radial electromagnetic force of the 48-slot / 8-pole permanent magnet motor is minimum under no-load operation, the number of rotor modulation slots is 48.

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